SYSTEMS AND METHODS FOR RETARDING THE SPEED OF A RAILCAR
A system for retarding a railcar. The system includes a brake and an actuator that moves the brake between a closed position in which the brake slows the railcar and an open position in which the brake does not slow the railcar. The system further includes a hydraulic circuit through which a hydraulic fluid flows between the actuator, a pump, and a reservoir. A variable speed motor drives the pump to supply the hydraulic fluid from the reservoir to the actuator. The variable speed motor is operable at a plurality of speeds between fully-on and fully-off states. A control system determines a speed setting within the plurality of speeds for operating the variable speed motor based on a pressure of the hydraulic fluid in the hydraulic circuit, the speed setting being determined such that the pressure is sufficient for operating the actuator.
Latest Precision Rail and Mfg., Inc. Patents:
This application claims the benefit of U.S. Provisional Patent Application No. 63/323,392, filed Mar. 24, 2022, which is incorporated herein by reference in its entirety.
FIELDThe present disclosure relates generally to systems and methods for controlling the movement of a railcar riding along a set of rails, including retarders suitable for reducing the speed of a railcar.
BACKGROUNDThe following are incorporated herein by reference in entirety.
U.S. Pat. No. 4,393,960, the disclosure of which is hereby incorporated herein by reference in entirety, discloses a brake shoe structure that includes a series of alternating long brake shoes and short brake shoes mountable on adjacent brake beams in a railroad car retarder. The length of the long brake shoe is such that the long brake shoe symmetrically straddles two adjacent brake beams. The length of the short brake shoe is such that the shoe occupies the spacing on the brake beams between two long brake shoes. The long brake shoes are affixable to each of the brake beams in at least two locations. The brake shoes contain a plurality of slanting slots in their braking surfaces for interrupting harmonics producing screeching noises during retardation. The brake shoes may be formed of steel or heat treatable ductile iron.
U.S. Pat. No. 7,140,698, the disclosure of which is hereby incorporated herein by reference in entirety, discloses a hydraulic control and operating system for a railroad car retarder to control the movement of railroad cars in a railroad classification yard. The system utilizes a double-acting hydraulic cylinder to operate the retarder mechanism and includes a hydraulic control circuit that provides protection against pressure spikes and high-pressure excursions, high and low temperature excursions, low oil levels and oil filter fouling. The system shuts itself down to prevent damage and provides a warning to maintenance staff that service should be performed long before a need for system shutdown is required. The system includes a central operating panel in the rail yard control center, a remote-control panel located at the position of the retarder, and the system can be connected for operation from a completely remote location.
U.S. Pat. No. 8,413,770, the disclosure of which is hereby incorporated herein by reference in entirety, discloses systems for and methods of operating electro-hydraulic retarders. In one example, a system is provided for retarding the speed of a railcar. The system includes a brake, a hydraulic actuator coupled to the brake, and a hydraulic circuit that directs pressurized hydraulic fluid to the actuator. The fluid causes the actuator to move the brake towards a closed position in which the brake will apply a predetermined braking pressure on a wheel of the railcar. A hydraulic accumulator is coupled to the hydraulic circuit and configured to accumulate fluid from the hydraulic circuit when the wheel forces the brake out of the closed position and to supply pressurized accumulated fluid back to the hydraulic circuit when the brake moves back into the closed position to thereby maintain a substantially constant braking pressure on the wheel of the railcar as it moves through the brake.
U.S. Pat. No. 8,499,900, the disclosure of which is hereby incorporated herein by reference in entirety, discloses electro-hydraulic retarders designed to allow opposing brake shoes on the retarder to spread to the width of a wheel entering the retarder, and yet still maintain a desired braking pressure on the sides of the wheel. In one example, the retarder includes a brake and a brake actuator that has a piston-cylinder and a spring. One or both of the piston and the cylinder acts on the brake and the other of the piston and the cylinder acts on one end of the spring. The other end of the spring acts on the brake. In one example, the spring is wrapped around the cylinder and connected thereto in series. In such an arrangement, supplying pressurized hydraulic fluid to the piston-cylinder causes both the piston-cylinder and the spring to move the brake towards a closed position in which the brake will apply a predetermined braking pressure on a wheel of the railcar. The spring resiliently biases the brake into the closed position to maintain a substantially constant braking pressure on the wheel of the railcar as it moves through the retarder.
U.S. Patent Application Publication No. 2011/0315491, the disclosure of which is hereby incorporated herein by reference in entirety, discloses systems for retarding the speed of a railcar. In one example, a hydraulic actuator moves a brake between a closed position in which the brake applies braking pressure on a railcar wheel, and an open position in which the brake does not apply braking pressure on the railcar wheel. A pump supplies hydraulic fluid into at least one of a first manifold and a second manifold of a hydraulic circuit. A logic element reacts to maintaining a selected pressure in the first manifold when a railcar wheel enters a brake and moves the brake from the closed position to the open position to cause a selected braking pressure to be applied to the railcar wheel. A control system Controls the logic element to apply the selected braking pressure on the railcar wheel.
SUMMARYThis Summary is provided to introduce a selection of concepts that are further described below in the Detailed Description. This Summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.
One aspect of the present disclosure generally relates to a system for retarding a railcar. They system includes a brake and an actuator that moves the brake between a closed position in which the brake slows the railcar and an open position in which the brake does not slow the railcar. The system further includes a hydraulic circuit through which a hydraulic fluid flows between the actuator, a pump, and a reservoir. A variable speed motor drives the pump to supply the hydraulic fluid from the reservoir to the actuator, the variable speed motor being operable at a plurality of speeds between fully-on and fully-off states. A control system determines a speed setting within the plurality of speeds for operating the variable speed motor based on a pressure of the hydraulic fluid in the hydraulic circuit, the speed setting being determined such that the pressure is sufficient for operating the actuator.
In another aspect, a pressure sensor is fluidly coupled within the hydraulic circuit and configured to measure the pressure of the hydraulic fluid therein.
In another aspect, the control system compares the pressure of the hydraulic fluid in the hydraulic circuit to a table stored in memory for determining the speed setting for operating the motor.
In another aspect, the control system compares the pressure of the hydraulic fluid to an upper setpoint for determining the speed setting, wherein when the pressure of the hydraulic fluid is below the upper setpoint the control system is configured to determine the speed setting inversely proportionally to changes in the pressure of the hydraulic fluid.
In another aspect, the control system compares the pressure of the hydraulic fluid to an upper setpoint for determining the speed setting, wherein the speed setting is greater when the pressure is below the upper setpoint than when the pressure is above the upper setpoint, and wherein the speed setting remains non-zero when the pressure is above the upper setpoint such that the hydraulic fluid continues to flow through the hydraulic circuit.
In another aspect, a fluid quality sensor is operatively coupled within the hydraulic circuit and configured to compare a quality measurement of the hydraulic fluid as measured by the fluid quality sensor to a threshold, wherein the control system is configured to provide a notification when the quality measurement exceeds the threshold. In a further aspect, the quality measurement includes a type of particulate present within the hydraulic fluid, and the notification is based at least in part on the type of particular present within the hydraulic fluid. In a further aspect, the notification includes a recommended action based on the type of particular present to bring the quality measurement below the threshold.
In another aspect, the control system permits a user to manually change the notification, wherein the control system records when the notification is manually changed.
In another aspect, an accumulator is fluidly coupled to the pump, wherein the pump charges the accumulator, and wherein the accumulator is configured to provide powered movement of the brake to the closed position when the pump is de-energized.
In another aspect, the control system and the hydraulic circuit are configured to provide a non-powered movement of the brake from the closed position to the open position without the hydraulic fluid being forced from the actuator and without the hydraulic fluid being supplied to the actuator such that the actuator is in a relaxed position in which the hydraulic fluid from the actuator is given a free path back to the reservoir.
In another aspect, the pump is configured to supply the hydraulic fluid to one end of the actuator to provide a powered movement of the brake to the closed position and to an opposite end of the actuator to provide a powered movement of the brake to the open position.
In another aspect, the control system controls the speed setting of the variable speed motor by adjusting a frequency of voltage delivered thereto.
In another aspect, the variable speed motor is a brushless AC induction motor.
In another aspect, the control system is further configured to control the variable speed motor so as to not exceed at least one of a maximum current, maximum voltage, maximum speed, and maximum rate of speed change.
Another aspect generally relates to a method for slowing a railcar. The method includes configuring a brake to slow the railcar when in a closed position and to not slow the railcar when in an open position, configuring an actuator to move the brake into and between the closed position and the open position, and fluidly coupling the actuator, a reservoir, and a pump to form a hydraulic circuit, the pump being driven by a variable speed motor operable at a plurality of speeds between fully-on and fully-off states to supply hydraulic fluid from the reservoir to the actuator. The method further includes controlling the speed setting of the variable speed motor based on a pressure of the hydraulic fluid in the hydraulic circuit such that the pressure is sufficient to operate the actuator, and operating the actuator to move the brake into the closed position to slow the railcar.
In another aspect, the method further includes determining the pressure of the hydraulic fluid via a pressure sensor fluidly coupled within the hydraulic circuit.
In another aspect, the pressure measured by the pressure sensor is distinct from a braking pressure applied by the brake.
In another aspect, the method further includes fluidly coupling an accumulator within the hydraulic circuit such that the pump charges the accumulator and the accumulator is configured to provide a powered movement of the brake to the closed position when the pump is de-energized.
Another aspect generally relates to a system for controlling a railcar moving along a set of rails. The system includes a member configured to selectively contact wheels of the railcar, and an actuator that moves the member between a closed position in which the member contacts the wheels of the railcar and an open position in which the member does not contact the wheels of the railcar. The system further includes a hydraulic circuit through which a hydraulic fluid flows between the actuator, a pump, and a reservoir. A variable speed motor drives the pump to supply the hydraulic fluid from the reservoir to the actuator, the variable speed motor being operable at a plurality of speeds between fully-on and fully-off states. A pressure sensor is configured to measure a pressure of the hydraulic fluid in the hydraulic circuit. A control system determines a speed setting within the plurality of speeds for operating the variable speed motor based on the pressure of the hydraulic fluid in the hydraulic circuit, the speed setting being determined such that the pressure is sufficient for operating the actuator.
Another aspect of the present disclosure generally relates to a system for retarding a railcar having wheels. The system includes a brake and an actuator configured to move the brake between a closed position in which the brake contacts the wheels of the railcar and an open position in which the brake does not contact the wheels of the railcar. The system further includes a hydraulic circuit through which a hydraulic fluid flows between the actuator and a reservoir. A first pump is operably connected within the hydraulic circuit and configured to provide the hydraulic fluid to the actuator for operating the brake. A heat exchanger is operably connected within the hydraulic circuit and configured to cool the hydraulic fluid flowing therethrough. A second pump is operably connected within the hydraulic circuit and configured to provide the hydraulic fluid to the heat exchanger. The heat exchanger prevents the hydraulic fluid within the hydraulic fluid from exceeding a target operating temperature.
In another aspect, the system further includes a motor, wherein the first pump and the second pump are operated by the motor.
In another aspect, the motor operates the first pump and the second pump simultaneously.
In another aspect, the motor is a variable speed motor operable at a plurality of speeds between fully-on and fully-off states. In a further aspect, the variable speed motor is a brushless AC motor. In a further aspect, the variable speed motor is operable at the plurality of speeds by adjusting a frequency of voltage delivered thereto.
In another aspect, the system further includes a temperature sensor that measure a temperature of the hydraulic fluid within the hydraulic circuit, a value operatively coupled within the hydraulic circuit and configured to change a flow of the hydraulic circuit to the heat exchanger, and a control system operatively coupled to the valve, wherein the control system is configured to control the valve based on the temperature measured by the temperature sensor. In a further aspect, the control system is configured to compare the temperature measured by the temperature sensor to a lower threshold and to bypass the heat exchanger when the temperature is below the lower threshold.
In another aspect, the heat exchanger is a radiator and a fan. In a further aspect, the fan is hydraulically operated via the hydraulic fluid flowing through the hydraulic circuit.
In another aspect, a motor operates at least one of the first pump and the second pump, and further comprising a coolant system in which a coolant flows through a coolant circuit to cool the motor so as to prevent the motor from overheating. In a further aspect, the heat exchanger includes a first radiator and a second radiator, and wherein the first radiator is operatively connected within the hydraulic circuit so as to provide heat exchange for the hydraulic fluid, and wherein the second radiator is operatively connected within the coolant circuit so as to provide heat exchange for the coolant. In a further aspect, the first pump and the second pump are both operated by the motor. In a further aspect, a fan is configured to cool both the first radiator and the second radiator. In a further aspect, the coolant system comprises a pump for circulating the coolant through the coolant circuit, further comprising a temperature sensor that measures a temperature of the coolant within the coolant circuit, and further comprising a control system for operating the pump based on the temperature of the coolant within the coolant circuit.
In another aspect, a motor operates at least one of the first pump and the second pump, and the system further includes an enclosure in which the first pump, the second pump, and the motor are situated for protection. In a further aspect, the enclosure includes a housing and a cover separated from the housing, wherein the cover at least partially shades the housing, and wherein the cover is positioned above the housing such that a gap remains therebetween to provide a thermal buffer between the housing and the cover. In a further aspect, an opening extends through a top of the housing, and the cover is positioned at least over the opening to prevent ingress into the housing from above.
Another aspect generally relates to a method for cooling a system configured for slowing a railcar. The system includes a brake that slows the railcar when in a closed position and does not slow the railcar when in an open position, and the system further including an actuator that moves the brake into and between the closed position and the open position. The method includes fluidly coupling the actuator, a reservoir, and a pump to form a hydraulic circuit, and measuring a temperature of hydraulic fluid within the hydraulic circuit and comparing the temperature to a threshold. The method further includes controlling a valve to cause the hydraulic fluid to flow to a heat exchanger when the temperature of the hydraulic fluid exceeds the threshold, and controlling the valve to cause the hydraulic fluid to bypass the heat exchanger when the temperature of the hydraulic fluid is less than the threshold. The heat exchanger is configured to exchange heat with the hydraulic fluid to prevent the temperature of the hydraulic fluid from exceeding a target operating temperature.
Another aspect generally relates to a method for cooling a system configured for slowing a railcar. The system including a brake that slows the railcar when in a closed position and does not slow the railcar when in an open position, and the system further including an actuator that moves the brake into and between the closed position and the open position. The method includes fluidly coupling the actuator, a reservoir, and a pump operated by a motor to form a hydraulic circuit through which a hydraulic fluid flows, fluidly coupling the motor to a coolant circuit through which a coolant flows, wherein the coolant remains fluidly isolated from the hydraulic fluid, and circulating the coolant through the coolant circuit to prevent the motor overheating during operation of the system for slowing the railcar.
It should be recognized that the different aspects described throughout this disclosure may be combined in different manners, including those than expressly disclosed in the provided examples, while still constituting an invention accord to the present disclosure.
Various other features, objects and advantages of the disclosure will be made apparent from the following description taken together with the drawings.
In the present disclosure, certain terms have been used for brevity, clearness and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes only and are intended to be broadly construed. The different systems and methods described herein may be used alone or in combination with other systems and methods. Various equivalents, alternatives and modifications are possible within the scope of the appended claims.
The present disclosure arises from the present inventors' research and development of electro-hydraulic systems for retarding or slowing the speed of a railcar traveling on a set of rails. The inventors have recognized that more efficient and effective electro-hydraulic retarder systems and methods of operating such systems are needed in the art. The present inventors have recognized advantages to controlling a variable speed motor to drive the hydraulic pump, rather than a single-speed motors as presently known in the art. One advantage is faster pressurization of hydraulic fluid within the system. Another advantage is reducing unnecessary flow of the hydraulic fluid through the system, which reduces wasted energy, reduces heat generated within the system, and improves the reliability and longevity of components by reduced usage.
In use, the hydraulic circuit 32 conveys hydraulic fluid to and from the piston-cylinders 42 and controls the pressure of the hydraulic fluid to move the brake 30 between its closed position and its open position and to apply selected braking pressures to the wheel of the railcar. Specifically, the hydraulic piston-cylinder 42 is movable under hydraulic pressure from the circuit 32 between an extended position, wherein the piston-rod 46 extends from the cylinder 44 to move the brake 30 into the closed position and a retracted position wherein the piston-rod 46 retracts into the cylinder 44 to move the brake 30 into the open position. When it is desired to retard the motion of a railcar riding on rails 24 a Braking State is initiated, hydraulic fluid is provided to one end of the piston-cylinder 42 via the hydraulic circuit 32 to actuate the piston-cylinder 42 to extend piston-rod 46. The piston-cylinder 42 pivots the ends of levers 38, 40 apart, and thus moves the brake shoes 50 towards each other and into contact with a railcar wheel. Brake shoes 50 contact the inside and outside of a railcar wheel riding on the rail to apply a braking pressure. To decrease braking force during the Braking State, the fluid pressure on the end of the piston-cylinder 42 is decreased. To terminate the retarding action the fluid pressure on the end of the piston-cylinder 42 is removed and the return springs 55, 57 and the weight of the upper lever 38 move the ends of levers 38, 40 together and thus move the brake shoes 50 outwardly away from the railcar wheel and into a Relaxed State. The brake shoes 50 can also be moved outwardly away from the railcar wheel and into a Power Open/Flush State by providing hydraulic fluid to an opposite end of the piston-cylinder 42 to actuate the piston-cylinder 42 to retract piston-rod 46.
A non-limiting example of the hydraulic circuit 32 and related components will now be described with reference to drawing
The retarder system 20 also includes a control system C which can be located adjacent to and/or remotely from the retarder system 20. The control system C can include one or more control circuit sections. Each section is generally a computing system that includes a processing system, storage system, software, communication interface, and optionally a user interface. The processing system loads and executes software from the storage system, including a software module. When executed by the computing system, software module directs the processing system to operate as described herein in further detail in accordance with the methods of the present disclosure. While a description as provided herein refers to a computing system and a processing system, it is to be recognized that implementation of such systems can be performed using one or more processors, which may be communicatively connected, and such implementations are considered to be within the scope of the disclosure. The processing system can include a microprocessor and other circuitry that retrieves and executes software from a storage system. Processing systems can be implemented with a single processing device but can also be distributed across multiple processing devices or subsystems that cooperate in executing program instructions. Examples of processing systems includes a general-purpose central processing unit, application specific processor, logic devices, as well as other types of processing devices, combinations of processing devices, or variations thereof. Storage systems can include any storage media readable by a processing system and capable of storing software. The storage system can include volatile and non-volatile, removable and non-removable media implemented in any method or technology for storage of information, such as computer readable instructions, data structures, program modules, or other data. Storage systems can be implemented as a single storage device but may also be implemented across multiple storage devices or subsystems. Storage systems can further include additional elements, such as a controller, capable of communicating with the processing system. Each storage media can include random access memory, read only memory, magnetic disks, optical disks, flash memory disks, virtual and non-virtual memory, magnetic sets, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other media which can be used to store the desired information and that may be accessed by an instruction execution system, as well as any combination or variation thereof, or any other type of storage media. In some implementations, the storage media can be a non-transitory storage media. User interface can include a mouse, a keyboard, a voice input device, a touch input device for receiving a gesture from a user, a motion input device for detecting non-touch gestures and other motions by a user, and other comparable input devices and associated processing elements capable of receiving user input from a user. Output devices such as a video display or a graphical display can display an interface further associated with embodiments of the system and method as disclosed herein.
The control system C is configured to send and receive commands or signals with a location yard monitor system M, such as by means of a detector, radar, laser and the like, to determine the position of a moving railcar in the retarder system 20. As a railcar approaches the retarder system 20, the yard monitor system M monitors environmental factors and/or characteristics of the railcar such as weight, velocity, direction and the like, and calculates an amount of braking pressure necessary to achieve a desired railcar speed, all as is conventional. Based upon the calculation, the control system C is programmed, such as by a programmable logic controller (PLC), to control operations of the various components of the retarder system 20 via one or more wired or wireless links as shown schematically at L to achieve a selected braking pressure. Braking pressure is typically defined in the art in terms of various railcar weight classes.
The control system C is designed to control one or more components of the retarder system 20 to apply, maintain or change a predetermined braking pressure on the railcar wheel(s) as it travels and leaves the retarder system 20 (as determined by the yard monitoring system M). Prior to the wheel(s) entering the retarder system 20, the control system C can control the retarder system 20 to open and/or close the brakes 30 with minimal pressure. Once the railcar is in the retarder system 20, the control system C can quickly change braking pressures applied to the wheel(s) in accordance with the predetermined or active parameters set by the yard monitoring system M and/or entered by an operator into the retarder system 20 via a conventional computer input device (not shown). Each of these functions is accomplished by the programming of the control system C and its communication with components in the retarder system 20 which will be understood by one having ordinary skill in the art.
With further reference to
The accumulator 136 can include any one of a variety of hydraulic energy storage devices, such as compressed gas or a gas-charged accumulator or the like. In the example shown, the accumulator 136 is constructed with two chambers that are separated, for example, by an elastic diaphragm or floating piston. One chamber contains an inert gas under pressure or “pre-charge” that provides compressive force on the hydraulic fluid in the hydraulic circuit 32. Here, the hydraulic circuit 32 is designed so that the primary pump 106 pumps hydraulic fluid to the other chamber of the accumulator 136 for a predetermined time to charge or load the accumulator 136 above its preloaded nitrogen charge (e.g., 2200 psi) until the hydraulic fluid reaches a predetermined maximum system pressure such as, for example, 3000 psi. In this charging phase, hydraulic fluid is prevented from flowing past the manual flow control valve 138 which is normally closed. The manual flow control valve 138 can be opened to ensure that hydraulic fluid in the accumulator 136 is directed back to the reservoir 110 at a regulated rate when the retarder system 20 is shut down. The relief valve 140 is normally closed to prevent any fluid flow therethrough. However, if the pressure of the hydraulic fluid charged in the accumulator 136 exceeds the predetermined maximum system pressure by a certain amount, for example if the charge pressure reaches 3250 psi, the relief valve 140 is shifted open to discharge an appropriate amount of fluid back to the reservoir 110 until the maximum system pressure is satisfied at which time the relief valve 140 is again closed.
As the primary pump 106 charges the accumulator 136 with hydraulic fluid, the system pressure, represented by arrows B in
At this point, the accumulator 136 is fully charged, the motor 104 is turned off, the piston-cylinders 42 associated with the brakes 30 are in a retracted mode and the hydraulic circuit 32 is readied for a braking event in which each piston 62 may be extended as the accumulator 136 is discharged. To close the brakes 30, the control system C sends a signal to energize and shift the pilot control solenoid valve 146 from the closed condition to an open condition. As depicted in
Hydraulic fluid at the selected pressure is then monitored by a pressure transducer 176 (also referred to as a pressure sensor) and delivered through multi-port connectors 178, 180 into the cap-side chamber 66 of each piston-cylinder 42. Hydraulic fluid flowing towards a directional control valve 182 is prevented from flow therethrough by sending a signal to energize solenoid valve 148 causing the directional control valve 182 to close and prevent flow to the reservoir 110. Introduction of hydraulic fluid represented by arrows C into the cap-side chamber 66 forces each piston 62 into an extended position thus forcing the upper and lower levers 38, 40 to pivot about the pin 36 and close the brake shoes 50 relative to one another. Thus, the brake 30 is actuated via a powered movement into a closed condition and the Braking State with a selected braking pressure commensurate to that set by the control system C. During brake closing, the solenoid valves 150 and 158 are de-energized, while solenoid valves 146, 148 and 166 are energized as noted above.
During movement of each piston 62 into its extended position, the hydraulic fluid will act to close a check valve 186 provided on the piston 62 so that there is no fluid transfer through dampening orifices 68 between the rod-side chamber 64 and the cap-side chamber 66. Hydraulic fluid flows out of the rod-side port 58 and, as represented by arrows Cl, is discharged back into the hydraulic circuit 32 thus facilitating movement of the brake 30 to the closed position.
When the brake 30 is in the closed position and with solenoid valves 146, 148 and 166 energized, it is forced into an open position by a railcar wheel traveling into the brake 30 as illustrated in
Referring to
It should be appreciated that at this point, no pressurized hydraulic fluid has been supplied to the rod ports 58 of the piston-cylinders 42. Instead, the hydraulic fluid is given a free path from the cap-side chambers 66 back to reservoir 110 defining a relaxed position for the piston-cylinder 42 in which the weight of the levers 38, 40 and the return springs 55, 57 will cause at least partial opening of the brakes 30 via a non-powered movement. This feature provides for faster brake opening reaction times and makes the retarder system 20 more energy efficient.
Referring to
As a feature of the disclosure, it may be possible to combine hydraulic fluid flows of the primary pump 106 and the secondary pump 108 to move the brakes 30 to their powered open position with decreased cycle times and faster speeds if the accumulator 136 is at full hydraulic charge pressure. When primary pump 106 is available, both the solenoid valve 150 and the flow diverter solenoid valve 158 are energized which results in the shifting of their spools and the combining of the hydraulic fluid flows from the primary pump 106 as represented by arrows G and the secondary pump 108 as represented by arrows F. This combined pump flow is again delivered through the multi-port connectors 208, 210 into the rod-side chambers 64 of the piston-cylinders 42 to effect a faster, more efficient powered movement and opening of the brakes 30.
Referring to
A further feature of the disclosure resides in the provision of certain components 144, 146, 148, 150, 154 (pilot port three), 182 which are designed to provide ultra-low fluid leakage for maintaining accumulator charge. An anti-cavitation check valve 212 connects the low pressure return fluid directly to the rod-side 64 of each piston-cylinder 42. In the event the piston-cylinders 42 are forced open while the motor 104 is off, the check valve 212 allows oil to freely flow from the low pressure return to the rod-side 64 of each piston-cylinder 42 to prevent cylinder cavitation. All return hydraulic fluid is monitored by a temperature sensor 214.
The reservoir 110 is a cyclonic reservoir defined generally by a circular tank that holds the returned hydraulic fluid. The fluid spins and centrifugal forces push the entrained air to the center of the reservoir and the air bubbles will rise past an integrated baffle and naturally aspirate in the upper portion 112 of the reservoir 110. The cyclonic reservoir 110 provides for a more efficient reservoir used in the processing of the returned hydraulic fluid in the hydraulic circuit 32.
Referring to
The present inventors have developed the presently disclosed systems and methods for further improving upon systems known in the rail industry, including managing railcars in a rail yard. For simplicity, the present disclosure principally refers to applications relating to retarder systems for slowing a speed of a railcar. However, it should be recognized that the variable speed motors, pump configurations, hydraulic circuits, cooling systems, and control systems disclosed herein may also be used in other applications, including any in which a member is controlled to selectively contact a railcar, such as a derailer system.
With reference to
The present inventors have recognized that the control systems C known in the art control the motor 104 to operate regardless of the actual need for further pressure within the hydraulic circuit, essentially stopping only when the accumulator 136 storing hydraulic fluid is fully charged. Consequently, much of the hydraulic fluid pumped by the primary gear pump 106 and/or the secondary gear pump 108 from operating the motor 104 is unnecessary. Specifically, the hydraulic fluid is frequently cycled from the cyclonic reservoir 110, through the hydraulic circuit 32, and back to the cyclonic reservoir 110 without being used to move the brakes 30 in either direction. This unnecessary operation of the motor 104 wastes energy, thereby increasing the cost of operating the retarder system 20. This operation also generates additional heat through the retarder system, wasting further energy by increasing the demand on the cooling loop 192 to remove this additional heat. The increased use and additional heat of the motor 104, the primary gear pump 106 and/or the secondary gear pump 108, the cooling loop 192, and other valves and components also reduces the lifespan of these elements. It then follows that this further increases the cost of ownership, decreases reliability, and decreases the uptime between maintenance events.
The prevent inventors have further identified problems with controlling the motor 104 such that it is completely stopped when the accumulator 136 is fully charged. First, there is no movement of the hydraulic fluid through the hydraulic circuit 32 while the motor 104 is stopped. Therefore, the retarder system 20 is not cooled or lubricated during this time, leading to further thermal and mechanical failures. Additionally, starting and stopping the motor 104 causes greater wear and tear on the motor 104 and related electrical components versus continuously operating the motor 104. The same wear may also occur to the primary gear pump 106 and/or the secondary gear pump 108, which are driven by the motor 104. Once again, the result is deteriorated performance from additional mechanical, thermal, and electrical wear on the motor 104, the primary gear pump 106 and/or the secondary gear pump 108, and other components.
In certain configurations, the single speed motor operating speed is dependent on the voltage level of the source. Higher voltages in one retarder system installation location can cause a reduction in motor speed and conversely lower voltages will cause higher speed at the expense of increase current load on the source. This leads to another major variable on equipment performance based on equipment location.
Through experimentation and development, the present inventors have recognized that using a variable speed motor 105, such as a brushless DC or AC induction motor, along with a correspondingly configured control system C, improves the performance and efficiency of the retarder system 21. In addition to improved efficiency and performance, using a brushless motor as the variable speed motor 105 (whether AC or DC) overcomes some the short-comings of the brushed technology, such as brush wear and contamination. In the case of a brushless DC motor as the variable speed motor 105, the control system C controls the frequency of DC voltage provided to the variable speed motor 105 to adjust the speed setting thereof (in other words, to change the RPM of the motor). One example of a variable speed, brushless DC motor available in the market is Model Number BLDC1.5-90, produced by Volcano Electric in Zhejiang, China, the Model Rx30, produced by MGM COMPRO of the Czech Republic, or Tesla® Model 3.
In the case of an AC induction motor as the variable speed motor 105, the control system C includes an AC Variable Frequency Drive (VFD) that controls the frequency of AC voltage provided to the variable speed motor 105 to adjust the speed setting thereof. Examples of AC induction motors that could be used in the present retarder system 21 include the drive motors commonly used in electric cars, for example the Marathon Motors with Rockwell Automation Allen Bradley PowerFlex.
A conventional VFD includes three separate sections. The first section includes a convertor that converts AC power to DC power. The second section includes DC-based circuitry such as a capacitor and inductor to provide filtering, which ensures delivery of a smooth, rectified DC voltage. The third section includes a DC-to-AC inverter that converts the DC power back to three-phase AC power (or a pulse width representation of three phases). In short, the inverter rapidly switches the DC power on and off so that the variable speed motor 105 receives a pulsating voltage that is like AC power. The switching rate is controllable by the control system C to vary the frequency of the simulated AC that is applied to the variable speed motor 105.
Using an AC induction motor as the variable speed motor 105 requires that the applied voltage be proportionally adjusted whenever the frequency is changed. In other words, if a motor is designed to operate at 460 Volts at 60 Hz, the applied voltage must be reduced to 230 Volts when the frequency is reduced to 30 Hz. Therefore, the ratio of volts over hertz must be regulated to a constant value (460/60=7.67 in this case). The control system C or VFD may use pulse width modulation (PWM) for adjusting the voltage in proportion to changes in the frequency of the power delivered to the variable speed motor 105. With PWM voltage control, inverter switches are used to divide the simulated sine-wave output waveform into a series of narrow voltage pulses with modulated width of the pulses, which are created by rapidly turning on and off the DC voltage. Therefore, the control system C delivers both a varying voltage and a varying frequency to the variable speed motor 105 to adjust the speed setting thereof. The higher the frequency supplied to the variable speed motor 105, the faster it will run.
It should be recognized that the same principals can also be used to vary the torque and/or horsepower of the variable speed motor 105. Moreover, the present inventors have recognized that using these techniques, the control system C can control the variable speed motor 105 to operate at speed settings outside the rated range of speeds (above and/or below).
One advantage of using a brushless DC motor as the variable speed motor 105 is the ability to implement a permanent magnetic rotor field, as opposed to an induced rotor filed found in an AC induction motor. The permanent magnet rotor field allows the motor to rotate with a significantly less energy, particularly as the motor does not need to compensate for loses (e.g., iron losses) to generate a rotational field as required by an AC induction motor. This provides higher power densities without increasing the required input energy. However, there are also advantages to AC motors and thus both are contemplated for use.
The present inventors have recognized that maximizing the output energy of the variable speed motor 105 with the least amount of input energy requires tracking the position of the rotors therein. For this purpose, hall-effect sensors are mounted in the variable speed motor 105, which send signals to the control system C to provide rotor position feedback. Using this position feedback, the inverter sends power into the windings of the variable speed motor 105 to cause rotation. The control system C uses the hall effect sensors feedback to coordinate the turning on and off of IGBT switches to rotate the motor rotor (a process also referred to as commutation).
Commutation for either a brushless DC motor or an AC induction motor is a six-step process. A three-Phase H-Bridge is used to create six flow vectors each causing a rotation of 60 degrees relative to each position of the rotor, thus making a full rotation of 360 degrees. The rate that these vectors change controls the speed of the variable speed motor 105, which changes the pulse width of power from the control system C. The control system C generates a simulated sine wave using pulses of energy with varying widths to build this wave. When the flow vectors lag behind the commanded speed, the vectors increase the width of each pulse to release more energy to the variable speed motor 105 winding. The changes in width continue until the variable speed motor 105 is achieves the speed setting desired. Conversely, the control system C narrows the widths of the pulses to reduce the speed setting of the variable speed motor 105. The vectors are used to control the energy delivered to the variable speed motor 105 based on the load that is applied to the rotor. In focus these vectors represent torque. The greater the vector angle, the wider PWM signal, and the more torque that will be generated. In particular, the wider PWM signal causes more current to flow to the motor windings, which generates more flux to thus generate the increased torque.
It should be recognized that portions of the control system C, such as the VFD, may be provided onboard the variable speed motor 105 itself. It should further be recognized that the same type of control system C may be used for either a brushless DC motor or an AC induction motor, for example, with the control system C being powered via DC power.
With reference to
In certain examples, the control system C communicates with each of the one or more components of the retarder system 21 via a communication link CL, which can be any wired or wireless link L as discussed above. The communication link CL may be a controller area network (CAN) bus; however, other types of links could be used. It will be recognized that the extent of connections and the communication links CL may in fact be one or more shared connections, or links, among some or all of the components in the retarder system 21. Moreover, the communication link CL lines are meant only to demonstrate that the various control elements are capable of communicating with one another, and do not represent actual wiring connections between the various elements, nor do they represent the only paths of communication between the elements. Additionally, the retarder system 21 may incorporate various types of communication devices and systems, and thus the illustrated communication links CL may in fact represent various different types of wireless and/or wired data communication systems.
The control system C includes a processing system CS110, memory system CS120, and input/output (I/O) system CS130 for communicating with other devices, such as the input devices CS99, the output devices CS101, and/or a cloud-based computing system CS102. The processing system CS110 loads and executes an executable program CS122 from the memory system CS120, accesses data CS124 stored within the memory system CS120, and directs the retarder system 21 to operate as described herein.
The processing system CS110 may be implemented as a single microprocessor or other circuitry or be distributed across multiple processing devices or sub-systems that cooperate to execute the executable program CS122 from the memory system CS120. Non-limiting examples of the processing system include general purpose central processing units, application specific processors, and logic devices. The memory system CS120 may comprise any storage media readable by the processing system CS110 and capable of storing the executable program CS122 and/or data CS124. The memory system CS120 may be implemented as a single storage device or be distributed across multiple storage devices or sub-systems that cooperate to store computer readable instructions, data structures, program modules, or other data. The memory system CS120 may include volatile and/or non-volatile systems and may include removable and/or non-removable media implemented in any method or technology for storage of information. The storage media may include non-transitory and/or transitory storage media, including random access memory, read only memory, magnetic discs, optical discs, flash memory, virtual memory, and non-virtual memory, magnetic storage devices, or any other medium which can be used to store information and be accessed by an instruction execution system, for example.
Returning to
With reference to
In certain configurations, the control system C reduces the speed setting for operating the variable speed motor 105 inversely proportionally to changes in the pressure. For example, the speed setting may be reduced from the maximum speed at a rate of 10 RPM for every 20 PSI increase in pressure within the hydraulic circuit 32 while the pressure is below 3000 PSI. The present disclosure also contemplates other control schemes for determining the speed setting as a function of the pressure of hydraulic pressure, including other proportions (e.g., 30 RPM for every 20 PSI), exponential relationships, step-wise adjustments, or other functions.
By reducing the speed setting of the variable speed motor 105, the control system C decreases the flow of hydraulic fluid in the hydraulic circuit 32 as the pressure increases. In certain embodiments, an upper setpoint CS127 of pressure is stored in memory system CS120 and referenced by the control system C such that the flow of hydraulic fluid is reduced as the pressure in the hydraulic circuit 32 approaches this upper setpoint. Likewise, the control system C is also configured to increase the flow of hydraulic fluid as the pressure gets further below the upper setpoint CS127 pressure. A lower setpoint CS128 may also be stored in the memory system CS120, whereby the speed setting is adjusted to be greater when the pressure is below the lower setpoint CS128 as compared to other values (e.g., the speed setting has a step increase and/or is adjusted according to a different function CS126 at the lower setpoint CS128). The control system C therefore actively manages the pressure within the hydraulic circuit 32 such that the pressure is sufficient to move the brakes 30 as needed, but to not create waste beyond this need.
The present inventors have recognized that by controlling the flow of hydraulic fluid to actively manage the pressure of hydraulic fluid within a set range, other components necessary for retarder systems with single-speed motors can be eliminated. These components include the accumulator 136, which helps manage pressure in the hydraulic circuit 32 as well as the ball valve 134 and other elements that are needed with the accumulator 136 (see
In addition to adjusting the speed setting of the variable speed motor 105, the control system C may limit the rate at which this speed setting is changed (e.g., a maximum ramp-up and/or ramp-down rates for the variable speed motor 105). By way of example, the control system C may be limited to increasing the speed setting no more than 10 RPM per second or 10% per second (based on the maximum RPM, a current RPM, or another preset RPM). Likewise, the control system C may limit decreases to the speed setting to not be greater than 50 RPM per second or 20% per second. The control system C may also control the speed and pressure of braking, provide a power boost during ramp-up, and/or provide a variety of controls during ramp-down. A power boost is available during ramp-up because the controller at this point has the ability to provide more current and more power than the rated nameplate of the motor. This makes the motor provide more power output than nominally available, but is limited by the available input current (which the control system C monitors and controls). In the ramp down, the controller can control the rate at which power is reduced, preventing the DC portions of the control system C from increasing the voltage too quickly. Moreover, if the DC voltage does become too high, the control system C is configured to dump voltage to a resistor.
Step 310 provides for configuring a control circuit to receive a pressure of the hydraulic fluid in the hydraulic circuit. In step 312, a speed setting is determined from among the plurality of speeds to operate the motor based on the pressure of the hydraulic fluid in the hydraulic circuit. The speed setting determination may be made via application of an algorithm, reference to a lookup table, and/or the like in which the pressure is an input and the output is a speed setting for operating the variable speed motor 105. Step 314 provides for operating the motor to move the brake into and between the closed position and the open position and operating the motor at the speed setting to control a flow of the hydraulic fluid based on the pressure of the hydraulic fluid in the hydraulic circuit.
Alternatively, if in step 514 it is determined that the pressures exceed the upper setpoint 501, step 520 provides for determining a speed setting that is a low, non-zero speed setting. With reference to the example provided above with first and second RPMs for operating a step-wise function, this low, non-zero speed setting may be the same step or a further step distinct from the second RPM above. This low, non-zero speed setting need not be the same as the minimum speed for operating the variable speed motor. In one example, the low, non-zero speed setting of step 520 is 8% of the maximum speed, whereas the minimum speed is less (e.g., 5% of the maximum speed). Following the determination of speed setting in either step 516 or step 520, step 518 proceeds in the substantially same manner as step 314 of
In certain embodiments, the pump arrangement limits 603 may include a maximum speed for operating the pump arrangement. The control system C may control the operation of the pump arrangement via a known correlation to the speed setting of the variable speed motor driving it (e.g., the pump arrangement rotating at a rate 1.3 times greater than the variable speed motor). This maximum speed for operating the pump arrangement (and/or the variable speed motor) need not be constant, factoring in additional variables such as the pressure in the hydraulic circuit, whether the brakes are moving (and in which direction), and/or temperature measurements of the pump arrangement or other components. These same examples also apply to the motor limits 605, which may also include maximum voltages, currents, or speeds that limit the determination of speed setting to preserve the safety and longevity of the motor. For example, the motor limits 605 may not permit a change in the speed setting or greater than 10 RPM per second, requiring adjustments to the speed setting to not exceed these further motor limits 605.
Another embodiment of a system 700 for providing hydraulic fluid for retarding or otherwise engaging with a railcar is shown in
With reference to
In the illustrated system 700, the first pump 704 is a modified axial piston pump having two or more displacements (also referred to as flow rates) that are selectable by a digital directional control valve 794, as discussed further below. An example of a commercially available pump usable as the first pump is produced by Parker Hannifin of Cleveland, OH, part number GVM210-200. The first pump 704 has a manifold that regulates the control pressure and provides case flushing oil (hydraulic fluid) to lubricate and cool the internal components of the first pump 104. In this manner, it should be recognized that both the motor 702 may have variable speed operation and the first pump 704 may have variable output or displacement, each being controllable by the control system C to provide the necessary pressures and flows described throughout this disclosure.
The second pump 706 is a double vane cooling pump, whereby the two vanes can also be referred to corresponding to separate pumps 707A, 707B. One commercially available pump suitable for use as the second pump is produced by Metaris of Chesterfield, MI, part number V2010. The second pump 706 has common inlet that provides hydraulic fluid to both of the separate pumps 707A, 707B, as well as a flow control and relief valve cover on the rear section. The front section of the second pump 706 (i.e., separate pump 707B of
Both the first pump 704 and the second pump 706 are operated simultaneously by rotation of the same motor 702. In addition to reducing the bill of materials, operating both pumps via a shared motor 702 saves space and requires fewer power leads. In certain configurations, separate pumps 707A, 707B of the second pump 706 may each provide a flow rate ranging from between 1 and 20, 2 and 10, or 3 and 8 gallons per minute. It should be recognized that when operated by a variable speed motor as the motor 702, this flow rate will vary as a function of the speed setting of the motor 702.
With continued reference to
In this manner, the hydraulic fluid flows from the manifold 724 to the actuators to move the brakes via ball valves 726A and 727A and back to the manifold 724 via ball valves 726B and 727B. The manifold 724 is further connected via a hose 722 to return the hydraulic fluid to the tank 720. In the illustrated embodiment, a hydraulic diffuser 752 is positioned within the tank 720. The hydraulic fluid from the hose 722 flows through the hydraulic diffuser 752 before entering the tank 720, which helps to dissipate the hydraulic fluid to prevent or reduce air bubbles or turbulence from being introduced into the tank 720. This may be particularly important during a high speed open or close of the retarder. An example of a commercially available hydraulic diffuser is Lenz Inc. of Dayton, OH's part number LTMAD-50. The tank 720 also includes an internal baffle 721 that generally bisects the interior of the tank, but allows for a small amount of flow across (here, under) the baffle 721 to provide even volume and pressure within the tank 720. The prevent inventors have identified that the baffle 721 advantageously prevents turbulence and vortex effects in which air is sucked into the hydraulic fluid where the hydraulic fluid exits the tank 720. The tank 720 also includes a filler breather 760 that allows the tank to breath as well as filters out any airborne contaminants from the outside. The filler breather may also include a desiccant.
The hydraulic fluid from the tank 720 is returned to the first pump 704 via a hose 732. A ball valve 734 is connected to the hose 732 so as to close off the pathway for the hydraulic fluid to flow from the tank 720 to the first pump 704 via the hose 732. This is advantageous for performing service and maintenance on the system 700, such as to replace the first pump 704 or components thereof.
With continued reference to
The heat exchanger 714 is configured to exchange heat with the hydraulic fluid. If the hydraulic fluid is at a temperature of 110° F. or greater, hydraulic fluid will travel to the heat exchanger. If the hydraulic fluid in less than 110° F., it will bypass the heat exchanger and flow back to the hydraulic oil tank. In the illustrated system 700 of
In the illustrated system 700, the fan 715 itself is hydraulically operated, being fluidly connected within the hydraulic circuit 701 via hoses 746, 748. The present inventors have identified this configuration to be particularly efficient and reliable. However, it should be recognized that other types of fans are also contemplated by the present disclosure, including those operated by a separate electric motor. Additionally, the illustrated system 700 is configured such that the same fan 715 draws heat away from both the first radiator 717A and the second radiator 717B (the second radiator 717B being discussed further below). However, it should be recognized that other configurations are contemplated by the present disclosure, including having separate fans for the two radiators, and/or using other cooling mechanisms known in the art.
The hydraulic fluid exits the heat exchanger 714, and particularly the first radiator 717A to return to the tank 720 via a hose 716. A filter 718 is fluidly connected to the hose 716 such that the hydraulic fluid must flow therethrough before entering the tank 720. The filter 718 may be of a type known in the art for use with hydraulic fluid, which prevents or reduces impurities being introduced into the tank 720. In certain embodiments, the filter 718 includes an electrical indicator that detects when the element has reached its end of life, and a breather which allows the tank to breathe when the hydraulic fluid level changes during cylinder extension and retraction. In addition to allowing the reservoir to breathe, the breather includes media that allows moisture vapors to escape the reservoir, but blocks them from entering the reservoir. The filter 718 may have a 3 micron absolute rating, built in by-pass valve, and have an inside to outside flow path to allow the element to not only filter the oil, but also to act as a diffuser.
The second pump 706 is also fluidly connected back to the tank 720 via a hose 740. The hose 740 acts as a pressure compensator or pump drain for the hydraulic system 700.
The second pump 706 is also fluidly connected to the fan 715 as discussed above. In particular, a hose 748 returns hydraulic fluid from the fan 715 to the second pump 706. The hydraulic fluid is provided to the fan 715 (via the hose 746) from a de-stroke block 762 coupled to the first pump 704. Exemplary pump and de-stroke block assemblies are produced by Power Systems AHS, LLC of Chanhassen, MN (part number PS-02501-VVA-20) and Parker Hannifin (part number MSG30-3245).
With continued reference to
The de-stroke block 762 is directly coupled to the first pump 704 such the first pump 704 pumps a portion of the hydraulic fluid into the de-stroke block 762 when rotated by the motor 102. The de-stroke block 762 has multiple outlets therefrom. The de-stroke block 762 is connected back to the pump 704 via a hose 750 such that the hydraulic fluid flushes the pump 704, such as flushing impurities away from any pistons, valves, vanes, or other components within the pump 704. The first pump 704 is further connected to the tank 720 via a hose 742 to drain the hydraulic fluid used for flushing back to the tank 720, again with any ferrous impurities being caught by the magnet assembly 754 being near the inlet of the tank 720 where this hydraulic fluid is returned. A hose 744 also serves as a drain and exhaust for the de-stroke-block 762, leading back to the tank 720.
The de-stroke block 762 is also fluidly connected to the manifold 724 discussed above via a hose 728. This hose 728 is used to control the flow rate of the first pump 704, particularly by providing a pilot pressure that controls the position of a swash plate within the first pump 704, which is discussed further below. Also relating to the pilot side of the pressures provided within the system 700, the first pump 704 is fluidly connected to the manifold 724 via a hose 730. The hose 730 provides hydraulic fluid on the pilot side of the manifold 724 to ensure even pilot pressure throughout the entire range of operation for the system 700 (e.g., preventing pressure drops during braking events). The hydraulic fluid received within the manifold 724 from the hose 730 flows through a pressure compensated valve stack 802 having solenoids 801A and 801B operable to control the flow through a valve 803 fluidly connected to the manifold 724, which may be a D03 valve such as Danfoss of Denmark's part number DG4V-3-0A-M-U-G7-60. The hydraulic fluid then flows from the valve 803 via the hose 728 to the de-stroke block 762 for controlling the flow rate of the first pump 704, as discussed above. A relief valve 814 is also provided to ensure that the pilot pressure provided through the pressure compensated valve stack 802 does not exceed a maximum threshold, such as 300 PSI.
With reference to
The manifold 724 further includes a series of test ports (e.g., ports 767A in
In addition to providing test ports, the present inventors have recognized that it is advantageous to provide lifting eyes 725 for the manifold 724, which when made of ductile iron may be upwards of 200 pounds with cartridges, valves, and the like installed.
Returning to
The shaft 772 extends entirely through the first pump 704 with the second end 776 engaging a correspondingly splined first end 788 of the shaft 790 rotating within the second pump 706. In the illustrated example, the second pump 706 has two vanes 792 and thus also functions like separate pumps 707A, 707B. The two vanes 792 may be rotationally fixed together to form part of the shaft 790. In the hydraulic circuit 701 discussed above, one of the two vanes 792 maintains the pressure within the pilot side of the manifold 724 (
Additional information is now provided regarding one exemplary manifold 724 for use within the system 700 according to the present disclosure. In general, the manifold 724 controls the direction of the hydraulic fluid traveling within the hydraulic circuit 701 and also regulates the maximum pressure to be provided for the retarder. The manifold 724 has 3 positions to extend and retract the cylinders to slow the railcar in the manner described above. The center position of the valve provides for the flow of hydraulic fluid from the first pump 704 flow to unload at idle times, and also provides a means of releasing all stored pressure in the retarder in the event of e-stop condition or lock out and tag out.
The pressure to the retarder is regulated by the manifold 724 (within a tolerance) in at least three modes. During a first mode providing high flow and low pressure mode, the first pump 704 is operated at a maximum flow (e.g., approximately 70 gallons per minute) and minimum pressure (e.g., less than 150 PSI). In this first mode, one of the solenoid 801A and the solenoid 801B of the valve 803 is energized, whereby the valve 810 determines the pressure setting. The pressure setting of the valve 808 and the valve 810 may be higher than for the solenoid 801 to ensure no interference with the pressure setting for the solenoid 801.
A second mode provides for low flow and low pressure, whereby the first pump 704 is operated at the minimum flow (e.g., approximately 2-3 gallons per minute) and minimum pressure (e.g., less than 150 PSI). Either the solenoid 801A or solenoid 801B is energized, the valve 810 is set to a pressure of 400 PSI, and the valve 808 is set to a pressure of 300 PSI.
A third mode provides for low flow and high pressure, whereby the first pump 704 is operated at the minimum flow (e.g., approximately 2-3 gallons per minute) and high pressure (e.g., above 150 PSI). Both the solenoid 801A and the solenoid 801B are de-energized and the pressure of the valve 810 is set 100 PSI higher than the pressure of the valve 808, by way of example. This higher pressure in the valve 810 pilots a large logic element (e.g., a Vent to Open Logic Valve such as Eaton's part number DPS2-20-V-F-0-40) to form a high flow relief valve. This limits the amount of pressure overshoot that occurs when a load induced pressure spike occurs within the hydraulic circuit 701.
Referring to
A pump 904 draws the coolant from the tank 902 via a hose 906. The pump 904 is driven by a motor 908, such as a 24 VDC electric motor (powered by a correspond type and size of power supply 909). The motor 908 includes a controller 910 that communicates (e.g., via CanOpen bus) within the control system C (
The pump 904 pumps the coolant to the motor drive 703 via a hose 914, which flows through conduits in the motor drive 703 to provide cooling thereto. The coolant then flows to the motor 702 via a hose 916, which then flows through conduits in the motor 702 to provide cooling thereto. The coolant then flows via a hose 918 to the second radiator 717B of the heat exchanger 714, exchanging heat therewith. The fan 715 provides for additional heat removal from the coolant as it flows through the second radiator 717B. The coolant then flows back to the tank 902 via a hose 920 to continue the loop again.
With reference to
The control system C may also be configured to provide for retarder state or pressure logic, which is the logic to determine if the retarder is open or closed and the desired pressure setting to effectuate these positions as demanded. This logic may also include code to auto-correct the pressure setting to maintain a desired tolerance.
The control system C may also be configured to provide for control of the coolant system 700, such as speed setting for the pump 904. The speed setting may be based on temperature feedback from within the coolant circuit 901, such as the thermistor 912 or other temperature sensors within the motor 702 and/or the motor drive 703.
The control system C may also be configured to provide for predictive maintenance calculations. By way of example, this includes determining end-of-life calculations for the various components described herein, including the motor 702, the first pump 704, the second pump 706, or the motor 908, for example. In another example, the control system C uses sensor data to determine when the hydraulic fluid or a filter (e.g., hydraulic, glycol, and/or air) needs to be replaced.
Returning to
The display device 930 is configured to not only display the various conditions discussed above, but also guidance for how to resolve or prevent any issues identified by the control system C based on these conditions. For example, a low pressure measurement in one portion of the hydraulic circuit may indicate one component failing, whereas a low pressure measurement elsewhere may indicate a different component failing. The display device 930 notifies the user of this condition (e.g., low pressure in a particular location) and also that the component of interest should be checked.
In certain embodiments, a warning appears on the display device 930 (which may be accompanied by a buzzing sound), requiring the user to resolve the issue and/or press a “clear” button on the touch screen to stop the warning. The control system C may record these warning and clearing events so as to provide insights for when the user clears a warning without taking the appropriate corrective measures, which may have implications for future troubleshooting or warranty coverage.
A front panel 1324 of the housing 1316 is also pivotable (via hinges 1326) relative to the remainder of the housing 1316 to provide improved access within the enclosure 1300. By way of example, the front panel 1324 may be pivoted downwardly for installation, inspection, and maintenance of the manifold 724 (
A sectional view of one embodiment of the lid 1318 is shown in
The lid 1318 further includes a cover 1350 that is attached to the lower frame 1336 via a series of standoffs 1352, which may be plastic or rubber blocks connected via fasteners 1354 such as screws or bolts, adhesives, or other known methods. The standoffs 1352 provide that the cover 1350 is separated in the height H direction from the housing 1316, and here also from the lower frame 1336 of the lid 1318. In other words, the lid 1318 is configured such that a gap 1356 remains between the cover 1350 and the housing 1316.
For the lid 1318 illustrated to
To further improve airflow, including the escape of heat from inside the enclosure 1300, a central portion 1368 extends upwardly from the lower plate 1360 of the cover 1350. The central portion 1368 includes angled plates 1370 that extend at an angle upwardly from the lower plate 1360 and are connected via an upper plate 1372. The angled plates 1370 and the angled plates 1362 may extend at approximately the same angle as each other (e.g., 45 degrees relative to the vertical direction), and the lower plate 1360 and the upper plate 1370 may each extend at approximately the same angle as each other (here being approximately parallel to the horizontal plane). The illustrated configuration provides for an increased volume of a cavity 1373 below the central portion 1368 of the cover 1350, which improves the airflow 1374 from inside the enclosure 1300 outwardly, particularly in recognition of hot air rising.
By configuring the enclosure 1300 in this manner, the cover 1350 at least partially shades the housing 1316 of the enclosure 1300 from direct sunlight. In other words, the gap between the cover 1350 and the upper plate 1334 of the lid 1318 provides a thermal buffer for the housing 1316. Through experimentation and development, the present inventors have found that the cover 1350 acting as a sunshade can result in the cover 1350 and the upper plate 1334 of the lower frame 1336 having a temperature difference of 15-20° F. This greatly reduces the temperature within the enclosure, improving the lifespan of components therein and reducing the load for the systems involved in keeping them cool.
Additionally, the positioning of the cover 1350 relative to the housing 1316, including the opening 1335 that communicates air and heat through the upper plate 1334, prevents ingress into the housing 1316 from above, as discussed above.
As shown in
The systems and methods described herein therefore provide improved efficiency, performance, and reliability over retarder systems presently known in the art, particularly by managing the pressure of the hydraulic fluid via active control of a variable speed motor and/or cooling such as system.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to make and use the invention. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
Claims
1. A system for retarding a railcar, the system comprising:
- a brake;
- an actuator that moves the brake between a closed position in which the brake slows the railcar and an open position in which the brake does not slow the railcar;
- a hydraulic circuit through which a hydraulic fluid flows between the actuator, a pump, and a reservoir;
- a variable speed motor that drives the pump to supply the hydraulic fluid from the reservoir to the actuator, the variable speed motor being operable at a plurality of speeds between fully-on and fully-off states; and
- a control system that determines a speed setting within the plurality of speeds for operating the variable speed motor based on a pressure of the hydraulic fluid in the hydraulic circuit, the speed setting being determined such that the pressure is sufficient for operating the actuator.
2. The system according to claim 1, further comprising a pressure sensor fluidly coupled within the hydraulic circuit and configured to measure the pressure of the hydraulic fluid therein.
3. The system according to claim 2, wherein the control system compares the pressure of the hydraulic fluid in the hydraulic circuit to a table stored in memory for determining the speed setting for operating the motor.
4. The system according to claim 2, wherein the control system compares the pressure of the hydraulic fluid to an upper setpoint for determining the speed setting, and wherein when the pressure of the hydraulic fluid is below the upper setpoint the control system is configured to determine the speed setting inversely proportionally to changes in the pressure of the hydraulic fluid.
5. The system according to claim 2, wherein the control system compares the pressure of the hydraulic fluid to an upper setpoint for determining the speed setting, wherein the speed setting is greater when the pressure is below the upper setpoint than when the pressure is above the upper setpoint, and wherein the speed setting remains non-zero when the pressure is above the upper setpoint such that the hydraulic fluid continues to flow through the hydraulic circuit.
6. The system according to claim 1, further comprising a fluid quality sensor operatively coupled within the hydraulic circuit and configured to compare a quality measurement of the hydraulic fluid as measured by the fluid quality sensor to a threshold, wherein the control system is configured to provide a notification when the quality measurement exceeds the threshold.
7. The system according to claim 6, wherein the quality measurement comprises a type of particulate present within the hydraulic fluid, and wherein the notification is based at least in part on the type of particular present within the hydraulic fluid.
8. The system according to claim 7, wherein the notification includes a recommended action based on the type of particular present to bring the quality measurement below the threshold.
9. The system according to claim 6, wherein the control system permits a user to manually change the notification, and wherein the control system records when the notification is manually changed.
10. The system according to claim 1, further comprising an accumulator fluidly coupled to the pump, wherein the pump charges the accumulator, and wherein the accumulator is configured to provide powered movement of the brake to the closed position when the pump is de-energized.
11. The system according to claim 1, wherein the control system and the hydraulic circuit are configured to provide a non-powered movement of the brake from the closed position to the open position without the hydraulic fluid being forced from the actuator and without the hydraulic fluid being supplied to the actuator such that the actuator is in a relaxed position in which the hydraulic fluid from the actuator is given a free path back to the reservoir.
12. The system according to claim 1, wherein the pump is configured to supply the hydraulic fluid to one end of the actuator to provide a powered movement of the brake to the closed position and to an opposite end of the actuator to provide a powered movement of the brake to the open position.
13. The system according to claim 1, wherein the control system controls the speed setting of the variable speed motor by adjusting a frequency of voltage delivered thereto.
14. The system according to claim 1, wherein the variable speed motor is a brushless AC induction motor.
15. The system according to claim 1, wherein the control system is further configured to control the variable speed motor so as to not exceed at least one of a maximum current, maximum voltage, maximum speed, and maximum rate of speed change.
16. A method for slowing a railcar, the method comprising:
- configuring a brake to slow the railcar when in a closed position and to not slow the railcar when in an open position;
- configuring an actuator to move the brake into and between the closed position and the open position;
- fluidly coupling the actuator, a reservoir, and a pump to form a hydraulic circuit, the pump being driven by a variable speed motor operable at a plurality of speeds between fully-on and fully-off states to supply hydraulic fluid from the reservoir to the actuator;
- controlling the speed setting of the variable speed motor based on a pressure of the hydraulic fluid in the hydraulic circuit such that the pressure is sufficient to operate the actuator; and
- operating the actuator to move the brake into the closed position to slow the railcar.
17. The method according to claim 16, further comprising determining the pressure of the hydraulic fluid via a pressure sensor fluidly coupled within the hydraulic circuit.
18. The method according to claim 17, wherein the pressure measured by the pressure sensor is distinct from a braking pressure applied by the brake.
19. The method according to claim 16, further comprising fluidly coupling an accumulator within the hydraulic circuit such that the pump charges the accumulator and the accumulator is configured to provide a powered movement of the brake to the closed position when the pump is de-energized.
20. A system for controlling a railcar moving along a set of rails, the system comprising:
- a member configured to selectively contact wheels of the railcar;
- an actuator that moves the member between a closed position in which the member contacts the wheels of the railcar and an open position in which the member does not contact the wheels of the railcar;
- a hydraulic circuit through which a hydraulic fluid flows between the actuator, a pump, and a reservoir;
- a variable speed motor that drives the pump to supply the hydraulic fluid from the reservoir to the actuator, the variable speed motor being operable at a plurality of speeds between fully-on and fully-off states;
- a pressure sensor configured to measure a pressure of the hydraulic fluid in the hydraulic circuit; and
- a control system that determines a speed setting within the plurality of speeds for operating the variable speed motor based on the pressure of the hydraulic fluid in the hydraulic circuit, the speed setting being determined such that the pressure is sufficient for operating the actuator.
Type: Application
Filed: Mar 22, 2023
Publication Date: Oct 19, 2023
Applicant: Precision Rail and Mfg., Inc. (Oak Creek, WI)
Inventors: James D. Braatz (Oak Creek, WI), Ryan Flitsch (Salem Lakes, WI), Joshua Stockton (Pleasant Prairie, WI), David Dworschack (Oak Creek, WI)
Application Number: 18/188,149
