FUEL SYSTEM FOR A VEHICLE
A natural gas system for a vehicle includes a fuel pod, a conduit defining a flow path, a fuel control module, and an accumulator. The fuel pod includes a fuel tank configured to store natural gas. The conduit includes a first end coupled to the fuel pod and a second end configured to be coupled to an engine. The fuel control module is disposed along the flow path and configured to regulate a flow of natural gas to the engine. The accumulator is disposed along the flow path downstream of the fuel control module. The accumulator is configured to buffer variations in the flow of natural gas such that the engine receives a consistent flow of natural gas.
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This application is a continuation of U.S. application Ser. No. 14/098,143, filed Dec. 5, 2013, which is incorporated herein by reference in its entirety.
BACKGROUNDRefuse vehicles collect a wide variety of waste, trash, and other material from residences and businesses. Operators use the refuse vehicle to transport the material from various waste receptacles within a municipality to a storage or processing facility (e.g., a landfill, an incineration facility, a recycling facility, etc.). Refuse vehicles may be powered by an internal combustion engine that burns gasoline, diesel fuel, or natural gas, among other types of fuel. Where the fuel is natural gas, various tanks provide fuel to a regulator, which reduces the pressure of the natural gas before it enters the engine. Mechanical regulators provide an inconsistent flow of natural gas that varies based upon the pressure of the fuel in the natural gas tanks. The natural gas tanks may be positioned above the roof of the body assembly. To isolate the natural gas tanks, an operator boards the refuse vehicle and engages valves positioned at the head of each tank. Despite these deficiencies, assemblies that provide variations in the natural gas flow and include tanks that must be individually isolated remain the primary fuel systems for natural gas powered refuse vehicles.
SUMMARYOne embodiment of the invention relates to a natural gas system for a vehicle that includes a fuel pod, a conduit defining a flow path, a fuel control module, and an accumulator. The fuel pod includes a fuel tank configured to store natural gas. The conduit includes a first end coupled to the fuel pod and a second end configured to be coupled to an engine. The fuel control module is disposed along the flow path and configured to regulate a flow of natural gas to the engine. The accumulator is disposed along the flow path downstream of the fuel control module. The accumulator is configured to buffer variations in the flow of natural gas such that the engine receives a consistent flow of natural gas.
Another embodiment of the invention relates to a vehicle that includes an engine, a tank configured to provide a supply flow of natural gas, a first conduit including a first end coupled to the tank, a valve coupled to a second end of the first conduit, a second conduit defining a low pressure flow path, a pressure transducer disposed along the second conduit, a sensor configured to provide information relating to a requested throttle input associated with the engine, and a controller. The first conduit is a high pressure flow path that extends continuously and directly from the tank to the valve, and the valve is configured to provide a regulated flow of natural gas to the engine by adjusting the supply flow of natural gas. The second conduit includes a first end coupled to the valve and a second end configured to be coupled to the engine. The pressure transducer is configured to provide sensor signals relating to a pressure of the regulated flow of natural gas. The controller is configured to monitor the sensor signals for a fluctuation in the regulated flow of natural gas, evaluate a target pressure for the regulated flow of natural gas based on the fluctuation and the information from the sensor, and selectively engage the valve such that the engine receives natural gas at the target pressure.
Still another embodiment of the invention relates to a vehicle that includes a chassis, a body assembly, and a natural gas fuel system. The chassis includes an engine coupled to a frame. The body assembly is coupled to the frame and includes a plurality of sidewalls and an upper wall. The natural gas fuel system includes a fuel pod, a fuel regulator, and a shutoff valve. The fuel pod includes a plurality of natural gas fuel tanks positioned along the upper wall of the body assembly, and the fuel pod is coupled to the engine with a plurality of conduits that define a flow path. The fuel regulator is disposed along the flow path and configured to regulate a flow of natural gas to the engine. The shutoff valve is disposed along the flow path between the fuel pod and the fuel regulator, and the shutoff valve is coupled to a lower portion of the body assembly such that an operator standing alongside the vehicle may isolate the fuel pod by engaging the shutoff valve.
The invention is capable of other embodiments and of being carried out in various ways. Alternative exemplary embodiments relate to other features and combinations of features as may be recited in the claims.
The disclosure will become more fully understood from the following detailed description, taken in conjunction with the accompanying figures, wherein like reference numerals refer to like elements, in which:
Before turning to the figures, which illustrate the exemplary embodiments in detail, it should be understood that the present application is not limited to the details or methodology set forth in the description or illustrated in the figures. It should also be understood that the terminology is for the purpose of description only and should not be regarded as limiting.
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According to an exemplary embodiment, fuel control module 60 includes a pressure regulator configured to reduce the pressure of the natural gas from the tank pressure to a working pressure. In one embodiment, a heater (e.g., an electric heater) is coupled to the pressure regulator. The heater reduces the risk of freezing the valve due to the temperature decrease of the expanding natural gas. In one embodiment, the heater is controlled with a controller. The controller may operate according to a predetermined schedule (e.g., when the vehicle is running, a cycle of on for five minutes and off for five minutes, etc.) or may operate when a condition of the valve reaches a threshold value (e.g., when the valve temperature falls below 40 degrees Fahrenheit based on sensor signals from a temperature sensor, etc.). In still another embodiment, heat tape is wrapped around the pressure regulator, thereby reducing the risk of freezing the valve.
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High-pressure line 80, low-pressure line 90, and low-pressure line 100 define a flow path between fuel pod 40 and engine 30. In one embodiment, fuel flows from fuel pod 40 to engine 30, and accumulator 70 is positioned along the flow path downstream of fuel control module 60. In other embodiments, fuel pod 40 is coupled to a first end of a conduit that defines a flow path, the conduit having a second end that is configured to be coupled to an engine. Fuel control module 60 may be disposed along the flow path, and accumulator 70 may be disposed along the flow path downstream of fuel control module 60.
Fuel control module 60 may provide natural gas to low-pressure line 90 at a flow rate and pressure that varies based on a characteristic of the natural gas from fuel pod 40 (e.g., the pressure of the natural gas from fuel pod 40, the flow rate of natural gas from fuel pod 40, etc.). As natural gas in fuel pod 40 is depleted during use, the tank pressure and flow rate decreases. Various other factors may also contribute to variations in the inlet flow of natural gas (e.g., the natural gas in high-pressure line 80). Such variations in the inlet flow of natural gas may cause fluctuations in the stream of natural gas provided by fuel control module 60. By way of example, the fluctuations may include a pressure variation, a temperature variation, a flow rate variation, or still another variation. The fluctuations may be produced due to the physical interaction of the natural gas with a mechanical regulator of fuel control module 60 of for still another reason.
According to an exemplary embodiment, accumulator 70 is configured to buffer variations in the flow of natural gas such that engine 30 receives a consistent flow of natural gas (e.g., a flow of natural gas that varies within ten percent of a target flow rate, a flow of natural gas that varies within ten percent of a target pressure, etc.). By way of example, accumulator 70 may be configured to buffer pressure variations in the flow of natural gas such that engine 30 receives a flow of natural gas having a consistent pressure. By way of another example, accumulator 70 may be configured to buffer flow rate variations such that engine 30 receives natural gas at a consistent flow rate. During operation, pressure variations, flow rate variations, or still other variations may cause the power produced by engine 30 to fluctuate. Power fluctuations may be undesirable where, by way of example, engine 30 powers tractive elements of a refuse truck. In one embodiment, accumulator 70 includes a drain and is positioned at a low height relative to the other components of natural gas system 50. Such a position and drain allows for oil and other contaminants to be drained from natural gas system 50.
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Natural gas flows along a flow path through accumulator 70, according to an exemplary embodiment. The flow path may be defined between inlet 72 and outlet 74 through the inner volume of housing 76. A flow of natural gas entering inlet 72 may include one or more fluctuations. By way of example, the pressure, temperature, or flow rate, among other characteristics, of the flow entering inlet 72 may vary as a function of time. According to an exemplary embodiment, the inner volume of housing 76 contains a volume of natural gas that buffers fluctuations in pressure, temperature, or flow rate of natural gas flow through inlet 72. By way of example, a pressure fluctuation acting on natural gas at inlet 72 is dissipated as it propagates through the natural gas within the inner volume of housing 76 such that the pressure fluctuation is reduced or eliminated at outlet 74. According to another exemplary embodiment, an interaction between the flow of natural gas and an inner surface of housing 76 dissipates pressure variations as the natural gas flows between inlet 72 and outlet 74.
According to an exemplary embodiment, accumulator 70 buffers fluctuations in flow of natural gas through inlet 72 without buffering set point changes to pressure, temperature, flow rate, or other characteristics. By way of example, brief variations in the flow of natural gas may include variations in pressure or flow rate caused by a mechanical regulator whereas set point changes to pressure or flow rate may be provided according to a control strategy for the natural gas system.
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In one embodiment, the movable wall 110 is a rigid wall that may be actuated to change the inner volume of housing 76. According to the exemplary embodiment shown in
According to an exemplary embodiment, the inner volume of housing 76 is actively varied (e.g., by inflating and deflating the flexible bladder, by otherwise actuating movable wall 110, etc.) to counter pressure fluctuations in the flow of natural gas at inlet 72. By way of example, a pressure transducer may detect the pressure of the inlet flow of natural gas and provide sensor signals to a controller, and the controller may engage an actuator (e.g., a linear actuator, a rotational actuator, a source of a pressurized fluid, etc.) to generate a pressure wave that interfaces with and dampens the pressure fluctuation.
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In one embodiment, natural gas system 50 defines at least a portion of the fuel system for a vehicle. Fuel pod 40 may be positioned along the roof of a body assembly, according to an exemplary embodiment. In other embodiments, fuel pod 40 is positioned behind the drum on a concrete mixer truck. In still other embodiments, fuel pod 40 is still otherwise positioned. According to an exemplary embodiment, an operator may isolate each of the plurality of tanks 42 by closing shutoff valve 122. The position of shutoff valve 122 facilitates simultaneously stopping the flow of natural gas from each tank 42 of fuel pod 40. According to an exemplary embodiment, manifold 120 is positioned near fuel pod 40, thereby isolating a greater portion of the high-pressure natural gas system.
In the event of a fire onboard the vehicle, an operator may need to isolate each tank 42. Conventionally, where several natural gas tanks are positioned along the roof of a vehicle, an operator must climb to the roof of the vehicle and close valves to individually stop the flow of fuel from the tanks. Shutoff valve 122 facilitates the simultaneous disengagement of tanks 42, thereby reducing the need for an operator to shut off each tank 42 individually. In one embodiment, manifold 120 is positioned such that an operator standing alongside the vehicle may actuate shutoff valve 122, thereby reducing the need for the operator to board the vehicle to stop the flow of natural gas from tanks 42.
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According to an exemplary embodiment, high-pressure coalescing filter 130 removes contaminants (e.g., oil, debris, etc.) from the flow of natural gas before it reaches engine 30. As shown in
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In one embodiment, signal 142 is provided to a user interface (e.g., a display, a warning light, etc.) to alert an operator that high-pressure coalescing filter requires service or repair. In other embodiments, signal 142 is provided to still another system or device (e.g., a remote system that monitors the performance of the vehicle, a control system configured to limit the performance of the vehicle by entering a “limp mode” to prevent damage once the pressure differential exceeds the threshold value, etc.). Sending a service signal, a signal that encodes data, or providing a signal to another system reduces the likelihood that damage will occur to various components of the vehicle (e.g., engine 30, fouling of sensors or plugs, etc.) due to operating natural gas system 50 with an ineffective or clogged high-pressure coalescing filter 130.
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According to an exemplary embodiment, valve 150 is coupled to a controller, shown as controller 170. In one embodiment, controller 170 is coupled to solenoid 154. Controller 170 may send and receive signals (e.g., electrical pulses) to or from solenoid 154. According to the embodiment shown in
In one embodiment, controller 170 receives or retrieves the target pressure for the regulated flow of natural gas. By way of example, an operator may provide a target pressure using a user interface. By way of another example, a remote operation system may provide the target pressure to controller 170. By way of still another example, the target pressure may be stored in a memory (i.e. the target pressure may be retrieved by controller 170). Controller 170 may evaluate the target pressure and selectively engage valve 150.
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In one embodiment, controller 170 is configured to evaluate the sensor signals as part of a closed-loop control strategy. By way of example, controller 170 may be configured to evaluate the sensor signals from pressure transducer 180 and compare the pressure of the regulated flow of natural gas to the target pressure. Controller 170 may be configured to engage solenoid 154 while the pressure observed by pressure transducer 180 differs from the target pressure. Such a closed-loop control strategy may employ a deadband pressure variation (e.g., 5 PSI). Controller 170 is configured to not engage solenoid 154 when the pressure observed by pressure transducer 180 falls within the deadband pressure variation, according to one embodiment. Employing a deadband pressure variation reduces actuation of solenoid 154 and limits premature wear on the components of natural gas system 50, according to one embodiment. In other embodiments, controller 170 is configured to employ an open-loop control strategy and engage valve 150 without regard for the pressure of the regulated flow of natural gas.
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According to one embodiment, controller 170 is configured to determine the target pressure using information from at least one of engine 30 and sensor 182. In one embodiment, controller 170 is configured to determine the target pressure based on the requested throttle input. By way of example, the target pressure may increase such that engine 30 receives more fuel when an operator depresses a throttle pedal. In another embodiment, controller 170 is configured to determine the target pressure based on an engine condition (e.g., a current fuel consumption demand, etc.). In still another embodiment, controller 170 determines the target pressure using an offset provided by an operator. By way of example, an operator may manually control the target pressure or may engage a “high idle” mode and increase the target pressure above that required based the current engine conditions.
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Fuel pod 210 includes a plurality of natural gas fuel tanks, according to an exemplary embodiment, positioned along upper wall 234 of body assembly 230. Fuel pod 210 is coupled to engine 220 with a plurality of conduits that define a flow path. According to an exemplary embodiment, a fuel regulator 270 is disposed along the flow path and configured to regulate a flow of natural gas from fuel pod 210.
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According an exemplary embodiment, manifold 280 includes a shutoff valve 282 and a pressure transducer 284. As shown in
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At least one of the various controllers described herein may be implemented as a general-purpose processor, an application specific integrated circuit (ASIC), one or more field programmable gate arrays (FPGAs), a digital-signal-processor (DSP), a group of processing components, or other suitable electronic processing components. In one embodiment, at least one of the controllers includes memory and a processor. The memory is one or more devices (e.g., RAM, ROM, Flash Memory, hard disk storage, etc.) for storing data and/or computer code for facilitating the various processes described herein. The memory may be or include non-transient volatile memory or non-volatile memory. The memory may include database components, object code components, script components, or any type of information structure for supporting the various activities and information structures described herein. The memory may be communicably connected to the processor and provide computer code or instructions to the processor for executing the processes described herein. The processor may be implemented as a general-purpose processor, an application specific integrated circuit (ASIC), one or more field programmable gate arrays (FPGAs), a digital-signal-processor (DSP), a group of processing components, or other suitable electronic processing components.
It is important to note that the construction and arrangement of the elements of the systems and methods as shown in the embodiments are illustrative only. Although only a few embodiments of the present disclosure have been described in detail, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited. For example, elements shown as integrally formed may be constructed of multiple parts or elements. It should be noted that the elements and/or assemblies of the enclosure may be constructed from any of a wide variety of materials that provide sufficient strength or durability, in any of a wide variety of colors, textures, and combinations. The order or sequence of any process or method steps may be varied or re-sequenced, according to alternative embodiments. Other substitutions, modifications, changes, and omissions may be made in the design, operating conditions, and arrangement of the preferred and other embodiments without departing from scope of the present disclosure or from the spirit of the appended claims.
The present disclosure contemplates methods, systems, and program products on any machine-readable media for accomplishing various operations. The embodiments of the present disclosure may be implemented using existing computer processors, or by a special purpose computer processor for an appropriate system, incorporated for this or another purpose, or by a hardwired system. Embodiments within the scope of the present disclosure include program products comprising machine-readable media for carrying or having machine-executable instructions or data structures stored thereon. Such machine-readable media can be any available media that can be accessed by a general purpose or special purpose computer or other machine with a processor. By way of example, such machine-readable media can comprise RAM, ROM, EPROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code in the form of machine-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer or other machine with a processor. When information is transferred or provided over a network or another communications connection (either hardwired, wireless, or a combination of hardwired or wireless) to a machine, the machine properly views the connection as a machine-readable medium. Thus, any such connection is properly termed a machine-readable medium. Combinations of the above are also included within the scope of machine-readable media. Machine-executable instructions include, for example, instructions and data, which cause a general-purpose computer, special purpose computer, or special purpose processing machines to perform a certain function or group of functions.
Although the figures may show a specific order of method steps, the order of the steps may differ from what is depicted. Also two or more steps may be performed concurrently or with partial concurrence. Such variation will depend on the software and hardware systems chosen and on designer choice. All such variations are within the scope of the disclosure. Likewise, software implementations could be accomplished with standard programming techniques with rule-based logic and other logic to accomplish the various connection steps, processing steps, comparison steps, and decision steps.
Claims
1. A natural gas system for a vehicle, comprising:
- a fuel pod including a fuel tank configured to store natural gas;
- a conduit defining a flow path, the conduit including a first end coupled to the fuel pod and a second end configured to be coupled to an engine;
- a fuel control module disposed along the flow path and configured to regulate a flow of natural gas to the engine; and
- an accumulator disposed along the flow path downstream of the fuel control module, wherein the accumulator is configured to buffer variations in the flow of natural gas such that the engine receives a consistent flow of natural gas.
2. The system of claim 1, wherein the accumulator includes at least one of a supplementary length of conduit and a reservoir.
3. The system of claim 1, wherein the fuel pod comprises a plurality of fuel tanks.
4. The system of claim 3, further comprising a shutoff valve disposed along the flow path between the fuel pod and the fuel control module such that an operator may isolate the plurality of fuel tanks by closing the shutoff valve.
5. The system of claim 1, further comprising a filter disposed along the flow path downstream of the fuel control module.
6. The system of claim 5, further comprising a first pressure transducer positioned upstream of the filter and a second pressure transducer positioned downstream of the filter, wherein the first pressure transducer is configured to provide sensor signals relating to an upstream pressure of the natural gas and the second pressure transducer is configured to provide sensor signals relating to a downstream pressure of the natural gas.
7. The system of claim 6, further comprising a controller configured to evaluate the sensor signals from the first pressure transducer and the second pressure transducer to determine a pressure differential across the filter.
8. The system of claim 7, wherein the controller is configured to provide a service signal when the pressure differential across the filter exceeds a threshold value.
9. A vehicle, comprising:
- an engine;
- a tank configured to provide a supply flow of natural gas;
- a first conduit including a first end coupled to the tank;
- a valve coupled to a second end of the first conduit, wherein the first conduit comprises a high pressure flow path that extends continuously and directly from the tank to the valve, and wherein the valve is configured to provide a regulated flow of natural gas to the engine by adjusting the supply flow of natural gas;
- a second conduit defining a low pressure flow path, the second conduit including a first end coupled to the valve and a second end configured to be coupled to the engine;
- a pressure transducer disposed along the second conduit, wherein the pressure transducer is configured to provide sensor signals relating to a pressure of the regulated flow of natural gas;
- a sensor configured to provide information relating to a requested throttle input associated with the engine; and
- a controller configured to: monitor the sensor signals for a fluctuation in the regulated flow of natural gas; evaluate a target pressure for the regulated flow of natural gas based on the fluctuation and the information from the sensor; and selectively engage the valve such that the engine receives natural gas at the target pressure.
10. The vehicle of claim 9, wherein the controller is configured to evaluate the sensor signals and compare the pressure of the regulated flow of natural gas to the target pressure.
11. The vehicle of claim 9, wherein the valve includes a solenoid positioned to engage a movable valve element, wherein the pressure of the regulated flow of natural gas varies based on the position of the movable valve element.
12. The vehicle of claim 11, wherein the valve comprises a spool valve, and wherein the movable valve element comprises a spool.
13. The vehicle of claim 9, wherein the controller is configured to determine the target pressure based on an engine condition.
14. The vehicle of claim 9, wherein the fluctuation comprises a pressure variation from physical interaction of the natural gas with the valve.
15. A vehicle, comprising:
- a chassis including an engine coupled to a frame;
- a body assembly coupled to the frame, wherein the body assembly includes a plurality of sidewalls and an upper wall; and
- a natural gas fuel system, comprising: a fuel pod including a plurality of natural gas fuel tanks positioned along the upper wall of the body assembly, wherein the fuel pod is coupled to the engine with a conduit that defines a flow path; a fuel regulator disposed along the flow path and configured to regulate a flow of natural gas to the engine; and a shutoff valve disposed along the flow path between the fuel pod and the fuel regulator,
- wherein the shutoff valve is coupled to a lower portion of the body assembly such that an operator standing alongside the vehicle may isolate the fuel pod by engaging the shutoff valve.
16. The vehicle of claim 15, wherein the body assembly includes a fender panel, wherein the shutoff valve is positioned underneath the fender panel, and wherein the shutoff valve includes an actuation lever that protrudes through the fender panel.
17. The vehicle of claim 15, wherein the fuel pod includes a tank wrap positioned around at least one of the plurality of natural gas fuel tanks.
18. The vehicle of claim 15, further comprising a user access panel disposed along the flow path and coupled to the body assembly, wherein the user access panel is spaced from the fuel regulator.
19. The vehicle of claim 18, wherein the user access panel includes a high-pressure fuel gauge, a fuel receptacle, and a manual shutoff valve.
20. The vehicle of claim 19, wherein the fuel regulator is coupled to the frame and spaced from the plurality of sidewalls.
Type: Application
Filed: Jun 29, 2017
Publication Date: Oct 19, 2017
Applicant: Oshkosh Corporation (Oshkosh, WI)
Inventors: Grant D. Wildgrube (Fairbault, MN), Clint D. Glunz (Rochester, MN), Shashank Bhatia (Rochester, MN), Bryan S. Datema (Rochester, MN)
Application Number: 15/638,149