Cooling System With Dual Reversing Fans

Abstract

A cooling system comprises a first cooling package, a second cooling package, and a fan control system. The first cooling package comprises a first fan and at least one heat exchanger to cool at least one fluid associated with the machine. The first fan is configured to rotate in a cooling direction and an opposite cleaning direction. The second cooling package comprises a second fan and at least one heat exchanger to cool at least one fluid associated with the machine. The second fan is configured to rotate in a cooling direction and an opposite cleaning direction. The fan control system is configured to alternate the first and second fans between a first cleaning mode and a second cleaning mode.

Description

FIELD OF THE DISCLOSURE

The present disclosure relates to a cooling system for cooling one or more fluids of a machine.

BACKGROUND OF THE DISCLOSURE

Exhaust emissions standards are becoming more stringent. Such standards have placed an increased heat-rejection demand on cooling systems of off-highway equipment.

Vehicles use a cooling system to cool the engine, retarder, transmission, brakes, and air-conditioner condenser. The coolers of the cooling system get dirty over a period of use and, in at least some cases, receive manual cleaning by blowing them with an air gun. This maintenance process takes time and gets more difficult to perform if the dirt is left to accrue. It also adds to the time that the vehicle is unproductive. If left unattended, the vehicle will start to overheat and lose performance and eventually could fail one of the major components.

SUMMARY OF THE DISCLOSURE

According to the present disclosure, a cooling system comprises a first cooling package, a second cooling package, and a fan control system. The first cooling package comprises a first fan and at least one heat exchanger to cool at least one fluid associated with the machine. The first fan is configured to rotate in a cooling direction and an opposite cleaning direction. The second cooling package comprises a second fan and at least one heat exchanger to cool at least one fluid associated with the machine. The second fan is configured to rotate in a cooling direction and an opposite cleaning direction. The fan control system is configured to alternate the first and second fans between a first cleaning mode and a second cleaning mode.

In the first cleaning mode, the first and second fans concurrently rotate respectively in their cleaning and cooling directions advancing air in a first flow direction from the first fan to the second fan past the at least one heat exchanger of each of the first and second cooling packages. In the second cleaning mode the first and second fans concurrently rotate respectively in their cooling and cleaning directions advancing air in a second flow direction opposite the first flow direction from the second fan to the first fan past the at least one heat exchanger of each of the first and second cooling packages.

In an embodiment, the fan control system is configured to alternate successively the first and second fans between the first cleaning mode and the second cleaning mode during an exchanger-cleaning event. Successive alternation between the first and second cleaning modes promotes cleaning of the heat exchangers of foreign material (dirt, debris, etc.).

In another embodiment, during an exchanger-cleaning event, the fan control system is configured to operate the first and second fans sequentially in the first cleaning mode, an interim cleaning mode, and the second cleaning mode. In the interim cleaning mode, the first and second fans concurrently rotate respectively in their cleaning directions, promoting removal of debris from the compartment in which the heat exchangers are positioned.

In yet another embodiment, the fan control system is configured to alternate successive exchanger-cleaning events between the first cleaning mode and the second cleaning mode, with an exchanger-cooling event in a cooling mode therebetween. Such operation promotes fuel efficiency.

The above and other features will become apparent from the following description and the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description of the drawing refers to the accompanying figures in which:

FIG. 1 is a simplified top view showing advancement of air by a pair of fans during a cooling mode in which the fans operate in their cooling or forward directions;

FIG. 2 is a simplified top view showing advancement of air during a first cleaning mode in which the first fan (e.g., left side of drawing) operates in its cleaning or reverse direction as the “reverse fan” and the second fan (e.g., right side of drawing) operates in its cooling or forward direction as the “forward fan”;

FIG. 3 is a simplified top view showing advancement of air during a second cleaning mode in which the first fan operates in its cooling or forward direction as the forward fan and the second fan operates in its cleaning or reverse direction as the reverse fan;

FIG. 4 is a simplified top view showing advancement of air during an interim mode in which each of the first and second fans operates in its cleaning or reverse direction as a reverse fan;

FIG. 5 is a simplified schematic view of a fan control system;

FIG. 6 is a first control routine that cycles the fans between the first and second cleaning modes during an exchanger-cleaning event;

FIG. 7 is an alternative embodiment of the first control routine adding an interim step in which both fans are reversed simultaneously between the first and second cleaning modes to promote debris removal;

FIG. 8 is a second control routine in which successive exchanger-cleaning events alternate between the first and second cleaning modes, with an exchanger-cooling event in a cooling mode therebetween; and

FIG. 9 is a chart showing sequential reversal of the fans in an exchanger-cleaning event.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to FIG. 1, there is shown a machine 10 which may take the form of, for example, an articulated dump truck or other work vehicle having a fore-aft axis 11. Exemplarily, as an articulated dump truck, the machine 10 has a front section 12 and a rear section, the front and rear sections being articulated to one another and positioned along the fore-aft axis 11. The front section 12 has the operator's station and an engine compartment 18 in front of the operator's station. The rear section has a tippable dump body configured to carry a payload.

The machine 10 has a cooling system 22 for cooling a number of fluids of the machine 10. The cooling system 22 has a first cooling package 24, a second cooling package 26, and a fan control system 28.

The first cooling package 24 has a first fan 30 and at least one heat exchanger 32 to cool at least one fluid associated with the machine 10. The first fan 30 is configured to rotate in a cooling or forward direction 34-1 and an opposite cleaning or reverse direction 34-2.

The second cooling package 26 has a second fan 36 and at least one heat exchanger 38 to cool at least one fluid associated with the machine 10. The second fan 36 is configured to rotate in a cooling or forward direction 40-1 and an opposite cleaning or reverse direction 40-2.

The fan control system 28 is configured to operate the first and second fans 30, 36 in a cooling mode to cool one or more fluids of the machine 10 during an exchanger-cooling event and in one or more cleaning modes to clean the at least one heat exchanger 32, 38 of each of the first and second cooling packages 24, 26 during an exchanger-cleaning event. Referring to FIG. 1, in the cooling mode, the first and second fans 30, 36 concurrently rotate respectively in their cooling directions 34-1, 40-1 advancing air from a common air inlet respectively past the first and second cooling packages 24, 26 to the first and second fans 30, 36 and out respective air outlets.

The fan control system 28 is configured to alternate successively the first and second fans 30, 36 between a first cleaning mode and a second cleaning mode during an exchanger-cleaning event. Referring to FIG. 2, in the first cleaning mode the first and second fans 30, 36 concurrently rotate respectively in their cleaning and cooling directions 34-2, 40-1 advancing air in a first flow direction 42 from the first fan 30 to the second fan 36 past the at least one heat exchanger 32, 38 of each of the first and second cooling packages 24, 26. Referring to FIG. 3, in the second cleaning mode the first and second fans 30, 36 concurrently rotate respectively in their cooling and cleaning directions 34-1, 40-2 advancing air in a second flow direction 44 opposite the first flow direction 42 from the second fan 36 to the first fan 30 past the at least one heat exchanger 32, 38 of each of the first and second cooling packages 24, 26.

The fan control system 28 is configured to cycle the first and second fans 30, 36 between the first and second cleaning modes for one or more cycles during the exchanger-cleaning event. For example, the fan control system 28 is configured to cycle the fans 30, 36 between the first and second cleaning modes for one cycle during the exchanger-cleaning event.

Exemplarily, the first and second cooling packages 24, 26 are positioned on laterally opposite sides of a fore-aft axis 11 of the machine 10 such that the first and second flow directions 42, 44 are laterally opposite to one another. The first cooling package 24 may be positioned on the right-hand side of the axis 11, and the second cooling package 26 may be positioned on the left-hand side of the axis 11. The at least one heat exchanger 32 of the first cooling package 24 and the at least one heat exchanger 38 of the second cooling package 26 are positioned laterally between the first and second fans 30, 36. Exemplarily, an internal combustion engine 48 (e.g., diesel engine) is positioned laterally between the first and second cooling packages 24, 26.

Each of the first and second cooling packages 24, 26 may have a number of heat exchangers. Exemplarily, the first cooling package 24 has three units of one or more heat exchangers 32 stacked laterally relative to one another, with a laterally outward unit, a laterally inward unit, and a laterally intermediate unit positioned laterally between the laterally outward and inward units. The laterally outward unit is positioned laterally between the first fan 30 and the laterally intermediate unit. The laterally inward unit is positioned laterally between the laterally intermediate unit and the engine 48. The laterally outward unit is a radiator 32-1 configured to cool engine coolant. The laterally intermediate unit is a combination cooler having, from rear to front, a transmission-and-retarder oil cooler 32-2 configured to cool oil of the transmission and retarder and a hydraulic oil cooler 32-3 configured to cool hydraulic oil. The transmission-and-retarder oil cooler and the hydraulic oil cooler are adjacent to one another and are fastened to another (e.g., using bolts and nuts). The laterally inward unit is a fuel cooler 32-4 configured to cool fuel. The first cooling package 24 may be configured in any suitable fashion (e.g., the number, size, use, layout, etc. of heat exchangers may be different for a given machine).

Exemplarily, the second cooling package 26 has two units of one or more heat exchangers 38 stacked laterally relative to one another, with a laterally outward unit, a laterally inward unit, and a laterally intermediate unit positioned laterally between the laterally outward and inward units. The laterally outward unit is positioned laterally between the second fan 36 and the laterally intermediate unit. The laterally inward unit is positioned laterally between the laterally outward unit and the engine 48. The laterally outward unit is a radiator 38-1 configured to cool engine coolant. The laterally intermediate unit is a combination cooler having, from rear to front, a first brake cooler 38-2 configured to cool an axle and associated brakes (e.g., the middle axle of an articulated dump truck, a second brake cooler 38-3 configured to cool an axle and associated brakes (e.g., the front axle of an articulated dump truck), and a charge-air cooler 38-4 configured to cool pressurized engine intake air. The second brake cooler is positioned between the first brake cooler and the air conditioner condenser and is fastened to them (e.g., using bolts and nuts). The laterally inward unit is an air-conditioning condenser 38-5. The second cooling package 26 may be configured in any suitable fashion (e.g., the number, size, use, layout, etc. of heat exchangers may be different for a given machine).

Exemplarily, the two radiators 32-1, 38-1 of the first and second cooling packages 24, 26 are flow-parallel to one another. In such a case, a first node is coupled fluidly to a coolant outlet of the engine 48 and respective coolant inlets of the two radiators, and a second node is coupled fluidly to respective coolant outlets of the two radiators and a coolant inlet of the engine 48.

Referring to FIG. 5, the fan control system 28 may be configured in any suitable manner to control operation of the fans 30, 36. Exemplarily, the fan control system 28 has a first electro-hydraulic system 68 for the first fan 30 and a second electro-hydraulic system 69 for the second fan 36, the systems 68, 69 sharing a hydraulic fluid reservoir tank. Each electro-hydraulic system 68, 69 has a variable displacement hydraulic pump 70 and a hydraulic motor 72. The motor 72 is coupled mechanically to the respective fan 30, 36 to drive that fan in either direction. The pump 70 is coupled hydraulically to the respective motor 72 to drive that motor 72, and may be, for example, an axial-piston pump. The first electro-hydraulic system 68 has a displacement control mechanism that provides pressure-compensated, load-sense (LS) control of the pump 70 (e.g., of the swash plate of the pump 70). The displacement of the pump 70 of the second electro-hydraulic system 69 is electronically controlled using a displacement control mechanism discussed below. The controller 58 is coupled electrically to a speed sensor (e.g., Hall-effect sensor with 12 pulses per revolution) in each motor 72 to receive information indicative of the rotational speed of the respective fan 30, 36 in order to control such speed.

Each electro-hydraulic system 68, 69 has a directional control valve 74, a reverse valve 76, and a speed valve 78. The directional control valve 74 is configured to direct hydraulic fluid selectively to either of two work ports of the motor 72 to control the direction of rotation of the motor 72. The reverse valve 76 is configured as an on/off valve and is coupled electrically to an electric first controller 58 of the machine 10 (e.g., chassis control unit) so as to be under the control of the controller 58. The reverse valve 76 is coupled hydraulically to the pump 70 and a pilot port of the directional control valve 74 to direct supply pressure to the pilot port of the directional control valve 74 when the solenoid of the reverse valve 76 is energized by the controller 58. Energizing and de-energizing the reverse valve 74 causes the spool of the directional control valve 74 to shift accordingly to change the direction of flow to the motor 72 and thus the direction of rotation of the respective fan 30, 36.

An intermediate, transition section of the directional control valve 74 is configured to couple fluidly the two work ports of the motor 72 through the valve 74 momentarily allowing the respective fan 30, 36 to freewheel during shifting of the spool between a first position directing hydraulic fluid to a first work port of the motor 72 and a second position directing hydraulic fluid to a second work port of the motor 72. Such a work port connection promotes motor life by avoiding a sudden deadhead of the motor 72 that might otherwise occur in the absence of the transition section.

Each electro-hydraulic system 68, 69 has a first pressure-relief valve 77 and a second pressure-relief valve 79. The first pressure-relief valve 77 is coupled fluidly to the pressure supply line from the respective pump 52 and a return line to tank. The second pressure-relief valve 79 is coupled fluidly to either side of the first pressure-relief valve 77 in parallel thereto, and has a pressure-relief setting lower than that of the valve 77. The second pressure-relief valve 77 is coupled electrically to the first controller 58 so as to be under the control of that controller 58. When the controller 58 energizes the solenoid of the reverse valve 76, it energizes the solenoid of the second pressure-relief valve 79 momentarily so as to relieve pressure in the pressure supply line as the spool of the directional control valve 74 passes through its intermediate, transition section, avoiding transmission of a pressure spike to upstream components with respect to the first electro-hydraulic system 68 and to the pump 70 with respect to the second electro-hydraulic system 69.

The speed valve 78 of the first electro-hydraulic system 68 is configured, for example, as a proportional load-sense relief valve and is operable to vary the speed of rotation of the fan 30. The speed valve 78 is coupled electrically to the controller 58 so as to be under the control of the controller 58 (e.g., by pulse-width modulation or “PWM” such as, for example, PWM to ground with system voltage to high side of valve 78 in response to vehicle start-up). The controller 58 is configured to command the speed valve 78 to open by energizing its solenoid in order to bleed hydraulic fluid from an associated load sense line LS1 so as to slow the fan speed. De-energizing the solenoid of the speed valve 78 increases the fan speed.

The speed valve 78 of the second electro-hydraulic system 69 is configured, for example, as a proportional valve and is included in the displacement control mechanism for the pump 70 of the system 69. The displacement control mechanism has a hydraulic first cylinder 86 and a hydraulic second cylinder 88, both cylinders 86, 88 coupled to the displacement control of the pump 70 (e.g., swash plate). The speed valve 78 has two work ports coupled fluidly respectively to the first cylinder 86 and the second cylinder 88. The speed valve 78 is spring-biased to route hydraulic fluid from the supply line to the first cylinder 86 so as to displace the pump 70 fully for maximum speed of the second fan 36. The speed valve 78 is coupled electrically to the controller 58 so as to be under the control of the controller 58 (e.g., by pulse-width modulation or “PWM” such as, for example, PWM to ground with system voltage to high side of valve 78 in response to vehicle start-up). The controller 58 is configured to command the speed valve 78 to shift by energizing its solenoid in order to route hydraulic fluid from the supply line to the second cylinder 88 so as to slow the second fan 36. De-energizing the solenoid of the speed valve 78 increases the fan speed.

Each pump 70 can be a pump dedicated to the respective fan 30, 36, or it may be shared with other functions. Exemplarily, the pump 70 of the second electro-hydraulic system 69 is dedicated to the second fan 36, whereas the pump 70 of the first electro-hydraulic system 68 is shared with other functions (e.g., steering, brake, axle cooling, dump body tip, suspension) and, as such, may be the main hydraulic pump of the machine 10. In such a case, the pump 70 of the first electro-hydraulic system 68 may be driven off of the transmission, coupled to the engine 48, and the pump 70 of the second electro-hydraulic system 69 may be driven off the engine 48 (e.g., mounted directly to the engine 48) with a gear pump exemplarily stacked behind it.

For simplification, with respect to the first electro-hydraulic system 68, components between the “shared” pump 70 and the motor 72 associated with the fan 30 are shown, although the other functions are not shown. Such components include an attenuator 80, a priority valve 81, an electro-hydraulic cut-off valve 82, and a compensator valve 84. The attenuator 80 attenuates noise due, for example, to pressure pulsation from the pump 70 of the first electro-hydraulic system 68. The priority valve 81 establishes priority flow for steering (and also for brakes but mainly for steering). The cut-off valve 82 is closed during tipping of the dump body of the machine 10 to decrease the time that it takes to tip the dump body in response to a signal from the first controller 58 due to movement of the dump body (e.g., caused by displacement of the dump lever or actuation of a dump body-up button or a dump body-down button). The compensator valve 84 regulates the pressure supplied to the motor 72 to be that which is commanded of the speed valve 78 (e.g., if the load-sense system causes the pump 70 to output a pressure greater than what is needed for the fan 30, the compensator valve 84 will reduce that pressure to the pressure called for by the speed valve 78). The load-sense system for the “shared” pump 70 is identified as “LS1” in FIG. 5, and exemplarily includes a network of shuttle valves associated with various functions to establish the load-sense signal back to the pump control. A system pressure-relief unit 89 is positioned in the system 68 ahead of the function(s) of the system 68.

Referring to FIG. 6, there is shown a flowchart of a control routine 110 for cleaning the heat exchangers 32, 38 of the first and second cooling packages 24, 26 in the cleaning mode. The cleaning mode may be initiated automatically or manually by the operator. Automatic initiation occurs in step 112, and manual initiation occurs in step 114.

In step 112, the electric first controller 58 of the control system 28 (e.g., the chassis control unit) monitors elapsed time (t) since the end of the last cleaning event of the cooling packages 24, 26, and determines if a predetermined period of time (Δt) has elapsed since the end of that event. A timer 62 tracks such elapsed time, and is included in the controller 58, or may be a stand-alone device or part of another controller. The predetermined period of time may be selected by the operator through, for example, a display monitor at the operator's station (e.g., ½ hour, 1 hour, 2 hours, 3 hours, 4 hours), or it may be a default value (e.g., 4 hours). If the predetermined period of time has elapsed, the routine 110 advances to step 116. If no, the controller 58 continues to monitor elapsed time since the last exchanger-cleaning event.

In step 114, an operator or other person can manually request activation of the cleaning mode through a display monitor at the operator's station. If a manual request has been received, the routine 110 advances to step 116.

In step 116, the controller 58 determines whether any of a number of inhibit conditions is present. The conditions monitored may include, for example: the temperature of any of the fluids in the heat exchangers of the cooling packages 24, 26 is at or above its respective maximum allowable temperature (since a cleaning event will reduce cooling); the windshield wipers are off (since wiper activation is indicative of rain which could cause a cloud of dust discharged from the machine 10 during cleaning to stick to windows of the operator's station); and a diesel particulate filter is being regenerated (e.g., based on a CAN message received by the controller 58 from an electric second controller 60 such as an engine control unit). The controller 58 receives inputs indicative of whether any such inhibit condition exists. If the controller 58 determines that an inhibit condition exists, the controller 58 waits to activate the cleaning mode until such condition terminates. If a manual request for cleaning was received, the controller 58 may initiate activation of an alert (e.g., on the display monitor) indicating that the cleaning mode is inhibited. If no inhibit condition exists, the routine 110 advances to step 118.

Other inhibit conditions may include, for example, one or more of the following: engine speed is not greater than a threshold engine speed (e.g., 1400 rpm), since lower engine speeds may not provide sufficient hydraulic flow to reach maximum fan speed (in other words, engine speeds greater than 1400 rpm may provide sufficient hydraulic flow to reach maximum fan speed; it is thought that engine idle speed may even be sufficient); and ground speed of the machine 10 is greater than a threshold ground speed (e.g., 5 miles per hour), so as to reduce the likelihood that a person is in the path of discharge.

In step 118, the controller 58 activates an exchanger-cleaning event in which the controller 58 alternates successively the first and second fans 30, 36 between the first cleaning mode and the second cleaning mode. Such alternating succession may occur for one or more cycles (e.g., one cycle). During each cycle, the first cleaning mode is performed followed by performance of the second cleaning mode.

In step 118-1 of step 118, the controller 58 activates the first cleaning mode. In the first cleaning mode, the first and second fans 30, 36 concurrently rotate respectively in their cleaning and cooling directions 34-2, 40-1 advancing air in a first flow direction 42 laterally relative to the fore-aft axis 11 from the first fan 30 to the second fan 36 past the at least one heat exchanger 32, 38 of each of the first and second cooling packages 24, 26.

Referring to FIG. 9, to reverse the first fan 30 from its cooling direction to its cleaning direction, in time T1, the controller 58 commands operation of the speed valve 78 associated with the first fan 30 (gradually energizes its solenoid) (i.e., the first speed valve 78) to ramp down the speed of the first fan 30 at a predetermined rate (e.g., 100 rpm/second) toward a zero fan speed using the speed information from the speed sensor in the first fan motor 72. Such ramping down helps to avoid fan motor cavitation. When the fan speed reaches a predetermined fan idle speed (e.g., 600 rpm), the controller 58 commands operation of the first speed valve 78 so as to command the first fan 30 to the zero fan speed (i.e., commands maximum current to the valve 78 assuming no fault requiring abort), and begins to monitor the fan speed for up to a predetermined period of time (e.g., 10 seconds) using the speed information from the speed sensor in the first fan motor 72 (the controller 58 is unable to control the 100 rpm/second rate below the fan idle speed). The solenoid of the reverse valve 76 associated with the first fan 30 9 (i.e., the first reverse valve 76) is de-energized during time T1.

If, during the predetermined period of time, the fan speed reaches zero, time T2 starts immediately. If, at the end of the predetermined period of time, the fan speed does not reach zero but reaches below a low-speed threshold (e.g., 100 rpm), time T2 starts at the end of the predetermined period of time. If neither condition occurs, the controller 58 aborts reversal of the first fan 30, and begins reversal of the second fan 36 (i.e., advances the second fan 36 from T1-T7). As for the first fan 30, the controller 58 commands operation of the first speed valve 78 (gradually decreases its current) to ramp up the speed of the first fan 30 at a predetermined rate (e.g., 100 rpm/second) to a variable forward speed based on the cooling need of the first cooling package 24 using the speed information from the speed sensor in the first fan motor 72.

In time T2, the controller 58 commands operation of the first speed valve 78 so as to command the first fan 30 to the zero fan speed (i.e., commands maximum current to the valve 78 assuming no fault requiring abort), and monitors the fan speed of the first fan 30 for a predetermined period of time using the speed information from the speed sensor in the first fan motor 72 to confirm if the fan speed remains below the low-speed threshold. The predetermined period of time may be between a few milliseconds and a few seconds. It may be, for example, 10 milliseconds or, preferably, two seconds to ensure that the fan speed has indeed reduced to a desired level for changing its direction of rotation since the speed sensor does not indicate direction of rotation. If, during the predetermined period of time, the fan speed of the first fan 30 is equal to or greater than the low-speed threshold, the controller 58 aborts reversal of the first fan 30 and begins reversal of the second fan 36 (i.e., advances the second fan 36 from T1-T7), and, regarding the first fan 30, the controller 58 commands operation of the first speed valve 78 (gradually decreases its current) to ramp up the speed of the first fan 30 at a predetermined rate (e.g., 100 rpm/second) to a variable forward speed based on the cooling need of the first cooling package 24 using the speed information from the speed sensor in the first fan motor 72. The solenoid of the first reverse valve 76 is de-energized during time T2.

In time T3, the controller 58 energizes the solenoid of the first reverse valve 76 and commands operation of the first speed valve 78 (proportionally energizes its solenoid) so as to reverse the direction of hydraulic flow to the first fan motor 72 and command the speed of the first fan 30 to a predetermined reverse speed threshold (e.g., 1600 rpm). The controller 58 monitors the speed information from the speed sensor in the first fan motor 72 for up to a predetermined amount of time (e.g., two seconds) to confirm if a non-zero fan speed has been achieved, as there will be a natural initial system delay (due, for example, to solenoid saturation, valve hysteresis, and time to measure fan speed). If the non-zero fan speed has not been achieved within the predetermined period of time, the controller 58 aborts reversal of the first fan 30 and begins reversal of the second fan 36 (i.e., advances the second fan 36 from T1-T7). During abort of the first fan 30, the controller 58 de-energizes the solenoid of the first reverse valve 76 and commands operation of the first speed valve 78 (gradually decreases its current) to ramp up the speed of the first fan 30 at a predetermined rate (e.g., 100 rpm/second) to a variable forward speed based on the cooling need of the first cooling package 24 using the speed information from the speed sensor in the first fan motor 72.

Time T4 begins when the controller 58 determines that the first fan 30 has achieved a non-zero fan speed using the speed information from the speed sensor in the first fan motor 72. In time T4, the controller 58 continues to energize the solenoid of the first reverse valve 76 and to energize proportionally the solenoid of the first speed valve 78 so as to command the predetermined reverse speed threshold, and monitors the fan speed for up to a predetermined period of time (e.g., four seconds) to confirm if the predetermined reverse speed threshold has been achieved. If the predetermined reverse speed threshold has not been achieved in the predetermined period of time, the controller 58 aborts reversal of the first fan 30, and begins reversal of the second fan 36 (i.e., advances the second fan 36 from T1-T7).

To abort reversal of the first fan 30 in time T4, the controller 58 commands operation of the first speed valve 78 so as to command the first fan 30 to a zero fan speed (i.e., commands maximum current to the valve 78 assuming no fault requiring machine shutdown and restart so as to de-energize the valve 78 thereby resetting it in case the second speed valve 78 is malfunctioning) and monitors the fan speed for up to a predetermined period of time (e.g., 10 seconds) using the speed information from the speed sensor in the first fan motor 72. If, during the predetermined period of time, the fan speed reaches zero, or, at the end of the predetermined period of time, the fan speed is at least below the low-speed threshold, the controller 58 continues to command the zero fan speed for another predetermined period of time (e.g., two seconds), in response to elapse of which the controller 58 de-energizes the solenoid of the first reverse valve 76 and commands operation of the first speed valve 78 (gradually decreases its current) to ramp up the speed of the first fan 30 at a predetermined rate (e.g., 100 rpm/second) to a variable forward speed based on the cooling need of the first cooling package 24 using the speed information from the speed sensor in the first fan motor 72. The controller 58 begins reversal of the second fan 36 when the speed of the first fan 30 drops below the low-speed threshold (i.e., advances the second fan 36 from T1-T7).

When the predetermined reverse speed threshold is reached, time T5 begins, in which the controller 58 continues to energize the solenoid of the first reverse valve 76 and to energize the solenoid of the first speed valve 78 so as to command the speed of the first fan 30 to be the reverse speed threshold for a predetermined period of reverse time. That predetermined period of time may be, for example, 30 seconds, or, in the case of worksites with excessive debris, 60 seconds. Such period of time may be selectable by the operator via a display monitor in the operator's station. Once the fan speed reaches the reverse speed threshold, the controller 58 starts counting the amount of reverse time in which the first fan 30 is at or above the reverse speed threshold. If the fan speed drops below the threshold, the controller 58 stops counting the reverse time. Instead, the controller 58 starts counting the amount of time below the threshold. As such, when the fan speed is at or above the threshold, time is accrued toward the predetermined period of reverse time, whereas, when the fan speed is below the threshold, time is accrued toward a predetermined period of fault time which may be, for example, 30 seconds. The reverse time and the fault time are thus both cumulative. If the reverse time is reached before the fault time is reached, the controller 58 proceeds to time T6. If the fault time is reached before the reverse time is reached, the controller 58 aborts reversal of the first fan 30, and begins reversal of the second fan 36. The abort sequence in time T5 is the same as the abort sequence in T4.

In time T6, the controller 58 commands operation of the first speed valve 78 to command the speed of the first fan 30 to zero (i.e., commands maximum current to the valve 78 assuming no fault requiring abort), at an uncontrolled rate. Since this speed decrease is uncontrolled (the first fan 30 freewheels), the controller 58 monitors the fan speed for up to a predetermined period of time (e.g., 10 seconds) using the speed information from the speed sensor in the first fan motor 72. If, during the predetermined period of time, the fan speed reaches zero, time T7 starts immediately. If, at the end of the predetermined period of time, the fan speed does not reach zero but reaches below the low-speed threshold (e.g., 100 rpm), time T7 starts at the end of the predetermined period of time. If neither condition occurs, the controller 58 aborts the exchanger-cleaning event altogether in order to avoid reversing both fans 30, 36 at the same time, and may therefore require the machine 10 to be shut down and re-started (e.g., so as to de-energize the second speed valve 78 thereby resetting it in case the second speed valve 78 is malfunctioning).

In time T7, the controller 58 commands operation of the first speed valve 78 so as to command the first fan 30 to the zero fan speed (i.e., commands maximum current to the valve 78 assuming no fault requiring abort), and monitors the fan speed of the first fan 30 for a predetermined period of time using the speed information from the speed sensor in the first fan motor 72 to confirm if the fan speed remains below the low-speed threshold. The predetermined amount of time may be between a few milliseconds and a few seconds. It may be, for example, 10 milliseconds or, preferably, two seconds to ensure that the fan speed has indeed reduced to a desired level for changing its direction of rotation since the speed sensor does not indicate direction of rotation. If the fan speed remains below the low-speed threshold for the predetermined period of time, at the end of T7, the controller 58 de-energizes the solenoid of the first reverse valve 76 and commands operation of the first speed valve 78 (gradually decreases its current) to ramp up the speed of the first fan 30 at a predetermined rate (e.g., 100 rpm/second) to a variable forward speed based on the cooling need of the first cooling package 24 using the speed information from the speed sensor in the first fan motor 72. If the fan speed does not remain below the low-speed threshold, the controller 58 aborts the exchanger-cleaning event altogether in order to avoid reversing both fans 30, 36 at the same time, and may therefore require the machine 10 to be shut down and re-started (e.g., so as to de-energize the second speed valve 78 thereby resetting it in case the second speed valve 78 is malfunctioning).

The routine 110 advances to step 118-2 of step 118 as soon as the zero fan speed of the first fan 30 has been achieved in T6 or if the fan speed of the first fan 30 is below the low-speed threshold at the end of the predetermined period of time of T6. In step 118-2, the controller 58 activates the second cleaning mode, while concluding the first cleaning mode by advancing the first fan 30 through T7 and ramping its fan speed to a forward speed.

In the second cleaning mode, the first and second fans 30, 36 concurrently rotate respectively in their cooling and cleaning directions 34-1, 40-2 advancing air in a second flow direction 44 opposite the first flow direction 42 laterally relative to the fore-aft axis 11 from the second fan 36 to the first fan 30 past the at least one heat exchanger 32, 38 of each of the first and second cooling packages 24, 26. To do so, the controller 58 reverses the second fan 36 according to the reversal sequence (i.e., T1-T7) described above for the first fan 30 in the first cleaning mode 118-1 and aborts in the same manner if necessary, except that, in the event of an abort of reversal of the second fan 36 in any of T1-T5, the controller 58 aborts the exchanger-cleaning event altogether (i.e., does not reverse the first fan 30 since the first fan 30 would have already been reversed). With respect to the second cleaning mode, the speed valve 78 associated with the second fan 36 (second speed valve 78) and the reverse valve 76 associated with the second fan 36 (second reverse valve 76) are involved. In the event of an abort during T6 or T7, the controller 58 aborts the exchanger-cleaning event altogether, and may therefore require the machine 10 to be shut down and re-started (e.g., so as to de-energize the second speed valve 78 thereby resetting it in case the second speed valve 78 is malfunctioning).

When finished with the reversal sequence for the second fan 36 (i.e., T1-T7), the control routine 110 advances to step 120 so as to resume the cooling mode. In step 120, if the fan speed remains below the low-speed threshold for the predetermined period of time, at the end of T7, the controller 58 de-energizes the second reverse valve 76 and commands operation of the second speed valve 78 (gradually decreases its current) to ramp up the speed of the second fan 36 at a predetermined rate (e.g., 100 rpm/second) to a variable forward speed based on the cooling need of the second cooling package 26 using the speed information from the speed sensor in the second fan motor 72. As alluded to above, if the fan speed does not remain below the low-speed threshold, the controller 58 aborts the exchanger-cleaning event altogether, and may therefore require the machine 10 to be shut down and re-started (e.g., so as to de-energize the second speed valve 78 thereby resetting it in case the second speed valve 78 is malfunctioning).

During reversal of the first fan 30, the controller 58 commands operation of the second fan 36 at a forward speed based on the cooling need of the cooling package 26 through de-energization of the second reverse valve 76 and proportional control of the second speed valve 78. An electric second controller 60 (e.g., engine control unit coupled electrically to the first controller 58 via a controller area network, i.e., CAN) determines the fan speed of the second fan 36 based on the cooling need of the fluid of the second cooling package 26 closest to its upper temperature limit (alternatively, the electric first controller 58 could perform this function). Exemplarily, the second controller 60 receives the engine coolant temperature from a temperature sensor, and sends this value to the first controller 58 for determination of whether an inhibit condition exists. The second controller 60 sends that fan speed to the electric first controller 58 which controls the second speed valve 78 so as to operate the second fan 36 at that fan speed. The first fan 30 is operated in a corresponding manner during reversal of the second fan 36.

Referring to FIGS. 4 and 7, an alternative embodiment of the step 118 is shown as step 218, and includes an interim step 218-3 due to overlap of activation of the first and second cleaning modes in steps 218-1 and 218-2, respectively. In step 218-3, the controller 58 commands operation of the fans 30, 36 such that the fans 30, 36 concurrently rotate respectively in their cleaning directions for an interim predetermined period of time so as to blow air inwardly toward the engine 48 to cause debris to blow out any openings in the compartment 18 (e.g., any openings between panels, and front grill).

To do so, in step 218-2, the controller 58 activates the first cleaning mode, advancing the first fan 30 in sequence from T1 to T5, while the second fan 36 continues to operate at a variable fan cooling speed. While the first fan 30 is still in T5 or immediately afterwards during which the controller 58 keeps the first fan 30 at the predetermined reverse speed threshold (e.g., 1600 rpm), the controller 58 activates the second cleaning mode reversing the second fan 36 from its cooling direction to its cleaning direction by advancing it in sequence through T1, T2, T3, and T4 to the predetermined reverse speed threshold. The controller 58 keeps the fan speed of the fans 30, 36 at the predetermined reverse speed threshold for an interim predetermined period of time (e.g., 10 seconds). Upon elapse of the interim predetermined period of time, the controller 58 concludes the first cleaning mode, advancing the first fan 30 in sequence through T6 and T7, after which it commands the first fan 30 to a variable forward speed (assuming no abort). It subsequently concludes the second cleaning mode, advancing the second fan 36 in sequence through T5, T6, and T7, after which it commands the second fan 36 to a variable forward speed (assuming no abort).

Thus, the controller 58 may be configured to operate the first and second fans 30, 36 sequentially in the first cleaning mode, the interim cleaning mode, and the second cleaning mode during an exchanger-cleaning event, with the first and second cleaning modes overlapping to provide the interim cleaning mode.

Referring to FIG. 8, a control routine 310 provides an alternative embodiment to control routine 110. The control routine 310 alternates between the cooling mode and a cleaning mode, and the cleaning mode may be activated in any suitable manner such as by elapse of a predetermined period of time (e.g., step 112) or by manual request (e.g., step 114), assuming one of the inhibit conditions is not present (e.g., step 116). In other words, the routine 310 will perform steps 112, 114, and 116 before performing a cleaning mode.

The control routine 310 is different in that each exchanger-cleaning event involves only one of the first and second cleaning modes such that successive exchanger-cleaning events alternate between the first and second cleaning modes. For example, the control routine 310 may advance from the cooling mode in step 316 to only the first cleaning mode in step 318 (does not include the second cleaning mode during this exchanger-cleaning event). The routine 310 may then advance back to the cooling mode in step 320 and then to only the second cleaning mode in step 322 (does not include the first cleaning mode during this exchanger-cleaning event). This pattern may continue, promoting fuel economy since both cleaning modes are not activated during an exchanger-cleaning event.

In step 318, the controller 58 operates the first and second fans 30, 36 in their cleaning and cooling directions, respectively, in a manner similar to what is discussed in connection with step 118-1 of FIG. 6. In step 320, the controller 58 returns the first fan 30 to its cooling direction to a variable forward speed based on cooling need. In step 322, the controller 58 operates the first and second fans 30, 36 in their cooling and cleaning directions, respectively, in a manner similar to what is discussed in connection with step 118-2 of FIG. 6. The routine 310 then advances back to step 316, in which the controller 58 returns the second fan 36 to its cooling direction to a variable forward speed based on cooling need. The controller 58 may thus be configured to alternate successive exchanger-cleaning events between the first cleaning mode and the second cleaning mode. In the event an abort of the reversal sequence of either fan 30, 36 is triggered in any of T1-T7, the controller 58 performs the abort sequence associated with the respective time period (discussed above in connection with routine 110 and fan 30) without reversing the other fan, thereby aborting the exchanger-cleaning event altogether.

In the control routine 110, it is thought that, during each of the first and second cleaning modes, about 86 percent of the debris in the engine compartment 18 is removed from the engine compartment while about 10 percent remains.

In the control routines discussed herein, during a cleaning mode, the forward fan (i.e., the fan operating in its forward direction) is operated at a variable forward speed based on cooling needs. Alternatively, the controller 58 may operate the forward fan at its maximum calibrated operating speed.

Cooling is more efficient in the cooling mode than any of the cleaning modes, but also takes place during the exchanger-cleaning event.

The cooling system 22 may be used with an articulated machine (e.g., machine 10) or a non-articulated machine.

While the disclosure has been illustrated and described in detail in the drawings and foregoing description, such illustration and description is to be considered as exemplary and not restrictive in character, it being understood that illustrative embodiment(s) have been shown and described and that all changes and modifications that come within the spirit of the disclosure are desired to be protected. It will be noted that alternative embodiments of the present disclosure may not include all of the features described yet still benefit from at least some of the advantages of such features. Those of ordinary skill in the art may readily devise their own implementations that incorporate one or more of the features of the present disclosure and fall within the spirit and scope of the present invention as defined by the appended claims.

Claims

1. A cooling system for a machine, comprising:

a first cooling package comprising a first fan and at least one heat exchanger to cool at least one fluid associated with the machine, the first fan configured to rotate in a cooling direction and an opposite cleaning direction,

a second cooling package comprising a second fan and at least one heat exchanger to cool at least one fluid associated with the machine, the second fan configured to rotate in a cooling direction and an opposite cleaning direction, and

a fan control system configured to alternate the first and second fans between a first cleaning mode and a second cleaning mode, wherein, in the first cleaning mode the first and second fans concurrently rotate respectively in their cleaning and cooling directions advancing air in a first flow direction from the first fan to the second fan past the at least one heat exchanger of each of the first and second cooling packages, and, in the second cleaning mode the first and second fans concurrently rotate respectively in their cooling and cleaning directions advancing air in a second flow direction opposite the first flow direction from the second fan to the first fan past the at least one heat exchanger of each of the first and second cooling packages.

2. The cooling system of claim 1, wherein the fan control system is configured to alternate successively the first and second fans between the first cleaning mode and the second cleaning mode during an exchanger-cleaning event.

3. The cooling system of claim 1, wherein in the first cleaning mode the fan control system is configured to command operation of the first fan at at least a predetermined reverse speed threshold for a predetermined period of time, and in the second cleaning mode the fan control system is configured to command operation of the second fan at at least the predetermined reverse speed threshold for the predetermined period of time.

4. The cooling system of claim 3, wherein in each of the first and second cleaning modes the predetermined period of time is cumulative excluding time that the respective first or second fan spends below the predetermined reverse speed threshold.

5. The cooling system of claim 3, wherein the fan control system is configured to abort reversal of the first fan upon occurrence of an abort event, and is configured to begin reversal of the second fan when a speed of the first fan reaches a zero fan speed or at the end of a predetermined period of abort time if the speed of the first fan is below a low-speed threshold.

6. The cooling system of claim 1, wherein the fan control system is configured to alternate successive exchanger-cleaning events between the first cleaning mode and the second cleaning mode.

7. The cooling system of claim 1, wherein the fan control system is configured to operate the first and second fans sequentially in the first cleaning mode, an interim cleaning mode, and the second cleaning mode during an exchanger-cleaning event, and, in the interim cleaning mode, the first and second fans concurrently rotate respectively in their cleaning directions.

8. A machine comprising the cooling system of claim 1, wherein the first and second cooling packages are positioned on laterally opposite sides of a fore-aft axis of the machine such that the first and second flow directions are laterally opposite to one another.

9. The machine of claim 8, wherein the at least one heat exchanger of the first cooling package and the at least one heat exchanger of the second cooling package are positioned laterally between the first and second fans.

10. The machine of claim 9, wherein the machine is a work vehicle.