Patent Grant
8714116
The present invention relates generally to engine cooling fans, and more particularly, an improved engine fan speed control system and method for controlling the engine fan speed of a vehicle fan.
Electronic fan control systems and improvements thereof have been integrated into numerous vehicles to cool motor vehicle components by adjusting the rotation of a fan to control airflow about the components to be cooled. Cooling is necessary across the motor vehicle components to prevent overheating due to variances in internal and external temperatures to the motor and due to load variances placed on the vehicle and its motor components.
The fan is located near the vehicle engine to blow air drawn through engine heat exchangers, radiator, etc. over the top of the engine to carry away heat dissipated from the engine and other motor vehicle components. The fan provides cooling air and improves dissipation of heat for components such as engine coolant, transmission oil, and hydraulic oil. The primary power source for the fan is from the vehicle engine. To reach particular fan speeds and thus provide cooling the motor vehicle components can require significant horsepower draw from the engine, thus reducing engine fuel efficiency.
Electronic fan control systems process temperatures sensed at the various motor vehicle components to determine a desired rotational speed for the fan. The control system commands a clutch to drive the rotation of the fan.
In particular, U.S. Pat. No. 6,772,714 Laird et al. and entitled Electronic Fan Control, is a fan control for receiving inputs from sensors and uses the sensor inputs in determining fan speed. Fan speed in this patent can be controlled according to an alternate coolant temperature table when the PTO is activated and the transmission is in park.
With a vehicle in park, load demand variances on the motor vehicle components are non-existent. Load from an engaged PTO is also constant. With loads held constant across the motor vehicle components while the PTO is engaged and the vehicle is in park, increasing the coolant temperature causes little chance of overheating an engine when trying to reduce fan usage to reduce horsepower consumed by the fan.
What is needed is a fan control system to reduce fan speed, thus reducing horsepower consumed by a fan to reduce engine fuel consumption, but still provide cooling needs across the vehicle motor system when the vehicle is stationary or in motion. This would include selecting a minimum fan speed from calculated fan speed demands based on increased higher coolant temperatures not only when the vehicle is in park, but when the vehicle is moving.
Embodiments of the present invention address and overcome one or more of the above shortcomings and drawbacks, by providing systems, and methods for controlling fan speed in a vehicle. This technology is particularly well-suited for, but by no means limited to, fan control systems in agricultural vehicles.
Embodiments of the present invention are directed to a fan control system for use with a fan cooling system in a vehicle comprising a fan drive for driving a fan blade to rotate at a particular speed. The fan control system further includes one or more sensors for sensing engine conditions and transmission conditions. The fan control system further includes an engine control module coupled to the one or more sensors for receiving engine conditions comprising at least an engine coolant temperature. The engine control module is coupled to a communication link for transmitting engine information comprising engine conditions. The fan control system further includes a transmission control module coupled to the one or more sensors for receiving transmission conditions comprising at least a vehicle speed. The transmission control module is coupled to the communication link for transmitting transmission information comprising transmission conditions. The fan control system further includes a power take off control module coupled to the communication link for transmitting power take off status information. The power take off status information comprises whether a power take off unit on the vehicle is engaged or disengaged. The fan control system further includes a fan control module coupled to the communication link for receiving engine information, transmission information, and power take off status information to process the engine information, the transmission information, and the power take off status information and to generate one or more fan speed demands from the processed information. The fan control module selects from the one or more fan speed demands a maximum fan speed demand to command the fan drive to rotate the fan blade at a commanded rotational fan speed based on the maximum fan speed demand. The fan control module generates at least one of the fan speed demands by processing the engine coolant temperature, the power take off status information, and the vehicle speed. When the vehicle speed of the vehicle is greater than 0 KPH and the power take off unit is engaged, the fan control module raises a set point of the engine coolant temperature to reduce the fan speed demand processed from the engine coolant temperature, the power take off status information, and the vehicle speed. The communication link connects the engine control module, transmission control module, and power take off control module to the fan control module.
According to one embodiment of the invention, the fan control system further includes a fan speed sensor connected to the fan drive to measure the rotational speed of the fan blade and to communicate the sensed rotational speed of the fan blade to the fan control module. According to one aspect of one embodiment of the invention, the fan control module processes the sensed rotational speed of the fan blade with the engine information, transmission information, and power take off status information to generate the one or more fan speed demands. According to another aspect of one embodiment of the invention, the engine information received by the fan control module comprises ambient air temperature and engine rpm and wherein the fan control module processes a slip heat protection based on the ambient air temperature, the engine rpm, the sensed rotational speed of the fan blade, and the selected fan speed demand. According to another aspect of one embodiment of the invention, the fan control module commands the fan drive to change rotation of the fan blade based on the processed slip heat protection so that the fan drive will not maintain a rotational fan speed of the fan blade so as to overheat beyond design limits of the fan drive. According to another aspect of one embodiment of the invention, the fan control module calculates differences between commanded rotational fan speed and sensed rotational fan speed and modulates the commanded rotational fan speed to reduce the differences.
According to another embodiment of the invention, the engine information received by the fan control module includes an intake manifold temperature. The fan control module processes the intake manifold temperature to generate the one or more fan speed demands.
According to another embodiment of the invention, the engine information received by the fan control module includes a catalyst temperature. The fan control module processes the catalyst temperature to generate the one or more fan speed demands.
According to another embodiment of the invention, the fan control module further comprises a timer that counts to a specified time after the vehicle speed drops below a vehicle speed threshold value. According to one aspect of one embodiment of the invention, the fan control module raises the set point of the engine coolant temperature when the specified time is reached if the power take off unit is engaged. According to another aspect of one embodiment of the invention, the vehicle speed threshold value comprises any speed value less than or equal to 5 KPH and greater than 0 KPH.
According to another embodiment of the invention, the set point of the engine coolant temperature comprises a temperature value less than or equal to engine derate temperature. According to one aspect of one embodiment of the invention, the set point of the engine coolant temperature comprises a temperature value approximately 2 degrees Celsius below engine derate temperature. According to another aspect of one embodiment of the invention, the set point of the engine coolant temperature comprises a temperature value approximately 2 degrees Celsius below engine redline as defined on an instrument cluster.
According to another embodiment of the invention, fan control system further includes an air conditioning system module for transmitting air conditioning system status information. The air conditioning system status information includes whether an air conditioning system in the vehicle is turned on or off. According to one aspect of one embodiment of the invention, the fan control module further includes receiving air conditioning status information and an ambient air temperature from the engine information to generate two fan speed demands. The fan control module calculates a first fan speed demand based on a time since air conditioner last turned on in the air conditioning status information and generates a second fan speed demand based on the ambient air temperature.
According to another embodiment of the invention, the communication link is a CAN-bus. According to another embodiment of the invention, the fan drive is a viscous fan drive.
Embodiments of the present invention are directed to a method for controlling the speed of a fan blade in a fan cooling system of a vehicle. The method includes sensing vehicle motor conditions including engine conditions and transmission conditions at one or more sensors. The method further includes receiving at an engine control module one or more engine conditions, including at least an engine coolant temperature, from the one or more sensors. The method further includes transmitting engine information including engine conditions on a communication link from the engine control module to a fan control module. The method further includes receiving at a transmission control module one or more transmission conditions, including at least a vehicle speed, from the one or more sensors. The method further includes transmitting transmission information including transmission conditions on the communication link from the transmission control module to the fan control module. The method further includes transmitting power take off status information from a power take off control module on the communication link from the power take off control module to the fan control module. The power take off status information is whether a power take off unit on the vehicle is engaged or disengaged. The method further includes receiving engine information, transmission information, and power take off status information at the fan control module. The method further includes processing the engine information, transmission information, and power take off status information at the fan control module. The method further includes generating one or more fan speed demands at the fan control module based on the processed engine information, transmission information, and power take off status information. At least one of the fan speed demands is generated by processing the engine coolant temperature, power take off status information, and vehicle speed. The method further includes raising a set point of the engine coolant temperature by the fan control module to reduce the fan speed demand processed from the engine coolant temperature, the power take off status information, and the vehicle speed when the vehicle speed of the vehicle is greater than 0 KPH and the power take off unit is engaged. The method further includes selecting at the fan control module a maximum fan speed demand from the one or more fan speed demands. The method further includes commanding from the fan control module a fan drive to rotate a fan blade connected with the fan drive at a commanded fan speed based on the maximum fan speed demand selected by the fan control module.
According to one embodiment of the invention, the method further includes sensing a rotational fan speed by a fan speed sensor connected with the fan blade and transmitting the sensed speed of the fan to the fan control module from the fan speed sensor. According to one aspect of one embodiment of the invention, the fan control module modifies commanded fan speed based on received sensed fan speed from the fan speed sensor.
According to another embodiment of the invention, the method further includes sensing a gear selected in the transmission system at the one or more sensors, receiving the gear selected in the transmission system at the transmission control module from the one or more sensors, and transmitting the gear selected in the transmission system on the communication link from the transmission control module to the fan control module. According to one aspect of one embodiment of the invention, generating one or more fan speed demands comprises processing the engine coolant temperature, power take off status information, and the selected gear from the transmission information.
According to another embodiment of the invention, the method further includes reducing heat dissipating from the fan drive beyond fan drive design limits by replacing the fan speed command with a lower or higher speed command to the fan drive from the fan control module.
According to another embodiment of the invention, the raising a set point of the engine coolant temperature step further comprises counting a time down to zero after the vehicle speed drops below a vehicle speed threshold and raising the set point when the time reaches zero. According to one aspect of one embodiment of the invention, the vehicle speed threshold value may be any speed value greater than 0 KPH and less than or equal to 5 KPH. According to another aspect of one embodiment of the invention, the method further includes basing the set point of the engine coolant temperature off an engine torque in the engine information when the time has not reached zero or the power take off unit is disengaged.
Additional features and advantages of the invention will be made apparent from the following detailed description of illustrative embodiments that proceeds with reference to the accompanying drawings.
The foregoing and other aspects of the present invention are best understood from the following detailed description when read in connection with the accompanying drawings. For the purpose of illustrating the invention, there is shown in the drawings embodiments that are presently preferred, it being understood, however, that the invention is not limited to the specific instrumentalities disclosed. Included in the drawings are the following Figures:
The problems in the prior art have motivated the creation of a motor vehicle cooling system incorporating a fan controller and methods to provide cooling needs across the motor of a stationary or moving vehicle, while reducing the horsepower draw of the fan. The fan controller selects a minimum fan speed from calculated fan speed demands based on numerous sensed vehicle motor information. In some embodiments of the invention, fan speed demand is generated from increased higher coolant temperatures whether the vehicle is in motion or in park.
A portion of the engine 12 is shown to the right of connection with a fan pulley assembly 20. The engine 12 may be an internal combustion type engine. The engine 12 is connected to a radiator 14 by a pair of interconnecting hoses, inlet hose 16a and outlet hose 16b, in which liquid coolant travels from the engine 12 to the radiator 14 via inlet hose 16a and back via outlet hose 16b.
A viscous fan drive 50 is placed in the fan cooling system 10, between the engine 12 and radiator 14 and the two connection hoses, inlet hose 16a and outlet hose 16b. The viscous fan drive 50 includes an electrical actuator assembly 70. The electrical actuator assembly 70 is connected to an electrical pin connection 74 via an electrical conduit 72 housing one or more electrical wires (not shown). Pin leads at the pin connection 74 are further connected to power supply modules (not shown) and grounding located elsewhere in the vehicle. Other pin leads are connected to a fan control module 200, further described with reference to
The viscous fan drive 50 also includes an input member 60 housing an internal clutch plate (not shown) and the input shaft 62. The input shaft 62 is mounted to the fan pulley assembly 20, as shown in
The input shaft 62 is then mounted to an engine coolant pump 26, both of which are driven by the fan pulley assembly 20. The fan pulley assembly 20 includes a top pulley 24a and bottom pulley 24b connected via belt 22. Engine 12 drives bottom pulley 24b to rotate belt 22 driving top pulley 24a. Top pulley 24a drives input shaft 62 to rotate fan 52. Speed available for bottom pulley 24b is limited by engine rpm. Therefore, fan 52 maximum speed depends on the engine rpm operating at full throttle. Engine 12 operating at lesser rpm, below full throttle or at idle, means the fan 52 will rotate at lesser speeds from maximum. Since a fan 52 rotating at lesser speeds from maximum may not provide for sufficient means to cool the vehicle motor due to increased temperatures or variances in loads when commanded to certain speeds by the fan control module 200, the fan control module 200 will communicate with an engine control module 120, as further described with reference to
In other embodiments of the invention, different types of fan control configurations may be utilized in the fan cooling system 10, other than the viscous fan drive 50 described above. For example, a variable sheave fan drive may be utilized wherein the variable adjustments to fan rotation are conducted by an electronic controller by varying the diameter of pulleys connected to the fan and engine. Another fan drive that may be utilized is a hydraulic fan drive. A hydraulic fan drive includes a dedicated hydraulic engine driven by an electronically controlled variable pressure pump and fixed displacement motor driving the rotational speed of the fan. In particular, a hydraulic pump may include a dependant electro-proportional pressure control, wherein the pump pressure is controlled inversely proportional to the current through a control valve solenoid. The pump will increase displacement to satisfy system demand when the pump pressure drops below a pressure set via the solenoid current. When the pump pressure reaches the set pressure, the pump will adjust its displacement to match required system flow. Another fan drive that may be utilized is an electric fan or array of electric fans.
The engine control module 120 communicates with engine 12 via an electrical connection. The engine control module 120 may command certain aspects of the engine 12 to change, as for example the engine throttle. The engine control module 120 provides the fan control module 200 with various engine information. The information may be relayed to the fan control module 200 regularly and continuously, or at various events or after certain thresholds have been surpassed. One or more of the engine information passed from the engine control module 120 to the fan control module 200 relates to sensed engine conditions, such as sensed temperatures. In one embodiment of the invention, shown in
As shown, the transmission control module 170 communicates with the vehicle transmission system (not shown) via an electrical connection. The transmission control module 170 provides the fan control module 200 with various transmission information. The information may be relayed to the fan control module 200 regularly and continuously, or at various events, or after certain thresholds have been surpassed. One or more of the transmission information passed from the transmission control module 170 to the fan control module 200 relates to sensed transmission conditions, including temperatures. In the illustrated embodiment, four sensed inputs received by the transmission control module 170 from transmission sensors 150 in or in proximity to the transmission system. Transmission oil is provided by a transmission oil temperature sensor 152. In some embodiments of the invention, the transmission oil temperature is sensed at an oil filter head in the transmission system. Hydraulic oil temperature is provided from a hydraulic oil temperature sensor 154. Vehicle speed is provided by a vehicle speed sensor 156. The vehicle speed sensor 156 may be located in proximity to the transmission system or wheels. The speed sensor 156 may also be incorporated into a GPS unit on the motor vehicle providing the sensed speed across a communication connection, as for example a CAN-bus. Transmission gear selection is provided by a transmission gear selection sensor 158. In other embodiments of the invention, additional or alternative sensor information may be provided to the transmission control module 170 and then may be relayed to the fan control module 200, as for example, hydrostatic oil temperature, which is sensed transmission oil temperature at a continuously variable transmission (CVT) hydrostatic inlet of the transmission system.
The power take off module 180 provides the fan control module 200 with PTO status information, in particular when the PTO is either engaged or disengaged. The information may be relayed to the fan control module 200 regularly and continuously, or at various events, or after certain thresholds have been surpassed.
The air conditioning (AC) system module 185 provides the fan control module 200 with AC status information, in particular when the AC was turned on and off, and/or the time expiration since the AC was last turned on or off. In other embodiments of the invention, the AC system 185 may alternatively or in addition provide AC set temperature, temperature sensed at or in proximity to the AC system module 185, and/or refrigerant high side and low side pressures. The information may be relayed to the fan control module 200 regularly and continuously, or at various events, or after certain thresholds have been surpassed.
The fan control module 200 also commands the viscous fan drive 50 to operate at a particular speed and receives sensed speed information from a fan speed sensor 80. The fan control module 200 may compare received sense speed with fan speed command sent to the fan drive 50. In some embodiments of the invention, the fan control module 200 may constantly, or at predetermined intervals, calculate differences between sensed speed and commanded speed. The fan control module 200 may also continuously try and reduce those differences. In other embodiments of the invention, the fan control module 200 may only process input information to derive a speed command in the instance that at least one of the inputs has changed. In other embodiments of the invention, the fan control module 200 may continuously process input information, whether any input signal has changed or not, to continuously derive a speed command and/or confirm that previously processed and transmitted speed commands were correct. By continuously processing input signals, regardless of change, the fan control module 200 can compare the speed command to fluctuations in fan speed provided by the fan speed sensor 80 and reduce differences if needed.
The fan control module 200 may monitor for any errors or faults when comparing the fan speed command with the received sense speed. For example, fan control module 200 may flag a failure and generate a failure message to the other control modules within the vehicle across the CAN-bus 190 or alert the operator of the vehicle. In some embodiments of the invention, a failure may set, as determined by the fan control module 200, when the speed sensed by the fan speed sensor 80 fails to achieve the desired fan speed as commanded to the viscous fan drive 50 after a predetermined amount of time. In other embodiments of the invention, a failure may set, as determined by the fan control module 200, when the speed sensed by the fan speed sensor 80 fails to climb or drop at a preferred rate after the desired fan speed is commanded to the viscous fan drive 50. In other embodiments of the invention, the operator may set the speed command to the viscous fan drive 50.
The fan control module 200 can be one or more microcomputers, microcontrollers, or processors including appropriate peripherals such as memory, power source, data buses, and other circuitry appropriate for carrying out its functionality. The fan control module 200 can use memory to store data (e.g. saved settings, recorded status information, configuration files, user profiles, etc) or instructions (e.g. applications, algorithms, or programs used in the operation of the present invention) for use during operation of the cooling system 10. Memory (not shown) is accessible to fan control module 200 and can be a local RAM, ROM, flash memory, hard drive, solid state storage, removable memory, or any combination or subset thereof.
The fan control module 200 can be a single unit located near or in proximity to the viscous fan drive 50 or anywhere else in the vehicle. The fan control module 200 may be part of a larger electronic control circuit interconnected and located within the engine control module 120, transmission control module 170, packaged together with either or both modules, or stand alone.
The fan control module 200 processes the various inputs transmitted from the CAN-bus 190. Input information provided by the CAN-bus is forwarded to one or more logic modules, in the fan control module 200, containing either software or hardware logic algorithms such as comparators, logic gates, table look-up arrays, mathematical implements, and any other logic types for processing the related inputs. The logic modules may contain their own microcomputers, microcontrollers, processors, memory, or any other computing component to perform functions further described below. These logic modules, each described more fully below, generate fan speed demand as a function of processing inputs entering the particular logic module. The logic modules are capable of determining demands from one or more of these inputs. The fan speed demand generated at every logic module equates to the minimum fan speed required based on the inputs into the module.
A priority logic module 270, housed within the fan control module, selects the highest fan speed demands outputted from the logic modules supplying fan speed demands. As shown in
Each fan speed demand input to the priority logic module 270 is a functional outcome of the one or more control demand logic modules integrated into the fan control module 200. Each control demand logic module determines a fan speed demand based on one or more input signals transmitted to the fan control module 200.
As shown in
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The proportional integral coolant control logic module 260 incorporates a proportional and integral control loop with a feed forward term, wherein the coolant temperature set point is selected based on the operation state of the tractor.
In other embodiments of the invention, the proportional integral coolant control logic module 260 utilizes transmission gear selection in addition to or in alternative to vehicle speed. In other embodiments of the invention, the proportional integral coolant control logic module 260 may also receive fan speed, provided by the fan speed sensor 80. The proportional integral coolant control logic module 260 may then monitor the fan speed directly so as to immediately adjust the fan speed demand F if engine coolant temperature is varying or surpassing specified temperatures significantly impacting the performance of the engine 12.
In other embodiments of the invention, a more accurate sensed reading of coolant temperature provided to the proportional integral coolant control logic module 260 allows for the module 260 to ascertain needed adjustments to the coolant temperature set point so that the fan control module 200 can react faster to set the fan speed command and improve the efficiency of the fan cooling system. For example, if the coolant temperature was sensed with improved resolution such as reading 102.6 degrees Celsius rather than 102 degrees Celsius, then the proportional integral coolant control logic module 260 could react faster as fluctuations of the temperature at a tenths or hundredths degree occurred.
By implementing the functionality described above for operating the coolant temperature at the higher set point, with the PTO engaged and tractor still in motion, thus in a stable low speed condition, a more efficient cooling operation is conducted in the fan cooling system 10. In other embodiments of the invention, a higher coolant temperature set point is selected when the PTO is engaged and the vehicle speed is 0 kph.
Referring back to
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The viscous fan drive 50 also requires cooling. When air temperature flowing over the viscous fan drive 50 restricts cooling to the fan drive 50 a reduction in the amount of heat dissipating from the fan drive 50 is needed. The slip heat protection module 280 prevents the fan drive clutch from trying to maintain a fan speed wherein the clutch dissipates more heat than the design limits of the clutch. The final fan speed demand transmitted from the slip heat protection module 280 is a function of the received fan speed, received engine rpm, received ambient air temperature, and calibration limits preprogrammed and stored into the slip heat protection module 280.
In other embodiments of the invention, a hydraulic fan drive, variable sheave fan drive, or electric fans may be incorporated into fan cooling system 10, in alternative to the viscous fan drive 50 represented in the this embodiment of the invention. As shown in
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Although the invention has been described with reference to exemplary embodiments, it is not limited thereto. Those skilled in the art will appreciate that numerous changes and modifications may be made to the preferred embodiments of the invention and that such changes and modifications may be made without departing from the true spirit of the invention. It is therefore intended that the appended claims be construed to cover all such equivalent variations as fall within the true spirit and scope of the invention.
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