Abstract:
A controller area network based climate control system for a work machine, and a method of operation of the same, which advantageously and economically integrates into and utilizes the resources and capabilities of a CAN of a work machine, including, but not limited to, shared data from other systems of the machine, particularly engine data including engine operating speed and temperature, for controlling climate control system operation, as well as for troubleshooting and diagnosing problems.

Description:
[0001]     This application claims the benefit of U.S. Provisional Application No. 60/757,638, filed Jan. 10, 2006. 
     
    
     TECHNICAL FIELD  
       [0002]     This invention relates generally to a climate control system for the interior of an operator platform or cabin of a self-propelled work machine such as a tractor, agricultural harvesting machine, or the like, and more particularly, to a controller area network based climate control system therefor, and a method of operation of the same.  
       BACKGROUND ART  
       [0003]     U.S. Provisional Application No. 60/757,638 filed Jan. 10, 2006 is incorporated herein in its entirety by reference.  
         [0004]     Environmental conditions, such as, but not limited to, temperature, humidity and/or air pressure, within an enclosed operator platform or cabin of a self-propelled work machine are typically controlled or regulated using a climate control system, also commonly referred to as a heating, ventilating and air-conditioning (HVAC) system. The climate control or HVAC system of a work machine typically includes several operator operable controls located within the cabin including, but not limited to, a mode selector, a temperature selector, and a fan speed selector. The mode selector will typically allow selecting a heat mode, an air conditioning mode, a window defrost defog mode, an air recirculation mode, and a fresh air mode. Additionally, some systems may be operable in an automatic temperature control (ATC) mode wherein the system controls the cabin air temperature to or within a range of an operator selectable value. Reference in this regard, Panoushek et al., U.S. Pat. No. 5,993,312, which illustrates a representative HVAC system for a work machine including this latter feature. Still further, some systems may be operable in a mode which automatically controls the fan speed and other elements of the system to maintain the cabin air pressure at a level above that of outside air, to limit infiltration into the cabin of outside air, dust and other contaminants from the outside environment. This feature has particular utility in work machines used in off-road applications such as construction, mining and agricultural applications, and, more particularly, such as agricultural tractors and harvesting machines, which are sometimes operated in very dusty environments, for instance, wherein the dust is so dense as to significantly limit visibility. A cabin pressure sensor may be provided for use in regulating cabin air pressure.  
         [0005]     Operation in such intense dust can cause problems, including for instance, the partial or full clogging of the air intake filter or filters for the cabin, as well as of radiators and heat exchangers, including the air conditioning condenser, which is typically cooled using external air. As a consequence, in the instance of the air-conditioning system, the system may be required to operate for longer periods, and/or more frequently, to achieve or maintain a selected climate setting for the operator cabin. Such dust problems may be sufficiently severe so as to make it impossible for the air-conditioning system to achieve the climate setting. Such conditions, if allowed to exist, can result in increased power usage, system and component degradation and shut-down or failure, downtime for cleaning and/or repair, and operator and/or machine owner dissatisfaction.  
         [0006]     Other conditions that can lead to or result in system, operation and component degradation and failure include, but are not limited to, operation of high electrical current using items such as the cabin air fan when the engine is not operating or is operating at less than an adequate level, drive belt slippage and failure, air-conditioning system refrigerant and oil leakage and internal blockages, coolant leakage in the lines and heat exchanger of the heating system, fan motor failure, sensor failure, cabin seal failure, and control failure.  
         [0007]     Still further, the operation of the climate control system, and, in particular, the compressor of the air-conditioning component thereof driven by the engine of the work machine, can have power requirements which can be significant for a smaller engine, and/or an engine under heavy load, such as when the engine is being started, the work machine is accelerating, going uphill, and/or the engine is powering components such as harvesting and crop processing equipment, load bearing fluid lift cylinders and the like, such that if the air-conditioning compressor is operated, or is allowed to initiate operation, when the engine is under heavy load, the performance of the air-conditioning system, engine, and/or other components powered by the engine, and/or the engine itself, may be degraded.  
         [0008]     It is well known to provide devices in connection with the air-conditioning system operable for sensing a condition or conditions representative of engine load and/or operating conditions, such as the engine intake vacuum and temperature, and devices for automatically controlling the engagement of the air-conditioning compressor clutch and/or the compressor, for avoiding or minimizing overloading the engine and/or degrading operation of the air-conditioning system and other systems of a vehicle. It is also well known to provide sensors, such as thermal sensors and the like, in association with various of the components of the climate control system, and operable for sensing problem conditions and outputting a signal and/or shutting down the system or component when a problem is indicated, for instance, when a component of the system such as the compressor or the condenser is clogged or obstructed, beginning to overheat, or the evaporator is freezing. Such sensors are typically connected to an air-conditioning electronic control unit (ECU), which may be operable for storing information representative of a problem condition in a memory for retrieval for use in diagnosing the problem. The ability to rapidly diagnose problems with work machines is a particularly sought after capability, as downtime for such machines can be costly.  
         [0009]     Presently, the known climate control or HVAC systems in work machines used for off-road applications are stand-alone units having dedicated ECUs. These controllers operate in isolation and do not communicate or interface effectively with other controllers in the vehicle. This isolation has been found to restrict the ability of the HVAC system to optimally use available resources and hence ends up making the HVAC system a higher cost system.  
         [0010]     More recently, it has been observed that work machines commonly utilize controller area networks (CANs) connecting multiple system controllers and operable for sharing both raw and processed data and information, in real-time, relating to a variety of machine systems and components, including information relating to the engine, via the engine controller, to function in a coordinated and integrated fashion. It is also observed that some CANs have a controller including software capable of automatically troubleshooting and diagnosing problems with a system or component on the CAN. It has also been found that, often, a variety of controllers on work machines have under-utilized processing capacity.  
         [0011]     Accordingly, what is sought is a climate control system, and a method of operation of the same, which advantageously and economically integrates into and utilizes the resources and capabilities of a CAN of a work machine, including, but not limited to, shared data from other systems of the machine, particularly engine control data from an engine controller, for controlling climate control system operation, as well as for troubleshooting and diagnosing problems.  
       SUMMARY OF THE INVENTION  
       [0012]     What is disclosed is a controller area network based climate control system for a work machine, and a method of operation of the same, which advantageously and economically integrates into and utilizes the resources and capabilities of a CAN of a work machine, including, but not limited to, shared data from other systems of the machine, particularly engine data including engine operating speed and temperature, for controlling climate control system operation, as well as for troubleshooting and diagnosing problems.  
         [0013]     According to a preferred aspect of the invention, the climate control or HVAC control system is implemented through the use of a CAN bus topology to communicate with others of the vehicle components. In this approach, one or more functions of the HVAC system are distributed to other controllers of the CAN to carry out various tasks. In this way, the CAN networked devices share raw and processed information in real-time to function in a coordinated and integrated fashion. This is preferably implemented using a bidirectional messaging architecture.  
         [0014]     According to another preferred aspect of the invention, the climate control system includes an electronic programmed processor based controller, also referred to as the Automatic Temperature Controller (ATC), which is programmed for automatically controlling the temperature of the air within the cabin interior to within a range of a temperature selected using an input device. The ATC is connected to a CAN of the work machine and is operable for sharing data and information with other controllers and devices on the network, including the engine controller or ECU. Operator input devices can include, for instance, one or more switches, potentiometers, and/or other device connected directly to an input/output port or ports of the ATC, or to another device or controller of the network. Component inputs, such as condenser temperature, evaporator temperature, refrigerant pressure, and the like can be received directly by the ATC through input ports thereof, or by other controllers of the network and shared. This can be determined on an application by application basis and can be configured so as to economize wiring requirements.  
         [0015]     Information such as system status, mode, temperature, and the like is displayed by an instrument cluster unit (ICU) connected to the network, on a display located in the cabin. The ICU and display can also be used for displaying information relating to other systems such as the engine and/or operating or functional systems of the machine, e.g. harvesting systems of a combine, power takeoff system of a tractor, etc., and can be optionally configured to provide an input capability, for instance, for inputting climate control system commands, e.g., temperature, fan speed, mode (A/C, heat, defog) using a touch screen type display device in lieu of using discrete devices such as switches, potentiometers, and the like. The engine controller is operable for sharing engine speed information and also engine temperature on the network. The ATC controller, or another controller on the network, will preferably include a memory, such as a resetable flash type, for temporarily storing information relating to fault conditions or flagged events. The network can include a connector for connection of a diagnostic service tool thereto, to enable quickly troubleshooting and diagnosing problems.  
         [0016]     According to another preferred aspect of the invention, in operation, the ATC controller will monitor the engine speed information shared on the network by the engine controller. The ATC controller will be programmed to prevent initiation of operation of high electrical current drain components, e.g., the cabin air blower or fan, if the engine speed is below a threshold level. This will increase the power available for engine cranking and other tasks. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]      FIG. 1  is a side view of an agricultural windrower including a CAN based climate control system according to the present invention;  
         [0018]      FIG. 2  is a diagrammatic representation of the CAN of the invention;  
         [0019]      FIG. 3  is a simplified schematic representation of an air-conditioning system of the climate control system of  FIG. 1 ;  
         [0020]      FIG. 4  is a diagrammatic representation of operation of the CAN based climate control system of the invention; and  
         [0021]      FIG. 5  is a high-level flow diagram of steps of an operating method of the invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0022]     Turning now to the drawings wherein aspects of a preferred embodiment of a controller area network (CAN) based climate control system  10  of the invention is shown, in  FIG. 1 , system  10  is shown incorporated into an agricultural work machine, which is a self-propelled windrower  12 . Windrower  12  is contemplated to be representative of a wide variety of work machines with which CAN based climate control systems of the present invention can be utilized, which can include, but are not limited to, other harvesting machines, such as combines and cotton pickers, tractors, earth movers, mining machines, off-road trucks, and the like. Windrower  12  includes an engine  14  operable for propelling it through fields from which crops will be cut, while powering a variety of systems thereof, including climate control system  10 , and apparatus of a crop cutting header  16 , including a cutter mechanism  18  extending across a lower forward end thereof, and crop gathering and processing apparatus including a reel, various conveyors, and processing rollers, operation of which are coordinated and controlled by an electronic microprocessor based controller  20  in the well known manner. The propulsion and steering of windrower  12  is controlled by an electronic drive controller  22  which is also a micro-processor based controller and operates fluid motors in driving connection to drive wheels, as represented by wheel  24 . Engine  14  is controlled by an electronic engine control unit (ECU) in the well known manner. A micro-processor based climate control system controller or automatic temperature controller (ATC) of system  10 , the ECU, and optionally controller  20  are connected together by a communications network or bus of the CAN, over which bus data and information are shared. Other systems of a work machine can also be connected to the CAN bus, and can include, but are not limited to, a display controller which is preferably an instrument cluster unit (ICU) connected to a display device  26  located in an interior space  28  of an operator cabin  30  of windrower  12 , and other electronic controllers.  
         [0023]     Referring also to  FIG. 2 , the CAN bus is shown connected to the ATC of climate control system  10 , to the ECU, to the ICU, and to a representative electronic controller, which is representative of controllers of other systems, such as controllers  20  and  22 , which can be connected to the CAN bus. Additionally, a service tool is shown removably connected to the CAN bus via a suitable interface, which can be for instance, a conventional RS  232  plug interface  32 . Climate control system  10  is illustrated configured for operator commands to be inputted to the ATC via suitable input devices connected directly to the ATC, which can include, but are not limited to, conventional rotary or linear potentiometers, switches, and the like, typically located in cabin  30 . Alternatively, system  10  could be configured such that operator inputs will be received via an interactive display device, such as a touchscreen (not shown), in connection with the CAN bus via the ICU.  
         [0024]     The ATC is programmed to output current and/or set system conditions and operating mode information over the CAN bus to the ICU, which, in turn, is programmed to process and display the information on a suitable display device, such as device  26  located within operator cabin  30 . Display device  26  can be, for instance, an LCD or CRT device, and can be configured for displaying such useful climate control system information as cabin blower or fan speed, cabin interior temperature, outside temperature, cabin pressure, and system operating mode, as well as additional information relating to other systems, such as engine speed and temperature, and information from other controllers such as controller  20  for elements of the crop gathering and processing apparatus and/or drive controller  22 . Fault condition information can also be displayed, such as a high temperature condition representative of clogging of a condenser of the system (discussed below). Sensors utilized by the ATC for the operation of the climate control system can be connected directly to the ATC, or to others of the electronic controllers, as denoted by dotted lines in  FIG. 2 .  
         [0025]     Referring also to  FIG. 3 , elements of the air-conditioning system  34  of climate control system  10 , are shown. The ATC is shown connected to the CAN bus, as is another representative electronic controller, in the above-described manner. The ATC is shown also connected to several components of air-conditioning system  34  by suitable conductive paths  36 , which can be, for instance, wires of a wiring harness of the work machine. Such components include, but are not limited to, a compressor clutch  38 , a high pressure valve or sensor  40 , and a low pressure valve or sensor  42 . Other components to be connected to a controller include temperature sensors  44  and  46  which are illustrated by dotted lines as being connected alternatively to the ATC or another electronic controller, to illustrate the flexibility afforded by the present system.  
         [0026]     Compressor clutch  38  is controllable by the ATC to connect a refrigerant compressor  48  of the air-conditioning system with a drive, such as an auxiliary belt drive driven by the engine of the windrower, for compressing refrigerant of the air-conditioning system in the well known manner. The refrigerant will be compressed to a designated high pressure and will flow, as denoted by the arrows, through refrigerant lines  50  which connect to a heat exchanger or condenser  52  of a high pressure side of system  34 . Condenser  52  will typically be located in a rack with other heat exchangers, such as the engine radiator, located in this application near the rear end of engine  14  in  FIG. 1 . Compressor  48  may be located near this end of the engine also.  
         [0027]     Temperature sensor  46  will be a suitable device such as a thermistor and will be positioned for monitoring a temperature of condenser  52 . A high temperature reading from sensor  46  will typically indicate a fault condition, that is, inadequate dissipation of heat therefrom, such as can result from a clogging or blocking of air passages through the condenser with dust. Sensor  46  may be connected by a suitable conductive path  36  directly to the ATC, or, because of its location at the end of the machine, it may be more economical or convenient to connect it to a closer electronic controller on the CAN bus other than the ATC. In either instance, the receiving controller can process the signals, and share information representative of the temperatures over the CAN bus. For instance, information indicating a high temperature condition can be displayed on device  26  to inform an operator that the condenser may need cleaning. The information can also be stored for retrieval with a service tool when connected to the bus.  
         [0028]     High pressure sensor  40  is located in high-pressure side line  50  and is operable for detecting under pressure conditions, and possibly over pressure conditions also, in the high pressure side of the system, and outputting signals representative thereof to the ATC. Again, like sensor  46 , sensor  40  can be connected directly to the ATC, or to another electronic controller on the CAN bus. The ATC can be programmed such that if sensor  40  indicates a pressure problem, the ATC can determine that a fault condition exists and place that information on the bus. And, the ATC, or another of the controllers, can be programmed to diagnose a problem in connection with the sensor, or any of the other sensors connected thereto, such as an open connection, a short, or the like.  
         [0029]     From condenser  52 , the pressurized refrigerant will flow through lines  50  of the high pressure side to a receiver dryer  54 , and from there, through an expansion valve  56 . The refrigerant will exit expansion valve  56  at a lower pressure, and flow at the lower pressure through a low pressure side of the system to a second heat exchanger or evaporator  58 , through which cabin air is directed by a blower fan  60  for cooling the interior space of the cabin in the well known manner.  
         [0030]     Sensor  44 , which also can be a thermistor or other suitable device, is positioned for sensing a temperature condition in relation to evaporator  58 , particularly, temperatures indicative of an ice build up or freezing on the outer surfaces thereof which could impede air flow therethrough. Sensor  44 , like sensor  46 , can be connected by a suitable conductive path  36  directly to the ATC, or it may be more economical or convenient to connect it to another electronic controller on the CAN bus other than the ATC. In either instance, the receiving controller can process the signals, and share information representative of the temperatures over the CAN bus. Again, the ATC, or other of the controllers, can be programmed to diagnose a problem in connection with this sensor, or any of the other sensors connected thereto, such as an open connection, a short, or the like.  
         [0031]     From evaporator  58 , the lower pressure refrigerant will pass through expansion valve  56  en route to compressor  48 , completing a closed loop.  
         [0032]     Referring also to  FIG. 4 , the ATC will also be connected to other sensors, which can include, but are not limited to, a cabin air temperature sensor, an outside air temperature sensor, a cabin air pressure sensor, and/or a light sensor positioned for determining presence of direct sunlight, a fan blower driver  62  ( FIG. 3 ), and one or more actuators including a mode door actuator controllably operable for directing air flows to different regions of the operator cab interior space. Alternatively, as another advantage of the present CAB based system, these devices can be connected to other controllers on the CAB bus. Using information outputted by these and the other above discussed sensors, whether connected directly to the ATC, or shared over the CAB bus, the ATC will be equipped so as to be automatically operable for controlling the temperature of the interior space of the operator cab to or within a range of a set temperature as selected by an operator using conventional input devices such as pushbuttons and rotary knobs, in a selected operating mode, e.g. heat, A/C, defog. The operator will be capable of viewing visual data on the display device driven by the ICU, in real-time, including the current operating mode, blower speed, cabin temperature, outside temperature, and cabin pressure, as well as new operator settings for such data. Additionally, the ATC, or any of the controllers, can be programmed to diagnose a problem in connection with these sensors or actuators, such as an open connection, a short, or other malfunction and store or share information regarding the condition over the CAN bus. And, by connecting a service tool to the CAN interface via the RS 232 plug  32 , such stored information relating to, for instance, current or past system conditions and fault conditions can be retrieved, for problem troubleshooting, diagnosing and repair of any of the systems connected to controllers on the CAB bus.  
         [0033]     Referring also to  FIG. 5 , as another operational advantage of providing shared data over the CAB bus, the ATC can be programmed so as not to turn on high current load devices, for instance, the fan blower driver, or to restrict the operation thereof to lower speed settings, under certain conditions, such as prior to starting of the engine, or when the engine is operating at a speed which is less than a predetermined value, so as to preserve electrical and/or charging system power for other purposes such as cranking the engine for starting. As another desirable feature, the ATC can be programmed such that functions such as conversion from Celsius to Fahrenheit operation can be accomplished by the toggling of a switch connected to any controller on the CAN bus.  
         [0034]     It will be understood that changes in the details, materials, steps, and arrangements of parts which have been described and illustrated to explain the nature of the invention will occur to and may be made by those skilled in the art upon a reading of this disclosure within the principles and scope of the invention. The foregoing description illustrates the preferred embodiment of the invention; however, concepts, as based upon the description, may be employed in other embodiments without departing from the scope of the invention. Accordingly, the following claims are intended to protect the invention broadly as well as in the specific form shown.