Patent Publication Number: US-10316730-B2

Title: System and method for controlling an engine cooling fan

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a Divisional of U.S. patent application Ser. No. 14/139,078, filed Dec. 23, 2013, the entire contents of which are hereby incorporated by reference. 
    
    
     BACKGROUND 
     The present invention relates to a system and method for controlling one or more fans configured to promote the cooling of an internal combustion engine. 
     Engine cooling systems typically include one or more heat exchangers (e.g., a radiator, a charge-air cooler, an oil cooler, etc.) and one or more fans. The heat exchanger(s) and the fan(s) are configured to cool the internal combustion engine and/or fluids associated with the internal combustion engine. 
     SUMMARY 
     In some embodiments, the invention provides a cooling system for a vehicle engine, wherein the cooling system is powered by a power source and includes a heat exchanger, a system controller, a motor electrically connected to the power source, a fan driven by the motor, and a motor controller. The motor controller is electrically connected to the system controller, the power source and the motor, and is configured to receive power from the power source, receive an enable signal from the vehicle, and to receive a control signal from the system controller. Upon receiving the control signal, the motor controller operates the motor at a first speed based on the control signal. If the first control signal is not received, but the enable signal is received, the motor controller operates the motor at a second speed. 
     Some embodiments of the present invention provide a method of operating a cooling system for a vehicle engine, wherein the cooling system includes a motor operable to rotate a fan. The method includes determining if a control signal has been received; operating the motor to rotate the fan at a first speed if the control signal has been received, wherein the first speed is based on the control signal; and operating the motor to rotate the fan at a second speed if the control signal has not been received. 
     Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a cooling system for a vehicle engine according to one embodiment of the invention. 
         FIG. 2  is a block diagram of a control system of the cooling system of  FIG. 1 . 
         FIG. 3  is a flow chart illustrating a process of the cooling system of  FIG. 1 . 
         FIG. 4  is perspective view of certain portions of the cooling system of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the accompanying drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. 
       FIG. 1  is a perspective view of a cooling system  100  for use in an internal combustion engine driven vehicle. The cooling system  100  includes an assembly of heat exchangers  105  and motor and fan assemblies  110 . The cooling system  100  cools, for example, an internal combustion engine such as a vehicle engine (not shown). 
     The assembly of heat exchangers  105  is shown in greater detail in  FIG. 4 , and includes a radiator  106  and a charge-air cooler  107 . The radiator  106  cools a liquid engine coolant that is pumped through a cooling jacket of the internal combustion engine in order to regulate the engine temperature. The illustrated radiator  106  includes an inlet  115 , an outlet  120 , and a core  125 . In operation, warm liquid enters the radiator  106  via the inlet  115 . The warm liquid passes through a series of tubes of the core  125 . As the liquid passes through the core  125 , heat from the liquid is rejected to air passing over the tubes and the liquid is cooled. The cooled liquid exits the radiator  106  via the outlet  120 . The charge-air cooler cools a flow of pressurized combustion air for the internal combustion engine. The illustrated charge air cooler includes an inlet  116 , an outlet  121 , and a core  126 . In operation, hot charge-air enters the charge-air cooler via the inlet  116 . The hot charge-air passes through a series of tubes of the core  126 . As the charge-air passes through the core  126 , heat from the charge-air is rejected to air passing over the tubes and the charge-air is cooled. In some embodiments, additional heat exchangers such as, for example, oil coolers, transmission coolers, refrigerant condensers, and the like can also be included within the assembly of heat exchangers  105 . 
     The motor and fan assemblies  110  circulate air through the assembly of heat exchanger  105  (for example the core  125  of the radiator  106  and the core  126  of the charge-air cooler  107 ) to provide the necessary cooling air. The assemblies  110  each include a fan  130 , a motor  135 , and a motor controller  140 . Although shown in the illustrated embodiment as including eight motor and fan assemblies  110 , the cooling system  100  may have one or any other number of motor and fan assemblies  110 . In some embodiments, a subset of the fan assemblies  110  can be dedicated to each of the heat exchangers within the assembly of heat exchanger  105 , so that the rate of cooling within each of the heat exchangers can be controlled independently of the rate of cooling of the other heat exchangers. For ease of description, only one of the motor and fan assemblies  110  is described hereinafter, although it will be understood that the description can apply to any number of the other motor and fan assemblies  110 , if present. 
     The motor  135  rotates the fan  130 . The motor  135  is an electrical motor, such as but not limited to a direct-current motor operable at variable speeds. In some embodiments, the motor  135  is a brushless direct-current (BLDC) motor. In other embodiments, the motor  135  can be a variety of other types of motors, including but not limited to a brush DC motor, a stepper motor, a synchronous motor, or other direct-current or alternating-current motors. 
     The motor controller  140  operates the motor  135 . The motor controller  140  includes a plurality of electrical and electronic components that provide power, operational control, and protection to the components and modules within the motor controller  140  and/or the motor  135 . For example, the motor controller  140  includes, among other things, a processing unit (e.g., a microprocessor, a microcontroller, or another suitable programmable device) and a memory unit. In some embodiments, the motor controller  140  is implemented partially or entirely on a semiconductor (e.g., a field-programmable gate array [“FPGA”] semiconductor) chip, such as a chip developed through a register transfer level (“RTL”) design process. In one example, upon receiving a control signal, the motor controller  140  controls and/or operates the switching of a plurality of electronic switches (e.g., FETs), in order to selectively drive the motor  135  at a speed. In some embodiments, the motor controller  140  and the motor  135  form a single unit. In other embodiments, the motor controller  140  and the motor  135  are individual components of the motor and fan assembly  110 . 
     The motor controller  140  includes a plurality of connections (e.g., inputs, outputs, input/outputs, etc.). In some embodiments, the plurality of connections include a control signal connection, a battery positive connection, a battery negative (e.g., ground) connection, an enable signal connection, and a diagnostic connection. 
     The cooling system  100  further includes a system controller  150 . The system controller  150  is in communication with the motor controllers  140  through at least some of the plurality of connections of each of the motor controllers  140 . For example, the system controller  150  and a motor controller  140  can communicate along a control signal connection and a diagnostic connection. 
       FIG. 2  is a block diagram illustrating a control system  200  of the cooling system  100 . The control system  200  includes the system controller  150 . The system controller  150  is electrically and/or communicatively connected to a variety of modules or components of the control system  200  and cooling system  100 . For example, the illustrated system controller  150  is connected to the motor controller  140 , a power supply module  210 , a communications module  215 , and one or more sensors  220 . The system controller  150  can include combinations of hardware and software that are operable to, among other things, control the operation of the cooling system  100 , and specifically, the motor and fan assembly  110  of the cooling system  100 . 
     The system controller  150  can include a plurality of electrical and electronic components that provide power, operational control, and protection to the components and modules within the system controller  150  and/or the cooling system  100 . For example, the system controller  150  includes, among other things, a processing unit  225  (e.g., a microprocessor, a microcontroller, or another suitable programmable device) and a memory  230 . In some embodiments, the system controller  150  is implemented partially or entirely on a semiconductor (e.g., a field-programmable gate array [“FPGA”] semiconductor) chip, such as a chip developed through a register transfer level (“RTL”) design process. 
     The memory  230  includes, for example, a program storage area and a data storage area. The program storage area and the data storage area can include combinations of different types of memory, such as read-only memory (“ROM”), random access memory (“RAM”) (e.g., dynamic RAM [“DRAM”], synchronous DRAM [“SDRAM”], etc.), electrically erasable programmable read-only memory (“EEPROM”), flash memory, a hard disk, an SD card, or other suitable magnetic, optical, physical, or electronic memory devices. The illustrated processing unit  225  is connected to the memory  230  and executes software instructions that are capable of being stored in a RAM of the memory  230  (e.g., during execution), a ROM of the memory  230  (e.g., on a generally permanent basis), or another non-transitory computer readable medium such as another memory or a disc. Software included in some implementations of the cooling system  100  can be stored in the memory  230  of the system controller  150 . The software can include, for example, firmware, one or more applications, program data, filters, rules, one or more program modules, and other executable instructions. The system controller  150  is configured to retrieve from memory and execute, among other things, instructions related to the control processes and methods described herein. In other constructions, the controller  150  includes additional, fewer, or different components. 
     The illustrated power supply module  210  receives power from a power supply and outputs a nominal DC voltage to the system controller  150  and optionally to other components or modules of the cooling system  100 . In some embodiments, the power supply module  240  may receive power from one or more batteries or battery packs, and may receive that power by way of a vehicle ignition system. In some embodiments, the one or more batteries or battery packs further provide power to a vehicle and components of the vehicle. In other embodiments, the power supply module  210  may receive power from other grid-independent power sources (e.g., a solar panel, etc.). 
     In the illustrated embodiment, a vehicle ignition system  240  is electrically connected to and outputs a nominal DC voltage (e.g., 5V, 10V, 20V, 24V, etc.) to the motor controller  140 . In some embodiments, the voltage output by the vehicle ignition system  240  functions as an enable signal. In some embodiments, the vehicle ignition system  240  is electrically connected to the motor controller  140  at a vehicle ignition connection of the motor controller  140 . The motor controller  140  is also electrically connected to one or more batteries  235  via a battery positive connection and a battery negative (e.g., ground) connection. In some embodiments the batteries  235  can be replaced by an alternate power source. 
     The communications module  215  provides analog and/or digital communications from the system controller  150  to outside devices. In some embodiments, the communications module  215  outputs diagnostic information concerning the controller  150  and/or other components of the cooling system  100 . The communications module  215  may include an output driver in the form of a digital driver such as SAE J1939 or CAN bus for communicating directly to the vehicle&#39;s data bus, or the communications module  215  may generate another suitable analog or digital signal depending on the needs of the specific application. 
     The one or more sensors  220  sense any number of a variety of characteristics of the cooling system  100  and the internal combustion engine. For example, the one or more sensors  220  can sense characteristics of the motor  135 , including but not limited to rotational speed, torque, power, voltage, current, and temperature. In some embodiments, the one or more sensors  220  include one or more temperature sensors configured to sense, for example, a temperature of the cooling system  100 , a temperature of the radiator  106  or portions of the radiator  106 , a temperature of the charge-air cooler  107  or portions of the charge-air cooler  107 , and/or a temperature of the internal combustion engine being cooled. 
     In operation, the system controller  150  outputs a control signal to the motor controller  140 . The motor controller  140  receives the control signal and operates the motor  135  based on the control signal. In some embodiments, the control signal is a pulse-width modulated signal. The pulse-width modulated signal can have a duty cycle (e.g., 10%, 50%, 100%, etc.). In some embodiments, the duty cycle corresponds to an operating speed of the motor  135  (e.g., 10% of full speed, 50% of full speed, 100% of full speed, etc.). 
     In some embodiments, during a standby mode the controller  150  will output a standby control signal (e.g., a control signal having a 3% duty cycle) having a standby speed. Thus, during the standby mode, the motor controller  140  will receive the standby control signal from the controller  150  and operate the motor  135  at the predetermined standby speed based on the standby control signal. In some such embodiments the standby speed is zero. 
     During operation, the system controller  150  receives one or more sensed characteristics from the one or more sensors  220 . The system controller  150  may output a different control signal to the motor controller  140  based on the one or more sensed characteristics. For example, the system controller  150  may receive a temperature of the cooling system  100  or various components of the cooling system  100 . The system controller  150  may increase, decrease, or maintain the operating speed of the motor  135  by outputting a control signal based on the received temperature(s). The system controller  150  may output a first control signal to a first motor controller  140 , and a second control signal different in value from the first control signal to a second motor controller  140 . 
     If during operation the motor controller  140  receives an enable signal from the vehicle ignition system  240  but does not receive a control signal (e.g., a normal control signal or a standby control signal) from the system controller  150 , or in some embodiments receives a control signal having a 0% duty cycle, the motor controller  140  waits for a predetermined time (e.g., three-seconds, five-seconds, ten-seconds, etc.) and then operates the motor  135  at a predetermined speed (e.g., a default speed of approximately 3750 RPM). In alternative embodiments, the motor controller  140  does not wait for a predetermined time (after failing to receive a control signal or a control signal having a 0% duty cycle) to operate the motor  135  in such a manner, and instead immediately operates the motor  135  at the predetermined speed. 
     Chart 1 below illustrates an example operation of the cooling system  100 , including whether the motor and fan assembly  110  is receiving a control signal from the system controller  150  and/or is receiving a control signal from the vehicle ignition system  240 , and the corresponding operation of the motor and fan assembly  110 . In operation, when the motor and fan assembly  110  does not receive either of a control signal from the system controller  150  and an enable signal from the vehicle ignition system  240 , the motor and fan assembly  110  operates the motor  135  at zero RPMs. If the motor and fan assembly  110  does not receive a control signal from the system controller  150 , but receives an enable signal from the vehicle ignition system  240 , the motor and fan assembly  110  operates the motor  135  at a predetermined speed (e.g., 3750 RPMs). If the motor and fan assembly  110  receives a control signal from the system controller  150  but does not receive an enable signal from the vehicle ignition system  240 , the motor and fan assembly  110  operates the motor  135  at a speed according to the control signal from the system controller  150 . Such an operation may occur if there is a failure of the vehicle ignition system  240 , or an issue with the wiring between the vehicle ignition system  240  and the motor and fan assembly  110 . If the motor and fan assembly  110  receives a control signal from the system controller  150  and receives an enable signal from the vehicle ignition system  240 , the motor and fan assembly  110  operates the motor  135  at a speed according to the control signal from the controller  150 . 
     
       
         
           
               
               
               
             
               
                   
               
               
                   
                 Enable Signal from 
                   
               
               
                 Control Signal from 
                 Vehicle Ignition 
                 Motor &amp; Fan Assembly 
               
               
                 system Controller 150 
                 System 240 
                 110 Status 
               
               
                   
               
             
            
               
                 OFF 
                 OFF 
                 OFF 
               
               
                 OFF 
                 ON 
                 Operates at predetermined 
               
               
                   
                   
                 speed (e.g., 3750 RPMs). 
               
               
                 ON 
                 OFF 
                 Operates at speed according 
               
               
                   
                   
                 to control signal. 
               
               
                 ON 
                 ON 
                 Operates at speed according 
               
               
                   
                   
                 to control signal. 
               
               
                   
               
            
           
         
       
     
     In embodiments having more than one motor and fan assembly  110 , such as the illustrated embodiment, the system controller  150  may be operable to output a plurality of control signals, each having different duty cycles, to the plurality of motor controllers  140 . Thus, the system controller  150  can be operable to control the various motor and fan assemblies  110  at different speeds, or one or more motor and fan assemblies  110  at a standby speed. For example, the system controller  150  may operate a first motor and fan assembly  110  at a first speed, a second motor and fan assembly  110  at a second speed, and a third motor and fan assembly  110  at a standby speed. 
       FIG. 3  illustrates an operation  300  of the cooling system  100  according to an embodiment of the present invention. The operation  300  begins by the vehicle turning on (Step  305 ). The system controller  150  receives power from a power source (Step  310 ). The system controller  150  receives one or more sensed characteristics (Step  315 ), and outputs a control signal based on at least the one or more sensed characteristics (Step  320 ). The motor controller  140  determines if the control signal has been received (Step  325 ). If the control signal has been received, the motor controller  140  operates the motor  135  based on the control signal (Step  330 ). If the control signal has not been received, the motor controller  140  determines is an enable signal has been received (step  350 ). If an enable signal has been received, the motor controller  140  waits for a predetermined time period (Step  335 ). The motor controller  140  determines if the control signal has been received during the predetermined time period (Step  340 ). If the motor controller  140  has received the control signal within the predetermined time period, the operation  300  proceeds to Step  330 . If the motor controller  150  has not received the control signal within the predetermined time period, the motor controller  140  operates the motor  135  at a predetermined operating speed (e.g., the default speed) (Step  345 ). If during step  350  an enable signal has not been received, then the motor controller  140  does not operate the motor  135 . 
     As one particular advantage of the above described operation, a failure of the system controller  150  does not result in a shut-down of the cooling system  100 , provided that an enable signal from the vehicle ignition system  240  is received by a motor controller  140 . As a result, the vehicle would still be able to be driven to, for example, a garage or repair facility so that the system controller  150  could be replaced. The presence of an electrical connection between the vehicle ignition system  240  and each of the motor controllers  140  is not, however, required for the operation of the cooling system  100  in the case of a non-faulty system controller  150 , so that failure probabilities of the system do not increase by the addition of such a connection. 
     Thus, the invention provides, among other things, a system and method for controlling one or more fans configured to promote the cooling of an internal combustion engine. Various features and advantages of the invention are set forth in the following claims.