Abstract:
A compressor control apparatus for a vehicle includes: a compressor configured to compress coolant of an air conditioner; a coolant temperature measurement unit configured to measure a coolant temperature; a data detector configured to detect state data for controlling the compressor; and a controller configured to determine an operation rate of the compressor based on the coolant temperature and the state data, and operate the compressor based on the operation rate of the compressor.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims under 35 U.S.C. §119(a) the benefit of Korean Patent Application No. 10-2016-0039407 filed in the Korean Intellectual Property Office on Mar. 31, 2016, the entire contents of which are incorporated herein by reference. 
       BACKGROUND 
     (a) Technical Field 
       [0002]    The present invention relates to a compressor control apparatus for a vehicle. 
       (b) Description of the Related Art 
       [0003]    In general, an engine of a vehicle generates a large amount of heat. When a temperature of the engine rises to an appropriate temperature or more, explosion is likely to occur. Thus, in order to cool the engine, coolant for lowering the temperature is circulated around the engine. Heated coolant radiates heat through a radiator, and a cooling fan is installed in an engine room of the vehicle in order to raise a heat radiation effect of the radiator. 
         [0004]    In warm temperatures, when a vehicle travels at high speed along a mountain road or a trailer tows a vehicle and travels with an air conditioner turned on, the engine must be excessively operated. Thus, a coolant temperature of the engine continuously rises. When the coolant temperature rises, the engine may be over-heated. 
         [0005]    In order to prevent the over-heating of the engine, a BLDC (Brushless Direct Current) motor or a high-capacity motor is applied to a cooling fan mounted on a radiator in Europe and North America, and a dual fan is applied in Japan. When the BLDC motor, the high-capacity motor and the dual fan are applied, the material cost increases, and the weight of the vehicle increases. 
         [0006]    In the related art, when the coolant temperature rises to a preset temperature, operation of the air conditioner is stopped. Then, when the coolant temperature falls to a specific temperature due to an operation stop of the air conditioner, the air conditioner is turned on to prevent overheating of the engine. Since the air conditioner is controlled to be repetitively turned on/off according to the coolant temperature, the durability of the engine and the compressor is deteriorated. 
         [0007]    In the related art, when the air conditioner is turned off to control the coolant temperature, an indoor temperature of the vehicle rises. Thus, a driver may feel uncomfortable, and moisture on windows cannot be removed. This moisture on the windows frequently occurs when the outdoor temperature falls while the vehicle travels along a mountain road, thereby having a negative influence on operation safety of vehicle occupants. 
         [0008]    The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. 
       SUMMARY 
       [0009]    The present invention provides a compressor control apparatus and method for a vehicle, which controls a coolant temperature by controlling an operation rate of a compressor when a vehicle state falls within a worst stress condition. 
         [0010]    Further, another embodiment of the present invention provides a compressor control apparatus and method for a vehicle, which controls a coolant temperature by lowering an operation rate of a compressor in order to prevent over-heating of an engine and operation stop of the compressor. 
         [0011]    An exemplary embodiment of the present invention provides a compressor control apparatus for a vehicle, including: a compressor configured to compress coolant of an air conditioner; a coolant temperature measurement unit configured to measure a coolant temperature; a data detector configured to detect state data for controlling the compressor; and a controller configured to determine an operation rate of the compressor based on the coolant temperature and the state data, and operate the compressor based on the operation rate of the compressor. When the state data satisfy a worst stress condition, the controller may determine whether the coolant temperature is equal to or more than a first reference value, and when the coolant temperature is equal to or more than the first reference value, the controller may lower the operation rate of the compressor. 
         [0012]    The worst stress condition may be satisfied when an outdoor temperature is equal to or more than a preset temperature, an air volume level of the air conditioner is equal to or more than a preset level, and a position value of an accelerator pedal is equal to or more than a preset position value. 
         [0013]    When the coolant temperature is equal to or more than the first reference value, the controller may determine the operation rate of the compressor using a first control map in which the operation rate of the compressor is set according to the coolant temperature. 
         [0014]    When the state data do not satisfy the worst stress condition, the controller may determine whether the coolant temperature is equal to or more than a second reference value, and when the coolant temperature is equal to or more than the second reference value, the controller may lower the operation rate of the compressor. The second reference value may be larger than the first reference value. 
         [0015]    The state data may include one or more of an outdoor temperature, an air volume level of the air conditioner, and a position value of an accelerator pedal. 
         [0016]    The data detector may include one or more of: an outdoor temperature sensor configured to measure an outdoor temperature; an accelerator position sensor (APS) configured to measure the position value of the accelerator pedal; and an air volume sensor configured to measure the air volume level of the air conditioner. 
         [0017]    Another exemplary embodiment of the present invention provides a compressor control method for a vehicle, including steps of: detecting state data when an air conditioner is turned on; determining whether the state data satisfy a worst stress condition; comparing a coolant temperature to a first reference value, when the state data satisfy the worst stress condition; lowering an operation rate of the compressor when the coolant temperature is equal to or more than the first reference value; and operating the compressor based on the compressor operation rate. 
         [0018]    The step of determining whether the state data satisfy the worst stress condition may include steps of: determining whether an outdoor temperature is equal to or more than a preset temperature; determining whether an air volume level of the air conditioner is equal to or more than a preset level; and determining whether a position value of an accelerator pedal is equal to or more than a preset position value. 
         [0019]    The worst stress condition may be satisfied when an outdoor temperature is equal to or more than a preset temperature, an air volume level of the air conditioner is equal to or more than a preset level, and a position value of an accelerator pedal is equal to or more than a preset position value. 
         [0020]    The step of lowering the operation rate when the coolant temperature is equal to or more than the first reference value may include determining the operation rate using a first control map in which a compressor operation rate is set according to a coolant temperature, when the coolant temperature is equal to or more than the first reference value. 
         [0021]    The compressor control method may further include steps of: comparing the coolant temperature to a second reference value when the state data do not satisfy the worst stress condition; and lowering the operation rate when the coolant temperature is equal to or more than the second reference value. 
         [0022]    The second reference value may be larger than the first reference value. 
         [0023]    Another exemplary embodiment of the present invention provides a non-transitory computer readable medium containing program instructions executed by a processor, the computer readable medium including: program instructions that detect state data when an air conditioner is turned on; program instructions that determine whether the state data satisfy a worst stress condition; program instructions that compare a coolant temperature to a first reference value, when the state data satisfy the worst stress condition; program instructions that lower an operation rate of a compressor when the coolant temperature is equal to or more than the first reference value; and program instructions that operate the compressor based on the operation rate. 
         [0024]    According to the exemplary embodiments of the present invention, when the vehicle state falls within the worst stress condition, the compressor control apparatus and method may not stop the operation of the compressor, but control the coolant temperature by lowering the operation rate of the compressor. Therefore, the durability of the engine and the compressor can be improved, and over-heating of the engine can be prevented. 
         [0025]    Further, since the compressor control apparatus and method can control the coolant temperature without adding separate hardware, any increases in material costs and weight can be prevented, and fuel efficiency can be improved. 
         [0026]    The other effects which can be obtained or expected by the exemplary embodiments of the present invention will be directly or implicitly disclosed in the detailed descriptions of the present invention. That is, various effects which are expected according to the exemplary embodiments of the present invention will be disclosed in the detailed descriptions of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]      FIG. 1  is a schematic diagram illustrating a compressor control apparatus for a vehicle according to an exemplary embodiment of the present invention. 
           [0028]      FIG. 2  is a flowchart illustrating a compressor control method for a vehicle according to an exemplary embodiment of the present invention. 
           [0029]      FIG. 3  is a diagram illustrating a first control map according to the exemplary embodiment of the present invention. 
           [0030]      FIG. 4  is a diagram illustrating a second control map according to the exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0031]    It is understood that the term “vehicle” or “vehicular” or other similar term as used herein is inclusive of motor vehicles in general such as passenger automobiles including sports utility vehicles (SUV), buses, trucks, various commercial vehicles, watercraft including a variety of boats and ships, aircraft, and the like, and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other alternative fuel vehicles (e.g. fuels derived from resources other than petroleum). As referred to herein, a hybrid vehicle is a vehicle that has two or more sources of power, for example both gasoline-powered and electric-powered vehicles. 
         [0032]    The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Throughout the specification, unless explicitly described to the contrary, the word “comprise” and variations such as “comprises” or “comprising” will be understood to imply the inclusion of stated elements but not the exclusion of any other elements. In addition, the terms “unit”, “-er”, “-or”, and “module” described in the specification mean units for processing at least one function and operation, and can be implemented by hardware components or software components and combinations thereof. 
         [0033]    Further, the control logic of the present invention may be embodied as non-transitory computer readable media on a computer readable medium containing executable program instructions executed by a processor, controller or the like. Examples of computer readable media include, but are not limited to, ROM, RAM, compact disc (CD)-ROMs, magnetic tapes, floppy disks, flash drives, smart cards and optical data storage devices. The computer readable medium can also be distributed in network coupled computer systems so that the computer readable media is stored and executed in a distributed fashion, e.g., by a telematics server or a Controller Area Network (CAN). 
         [0034]    Hereafter, the operation principle of a compressor control apparatus and method for a vehicle according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings. However, the following drawings and detailed descriptions relate to one exemplary embodiment among a variety of exemplary embodiments for effectively describing the features of the present invention. Therefore, the present invention is not limited to the drawings and the detailed descriptions. 
         [0035]    Hereafter, an exemplary embodiment of the present invention will be described in detail as follows with reference to the accompanying drawings. 
         [0036]      FIG. 1  is a schematic diagram illustrating a compressor control apparatus for a vehicle according to an exemplary embodiment of the present invention. 
         [0037]    Referring to  FIG. 1 , the compressor control apparatus  100  according to the exemplary embodiment of the present invention includes a compressor  50 , a coolant temperature measurement unit  110 , a data detector  120 , a controller  150 , and a storage unit  160 . 
         [0038]    The compressor  50  actuates an air conditioner by compressing coolant existing in the air conditioner at high temperature and high pressure. The compressor  50  may be operated according to an operation rate determined by the controller  150 . As the operation rate of the compressor  50  is increased, the cooling performance of the air conditioner is increased. 
         [0039]    The coolant temperature measurement unit  110  measures the temperature of coolant, and provides the measured coolant temperature to the controller  150 . 
         [0040]    The data detector  120  detects state data for controlling the compressor  50 . The data detector  120  includes an outdoor temperature sensor  133 , an accelerator position sensor (APS)  135  and an air volume sensor  137 . 
         [0041]    The outdoor temperature sensor  133  measures an outdoor temperature of air outside the vehicle. The outdoor temperature sensor  133  provides the measured outdoor temperature to the controller  150 . 
         [0042]    The APS  135  measures the extent that a driver steps down an accelerator pedal. The APS  135  measures the position value of the accelerator pedal (the extent that the accelerator pedal is depressed), and provides the measured position value to the controller  150 . When the accelerator pedal is completely depressed, the position value of the accelerator pedal is 100%, and when the accelerator pedal is not depressed, the position value of the accelerator pedal is 0%. Instead of the APS  135 , a throttle valve opening detector mounted on an intake path may be used. 
         [0043]    The air volume sensor  137  measures the level of the air volume of the air conditioner, and provides the measured level to the controller  150 . 
         [0044]    The controller  150  controls the operation of the compressor  50 , the coolant temperature measurement unit  110 , the data detector  120 , and the storage unit  160 . The controller  150  receives the state data from the data detector  120 . The state data for controlling the compressor  50  include one or more of an outdoor temperature, a position value of the accelerator pedal, and an air volume level of the air conditioner. 
         [0045]    When the state data satisfy the worst stress condition, the controller  150  checks the coolant temperature measured through the coolant temperature measurement unit  110 . The controller  150  checks whether the coolant temperature is equal to or more than a first reference value. The first reference value may indicate a reference value for lowering the operation rate of the compressor  50 , and be set to 108° C. When the coolant temperature is equal to or more than the first reference value, the controller  150  determines the compressor operation rate according to the coolant temperature. The controller  150  controls the operation of the compressor  50  based on the compressor operation rate. 
         [0046]    The controller  150  may include one or more microprocessors which are operated by a predetermined program, and the predetermined program may include a series of commands for performing the respective steps included in a compressor control method according to an exemplary embodiment of the present invention, which will be described below. The compressor control method will be described in detail with reference to  FIGS. 2 to 4 . 
         [0047]    The storage unit  160  stores data required by the constituent elements of the compressor control apparatus  100  and data generated by the constituent elements of the compressor control apparatus  100 . For example, the storage unit  160  may store the state data measured by the data detector  120 . The storage unit  160  may store a compressor operation rate based on the first reference value and the coolant temperature. The storage unit  160  may store various programs for controlling overall operations of the compressor control apparatus  100 . 
         [0048]    The storage unit  160  may provide necessary data according to the requests of the compressor  50 , the coolant temperature measurement unit  110 , the data detector  120 , and the controller  150 . The storage unit  160  may be implemented with an integrated memory or divided into a plurality of memories. For example, the storage unit  160  may include read only memory (ROM), random access memory (RAM), and flash memory. 
         [0049]    Hereafter, a compressor control method for a vehicle according to an exemplary embodiment of the present invention will be described with reference to  FIGS. 2 to 4 . 
         [0050]      FIG. 2  is a flowchart illustrating the compressor control method for a vehicle according to the exemplary embodiment of the present invention,  FIG. 3  is a diagram illustrating a first control map according to the exemplary embodiment of the present invention, and  FIG. 4  is a diagram illustrating a second control map according to the exemplary embodiment of the present invention. 
         [0051]    Referring to  FIG. 2 , the controller  150  operates the vehicle when the driver turns on the ignition (S 200 ). The controller  150  may receive a signal from an ignition detector (not illustrated), and check whether the ignition is turned on. When the ignition is turned on, the controller  150  may operate the vehicle according to the request of the driver. 
         [0052]    The controller  150  checks whether the air conditioner is turned on (S 210 ). That is, the controller  150  checks whether the air conditioner is turned on through an air conditioner switch. The air conditioner switch may be turned on by the driver. 
         [0053]    When the air conditioner is in an off state, the controller  150  returns to step S 210  to monitor whether the air conditioner is turned on. 
         [0054]    The controller  150  determines whether the state data satisfy the worst stress condition (S 220  to S 240 ). Specifically, the controller  150  may determine whether the engine and the air conditioner are operated in a heavy load state. Steps S 220  to S 240  may be performed at the same time or in any order. 
         [0055]    The controller  150  determines whether the outdoor temperature is equal to or more than a preset temperature, when the air conditioner is turned on (S 220 ). The controller  150  receives an outdoor temperature from the outdoor temperature sensor  133 , and checks whether the received outdoor temperature is equal to or more than the preset temperature. The preset temperature may indicate a reference temperature which is used to check whether the temperature falls within the worst stress condition. The preset temperature may be set by a pre-specified algorithm (for example, program and probability model) or set by an operator. The preset temperature may be set to 20° C., for example. 
         [0056]    When the outdoor temperature is equal to or more than the preset temperature, the controller  150  determines whether the air volume level of the air conditioner is equal to or more than a preset level (S 230 ). When the outdoor temperature is equal to or more than the preset temperature, the controller  150  checks the air volume level of the air conditioner measured by the air volume sensor  137 , and determines whether the air volume level of the air conditioner is equal to or higher than the preset level. The preset level may indicate the reference air volume level of the air conditioner, which is used to check whether an air volume level falls within the worst stress condition, and include a manually set level and an automatically set level. The manually set level may indicate an air volume level which is manually set by a driver through an apparatus for adjusting the air volume level of the air conditioner. The automatically set level may indicate a preset level which is used when the air volume level of the air conditioner is automatically set by an indoor temperature and an outdoor temperature. That is, the manually set level may indicate a level which is set through manual temperature control (MTC), and the automatically set level may indicate a level which is set through full automatic temperature control (FATC). The manually set level and the automatically set level may be different from each other. For example, the manually set level may be set to a third level, and the automatically set level may be set to a fifth level. 
         [0057]    The controller  150  determines whether the position value of the accelerator pedal is equal to or more than a preset position value, when the air volume level of the air conditioner is equal to or more than the preset level (S 240 ). When the air volume level of the air conditioner is equal to or more than the preset level, the controller  150  checks the position value of the accelerator pedal, received from the APS  135 , and determines whether the position value of the accelerator pedal is equal to or more than the preset position value. As provided herein, the preset position value indicates the position value of the accelerator pedal, which is used as a reference value for checking whether a position value falls within the worst stress condition. The preset position value may be set through a pre-specified algorithm (for example, program and probability model) or set by an operator. The preset position value may be set to 30%, for example. 
         [0058]    When the position value of the accelerator pedal is equal to or more than the preset position value, the controller  150  checks whether the coolant temperature is equal to or higher than the first reference value (S 250 ). When the position value of the accelerator pedal is equal to or more than the preset position value, the controller  150  checks the coolant temperature measured by the coolant temperature measurement unit  110 , and checks whether the coolant temperature is equal to or more than the first reference value. The first reference value may indicate a value which is set to check whether the engine and the air conditioner are operated in a heavy load state. For example, the first reference value may be set to 108° C. 
         [0059]    When the coolant temperature is equal to or more than the first reference value, the controller  150  controls the operation of the compressor  50  by lowering the compressor operation rate (S 260 ). As illustrated in  FIG. 3 , the controller  150  checks a compressor operation rate matched with the coolant temperature, in the first control map  300 . The first control map may include operation rates of the compressor  50  which are set according to coolant temperatures. The first control map may include operation rates for coolant temperatures, which are set in the range of the first reference value  310  to a first predetermined value  320 . The first predetermined value may indicate a coolant temperature for minimizing the operation rate of the compressor  50  when the engine and the air conditioner are operated in a heavy load state. The first predetermined value  320  may be set to 113° C. That is, the first control map  410  may indicate the operation rate of the compressor  50 , which starts to be applied when the coolant temperature is equal to or more than 108° C. and is minimized when the coolant temperature is 113° C. 
         [0060]    When the state data do not satisfy the worst stress condition, the controller  150  determines whether the coolant temperature is equal to or higher than a second reference value (S 270 ). In other words, when the outdoor temperature is less than the preset temperature, the air volume level of the air conditioner is less than the preset level, or the position value of the accelerator pedal is less than the preset position value, the controller  150  determines whether the coolant temperature is equal to or more than the second reference value. The second reference value may be larger than the first reference value. 
         [0061]    When the coolant temperature is equal to or more than the second reference value, the controller  150  controls the operation of the compressor  50  by lowering the compressor operation rate (S 280 ). As illustrated in  FIG. 4 , the controller  150  checks the compressor operation rate matched with the coolant temperature in the second control map  400 . The second control map may include operation rates of the compressor  50 , which are set according to coolant temperatures. The second control map may include operation rates for coolant temperature, which are set in the range of the second reference value  410  to a second predetermined value  420 . The second predetermined value may indicate a coolant temperature for controlling the operation rate of the compressor  50  to the minimum operation rate in a general operation mode of the vehicle. The second reference value  410  may be set to 110° C., and the second predetermined value may be set to 115° C. That is, the second control map  400  may indicate the operation rate of the compressor  50 , which starts to be applied when the coolant temperature is equal to or more than 110° C., and is minimized when the coolant temperature is 115° C. 
         [0062]    When the coolant temperature is less than the first reference value at step S 250  or less than the second reference value at step S 270 , the controller  150  may not lower the compressor operation rate, but control the operation of the compressor  50  to 100% (S 290 ). 
         [0063]    As described above, the compressor control apparatus  100  according to the exemplary embodiment of the present invention may determine whether the engine and air conditioner are in a heavy load state, based on the outdoor temperature, the air volume level of the air conditioner and the position value of the accelerator pedal. When the engine and air conditioner are in a heavy load state according to the outdoor temperature, the air volume level of the air conditioner and the position value of the accelerator pedal, the compressor control apparatus  100  may not turn off the compressor  50  as in the related art, but control the compressor  50  by lowering the compressor operation rate. Therefore, since the operation of the air conditioner is not stopped, the deterioration in durability of the engine and the compressor  50  can be prevented, and the occurrence of moisture on the windows can be prevented. 
         [0064]    While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.