Abstract:
A method for driving a hybrid compressor of an air conditioning system of a vehicle is provided. The vehicle includes a first drive source, and the air conditioning system includes an evaporator. Moreover, the hybrid compressor includes a second drive source, and the hybrid compressor is driven by the first drive source via an electromagnetic clutch or the second drive source, or combination thereof. The method includes the steps of engaging the electromagnetic clutch, detecting a temperature of air dispensed from the evaporator, and disengaging the electromagnetic clutch when the temperature of the air is equal to a predetermined temperature. The method also includes the step of activating the second drive source. Specifically the step of disengaging the electromagnetic clutch when the temperature of the air is equal to the predetermined temperature and the step of activating the second drive source is performed simultaneously or substantially simultaneously.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates generally to air conditioning systems for use in a vehicles, vehicles comprising such air conditioning systems, and methods for driving a hybrid compressor of the air conditioning system. In particular, the present invention is directed towards vehicles, air conditioning systems, and methods for driving hybrid compressors, in which fluctuations in a driving torque of the vehicle is reduced.  
           [0003]    2. Description of Related Art  
           [0004]    Known hybrid vehicles include an engine, and an air conditioning system. The air conditioning system includes a hybrid compressor, and the hybrid compressor includes an electric motor. The hybrid compressor may be driven by the engine or the electric motor, or both.  
           [0005]    A Known hybrid, variable displacement-type compressor, such as the hybrid, variable displacement-type compressor described in U.S. Pat. No. 6,247,899 B1, includes a drive shaft, a compression mechanism, and an electromagnetic clutch. The compression mechanism includes a swash plate. The electromagnetic clutch is coupled operationally to the engine, and the drive shaft is coupled operationally to the electromagnetic clutch and the electric motor. The drive shaft also is coupled operationally to the compression mechanism. Moreover, a driving force is selectively transmitted from the engine to the drive shaft via the electromagnetic clutch, and from the electric motor to the drive shaft.  
           [0006]    A known hybrid, rotary-type compressor, such as the hybrid, rotary-type compressor described in U.S. Pat. No. 6,375,436 B1, includes a drive shaft a compression mechanism, and an electromagnetic clutch. The electromagnetic clutch is coupled operationally to the engine, and the drive shaft is coupled operationally to the electromagnetic clutch and the electric motor. The drive shaft also is coupled operationally to the compression mechanism. Moreover, a driving force is selectively transmitted from the engine to the drive shaft via the electromagnetic clutch, and from the electric motor to the drive shaft.  
           [0007]    Other known hybrid compressors, such as the hybrid compressors described in Japanese Patent Application Nos. 2001.280630 and 2002-031644, include a first drive shaft, a second drive shaft, a first compression mechanism, a second compression mechanism, and an electromagnetic clutch. The electromagnetic clutch is coupled operationally to the engine, and the first drive shaft is coupled operationally to the electromagnetic clutch. The first drive shaft also is coupled operationally to the first compression mechanism. Similarly, the second drive shaft is coupled operationally to the electric motor and the second compression mechanism. Moreover, a driving force is transmitted from the engine to the first drive shaft via the electromagnetic clutch, or from the electric motor to the second drive shaft, or both. As such, the first drive shaft and the second drive shaft may be driven selectively, i.e., by the engine or the electric motor but not both, or simultaneously, i.e. by both the engine and the electric motor.  
           [0008]    In air conditioning systems including such known hybrid compressors, when operation of the air conditioning system begins, a temperature of air dispensed from an evaporator of the compressor is greater than a first temperature. Subsequently, when the temperature of the air dispensed from the evaporator decreases to the first temperature he electromagnetic clutch is disengaged, such that the engine and the compressor transitions from active to inactive to prevent the evaporator from freezing. When the engine is active, the driving force of the engine is transmitted to the drive shaft to drive the compressor, and when the engine is inactive, the driving force of the engine is not transmitted to the drive shaft. Similarly, when the compressor is active, the compressor is driven to compress a refrigerant, and when the compressor is inactive, the compressor does not compress the refrigerant. Subsequently, when the temperature of the air dispensed from the evaporator increases from the first temperature to a second temperature, the electromagnetic clutch is engaged, such that the driving force from the engine is transmitted to the drive shaft, and the compressor transitions from inactive to active. When the compressor transitions from inactive to active, a load demanded by the compressor increases, which causes a driving torque of the vehicle to increase. Moreover, when the compressor frequently transitions from active to inactive and then from inactive to active, the driving torque fluctuates, which decreases the vehicle&#39;s efficiency.  
         SUMMARY OF THE INVENTION  
         [0009]    Therefore, a need has arisen for hybrid compressors which overcome these and other shortcomings of the related art A technical advantage of the present invention is that the driving torque of the vehicle fluctuates less frequently than in the known compressors.  
           [0010]    According to an embodiment of the present invention, an air conditioning system for a vehicle comprises a hybrid compressor and an evaporator, and the vehicle comprises a first drive source. The hybrid compressor comprises a second drive source and a temperature sensor for detecting the temperature of air dispensed from the evaporator. The hybrid compressor is driven by the first drive source via an electromagnetic clutch or the second drive source, or a combination thereof. The electromagnetic clutch is disengaged and the second drive source is active when a temperature of the air dispensed from the evaporator is equal to a first predetermined temperature.  
           [0011]    According to another embodiment of the present invention, a vehicle comprises a fist drive source and an air conditioning system. The air conditioning system comprises a hybrid compressor and an evaporator. The hybrid compressor comprises a second drive source and a temperature sensor for detecting the temperature of air dispensed from the evaporator. The hybrid compressor is driven by the first drive source via an electromagnetic clutch or the second drive source, or a combination thereof. The electromagnetic clutch is disengaged and the second drive source is active when a temperature of air dispensed from the evaporator is equal to a first predetermined temperature.  
           [0012]    According to yet another embodiment of the present invention, a method for driving a hybrid compressor of an air conditioning system of a vehicle is provided. The vehicle comprises a first drive source, and the air conditioning system comprises an evaporator. Moreover, the hybrid compressor comprises a second drive source, and the hybrid compressor is driven by the first drive source via an electromagnetic clutch or the second drive source, or combination thereof. The method comprises the steps of engaging the electromagnetic clutch, detecting a temperature of air dispensed from the evaporator, and disengaging the electromagnetic clutch when the temperature of the air is equal to a predetermined temperature. The method also comprises the step of activating the second drive source. Specifically, the step of disengaging the electromagnetic clutch when the temperature of the air is equal to the first predetermined temperature, and the step of activating the second drive source, are performed simultaneously or substantially simultaneously.  
           [0013]    Other objects, features, and advantages will be apparent to persons of ordinary skill in the art from the following detailed description of the invention and the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    For a more complete understanding of the present invention, the needs satisfied thereby, and the objects, features, and advantages thereof, reference now is made to the following description taken in connection with the accompanying drawing.  
         [0015]    [0015]FIG. 1 is a schematic diagram of an air conditioning system for a vehicle, according to an embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0016]    Preferred embodiments of the present invention and their features and advantages may be understood by referring to FIG. 1.  
         [0017]    Referring to FIG. 1, an air conditioning system  100  for a vehicle (not shown) according to an embodiment of the present invention is depicted. Air conditioning system  100  may comprise a hybrid compressor  4  and a refrigeration system  1 . Hybrid compressor  4  may be a variable displacement-type compressor, a swash plate-type compressor, a rotary-type compressor, a scroll-type compressor, or the like. In an embodiment, the vehicle may comprise a first drive source  2 , e.g., an engine, and hybrid compressor  4  may comprise a second drive source  5 , e.g. an electric motor. In this embodiment, hybrid compressor  4  may be driven by first drive source  2 , second drive source  5 , or both. The driving force of first drive source  2  may be transmitted to hybrid compressor  4  via an electromagnetic clutch  3  attached to hybrid compressor  4 .  
         [0018]    In another embodiment, hybrid compressor  4  may be similar to a hybrid compressor described in U.S. Pat. No. 6,247,899 B1 or U.S. Pat. No. 6,375,436 B1, the disclosures of which are incorporated herein by reference. For example, hybrid compressor  4  may comprise a first compression mechanism (not shown) and a second compression mechanism (not shown). Specifically, first drive source  2  may drive the first compression mechanism, and second drive source  5  may drive the second compression mechanism. Moreover, air conditioning system  100  may comprise means for selecting whether first drive source  2  or second drive source  5 , or both, drives compressor  4 . For example, the means for selecting may comprise a control device  15 , and first drive source  2  and second drive source  5  may operate selectively or simultaneously in response to electrical, mechanical, or electromechanical signals from control device  15 . The vehicle also may comprise an electromagnetic clutch  3  for transmitting a rotational force from firs drive source  2  to a drive shaft (not shown) of compressor  4 . In this embodiment, the drive shaft may comprise a first portion and a second portion. Specifically, first drive source  2  may drive the first portion of the drive shaft via electromagnetic clutch  3 , and second drive source  5  may drive the second portion of the drive shaft in response to the control signals from control device  15 .  
         [0019]    In still another embodiment, hybrid compressor  4  may be similar to a hybrid compressor described in Japanese Patent Application No. 2001-280630 or Japanese Patent Application No. 2002-031664. For example, hybrid compressor  4  may comprise a first drive shaft and a second drive shaft. Moreover, first drive source  2  may drive the first drive shaft via electromagnetic clutch  3 , and second drive source  5  may drive the second drive shaft via control device  15 . In another example, air conditioning system  100  may comprise a pair of hybrid compressors  4 . Specifically, a first hybrid compressor of the pair of hybrid compressors  4  may comprise the first drive shaft, and a second hybrid compressor of the pair of hybrid compressors  4  may comprise the second drive shaft. Moreover, first drive source  2  may drive the first drive shaft via electromagnetic clutch  3 , and second drive source  5  may drive the second drive shaft via control device  15 .  
         [0020]    In any of the above-described embodiments of the present invention, refrigeration system  1  may comprise a plurality of refrigeration tubes, and a refrigerant may be circulated within refrigerant system  1  via the refrigeration tubes. Refrigeration system  1  may comprise compressor  4 , a condenser  6 ; a receiver  7 ; an expansion valve  8 ; and an evaporator  9 . Compressor  4  may be coupled to condenser  6 , and condenser  6  may be coupled to receiver  7 . Receiver  7  may be coupled to expansion valve  8 , and expansion valve  8  may be coupled to evaporator  9 . Moreover, evaporator  9  may be coupled to compressor  4 , such that compressor  4 , condenser  6 , receiver  7 , expansion valve  8 , and evaporator  9  form a closed, refrigeration circuit. In operation, compressor  4  may receive refrigerant gas from evaporator  9  and also may compress that refrigerant gas. Compressing the refrigerant gas may increase a temperature and a pressure of the refrigerant gas. Compressor  4  may pass the compressed refrigerant gas to condenser  6 . When the compressed refrigerant gas flows through condenser  6 , at least a portion of the refrigerant gas may condense into a liquid refrigerant. Moreover, condenser  6  may pass the condensed refrigerant to receiver  7 , and receiver  7  may divide the condensed refrigerant into a liquid refrigerant portion and a refrigerant gas portion Receiver  7  may pass the liquid refrigerant portion of the refrigerant to expansion valve  8 , which may decrease the pressure of the liquid refrigerant When expansion valve  8  reduces the pressure of the liquid refrigerant, expansion valve  8  may pass the refrigerant to evaporator  9 , and heat exchange the refrigerant with air dispensed by a blower  12 , which may evaporate the liquid refrigerant into the refrigerant gas. The refrigerant gas then may be passed to compressor  4 .  
         [0021]    Air conditioning system  100  also may comprise a heater core  11  positioned at a downstream side of evaporator  9 , and an air mix damper  10  formed between the downstream side of evaporator  9  and an upstream side of heater core  11 I Air mix damper  10  may be driven by a servo-motor (not shown). The movement of air mix damper  10  may control a volume of air passing through heater core  11  via evaporator  9 , which may control the air temperature within the interior of the vehicle. Moreover, blower  12 , evaporator  9 , air mix damper  10 , and heater core  11  may be positioned within an air duct  13 . Air conditioning system  100  also may comprise a first discharge port  21 , a second discharge port  22 , and a third discharge port  23 . Discharge ports  21 - 23  may be positioned at a downstream side of air duct  13 . For example, first discharge port  21  may be formed above third discharge port  23 , and second discharge port  22  may be formed between first discharge port  21  and third discharge port  23 . Moreover, first discharge port  21  may be used during a DEFROST mode, second discharge port  22  may be used during a VENT mode, and third discharge port  23  may be used during a FOOT mode. Such modes may determine the source from which the air entering the interior of the vehicle is drawn, or the direction in which the entering air blows, or both.  
         [0022]    A temperature sensor  14  for measuring a temperature Te of an air dispensed from evaporator  9  may be positioned between evaporator  9  and heater core  11 . Temperature sensor  14  also may be connected operationally to control device  15 , and temperature sensor  14  transmits a signal indicating a value of temperature Te to control device  15 . In an embodiment of the present invention, the vehicle also may comprise an electric power supply (not shown), e.g., a battery, for second drive source  5 . Control device  15  also may receive a plurality of signals  16 , such as a plurality of signals indicating an outside air temperature Tam, a vehicle interior temperature Tr, a heater water temperature Tw, an amount of ambient light Tsun, a voltage Bt of the electric power supply, a vehicle speed Sp, an engine rotational speed Ne, and an accelerator opening degree Acc, or the like. Based on signals  16  and temperature Te of air dispensed from evaporator  9 , control device  15  may generate a first control signal  17  for controlling a rotational speed of second drive source  5 , and a second control signal  18  for controlling the engagement and disengagement of electromagnetic clutch  3 .  
         [0023]    Specifically, when second drive source  5  drives compressor  4 , electromagnetic clutch  3  may be disengaged, and first control signal  17  may be transmitted to second drive source  5  to control the rotational speed of second drive source  5 . Nevertheless, when first drive source  2  drives compressor  4 , first control signal  17  may be deactivated, and electromagnetic clutch  3  may be engaged. In another embodiment of the present invention, first drive source  2  and second drive source  5  may operate simultaneously, Moreover, based on temperature Te of the air dispensed from evaporator  9 , control device  15  may select the rotational speed of second drive source  5 , or determine whether to engage or disengage electromagnetic clutch  3 , or both.  
         [0024]    In any of the above-described embodiments of the present invention, when first drive source  2  drives compressor  4 , and control device  5  detects that air temperature Te equals a first predetermined tempers electromagnetic clutch  3  transitions from engaged to disengaged, and second drive source  5  transitions from inactive to active. For example, the first predetermined temperature may be between about 0° C. and about 3° C. When second drive source  5  is active, second drive source  5  drives compressor  4 , and when second drive source  5  is inactive, second drive source  5  does not drive compressor  4 . Specifically, when operation of air conditioning system  100  begins, air temperature Te may be greater than the first predetermined temperature. Moreover, during the operation of air conditioning system  100 , air temperature Te may decease to the first predetermined temperature, which causes electromagnetic clutch  3  to transition from engaged to disengaged and second drive source  5  to transition from inactive to active. The transition of electromagnetic clutch  3  from engaged to disengaged, and the transition of second drive source  5  from inactive to active, may occur simultaneously or substantially simultaneously. Moreover, the driving torque of the vehicle may be unchanged or substantially unchanged by the transition from first drive source  2  driving compressor  4  to second drive source  5  diving compressor  4 . Specifically, in any of the above described embodiments of compressor  4 , when second drive source  5  drives compressor  4 , a rotational speed of second drive source  5  may be controlled, such that a discharge capacity of compressor  4  is less than when first drive source  2  drives compressor  4 .  
         [0025]    After electromagnetic clutch  3  transitions from engaged to disengaged, and second drive source  5  transitions film inactive to active, air temperature Te increases ten the first predetermined temperature to a second predetermined temperature. For example, the second predetermined temperature may be between about 4° C. and about 6° C. When air temperature Te is about equal to the second predetermined temperature, second drive source  5  transitions from active to inactive, and electromagnetic clutch  3  transitions from disengaged to engaged. Nevertheless, the rate at which air temperature Te increases from the first predetermined temperature to the second predetermined temperature when second drive source  5  drives compressor  4  is less than the rate at which air temperature Te increases from the first predetermined temperature to the second predetermined temperature when compressor  4  transitions from active to inactive after air temperature Te decreases and becomes about equal to the first predetermined temperature. Thus, the amount of time between disengaging and engaging electromagnetic clutch  3  increases relative to the known hybrid compressors. Moreover, compressor  4  may not transition from active to inactive when air temperature Te decreases to the first predetermined temperature during the operation of air conditioning system  100 . Consequently, the driving torque of the vehicle may not fluctuate.  
         [0026]    While the invention has been described in connection with preferred embodiments, it will be understood by those skilled in the art that variations and modifications of the preferred embodiments described above may be made without departing from the scope and spirit of this invention. Other embodiments will be apparent to those skilled in the art from a consideration of the specification or from a practice of the invention disclosed herein. It is intended that the specification and the described examples are considered exemplary only, with the true scope of the invention indicated by the following claims.