Abstract:
A hybrid compressor having a driveshaft driven by a plurality of drive sources for a vehicle air-conditioning system. More specifically, the drive sources are the vehicle engine coupled to the compressor via a belt driven clutch and an electric motor driving the compressor. A bearing clutch couples the electric motor to the driveshaft.

Description:
TECHNICAL FIELD OF THE INVENTION  
         [0001]    The present invention relates to a hybrid refrigerant compressor mainly used for motor vehicle air-conditioning systems.  
         BACKGROUND OF THE INVENTION  
         [0002]    The present invention pertains to a hybrid refrigerant compressor having a driveshaft driven by a plurality of drive sources. The drive sources include a belt driven pulley powered by the vehicle&#39;s prime mover engine and an electric motor that can drive the air-conditioning system compressor when the vehicle engine is not operating.  
           [0003]    Generally, a vehicle air-conditioning system includes a refrigeration circuit which includes a compressor and an external circuit connected to the compressor. When the compressor is driven by the engine, refrigerant circulates in the refrigeration circuit and cools the passenger compartment. Typically, the compressor is connected to a single drive source; namely, the vehicle&#39;s engine, driving a belt wrapped on a pulley with an electromagnetic clutch. When the cooling capacity of the refrigeration circuit becomes excessive as the thermal load on the refrigerator circuit decreases, the electromagnetic clutch is de-energized and the operation of the compressor is temporarily stopped. When the engine has stopped, the compressor is not operated and the cooling function is stopped whether the electromagnetic clutch is turned on or off. When the engine is stopped, the compressor can be driven by the motor to cool the passenger compartment. This is a particular problem in so-called hybrid vehicles, in which the prime mover engine may generate electricity to drive electric motors with energy from storage batteries. These vehicles may have operating modes in which cooling is required when the engine is not operated.  
           [0004]    Current hybrid compressors use a common shaft through the compressor either driven from the front by the belt driven pulley or the rear by an electric motor. Upon engagement, the electromechanical clutch attached to the front of the compressor must overcome the momentum of not only the compressor but also the momentum of the rotor of the electric motor. This puts high loads on the compressor drive shaft and the clutch, and causes an engine rpm drop. The compressor controls must also manage the transient electricity produced by the drive motor while the compressor is being driven by the belt driven pulley.  
         BRIEF SUMMARY OF THE INVENTION  
         [0005]    In this invention a bearing clutch assembly interacts with the rotor of the electric motor that allows the motor to drive the driveshaft or let it freewheel. By doing this, the rotor is supported on the bearing assembly during the belt driven pulley operation and the momentum of the rotor is not seen by the clutch being driven from the engine. When the compressor is powered from the electric motor, the bearing clutch is engaged, enabling the compressor to be turned via the electric motor.  
           [0006]    Other aspects and advantages of the invention will become apparent from the following description taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    The feature of the present invention that are believed to be novel are set forth with particularity in the appended claims. The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:  
         [0008]    [0008]FIG. 1 is a cross-sectional view showing a hybrid compressor according to one embodiment of the present invention;  
         [0009]    [0009]FIG. 2 is a cross-sectional view taken on line  2 - 2  of FIG. 1 and showing the bearing clutch; and  
         [0010]    [0010]FIG. 3 is a block diagram illustrating the compressor, the motor, and the vehicle engine. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0011]    The foregoing discussion discloses and describes a preferred embodiment of the invention. One skilled in the art will readily recognize from such discussion and from the accompanying drawings and claims that changes and modifications can be made to the invention without departing from the true spirit and fair scope of the invention as defined in the following claims. The invention has been described in an illustrative manner and it is to be understood that the terminology that has been used is intended to be in the nature of words of description rather than of limitation.  
         [0012]    A hybrid compressor according to one embodiment of the present invention will now be described with reference to FIGS. 1 through 3, inclusive. FIGS. 1 and 3 show the hybrid compressor  10 , and the pulley and electromagnetic clutch  12  and electric motor  14 . The clutch  12  is attached to the front of the compressor  10 . The electric motor  14  is attached to the rear of the compression  10 . The clutch  12  is attached to one end of a driveshaft  16  and selectively transmits power of a vehicle engine  18  to the driveshaft  16 . The electric motor  14  is powered by DC power source which is a battery  20  and is positioned at the opposite end of driveshaft  16  as clutch  12 . A drive circuit  21  controls the supply of electric power from the battery  20  to the clutch  12  in accordance with instructions from a controller  24 . An electric current sensor (not known) detects the value of the electric power supplied to the motor.  
         [0013]    The electric motor  14  is shown in FIG. 1 along with a motor housing  41  joined to the rear of the housing  42  for the compressor  10 . The rear end of the driveshaft  16  passes through the rear housing of the compressor  10 , and terminates in the motor housing  41 . The part of the driveshaft  16  located in the motor housing  41  includes sections  16 A and  16 B. The end  16 A of the output shaft is supported by a radial bearing  26 . A rotor  30  of electric motor  14  is mounted to driveshaft  16  by a bearing clutch  32  at the driveshaft section  16 B.  
         [0014]    The bearing clutch  32  is shown in detail in FIG. 2 as having a plurality of angularly spaced inclined notches  33  formed by stator  30 , acting as an outer race in which are positioned rollers  34 . An inner race  36  is coupled to driveshaft  16 . When the driveshaft  16  turns clockwise, the rollers  34  will be wedged in the notches  33  so the rollers  34  rolls with the shaft  16 . Thus, with respect to the orientation in FIG. 2 when the driveshaft  16  is being driven clockwise, the rollers  34  will roll freely in the notches  33  and torque will not be transmitted to rotor  30 . As a result, when the engine  18  is driving the driveshaft  16 , the rotor  30  will remain at rest (or rotate slowly). Conversely, during when the engine  18  is not driving the shaft  16 , the electric motor  14  is utilized to operate the compressor  10  causing the driveshafts  16  to be driven counter-clockwise, causing rollers  34  to wedge along ramps  35 . In that operating condition, rollers  34  ride along ramp surfaces  35  and the rotor  30  becomes locked to the shaft  16  and they rotate together.  
         [0015]    Attachment of the rotor  30  to the compressor shaft  16  through the bearing clutch assembly  32  enables the rotor  30  to slip with respect to the shaft through bearing clutch assembly  32  that occurs during operation of the internal combustion engine  18  and momentum of the rotor  30  is not seen by the clutch being driven from the engine  18 . When the compressor  10  is powered from the electric motor  14 , the bearing clutch  32  is engaged to the compressor shaft  16  by the nature of the rotor  30  turning and the compressor is then turned via the electric motor  14 .  
         [0016]    It should be recognized that the design of bearing clutch assembly  32  is only one of many known one-way bearing clutch designs. Other designs could be implemented so long as driveshaft  16  can freely rotate with respect to rotor  30  in one rotational direction, and they become engaged to rotate together in the other direction. Also, the functions of supporting driveshaft  16  for rotating could be provided by a separate bearing, and the clutching function served by a separate clutch device.  
         [0017]    The foregoing discussion discloses and describes two preferred embodiments of the invention. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims, that changes and modifications can be made to the invention without departing from the true spirit and fair scope of the invention as defined in the following claims. The invention has been described in an illustrative manner, and it is to be understood that the terminology that has been used is intended to be in the nature of words of description rather than of limitation.