Hybrid compressor with bearing clutch assembly

[0001] The present invention relates to a hybrid refrigerant compressor mainly used for motor vehicle air-conditioning systems.

[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'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'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.

[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.

[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] FIG. 1 is a cross-sectional view showing a hybrid compressor according to one embodiment of the present invention;

[0009] FIG. 2 is a cross-sectional view taken on line 2-2 of FIG. 1 and showing the bearing clutch; and

[0010] FIG. 3 is a block diagram illustrating the compressor, the motor, and the vehicle engine.

[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 16A and 16B. The end 16A 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 16B.

[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.