Abstract:
The invention relates to a fluid machine, more particularly to a hybrid compressor for a motor vehicle and has an object to reduce vibration and noises thereof.  
     According to a feature of the present invention, a fluid machine comprises a pump mechanism (compressor) for compressing fluid by receiving a driving force at least from an outside driving source (engine) or an electric motor, wherein when the pump mechanism is driven by the outside driving source (engine), a torque in an opposite phase to a component of torque variation generated at the pump mechanism is applied by the electric motor to the pump mechanism. And thereby the component of the torque variation at the pump mechanism can be set off by the torque in the opposite phase generated at the electric motor to reduce the vibration and noises at the pump mechanism and/or accessories, such as an alternators mounted to the engine.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
         [0001]    This application is based on Japanese Patent Application No. 2003-160951 filed on Jun. 5, 2003, the disclosures of which is incorporated herein by reference.  
         FIELD OF THE INVENTION  
         [0002]    The present invention relates to a fluid machine having a pump mechanism (compressor) for compressing working fluid (refrigerant) and driven by at least an outside driving source or an electric motor, in particular to a fluid machine to be used for a hybrid vehicle which runs by a combination of driving forces from an electric motor and an internal combustion engine.  
         BACKGROUND OF THE INVENTION  
         [0003]    In a conventional stationary air-conditioner, for example an air-conditioner for home use, a compressor is driven by an electric motor. The electric motor is operated at least two different control modes, one of which is an operational control mode when a rotational speed of the electric motor is low and the other of which is an operational control mode when the rotational speed of the electric motor is high, so that vibration of the compressor is decreased in a low speed operation thereof.  
           [0004]    The hybrid vehicle already in the market has an electric motor and an internal combustion engine for running the vehicle, wherein the vehicle runs by a driving force from the electric motor alone, by a driving force from the engine alone, or by a combination of those driving forces. A compressor of an air-conditioner for the hybrid vehicle is, accordingly, driven by a driving force from the engine or driven by an electric motor provided for exclusively driving the compressor.  
           [0005]    Since the compressor sucks and compresses the working fluid (refrigerant), anti-torque at the compressor varies so that the anti-torque at a suction stroke is smaller than that at a compression stroke.  
           [0006]    When the compressor is driven by the driving force from the engine via a power transmitting means, such as V-belts, the variation of the anti-torque generated at the compressor will be transmitted to the engine through the V-belts. As a result, accessories mounted to the engine, such as an alternator, may be resonated to generate a larger vibration and noise, i.e. resonance of accessories.  
         SUMMARY OF THE INVENTION  
         [0007]    It is, therefore, an object of the present invention, in view of the above mentioned problems, to provide a new fluid machine which is capable to suppress vibration and noises thereof.  
           [0008]    According to a feature of the present invention, a fluid machine comprises a pump mechanism (compressor) for compressing a working fluid by receiving a driving force at least from an outside driving source (engine) or an electric motor, wherein when the pump mechanism is driven by the outside source of driving force (engine), a torque in an opposite phase to a component of torque variation generated at the pump mechanism is applied by the electric motor to the pump mechanism. And thereby the component of the torque variation at the pump mechanism can be set off by the torque in the opposite phase generated at the electric motor to reduce the vibration and noises at the pump mechanism and/or accessories, such as an alternator, mounted to the engine.  
           [0009]    According to another feature of the present invention, the electric motor, the pump mechanism (compressor) and a power transmitting device for transmitting the driving force from the outside driving source (engine) to the pump mechanism are integrally assembled as a one unit.  
           [0010]    According to a further feature of the present invention, when the pump mechanism (compressor) is driven by the outside driving source (engine) and when a frequency of the vibration of the pump mechanism reaches a predetermined frequency range (for resonance frequency range), the supply of the electric power to an electromagnetic clutch (the power transmitting device) is cut off and the operation of the pump mechanism will be continued by the driving force from the electric motor.  
           [0011]    As a result, the vibration of the pump mechanism is prevented from being transmitted to the outside driving source, and thereby the resonance of accessories can be prevented.  
           [0012]    According to a further feature of the present invention, when the pump mechanism (compressor) is driven by the outside driving source (engine) and when a rotational speed of the pump mechanism reaches a predetermined speed range (for resonance speed range), the supply of the electric power to the electromagnetic clutch (the power transmitting device) is cut off and the operation of the pump mechanism will be continued by the driving force from the electric motor.  
           [0013]    As a result, the same effect can be obtained, namely the vibration of the pump mechanism is prevented from being transmitted to the outside driving source, and thereby the resonance of accessories can be prevented.  
           [0014]    According to a further feature of the present invention, the electric motor, the power transmitting device (the electromagnetic clutch) and the pump mechanism (compressor) are operatively connected with each other by a single rotating shaft. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings:  
         [0016]    [0016]FIG. 1 is a schematic diagram showing a control system for vehicle accessories according to the present invention;  
         [0017]    [0017]FIG. 2 is a cross-sectional view showing an electrically driven compressor according to a first embodiment of the present invention;  
         [0018]    [0018]FIG. 3 is a graph showing a relationship between a torque and a rotational angle of a shaft;  
         [0019]    [0019]FIG. 4 is a graph showing a relationship between maximum displacement of vibrations for an alternator and a rotational speed of a shaft;  
         [0020]    [0020]FIG. 5 is a cross-sectional view showing an electrically driven compressor according to a second embodiment of the present invention;  
         [0021]    [0021]FIG. 6 is a graph showing an operation of a power transmitting device for the second embodiment; and  
         [0022]    [0022]FIG. 7 is a graph showing a relationship between a torque and a rotational angle of a shaft. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]    (First Embodiment)  
         [0024]    A first embodiment of the present invention will now be explained with reference to FIGS. 1 and 2, wherein FIG. 1 shows a schematic diagram of a control system for vehicle accessories, and FIG. 2 shows a cross-sectional view of an electrically driven compressor according to a first embodiment of the present invention  
         [0025]    In FIG. 1, a numeral  1  designates an internal combustion engine (an outside driving source) generating a driving force for vehicle running, a numeral  2  designates an alternator (an engine accessory) driven by the driving force from the engine to generate electric power which will be charged into a battery  8 .  
         [0026]    In the alternator  2 , as is well known, a field current to be supplied to a rotor is controlled by a voltage regulator  7  to control strength of rotating magnetic field, and thereby to control electric power to be generated.  
         [0027]    A numeral  11  designates a compressor which is driven by at least one of the driving force from the engine  1  and a driving force of an electric rotating machine (electric motor)  12 , wherein the compressor  11  sucks and compresses working fluid (refrigerant of a refrigerating cycle). In the present embodiment shown in FIG.  2 , a numeral  10  designates a hybrid compressor (fluid machine), which is of an all-in-one unit comprising the compressor  11  and the electric motor  12  integrally and operatively connected to the compressor  11 .  
         [0028]    A numeral  3  designates a condenser, which is a heat exchanger for radiating heat from high-pressure high-temperature refrigerant pumped out from the compressor  11 . A numeral  4  designates a pressure reducing device (generally called as an expansion valve) for reducing pressure of the refrigerant cooled down by the condenser  3 . A numeral  5  designates an evaporator for evaporating the refrigerant to perform a refrigeration performance. In this embodiment, the condenser  3  cools down the refrigerant through heat exchange with the ambient air, whereas the evaporator  5  heats the refrigerant through heat exchange with air to be blown out into a passenger compartment of the vehicle.  
         [0029]    A numeral  6  designates a motor control unit for controlling an operation of the electric motor  12  and a signal of an engine rotational speed is input to the motor control unit  6  from a rotational speed sensor  6   a.    
         [0030]    When the compressor  11  is driven by the electric motor  12 , the rotational speed thereof is controlled by the motor control unit  6  by controlling voltage to be applied to the electric motor. And when the electric motor  12  is operated as the electric power generator, the power generation is controlled by the voltage regulator  7 .  
         [0031]    The hybrid compressor  10  will be explained with reference to FIG. 2.  
         [0032]    The hybrid compressor  10  comprises a scroll type compressor  11  for sucking in and compressing the refrigerant, the electric rotating machine  12  (in this embodiment, DC blushless motor) for driving the compressor  11 , and a power transmitting device  13 , such as an electromagnetic clutch, for selectively transmitting the driving force from the engine  1  to the compressor  11 , wherein the compressor  11 ,. the electric motor  12  and the electromagnetic clutch  13  are integrally and operatively connected to each other.  
         [0033]    As explained above, the electric rotating machine (electric motor)  12  is the DC blushless motor in this embodiment, wherein a stator core  12   a  is made of magnetic material such as silicon steel plates and fixed to a motor housing  12   b  by shrink fit or tight fit. A coil  12   c  is wound on the stator core  12   a . The stator core  12   a  and the coil  12   c  constitute a stator.  
         [0034]    A numeral  12   d  designates a rotor having multiple permanent magnets and a shaft  14 , which is rotationally supported by bearings  12   e  and  12   f.    
         [0035]    The bearing  12   f  is fixed to a middle housing  11   a  which is fixed to the motor housing  12   b  by fixing means such as bolts, while the bearing  12   e  is fixed to the motor housing  12   b.    
         [0036]    The scroll type compressor  11  is explained. A shell  11   b  is an element fixed to the middle housing  11   a  to form a space therein and formed with a spiral scroll wrap  11   c  extending towards the middle housing  11   a . The shell  11   b  operates as a fixed scroll.  
         [0037]    A movable scroll  11   f  is operatively disposed in the space between the middle housing  11   a  and the shell (fixed scroll)  11   b  and comprises a base plate  11   e  and a spiral scroll wrap  11   d  protruding from the base plate  11   e  towards the fixed scroll  11   b , wherein wall portions of the spiral scroll wraps  11   c  and lid are contacted with each other to form working chambers V. When the movable scroll  11   f  is rotated, the space of the working chamber V will be expanded or decreased to thereby suck in the working fluid (refrigerant) and compress the refrigerant.  
         [0038]    A cylindrical boss portion  11   g  is formed at an almost center of the base plate  11   e  and a bush  14   b  is rotationally supported by the cylindrical boss portion  11   g  via a needle bearing  14   c . The bush  14   b  is connected to a crank portion  14   a  formed at one end (right-hand end in the drawing) of the shaft  14 .  
         [0039]    The crank portion  14   a  is eccentrically formed to the shaft  14  from a rotational center of the shaft  14 . And therefore, when the shaft  14  is rotated the movable scroll  11   f  is rotated with an orbit motion around the shaft  14 .  
         [0040]    The bush  14   b  is connected to the crank portion  14   a  in such a way that the bush  14   b  will be displaced by a certain small distance in a plain perpendicular to the axis of the shaft  14 , so that the movable scroll  11   f  will be displaced in a direction that contact pressure between the scroll wraps  11   c  and  11   d  will be increased by means of a reaction force for compression.  
         [0041]    A reference numeral  11   h  designates an autorotation preventing mechanism (comprising a pair of pins and a ring) for preventing the autorotation of the movable scroll  11   f  around the crank portion  14   a.    
         [0042]    When the shaft  14  is rotated, the movable scroll  11   f  is rotated with the orbital motion around its orbital axis (which is equal to the rotational center of the shaft  14 ) in a plain perpendicular to the rotational axis of the shaft  14 , while the autorotation of the movable scroll  11   f  around the crank portion  14   a  is prevented.  
         [0043]    A rear housing  11   j  is fixed to the shell  11   b  by bolts or the like to form a discharge chamber  11   k  for equalizing the pressure of the refrigerant by smoothing pulsation of the pumped out refrigerant.  
         [0044]    A numeral  11   m  designates a discharge port formed at almost center of the shell (the fixed scroll)  11   b  to communicate the working chamber V with the discharge chamber  11   k.    
         [0045]    A discharge valve and a valve stopper are fixed to the fixed scroll  11   b  by a bolt at the discharge port, wherein the valve is a check valve of a reed valve type for preventing the pumped out refrigerant from flowing back to the working chamber V from the discharge chamber  11   k , and the stopper is a plate for limiting the movement of the reed valve.  
         [0046]    When the electric motor  12  is operated, the refrigerant is sucked into the compressor  11  through a suction port  11   n . Then refrigerant further flows into a motor chamber  12   h  having the rotor  12   d  and the stator through an inlet port  12   g  formed at the motor housing  12   b , to thereby cool down the electric motor  12 . The refrigerant compressed by the compressor  11  is discharged through the chamber  11   k  and an outlet port lip to the condenser  3 .  
         [0047]    The electromagnetic clutch  13  comprises a pulley  13   a  rotationally supported by the motor housing  12   b  and receiving a driving force from the engine via V-belts, an armature plate  13   c  fixed to the shaft  14 , and an electromagnetic coil  13   d , so that when the coil  13   d  is energized the armature plate  13   c  is attracted to a rotor portion  13   b  of the pulley  13   a  to rotate the shaft  14 .  
         [0048]    As above, the electric motor  12 , the electromagnetic clutch  13  and the compressor  11  are operatively connected to each other by the shaft  14  which transmits the driving force.  
         [0049]    An operation of the hybrid compressor  10  will now be explained.  
         [0050]    [An Operation in Which the Compressor  11  is Driven by the Electric Motor  12 ] 
         [0051]    In this operation, the supply of the electric power to the electromagnetic clutch  13  is cut off to disconnect the compressor  11  from the engine  1  and instead the electric power will be supplied to the coil  12   c  (the stator). The torque to be generated at the electric motor  12  is controlled by the voltage applied to the electric motor and the rotational speed thereof is controlled by the frequency of the electric current supplied to the coil  12   c.    
         [0052]    [An Operation in Which the Compressor  11  is Driven by the Engine  1 ] 
         [0053]    In this operation, the electric power is supplied to the electromagnetic clutch  13  to operatively connect the compressor  10  with the engine  1 , so that the rotational driving force will be transmitted from the engine  1  to the compressor  11 .  
         [0054]    In this operation, as shown by a solid line in FIG. 3, a torque (anti-torque) necessary for driving the compressor varies in conjunction with the suction and compression of the refrigerant by the compressor  11 . The tension at the V-belts is likewise varied in response to the variation of the torque, and then the variation of the torque is transmitted to the engine  1  via the V-belts. As a result, accessories mounted to the engine  1 , such as an alternator, may be resonated to generate a larger vibration and noise, i.e. resonance of accessories.  
         [0055]    According to the embodiment of the present invention, a torque in opposite phase (as indicated by a dotted line in FIG. 3) to the torque for driving the compressor  11  is generated by the electric motor  12  and applied to the compressor  11 , to set off the torque variation generated at the compressor, and as a result the resonance of accessories can be suppressed.  
         [0056]    The torque variation generated at the scroll compressor  11  is determined by geometric configuration thereof, and the frequency of the torque variation is in proportion to the rotational speed of the shaft  14 . Accordingly, the frequency of the torque in the opposite phase is determined by calculating the frequency of the torque variation generated at the scroll compressor  11  based on the calculated rotational speed of the shaft  14 , namely the compressor  11 , from the signal of the rotational speed sensor  6   a.    
         [0057]    (Second Embodiment)  
         [0058]    When the mounting rigidity of the accessories, such as the alternator  2 , to the engine  1  is low, and the torque variation generated at the compressor  11  corresponds to the resonance frequency of the accessories  2 , the resonance of accessories becomes larger, as shown in FIG. 4.  
         [0059]    According to the second embodiment, in the case that the compressor  11  is driven by the engine  1 , the torque in the opposite phase is likewise generated by the electric motor  12  and applied to the compressor  11 , as in the same manner in the first embodiment. In addition, when the frequency of the torque variation generated at the compressor  11  comes closer to the resonance frequency of the accessories, the supply of the electric power to the electromagnetic clutch  13  is cut off to disconnect the compressor  11  from the engine  1  and the compressor is driven by the electric motor  12 . As a result of the operation, the resonance of accessories can be surely suppressed.  
         [0060]    As explained above, since the frequency of the torque variation generated at the compressor  11  varies in proportion to the rotational speed of the compressor  11 , it is determined that the frequency of the torque variation at the compressor  11  reaches an area of the resonance frequency when the rotational speed of the compressor  11  becomes within a predetermined speed range, which is decided in advance according to tests and so on.  
         [0061]    When the frequency of the torque variation generated at the compressor  11  goes out of the area of the resonance frequency, the electric power will be again supplied to the electromagnetic clutch  13  to transmit the driving force from the engine  1  to the compressor  11 , while the torque in the opposite phase is generated at the electric motor  12  and applied to the compressor  11 .  
         [0062]    (Third Embodiment)  
         [0063]    In this embodiment, a variable speed gearing  15  is used for the hybrid compressor  10 , as shown in FIG. 5. The variable speed gearing  15  comprises an internal gear (ring gear)  15   a  of a ring form, multiple (for example, three) planetary gears  15   b  engaged with the internal gear  15   a  and a sun gear  15   c  engaged with the planetary gears  15   b.    
         [0064]    The sun gear  15   c  is integrally formed with the rotor  12   d  of the electric motor  12 , the planetary gears  15   b  are integrally formed to the shaft  13   d  which rotates with the armature plate  13   c  of the electromagnetic clutch  13  as one unit, and the ring gear  15   a  is integrally formed with the shaft  14 .  
         [0065]    A bearing  13   e  rotationally supports the shaft  13   d , a bearing  13   f  rotationally supports the sun gear  15   c , namely the rotor  12   d , with respect to the shaft  14 , and a bearing  13   g  rotationally supports the ring gear  15   a  with respect to the shaft  14 .  
         [0066]    An operation of the hybrid compressor  10  according to the third embodiment will be explained.  
         [0067]    [An Operation in Which the Compressor  11  is Driven by the Electric Motor  12 ] 
         [0068]    The electric power is supplied to the electromagnetic clutch  13  to connect the shaft  13   d  with the pulley  13   a  and the electric power is also supplied to the stator coil  12   c.    
         [0069]    In this case, a planetary carrier supporting the planetary gear  15   b  is connected to the pulley  13   a  via the shaft  13   d . As the engine is not running in this case, and thereby the planetary carrier as well as the shaft  13   d  is not rotated, the rotational force of the electric motor  12  will be transmitted to the scroll compressor  11  via the variable speed gearing  15  with the rotational speed being decreased.  
         [0070]    [An Operation in Which the Compressor  11  is Driven by the Engine  1 ] 
         [0071]    The electric power is supplied to the electromagnetic clutch  13  and also to the electric motor  12  to generate such a torque at the rotor  12   d  that the sun gear, namely the rotor  12   d , may not be rotated. As a result, the rotational driving force of the engine  1  transmitted to the electromagnetic clutch  13  will be finally transmitted to the scroll compressor  11  via the variable speed gearing  15  with the rotational speed being increased.  
         [0072]    When the sung gear  15   c  is rotated and the rotational speed is controlled, a change gear ratio can be controlled as shown in FIG. 6. In FIG. 7, a dotted line shows the torque of the electric motor when the change gear ratio is controlled.  
         [0073]    (Other Embodiments)  
         [0074]    In the above embodiments, although the scroll compressor is used as the pumping machine for compressing the refrigerant, it is not limited to this type, but the other types of the compressors, such as rotary type, piston type, vane type and so on can be used.  
         [0075]    Although the above embodiments are explained as the fluid machine to be used to the hybrid compressor for a motor vehicle, however, the present invention can be used for any other fluid machines.  
         [0076]    The DC brushless motor is explained as the electric motor  12  in the above embodiments. It is, of course, possible to use any other types of the electric motors can be used for the purpose of the present invention.  
         [0077]    In the above embodiments, the electric motor  12 , the electromagnetic clutch  13  and the scroll compressor  11  are operatively connected with each other by the shaft  14  which transmits the driving force to the compressor  11 . It is, however, not necessary to limit the present invention to this structure.