Patent Publication Number: US-2004055843-A1

Title: Power generation and actuating system

Description:
TECHNICAL FIELD  
       [0001] The present invention relates to a generator and motor system. More specifically, according to the system, when an engine of a vehicle is running, power transmission from the engine drives a motor generator, which in turn generates power, and a compressor of an air-conditioner. When the engine is stopped, the motor generator is put in motion by power supply from the outside to drive the compressor.  
       BACKGROUND ART  
       [0002] Japanese Laid-Open Utility Model Publication No. 6-87678 discloses such system. That is, a rotary shaft of a compressor is coupled to a rotary shaft of a motor generator to rotate integrally with each other. An electromagnetic clutch is located in a power transmission path between the rotary shafts and an engine.  
       [0003] When the electromagnetic clutch is turned on, the rotary shafts are connected to the engine. Thus, power is transmitted from the engine to the rotary shafts, which drives the motor generator and the compressor. When the engine is stopped, the electromagnetic clutch is turned off to discontinue power transmission among the motor generator, the compressor, and the engine. At this time, the motor generator is put in motion by power supply from the outside and drives the compressor.  
       [0004] However, in the conventional system, while transmitting power of the engine to the motor generator and the compressor, the electromagnetic clutch is electrically controlled from the outside to be turned on and off such that power of the motor generator is not transmitted to the engine. This not only complicates a controller of the system but also increases the power consumption of the system.  
       DISCLOSURE OF THE INVENTION  
       [0005] Accordingly; it is an objective of the present invention to provide a generator and motor system that simplifies a controller of the system and reduces the power consumption of the system.  
       [0006] To achieve the above objective, the present invention provides a generator and motor system. When an engine is running, a rotational apparatus is driven by power from the engine, and a motor generator is driven to generate power. When the engine is stopped, the motor generator is put in motion by power supply from the outside to drive the rotational apparatus. The generator and motor system includes a mechanical power transmission mechanism for transmitting power of the engine to the motor generator and the rotational apparatus. The power transmission mechanism permits power transmission from the engine to the motor generator and the rotational apparatus, and prevents power transmission from the motor generator to the engine. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0007]FIG. 1 is a cross-sectional view illustrating a generator and motor system according to a first embodiment;  
     [0008] FIGS.  2 ( a ) and  2 ( b ) are enlarged partial cross-sectional views illustrating an operating state of a driven pulley and a one-way clutch;  
     [0009]FIG. 3 is a schematic view illustrating a generator and motor system according to a second embodiment; and  
     [0010]FIG. 4 is a schematic view illustrating a generator and motor system according to a third embodiment. 
    
    
     BST MODE FOR CARRYING OUT THE INVENTION  
     [0011] A generator and motor system according to a first embodiment of the present invention will now be described. The generator and motor system is used in a vehicle.  
     [0012]FIG. 1 shows a generator and motor system. A motor generator MG is operably coupled to a drive source of a vehicle, which is an engine Eg in the first embodiment, via a power transmission mechanism PT. A swash plate type variable displacement compressor (hereinafter, simply referred to as a compressor) CP is operably coupled to the engine Eg via the power transmission mechanism PT and the motor generator MG. The compressor CP is a rotational apparatus, which forms part of a refrigerant circuit of an air-conditioner. The compressor CP is operably coupled to the engine Eg downstream of the motor generator MG in a power transmission path.  
     [0013] The power transmission mechanism PT mechanically permits power transmission from the engine Eg to the motor generator MG and the compressor CP, and prevents power transmission from the motor generator MG to the engine Eg. Therefore, the power transmission mechanism PT can restrict the direction of the power transmission. More specifically, when the engine Eg is running, power transmission from the engine Eg drives the motor generator MG, which generates power, and the compressor CP, which compress refrigerant gas. When the engine Eg is stopped, power transmission among the motor generator MG, the compressor CP, and the engine Eg is. discontinued. Meanwhile, the motor generator MG generates power by external power supply and drives the compressor CP.  
     [0014] As shown in FIG. 1, the motor generator MG includes a front housing member  41  and a rear housing member  42 , which is secured to the rear end of the front housing member  41 . The front housing member  41  and the rear housing member  42  form the housing assembly of the motor generator MG. The left side of FIG. 1 is referred to as the front side and the right side of FIG. 1 is referred to as the rear side.  
     [0015] The front housing member  41  and the rear housing member  42  define an accommodating chamber  43 . A first rotary shaft  44  is rotatably supported inside the accommodating chamber  43 . The first rotary shaft  44  is operably coupled to the engine Eg via the power transmission mechanism PT.  
     [0016] A magnet  45  is secured to the first rotary shaft  44  inside the accommodating chamber  43  and rotates integrally with the first rotary shaft  44 . Stator cores  47 , each of which is wound by a coil  46 , are fixed to the inner circumferential surface of the accommodating chamber  43  to surround the magnet  45 .  
     [0017] A controller  49  of the motor generator MG includes an inverter  49   a . The inverter  49   a  is located on a power supply path between the coils  46  of the motor generator MG and a battery  50 . When the engine Eg is running, the controller  49  controls the motor generator MG to function as a generator. Alternate current generated by the motor generator MG is converted to direct current by the inverter  49   a  and supplied to the battery  50 . When a passenger compartment needs to be cooled while the engine Eg is stopped, direct current drawn from the battery  50  is converted to alternate current by the inverter  49   a  and supplied to the motor generator MG. Thus, the motor generator MG functions as a motor to drive the compressor CP. Therefore, the passenger compartment can be refrigerated although the engine Eg is stopped.  
     [0018] As shown in FIG. 1, the compressor CP includes a cylinder block  1 , a front housing member  2 , which is secured to the front end of the cylinder block  1 , a rear housing member  4 , which is secured to the rear end of the cylinder block  1  with a valve plate assembly  3  located in between. The cylinder block  1 , the front housing member  2 , and the rear housing member  4  form the housing assembly of the compressor CP. The compressor CP is secured to the rear end of the rear housing member  42  of the motor generator MG with the front end of the front housing member  2 .  
     [0019] In the first embodiment, the front housing member  2  of the compressor CP is fastened to the front housing member  41  and the rear housing member  42  of the motor generator MG with a bolt  48 . Therefore, the housing assembly of the compressor CP is easily detachable from the housing assembly of the motor generator MG.  
     [0020] A crank chamber  5  is defined in a region surrounded by the cylinder block  1  and the front housing member  2 . A second rotary shaft  6  is rotatably arranged inside the crank chamber  5 . The front end of the second rotary shaft  6  that projects from the front housing member  2  is directly coupled to the rear end of the first rotary shaft  44  of the motor generator MG along the same axis L by easily detachable means, such as an engagement of a recess and a projection or a bolt.  
     [0021] A lug plate  11  is secured to the second rotary shaft  6  in the crank chamber  5 . The lug plate  11  rotates integrally with the second rotary shaft  6 . A swash plate  12  is accommodated in the crank chamber  5 . The swash plate  12  is slidably and pivotally supported by the second rotary shaft  6 . A hinge mechanism  13  is located between the lug plate  11  and the swash plate  12 . Therefore, the swash plate  12  rotates integrally with the lug plate  11  and the second rotary shaft  6 . The swash plate  12  also slides along the axis L of the second rotary shaft  6  and inclines with respect to the second rotary shaft  6 .  
     [0022] Cylinder bores  1   a  (only one shown) are formed in the cylinder block  1  to surround the second rotary shaft  6 . A single headed piston  20  is accommodated in each cylinder bore  1   a  and reciprocates in the cylinder bore  1   a . The front opening and the rear opening of each cylinder bore  1   a  are closed by the piston  20  and the valve plate assembly  3 . A compression chamber, the volume of which varies in accordance with reciprocation of the piston  20 , is defined in each cylinder bore  1   a . Each piston  20  is coupled to the peripheral portion of the swash plate  12  by a pair of shoes  19 . Therefore, when the swash plate  12  rotates with the second rotary shaft  6 , the shoes  19  convert the rotation of the swash plate  12  into reciprocation of the pistons  20 .  
     [0023] A suction chamber  21  and a discharge chamber  22  are defined between the valve plate assembly  3  and the rear housing member  4 . When each piston  20  moves from the top dead center position to the bottom dead center position, refrigerant gas in the suction chamber  21  is drawn into the corresponding cylinder bore  1   a  via one of suction ports  23  and one of suction valves  24  formed in the valve plate assembly  3 . When each piston  20  moves from the bottom dead center position to the top dead center position, refrigerant gas in the corresponding cylinder bore  1   a  is compressed to a predetermined pressure and is discharged to the discharge chamber  22  via one of discharge ports  25  and one of discharge valves  26  formed in the valve plate assembly  3 .  
     [0024] As shown in FIG. 1, the refrigerant circuit of the air-conditioner includes the compressor CP and an external refrigerant circuit  30 , which connects the discharge chamber  22  and the suction chamber  21  of the compressor CP at the outside the compressor CP. The external refrigerant circuit  30  includes a condenser  31 , a decompression device, and an evaporator  33 . The decompression device is an expansion valve  32  in this embodiment. A shutoff valve  34  is located on a refrigerant passage between the discharge chamber  22  of the compressor CP and the condenser  31  of the external refrigerant circuit. When the pressure in the discharge chamber  22  decreases below a predetermined value, the shutoff valve  34  disconnects the refrigerant passage from the compressor CP and stops circulation of refrigerant through the external refrigerant circuit  30 .  
     [0025] As shown in FIG. 1, in the compressor CP, the inclination angle of the swash plate  12  can be set to an arbitrary angle between the maximum inclination angle (a state shown in FIG. 1) and the minimum inclination angle by adjusting the pressure in the crank chamber  5  using an electromagnetic control valve  29 . The minimum inclination angle is not zero but in the vicinity of zero. The inclination angle of the swash plate  12  refers to the angle of the swash plate  12  with respect to a line that is perpendicular to the axis L of the second rotary shaft  6 .  
     [0026] The crank chamber  5  and the suction chamber  21  are connected to each other by a bleed passage  27 . The discharge chamber  22  and the crank chamber  5  are connected to each other by a supply passage  28 . The electromagnetic control valve  29  is located on the supply passage  28 . The position of a valve body  29   a  of the electromagnetic control valve  29 , or the valve opening degree, is varied in accordance with the amount of power supply to a solenoid  29   b  from the outside. This controls the amount of pressurized discharge gas from the discharge chamber  22  to the crank chamber  5  through the supply passage  28 . The pressure in the crank chamber  5  is determined in accordance with the relationship between the amount of refrigerant gas introduced to the crank chamber  5  and the amount of refrigerant gas sent out from the crank chamber  5  to the suction chamber  21  via the bleed passage  27 . The difference between the pressure in the crank chamber  5  and the pressure in the cylinder bores  1   a  is changed in accordance with the change in the pressure in the crank chamber  5 , which varies the inclination angle of the swash plate  12 . As a result, the stroke of the pistons  20 , that is, the displacement of the compressor CP is controlled.  
     [0027] For example, if the opening degree of the displacement control valve  29  is decreased, the pressure in the crank chamber  5  decreases, which decreases the difference between the pressure in the crank chamber  5  and the pressure in the cylinder bores  1   a . Accordingly, the swash plate  12  is tilted to increase the inclination angle, which increases the displacement of the compressor CP. In contrast, when the opening degree of the displacement control valve  29  increases, the pressure in the crank chamber  5  increases, which increases the difference between the pressure in the crank chamber  5  and the pressure in the cylinder bores  1   a . Accordingly, the swash plate  12  is tilted to decrease the inclination angle, which decreases the displacement of the compressor CP.  
     [0028] The opening degree of the displacement control valve  29  is controlled by a displacement control apparatus  36  based on information sent from an external information detection apparatus  35 . The information includes the on-off state of the air-conditioner switch, the temperature of the passenger compartment, and a target temperature. Power is supplied to the solenoid  29   b  of the displacement control valve  29  and several electrical components on the vehicle, which are not shown, from the battery  50 .  
     [0029] Particularly, when the engine Eg is running, upon detection of the off state of the air-conditioning switch or the cooling non-permitting state when the vehicle is rapidly accelerated, the displacement control apparatus  36  fully opens the electromagnetic control valve  29  to minimize the displacement of the compressor CP. Upon detection of the state in which refrigeration is not needed when the engine Eg is stopped, the motor generator MG is stopped.  
     [0030] When the displacement of the compressor CP is minimum, the pressure in the discharge chamber  22  becomes lower than the predetermined value. Thus, the shutoff valve  34  is closed and the discharge of refrigerant gas to the external refrigerant circuit  30  is stopped. As described above, since the minimum inclination angle of the swash plate  12  is not zero degrees, although the displacement of the compressor CP is minimized, refrigerant gas is drawn into the cylinder bores  1   a  from the suction chamber  21 , compressed in the cylinder bores  1   a , and discharged to the discharge chamber  22  from the cylinder bores  1   a . Therefore, an internal refrigerant circuit is formed inside the compressor CP. The internal refrigerant circuit includes the cylinder bores  1   a , the discharge chamber  22 , the supply passage  28 , the crank chamber  5 , the bleed passage  27 , the suction chamber  21 , and the cylinder bores  1   a . Lubricant circulates in the internal refrigerant circuit with refrigerant. Thus, although the compressor CP is operated in the minimum displacement, lubricant is supplied inside the compressor CP.  
     [0031] As shown in FIG. 1, the power transmission mechanism PT includes a drive pulley  51 , a driven pulley  52 , and a belt  53 . The drive pulley  51  is fixed to the output shaft of the engine Eg. The driven pulley  52  is attached to the front end of a first rotary shaft  44 , which projects from the front housing member  41  of the motor generator MG. The belt  53  is wound about the drive pulley  51  and the driven pulley  52 .  
     [0032] The driven pulley  52  includes an outer ring  54 , an inner ring  55 , and a one-way clutch  56 . The belt  53  is wound about the outer ring  54 . The inner ring  55  is secured to the first rotary shaft  44  at the inner circumferential side of the outer ring  54 . The inner ring  55  rotates integrally with the first rotary shaft  44 . The one-way clutch  56  is located between the outer ring  54  and the inner ring  55 . The one-way clutch  56  controls power transmission among the engine Eg, the motor generator MG, and the compressor CP.  
     [0033] That is, as shown in FIGS.  2 ( a ) and  2 ( b ), the inner circumferential surface  54   a  of the outer ring  54  surrounds the outer circumferential surface  55   a  of the inner ring  55 . Accommodating recesses  57  are formed in the inner circumferential surface  54   a  of the outer ring  54  about the axis L at equal intervals. The outer ring  54  rotates counterclockwise as indicated by arrows in FIG. 2. A cam surface  57   a  is formed in each accommodating recess  57  at the trailing end of the outer ring  54 . A roller  58  is accommodated in each accommodating recess  57 . Each roller  58  is movable between a position (FIG. 2( a )) at which the roller  58  is engaged with the corresponding cam surface  57   a  and a position (FIG. 2( b )) at which the roller  58  is apart from the cam surface  57   a . A spring seat  59  is located at the end opposite to the cam surface  57   a  inside each accommodating recess  57 . A spring  60 , which urges the roller  58  toward the cam surface  57   a , is located between each spring seat  59  and the corresponding roller  58 .  
     [0034] As shown in FIG. 2( a ), when the outer ring  54  is rotated in the direction shown by the arrow by the power transmission from the engine EG, each roller  58  moves along the outer circumferential surface  55   a  of the inner ring  55  to an engaging position with the corresponding cam surface  57   a . When each roller  58  is engaged with the corresponding cam surface  57   a , the inner ring  55  is rotated in the same direction as the outer ring  54  by the friction between the cam surface  57   a  and the roller  58 , and the friction between the roller  58  and the outer circumferential surface  55   a  of the inner ring  55 . Therefore, the power of the engine Eg is transmitted to the first and second rotary shafts  44 ,  6  via the one-way clutch  56 . That is, when the engine Eg is running, the motor generator MG and the first and second rotary shafts  44 ,  6  of the compressor CP are always driven.  
     [0035] In contrast, as shown in FIG. 2( b ), when the inner ring  55  is rotated counterclockwise as indicated by the arrow with the first rotary shaft  44  while the engine Eg is stopped, each roller  58  separates from the corresponding cam surface  57   a  against the force of the corresponding spring  60  based on the frictional force between the roller  58  and the inner ring  55 . That is, the inner ring  55  runs idle with the outer ring  54 . That is, although the first rotary shaft  44  is rotated counterclockwise by the motor generator MG that has been put in motion, power is prevented from being transmitted to the engine Eg.  
     [0036] The preferred embodiment provides the following advantages.  
     [0037] The power transmission mechanism PT permits power transmission from the engine Eg to the motor generator MG and prevents power transmission from the motor generator MG to the engine Eg. The power transmission mechanism PT restricts the direction of power transmission by a mechanical structure. Therefore, as compared to the conventional structure that achieves such function by an on-off control of an electromagnetic clutch, the preferred embodiment does not require the electromagnetic clutch or a controller for controlling the electromagnetic clutch. Thus, the structure of the system is simplified and the power consumption of the system is reduced.  
     [0038] The compressor CP and the motor generator MG are arranged in series. The rotary shafts  6 ,  44  are directly coupled to each other on the same axis L. Therefore, a belt or a pulley is not required for power transmission between the rotary shafts  6 ,  44 , which simplifies the structure.  
     [0039] The second rotary shaft  6  of the compressor CP is coupled to the driven pulley  52  of the power transmission mechanism PT via the first rotary shaft  44  of the motor generator MG. Therefore, the second rotary shaft  6  is always driven when the engine Eg is running. However, the air-conditioner has the shutoff valve  34 , which stops circulation of refrigerant via the external refrigerant circuit  30  when refrigeration is not needed and the displacement of the compressor CP is minimized. Therefore, refrigeration is not performed when not needed. Although the displacement of the compressor CP is minimized, lubricant is reliably circulated in the compressor CP. Therefore, although refrigerant that includes lubricant is not returned from the external refrigerant circuit  30 , each sliding part, such as between the swash plate  12  and the shoes  19 , is reliably lubricated.  
     [0040] In the air-conditioner of the preferred embodiment, an expensive and heavy electromagnetic clutch need not be located between the compressor CP and the motor generator MG. Therefore, the weight of a unit, which is formed of the compressor CP and the motor generator MG, is reduced. The unit is also provided at a low cost. Since no shock is caused by turning on and off the electromagnetic clutch, the driving performance of the vehicle is improved.  
     [0041] The compressor CP is operably coupled to the engine Eg downstream of the motor generator MG in the power transmission path. The housing assembly of the compressor CP is easily detachable from the housing assembly of the motor generator MG. The second rotary shaft  6  of the compressor CP is easily detachable from the first rotary shaft  44  of the motor generator MG. Therefore, the compressor CP is easily removed from the unit, which is formed of the compressor CP and the motor generator MG, for a vehicle that requires no refrigeration function.  
     [0042] A second embodiment of the present invention will now be described. The differences from the first embodiment will mainly be discussed below, and like or the same reference numerals are given to those components that are like or the same as the first embodiment.  
     [0043] As shown in FIG. 3, in the second embodiment, the compressor CP and the motor generator MG are arranged in parallel with each other such that the shafts  6 ,  44  extends parallel to each other. Therefore, the length along the axis L of the unit, which is formed of the motor generator MG and the compressor CP, is shortened.  
     [0044] In the second embodiment, the first rotary shaft  44  of the motor generator MG and the second rotary shaft  6  of the compressor CP are operably coupled to each other by the transmission mechanism  75 . The transmission mechanism  75  may be gear-type step transmission mechanism or belt-type continuously variable transmission mechanism. The transmission mechanism  75  allows the rotational speed ratio between the second rotary shaft  6  of the compressor CP and the first rotary shaft  44  of the motor generator MG to be arbitrarily changed.  
     [0045] Therefore, the valid rotational speed ranges of the compressor CP and the motor generator MG differ from each other. Thus, although a problem occurs when the compressor CP and the motor generator MG are directly coupled to each other (rotational speed ratio is 1 to 1), the transmission mechanism  75  can solve the problem by adjusting the rotational speed ratio of the compressor CP and the motor generator MG. This increases flexibility of combination of the compressor CP and the motor generator MG.  
     [0046] The transmission mechanism  75  may be designed such that the rotational speed ratio can be adjusted only when assembling the generator and motor system or during maintenance. The transmission mechanism  75  may also be designed such that the rotational speed ratio can be changed in accordance with the rotational speed of the engine Eg. In the latter case, although the rotational speed of the engine Eg is low, the second rotary shaft  6  of the compressor CP can be rotated at a high speed, which allows sufficient refrigeration. When the rotational speed of the engine Eg is high, the rotational speed of the second rotary shaft  6  can be reduced to protect the compressor CP.  
     [0047] A third embodiment of the present invention will now be described. The differences from the first embodiment will mainly be discussed below, and like or the same reference numerals are given to those components that are like or the same as the first embodiment.  
     [0048] As shown in FIG. 4, in the third embodiment, a cooling system  80  for cooling the inverter  49   a  of the controller  49  is provided. The cooling system  80  includes a first heat exchanger  81 , a second heat exchanger  82 , and a coolant circuit. The first heat exchanger  81  transmits heat generated in the inverter  49   a  to coolant. The second heat exchanger  82  radiates heat of the coolant. The coolant circuit includes a first pump PA, which is used for coolant circulation. When the first pump PA is operated to circulate coolant, the inverter  49   a  is cooled.  
     [0049] The air-conditioner includes a heater circuit  85 , which utilizes cooling water heated by the engine Eg, that is, hot water. The heater circuit  85  includes a heat exchanger  86  and a hot water circuit. The heat exchanger  86  radiates heat from the hot water to the passenger compartment. The hot water circuit includes a second pump PB, which is used for hot water circulation. When the second pump PB is operated to circulate hot water, the passenger compartment is heated.  
     [0050] In the third embodiment, the first pump PA, which is used for coolant circulation, and the second pump PB, which is used for hot water circulation, form a rotational apparatus. The first pump PA is arranged in series with respect to the compressor CP. A rotary shaft  83  of the first pump PA is coupled to the rear end of the second rotary shaft  6  of the compressor CP by a power branching mechanism  88 . The power branching mechanism  88  divides one input from the second rotary shaft  6  of the compressor CP into two outputs.  
     [0051] The second pump PB, which is used for hot water circulation, is arranged in parallel with the first pump PA, which is used for coolant circulation. The rotary shaft  87  of the second pump PB is coupled to the second rotary shaft  6  of the compressor CP by the power branching mechanism  88  and the clutch mechanism  89 . When heating is unnecessary, the clutch mechanism  89  discontinues power transmission between the second pump PB and the second rotary shaft  6  of the compressor CP. This stops the second pump PB, which is used for hot water circulation, and suppresses unnecessary heating.  
     [0052] As described above, in the case in which the rotational apparatuses CP, PA, PB are operably coupled to the motor generator MG, a power source for each rotational apparatus CP, PA, or PB need not be provided for the state in which the engine Eg is stopped. Thus, the entire apparatus is manufactured at a low cost.  
     [0053] It should be apparent to those skilled in the art that the present invention may be embodied in many other specific forms without departing from the spirit or scope of the invention. Particularly, it should be understood that the invention may be embodied in the following forms.  
     [0054] The one-way clutch need not be a roller type but may be a sprag type or a ratchet type.  
     [0055] The one-way clutch  56  may be incorporated in the drive pulley  51  instead of the driven pulley  52 .  
     [0056] In the above embodiments, the rotational apparatuses CP, PA, PB are operably coupled to the engine Eg downstream of the motor generator MG in the power transmission path. However, the rotational apparatuses CP, PA, PB may be coupled to the engine Eg at upstream of the motor generator MG. For example, in the first embodiment, the position of the compressor CP and the motor generator MG may be reversed. Then, the driven pulley  52  may be attached to the front end of the second rotary shaft  6  of the compressor CP and the first rotary shaft  44  of the motor generator MG may be coupled to the rear end of the second rotary shaft  6 .  
     [0057] In the above embodiments, a torque limiter may be located on the power transmission path between the engine Eg and the rotational apparatuses CP, PA, PB. In this case, when the load torque of the rotational apparatuses CP, PA, PB becomes excessive due to, for example, dead lock, while the engine Eg is running, the excessive load torque is prevented from affecting the engine Eg. Particularly, when the torque limiter is located on the power transmission path between the motor generator MG and the rotational apparatuses CP, PA, PB, the motor generator MG generates power even at its torque limit.  
     [0058] In the above embodiments, a clutch mechanism, such as an electromagnetic clutch, may be located on the power transmission path between the motor generator MG and the compressor CP. In this case, when refrigeration is not needed while the engine Eg is running, the compressor CP is stopped by the operation of the clutch mechanism. Thus, a structure for a clutchless compressor CP such as the shutoff valve  34  can be omitted.  
     [0059] The rotational apparatus may be any apparatus that operates in accordance with input of rotational force from the outside. For example, the rotational apparatus includes a hydraulic pump for a brake assist system, a hydraulic pump for a power steering apparatus, an air pump for an air suspension system, and a pump for coolant circulation of a cooling system for cooling the motor generator MG or the battery  50 .  
     [0060] The generator and motor system of the present invention may be applied to watercrafts.