Abstract:
Three shafts of a planetary gear mechanism, which is a torque distribution mechanism, are connectable to an engine, a motor-generator and a compressor, respectively. An engine connecting shaft, a motor-generator connecting shaft and an accessory equipment connecting shaft are connected to a ring gear, a carrier and a sun gear, respectively. A single motor-generator can perform four different operations: a compressor driving operation when an idle stop function is performed, an engine starting operation by the motor-generator, a motor-generator driving operation by the engine, motor-generator driving and compressor driving operations by the engine.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is based on and incorporates herein by reference Japanese Patent Application No. 2001-111054 filed on Apr. 10, 2001. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to an accessory equipment driving device for a vehicle. 
     As a technology to improve fuel economy, a vehicle having an idle stop function that stops an engine at idle is proposed. In this type of vehicle, the idle stop function is canceled in order to drive a compressor for an air conditioner by the engine. Therefore, the idle stop function is not fully effective. 
     To counter this problem, a hybrid-compressor with an integrated motor is proposed in JP-A-2000-229516. This hybrid-compressor is driven by the engine when the engine is running. When the engine is not running, the compressor is disconnected from the engine and driven by the motor. To disconnect the compressor from the engine, a clutch mechanism, such as a one-way clutch or a clutch, is required. In other word, a motor and its driving control circuit, and a clutch mechanism are required. This increases complexity of configuration and a cost. Moreover, additional electrical circuits, such as an inverter circuit, to control a driving operation of the compressor are required. 
     Here, a power generating system (rotary electric machine and electrical circuit) can be simplified with a configuration in which the motor is driven to generate electricity. 
     An ideal condition of connections among the engine, rotary electric machine, and compressor for an air conditioner will be analyzed. 
     When the engine is started, the engine and the rotary electric machine need to be connected, and the compressor is better not to be connected with the engine nor the rotary electric machine (motor operation). 
     When the engine is running with the air conditioner off, the engine and the rotary electric machine need to be connected, and the compressor is better not to be connected with the engine nor the rotary electric machine (motor operation). 
     When the engine is running with the air conditioner on, the engine, the rotary electric machine, and the compressor need to be connected. 
     When the idle stop function is performed, the engine is better not to be connected with the rotary electric machine nor the compressor, and the rotary electric machine and the compressor need to be connected so that proper operations of the air conditioner are ensured. 
     In the accessory equipment driving device for a vehicle having an idle stop function, these connections need to be accomplished with simple configuration. 
     SUMMARY OF THE INVENTION 
     The present invention has an objective to provide an accessory equipment driving device for a vehicle with high installability to a vehicle, simple system configuration, and good cost efficiency. 
     An accessory equipment driving device for a vehicle of the present invention makes connections among an engine having an idle stop function, a motor-generator for a power generating operation and a motor operation, and accessory equipment such as a compressor for an air conditioner. 
     This device is for driving the accessory equipment by the engine when the engine is running, and by the motor-generator when the engine is idle. The device has an engine connecting shaft, a motor-generator connecting shaft, an accessory equipment connecting shaft. The shafts are to be connected to the engine, the motor-generator, and the accessory equipment, respectively. 
     The device has a torque distribution mechanism. This mechanism is for distributing engine torque inputted through the engine connecting shaft to the motor-generator connecting shaft and accessory equipment connecting shaft. It is also for transferring torque inputted through the motor-generator connecting shaft to the engine connecting shaft. 
     The device has a locking mechanism which locks the accessory equipment connecting shaft, and a clutch which disengageably connects the motor-generator connecting shaft of the torque distribution mechanism with the accessory equipment connecting shaft. 
     According to the above configuration, a single motor-generator can perform four different operations: a driving operation of the compressor when the idle stop function is performed, a starting operation of the engine by the motor-generator, a driving operation of the motor-generator by the engine, and a driving operation of both motor-generator and the compressor by the engine. Therefore, the motor-generator and its driving circuit can be integrated, and the configuration can be simplified. 
     Moreover, a motor-generator/accessory equipment system which consists of the compressor, motor-generator, torque distribution mechanism, clutch and locking mechanism can be separately placed from the engine. Therefore, a total shaft length of the engine can be reduced. This improves arrangement flexibility in an engine compartment, resulting in improved installability of the device, especially in small vehicles. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objectives, 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: 
     FIG. 1 is a block diagram of an accessory equipment driving device according to the embodiment; and 
     FIG. 2 is an operation mode diagram showing operation modes of the accessory equipment driving device of FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The preferred embodiment of the present invention will be explained with reference to the accompanying drawings. 
     Referring to FIG. 1, the configuration and operation of the accessory equipment driving device for a vehicle of this embodiment is discussed. 
     An internal combustion engine  1  has an idle stop function. The engine  1  is stopped during idling. A crank pulley  2  has a belt  3  for transferring a driving power generated by the engine  1  to other devices. A motor-generator/accessory equipment system  4  will be explained later. An electricity storing device  5 , such as a secondary battery, stores electricity. A three-phase inverter  6  has a DC-AC bidirectional conversion function. It mediates between the electricity storing device  5  and the motor-generator/accessory equipment system  4  for power transfer. 
     A control device  7  sets a mode to a starter mode, an alternator mode, an electrical compressor mode, or an internal combustion engine driven compressor mode. The mode is determined based on information provided by an internal combustion engine control device or an air-conditioner control device, which are not shown in figures. The control device  7  controls the inverter  6 , clutch  430  of the motor-generator/accessory equipment system, and locking mechanism  460 . An electrical load  8  receives a power from the electricity storing device  5 . 
     The motor-generator/accessory equipment system  4  includes an input pulley  410  connected to the crank pulley  2  of the engine  1  by the belt  3 . A planetary gear mechanism  420  refers to the torque distribution mechanism of this embodiment. It includes the first shaft  421 , second shaft  422 , third shaft  423  and ring gear  424 . The ring gear  424  is fixed to the first shaft  421 , and the first shaft  421  is directly connected to a rotor shaft of the motor-generator  440 . A carrier  425  is fixed to the second shaft  422 , and the second shaft  422  is directly connected to the input pulley  410 . The third shaft  423  is connected to the first shaft  421  via the clutch  430  and to the compressor  450  for an air conditioner via the locking mechanism  460 . 
     In the planetary gear mechanism  420 , the sun gear and ring gear are engaged with the planet gears. The planet gears are supported by the carrier  425  as they rotate their own axes. The carrier  425  is rotated as the planet gears revolve around the sun gear  426 . 
     Since the third shaft  423  of the planetary gear mechanism is connected to one of the shafts of the locking mechanism  460  and that of the clutch  430 , the clutch  430  and locking mechanism  460  can be integrated. Likewise, the clutch  430  and planetary gear mechanism  420 , or the clutch  430 , locking mechanism and planetary gear mechanism can be integrated. 
     Moreover, the motor-generator  440  and clutch  430 , or the locking mechanism and compressor  450  can be integrated. A rotary electric machine which a planetary gear mechanism is integrated can be used for the planetary gear mechanism  420  and motor-generator  440 . Furthermore, the clutch  430 , locking mechanism  460 , and compressor  450  can be connected or integrated to the motor-generator. 
     A driveline device includes the planetary gear mechanism  420 , clutch  430 , and locking mechanism  460 . In this device, whether simultaneously rotating the second shaft  422  and the third shaft  423  of the planetary gear mechanism  430 , or independently rotating them is determined. Conventional electromagnetic or hydraulic clutch can be used for the clutch  430 . 
     Although a synchronous motor-generator is used for the motor-generator  440 , other types of motor-generator can be used as long as a selection between the power generating operation and motor operation is available. The compressor  450  is a conventional compressor for an automobile air conditioner. The locking mechanism  460  may be a conventional braking mechanism. 
     (I) Engine Starting Mode 
     When restarting the engine  1  after it stopped by the idle stop function, the clutch  430  is released (disconnected) and the locking mechanism  460  is locked. 
     This stops rotations of the third shaft  423  and the sun gear  426  of the planetary gear mechanism  420 . A rotor shaft of the motor-generator  440  is mechanically connected to the input pulley  410  via the ring gear  424  and the carrier  425  of the planetary gear mechanism  420  one after another. The control device  7  controls the inverter  6  so that the motor-generator  440  performs a motor operation to provide the engine  1  with starting torque. The number of rotations of the carrier  425  is smaller than that of the ring gear  424 ; therefore, the electrical torque of the motor-generator  440  is multiplied and large starting torque is provided to the engine  1 . 
     (II) Power Generating Mode During Halting of Compressor 
     When a starting operation of the engine  1  is completed, the control device  7  controls the inverter  6  so that the motor-generator  440  performs a power generating operation. A power generated by the motor-generator  440  is rectified by the inverter  6 , and charged into the electricity storing device  5 . A power is supplied to the electrical load  8 . At this moment, the clutch  430  is released, the locking mechanism  460  is locked, and the compressor  450  is stopped. 
     (III) Compressor Driving Mode During Idle Stop 
     When driving the compressor  450  to drive an air conditioner while the engine  1  is not running, the clutch  430  and the locking mechanism  460  are released, and the motor-generator  440  performs a motor operation. This disables the second shaft  422  of the planetary gear mechanism  420  to rotate due to a friction of the engine  1 . As a result, the torque of the motor-generator  440  is transferred from the ring gear  424  to the compressor  450  via the sun gear  426  and the third shaft  423  of the planetary gear mechanism  420 . The control device  7  drives the inverter  6  and supplies an alternating current to the motor-generator  440  so that torque necessary for rotating the compressor  450  is generated. 
     (IV) Compressor Driving Mode During Running of Engine 
     When the engine  1  is running, the motor-generator  440  performs a power generating operation as described above. At this time, the clutch  430  is engaged and the locking mechanism  460  is released to drive the compressor  450 . By this operation, the first shaft  421  and third shaft  423  of the planetary gear mechanism have the same number of rotations. Therefore, the motor-generator  440  and compressor  450  are driven at the same speed as a result of the engine rotation. 
     “STARTER,” “ONLY ALTER.,” “ELEC. A/C” and “NORM. ALTER., A/C” in the table of FIG. 2 corresponds to the “Engine Starting Mode,” “Power Generating Mode during Halting of Compressor,” “Compressor Driving Mode During Idle Stop” and “Compressor Driving Mode During Running of Engine” which are discussed above, respectively. 
     The present invention should not be limited to the embodiment previously discussed and shown in the figures, but may be implemented in various ways without departing from the spirit of the invention. 
     For example, the planetary gear mechanism  420  is used for a torque distribution mechanism in the above embodiment. However, a differential gear mechanism can be used. Other types of planetary gear mechanism can be used for the planetary gear mechanism  420 . For the clutch mechanism, any two of the first to third shafts of the planetary gear mechanism  420  instead of the first and third shafts can be connectable.