Abstract:
The present invention provides a vehicle-drive system which can recovers inertial power from a vehicle. Torque of an internal-combustion engine is transferred to input shaft of transmission through main clutch. Dynamo-electric-machine mechanism is connected to input shaft of transmission through assistant clutch, and further, accessories are connected to dynamo-electric-machine mechanism. Therefore, in simple structure, substantially added by only assistant clutch relative to conventional structure, plural manners of operation can be realized by connecting or disconnecting two clutches thereby attaining other superior effects such as fuel-cost savings.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present invention is related to Japanese patent application No. Hei. 11-208266, filed Jul. 22, 1999; the contents of which are incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention relates to a vehicle-drive system, and more particularly, to a vehicle-drive system, which recovers inertial energy from a vehicle. 
     BACKGROUND OF THE INVENTION 
     In conventional vehicle-drive systems, torque from an internal-combustion engine is transferred to a vehicle drive shaft through a main clutch, an input shaft and a transmission. A starter, a generator motor and accessories for the vehicle-operating system are connected to a crank shaft through a belt drive system. However, when the vehicle is no longer accelerating, the inertial energy of the vehicle supplies energy from the wheels to the engine, and then to the vehicle accessories. However, in this system, when the generator and accessories are driven by inertial power of the vehicle, the inertial power of the vehicle cannot effectively be recovered due to friction loss from the internal-combustion engine, resulting in little fuel-cost savings. Moreover, when the vehicle is braked, the vehicle looses even more inertial energy due to the braking operation. The present invention was developed in light of these drawbacks. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a vehicle-drive system, which drastically improves recovery of inertial power of a vehicle lost due to braking. 
     It is a further object of the present invention to provide the above described system while avoiding structural complication thereof. 
     It is yet another object of the present invention to aid the internal combustion engine when the engine is being started or is operating under a large load. 
     The present invention achieves the above-described objects by providing a device that transfers torque from an internal-combustion engine of a vehicle-drive system to a transmission through a main clutch. A dynamo-electric-machine mechanism is connected to an input shaft of the transmission through an assistant clutch. Accessories are connected to the dynamo-electric-machine mechanism. Different modes of operation are then achieved by connecting and disconnecting the main and assistant clutch. 
     In another aspect of the present invention, a torque converter with a lock mechanism is used. The torque converter is disposed between the input shaft of the transmission, the main clutch and the assistant clutch. In this aspect, both the clutches can be attached to an input shaft of the torque converter. However, where this torque converter is used, it is preferable that the torque converter with a lock mechanism is employed for brake operation and is locked during braking of the vehicle. 
     In a further aspect of the present invention, the accessories are connected to the input shaft of the transmission through the assistant clutch. 
     In another aspect of the present invention, the dynamo-electric-machine mechanism drives the accessories with the assistant clutch disconnected when the internal-combustion engine and the vehicle are not operating. Here, when the internal-combustion engine is started, the dynamo-electric-machine mechanism drives the internal-combustion engine through both clutches while both are connected. The vehicle recovers inertial power when it is braked through the assistant clutch, while the main clutch is disconnected. When the internal-combustion engine is started, the vehicle is driven by the internal-combustion engine through both the clutches. Therefore, inertial power from the vehicle is recovered by the dynamo-electric-machine mechanism instead of being lost as friction in the internal-combustion engine. When the internal-combustion engine is started, the transmission is shifted to neutral or park. Accordingly, the output shaft of the transmission is not driven by the dynamo-electric-machine mechanism. 
     When the internal-combustion engine is operated, the dynamo-electric-machine mechanism is driven by the internal-combustion engine through both the clutches. However, when operating, the internal-combustion engine supplies power through the transmission. When idling, the internal-combustion engine supplies torque to the dynamo-electric-machine mechanism and the accessories while preventing torque from being transferred through the transmission. This is accomplished by shifting the transmission to the neutral position or the parking position or by depressing a brake pedal with the torque converter being added to the transmission. 
     In another aspect of the invention, the accessories are connected to the dynamo-electric-machine mechanism not through the clutch. The accessories recover inertial power from the vehicle through the assistant clutch with the main clutch disconnected. The accessories are driven together with the dynamo-electric-machine mechanism by the internal-combustion engine through both the clutches when the internal-combustion engine is operated. 
     In another aspect of the invention, the dynamo-electric-machine mechanism operates electrically and assists the internal-combustion engine in supplying torque for running. This assisted torque is supplied through the assist clutch, connected when the engine undergoes a large running load, while operating. Therefore, larger torque can be obtained. 
     In another aspect of the invention, both clutches are connected to make the dynamo-electric-machine mechanism generate electricity during major brake operations of the vehicle wherein the vehicle is decelerated quickly. The vehicle can be braked due to both friction loss of the internal-combustion engine and recovery-electric power of the dynamo-electric-machine mechanism. 
     The accessories can be connected directly to the dynamo-electric-machine mechanism through the torque-transfer mechanism, or to the input shaft of the transmission through the torque-transfer mechanism. Further, the accessories can be connected to the torque-transfer mechanism as described above through an added clutch. 
     In another aspect of the invention, an undulating lever for the main clutch and an undulating lever for the assistant clutch are disposed around the input shaft of the transmission, with their undulating spaces being overlapped in axial directions thereof. The undulating lever for the main clutch is a portion of an impelling mechanism for connecting or disconnecting the main clutch. The undulating lever for the assistant clutch is a portion of an impelling mechanism for connecting or disconnecting the assistant clutch. Therefore, the input shaft of the transmission (including a shaft of a disk connected to the input shaft of the transmission) can be shortened, thereby making the structure of the system more compact. Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are intended for purposes of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
     FIG. 1 is a block diagram of a vehicle-drive system according to a first embodiment of the present invention; 
     FIG. 2 is a flowchart showing operation of the vehicle-drive system shown according to the present invention; 
     FIG. 3 is a flowchart showing operation of the vehicle-drive system according to the present invention; 
     FIG. 4 is a cross-sectional view of a clutch mechanism for a vehicle-drive system according to the present invention; 
     FIG. 5 is block diagram of the vehicle-drive system according to a second embodiment of the present invention; and 
     FIG. 6 is a cross-sectional view of a clutch mechanism of a vehicle-drive system according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In a vehicle-drive system according to the present invention, a dynamo-electric-machine mechanism is operationally engaged with an input shaft of a transmission. The dynamo-electric-machine mechanism includes a single generator motor, or multiple other devices such as a starter motor and an alternator. 
     In FIG. 1, a first embodiment of the present invention provides a vehicle-drive system which includes internal combustion engine  1 , transmission  2 , clutch mechanism  3 , belt mechanism  4  (torque-transfer mechanism), generator motor  5  (dynamo-electric-machine mechanism), accessories  6 , three-phase inverter  7 , battery  8 , and differential gear  9 . 
     Clutch mechanism  3  includes main clutch  31  and assistant clutch  32 . Main clutch  31  is provided between input shaft  20  of transmission  2  and crankshaft  10  of internal combustion engine  1 . Assistant clutch  32  is provided between input shaft  20  and a pulley supporting belt mechanism  4 . Generator motor  5  and accessories  6 , such as an air-conditioning compressor (not shown), serially communicate with input shaft  20  of transmission  2  through belt mechanism  4  and assistant clutch  32 . 
     Belt mechanism  4  includes pulley  42  supported by input shaft  20  allowing it to move in a rotational direction thereof through bearing  41 , pulley  43  to which generator motor  5  and accessories  6  are connected, and belt  44  for coupling both pulleys  42 ,  43 . 
     The generator motor  5 , which is a three-phase brushless DC motor, gives electric power to battery  8  and receives it therefrom through three-phase inverter  7  and the battery. Here, three-phase inverter  7  includes three pairs of upper-arm-side devices and three pairs of lower-arm-side devices, which are not shown in the drawing. Each of the devices is composed of a switching element such as an IGBT and a flywheel diode, which are connected in inverse parallel. 
     Controller  100  controls main clutch  31 , assistant clutch  32  and three-phase inverter  7 . Three-phase inverter  7 , in turn, controls generator motor  5 . Since the control of three-phase inverter  7  for generator motor  5  is well known, it is not explained. 
     In a first control operation, internal-combustion engine  1  is started by a dynamo-electric-machine mechanism. Here, when internal-combustion engine  1  receives a start-command signal, controller  100  detects and determines whether transmission  2  is in neutral or park. If either are true, main clutch  31  and assistant clutch  32  are connected. Generator motor  5  is then operated electrically and internal-combustion engine  1  is started. 
     In a second control operation, the dynamo-electric-machine mechanism generates electricity and drives accessories with the internal-combustion engine. After the internal-combustion engine is started, controller  100  drives accessories  6  with internal-combustion engine  1  through main clutch  31  and assistant clutch  32 , while switching the operation of generator motor  5  from electrical-drive operation to power-generation operation. Thereafter, when a vehicle runs according to the operation of transmission  2 , the same operation as described above is performed. 
     In a third control operation, inertial power from a vehicle is recovered without friction loss by the internal-combustion engine by the dynamo-electric-machine mechanism and accessories. When controller  100  detects brake operation or receives a signal corresponding to an accelerator pedal being released, it disconnects main clutch  31 , connects assistant clutch  32 , and actuates generator motor  5  to generate electricity. Thus, generator motor  5  and accessories  6  are driven by inertial power from a vehicle, and battery  8  is charged by the generated electric power. 
     In a fourth control operation, internal-combustion engine  1  is assisted in supplying torque for vehicle operation either when the vehicle starts running or while running. When the vehicle starts running, controller  100  assists internal-combustion engine  1  in supplying torque to the vehicle by electrically driving generator motor  5  to aid internal-combustion engine  1 . Alternatively, controller  100  stops generator motor  5  from generating power, thereby reducing the load on internal-combustion engine  1 . Similarly, if the accelerator pedal is largely depressed while the vehicle is running, controller  100  reduces the load on internal-combustion engine  1  by electrically driving generator motor  5  or stopping power generation thereof. 
     In a fifth control operation, a damping operation is provided for the vehicle engine. Here, controller  100  controls power-generation quantity or electrical-drive quantity of generator motor  5  in a phase opposite to torque fluctuation of internal-combustion engine  1 . As a result, fluctuation of torque output from internal-combustion engine  1  is reduced, thereby reducing vibration and noise. 
     In a sixth control operation, a major brake operation is provided for the vehicle. When the brake pedal is largely depressed, controller  100  electrically drives generator motor  5  by connecting both main clutch  31  and assistant clutch  32 , thereby recovering inertial power from the vehicle as generated electric-power. This recovered power is used as braking power for assistance of the brake force. As a result of this power usage, wear of the vehicle&#39;s brake friction pad is reduced. This recovered power is used as driving power for accessories and friction losses of the engine. 
     In a seventh control operation, the vehicle is moved with generator motor  5 . When internal-combustion engine  1  is stopped, main clutch  31  is disconnected and assistant clutch  32  is connected. The vehicle is then moved by electrical operation of generator motor  5 . 
     The above-mentioned control operation of controller  100  is shown in a flowchart in FIG.  2 . Here, as shown in FIG. 2, the process begins at block  400  start. Next, the flow chart moves to block  402  where it is determined whether a command signal is received by the controller  100 . If this is true, the generator  5  is operated under electric drive mode. Then, the program moves to block  406  and determines whether starting is completed. If not, the program continues in electric drive mode until starting is completed. Once starting is complete, or if a no decision is observed in  402 , block  408  is executed next. Here, generator  5  is operated under power generation mode. Next, it is determined whether there is a brake command signal in block  410 . If none, the program ends. If there is a brake command, the program moves to block  412  where the value of the brake signal is determined, as indicated by the controlled variable. If the controlled variable is not large, then the program moves to block  416 . Here, clutch  31  is disconnected and clutch  32  is connected since there is not a large amount of braking force that must be supplied. Generator  5  is also operated under a power generation mode. If the controlled variable is determined to be large, then the program moves to block  414 . Here, it is determined whether the battery is fully charged. If so, block  420 , clutch  31  and clutch  32  are engaged in block  420  to absorb braking force. If not, in Block  418 , clutches  31  and  32  are engaged, and generator  5  is operated under a power generation mode to charge the batteries. 
     Referring now to FIG. 3, a second process is shown beginning in block  450 . In block  452 , an acceleration command is sensed. If the vehicle is accelerated, both clutches  31  and  32  are engaged and the generator  5  is operated under electrical driving mode in block  454  to assist the engine. If no acceleration, then block  454  is skipped. In block  456 , a driving signal for driving the accessories is sensed. If this signal is sensed, block  458  determines whether the vehicle is being braked. If the vehicle is being braked, then block  460  disconnects clutch  31 , connects clutch  32 . If the vehicle is not being braked, then block  462  disconnects clutch  32  and maintains generator  5  in a power generation mode. 
     Referring now to FIG. 4, clutch mechanism  3  is explained in greater detail. Clutch casing  11  is clamped between and fastened to internal-combustion engine  1  and transmission  2 . A tip  422  of input shaft  20  of transmission  2  is mounted onto crank shaft  10 , rotatably supported by bearing  424 . 
     Main clutch  31  includes internal-combustion-engine-side disk  310  fixed to crank shaft  10 , input-shaft-side disk  311 , impelling tube  312  and undulating lever  313 . Input-shaft-side disk  311  is splined to input shaft  20  to allow relative movement therebetween in an axial direction. However, the splines prohibit rotational movement. Impelling tube  312  is fit around input shaft  20  of transmission  2  and is axially and rotationally moveable along input shaft  20 . Impelling tube  312  impels input-shaft-side disk  311  in the axial direction thereof. Undulating lever  313  impels impelling tube  312  in an axial direction thereof by undulating so as to move like a see-saw. 
     Impelling tube  312  includes base tube  3120  and bearing  3121  attached to base tube  3120 . Base tube  3120  axially and rotationally slide along input shaft  20 . 
     Undulating lever  313 , whose tip only is shown in FIG. 4, is supported by clutch casing  11  so as to undulate and move like a see-saw in its horizontal plane. Its base end is impelled by an oil hydraulic cylinder, and its tip impels an outer ring of bearing  3121  in the axial direction of input shaft  20 . 
     Undulating lever  313  is made to undulate so as to move like a see-saw, caused by an oil hydraulic cylinder, so that the outer ring of bearing  3121  thereof is impelled to the right-side direction in FIG.  4 . This axial thrust slides impelling tube  312  to the right-side direction in FIG.  4  through an inner ring of bearing  3121 . Impelling tube  312  impels input-shaft-side disk  311  to the right-side direction through thrust spring  3122  or the like. Thus, input-shaft-side disk  311  is released from internal-combustion-engine-side disk  310 , so that main clutch  31  is disconnected. 
     If undulating lever  313  is moved in the opposite direction to the above-described case, its tip impels the outer ring of bearing  3121  to the left-side direction in FIG.  4 . Then, this axial thrust slides impelling tube  312  to the left-side direction in FIG.  4  through the inner ring of bearing  3121 , and impelling tube  312  impels input-shaft-side disk  311  to the left-side direction through thrust spring  3122  or the like. Thus, input-shaft-side disk  311  is thrust into internal-combustion-engine-side disk  310 , so that main clutch  31  is connected. 
     Assistant clutch  32  includes a pulley  42  (an accessory-side disk) attached to input shaft  20 , rotationally supported by bearing  41 . Assistant clutch  32  also includes an input-shaft-side disk  321 , impelling tube  322  and undulating lever  323 . Input-shaft-side disk  321  is splined to input shaft  20  to allow axial movement but not rotational movement therebetween. Impelling tube  312  impels input-shaft-side disk  321 . Impelling tube  312  is splined to base tube  3120  of impelling tube  312  to provide axial but not radial movement therebetween. Undulating lever  323  impels impelling tube  322  in an axial direction thereof by undulating about point  200  to move like a see-saw. 
     Impelling tube  322  includes base tube  3220  and bearing  3221  attached to base tube  3220 . Base tube  3220  is attached to base tube  3120  of impelling tube  312  of main clutch  31  so as to move relative thereto in an axial direction thereof but so as not to move relative thereto in a rotational direction thereof. 
     Undulating lever  323  is supported by clutch casing  11  so as to undulate and move like a see-saw in its vertical plane, and its base end is impelled by an oil hydraulic cylinder not shown in the drawing. Undulating lever  323  has a tip which impels an outer ring of bearing  3221  in the axial direction of input shaft  20 . 
     When undulating lever  323  is moved by the oil hydraulic cylinder, the outer ring of bearing  3221  thereof is impelled to the right-side direction in FIG.  4 . This axial thrust slides impelling tube  322  to right-side direction in FIG.  4  through an inner ring of bearing  3221 . As a result, impelling tube  322  moves input-shaft-side disk  321  to the right-side direction through thrust spring  3222 . Thus, input-shaft-side disk  321  is thrusted into pulley  42 , thereby connecting clutch  32 . 
     If undulating lever  323  is moved in the opposite direction, its tip impels the outer ring of bearing  3221  to the left-side direction in FIG.  4 . Then, this axial thrust slides impelling tube  322  to the left-side direction in FIG.  4  through the inner ring of bearing  3221 . Impelling tube  322  impels input-shaft-side disk  321  to the left-side direction through thrust spring  3222  or the like. Thus, input-shaft-side disk  321  is released from pulley  42 , so that assistant clutch  31  is disconnected. 
     Referring now to FIG. 5, a vehicle-drive system according to a second embodiment of the present invention has a generator motor  5   a  attached to input shaft  20  of transmission  2  so as to move in the rotational direction thereof in the vehicle-drive system shown in FIG.  1 . 
     Generator motor  5   a , for example, is composed of a three-phase brushless DC motor, and includes a rotor and a stator surrounding the rotor. The rotor is supported by input shaft  20  of transmission  2 , supported by a pair of bearings, rotatably movable. Pulley  42 , also shown in the first embodiment, is fixed to the rotor. Assistant clutch  32  is provided between pulley  42  and input shaft  20  of transmission  2 , and has substantially the same structure as shown in the first embodiment. Pulley  43  of accessories  6  is driven by pulley  42  through belt  44 . 
     Clutch mechanism  3 , as shown in FIG. 6, is similar to the first embodiment (shown in FIG.  4 ), with the addition of generator motor  5   a . The rotor of generator motor  5   a  is fixed to pulley (accessory-side disk)  42  by bolts, and the stator thereof is fixed to clutch casing  11 . 
     In the above-described embodiment, assistant clutch  32  is attached to input shaft  20  of transmission  2 . However, assistant clutch  32  can be contained in pulley  43  inside generator motor  5 . Preferably, accessories  6  are connected to generator motor  5  not through assistant clutch  32 . However, theses elements may be connected through assistant clutch  32 . 
     While the above-described embodiments refer to examples of usage of the present invention, it is understood that the present invention may be applied to other usage, modifications and variations of the same, and is not limited to the disclosure provided herein.