Power transmitting apparatus for hybrid vehicle Number:7,108,087 from the United States Patent and Trademark Office (PTO) owispatent

Title: Power transmitting apparatus for hybrid vehicle

Abstract: The present invention provides a power transmitting apparatus that uses a small configuration to efficiently carry out various forms of propulsions such as a speed change propulsion and even an EV propulsion (electric propulsion) including a series type EV propulsion. The power transmitting apparatus includes a clutch 8 that connects and disconnects rotation transmissions between an output shaft 1a of an engine 1 and an input shaft 4r of one 4 of two power distributors 4 and 5 to which a rotational drive force is transmitted by the engine 1, a clutch 9 that connects and disconnects rotation transmissions between one of two output shafts 5c, 5c of the power distributor 5 and a power output shaft 12, and rotation regulating means 10 and 11 that properly inhibit rotation of the input shaft 4r of the power distributor 4 and rotation of the output shaft 5c of the power distributor 5. Motors 6 and 7 apply torques to an output shaft 4s of the power distributor 4 and an output shaft 5s of the power distributor 5, respectively.

Patent Number: 7,108,087 Issued on 09/19/2006 to Imai

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Inventors:	Imai; Nobuyuki (Wako, JP)
Assignee:	Honda Motor Co., Ltd. (Tokyo, JP)
Appl. No.:	10/863,276
Filed:	June 9, 2004

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Foreign Application Priority Data

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Jun 12, 2003 [JP]			2003-168346
Jun 18, 2003 [JP]			2003-173378

Current U.S. Class:	180/65.2 ; 180/65.4; 477/3; 903/926
Current International Class:	B60K 6/04 (20060101)
Field of Search:	180/65.1,65.2,65.3,65.4 903/902,903,926,951 477/3,5 318/8,34,87

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References Cited [Referenced By]

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U.S. Patent Documents

	5730676		March 1998		Schmidt
	6248036		June 2001		Masaki
	6520879		February 2003		Kawabata et al.
	6555927		April 2003		Suzuki et al.
	6691809		February 2004		Hata et al.
	6890283		May 2005		Aoki

Foreign Patent Documents

	11-301291		Nov., 1999		JP
	2002-052944		Feb., 2002		JP

Primary Examiner: Ellis; Christopher P.
Assistant Examiner: Swenson; Brian L.
Attorney, Agent or Firm: Arent Fox, PLLC.

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Claims

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What is claimed is:

1. A power transmitting apparatus for a hybrid vehicle comprising a first and second power distributors each having an input shaft to which a rotational drive power from an engine is transmitted, a power output shaft to which a first output shaft of two output shafts of said first power distributor and a first output shaft of two output shafts of said second power distributor transmit rotational drive powers and which output the transmitted rotational drive powers to drive wheels of the vehicle, a first motor that applies a drive torque or regenerative torque to a second output shaft of said first power distributor, and a second motor that applies a drive torque or regenerative torque to a second output shaft of said second power distributor, a speed reduction ratio for a rotation transmitting system from said engine to said power output shaft via said first power distributor having a value different from a value of a speed reduction ratio for a rotation transmitting system from said engine to said power output shaft via said second power distributor, wherein the apparatus comprises first clutch means for connecting and disconnecting said engine to and from the input shaft of said first power distributor for rotation transmission, second clutch means for connecting and disconnecting the first output shaft of said second power distributor to and from the power output shaft for rotation transmission, first rotation regulating means operating in an open state in which the input shaft of said first power distributor is rotatable and in a braking state in which the input shaft is inhibited from rotating, and second rotation regulating means operating in an open state in which the first output shaft of the second power distributor is rotatable and in a braking state in which the first output shaft s inhibited from rotating.

2. The power transmitting apparatus for a hybrid vehicle according to claim 1, wherein each of said first and second power distributors comprises a pinion gear device.

3. The power transmitting apparatus for a hybrid vehicle according to claim 2, wherein the input shaft, first output shaft, and second output shaft of each of said power distributors are a ring gear, a carrier, and a sun gear of the pinion gear device respectively constituting the power distributor.

4. The power transmitting apparatus for a hybrid vehicle according to any of claim 1 to 3, wherein said first rotation regulating means comprises a one-way clutch for inhibiting only rotation of the input shaft of said first power distributor in a predetermined one of two rotating directions.

5. The power transmitting apparatus for a hybrid vehicle according to claim 4, wherein said first rotation regulating means further comprises forced braking means for inhibiting rotation of the input shaft of said first power distributor via an actuator.

6. The power transmitting apparatus for a hybrid vehicle according to claim 1, wherein said second rotation regulating means comprises a one-way clutch for inhibiting only rotation of the first output shaft of said second power distributor in a predetermined one of two rotating directions.

7. The power transmitting apparatus for a hybrid vehicle according to claim 6, wherein said second rotation regulating means further comprises forced braking means for inhibiting rotation of the first output shaft of said second power distributor via an actuator.

8. The power transmitting apparatus for a hybrid vehicle according to claim 1, wherein said first and second clutch means are operated in a connected state and said first and second rotation regulating means are operated in an open state in a speed change propulsion mode, and the speed change propulsion mode is a mode in which the vehicle is propelled by transmitting the rotational drive power of said engine to said power output shaft via said first and second power distributors while generating a drive torque in one of said first and second motors and a regenerative torque in the other and in which the torques generated by said first and second motors are controlled to control a speed change ratio between the engine to the power output shaft.

9. The power transmitting apparatus for a hybrid vehicle according to claim 8, wherein said first and second clutch means are operated in a disconnected state and said first rotation regulating means operates in a braking state in an electric propulsion mode, and the electric propulsion mode is a mode in which the drive torque of said first motor is transmitted to said power output shaft to start and propel the vehicle.

10. The power transmitting apparatus for a hybrid vehicle according to claim 9, wherein a rotation transmitting system from said first motor to said power output shaft via said first power distributor has a higher speed reduction ratio than a rotation transmitting system from said second motor to said power output shaft via said second power distributor.

11. The power transmitting apparatus for a hybrid vehicle according to claim 9, wherein said first rotation regulating means comprises a one-way clutch for inhibiting only rotation of the input shaft of said first power distributor in a predetermined one of the two rotating directions and forced braking means for inhibiting rotation of the input shaft of said first power distributor via the actuator, and wherein when the vehicle is propelled forward in the electric propulsion mode, said first motor is caused to generate a drive torque that advances the vehicle, while said first rotation regulating means is operated in the braking state using its one-way clutch, and when the vehicle is propelled backward in the electric propulsion mode, said first motor is caused to generate a drive torque in a direction inverse to that of the drive torque generated when the vehicle is propelled forward, while said first rotation regulating means is operated in the braking state using its forced braking means.

12. The power transmitting apparatus for a hybrid vehicle according to claim 11, wherein the drive torque of said second motor is transmitted to said engine to start the engine in a state that said first and second clutch means are operated in the disconnected state and said second rotation regulating means is operated in the braking state, before the vehicle starts traveling backward in said electric propulsion mode.

13. The power transmitting apparatus for a hybrid vehicle according to claim 12, wherein said second rotation regulating means comprises a one-way clutch for inhibiting only rotation of the first output shaft of said second power distributor in a predetermined one of the two rotating directions, and when said engine is started before said vehicle starts traveling backward, the second rotation regulating means is operated in the braking state using its one-way clutch.

14. The power transmitting apparatus for a hybrid vehicle according to claim 9, wherein said electric propulsion mode includes a series type electric propulsion mode in which the rotational drive power of said engine is transmitted to said second motor to allow the second motor to generate a regenerative power, and in the series type electric propulsion mode, said second rotation regulating means is operated in the braking state.

15. The power transmitting apparatus for a hybrid vehicle according to claim 14, wherein the drive torque of said second motor is transmitted to said engine to start the engine in a state that said first and second clutch means are operated in the disconnected state and said second rotation regulating means is operated in the braking state, before said series type electric propulsion mode is started.

16. The power transmitting apparatus for a hybrid vehicle according to claim 15, wherein said second rotation regulating means comprises a one-way clutch for inhibiting only rotation of the first output shaft of said second power distributor in a predetermined one of the two rotating directions and forced braking means for inhibiting rotation of the first output shaft of said second power distributor via the actuator, and wherein when said engine is started before said series type electric propulsion mode is started, said second rotation regulating means is operated in the braking state using its one-way clutch, and in said series type electric propulsion mode, said second rotation regulating means is operated in the braking state using its forced braking means.

17. The power transmitting apparatus for a hybrid vehicle according to claim 14, wherein said series type electric propulsion mode and said speed change propulsion mode are shifted to each other via a transition mode, and the transition mode is a mode in which a rotation speed of said first motor and the torque generated by the second motor are set at almost zero, in which said first clutch means is operated in the connected state, with said first rotation regulating means operated in the open state, and in which an operational state of the second clutch means and second rotation regulating means is switched, and.

18. The power transmitting apparatus for a hybrid vehicle according to claim 14, wherein said engine has a plurality of cylinders, and said series type electric propulsion mode comprises a partial cylinder halt mode in which some of all the cylinders of the engine are halted.

19. The power transmitting apparatus for a hybrid vehicle according to claim 8, wherein said first clutch means is operated in the disconnected state, said second clutch means is operated in the connected state, said first rotation regulating means is operated in the braking state, said second rotation regulating means is operated in the open state, and the second motor is caused to generate the regenerative torque in a parallel type propulsion mode, and the parallel type propulsion mode is a mode in which the vehicle is propelled by transmitting the rotational drive power of said engine and the rotational drive power of said first motor to said power output shaft in parallel.

20. The power transmitting apparatus for a hybrid vehicle according to claim 8, comprising third rotation regulating means that can operate in a braking state in which rotation of a rotatable shaft of one of said first and second motors is inhibited which motor has the lower speed reduction ratio and which motor applies a torque to the second output shaft of the power distributor in the rotation transmitting system with the lower speed reduction ratio, and in an open state in which the rotatable shaft can be rotated, and wherein if said engine becomes inoperative while the vehicle is being propelled in said speed change propulsion mode, said third rotation regulating means is operated in the braking state.

21. The power transmitting apparatus for a hybrid vehicle according to claim 20, wherein said third rotation regulating means comprises a one-way clutch for hindering the rotatable shaft of said motor with the lower speed reduction ratio from rotating in an inverse direction while the vehicle is being propelled in said speed change propulsion mode.

22. The power transmitting apparatus for a hybrid vehicle according to claim 8, wherein at least one of said two rotation transmitting systems has a speed change unit that can change the speed reduction ratio for the rotation transmitting system at a plurality of levels, and the speed change unit changes the speed reduction ratio to establish a state in which the rotation transmitting system with said first power distributor has a higher speed reduction ratio than the rotation transmitting system with said second power distributor and a state in which the rotation transmitting system with said second power distributor has a higher speed reduction ratio than the rotation transmitting system with said first power distributor, and wherein the apparatus comprises third rotation regulating means that can operate in a braking state in which the rotatable shaft of said first motor is inhibited from rotating and in an open state in which the rotatable shaft is rotatable, and fourth rotation regulating means that can operate in a braking state in which the rotatable shaft of said second motor is inhibited from rotating and in an open state in which the rotatable shaft is rotatable, and wherein if said engine becomes inoperative while the vehicle is being propelled in said speed change propulsion mode in which the rotation transmitting system with said first power distributor has a higher speed reduction ratio than the rotation transmitting system with said second power distributor, said fourth rotation regulating means is operated in the braking state, and if said engine becomes inoperative while the vehicle is being propelled in said speed change propulsion mode in which the rotation transmitting system with said second power distributor has a higher speed reduction ratio than the rotation transmitting system with said first power distributor, said third rotation regulating means is operated in the braking state.

23. The power transmitting apparatus for a hybrid vehicle according to claim 22, wherein said third rotation regulating means comprises a first one-way clutch for hindering the first motor from rotating in an inverse direction while the vehicle is being propelled in said speed change propulsion mode and the rotation transmitting system with said first power distributor has a lower speed reduction ratio than the rotation transmitting system with said second power distributor, and first one-way clutch OFF means for stopping the rotation inhibiting function of the first one-way clutch while the vehicle is being propelled in said speed change propulsion mode in which the rotation transmitting system with said first power distributor has a higher speed reduction ratio than the rotation transmitting system with said second power distributor, and wherein said fourth rotation regulating means comprises a second one-way clutch for hindering the second motor from rotating in an opposite direction while the vehicle is being propelled in said speed change propulsion mode in which the rotation transmitting system with said second power distributor has a lower speed reduction ratio than the rotation transmitting system with said first power distributor, and second one-way clutch OFF means for stopping the rotation inhibiting function of the second one-way clutch while the vehicle is being propelled in said speed change propulsion mode in which the rotation transmitting system with said second power distributor has a higher speed reduction ratio than the rotation transmitting system with said first power distributor.

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Description

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BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a power transmitting apparatus for a hybrid vehicle comprising an engine, motors, and power distributors.

2. Description of the Related Art

For example, Japanese Patent Laid-Open No. 11-301291 discloses a known power transmitting apparatus for a hybrid vehicle comprising an engine, motors (electric motors), and power distributors. This hybrid vehicle comprises an engine, two motors, and power distributors (differential gear devices) each composed of two pinion gear devices. The rotational drive power of the engine is distributively inputted to an input shaft of each power distributor via a gear. One of two output shafts of each power distributor is coupled to one of the two motors so that a drive (motoring) or regenerative torque from the motor is applied to the power distributor. Rotative drive powers from the other output shafts of the power distributors are transmitted in parallel to one power output shaft connected to drive wheels of the vehicle. The speed reduction ratio for a rotation transmitting system from the engine to the power output shaft via one of the power distributors is different from the speed reduction ratio for a rotation transmitting system from the engine to the power output shaft via the other power distributor. Specifically, the speed reduction ratio for each rotation transmitting system is determined when one of the two output shafts of the power distributor in the rotation transmitting system which shaft is connected to the motor has a rotation speed of 0.

In the power transmitting apparatus for a hybrid vehicle configured as described above, one of the motors is brought into a driving (motoring) state, the other motor is brought into a regenerative (generating) state, and the motors are set to consume and generate almost equal amount of power. Then, in a steady state (a car speed is almost constant), for the rotation speed .omega.e and torque Te of the engine and the rotation speed .omega.v and torque Tv of the power output shaft, the relation Tv=(.omega.e/.omega.v)Te is established. Further, in this case, a speed reduction ratio (.omega.e/.omega.v) for the transmission of rotations from the engine to the power output shaft can be changed to an arbitrary value between the two speed reduction ratios of the rotating transmitting system by controlling the torque generated by each motor.

Accordingly, if the vehicle is propelled using the engine as a propulsion source, the speed reduction ratio (speed change ratio) for the transmission of rotations from the engine to the power output shaft can be continuously changed by controlling the torques generated by both motors. This provides functions comparable to those provided if a continuous speed change device such as a CVT is provided between the engine and the power output shaft. That is, the vehicle can be propelled using an output from the engine while changing the speed between the engine and the power output shaft and without the need for a mechanical continuous speed change device such as a CVT.

Furthermore, by causing a deviation in the state in which the power consumption of the motor in the driving state is almost equal to the power generation of the motor in the regenerative state, it is possible to use the motor to generate an assist drive power or to charge a battery that is a power source for the motor. Moreover, by allowing both motors to transmit torques to the power output shaft while controlling the torques of both motors so that the load torque on the engine is zero, the vehicle can be propelled using only the output from the motors (what is called EV propulsion) and without using the output from the engine.

To improve the energy efficiency of a hybrid vehicle of this kind, it is preferable to carry out EV propulsion of using only the output from the motors and without using the output from the engine, during, for example, cruise propulsion in which the vehicle speed is relatively low. This is because when the vehicle is propelled using the output from the engine in a low vehicle speed region, it is generally difficult to operate the engine at an operation point with a high energy efficiency. For the EV propulsion, it is preferable to properly charge the battery using the output from the engine in order to supplement the power of the battery, which is the power source of the motors. Specifically, during, for example, the cruise propulsion at a low vehicle speed, to improve the energy efficiency of the hybrid vehicle, it is preferable to carry out what is called series type EV propulsion in which the vehicle is propelled using the outputs from the motors, while properly utilizing the output from the engine to charge the battery.

However, in the hybrid vehicle disclosed in Japanese Patent Laid-Open No. 11-301291, while the engine is being operated, the output from the engine is always inputted to the power distributors. It is thus impossible to allow one of the motors to generate power using the output from the engine while propelling the vehicle using the drive power of the other motor, regardless (independently) of the propulsive state (desired propulsive torque and speed of the vehicle and the like) of the vehicle. That is, the series type EV propulsion cannot be carried out.

Further, with the invention described in Japanese Patent Laid-Open No. 11-301291, when the EV propulsion is carried out to propel the vehicle using the drive power of the motors and without using the output from the engine, the torques of both motors are transmitted to the power output shaft while offsetting the torque transmitted by each motor to the engine so that the load torque on the engine is zero. Thus, when carrying out the EV propulsion, each motor must generate a large torque. Consequently, it is likely that the capacity of each motor must be increased, and the power loss of each motor is likely to increase.

On the other hand, the applicant has proposed, in Japanese Patent Laid-Open No. 2002-52944, a hybrid vehicle comprising two power distributors and two motors which vehicle is capable of not only the speed change propulsion as in the case of Japanese Patent Laid-Open No. 11-301291 but also the series type EV propulsion or the like. The technique disclosed in Japanese Patent Laid-Open No. 2002-52944 comprises a rotation transmission path through which rotations are transmitted between one of the motors and the engine without using any power distributors and a rotation transmission path through which rotations are transmitted between the other motor and the power output shaft without using any power distributors. A clutch is provided in each of these rotation transmission paths and rotation transmission paths from the respective motors to the corresponding power distributors. Then, the proper combination of connections and disconnections of the clutches enables the vehicle to travel in various propulsive modes including the series type EV propulsion. However, the technique disclosed in Japanese Patent Laid-Open No. 2002-52944 requires more rotation transmission paths and clutches than that disclosed in Japanese Patent Laid-Open No. 11-301291, previously described. Consequently, with the technique disclosed in Japanese Patent Laid-Open No. 2002-52944, it is difficult to reduce the size of the while power transmitting apparatus.

Moreover, with the technique disclosed in Japanese Patent Laid-Open No. 11-301291, if the engine becomes inoperative (the engine does not generate any output) for any reason while carrying out change speed propulsion, then in particular the rotation speed of one of the motors which is connected to the power distributor in a system from the engine to the power output shaft which system has a higher speed reduction ratio for the transmission of rotations becomes high compared to the service rotation speed region during the normal speed change propulsion. Thus, the higher-speed-reduction-ratio motor is desired to endure a rotation speed (which does not occur during the normal propulsion) that is high compared to the service rotation speed region during the speed change propulsion. Further, a drive circuit for this motor must have a sufficiently large conduction capacity compared to the service region during the speed change propulsion. As a result, the sizes of the motors and its drive circuit must be increased, thus preventing miniaturization of the power transmitting apparatus.

In view of this background, it is an object of the present invention to provide a power transmitting apparatus that enables a small configuration to accomplish not only the speed change propulsion but also various other forms of propulsions such as the EV propulsion including the series type EV propulsion. It is another object of the present invention to provide a power transmitting apparatus that can use a simple configuration to prevent motors from rotating at excessively high speed even if an engine becomes inoperative during the speed change propulsion.

SUMMARY OF THE INVENTION

A power transmitting apparatus for a hybrid vehicle according to the present invention is obtained by improving a power transmitting apparatus for a hybrid vehicle comprising a first and second power distributors each having an input end to which a rotational drive power from an engine is transmitted, a power output shaft to which a first output shaft of two output shafts of the first power distributor and a first output shaft of two output shafts of the second power distributor transmit rotational drive powers and which output the transmitted rotational drive powers to drive wheels of the vehicle, a first motor that applies a drive torque or regenerative torque to a second output shaft of the first power distributor, and a second motor that applies a drive torque or regenerative torque to a second output shaft of the second power distributor, a speed reduction ratio for a rotation transmitting system from the engine to the power output shaft via the first power distributor having a value different from a value of a speed reduction ratio for a rotation transmitting system from the engine to the power output shaft via the second power distributor.

To accomplish the above object, a first aspect of the power transmitting apparatus according to the present invention is characterized in that the apparatus comprises first clutch means for connecting and disconnecting the engine to and from the input shaft of the first power distributor for rotation transmission, second clutch means for connecting and disconnecting the first output shaft of the second power distributor to and from the power output shaft for rotation transmission, first rotation regulating means operating in an open state in which the input shaft of the first power distributor is rotatable and in a braking state in which the input shaft is inhibited from rotating, and second rotation regulating means operating in an open state in which the first output shaft of the second power distributor is rotatable and in a braking state in which the first output shaft is inhibited from rotating.

According to the first aspect of the present invention, the first clutch means can block the transmission of rotations between the engine and the first power distributor or the transmission of torque between the engine and the first motor. Moreover, the first rotation regulating means can inhibit the rotation of the input shaft of the first power distributor. Accordingly, when the first clutch means is brought into a disconnected state, rotations (torques) can be transmitted between the first motor and the power output shaft. Further, the second clutch means can properly block the transmission of rotations between the first output shaft of the second power distributor and the power output shaft or the transmission of torque between the second motor and the power output shaft. Moreover, the second rotation regulating means can inhibit the rotation of the first output shaft of the second power distributor. Accordingly, when the second clutch means is brought into the disconnected state, rotations (torques) can be transmitted between the second motor and the engine. Further, although a description will be made later in detail, if for example, both first and second clutch means are brought into a connected state and the first and second rotation regulating means are brought into an open state, torques can be transmitted between the engine and the first motor and between the second motor and the power output shaft as in the case of conventional power transmitting apparatuses for hybrid vehicles. As a result, the first aspect of the present invention makes it possible to use a small configuration to carry out not only speed change propulsion but also various other forms of propulsions such as electric propulsion (EV propulsion) including series type electric propulsion without the need for a special rotation transmission path through which the series type electric propulsion can be carried out.

In the first aspect of the present invention, each of the first and second power distributors generally comprises a differential gear device, for example, a pinion gear device (second aspect). In this case, the input shaft, first output shaft, and second output shaft of each of the power distributors are a ring gear, a carrier, and a sun gear of the pinion gear device respectively constituting the power distributor (third aspect).

In the first to third aspects of the present invention, the first rotation regulating means preferably comprises a one-way clutch for inhibiting only rotation of the input shaft of the first power distributor in a predetermined one of two rotating directions (fourth aspect). Thus, when the rotation of the input shaft of the first power distributor in the predetermined direction is to be inhibited (if for example, a torque that rotates the power output shaft in a predetermined direction is transmitted from the first motor to the power output shaft while the first clutch means is in the disconnected state), the one-way clutch of the first rotation regulating means can inhibit the rotation of the input shaft of the first power distributor without using the actuator or controlling its operations. Further, the one-way clutch does not require any energy sources for its operations. Consequently, consumed energy can be saved.

In the fourth aspect of the present invention, preferably, the first rotation regulating means further comprises forced braking means for inhibiting rotation of the input shaft of the first power distributor via an actuator (fifth aspect). Thus, the forced braking means can inhibit the rotation of the input shaft of the first power distributor in the opposite direction with respect to the rotation inhibited by the one-way clutch of the first rotation regulating means.

In the first to fifth aspects of the present invention, the second rotation regulating means preferably comprises a one-way clutch for inhibiting only rotation of the first output shaft of the second power distributor in a predetermined one of two rotating directions (sixth invention). Thus, when the rotation of the first output shaft of the second power distributor in the predetermined direction is to be inhibited (if for example, a torque that starts the engine is transmitted from the second motor to the engine while the second clutch means is in the disconnected state), the one-way clutch of the second rotation regulating means can inhibit the rotation of the first output shaft of the second power distributor without using the actuator or controlling its operations. Further, the one-way clutch does not require any energy sources for its operations. Consequently, the consumed energy can be saved.

In the sixth aspect of the present invention, preferably, the second rotation regulating means further comprises forced braking means for inhibiting rotation of the first output shaft of the second power distributor via an actuator (seventh aspect). It is thus possible to inhibit the rotation of the first output shaft of the second power distributor in the opposite direction with respect to the rotation inhibited by the one-way clutch of the second rotation regulating means.

In the first to third aspects of the present invention, more specifically, various forms of vehicle propulsions such as the speed change propulsion, electric propulsion (EV propulsion) can be carried out by operating the clutch means and the rotation regulating means as described below.

That is, the first and second clutch means are operated in a connected state and the first and second rotation regulating means are operated in an open state in a speed change propulsion mode, and the speed change propulsion mode is a mode in which the vehicle is propelled by transmitting the rotational drive power of the engine to the power output shaft via the first and second power distributors while generating a drive torque in one of the first and second motors and a regenerative torque in the other and in which the torques generated by the first and second motors are controlled to control a speed change ratio between the engine to the power output shaft (eighth aspect). By thus operating the first and second clutch means and the first and second rotation regulating means, it is possible to transmit torques between the engine, the first and second motor, and the power output shaft. Consequently, the vehicle can be propelled in the speed change propulsion mode.

Additionally, in the speed change propulsion mode, the speed reduction ratio between the engine and the power output shaft can be arbitrarily changed between a value for the speed reduction ratio of the rotation transmitting system (hereinafter sometimes referred to as an engine-to-power-output-shaft first rotation transmitting system) from the engine to the power output shaft via the first power distributor and a value for the speed reduction ratio of the rotation transmitting system (hereinafter sometimes referred to as an engine-to-power-output-shaft second rotation transmitting system) from the engine to the power output shaft via the second power distributor.

In the eighth aspect of the present invention, the first and second clutch means are operates in a disconnected state and the first rotation regulating means operates in a braking state in an speed change propulsion mode, and the electric propulsion mode is a mode in which the drive torque of the first motor is transmitted to the power output shaft to start and propel the vehicle (ninth aspect).

Specifically, when the first and second clutch means are operated in the disconnected state and the first rotation regulating means is operated in the braking state, the transmission of rotations between the engine and the power output shaft is disabled. On the other hand, rotations can be transmitted between the first motor and the power output shaft via the first power distributor. Consequently, the output from the first motor can be used to allow the vehicle to carry out the electric propulsion (EV propulsion) by transmitting the drive torque of the first motor to the power output shaft via the first power distributor regardless of the operational state of the engine. In this case, the drive torque of the first motor is mechanically transmitted to the power output shaft via the power distributor to propel the vehicle. Therefore, the vehicle can be propelled while efficiently transmitting the drive torque of the first motor to the power output shaft. Further, the propulsive drive power of the vehicle can be manipulated simply by controlling the drive torque of the first motor. It is thus possible to easily control the propulsion of the vehicle in the electric propulsion mode.

In the ninth aspect of the present invention, a rotation transmitting system from the first motor to the power output shaft via the first power distributor has a higher speed reduction ratio than a rotation transmitting system from the second motor to the power output shaft via the second power distributor (tenth aspect).

According to the ninth aspect of the present invention, the motor generating a drive torque that allows the vehicle to travel in the electric propulsion mode is the first motor for the higher speed reduction ratio for the transmission of rotations from the motor to the power output shaft. This makes it possible to reduce the drive torque required for the first motor.

In the ninth or tenth aspect of the present invention, preferably, the first rotation regulating means comprises a one-way clutch for inhibiting only rotation of the input shaft of the first power distributor in a predetermined one of the two rotating directions and forced braking means for inhibiting rotation of the input shaft of the first power distributor via the actuator, and when the vehicle is propelled forward in the electric propulsion mode, the first motor is caused to generate a drive torque that advances the vehicle, while the first rotation regulating means is operated in the braking state using its one-way clutch, and when the vehicle is propelled backward in the electric propulsion mode, the first motor is caused to generate a drive torque in a direction inverse to that of the drive torque generated when the vehicle is propelled forward, while the first rotation regulating means is operated in the braking state using its forced braking means (eleventh aspect).

Thus, when the vehicle is propelled in the electric propulsion mode, during forward propulsion, which is more frequent than backward propulsion, the one-way clutch not requiring any energy sources for operations inhibits the input shaft of the first power distributor from rotating. During the backward movement, which is more infrequent than the forward movement, the forced braking means having the actuator inhibits the input shaft of the first power distributor from rotating. Thus, the first rotation regulating means uses only the minimum amount of energy. Further, the vehicle can be moved forward and backward in the electric propulsion mode by reversing the drive torque generated by the first motor or providing a rotation transmission path exclusively used for backward movement.

In the eleventh aspect of the present invention, preferably, the drive torque of the second motor is transmitted to the engine to start the engine in a state that the first and second clutch means are operated in the disconnected state and the second rotation regulating means is operated in the braking state, before the vehicle starts traveling backward in the electric propulsion mode (twelfth aspect).

Specifically, by operating the first and second clutch means in the disconnected state and operating the second rotation regulating means in the braking state, it is possible to transmit rotations (torques) between the engine and the second motor via the second power distributor regardless of the propulsive state of the vehicle or the operational state of the first motor. Accordingly, the engine can be started by transmitting the drive torque of the second motor to the engine. When the engine is started to start traveling the vehicle backward, the first rotation regulating means can operate using, as a power source (energy source), a hydraulic pump and the like operated using the output from the engine. As a result, it is possible to reliably provide an energy source for the forced braking means of the first rotation regulating means for inhibiting the input shaft of the first power distributor from rotating during the backward propulsion in the electric propulsion mode.

If the conduction through the second motor is blocked after the start of the engine to zero the torque generated by the second motor, the engine becomes idle. In this idle state, the braking state of the second rotation regulating means may be released to bring the means into the open state.

In the twelfth aspect of the present invention, preferably, the second rotation regulating means comprises a one-way clutch for inhibiting only rotation of the first output shaft of the second power distributor in a predetermined one of the two rotating directions, when the engine is started before the vehicle starts traveling backward, the second rotation regulating means is operated in the braking state using its one-way clutch (thirteenth aspect). Thus, when the engine is started, the second rotation regulating means can reliably inhibit the rotation of the first output shaft of the second power distributor using the one-way clutch not requiring any energy sources for operations such as engine outputs.

In the ninth to eleventh embodiments, comprising the electric propulsion mode, the electric propulsion mode includes a series type electric propulsion mode in which the rotational drive power of the engine is transmitted to the second motor to allow the second motor to generate a regenerative power. In the series type electric propulsion mode, the second rotation regulating means is operated in the braking state (fourteenth aspect).

Specifically, by operating each clutch means and the first rotation regulating means as described above in the electric propulsion mode and operating the second rotation regulating means in the braking state, it is possible to transmit rotations (torques) between the engine and the second motor via the second power distributor regardless of the propulsive state of the vehicle or the operational state of the first motor as in the case of the start of the engine in the twelfth aspect of the present invention. Accordingly, regeneration for the second motor (charging of a battery that is a power source for the motors) can be executed using the rotational drive power of the engine (output torque from the engine) transmitted to the second motor via the second power distributor, while the vehicle is undergoing the electric propulsion using the output from the first motor. That is, the series type electric propulsion (EV propulsion) can be carried out. In this case, the second motor can execute the regeneration using the rotational drive power of the engine transmitted to the second motor, regardless of the propulsive state of the vehicle. Consequently, it is possible to efficiently regenerate power for the second motor while operating the engine at an operational point with the highest energy efficiency. As a result, the energy required for the vehicle can be effectively saved.

In the fourteenth aspect of the present invention, the drive torque of the second motor is transmitted to the engine to start the engine in a state that the first and second clutch means are operated in the disconnected state and the second rotation regulating means is operated in the braking state, before the series type electric propulsion mode is started (fifteenth aspect).

Thus, as in the case of the twelfth aspect of the present invention, the second motor transmits a torque to the engine to start it. In this case, the first and second clutch means are brought into the disconnected state as in the case of the electric propulsion mode. Furthermore, while the clutch means is in the disconnected state, the transmission of rotations between the first motor and the power output shaft is independent of the transmission of rotations between the engine and the second motor. Consequently, while the electric propulsion is being carried out using the first motor, the engine can be smoothly started by the second motor without affecting the propulsive state. Moreover, the operational state of the second rotation regulating means observed when the engine is started is the same as the operational state of the second rotation regulating means observed during the series type electric propulsion (braking state). Therefore, the series type electric propulsion, in which the regeneration for the second motor is executed, can be started smoothly and promptly after the engine has been started.

In the fifth aspect of the present invention, preferably, the second rotation regulating means comprises a one-way clutch for inhibiting only rotation of the first output shaft of the first power distributor in a predetermined one of the two rotating directions and forced braking means for inhibiting rotation of the first output shaft of the second power distributor via the actuator, and when the engine is started before the series type electric propulsion mode is started, the second rotation regulating means is operated in the braking state using its one-way clutch, and in the series type electric propulsion mode, the second rotation regulating means is operated in the braking state using its forced braking means (sixteenth aspect).

Specifically, the direction of the torque acting on the first output shaft of the second power distributor when the engine is started by transmitting a torque from the second motor to the engine via the second power distributor is opposite to the direction of the torque acting on the first output shaft of the second power distributor when the regeneration for the second motor is executed using a torque transmitted from the engine to the second motor via the second power distributor. In this case, when the engine is started, the one-way clutch of the second rotation regulating means inhibits the rotation of the first output shaft of the second power distributor. This makes it possible to reliably inhibit the rotation of the first output shaft of the second power distributor without the necessity of an energy source for operation such as engine output. Further, the energy consumed by the vehicle can be saved. Then, in the series type electric propulsion mode after the start of the engine, the forced braking means, which requires an energy source for operations, inhibits the rotation of the first output shaft of the second power distributor. However, in this case, the forced braking means can be reliably operated using, as a power source (energy source), for example, a hydraulic pump operated using the output from the engine.

In the fourteenth to sixteenth aspects of the present invention, wherein the series type electric propulsion mode and the speed change propulsion mode are shifted to each other via the transition mode, and the transition mode is a mode in which a rotation speed of the first motor and the torque generated by the second motor are set at almost zero, in which the first clutch means is operated in the connected state, with the first rotation regulating means operated in the open state, and in which an operational state of the second clutch means and second rotation regulating means is switched, and (seventeenth aspect).

In the series type electric propulsion mode, both first and second clutch means are in the disconnected state, and both first and second rotation regulating means are in the braking state. In contrast, in the speed change propulsion mode, both first and second clutch means are in the connected state, and both first and second rotation regulating means are in the open state. Accordingly, when the mode is switched between the series type electric propulsion and the speed change propulsion, each of the clutch means and rotation regulating means must be switched to a different operational state. Then, when the operational state of each of these means is switched simultaneously, the propulsive behavior of the vehicle temporarily becomes awkward.

Thus, in the seventeenth aspect of the present invention, when the mode is switched between the series type electric propulsion and the speed change propulsion, the transition mode is interposed between these modes. In the transition mode, the rotation speed of the first motor and the torque generated by the second motor are set at almost zero, the first clutch means is operated in the connected state, with the first rotation regulating means operated in the open state. Accordingly, the engine transmits almost all of the rotational drive power (output torque) to the power output shaft via the input shaft and first output shaft of the first power distributor. In this state, the engine transmits little rotational drive power to the second power distributor. Consequently, even if the operational state of the second rotation regulating means and second clutch means of the second power distributor is changed, the propulsive state of the vehicle is not affected. Therefore, the operational state of the second rotation regulating means and second clutch means can be switched in the transition mode without affecting the propulsive state of the vehicle. The transmission of the rotational drive power (torque) from the engine to the power output shaft in the transition mode is comparable to the state established by the speed change control in which the speed reduction ratio for the transmission of rotations from the engine to the power output shaft is equal to the speed reduction ratio for the engine-to-power-output-shaft first rotation transmitting system. It is possible to smoothly carry out the shifting between the speed change propulsion mode and the transition mode. Then, the operational state of the first clutch means and first rotation regulating means is switched between the transition mode and the series type electric propulsion mode. In this case, between the transition mode and the series type electric propulsion mode, the path through which a torque is transmitted to the power output shaft only shifts between a transmission path from the engine and the transmission path from the first motor. Accordingly, by gradually switching the operational state of the first clutch means and first rotation regulating means while performing the throttle control of the engine (opening control a throttle valve in an inlet system) and the torque control of each motor, it is possible to smoothly switch between the transition mode and the series type electric propulsion mode while maintaining the propulsive state of the vehicle. Therefore, by interposing the transition mode between the series type electric propulsion mode and the speed change propulsion mode, it is possible to smoothly shift between these modes.

Basically, it is sufficient to execute the speed change propulsion mode only when the vehicle is propelled forward. Then, if the first rotation regulating means comprises a one-way clutch inhibiting the input shaft of the first power distributor from rotating during the forward propulsion in the electric propulsion mode as in the case of the eleventh aspect of the present invention, the one-way clutch can be used to automatically switch the operational state of the first rotation regulating means between the transition mode and the series type electric propulsion mode without the need for the special control of the first rotation regulating means.

In the fourteenth to seventeenth aspects of the present invention, comprising the series type electric propulsion mode as previously described, when the engine has a plurality of cylinders, the series type electric propulsion mode preferably comprises a partial cylinder halt mode in which some of all the cylinders of the engine are halted (eighteenth aspect).

That is, the engine has what is called a pumping loss. However, by executing the partial cylinder halt mode to halt some of the cylinders of the engine when, for example, the desired output of the engine is relatively low, it is possible to reduce the pumping loss of the engine and thus its energy consumption. In this case, the partial cylinder halt mode is executed during the series type electric propulsion mode, in which the rotational drive power of the engine is not transmitted to the power output shaft. Accordingly, halting some cylinders of the engine does not affect the propulsive state of the vehicle. Consequently, the eighteenth aspect of the present invention makes it possible to improve the energy efficiency of the vehicle without affecting the propulsive state of the vehicle. More specifically, some cylinders can be halted by stopping the supply of a fuel to those cylinders, while keeping the intake and exhaust valves of the cylinders fully open or closed.

In the eighth to eighteenth aspects of the present invention, preferably, the first clutch means is operated in the disconnected state, the second clutch means is operated in the connected state, the first rotation regulating means is operated in the braking state, the second rotation regulating means is operated in the open state, and the second motor is caused to generate the regenerative torque in a parallel type propulsion mode, and the parallel type propulsion mode is a mode in which the vehicle is propelled by transmitting the rotational drive power of the engine and the rotational drive power of the first motor to the power output shaft in parallel, and in the parallel type propulsion mode, (nineteenth aspect).

Specifically, by operating the first clutch means in the disconnected state and the first rotation regulating means in the braking state, it is possible to transmit the drive torque of the first motor to the power output shaft via the first power distributor as in the case of the electric propulsion mode. Moreover, the rotational drive power of the engine (output torque of the engine) can be transmitted to the power output shaft via the second power distributor by operating the second clutch means in the connected state and the second rotation regulating means in the open state and allowing the second motor to generate a regenerative torque. Consequently, the drive torque of the first motor and the rotational drive power of the engine can be transmitted to the power output shaft in parallel. As a result, the propulsive drive power of the vehicle can be improved.

In the eighth to nineteenth aspects of the present invention, comprising the speed change propulsion mode, preferably, the apparatus comprises third rotation regulating means that can operate in a braking state in which rotation of a rotatable shaft of one of the first and second motors is inhibited which motor has the lower speed reduction ratio and which applies a torque to the second output shaft of the power distributor in the rotation transmitting system with the lower speed reduction ratio, and in an open state in which the rotatable shaft can be rotated, and if the engine becomes inoperative while the vehicle is being propelled in the speed change propulsion mode, the third rotation regulating means is operated in the braking state (twentieth aspect). When the engine is inoperative, the engine cannot generate any outputs owing to the inappropriate supply of a fuel to the engine or the like.

In the twentieth aspect of the present invention, if the engine becomes inoperative while the vehicle is being propelled in the speed change propulsion mode, the third rotation regulating means inhibits the rotation of a rotatable shaft of one of the first and second motors which motor has the lower speed reduction ratio and which motor applies a torque to the second output shaft of the power distributor in the rotation transmitting system (engine-to-power-output-shaft first rotation transmitting system or engine-to-power-output-shaft second rotation transmitting system). Thus, the rotation speed of (output shaft of) the engine does not decrease below a value dependent on the vehicle speed. This prevents the excessively high rotation of the rotatable shaft of the motor (different from the one with the lower speed reduction ratio (one with the higher speed reduction ratio)) which applies a torque to the second output shaft of the power distributor in the rotation transmitting system with the higher speed reduction ratio. Consequently, the twentieth aspect of the present invention can prevent the rotation speed of the motor from increasing excessively even if the engine becomes inoperative during the speed change propulsion. Further, the capacities of each motor and its drive circuits can be limited to the minimum required values. This enables the power transmitting apparatus to be miniaturized.

In the twentieth aspect of the present invention, the third rotation regulating means suitably comprises a one-way clutch from hindering the rotatable shaft of the motor with the lower speed reduction ratio from rotating in an inverse direction while the vehicle is being propelled in the speed change propulsion mode (twenty-first aspect).

Assuming that the third rotation regulating means is not supplied, when the engine becomes inoperative while the vehicle is being propelled in the speed change propulsion mode, the rotation speed of the engine decreases to zero. However, at this time, the rotating direction of the rotatable shaft of the motor with the lower speed reduction ratio is opposite to that during the propulsion in the speed change propulsion mode. In other words, the rotating direction of the rotatable shaft of the motor with the lower speed reduction ratio is reversed to reduce the rotation speed of the engine down to zero. Thus, in the twenty-first aspect of the present invention, the one-way clutch inhibits the reversal of the rotatable shaft of the motor with the lower speed reduction ratio. The simple configuration based on the one-way clutch makes it possible to inhibit the rotation (reversal) of the rotatable shaft of the motor with the lower speed reduction ratio when the engine is inoperative. Further, in this case, the one-way clutch need not be controlled. Accordingly, when the engine becomes inoperative to cause the rotatable shaft of the motor with the lower speed reduction ratio to start rotating in the direction opposite to the one during the propulsion in the speed change propulsive mode, the one-way clutch automatically inhibits the rotation (reversal) of the rotatable shaft of the motor with the lower speed reduction ratio without a delay. It is thus possible to reliably prevent the rotatable shaft of the motor with the higher speed reduction ratio-from rotating at high speed.

In the eighth aspect of the present invention, comprising the speed change propulsion mode, if the power transmitting apparatus is configured so that the speed reduction ratio for each of the rotation transmitting systems (engine-to-power-output-shaft first or second rotation transmitting system) has a constant (fixed) value, the vehicle can carry out the speed change propulsion only in the speed variable range (possible range of the speed reduction ratio between the engine and the power output shaft) between the two speed reduction ratios. On the other hand, the vehicle can be propelled in various types of speed change ranges by providing a speed change unit in at least one of the two rotation transmitting systems to change the speed reduction ratio for the rotation transmitting system. In this case, basically, it is preferable to avoid superimposing the speed reduction regions on one another in order to improve the energy efficiency of the power transmitting apparatus. In this case, in the power transmitting apparatus, the speed change unit changes the speed reduction ratio to establish a state in which the rotation transmitting system with the first power distributor (engine-to-power-output-shaft first rotation transmitting system) has a higher speed reduction ratio than the rotation transmitting system with the second power distributor (engine-to-power-output-shaft second rotation transmitting system) and a state in which the rotation transmitting system with the second power distributor (engine-to-power-output-shaft second rotation transmitting system) has a higher speed reduction ratio than the rotation transmitting system with the first power distributor (engine-to-power-output-shaft first rotation transmitting system). Preferably, the power transmitting apparatus thus having the speed change unit comprises third rotation regulat