Patent Description:
<CIT> discloses a hybrid vehicle in which a dual-clutch transmission equipped with two clutches is mounted.

The above type of dual-clutch transmission includes an input system, an output system, and a plurality of gear trains. The input system includes a first input shaft connected to an internal combustion engine through a first clutch and a second input shaft connected to the internal combustion engine through a second clutch. The output system is connected to driven wheels of the vehicle and works to achieve transmission of drive power between itself and the driven wheels. Some of the gear trains are disposed between the first input shaft and the output system, while the other gear trains are arranged between the second input shaft and the output system. The gear trains are designed to have gear ratios different from each other.

The dual-clutch transmission includes a first motor generator and a second motor generator. The first motor generator is connected to the first input shaft so that drive power is transmittable therebetween. The second motor generator is connected to the second input shaft so that drive power is transmittable therebetween. The dual-clutch transmission works to selectively execute an engine-drive mode and a motor-drive mode. The engine-drive mode is to switch one of the first and second clutches to an engaged state to operate the driven wheels of the vehicle using the internal combustion engine. The motor-drive mode is to stop the internal combustion engine and operate the driven wheels using a corresponding one of the first and second motor generators.

The above described dual-clutch transmission, however, has a drawback in that two clutch sets each of which includes a clutch disc, a clutch cover, and a flywheel (i.e., the first and second clutches) are needed, thereby resulting in increases in size and production cost of the transmission.

Other examples of background art can be found in <CIT>, and <CIT>.

The present invention was mode in view of the above problem. It is an object of the invention to provide a hybrid vehicle which is capable of smoothly changing gears of a transmission without use of a plurality of clutches and enables the transmission to be reduced in size and production cost thereof.

According to one aspect of the invention, there is provided a hybrid vehicle which is equipped with a transmission working to transmit drive power produced by an internal combustion engine to a driven wheel and change a speed of the drive power. The transmission comprises: (a) an input shaft to which the drive power produced by the internal combustion engine is transmitted; (b) a first intermediate shaft which is arranged coaxially with the input shaft and rotatable relative to the input shaft the first intermediate shaft having the input shaft extending inside the first intermediate shaft;.

The above structure is capable of smoothly changing the gears of the transmission without use of a plurality of clutches and enables the transmission to be reduced in size and production cost thereof.

A hybrid vehicle according to an embodiment of the invention is equipped with a transmission working to transmit drive power produced by an internal combustion engine to a driven wheel and change a speed of the drive power. The transmission comprises: (a) an input shaft to which the drive power produced by the internal combustion engine is transmitted; (b) a first intermediate shaft which is arranged coaxially with the input shaft and rotatable relative to the input shaft, (c) a second intermediate shaft which is arranged coaxially with the input shaft, aligned with the first intermediate shaft in an axial direction of the input shaft, and rotatable relative to the input shaft; (d) an output shaft which extends parallel to the first intermediate shaft and the second intermediate shaft and serves to deliver the drive power to the driven wheel; (e) a first rotating electrical machine which is connected to the first intermediate shaft to transmit drive power therebetween, (f) a second rotating electrical machine which is connected to the second intermediate shaft to transmit drive power therebetween, (g) first gear sets each of which works to connect the first intermediate shaft with the output shaft to transmit drive power therebetween and which establish a plurality of gears in the transmission which are different in gear ratio from each other; (h) second gear sets each of which works to connect the second intermediate shaft with the output shaft to transmit drive power therebetween and which establish a plurality of gears in the transmission which are different in gear ratio than those of the first gear sets; and (i) a first switching member which works to switch among a neutral position, a first position, and a second position. The first position is to achieve connection of the input shaft and the first intermediate shaft. The second position is to achieve connection of the input shaft and the second intermediate shaft.

The above structure of the transmission mounted in the hybrid vehicle ensures a smooth gear change in the transmission without use of a plurality of clutches and enables the transmission to be reduced in size and produced at a decreased cost.

The hybrid vehicle <NUM> according to an embodiment of the invention will be described below with reference to the drawings. <FIG> are views which illustrate the hybrid vehicle <NUM> according to the embodiment of the invention.

The structure of the hybrid vehicle <NUM> will first be described below.

The hybrid vehicle <NUM> (which will also be merely referred to as a vehicle), as illustrated in <FIG>, includes the engine <NUM> implemented by an internal combustion engine, the transmission <NUM>, the driven wheels <NUM> and 4R, the HCU (Hybrid Control Unit) <NUM> working to totally control an operation of the vehicle <NUM>, the ECU (Engine Control Unit) <NUM> working to control an operation of the engine <NUM>, the TCU (Transmission Control Unit) <NUM> working to control an operation of the transmission <NUM>, the BMS (Battery Management System) <NUM>, the odd-numbered gear inverter <NUM>, the even-numbered gear inverter <NUM>, and the storage battery <NUM>.

The engine <NUM> is equipped with a plurality of cylinders. In this embodiment, the engine <NUM> is designed to perform a sequence of four stroke: intake, compression, expansion (also called combustion or power), and exhaust strokes of a piston in each cylinder.

The transmission <NUM> works to change gears (i.e., gear ratios) thereof to change the degree of drive power or torque, as inputted from the engine <NUM>, to deliver it to the left and right driven wheels <NUM> and 4R through the left and right drive shafts <NUM> and 31R, thereby driving the driven wheels <NUM> and 4R.

The transmission <NUM> includes the gear shifting mechanism <NUM>, the differential <NUM>, the odd-numbered gear motor generator <NUM>, the even-numbered gear motor generator <NUM>, and the actuator <NUM>.

The transmission <NUM> is designed as a so-called AMT (Automated Manual Transmission) and works to change the gears thereof using the actuator <NUM> controlled by the TCU <NUM>.

The differential <NUM> delivers drive power, as outputted from the gear shifting mechanism <NUM>, to the driven wheels <NUM> and 4R through the drive shafts <NUM> and 31R.

The gear shifting mechanism <NUM>, as illustrated in <FIG>, includes the input shaft <NUM>, the hollow cylindrical odd-numbered gear intermediate shaft <NUM>, the hollow cylindrical even-numbered gear intermediate shaft <NUM>, and the output shaft <NUM>. The input shaft <NUM>, the odd-numbered gear intermediate shaft <NUM>, the even-numbered gear intermediate shaft <NUM>, and the output shaft <NUM> are oriented to extend in the width-wise direction of the vehicle <NUM>. In the following discussion, a direction in which the vehicle <NUM> heads will also be referred to as a longitudinal direction. The width-wise direction of the vehicle <NUM> will also be referred to as a lateral direction.

The odd-numbered gear intermediate shaft <NUM> will also be referred to as a first intermediate shaft. The even-numbered gear intermediate shaft <NUM> will also be referred to as a second intermediate shaft.

The input shaft <NUM> is connected to the crankshaft <NUM> of the engine <NUM> through the coupling <NUM> made of a damper, so that drive power (i.e., engine torque), as produced by the engine <NUM>, is transmitted to the input shaft <NUM> through the coupling <NUM>. The coupling <NUM> connects the crankshaft <NUM> and the input shaft <NUM> together at all times so that the drive power is transmittable between the crankshaft <NUM> and the input shaft <NUM>.

When the vehicle <NUM> is accelerating, the coupling <NUM> works to absorb a variation in torque or rotation transmitted from the crankshaft <NUM> of the engine <NUM> to the input shaft <NUM>, while when the vehicle <NUM> is decelerating, the coupling <NUM> works to absorb a variation in torque or rotation transmitted from the input shaft <NUM> to the engine <NUM>.

The odd-numbered gear intermediate shaft <NUM> is arranged outside the input shaft <NUM> to be coaxial with the input shaft <NUM> and rotatable relative to the input shaft <NUM>. Specifically, the odd-numbered gear intermediate shaft <NUM> is hollow cylindrical to have the input shaft <NUM> disposed therein and retained by the input shaft <NUM> to be rotatable relative to the input shaft <NUM>.

The even-numbered gear intermediate shaft <NUM> is arranged outside the input shaft <NUM> to be coaxial with the input shaft <NUM> and rotatable relative to the input shaft <NUM>. Specifically, the even-numbered gear intermediate shaft <NUM> is hollow cylindrical to have the input shaft <NUM> disposed therein and retained by the input shaft <NUM> rotatably relative to the input shaft <NUM>.

The even-numbered gear intermediate shaft <NUM> is aligned with the odd-numbered gear intermediate shaft <NUM> in an axial direction of the input shaft <NUM> and located farther away from the engine <NUM> than the odd-numbered gear intermediate shaft <NUM> is. In other words, the engine <NUM>, the odd-numbered gear intermediate shaft <NUM>, and the even-numbered gear intermediate shaft <NUM> are arranged in this order from the left side of the input shaft <NUM>.

The input shaft <NUM>, the odd-numbered gear intermediate shaft <NUM>, and the even-numbered gear intermediate shaft <NUM> are arranged coaxially with each other and extend parallel to each other. In other words, the input shaft <NUM>, the odd-numbered gear intermediate shaft <NUM>, and the even-numbered gear intermediate shaft <NUM> are oriented to have a common rotational center axis.

The output shaft <NUM> is arranged to extend parallel to the odd-numbered gear intermediate shaft <NUM> and the even-numbered gear intermediate shaft <NUM>. The output shaft <NUM> extends to have a left end located more left than a left end of the odd-numbered gear intermediate shaft <NUM> is. The output shaft <NUM> also has a right end located more right than a right end of the even-numbered gear intermediate shaft <NUM>.

The odd-numbered gear intermediate shat <NUM> and the output shaft <NUM> are configured to achieve transmission of drive power therebetween through each of the first speed gear set <NUM> and the third speed gear set <NUM>. Specifically, each of the first speed gear set <NUM> and the third speed gear set <NUM> is configured to connect between the odd-numbered gear intermediate shat <NUM> and the output shaft <NUM> to transmit the drive power from the odd-numbered gear intermediate shat <NUM> to the output shaft <NUM> or from the output shaft <NUM> to the odd-numbered gear intermediate shat <NUM>. Each of the first speed gear set <NUM> and the third speed gear set <NUM> constitutes a first gear set working to establish a plurality of odd-numbered gears different in gear ratio from each other in the transmission <NUM>.

The first speed gear set <NUM> includes the first speed input gear 45A and the first speed output gear 45B. The first speed input gear 45A is rotatable together with the odd-numbered gear intermediate shaft <NUM>. The first speed output gear 45B is rotatable relative to the output shaft <NUM> and meshes with the first speed input gear 45A. The third speed gear set <NUM> includes the third speed input gear 47A and the third speed output gear 47B. The third speed input gear 47A is rotatable together with the odd-numbered intermediate shaft <NUM>. The third speed output gear 47B is rotatable relative to the output shaft <NUM> and meshes with the third speed input gear 47A. The first gear sets, as apparent from the above discussion, include the first speed input gear 45A and the third speed input gear 47A which are rotatable together with the odd-numbered gear intermediate shaft <NUM>. The first gear sets also include the first speed output gear 45B and the third speed output gear 47B which are rotatable relative to the output shaft <NUM> and mesh with the first speed input gear 45A and the third speed input gear 47A, respectively.

The odd-numbered gear intermediate shaft <NUM> has mounted thereon the odd-numbered motor-driven gear 50B which is larger in diameter than the third speed input gear 47A. The third speed input gear 47A is larger in diameter than the first speed input gear 45A.

The output shaft 23A of the odd-numbered gear motor generator <NUM> has the odd-numbered motor-drive gear 50A mounted thereon. The odd-numbered motor-drive gear 50A meshes with the odd-numbered motor-driven gear 50B.

The odd-numbered motor-drive gear 50A and the odd-numbered motor-driven gear 50B in this embodiment constitute a first rotating electrical machine gear set. The odd-numbered motor-drive gear 50A constitutes a first drive gear. The odd-numbered motor-driven gear 50B constitutes a first driven gear.

The drive power, as produced by the odd-numbered gear motor generator <NUM>, is transmitted from the odd-numbered motor-drive gear 50A to the odd-numbered gear intermediate shaft <NUM> through the odd-numbered motor-driven gear 50B. The odd-numbered gear motor generator <NUM> is located on the left side of the odd-numbered motor-drive gear 50A in an axial direction of the input shaft <NUM>. In other words, the odd-numbered gear motor generator <NUM> is located at substantially the same position as that of the first speed input gear 45A or the third speed input gear 47A as defined in the axial direction of the input shaft <NUM>.

The odd-numbered motor-drive gear 50A is smaller in diameter than the odd-numbered motor-driven gear 50B. The drive power or speed of rotation from the odd-numbered gear motor generator <NUM> to the odd-numbered gear intermediate shaft <NUM> is reduced by the odd-numbered motor-drive gear 50A and the odd-numbered motor-driven gear <NUM>.

The first speed output gear 45B is larger in diameter than the first speed input gear 45A. The third speed output gear 47B is smaller in diameter than the third speed input gear 47A.

The drive power is transmittable between the even-numbered gear intermediate shaft <NUM> and the output shaft <NUM> using the second speed gear set <NUM> or the fourth speed gear set <NUM>. In other words, the even-numbered gear intermediate shaft <NUM> and the output shaft <NUM> are connectable together so that each of the second speed gear set <NUM> and the fourth speed gear set <NUM> works to deliver the drive power from the even-numbered gear intermediate shaft <NUM> to the output shaft <NUM> or from the output shaft <NUM> to the even-numbered gear intermediate shaft <NUM>. The second speed gear set <NUM> and the fourth speed gear set <NUM> serve as second gear sets which establish a plurality of even-numbered gears different in gear ratio from each other in the transmission <NUM>.

The second speed gear set <NUM> includes the second speed input gear 46A and the second speed output gear 46B. The second speed input gear 46A is rotatable together with the even-numbered gear intermediate shaft <NUM>. The second speed output gear 46B is rotatable relative to the output shaft <NUM> and meshes with the second speed input gear 46A. The fourth speed gear set <NUM> includes the fourth speed input gear 48A and the fourth speed output gear 48B. The fourth speed input gear 48A is rotatable together with the even-numbered intermediate shaft <NUM>. The fourth speed output gear 48B is rotatable relative to the output shaft <NUM> and meshes with the fourth speed input gear 48A. The second gear sets, as apparent from the above discussion, include the second speed input gear 46A and the fourth speed input gear 48A which are rotatable together with the even-numbered gear intermediate shaft <NUM>. The second gear sets also include the second speed output gear 46B and the fourth speed output gear 48B which are rotatable relative to the output shaft <NUM> and mesh with the second speed input gear 46A and the fourth speed input gear 48A, respectively.

The even-numbered gear intermediate shaft <NUM> has the even-numbered motor-driven gear 51B mounted thereon. The even-numbered motor-driven gear 51B is larger in diameter than the fourth speed input gear 48A. The fourth speed input gear 48A is larger in diameter than the second speed input gear 46A.

The even-numbered gear motor generator <NUM> has the output shaft 24A on which the even-numbered motor-drive gear 51A is mounted. The even-numbered motor-drive gear 51A meshes with the even-numbered motor-driven gear 51B.

The even-numbered gear motor generator <NUM> is located on the right side of the even-numbered motor-drive gear 51A in the axial direction of the input shaft <NUM>. In other words, the even-numbered gear motor generator <NUM> is located at substantially the same position as that of the fourth speed input gear 48A or the second speed input gear 46A, as defined in the axial direction of the input shaft <NUM>.

The even-numbered motor-drive gear 51A and the even-numbered motor-driven gear 51B in this embodiment serve as a second rotating electrical machine gear set. The even-numbered motor-drive gear 51A constitutes a second drive gear. The even-numbered motor-driven gear 51B constitutes a second driven gear.

The even-numbered motor-drive gear 51A is smaller in diameter than the even-numbered motor-driven gear 51B. The drive power or speed of rotation from the even-numbered gear motor generator <NUM> to the even-numbered gear intermediate shaft <NUM> is reduced by the even-numbered motor-drive gear 51A or the even-numbered motor-driven gear 51B.

The second speed output gear 46B is larger in diameter than the second speed input gear 46A. The fourth speed output gear 48B is smaller in diameter than the fourth speed input gear 48A.

The input gears: the first speed input gear 45A, the second speed input gear 46A, the third speed input gear 47A, and the fourth speed input gear 48A have diameters increasing in this order. The output gears: the first speed output gear 45B, the second speed output gear 46B, the third speed output gear 47B, the fourth speed output gear 48B have diameters decreasing in this order.

With the above gear arrangements, the gear ratio of the first gear of the transmission <NUM> is larger than those of the second, third, and fourth gears of the transmission <NUM>. The second, third, and fourth gears have gear ratios which become smaller in this order. The transmission <NUM>, therefore, has four forward gears, but however, the number of gears thereof may be optional.

The first speed input gear 45A and the third speed input gear 47A work as first intermediate shaft gears. The first speed output gear 45B and the third speed output gear 47B work as first output shaft gears. The second speed input gear 46A and the fourth speed input gear 48A work as second intermediate shaft gears. The second speed output gear 46B and the fourth speed output gear 48B work as second output shaft gears.

The input shaft <NUM> has the rings-shaped first dog-clutch <NUM> mounted thereon. The first dog-clutch <NUM> is arranged between the odd-numbered gear intermediate shaft <NUM> and the even-numbered gear intermediate shaft <NUM> in the axial direction of the input shaft <NUM>. The first dog-clutch <NUM> is movable in the axial direction of the input shaft <NUM> and rotatable along with the input shaft <NUM>.

The first dog-clutch <NUM> has a plurality of dog teeth 52A arranged on a left end thereof and a plurality of dog teeth 52B arranged on a right end thereof.

The odd-numbered gear intermediate shaft <NUM> has a right end which faces the first dog-clutch <NUM> and on which a plurality of dog teeth 42A are formed. Similarly, the even-numbered gear intermediate shaft <NUM> has a left end which faces the first dog-clutch <NUM> and on which a plurality of dog teeth 43A are formed.

The first dog-clutch <NUM> is moved by the actuator <NUM> in the axial direction of the input shaft <NUM>.

When the first dog-clutch <NUM> is moved by the actuator <NUM> from a neutral position thereof toward the odd-numbered gear intermediate shaft <NUM> and reaches an odd-numbered gear position where the dog teeth 52A mesh with the dog teeth 42A of the odd-numbered gear intermediate shaft <NUM>, it causes the input shaft <NUM> to connect with the odd-numbered gear intermediate shaft <NUM> through the first dog-clutch <NUM>.

The above connection between the input shaft <NUM> and the odd-numbered gear intermediate shaft <NUM> causes the input shaft <NUM> to rotate along with the odd-numbered gear intermediate shaft <NUM>, thereby delivering the drive power, as produced by the engine <NUM>, from the input shaft <NUM> to the odd-numbered gear intermediate shaft <NUM>. The odd-numbered gear position, as referred to in this embodiment, will also be referred to as a first position.

When the first dog-clutch <NUM> is moved by the actuator <NUM> from a neutral position thereof toward the even-numbered gear intermediate shaft <NUM> and reaches an even-numbered gear position where the dog teeth 52B mesh with the dog teeth 43A of the even-numbered gear intermediate shaft <NUM>, it causes the input shaft <NUM> to connect with the even-numbered gear intermediate shaft <NUM> through the first dog-clutch <NUM>.

The above connection between the input shaft <NUM> and the even-numbered gear intermediate shaft <NUM> causes the input shaft <NUM> to rotate along with the even-numbered gear intermediate shaft <NUM>, thereby delivering the drive power, as produced by the engine <NUM>, from the input shaft <NUM> to the even-numbered gear intermediate shaft <NUM>. The even-numbered gear position, as referred to in this embodiment, will also be referred to as a second position.

When the first dog-clutch <NUM> is at the neutral position where it is placed out of engagement with the odd-numbered gear intermediate shaft <NUM> or the even-numbered gear intermediate shaft <NUM>, it causes the input shaft <NUM>, the odd-numbered gear intermediate shaft <NUM>, and the even-numbered gear intermediate shaft <NUM> to rotate relative to each other, so that the drive power, as produced by the engine <NUM>, is not transmitted to the odd-numbered gear intermediate shaft <NUM> and the even-numbered gear intermediate shaft <NUM>.

The odd-numbered motor-driven gear 50B is mounted on a portion of the length of the odd-numbered gear intermediate shaft <NUM> which is located closest to the first dog-clutch <NUM>. The first speed input gear 45A and the third speed input gear 47A are arranged on the opposite side of the odd-numbered motor-driven gear 50B to the first dog-clutch <NUM>.

The odd-numbered motor-driven gear 50B, the third speed input gear 47A, and the first speed input gear 45A are arranged away from the first dog-clutch <NUM> in the axial direction of the odd-numbered gear intermediate shaft <NUM> and designed to have diameters which are different to decrease stepwise in this order.

The even-numbered motor-driven gear 51B is arranged on a portion of the length of the even-numbered gear intermediate shaft <NUM> which is located closest to the first dog-clutch <NUM>. The second speed input gear 46A and the fourth speed input gear 48A are arranged on the opposite side of the even-numbered motor-driven gear 51B to the first dog-clutch <NUM>.

The even-numbered motor-driven gear 51B, the fourth speed input gear 48A, and the second speed input gear 46A are arranged away from the first dog-clutch <NUM> in this order and designed to have diameters which are different to decrease stepwise in this order.

The output shaft <NUM> has the ring-shaped second dog-clutch <NUM> and the ring-shaped third dog-clutch <NUM> mounted thereon.

The second dog-clutch <NUM> is arranged between the first speed output gear 45B and the third speed output gear 47B in the axial direction of the output shaft <NUM>. The second dog-clutch <NUM> is movable in the axial direction of the output shaft <NUM> and also rotatable along with the output shaft <NUM>.

The second dog-clutch <NUM> includes a plurality of dog teeth 53A arranged on a left end thereof and a plurality of dog teeth 53B arranged on a right end thereof.

The first speed output gear 45B has a plurality of dog teeth <NUM> mounted on a right end thereof. The third speed output gear 47B has a plurality of dog teeth <NUM> mounted on a left end thereof.

The second dog-clutch <NUM> is moved by the actuator <NUM> in the axial direction of the output shaft <NUM>.

When the second dog-clutch <NUM> is moved by the actuator <NUM> from a neutral position thereof to the first speed output gear 45B, so that the dog teeth 53A mesh with the dog teeth <NUM> of the first speed output gear 45B, the second dog-clutch <NUM> achieves the connection of the first speed output gear 45B with the output shaft <NUM>.

The above connection between the first speed output gear 45B and the output shaft <NUM> causes the first speed output gear 45B to rotate together with the output shaft <NUM>, so that the drive power is transmittable between the odd-numbered gear intermediate shaft <NUM> and the output shaft <NUM> through the first speed gear set <NUM>.

When the second dog-clutch <NUM> is moved by the actuator <NUM> from the neutral position toward the third speed output gear 47B, and the dog teeth 53B mesh with the dog teeth <NUM> of the third speed output gear 47B, it causes the third speed output gear 47B to connect with the output shaft <NUM> through the second dog-clutch <NUM>.

The above connection between the third speed output gear 47B and the output shaft <NUM> causes the third speed output gear 47B to rotate together with the output shaft <NUM>, so that the drive power is transmittable between the odd-numbered gear intermediate shaft <NUM> and the output shaft <NUM> through the third speed gear set <NUM>.

The third dog-clutch <NUM> is arranged between the second speed output gear 46B and the fourth speed output gear 48B in the axial direction of the output shaft <NUM>. The third dog-clutch <NUM> is movable in the axial direction of the output shaft <NUM> and also rotatable along with the output shaft <NUM>.

The third dog-clutch <NUM> has a plurality of dog teeth 54A mounted on a right end thereof and a plurality of dog teeth 54B mounted on a left end thereof.

The second speed output gear 46B has a plurality of dog teeth <NUM> formed on a left end thereof. The fourth speed output gear 48B has a plurality of dog teeth <NUM> formed on a right end thereof.

The third dog-clutch <NUM> is moved by the actuator <NUM> in the axial direction of the output shaft <NUM>.

When the third dog-clutch <NUM> is moved by the actuator <NUM> from a neutral position thereof toward the second speed output gear 46B, and the dog teeth 54A mesh with the dog teeth <NUM> of the second speed output gear 46B, it causes the second speed output gear 46B to connect with the output shaft <NUM> through the third dog-clutch <NUM>.

The above connection between the second speed output gear 46B and the output shaft <NUM> causes the second speed output gear 46B to rotate together with the output shaft <NUM>, so that the drive power is transmittable between the even-numbered gear intermediate shaft <NUM> and the output shaft <NUM> through the second speed gear set <NUM>.

When the third dog-clutch <NUM> is moved by the actuator <NUM> from a neutral position thereof toward the fourth speed output gear 48B, and the dog teeth 54B mesh with the dog teeth <NUM> of the fourth speed output gear 48B, it causes the fourth speed output gear 48B to connect with the output shaft <NUM> through the third dog-clutch <NUM>.

The above connection between the fourth speed output gear 48B and the output shaft <NUM> causes the fourth speed output gear 48B to rotate together with the output shaft <NUM>, so that the drive power is transmittable between the even-numbered gear intermediate shaft <NUM> and the output shaft <NUM> through the fourth speed gear set <NUM>.

As apparent from the above discussion, the transmission <NUM> in this embodiment works to select the first or third gear ratio between the odd-numbered gear intermediate shaft <NUM> and the output shaft <NUM>, so that the transmission <NUM> is placed at the first or third speed position. Alternatively, the transmission <NUM> works to select the second or fourth gear ratio between the even-numbered gear intermediate shaft <NUM> and the output shaft <NUM>, so that the transmission <NUM> is placed at the second or fourth speed position.

A power transmission path through which the drive power produced by the engine <NUM> is transmitted when the transmission <NUM> is in the first speed position where the first gear ratio is established or the third speed position where the third gear ratio is established will be a path extending from the crankshaft <NUM> of the engine <NUM> to the output shaft <NUM> through the odd-numbered gear intermediate shaft <NUM> and the first speed gear set <NUM> or the third speed gear set <NUM>.

A power transmission path through which the drive power produced by the engine <NUM> is transmitted when the transmission <NUM> is in the second speed position where the second gear ratio is established or the fourth speed position where the fourth gear ratio is established will be a path extending from the crankshaft <NUM> of the engine <NUM> to the output shaft <NUM> through the input shaft <NUM>, the even-numbered gear intermediate shaft <NUM>, and the second speed gear set <NUM> or the fourth speed gear set <NUM>.

A power transmission path through which the drive power produced by the odd-numbered gear motor generator <NUM> is transmitted when the transmission <NUM> is in the first or third speed position will be a path extending from the odd-numbered gear motor generator <NUM> to the output shaft <NUM> through the odd-numbered motor-drive gear 50A, the odd-numbered motor-driven gear 50B, the odd-numbered gear intermediate shaft <NUM>, and the first speed gear set <NUM> or the third speed gear set <NUM>.

A power transmission path through which the drive power produced by the even-numbered gear motor generator <NUM> is transmitted when the transmission <NUM> is in the second or fourth speed position will be a path extending the even-numbered gear motor generator <NUM> to the output shaft <NUM> through the even-numbered motor-drive gear 51A, the even-numbered motor-driven gear 51B, the even-numbered gear intermediate shaft <NUM>, and the second speed gear set <NUM> or the fourth speed gear set <NUM>.

In this embodiment, the first dog-clutch <NUM> works as a first switching member. The second dog-clutch <NUM> works as a second switching member. The third dog-clutch <NUM> works as a third switching member.

As apparent from the above discussion, the driving of the vehicle <NUM> is achieved using the gear set <NUM>, <NUM>, <NUM> or <NUM> by selecting the operation state of the second dog-clutch <NUM> or the third dog-clutch <NUM> and controlling the drive power produced by the odd-numbered gear motor generator <NUM> or the even-numbered gear motor generator <NUM>. For the sake of convenience, unless otherwise specified, the gear ratios or gears, as referred to herein, represents gear ratios or gears established in the power transmission paths through which the drive power produced by the engine <NUM> is transmitted. The gear change or gear shift means switching of the power transmission paths through which the drive power produced by the engine <NUM> is transmitted.

The output shaft <NUM> has the final drive gear <NUM> mounted on the left end thereof. The differential <NUM> includes the final driven gear 22A meshing with the final drive gear <NUM> and the differential mechanism 22B mounted on the final driven gear 22A.

The differential mechanism 22B is connected to the drive shafts <NUM> and 31R. The differential <NUM> works to distribute the drive power, as produced by the engine <NUM>, to the drive shafts <NUM> and 31R using the differential mechanism 22B, which are, in turn, delivered to the driven wheels <NUM> and 4R.

Each of the HCU <NUM>, the ECU <NUM>, the TCT <NUM>, and the BMS <NUM> is implemented by a computer unit equipped with a CPU (Central Processing Unit), a RAM (Random Access Memory, a ROM (Read Only Memory), a flash memory storing back-up data, an input port, and an output port.

The ROMs of the computers store a variety of constant numbers, a variety of maps, and logical programs for use in operating the computers as the HCU <NUM>, the ECU <NUM>, the TCU <NUM>, and the BMS <NUM>, respectively.

Specifically, each of the CPUs, in the RAM serving as a workspace, the program stored in the ROM to make each of the computer units function as a corresponding one of the HCU <NUM>, the ECU <NUM>, the TCU <NUM>, and the BMS <NUM>.

The ECU <NUM> works to control the quantity of air sucked into the engine <NUM>, the quantity of fuel injected into the engine <NUM>, the injection timing of the engine <NUM>, and the ignition timing of the engine <NUM> to bring the degree of torque generated by the engine <NUM> into agreement with a target value outputted from the HCU <NUM>.

The TCU <NUM> is responsive to a command from the HCU <NUM> to control the operation of the actuator <NUM> to move each of the first dog-clutch <NUM> and the second dog-clutch <NUM> or the third dog-clutch <NUM> between the neutral position thereof and a selected one of the odd-numbered gear positions where the odd gears (i.e., the odd gear ratios) are established or a selected one of the even-numbered gear positions where the even gears (i.e., the even gear ratios) are established.

The BMS <NUM> works to monitor the current state of the battery <NUM> and output information about the state of charge (SOC) of the battery <NUM> to the HCU <NUM>.

Each of the odd-numbered gear inverter <NUM> and the even-numbered gear inverter <NUM> is responsive to a command from the HCU <NUM> to change direct power as supplied from the battery <NUM>, to three-phase alternating power and delivers it to the even-numbered gear motor generator <NUM> or the odd-numbered gear motor generator <NUM> to bring the degree of torque outputted therefrom into agreement with a target value determined by the HCU <NUM>. Each of the odd-numbered gear inverter <NUM> and the even-numbered gear inverter <NUM> also works to convert three-phase alternating power, as produced by the odd-numbered gear motor generator <NUM> or the even-numbered gear motor generator <NUM>, into direct power to charge the battery <NUM>.

The odd-numbered gear inverter <NUM> and the even-numbered gear inverter <NUM> output information about speeds of rotation of the odd-numbered gear motor generator <NUM> and the even-numbered gear motor generator <NUM> to the HCU <NUM>. The battery <NUM> may be made of a secondary battery, such as a lithium-ion battery.

Each of the odd-numbered gear motor generator <NUM> and the even-numbered gear motor generator <NUM> selectively operates in a motor mode or a generator mode. The motor mode is a power generation mode in which each of the odd-numbered gear motor generator <NUM> and the even-numbered gear motor generator <NUM> is actuated by electrical power supplied from the battery <NUM> through a corresponding one of the odd-numbered gear inverter <NUM> and the even-numbered gear inverter <NUM> to produce drive power to move the vehicle <NUM>. The generator mode is a regenerative power mode in which each of the odd-numbered gear motor generator <NUM> and the even-numbered gear motor generator <NUM> is actuated by torque (i.e., counter drive power) inputted thereinto from the driven wheels <NUM> and 4R through the differential <NUM> to generate electrical power.

The odd-numbered gear motor generator <NUM> in this embodiment constitutes a first rotating electrical machine. The even-numbered gear motor generator <NUM> in this embodiment constitutes a second electrical machine.

Referring back to <FIG>, the HCU <NUM> is connected to the shift position sensor <NUM>, the accelerator position sensor <NUM>, and the vehicle speed sensor <NUM>. The shift position sensor <NUM> detects one of positions (also called shift positions) of the shift lever <NUM> selected by a driver of the vehicle <NUM>.

The shift positions include, for example, a P-position (i.e., parking position), an N-position (i.e., neutral position), a R-position (i.e., reverse position to achieve backward motion), a D-position (i.e., drive position to achieve forward motion), and a B-position (i.e., engine braking position). The B-position is a position of the shift lever <NUM> where the degree of engine braking higher than that in the D-position is produced.

The shift position sensor <NUM> outputs a signal indicative of one of the shift positions of the shift lever <NUM> selected by the driver to the HCU <NUM>.

The accelerator position sensor <NUM> detects a position of the accelerator pedal <NUM> operated by the driver of the vehicle <NUM> (i.e., the degree of driver's effort on the accelerator pedal <NUM>) and outputs a signal indicative thereof to the HCU <NUM>. The vehicle speed sensor <NUM> measures the speed of the vehicle <NUM> and outputs a signal indicative thereof to the HCU <NUM>.

The HCU <NUM> analyzes the position of the shift lever <NUM> detected by the shift position sensor <NUM>, the position of the accelerator pedal <NUM> measured by the accelerator position sensor <NUM>, and the vehicle speed measured by the vehicle speed sensor <NUM> to calculate the degree of drive power requested by the driver of the vehicle <NUM> (i.e., the degree of driver-requested torque) to select one of an EV mode or a HEV mode and switch a drive mode of the vehicle <NUM> to the selected one of the EV mode and the HEV mode.

The EV mode is a mode in which the vehicle <NUM> is driven by the odd-numbered gear motor generator <NUM> or the even-numbered gear motor generator <NUM> without use of drive power generated by the engine <NUM>. The HEV mode is a mode in which the engine <NUM> is placed in an operation mode where the drive power generated by the engine <NUM> is transmittable to the drive wheels <NUM> and 4R.

In each of the EV mode and the HEV mode, the HCU <NUM> outputs commands to the ECU <NUM>, the TCU <NUM>, the odd-numbered gear inverter <NUM>, and the even-numbered gear inverter <NUM> in order to produce the degree of driver-requested torque in a given range of the SOC of the battery <NUM>.

The odd-numbered gear inverter <NUM> and the even-numbered gear inverter <NUM> are responsive to the commands from the HCU <NUM> to control drive powers or torques outputted by the odd-numbered gear motor generator <NUM> and the even-numbered gear motor generator <NUM>, respectively. The ECU <NUM> is responsive to the command from the HCU <NUM> to control the degree of torque outputted by the engine <NUM>.

The TCU <NUM> is responsive to the command from the HCU <NUM> to control the operation of the actuator <NUM> to switch the states of the first dog-clutch <NUM>, the second dog-clutch <NUM>, and the third dog-clutch <NUM> to perform the gear change.

The EV mode is a driving mode in which the engine <NUM> is stopped, and the odd-numbered gear motor generator <NUM> or the even-numbered gear motor generator <NUM> is actuated to produce the degree of driver's requested torque to move the vehicle <NUM>.

In the EV mode, the engine <NUM> is not operated, so that the speed of the engine <NUM> is kept zero.

The HEV mode is a driving mode in which the engine <NUM> is basically operated to meet the degree of driver's requested torque to move the vehicle <NUM>. Specifically, when a condition where the degree of torque generated only by the engine <NUM> is sufficient to meet the degree of driver's requested torque is encountered, only the engine <NUM> is operated to move the vehicle <NUM>. Alternatively, when a condition where the degree of torque generated only by the engine <NUM> is insufficient to meet the degree of driver's requested torque is encountered, one of the odd-numbered gear motor generator <NUM> and the even-numbered gear motor generator <NUM> is additionally operated to meet the degree of driver's requested torque to move the vehicle <NUM>.

In other words, the HEV mode includes a driving mode in which only the engine torque is used to move the vehicle <NUM> and a motor-assist mode in which both the engine torque and the motor torque are used to move the vehicle <NUM>.

When it is required to change from one of the odd gear ratios to one of the even gear ratios or vice versa in the transmission <NUM>, the HCU <NUM> analyses the information outputted from the shift position sensor <NUM>, the accelerator position sensor <NUM>, and the vehicle speed sensor <NUM> to control the operation of the ECU <NUM> to decrease the degree of drive power produced by the engine <NUM> down to a selected value.

Specifically, the HCU <NUM> controls the operation of the ECU <NUM> to close a throttle valve to regulate the quantity of air intake into the engine <NUM> to decrease the drive power down to the selected value.

When the drive power produced by the engine <NUM> is decreased down to the selected value, the HCU <NUM> controls the operation of the odd-numbered gear inverter <NUM> or the even-numbered gear inverter <NUM> to increase the torque which is outputted by the odd-numbered gear motor generator <NUM> and exerted on the odd-numbered gear intermediate shaft <NUM> equipped with the first speed gear set <NUM> and the third speed gear set <NUM> one of which achieves a current one of the gear ratios or which is outputted by the even-numbered gear motor generator <NUM> and exerted on the even-numbered gear intermediate shaft <NUM> equipped with the second speed gear set <NUM> and the fourth speed gear set <NUM> one of which establishes the current gear ratio in order to compensate for a decrease in driver power produced by the engine <NUM>.

Subsequently, the HCU <NUM> controls the operations of the ECU <NUM> and the odd-numbered gear inverter <NUM> or the even-numbered gear inverter <NUM> to synchronize the speed of the odd-numbered gear intermediate shaft <NUM> or the even-numbered gear intermediate shaft <NUM> whichever is required to establish the next gear ratio to which the current gear ratio is to be changed with the speed of the input shaft <NUM>.

Specifically, when the driver power produced by the engine <NUM> has dropped down to the selected value, the HCU <NUM> controls the operation of the TCU <NUM> to change one of the odd-numbered gear position and the even-numbered gear position of the first dog-clutch <NUM> which is achieving the current gear ratio to the neutral position thereof.

Subsequently, the HCU <NUM> controls the operations of the ECU <NUM> and the odd-numbered gear inverter <NUM> or the even-numbered gear inverter <NUM> to achieve synchronization of the speed of the odd-numbered gear intermediate shaft <NUM> or the even-numbered gear intermediate shaft <NUM> whichever is required to establish the next gear ratio with that of the input shaft <NUM>.

Upon the synchronization of the speed of the odd-numbered gear intermediate shaft <NUM> with that of the input shaft <NUM> or the speed of the even-numbered gear intermediate shaft <NUM> with that of the input shaft <NUM>, the HCU <NUM> controls the operation of the TCU <NUM> to move the first dog-clutch <NUM> from the neutral position thereof to the odd-numbered gear position or the even-numbered gear position which is required to establish the next gear ratio.

When it is required to change the odd gear ratio to the even gear ratio in the transmission <NUM>, the HCU <NUM> shifts the first dog-clutch <NUM> from the neutral position to the even-numbered gear position thereof and then controls the operation of the ECU <NUM>, the odd-numbered gear inverter <NUM>, and the even-numbered gear inverter <NUM> to synchronize the speed of the second speed output gear 46B or the fourth speed output gear 48B with that of the output shaft <NUM>. When such speed synchronization is completed, the third dog-clutch <NUM> works to connect the second speed output gear 46B or the fourth speed output gear 48B with the output shaft <NUM>.

Alternatively, when it is required to change the even gear ratio to the odd gear ratio in the transmission <NUM>, the HCU <NUM> shifts the first dog-clutch <NUM> from the neutral position to the odd-numbered gear position thereof and then controls the operation of the ECU <NUM>, the odd-numbered gear inverter <NUM>, and the even-numbered gear inverter <NUM> to synchronize the speed of the first speed output gear 45B or the third speed output gear 47B with that of the output shaft <NUM>. When such speed synchronization is completed, the second dog-clutch <NUM> works to connect the first speed output gear 45B or the third speed output gear 47B with the output shaft <NUM>.

When it is required to change the odd gear ratio to the even gear ratio in the transmission <NUM>, the HCU <NUM> also works to shift the third dog-clutch <NUM> to the neutral position thereof simultaneously with when the first dog-clutch <NUM> is shifted to the neutral position thereof. Alternatively, when it is required to change the even gear ratio to the odd gear ratio in the transmission <NUM>, the HCU <NUM> also works to shift the second dog-clutch <NUM> to the neutral position thereof simultaneously with when the first dog-clutch <NUM> is shifted to the neutral position thereof.

The HCU <NUM>, the ECU <NUM>, the TCU <NUM>, the odd-numbered gear inverter <NUM>, and the even-numbered gear inverter <NUM> constitute the controller <NUM>.

The switching operations of the first dog-clutch <NUM>, the second dog-clutch <NUM>, and the third dog-clutch <NUM> in each of the EV mode and the HEV mode will be described below with reference to a position shift schedule demonstrated in <FIG>.

The EV neutral mode is included in the EV mode which is entered when the shift lever <NUM> is shifted to in the N-position or the P-position. Each of the first dog-clutch <NUM>, the second dog-clutch <NUM>, and the third dog-clutch <NUM> is placed in the neutral position thereof.

Consequently, the engine <NUM>, the odd-numbered gear motor generator <NUM>, and the even-numbered gear motor generator <NUM> are out of connection with the driven wheels <NUM> and 4R, so that neither of the engine torque and the motor torque is transmitted from the engine <NUM>, the odd-numbered gear motor generator <NUM>, and the even-numbered gear motor generator <NUM> to the driven wheels <NUM> and 4R.

In the EV neutral mode, the second dog-clutch <NUM> and the third dog-clutch <NUM> are in the neutral position, but however, they may alternatively be out of the neutral position as long as the odd-numbered gear motor generator <NUM> and the even-numbered gear motor generator <NUM> are placed in off-positions thereof to produce no motor torque.

The EV1-EV2 mode is included in the EV mode entered when the shift lever <NUM> is in the D-position or the P-position.

Specifically, when the EV1-EV2 mode is entered, the first dog-clutch <NUM> is shifted to the neutral position, while the second dog-clutch <NUM> is shifted to the position which achieves the first gear (i.e., the first gear ratio) and will also be referred to below as a first gear position, and the third dog-clutch <NUM> is shifted to the position which achieves the second gear (i.e., the second gear ratio) and will also be referred to below as a second gear position.

When the vehicle <NUM> travels forward in the EV1-EV2 mode, the torque, as produced by the odd-numbered gear motor generator <NUM>, is delivered from the odd-numbered gear intermediate shaft <NUM> to the output shaft <NUM> through the first speed gear set <NUM>, while the torque, as produced by the even-numbered gear motor generator <NUM>, is delivered from the even-numbered gear intermediate shaft <NUM> to the output shaft <NUM> through the second speed gear set <NUM>, thereby transmitting the torque produced by the motor generators <NUM> and <NUM> to the driven wheels <NUM> and 4R.

Alternatively, when the vehicle <NUM> is required to travel backward, the odd-numbered gear motor generator <NUM> and the even-numbered gear motor generator <NUM> are rotated in a reverse direction opposite that in which the vehicle <NUM> travels forward, so that torque produced by the odd-numbered gear motor generator <NUM> and the even-numbered gear motor generator <NUM> is transmitted to the driven wheels <NUM> and 4R through the same power transmission path as when the vehicle <NUM> travels forward.

When the vehicle <NUM> is being decelerated, the torque is transmitted from the driven wheels <NUM> and 4R to the output shaft <NUM> through the differential <NUM>.

The torque transmitted to the output shaft <NUM> is delivered from the first speed gear set <NUM> to the odd-numbered gear motor generator <NUM> through the odd-numbered gear intermediate shaft <NUM> and also from the second speed gear set <NUM> to the even-numbered gear motor generator <NUM> through the even-numbered gear intermediate shaft <NUM>, thereby placing the motor generators <NUM> and <NUM> in the regenerative mode.

The EV2 mode is included in the EV mode entered when the shift lever <NUM> is in the D-position.

Specifically, when the EV2 mode is entered, the first dog-clutch <NUM> and the second dog-clutch <NUM> are shifted to the neutral position, while the third dog-clutch <NUM> is shifted to the position which achieves the second gear ratio.

When the vehicle <NUM> travels forward in the EV2 mode, the torque produced by the even-numbered gear motor generator <NUM> is delivered from the even-numbered gear intermediate shaft <NUM> to the output shaft <NUM> through the second speed gear set <NUM>. In brief, the torque is transmitted the even-numbered gear motor generator <NUM> to the driven wheels <NUM> and 4R.

The EV2 mode is entered for a temporary period of time when the EV1-EV2 mode is changed to the EV2-EV3 mode. Specifically, during a shift from the first gear to the third gear in the transmission <NUM>, the driven wheels <NUM> and 4R are rotated or driven using the torque produced by the even-numbered gear motor generator <NUM>.

The EV2-EV3 mode is included in the EV mode entered when the shift lever <NUM> is in the D-position.

Specifically, when the EV2-EV3 mode is entered, the first dog-clutch <NUM> is shifted to the neutral position, while the second dog-clutch <NUM> is shifted to the position which achieves the third gear ratio, and the third dog-clutch <NUM> is shifted to the position which achieves the second gear ratio.

When the vehicle <NUM> travels forward in the EV2-EV3 mode, the torque produced by the odd-numbered gear motor generator <NUM> is delivered from the odd-numbered gear intermediate shaft <NUM> to the output shaft <NUM> through the third speed gear set <NUM>. Simultaneously, the torque produced by the even-numbered gear motor generator <NUM> is delivered from the even-numbered gear intermediate shaft <NUM> to the output shaft <NUM> through the second speed gear set <NUM>. In brief, the torque produced by the motor generators <NUM> and <NUM> is transmitted to the driven wheels <NUM> and 4R.

When the vehicle <NUM> is being decelerated, the torque is delivered from the driven wheels <NUM> and 4R to the output shaft <NUM> through the differential <NUM>.

The torque transmitted to the output shaft <NUM> is delivered from the third speed gear set <NUM> to the odd-numbered gear motor generator <NUM> through the odd-numbered gear intermediate shaft <NUM> and also from the second speed gear set <NUM> to the even-numbered gear motor generator <NUM> through the even-numbered gear intermediate shaft <NUM>, thereby placing the motor generators <NUM> and <NUM> in the regenerative mode.

The EV2-EV3 mode is not entered in the R-position since the vehicle <NUM> does not need to be accelerated when traveling in the backward direction.

The EV3 mode is included in the EV mode entered when the shift lever <NUM> is in the D-position.

Specifically, when the EV3 mode is entered, the first dog-clutch <NUM> and the third dog-clutch <NUM> are shifted to the neutral positions thereof, while the second dog-clutch <NUM> is shifted to the position which achieves the third gear ratio.

When the vehicle <NUM> travels forward in the EV3 mode, the torque produced by the odd-numbered gear motor generator <NUM> is delivered to the output shaft <NUM> through the third speed gear set <NUM>. In brief, the torque is transmitted from the odd-numbered gear motor generator <NUM> to the driven wheels <NUM> and 4R.

The EV3 mode is entered for a temporary period of time when the EV2-EV3 mode is changed to the EV3-EV4 mode. Specifically, during a shift from the second gear to the fourth gear in the transmission <NUM>, the driven wheels <NUM> and 4R are rotated using the torque produced by the odd-numbered gear motor generator <NUM>.

The EV3-EV4 mode is included in the EV mode entered when the shift lever <NUM> is in the D-position.

Specifically, when the EV3-EV4 mode is entered, the first dog-clutch <NUM> is shifted to the neutral position, while the second dog-clutch <NUM> is shifted to the position which achieves the third gear ratio, and the third dog-clutch <NUM> is shifted to the position which achieves the fourth gear ratio.

When the vehicle <NUM> travels forward in the EV3-EV4 mode, the torque produced by the odd-numbered gear motor generator <NUM> is delivered from the odd-numbered gear intermediate shaft <NUM> to the output shaft <NUM> through the third speed gear set <NUM>, while the torque produced by the even-numbered gear motor generator <NUM> is delivered from the even-numbered gear intermediate shaft <NUM> to the output shaft <NUM> through the fourth speed gear set <NUM>. In brief, the torque produced by the motor generators <NUM> and <NUM> is used to rotate the driven wheels <NUM> and 4R.

When the vehicle <NUM> is decelerating, the torque is transmitted from the driven wheels <NUM> and 4R to the output shaft <NUM> through the differential <NUM>.

The torque transmitted to the output shaft <NUM> is then delivered from the third speed gear set <NUM> to the odd-numbered gear motor generator <NUM> through the odd-numbered gear intermediate shaft <NUM> and also from the fourth speed gear set <NUM> to the even-numbered gear motor generator <NUM> through the even-numbered gear intermediate shaft <NUM>, thereby placing the motor generators <NUM> and <NUM> in the regenerative mode.

The EV3-EV4 mode is not entered in the R-position since the vehicle <NUM> does not need to be accelerated when traveling in the backward direction.

The HEV neutral mode is included in the HEV mode entered when the shift lever <NUM> in in the N-position or the P-position.

When the HEV neutral mode is entered, each of the first dog-clutch <NUM>, the second dog-clutch <NUM>, and the third dog-clutch <NUM> is placed in the neutral position.

The engine <NUM>, the odd-numbered gear motor generator <NUM>, and the even-numbered gear motor generator <NUM> are, therefore, out of connection with the driven wheels <NUM> and 4R, so that no torque is delivered from the engine <NUM>, the odd-numbered gear motor generator <NUM>, and the even-numbered gear motor generator <NUM> to the driven wheels <NUM> and 4R.

In the HEV neutral mode, the second dog-clutch <NUM> and the third dog-clutch <NUM> are placed in the neutral position, but however, they may alternatively be out of the neutral position as long as the odd-numbered gear motor generator <NUM> and the even-numbered gear motor generator <NUM> are placed in off-positions thereof to produce no motor torque.

The HEV neutral power generation mode is included in the HEV mode entered when the shift lever <NUM> is in the N-position or the P-position.

When the HEV neutral power generation mode is entered, the first dog-clutch <NUM> is shifted to the even-numbered gear position, while the second dog-clutch <NUM> and the third dog-clutch <NUM> are placed in the neutral positions thereof.

In the HEV neutral power generation mode, the input shaft <NUM> is connected to the even-numbered gear intermediate shaft <NUM> through the first dog-clutch <NUM>, so that the torque produced by the engine <NUM> is delivered from the input shaft <NUM> to the even-numbered gear motor generator <NUM> through the even-numbered gear intermediate shaft <NUM>, thereby placing the even-numbered gear motor generator <NUM> in the power generation mode.

In the HEV neutral power generation mode, the second dog-clutch <NUM> and the third dog-clutch <NUM> are placed in the neutral position, but however, they may alternatively be out of the neutral position as long as the odd-numbered gear motor generator <NUM> and the even-numbered gear motor generator <NUM> are placed in off-positions thereof to produce no motor torque.

The HEV1-EV1-EV2 mode is included in the HEV mode entered when the shift lever <NUM> is in the D-position.

When the HEV1-EV1-EV2 mode is entered, the first dog-clutch <NUM> is shifted to the odd-numbered gear position, the second dog-clutch <NUM> is shifted to the position which achieves the first gear ratio, and the third dog-clutch <NUM> is shifted to the position which achieves the second gear ratio.

When the vehicle <NUM> travels forward in the HEV1-EV1-EV2 mode, the input shaft <NUM> is connected to the odd-numbered gear intermediate shaft <NUM>.

The above connection of the input shaft <NUM> to the odd-numbered gear intermediate shaft <NUM> causes torque produced by the engine <NUM> and the odd-numbered gear motor generator <NUM> to be delivered from the odd-numbered gear intermediate shaft <NUM> to the output shaft <NUM> through the first speed gear set <NUM>. The torque produced by the even-numbered gear motor generator <NUM> becomes transmittable from the even-numbered gear intermediate shaft <NUM> to the output shaft <NUM> through the second speed gear set <NUM>.

Consequently, at least the engine <NUM> and the odd-numbered gear motor generator <NUM> are used to rotate the driven wheels <NUM> and 4R. When it is required to assist the engine <NUM>, both the odd-numbered gear motor generator <NUM> and the even-numbered gear motor generator <NUM> are actuated.

When the vehicle <NUM> is traveling, and it is required to operate the odd-numbered gear motor generator <NUM> to generate electricity in the power generation mode using the torque produced by the engine <NUM>, the torque outputted by the engine <NUM> is delivered from the odd-numbered gear intermediate shaft <NUM> to the odd-numbered gear motor generator <NUM>. When the vehicle <NUM> is traveling, and it is required to operate the even-numbered gear motor generator <NUM> to generate electricity in the power generation mode using the torque produced by the engine <NUM>, the torque outputted by the engine <NUM> is delivered from the odd-numbered gear intermediate shaft <NUM> to the output shaft <NUM> through the first speed gear set <NUM>, to the second speed gear set <NUM>, to the even-numbered gear intermediate shaft <NUM>, and then to the even-numbered gear motor generator <NUM>.

When it is required to operate the odd-numbered gear motor generator <NUM> and the even-numbered gear motor generator <NUM> in the regenerative mode, the torque is delivered from the output shaft <NUM> to the odd-numbered gear motor generator <NUM> through the first speed gear set <NUM> and the odd-numbered gear intermediate shaft <NUM> and also from the output shaft <NUM> to the even-numbered gear motor generator <NUM> through the second speed gear set <NUM> and the even-numbered gear intermediate shaft <NUM>.

The HEV2-EVI-EV2 mode is included in the HEV mode entered when the shift lever <NUM> is in the D-position.

When the HEV2-EV1-EV2 mode is entered, the first dog-clutch <NUM> is shifted to the even-numbered gear position, while the second dog-clutch <NUM> is shifted to the position which achieves the first gear ratio, and the third dog-clutch <NUM> is shifted to the position which achieves the second gear ratio.

When the vehicle <NUM> travels forward in the HEV2-EV1-EV2 mode, the input shaft <NUM> is coupled with the even-numbered gear intermediate shaft <NUM>.

The above coupling of the input shaft <NUM> with the even-numbered gear intermediate shaft <NUM> causes the torque produced by the engine <NUM> and the even-numbered gear motor generator <NUM> to be delivered from the even-numbered gear intermediate shaft <NUM> to the output shaft <NUM> through the second speed gear set <NUM>. The torque produced by the odd-numbered gear motor generator <NUM> becomes transmittable from the odd-numbered gear intermediate shaft <NUM> to the output shaft <NUM> through the first speed gear set <NUM>.

The above torque delivery causes the driven wheels <NUM> and 4R to be operated using at least the engine <NUM> and the even-numbered gear motor generator <NUM>. When it is required to assist the engine <NUM>, both the odd-numbered gear motor generator <NUM> and the even-numbered gear motor generator <NUM> are actuated.

When the vehicle <NUM> is traveling, and it is required to operate the even-numbered gear motor generator <NUM> to generate electricity in the power generation mode using the torque produced by the engine <NUM>, the torque outputted by the engine <NUM> is delivered from the even-numbered gear intermediate shaft <NUM> to the even-numbered gear motor generator <NUM>. When the vehicle <NUM> is traveling, and it is required to operate the odd-numbered gear motor generator <NUM> to generate electricity in the power generation mode using the torque produced by the engine <NUM>, the torque outputted by the engine <NUM> is delivered from the even-numbered gear intermediate shaft <NUM> to the output shaft <NUM> through the second speed gear set <NUM>, to the first speed gear set <NUM>, to the odd-numbered gear intermediate shaft <NUM>, and then to the odd-numbered gear motor generator <NUM>.

When it is required to operate the odd-numbered gear motor generator <NUM> and the even-numbered gear motor generator <NUM> in the regenerative mode, the same operation as in the HEV1-EV1-EV2 mode is performed.

The HEV2-EV3-EV2 mode is included in the HEV mode entered when the shift lever <NUM> is in the D-position.

When the HEV2-EV3-EV2 mode is entered, the first dog-clutch <NUM> is shifted to the even-numbered gear position, while the second dog-clutch <NUM> is shifted to the position which achieves the third gear ratio, and the third dog-clutch <NUM> is shifted to the position which achieves the second gear ratio.

When the vehicle <NUM> travels forward in the HEV2-EV3-EV2 mode, the input shaft <NUM> is connected to the even-numbered gear intermediate shaft <NUM>.

The connection of the input shaft <NUM> to the even-numbered gear intermediate shaft <NUM> causes the torque produced by the engine <NUM> and the even-numbered gear motor generator <NUM> to be delivered from the even-numbered gear intermediate shaft <NUM> to the output shaft <NUM> through the second speed gear set <NUM>. The torque produced by the odd-numbered gear motor generator <NUM> becomes transmittable from the odd-numbered gear intermediate shaft <NUM> to the output shaft <NUM> through the third speed gear set <NUM>.

When it is required to assist the engine <NUM>, both the odd-numbered gear motor generator <NUM> and the even-numbered gear motor generator <NUM> are actuated.

In the power generation mode, only the even-numbered gear motor generator <NUM> or both the odd-numbered gear motor generator <NUM> and the even-numbered gear motor generator <NUM> are actuated to generate the electricity using a portion of torque produced by the engine <NUM>.

The HEV3-EV3-EV2 mode is included in the HEV mode entered when the shift lever <NUM> is in the D-position.

When the HEV3-EV3-EV2 mode is entered, the first dog-clutch <NUM> is shifted to the odd-numbered gear position, the second dog-clutch <NUM> is shifted to the position which achieves the third gear ratio, and the third dog-clutch <NUM> is shifted to the position which achieves the second gear ratio.

When the vehicle <NUM> travels forward in the HEV3-EV3-EV2 mode, the input shaft <NUM> is connected to the odd-numbered gear intermediate shaft <NUM>.

The connection of the input shaft <NUM> to the odd-numbered gear intermediate shaft <NUM> causes the torque produced by the engine <NUM> and the odd-numbered gear motor generator <NUM> to be delivered from the odd-numbered gear intermediate shaft <NUM> to the output shaft <NUM> through the third speed gear set <NUM>. The torque produced by the even-numbered gear motor generator <NUM> becomes transmittable from the even-numbered gear intermediate shaft <NUM> to the output shaft <NUM> through the second speed gear set <NUM>.

In the power generation mode, only the odd-numbered gear motor generator <NUM> or both the odd-numbered gear motor generator <NUM> and the even-numbered gear motor generator <NUM> are actuated to generate the electricity using a portion of torque produced by the engine <NUM>.

The HEV3-EV3-EV4 mode is included in the HEV mode entered when the shift lever <NUM> is in the D-position.

When HEV3-EV3-EV4 mode is entered, the first dog-clutch <NUM> is shifted to the odd-numbered gear position, the second dog-clutch <NUM> is shifted to the position which achieves the third gear ratio, and the third dog-clutch <NUM> is shifted to the position which achieves the fourth gear ratio.

When the vehicle <NUM> travels forward in the HEV3-EV3-EV4 mode, the input shaft <NUM> is connected to the odd-numbered gear intermediate shaft <NUM>.

The connection of the input shaft <NUM> to the odd-numbered gear intermediate shaft <NUM> causes the torque produced by the engine <NUM> and the odd-numbered gear motor generator <NUM> to be delivered from the odd-numbered gear intermediate shaft <NUM> to the output shaft <NUM> through the third speed gear set <NUM>. The torque produced by the even-numbered gear motor generator <NUM> becomes transmittable from the even-numbered gear intermediate shaft <NUM> to the output shaft <NUM> through the fourth speed gear set <NUM>.

The HEV4-EV3-EV4 mode is included in the HEV mode entered when the shift lever <NUM> is in the D-position.

When HEV4-EV3-EV4 mode is entered, the first dog-clutch <NUM> is shifted to the even-numbered gear position, the second dog-clutch <NUM> is shifted to the position which achieves the third gear ratio, and the third dog-clutch <NUM> is shifted to the position which achieves the fourth gear ratio.

When the vehicle <NUM> travels forward in the HEV4-EV3-EV4 mode, the input shaft <NUM> is connected to the even-numbered gear intermediate shaft <NUM>.

The connection of the input shaft <NUM> to the even-numbered gear intermediate shaft <NUM> causes the torque produced by the engine <NUM> and the even-numbered gear motor generator <NUM> to be delivered from the even-numbered gear intermediate shaft <NUM> to the output shaft <NUM> through the fourth speed gear set <NUM>. The torque produced by the odd-numbered gear motor generator <NUM> becomes transmittable from the odd-numbered gear intermediate shaft <NUM> to the output shaft <NUM> through the third speed gear set <NUM>.

The EV1 series mode is included in the HEV mode entered when the shift lever <NUM> is in the D-position or the R-position. The EV1 series mode is a mode in which the torque produced by the odd-numbered gear motor generator <NUM> is delivered to the output shaft <NUM> through the first speed gear set <NUM>, thereby moving the vehicle <NUM>. The torque produced by the engine <NUM> is transmitted to the even-numbered gear motor generator <NUM> through the even-numbered gear intermediate shaft <NUM>, thereby placing the even-numbered gear motor generator <NUM> in the power generation mode to generate electricity.

When the EV1 series mode is entered, the first dog-clutch <NUM> is shifted to the even-numbered gear position, the second dog-clutch <NUM> is shifted to the position which achieves the first gear ratio, and the third dog-clutch <NUM> is placed in the neutral position.

When the vehicle <NUM> travels forward in the EV1 series mode, the torque produced by the odd-numbered gear motor generator <NUM> is transmitted from the odd-numbered gear intermediate shaft <NUM> to the output shaft <NUM> through the first speed gear set <NUM>.

When the vehicle <NUM> travels backward, the odd-numbered gear motor generator <NUM> is rotated in the reverse direction opposite the direction in which the vehicle <NUM> travels forward. The torque produced by the odd-numbered gear motor generator <NUM> is delivered to the output shaft <NUM> through the first speed gear set <NUM>.

When the vehicle <NUM> is decelerating, the torque is transmitted from the driven wheels <NUM> and 4R to the differential <NUM>, to the output shaft <NUM>, to the first speed gear set <NUM> and the odd-numbered gear intermediate shaft <NUM>, and then to the odd-numbered gear motor generator <NUM>, thereby placing the odd-numbered gear motor generator <NUM> in the regenerative mode.

When it is required to generate electricity using the even-numbered gear motor generator <NUM>, the torque produced by the engine <NUM> is delivered from the input shaft <NUM> to the even-numbered gear motor generator <NUM> through the even-numbered gear intermediate shaft <NUM>.

The EV1 series mode is performed mainly when the vehicle <NUM> is started at the D-position in the HEV mode or the vehicle <NUM> is moving backward at the R-position in the HEV mode.

The EV1 series mode is also performed in an engine start mode to start the engine <NUM> for a temporary period of time during a shift from the EV1-EV2 mode in the EV-mode to the HEV2-EV1-EV2 mode in the HEV mode.

The EV2 series mode is included in the HEV mode entered when the shift lever <NUM> is in the D-position. The EV2 series mode is a mode in which the vehicle <NUM> is driven using the even-numbered gear motor generator <NUM>, and the torque produced by the engine <NUM> is used to actuate the odd-numbered gear motor generator <NUM> to generate electricity in the power generation mode.

When the EV2 series mode is entered, the first dog-clutch <NUM> is shifted to the odd-numbered gear position, the second dog-clutch <NUM> is placed in the neutral position, and the third dog-clutch <NUM> is shifted to the position which achieves the second gear ratio.

When the vehicle <NUM> travels forward in the EV2 series mode, the torque produced by the even-numbered gear motor generator <NUM> is delivered from the even-numbered gear intermediate shaft <NUM> to the output shaft <NUM> through the second speed gear set <NUM>.

When the vehicle <NUM> is decelerating, the torque is transmitted from the driven wheels <NUM> and 4R to the differential <NUM>, to the output shaft <NUM>, to the second speed gear set <NUM> and the even-numbered gear intermediate shaft <NUM>, and then to the even-numbered gear motor generator <NUM>, thereby placing the even-numbered gear motor generator <NUM> in the regenerative mode.

When it is required to use the odd-numbered gear motor generator <NUM> to generate electricity in the power generation mode, the torque produced by the engine <NUM> is delivered from the input shaft <NUM> to the odd-numbered gear motor generator <NUM> through the odd-numbered gear intermediate shaft <NUM>.

The EV2 series mode is also performed in the engine start mode to start the engine <NUM> for a temporarily period of time during a shift from the EV1-EV2 mode in the EV-mode to the HEV1-EV1-EV2 mode in the HEV mode or to the HEV3-EV3-EV2 mode in the HEV mode.

The EV3 series mode is included in the HEV mode entered when the shift lever <NUM> is in the D-position. The EV3 series mode is a mode in which the vehicle <NUM> is driven or moved using the odd-numbered gear motor generator <NUM>, and the torque produced by the engine <NUM> is used to actuate the even-numbered gear motor generator <NUM> to generate electricity in the power generation mode.

When the EV3 mode is entered, the first dog-clutch <NUM> is shifted to the even-numbered gear position, the second dog-clutch <NUM> is shifted to the position which achieves the third gear ratio, and the third dog-clutch <NUM> is placed in the neutral position.

When the vehicle <NUM> travels forward in the EV3 mode, the torque produced by the odd-numbered gear motor generator <NUM> is delivered from the odd-numbered gear intermediate shaft <NUM> to the output shaft <NUM> through the third speed gear set <NUM>.

When the vehicle <NUM> is decelerating, the torque is delivered from the driven wheels <NUM> and 4R to the output shaft <NUM> through the differential <NUM>, to the third speed gear set <NUM> and the odd-numbered gear intermediate shaft <NUM>, and then to the odd-numbered gear motor generator <NUM>, thereby placing the odd-numbered gear motor generator <NUM> in the regenerative mode.

When it is required to actuate the even-numbered gear motor generator <NUM> to generate electricity in the power generation mode, the torque produced by the engine <NUM> is delivered from the input shaft <NUM> to the even-numbered gear motor generator <NUM> through the even-numbered gear intermediate shaft <NUM>.

The EV3 mode is also performed in the engine start mode to start the engine <NUM> for a temporarily period of time during a shift from the EV1-EV3 mode in the EV-mode to the HEV2-EV3-EV2 mode in the HEV mode or to the HEV4-EV3-EV4 mode in the HEV mode.

The EV4 series mode is included in the HEV mode entered when the shift lever <NUM> is in the D-position. The EV4 series mode is a mode in which the vehicle <NUM> is driven or moved using the even-numbered gear motor generator <NUM>, and the torque produced by the engine <NUM> is used to actuate the odd-numbered gear motor generator <NUM> to generate electricity in the power generation mode.

When the EV4 series mode is entered, the first dog-clutch <NUM> is shifted to the odd-numbered gear position, the second dog-clutch <NUM> is placed in the neutral position, and the third dog-clutch <NUM> is shifted to the position which achieves the fourth gear ratio.

When the vehicle <NUM> travels forward in the EV4 series mode, the torque produced by the even-numbered gear motor generator <NUM> is delivered from the even-numbered gear intermediate shaft <NUM> to the output shaft <NUM> through the fourth speed gear set <NUM>.

When the vehicle <NUM> is decelerating, the torque is delivered from the driven wheels <NUM> and 4R to the output shaft <NUM> through the differential <NUM>, to the fourth speed gear set <NUM> and the even-numbered gear intermediate shaft <NUM>, and then to the even-numbered gear motor generator <NUM>, thereby placing the even-numbered gear motor generator <NUM> in the regenerative mode.

When it is required to generate electricity using the odd-numbered gear motor generator <NUM>, the torque produced by the engine <NUM> is delivered from the input shaft <NUM> to the odd-numbered gear motor generator <NUM> through the odd-numbered gear intermediate shaft <NUM>.

The EV4 mode is also performed in the engine start mode to start the engine <NUM> for a temporarily period of time during a shift from the EV3-EV4 mode in the EV-mode to the HEV3-EV3-EV4 mode in the HEV mode.

The above gear changing operations of the engine <NUM> and the transmission <NUM> are controlled by the controller <NUM> and will also be discussed with reference to timing charts demonstrated in <FIG>. The timing charts in <FIG> illustrate gear changing tasks performed when the first gear is changed to the second gear in the HEV mode.

The timing charts in <FIG> represent, from top to bottom, speeds of the engine <NUM>, the odd-numbered gear motor generator <NUM> (indicated by MG1), the even-numbered gear motor generator <NUM> (indicated by MG2), and the vehicle <NUM>, torque requested by the driver of the vehicle <NUM>, torque produced by the engine <NUM>, and torque produced by the MG1 and MG2, and shiftable positions of the first dog-clutch <NUM>, the second dog-clutch <NUM>, and the third dog-clutch <NUM>. The horizontal axis indicates elapsed time. The timing charts show only changes in the speeds, but not actual values of the speeds.

In <FIG>, the speed of the vehicle <NUM> and the torque requested by the driver of the vehicle <NUM> are indicated by solid lines. The speeds of the engine <NUM> and torque outputted by the engine <NUM> are indicated by broken lines. The speed of and torque produced by the odd-numbered gear motor generator <NUM> are indicated by alternate long and short dash lines. The speed of and torque produced by the even-numbered gear motor generator <NUM> are indicated by alternate long and two short dashes line.

At time t0, the vehicle <NUM> is moving in the first gear in the HEV mode. The first dog-clutch <NUM> is in the odd-numbered gear position. The second dog-clutch <NUM> is in the position which establishes the first gear. The third dog-clutch <NUM> is in the position which establishes the second gear. The HEV1-EV1-EV2 mode is entered as the driving mode of the vehicle <NUM>.

The drive power produced by the engine <NUM> is delivered from the odd-numbered gear intermediate shaft <NUM> to the driven wheels <NUM> and 4R through the first speed gear set <NUM>. The drive power produced by the odd-numbered gear motor generator <NUM> is also delivered to the driven wheels <NUM> and 4R through the first speed gear set <NUM>. The drive power produced by the even-numbered gear motor generator <NUM> is transmittable to the driven wheels <NUM> and 4R through the second speed gear set <NUM>.

At time t1 when the accelerator pedal <NUM> is depressed by the driver of the vehicle <NUM>, the drive power produced by the engine <NUM> is increased, thereby increasing the speeds of the engine <NUM> and the vehicle <NUM>, i.e., accelerating the vehicle <NUM>. After the vehicle <NUM> is accelerated, the gear change is started at time t2. The HCU <NUM>, therefore, outputs a command to the ECU <NUM> to achieve a shift to the HEV2-EV1-EV2 mode.

At time t2, the ECU <NUM> is responsive to the command from the HCU <NUM> to decrease the degree of torque produced by the engine <NUM> toward zero.

Simultaneously with when the torque produced by the engine <NUM> starts dropping, the HCU <NUM> outputs a command to the odd-numbered gear inverter <NUM> to increase the degree of torque produced by the odd-numbered gear motor generator <NUM> using the odd-numbered gear inverter <NUM> to compensate for the drop in torque produced by the engine <NUM>. In other words, the torque produced by the odd-numbered gear motor generator <NUM> is increased by the drop in torque outputted by the engine <NUM>.

At time t3 when the torque outputted by the engine <NUM> has dropped to zero, the HCU <NUM> outputs a command to the TCU <NUM> to shift the first dog-clutch <NUM> from the odd-numbered gear position to the neutral position. Simultaneously, the HCU <NUM> outputs a command to the TCU <NUM> to shift the third dog-clutch <NUM> from the second gear position to the neutral position.

The torque produced by the engine <NUM> is, as described above, kept zero at a time when the first dog-clutch <NUM> is changed from the odd-numbered gear position to the neutral position, thereby ensuring a smooth shift from the odd-numbered gear position to the neutral position of the first dog clutch <NUM>.

Similarly, the drive power exerted on the output shaft 24A of the even-numbered gear motor generator <NUM> is kept zero at a time when the third dog-clutch <NUM> is changed from the second gear position to the neutral position, thereby ensuring a smooth shift from the second gear position to the neutral position of the third dog-clutch <NUM>.

The above selected value of the drive power produced by the engine <NUM> is set to zero, but however, it is not limited thereto. For example, the selected value may be determined as an approximation thereof.

After the third dog-clutch <NUM> is shifted to the neutral position, the HCU <NUM> outputs a command to the even-numbered gear inverter <NUM> to control the torque produced by the even-numbered gear motor generator <NUM> for synchronizing or bringing the rotational speed of the input shaft <NUM> into agreement with that of the even-numbered gear intermediate shaft <NUM>.

The rotational speed of the input shaft <NUM> is controlled by the torque produced by the engine <NUM>. The rotational speed of the even-numbered gear intermediate shaft <NUM> is controlled by the torque produced by the even-numbered gear motor generator <NUM>.

The torque responsiveness of the motor generators <NUM> and <NUM> is higher than that of the engine <NUM>. The synchronization of the speed of the input shaft <NUM> with that of the even-numbered gear intermediate shaft <NUM> is, therefore, achieved by controlling the torque outputted by the even-numbered gear motor generator <NUM> to bring the speed of the even-numbered gear motor generator <NUM> close to that of the engine <NUM>, i.e., the input shaft <NUM>.

Specifically, the even-numbered gear intermediate shaft <NUM> which is rotating at the second gear ratio is driven by the even-numbered gear motor generator <NUM> to raise the speed of the even-numbered gear intermediate shaft <NUM>.

The above speed control achieves quick synchronization between the speeds of the input shaft <NUM> and the even-numbered gear intermediate shaft <NUM>.

The input shaft <NUM> is connected to the crankshaft <NUM> of the engine <NUM> in alignment therewith, so that the speed of the input shaft <NUM> is identical with that of the engine <NUM>. The HCU <NUM> analyzes an input from the crank angle sensor <NUM> (see <FIG>) to calculate the speed of the engine <NUM>. The crank angle sensor <NUM> works to measure the rotational speed of the crankshaft <NUM> of the engine <NUM>.

The speed of the even-numbered gear intermediate shaft <NUM> is calculated using the speed of the even-numbered gear motor generator <NUM>. Specifically, the drive power produced by the even-numbered gear motor generator <NUM> is decreased in speed thereof by the even-numbered motor-drive gear 51A and the even-numbered motor-driven gear 51B and then transmitted to the even-numbered gear intermediate shaft <NUM>.

The speed of the even-numbered gear intermediate shaft <NUM> is, therefore, calculated using the speed of the even-numbered gear motor generator <NUM> and gear ratios (i.e., speed reduction ratios) of the even-numbered motor-drive gear 51A and the even-numbered motor-driven gear 51B.

Similarly, the speed of the odd-numbered gear intermediate shaft <NUM> is also calculated using the speed of the odd-numbered gear motor generator <NUM> and the speed reduction ratios of the odd-numbered motor-drive gear 50A and the odd-numbered motor-driven gear 50B.

At time t4 when the speed of the input shaft <NUM> has been synchronized with that of the even-numbered gear intermediate shaft <NUM>, the HCU <NUM> outputs a command to the TCU <NUM> to shift the first dog-clutch <NUM> from the neutral position to the even-numbered gear position.

Subsequently, in order to mesh the dog teeth 54A of the third dog-clutch <NUM> with the dog teeth <NUM> of the second speed output gear 46B, the HCU <NUM> outputs a command to the even-numbered gear inverter <NUM> to control the torque produced by the even-numbered gear motor generator <NUM> which is higher in torque responsiveness than the engine <NUM> for synchronizing the speed of the second speed output gear 46B with that of the output shaft <NUM>.

Specifically, the even-numbered gear intermediate shaft <NUM> which rotates in synchronization with the input shaft <NUM> is reduced in speed by the even-numbered gear motor generator <NUM> to achieve the synchronization of the speed of the even-numbered gear intermediate shaft <NUM> with that of the output shaft <NUM>.

The speed of the output shaft <NUM> is controlled by the torque produced by the odd-numbered gear motor generator <NUM>. The speed of the second speed output gear 46B is controlled by the torque produced by the engine <NUM> and the even-numbered gear motor generator <NUM>.

After time t2, the drive power produced by the odd-numbered gear motor generator <NUM> is delivered from the odd-numbered gear intermediate shaft <NUM> to the output shaft <NUM> through the first speed gear set <NUM>, thereby keeping acceleration of the vehicle <NUM>.

In the above condition, the speeds of the output shaft <NUM>, the first speed gear set <NUM>, and the third speed gear set <NUM> may be calculated using the speed of the odd-numbered gear motor generator <NUM>, the speed reduction ratios of the odd-numbered motor-drive gear 50A and the odd-numbered motor-driven gear 50B, and the gear ratios of the first speed gear set <NUM> and the third speed gear set <NUM>.

The drive power produced by the even-numbered gear motor generator <NUM> is delivered from the even-numbered gear intermediate shaft <NUM> to the second speed gear set <NUM> or the fourth speed gear set <NUM>.

The speeds of the second speed output gear 46B and the fourth speed output gear 48B may, therefore, be calculated using the speed of the even-numbered gear motor generator <NUM>, the speed reduction ratios of the even-numbered motor-drive gear 51A and the even-numbered motor-driven gear 51B, and the gear ratios of the second speed gear set <NUM> and the fourth speed gear set <NUM>.

At time t5 when the speeds of the output shaft <NUM> and the second speed output gear 46B have become identical with each other, the HCU <NUM> shifts the position of the third dog-clutch <NUM> to the second speed output gear 46B to achieve connection of the second speed output gear 46B with the output shaft <NUM>.

The above connection of the second speed output gear 46B with the output shaft <NUM> enables the drive power produced by the engine <NUM> and the even-numbered gear motor generator <NUM> to be exerted on the output shaft <NUM>. In terms of the transmission path of the drive power produced by the engine <NUM>, the transmission <NUM> is in a state where a shift from the first gear to the second gear has been completed.

In other words, at time t5, the drive power produced by the odd-numbered gear motor generator <NUM> is transmitted from the odd-numbered gear intermediate shaft <NUM> to the output shaft <NUM> through the first speed gear set <NUM> which has the larger gear ratio (i.e., lower gear ratio), thereby causing the speed of the odd-numbered gear motor generator <NUM> to be higher than that of the even-numbered gear motor generator <NUM>. The speed of the output shaft <NUM> is identical with that of the second speed output gear 46B.

Upon completion of the shift from the first gear to the second gear in the power transmission path for the engine <NUM>, the drive power produced by the engine <NUM> is delivered from the even-numbered gear intermediate shaft <NUM> to the driven wheels <NUM> and 4R through the second speed gear set <NUM> because the first dog-clutch <NUM> is placed in the even-numbered gear position, the second dog-clutch <NUM> is placed in the first gear position, and the third dog-clutch <NUM> is placed in the second gear position.

Upon completion of the shift from the first gear to the second gear at time t5, the HCU <NUM> outputs a command to the ECU <NUM> to start executing the tasks in the HEV2-EV1-EV2 mode. The ECU <NUM> increases the drive power outputted by the engine <NUM>. Additionally, the HCU <NUM> outputs commands to the odd-numbered gear inverter <NUM> and the even-numbered gear inverter <NUM> to decrease the degrees of torque outputted by the odd-numbered gear motor generator <NUM> and the even-numbered gear motor generator <NUM>. This completes a shift to the HEV2-EV1-EV2.

The first speed gear set <NUM> is larger in gear ratio than the third speed gear set <NUM>. If, therefore, the first speed output gear 45B is kept connected to the output shaft <NUM> through the second dog-clutch <NUM> after completion of the shift from the first gear to the second gear, it will cause the speed of the odd-numbered gear motor generator <NUM> or the odd-numbered gear intermediate shaft <NUM> when the torque produced by the odd-numbered gear motor generator <NUM> is delivered to the driven wheels <NUM> and 4R through the first speed gear set <NUM> in a motor-assist mode to assist in driving the driven wheels <NUM> and 4R to be higher than that when the torque is delivered from the odd-numbered gear motor generator <NUM> to the driven wheels <NUM> and 4R through the third speed gear set <NUM>.

A loss in energy produced by the odd-numbered gear motor generator <NUM> when the torque is delivered to the driven wheels <NUM> and 4R through the first speed gear set <NUM> in the motor-assist mode is, therefore, larger than that when the torque is delivered to the driven wheels <NUM> and 4R through the third speed gear set <NUM> in the motor-assist mode.

Accordingly, the HCU <NUM> is designed to perform tasks to reduce the energy loss of the odd-numbered gear motor generator <NUM>.

Specifically, at time t5, the vehicle <NUM> is further accelerated, so that the speed of the odd-numbered gear intermediate shaft <NUM> rises. When the speed of the odd-numbered gear intermediate shaft <NUM> reaches a given value (will also be referred to as given threshold) at time t6, the HCU <NUM> starts a shift to the HEV2-EV3-EV2. The TCU <NUM> is controlled to shift the second dog-clutch <NUM> from the first gear position to the neutral position.

In the example demonstrated in <FIG>, the degree of torque produced by the odd-numbered gear motor generator <NUM> is decreased before time t6 when the speed of the odd-numbered gear intermediate shaft <NUM> reaches the given threshold, thereby facilitating the ease with which the second dog-clutch <NUM> is changed from the first gear position to the neutral position. When the odd-numbered gear motor generator <NUM> is generating the torque in the motor-assist mode or the power generation mode at time t6, the HCU <NUM> outputs a command to the odd-numbered gear inverter <NUM> to decrease the degree of torque produced by the odd-numbered gear motor generator <NUM>.

Subsequently, in order to mesh the dog teeth 53B of the second dog-clutch <NUM> with the dog teeth <NUM> of the third speed output gear 47B, the HCU <NUM> outputs a command to the odd-numbered gear motor generator <NUM> to control the torque produced thereby so as to bring the speed of the third speed output gear 47B into agreement with that of the output shaft <NUM>. Specifically, the speed of the odd-numbered gear intermediate shaft <NUM> which is rotating at a high speed following the rotation of the first speed gear set <NUM> is decreased using the odd-numbered gear motor generator <NUM> to synchronize the rotation of the third speed output gear 47B with that of the output shaft <NUM>.

When the speeds of the output shaft <NUM> and the third speed output gear 47B become equal to each other at time t7, the HCU <NUM> shifts the second dog-clutch <NUM> to the third speed output gear 47B to achieve connection of the third speed output gear 47B with the output shaft <NUM>.

In a period of time between times t6 and t7, it is impossible to transmit the drive power using the odd-numbered gear intermediate shaft <NUM>. The first dog-clutch <NUM>, however, has been shifted to the even-numbered gear position, while the third dog-clutch <NUM> has been shifted to the second gear position, thereby enabling the drive power produced by the engine <NUM> to be delivered from the even-numbered gear intermediate shaft <NUM> to the driven wheels <NUM> and 4R through the second speed gear set <NUM> to keep accelerating the vehicle <NUM>.

In other words, the drive power transmission path in which the torque is delivered from the engine <NUM> to the driven wheels <NUM> and 4R is kept in the second gear.

In the above way, the shift from the HEV1-EV1-EV2 mode to the HEV2-EV3-EV2 mode is completed.

The switch from the HEV2-EV3-EV2 mode to the HEV3-EV3-EV2 mode or from the HEV3-EV3-EV2 mode to the HEV3-EV3-EV4 mode, that is, the shift from the second gear to the third gear and the switch from the HEV3-EV3-EV4 mode to the HEV4-EV3-EV4, that is, the shift from the third gear to the fourth gear are performed in the same way as described above, and explanation thereof in detail will be omitted here.

As apparent from the above discussion, the transmission <NUM> mounted in the vehicle <NUM> in this embodiment includes the input shaft <NUM> through which the drive power produced by the engine <NUM> is transmitted, the odd-numbered gear intermediate shaft <NUM> which is arranged coaxially with the input shaft <NUM> and rotatable relative to the input shaft <NUM>, the even-numbered gear intermediate shaft <NUM> which is arranged coaxially with the input shaft <NUM>, faces the odd-numbered gear intermediate shaft <NUM> in the axial direction of the input shaft <NUM>, and is rotatable relative to the input shaft <NUM>, and the output shaft <NUM> which extend parallel to the odd-numbered gear intermediate shaft <NUM> and the even-numbered gear intermediate shaft <NUM> and transmit the drive power to the driven wheels <NUM> and 4R.

The transmission <NUM> also includes the odd-numbered gear motor generator <NUM> and the even-numbered gear motor generator <NUM>. The odd-numbered gear motor generator <NUM> is connected to the odd-numbered gear intermediate shaft <NUM> to achieve transmission of drive power therebetween. The even-numbered gear motor generator <NUM> is connected to the even-numbered gear intermediate shaft <NUM> to achieve transmission of drive power therebetween.

The transmission <NUM> also includes the first speed gear set <NUM> and the third speed gear set <NUM> which are different in gear ratio from each other and capable of connecting the odd-numbered gear intermediate shaft <NUM> to the output shaft <NUM> to achieve transmission of drive power therebetween, and the second speed gear set <NUM> and the fourth speed gear set <NUM> which are different in gear ratio from each other and capable of connecting the even-numbered gear intermediate shaft <NUM> to the output shaft <NUM>.

Further, the transmission <NUM> includes the first dog-clutch <NUM> which is switchable among the neutral position, the odd-numbered gear position where the input shaft <NUM> and the odd-numbered gear intermediate shaft <NUM> are connected together, and the even-numbered gear position where the input shaft <NUM> and the even-numbered gear intermediate shaft <NUM> are connected together.

The above structure of the transmission <NUM> is capable of shifting the gears smoothly without use of a plurality of clutches, such as in dual-clutch transmissions and enables the transmission <NUM> to be reduced in size and produced in a decreased cost.

When required to change from one of the odd-numbered gears to one of the even-numbered gears, the transmission <NUM> uses the torque produced by the odd-numbered gear motor generator <NUM> in assisting the torque output of the engine <NUM>, thereby eliminating a risk of lack of the torque output of the engine <NUM> during the gear change. Alternatively, when required to change from one of the even-numbered gears to one of the odd-numbered gears, the transmission <NUM> uses the torque produced by the odd-numbered gear motor generator <NUM> in assisting the torque output of the engine <NUM>, thereby eliminating a risk of lack of the torque output of the engine <NUM> during the gear change. This minimizes a risk of lack of ability of the engine <NUM> to accelerate the vehicle <NUM> or driver's discomfort during the acceleration of the vehicle <NUM>.

When required to change from one of the odd-numbered gears to one of the even-numbered gears, the transmission <NUM> uses the even-numbered gear motor generator <NUM> to synchronize the sped of the input shaft <NUM> with that of the even-numbered gear intermediate shaft <NUM>. Alternatively, when required to change from one of the even-numbered gears to one of the odd-numbered gears, the transmission <NUM> uses the odd-numbered gear motor generator <NUM> to synchronize the speed of the input shaft <NUM> with that of the odd-numbered gear intermediate shaft <NUM>. This eliminates the need for a complicated structure of synchronizer and also enables the transmission <NUM> to be designed to have a simple structure and produced at a decreased cost.

In this embodiment, the disturbance arising from a variation in torque output of the engine <NUM> to the gear change in the transmission <NUM> is minimized by reducing the degree of torque produced by the engine <NUM>. The synchronization of the speed of the input shaft <NUM> with that of the odd-numbered gear intermediate shaft <NUM> or the even-numbered gear intermediate shaft <NUM> is also achieved in a decreased amount of time.

The first speed gear set <NUM>, as described already, includes the first speed input gear 45A which is mounted on the odd-numbered gear intermediate shaft <NUM> to be rotatable together and the first speed output gear 45B which is mounted on the output shaft <NUM> to be rotatable relative thereto and meshes with the first speed input gear 45A. Similarly, the third speed gear set <NUM> includes the third speed input gear 47A which is mounted on the odd-numbered gear intermediate shaft <NUM> to be rotatable together and the third speed output gear 47B which is mounted on the output shaft <NUM> to be rotatable relative thereto and meshes with the third speed input gear 47A.

The second speed gear set <NUM>, as described already, includes the second speed input gear 46A which is mounted on the even-numbered gear intermediate shaft <NUM> to be rotatable together and the second speed output gear 46B which is mounted on the output shaft <NUM> to be rotatable relative thereto and meshes with the second speed input gear 46A. Similarly, the fourth speed gear set <NUM> includes the fourth speed input gear 48A which is mounted on the even-numbered gear intermediate shaft <NUM> to be rotatable together and the fourth speed output gear 48B which is mounted on the output shaft <NUM> to be rotatable relative thereto and meshes with the fourth speed input gear 48A.

The transmission <NUM> in this embodiment is also equipped with the second dog-clutch <NUM> which works to connect the first speed output gear 45B or the third speed output gear 47B to the output shaft <NUM>, so that it rotates along with the output shaft <NUM>, thereby establishing the first or third gear.

The transmission <NUM> also includes the third dog-clutch <NUM> which works to connect the second speed output gear 46B or the fourth speed output gear 48B to the output shaft <NUM>, so that it rotates along with the output shaft <NUM>, thereby establishing the second or fourth gear.

The smooth change of the multi-speed gears may, therefore, be achieved in the simple structure of the transmission <NUM> by shifting the first dog-clutch <NUM> to the odd-numbered gear position or the even-numbered gear position and then connecting one of the first speed output gear 45B to the fourth speed output gear 48B to the output shaft <NUM> through the second dog-clutch <NUM> or the third dog-clutch <NUM>. This ensures the gear change without a deterioration of drivability of the vehicle <NUM> and a lack of acceleration of the vehicle <NUM>.

The transmission <NUM> is also designed to have the odd-numbered motor-driven gear 50B which is arranged closest to the first dog-clutch <NUM> in the axial direction of the odd-numbered gear intermediate shaft <NUM> and also have the first speed input gear 45A and the third speed input gear 47A which are located on the opposite side of the odd-numbered motor-driven gear 50B to the first dog-clutch <NUM>.

The transmission <NUM> also has the even-numbered motor-driven gear 51B located closest to the first dog-clutch <NUM> in the axial direction of the even-numbered gear intermediate shaft <NUM> and also has the second speed input gear 46A and the fourth speed input gear 48A which are located on the opposite side of the even-numbered motor-driven gear 51B to the first dog-clutch <NUM>.

The odd-numbered motor-driven gear 50B, the third speed input gear 47A, and the first speed input gear 45A are arranged in order of increasing distance from the first dog-clutch <NUM> in the axial direction of the odd-numbered gear intermediate shaft <NUM> and also have diameters decreasing in this order.

Similarly, the even-numbered motor-driven gear 51B, the fourth speed input gear 48A, and the second speed input gear 46A are arranged in order of increasing distance from the first dog-clutch <NUM> in the axial direction of the even-numbered gear intermediate shaft <NUM> and also has diameters decreasing in this order.

The above arrangements enable the odd-numbered gear motor generator <NUM> to be disposed to overlap the first speed input gear 45A and the third speed input gear 47A in a direction perpendicular to the axis of the odd-numbered gear intermediate shaft <NUM> in order to locate the odd-numbered gear motor generator <NUM> close to the odd-numbered gear intermediate shaft <NUM>.

The above arrangements also enable the even-numbered gear motor generator <NUM> to be disposed to overlap the second speed input gear 46A and the fourth speed input gear 48A in a direction perpendicular to the axis of the even-numbered gear intermediate shaft <NUM> in order to locate the even-numbered gear motor generator <NUM> close to the even-numbered gear intermediate shaft <NUM>. This enables the transmission <NUM> to be reduced in size thereof.

The transmission <NUM> has the first speed gear set <NUM> and the third speed gear set <NUM> designed as gear sets which are mounted on the odd-numbered gear intermediate shaft <NUM> and the output shaft <NUM>, respectively, and have odd gear ratios different from each other. The transmission <NUM> also has the second speed gear set <NUM> and the fourth speed gear set <NUM> designed as gear sets which are mounted on the even-numbered gear intermediate shaft <NUM> and the output shaft <NUM>, respectively, and have even gear ratios different from each other.

Accordingly, when required to change from one of the odd gear ratios to one of the even gear ratios, the transmission <NUM> works to decrease the degree of torque produced by the engine <NUM> down to zero, increase the degree of torque produced by the odd-numbered gear motor generator <NUM> to compensate for a drop in torque outputted by the engine <NUM>, synchronize the speed of the even-numbered gear intermediate shaft <NUM> with that of the input shaft <NUM>, and then shift the first dog-clutch <NUM> to the even-numbered gear position.

Alternatively, when required to change from one of the even gear ratios to one of the odd gear ratios, the transmission <NUM> works to decrease the degree of torque produced by the engine <NUM> down to zero, increase the degree of torque produced by the even-numbered gear motor generator <NUM> to compensate for a drop in torque outputted by the engine <NUM>, synchronize the speed of the odd-numbered gear intermediate shaft <NUM> with that of the input shaft <NUM>, and then shift the first dog-clutch <NUM> to the odd-numbered gear position.

The above control ensures the stability in achieving the gear change from one the odd gears to one of the even gears or vice versa, thereby eliminating the risk of deterioration of drivability of the vehicle <NUM>.

The transmission <NUM> in this embodiment is also designed to have the first dog-clutch <NUM>, the second dog-clutch <NUM>, and the third dog-clutch <NUM> which serve as switching members, thereby achieving the gear change using the first dog-clutch <NUM>, the second dog-clutch <NUM>, and the third dog-clutch <NUM> without use of synchronizers which are more complex in mechanism than the first dog-clutch <NUM>, the second dog-clutch <NUM>, and the third dog-clutch <NUM>. This enables the transmission <NUM> to have a simplified structure and also to be produced at a decreased cost.

The first dog-clutch <NUM> is capable of achieving quick and smooth connection of the input shaft <NUM> and the odd-numbered gear intermediate shaft <NUM> at a time when the speed of the input shaft <NUM> is synchronized with that of the odd-numbered gear intermediate shaft <NUM>.

Additionally, the first dog-clutch <NUM>, the second dog-clutch <NUM>, and the third dog-clutch <NUM> are designed to have simplified structures, thereby resulting in improvement of durability thereof, which enables them to be used for an increased period of time.

The vehicle <NUM> is equipped with the coupling <NUM> which is made of a damper and connects the engine <NUM> with the input shaft <NUM> at all times to deliver the torque from the engine <NUM> to the input shaft <NUM>.

When required to shift the gears, the transmission <NUM> use the odd-numbered gear motor generator <NUM> or the even-numbered gear motor generator <NUM> to bring the speed of the input shaft <NUM> into agreement with that of the odd-numbered gear intermediate shaft <NUM> or the even-numbered gear intermediate shaft <NUM>, thereby ensuring the stability in connecting the odd-numbered gear intermediate shaft <NUM> or the even-numbered gear intermediate shaft <NUM> with the input shaft <NUM> through the first dog-clutch <NUM>. This eliminates the need for a clutch used to connect or disconnect the engine <NUM> to or from the input shaft <NUM>.

The above arrangements enable the coupling <NUM> which is made of a small-sized and inexpensive damper to be used instead of the clutch device, which permits the transmission <NUM> to be reduced in size and produced at a decreased cost.

The coupling <NUM> may alternatively be implemented by a clutch device working to connect or disconnect the engine <NUM> to or from the input shaft <NUM>.

The connect or disconnect of the engine <NUM> to or from the input shaft <NUM> using the clutch device, as referred to herein, means the fact that when it is required to deliver torque from the engine <NUM> to the input shaft <NUM>, the clutch device mechanically connects the crankshaft <NUM> of the engine <NUM> with the input shaft <NUM>, or alternatively, when it is not required to deliver torque from the engine <NUM> to the input shaft <NUM>, the clutch device mechanically disconnect the crankshaft <NUM> of the engine <NUM> from the input shaft <NUM>.

The use of the above clutch device enables the transmission of torque from the engine <NUM> to the input shaft <NUM> to be mechanically blocked when it is required to change the gears in the transmission <NUM>, thereby permitting the odd-numbered gear motor generator <NUM> or the even-numbered gear motor generator <NUM> to be used to synchronize the speed of the input shaft <NUM> with that of the odd-numbered gear intermediate shaft <NUM> or the even-numbered gear intermediate shaft <NUM> quickly. This achieves quick gear shifts in the transmission <NUM>.

The transmission <NUM> is, as described above, designed to have the odd-numbered gear intermediate shaft <NUM> and the output shaft <NUM> which are connectable together using the first speed gear set <NUM> or the third speed gear set <NUM>. The transmission <NUM> is also designed to have the even-numbered gear intermediate shaft <NUM> and the output shaft <NUM> which are connectable together using the second speed gear set <NUM> or the fourth speed gear set <NUM>. Such a structure may, however, be optically altered.

Claim 1:
A hybrid vehicle (<NUM>) equipped with a transmission (<NUM>) working to transmit drive power produced by an internal combustion engine (<NUM>) to a driven wheel (<NUM>, 4R) and change a speed of the drive power, wherein
the transmission comprises:
an input shaft (<NUM>) to which drive power produced by the internal combustion engine is transmitted;
a first intermediate shaft (<NUM>) which is arranged coaxially with the input shaft and rotatable relative to the input shaft, the first intermediate shaft having the input shaft extending inside the first intermediate shaft;
a second intermediate shaft (<NUM>) which is arranged coaxially with the input shaft, aligned with the first intermediate shaft in an axial direction of the input shaft, and rotatable relative to the input shaft, the second intermediate shaft having the input shaft extending inside the second intermediate shaft;
an output shaft (<NUM>) which extends parallel to the first intermediate shaft and the second intermediate shaft and serves to deliver the drive power to the driven wheel;
a first rotating electrical machine (<NUM>) which is connected to the first intermediate shaft to transmit drive between the first rotating electrical machine and the first intermediate shaft;
a second rotating electrical machine (<NUM>) which is connected to the second intermediate shaft to transmit drive power between the second rotating electrical machine and the second intermediate shaft;
first gear sets (<NUM>, <NUM>) each of which works to connect the first intermediate shaft with the output shaft to transmit drive power therebetween and which establish a plurality of gears in the transmission which are different in gear ratio from each other;
second gear sets (<NUM>, <NUM>) each of which works to connect the second intermediate shaft with the output shaft to transmit drive power therebetween and which establish a plurality of gears in the transmission which are different in gear ratio than those of the first gear sets; and
a first switching member (<NUM>) which works to switch among a neutral position, a first position, and a second position, the first position being to achieve connection of the input shaft and the first intermediate shaft, the second position being to achieve connection of the input shaft and the second intermediate shaft, and wherein
the first switching member is disposed between the first intermediate shaft and the second intermediate shaft in the axial direction of the input shaft.