Control device for vehicular power transmitting apparatus

A control device for a vehicle which includes a differential portion controlling a differential state between the number of rotations of an input shaft connected to an engine, and the number of rotations of an output shaft connected to drive wheels, with controlling an operating state of an electric motor, and an automatic shifting portion forming part of a power transmitting path. The control device prevents degradation in operability of the vehicle, even in the presence of a shifting command resulting from a manual shift operation when the automatic shifting portion remains under a limited shifting state. More particularly, if the shifting command is present due to the manual shift operation, the differential state of the differential portion is controlled, thereby causing a variation in a drive force at a rate corresponding to the shifting command.

BACKGROUND OF THE INVENTION

1. Field of the invention

This invention relates to a control device for a vehicular power transmitting apparatus. The vehicular power transmitting apparatus includes an electrically controlled differential portion and a shifting portion forming part of a power transmitting path. The electrically controlled differential portion controls a differential state between the number of rotations of an input shaft connected to an internal combustion engine, and the number of rotations of an output shaft connected to drive wheels, with controlling an operating state of an electric motor connected to a rotary element of a differential portion in power trasmissive state. More particularly, the present invention relates to a technology related to the control device for ensuring a variation in drive force during a manual shift operation with the shifting portion remaining under a disabled shifting state.

2. Description of the Related Art

There has been known a vehicular power transmitting apparatus including an electrically controlled differential portion controlling a differential state between the number of rotations of an input shaft connected to an internal combustion engine, and the number of rotations of an output shaft connected to drive wheels, with controlling an operating state of an electric motor connected to a rotary element of a differential portion in power trasmissive state, and a shifting portion forming part of a power transmitting path. For instance, Patent Publication 1 (Japanese Patent Application Publication No. 2005-264762) discloses such a vehicular power transmitting apparatus. With the vehicular power transmitting apparatus disclosed in Patent Publication 1, regeneration-efficiency optimizing control means controls during a coast running condition a speed ratio of an automatic shifting portion to optimize regeneration efficiency to thereby accomplish improved fuel consumption.

By the way, when requiring a drive force or an engine bake force for a vehicle, driver usually performs a manual shift operation to effectuate, for instance, a downshift in the vehicular power transmitting apparatus. However, the shifting is restricted or limited due to various factors such as a disabled shifting state caused by a failure or another disabled shifting state resulting from an overspeed rotation or the like. For instance, the shift portion encounters a difficulty of switching a gear position or a speed ratio. In such likelihood, no decelerating drive force (engine brake) can be obtained, resulting in a probability with the occurrence of degraded operability of the vehicle.

SUMMARY OF THE INVENTION

The present invention has been completed with the above views in mind, and has an object to provide a control device for a vehicular power transmitting apparatus. The vehicular power transmitting apparatus has an electrically controlled differential portion controlling a differential state between the number of rotations of an input shaft connected to an internal combustion engine, and the number of rotations of an output shaft connected to drive wheels, with controlling an operating state of an electric motor connected to a rotary element of a differential portion in power trasmissive state, and a shifting portion forming part of a power transmitting path. The control device provides no degraded operability of a vehicle in the presence of a shifting command even if the shifting portion remains under a restricted i.e. limited shifting state.

For achieving the above object, a first aspect of the present invention, related to a control device for a vehicular power transmitting apparatus, is featured by that the vehicular power transmitting apparatus comprises an electrically controlled differential portion controlling a differential state between the number of rotations of an input shaft connected to a drive-force generating engine, and the number of rotations of an output shaft connected to drive wheels, with controlling an operating state of an electric motor connected to a rotary element of a differential portion, and a shifting portion forming part of a power transmitting path.

Also, the first aspect is featured by that the control device is operative to control the differential state of the electrically controlled differential portion in the presence of a shifting command when the shifting portion remains under a limited shifting, for thereby causing a variation in a drive force at a rate corresponding to the shifting command.

In a second aspect, the shifting command is generated in response to a shifting operation of a driver.

In a third aspect, the control device varies the number of rotations of the drive-force generating engine for thereby controlling the differential state of the electrically controlled differential portion.

In a fourth aspect, the control device varies a power generating state of the electric motor for thereby controlling the differential state of the electrically controlled differential portion.

In a fifth aspect, the control device selectively alters the number of rotations of the drive-force generating engine or alters the power generating state of the electric motor depending on a charged sate of a battery for thereby controlling the differential state of the electrically controlled differential portion.

In a sixth aspect, the control device selectively alters the number of rotations of the drive-force generating engine or alters the power generating state of the electric motor depending on a state of the drive-force generating engine for thereby controlling the differential state of the electrically controlled differential portion.

In a seventh aspect, the shifting portion of the vehicular power transmitting apparatus comprises a mechanical type transmission that varies a speed ratio with varying a torque transmitting path.

In a eighth aspect, the electrically controlled differential portion of the vehicular power transmitting apparatus operates to serve as a continuously variable transmission with controlling an operating state of the electric motor.

With the control device for a vehicular power transmitting apparatus of the first aspect, if the shifting command is present when the shifting portion remains under the restricted i.e. limited shifting state, the control device operates to control the differential state of the electrically controlled differential portion. This allows the drive force to be generated at a varying rate in line with the shifting command, which appropriately prevents the occurrence of degradation in operability of the vehicle.

With the control device for a vehicular power transmitting apparatus of the second aspect, the shifting command is generated in response to the shifting operation of the driver. This enables the drive force to be generated at the varying rate in line with the shifting command of the driver, appropriately preventing the occurrence of degradation in operability of the vehicle.

With the control device for a vehicular power transmitting apparatus in the third aspect, the control device varies the number of rotations of the drive-force generating engine for thereby controlling the differential state of the electrically controlled differential portion. Thus, varying the number of rotations of the drive-force generating engine allows the drive force to vary in line with the shifting command.

With the control device for a vehicular power transmitting apparatus of the fourth aspect, the control device varies the power generating state of the electric motor for thereby controlling the differential state of the electrically controlled differential portion. Thus, varying the power generating state of the electric motor allows the drive force to vary in line with the shifting command.

With the control device for a vehicular power transmitting apparatus of a fifth aspect, the control device selectively alters the number of rotations of the drive-force generating engine or alters the power generating state of the electric motor, depending on a charge state of a battery for thereby controlling the differential state of the electrically controlled differential portion. Thus, selectively altering the number of rotations of the drive-force generating engine or altering the power generating state of the electric motor depending on the charged sate of the battery, allows the drive force to vary in line with the shifting command.

With the control device for a vehicular power transmitting apparatus of the sixth aspect, the control device selectively alters the number of rotations of the drive-force generating engine or alters the power generating state of the electric motor, depending on the state of the drive-force generating engine for thereby controlling the differential state of the electrically controlled differential portion. Therefore, selectively altering the number of rotations of the drive-force generating engine or altering the power generating state of the electric motor depending on the state of the drive-force generating engine, allows the drive force to vary in line with the shifting command regardless the power generating state of the drive-force generating engine.

With the control device for a vehicular power transmitting apparatus of the seventh aspect, the shifting portion comprises the mechanical type transmission that varies the speed ratio with varying the torque transmitting path. Therefore, rendering the electrically controlled differential portion operative as the continuously variable transmission allows a whole of the vehicular power transmitting apparatus to infinitely vary the speed ratio, thereby obtaining the drive force in a continuously variable fashion.

With the control device for a vehicular power transmitting apparatus of the eighth aspect, the electrically controlled differential portion of the vehicular power transmitting apparatus operates to serve as the continuously variable transmission with controlling the operating state of the electric motor, enabling drive torque to smoothly vary. In addition, the electrically controlled differential portion not only has a function to operate as an electrically controlled continuously variable transmission with the speed ratio being continuously varied, but also has a function to operate as a step-variable transmission with varying the speed ratio step-by-step.

Preferably, the rotary element of the differential portion includes a planetary gear unit having three rotary elements involving a first rotary element connected to the input shaft and the engine, a second rotary element connected to the first electric motor, and a third rotary element connected to the output shaft. The first rotary element includes a carrier of the planetary gear unit; the second rotary element includes a sun gear of the planetary gear unit; and the third rotary element includes ring gear of the planetary gear unit. With such a structure, the differential mechanism can have a minimized dimension in an axial direction. In addition, the differential mechanism can be simply structured with one planetary gear unit.

More preferably, the planetary gear unit includes a single pinion type planetary gear unit. With such a structure, the differential mechanism can have a minimized dimension in an axial direction. In addition, the differential mechanism can be simply structured with one single pinion type planetary gear unit.

More preferably, the vehicular power transmitting apparatus provides an overall speed ratio that is established based on the speed ratio (gear ratio) of the shifting portion and the speed ratio of the electrically controlled differential portion. With such a structure, utilizing the speed ratio of the shifting portion allows the drive force to be obtained in a wide range.

More preferably, the shifting portion includes a step-variable planetary gear type automatic power transmission. With such a structure, the continuously variable transmission can be structured with the electrically controlled differential portion, rendered operative as, for instance, the electrically controlled continuously variable transmission, and the step-variable type automatic power transmission, thereby making it possible to smoothly vary the drive torque. In addition, with the electrically controlled differential portion held in a controlled state to keep a constant speed ratio, the electrically controlled differential portion and the step-variable type automatic power transmission establish a state, equivalent to the step-variable transmission. This enables the vehicular power transmitting apparatus to have the overall speed ratio that can be varied step-by-step to rapidly obtain drive torque.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, various embodiments according to the present invention will be described below in detail with reference to the accompanying drawings.

Embodiment

FIG. 1is a skeleton diagram for illustrating a transmission mechanism i.e., shifting mechanism10constituting a part of a power transmitting apparatus for a hybrid vehicle to which the present invention is applied. As shown inFIG. 1, the transmission mechanism10includes a transmission case12(hereinafter referred to as “a case12”) mounted on a vehicle body as a non-rotary member, an input shaft14disposed inside the case12as an input rotary member, a differential portion11coaxially connected to the input shaft14either directly, or indirectly via a pulsation absorbing damper (vibration damping device), not shown, and serving as a continuously variable transmission portion, an automatic transmission portion20connected in series in a power transmitting path between the differential portion11and drive wheels34(seeFIG. 7) through a power transmitting member18(power transmitting shaft), and an output shaft22connected to the automatic transmission portion20and serving as an output rotary member.

The transmission mechanism10is suitably applied to an FR (front-engine and reverse-drive) type vehicle and mounted on a vehicle along a fore and aft direction thereof. The transmission mechanism10is disposed between an engine8and a pair of drive wheels34. The engine8includes an internal combustion engine such as a gasoline engine or a diesel engine or the like and serves as a drive-power source. The engine8is directly connected to the input shaft12in series or indirectly through the pulsation absorbing damper (vibration damping device), not shown. This allows a vehicle drive force to be transferred from the engine8to the pair of drive wheels34in sequence through a differential gear device32(final speed reduction gear) (seeFIG. 7) and a pair of drive axles.

With the transmission mechanism10of the illustrated embodiment, the engine8and the differential portion11are directly connected to each other. As used herein, the term “directly connected to each other” refers to a structure under which a direct connection is established between the associated component parts in the absence of a fluid-operated power transmitting device, such as a torque converter or a fluid coupling device or the like, and a connection including, for instance, the pulsation absorbing damper is involved in such a direction connection. It is noted that a lower half of the transmission mechanism10, which is constructed symmetrically with respect to its axis, is omitted inFIG. 1. This is also true for the other embodiments of the invention described below.

The differential portion11includes a first electric motor M1, a power distributing mechanism16, structured in a mechanical mechanism for mechanically distributing an output of the engine8applied to the input shaft14, which functions as a differential mechanism through which the engine output is distributed to the first electric motor M1and the power transmitting member18, and a second electric motor M2operatively connected to the power transmitting member18to be unitarily rotate therewith. In the illustrated embodiment, both the first and second electric motors M1and M2are so-called motor/generators each having a function to generate electric power. The first electric motor M1has at least a function as an electric power generator for generating a reaction force. The second electric motor M2has at least a function as a motor (electric motor) serving as a running drive power source to output a vehicle drive force.

The power distributing mechanism16includes, as a major component, a first planetary gear set24of a single pinion type having a gear ratio ρ1of about 0.418, for example. The first planetary gear set24has rotary elements (elements) composed of a first sun gear S1, a first planetary gear P1, a first carrier CA1supporting the first planetary gear P1such that the first planetary gear P1is rotatable about its axis and about the axis of the first sun gear S1, and a first ring gear R1meshing with the first sun gear S1through the first planetary gear P1. Where the numbers of teeth of the first sun gear S1and the first ring gear R1are represented by ZS1and ZR1, respectively, the above gear ratio ρ1is represented by ZS1/ZR1.

With the power distributing mechanism16, a first carrier CA1is connected to the input shaft14, i.e., the engine8; a first sun gear S1is connected to the first electric motor M1; and a first ring gear R1is connected to the power transmitting member18. With the power distributing mechanism16of such a structure, the three elements of the first planetary gear set24, i.e., the first sun gear S1, the first planetary gear P1, the first carrier CA1and the first ring gear R1are arranged to rotate relative to each other for initiating a differential action, i.e., in a differential state under which the differential action is initiated. This allows the engine output to be distributed to the first electric motor M1and the power transmitting mechanism18. Then, a part of the distributed engine output drives the first electric motor M1to generate electric energy, which is stored and used for rotatably driving the second electric motor M2.

Thus, the differential portion11(power distributing mechanism16) is caused to function as an electric differential device such that, for instance, the differential portion11is placed in a so-called continuously variable shifting state (electrically established CVT state) to continuously vary the rotation of the power transmitting member18regardless of the engine8operating at a given rotational speed. That is, the differential portion11functions as an electrically controlled continuously variable transmission to provide a speed ratio γ0(rotational speed NINof the input shaft14/rotational speed N18of the power transmitting member18) that is continuously variable from a minimum value γ0min to a maximum value γ0max. In this way, the first electric motor M1, the second electric motor M2and the engine8all connected to the power distributing mechanism16(differential portion11) are controlled in the driving conditions thereof, so that the differential state of the rotation speeds i.e. rotational speeds of the input shaft14and the transmitting member18is controlled.

The automatic transmission portion20includes a single-pinion type second planetary gear set26, a single-pinion type third planetary gear set28and a single-pinion type fourth planetary gear set30. The automatic transmission portion20is a planetary gear type multiple-step transmission operable as a step-variable automatic transmission. The second planetary gear set26has a second sun gear S2; a second planetary gear P2; a second carrier CA2supporting the second planetary gear P2such that the second planetary gear P2is rotatable about its axis and about the axis of the second sun gear S2; and a second ring gear R2meshing with the second sun gear S2through the second planetary gear P2. For example, the second planetary gear set26has a given gear ratio ρ2of about “0.562”. The third planetary gear set28has a third sun gear S3; a third planetary gear P3; a third carrier CA3supporting the third planetary gear P3such that the third planetary gear P3is rotatable about its axis and about the axis of the third sun gear S3; and a third ring gear R3meshing with the third sun gear S3through the third planetary gear P3. For example, the third planetary gear set28has a given gear ratio ρ3of about “0.425”.

The fourth planetary gear set30has: a fourth sun gear S4; a fourth planetary gear P4; a fourth carrier CA4supporting the fourth planetary gear P4such that the fourth planetary gear P4is rotatable about its axis and about the axis of the fourth sun gear S4; and a fourth ring gear R4meshing with the fourth sun gear S4through the fourth planetary gear P4. For example, the fourth planetary gear set30has a given gear ratio ρ4of, for instance, about “0.421”. With the second sun gear S2, second ring gear R2, third sun gear S3, third ring gear R3, fourth sun gear S4and fourth ring gear R4having the numbers of gear teeth represented by ZS2, ZR2, ZS3, ZR3, ZS4and ZR4, respectively, the gear ratios ρ2, ρ3and ρ4are expressed by ZS2/ZR2, ZS3/ZR3, and ZS4/ZR4, respectively.

In the automatic transmission portion20, the second and third sun gears S2, S3are integrally connected to each other, selectively connected to the power transmitting member18through a second clutch C2, and selectively connected to the casing12through a first brake B1. The second carrier CA2is selectively connected to the casing12through a second brake B2, and the fourth ring gear R4is selectively connected to the casing12through a third brake B3. The second ring gear R2, third carrier CA3and fourth carrier CA4are integrally connected to each other and connected to the output shaft22. The third ring gear R3and the fourth sun gear S4are integrally connected to each other and selectively connected to the power transmitting member18through a first clutch C1.

Thus, the automatic transmission portion20and the differential portion11(power transmitting member18) are selectively connected to each other through the first clutch C1or the second clutch C2, which is provided to establish each gear position (shift gear position) in the automatic transmission portion20. In other words, the first and second clutches C1, C2function as coupling devices i.e., engaging device operable to place the power transmitting path between the power transmitting member18and the automatic transmission portion20, that is, the power transmitting path between the differential portion11(power transmitting member18) and the drive wheels34, selectively in one of a power transmitting state in which the vehicle drive force can be transmitted through the power transmitting path, and the power cut-off state in which the vehicle drive force cannot be transmitted through the power transmitting path. That is, with at least one of the first and second clutches C1and C2brought into coupling engagement, the power transmitting path is placed in the power transmitting state. In contrast, uncoupling both the first and second clutches C1and C2places the power transmitting path in the power cut-off state.

With the automatic transmission portion20, further, uncoupling an on-uncoupling coupling device while coupling an on-coupling coupling device allows a so-called “clutch-to-clutch” shifting action to be executed for respective gear positions to be selectively established. This allows a speed ratio γ (rotational speed N18of the power transmitting member18/rotational speed NOUTof the output shaft22) to be obtained in equally varying ratio for each gear position. As indicated in the coupling operation table shown inFIG. 2, coupling the first clutch C1and third brake B3establishes 1st-speed gear position having a speed ratio γ1of approximately, for instance, “3.357”.

With the first clutch C1and second brake B3coupled in operation, a 2nd-speed gear position is established with a speed ratio γ2of, for instance, approximately “2.180”, which is lower a value of the speed ratio γ1. With the first clutch C1and first brake B1coupled in operation, a 3rd-speed gear position is established with a speed ratio γ3of, for instance, approximately “1.424”, which is lower a value of the speed ratio γ2. Coupling the first clutch C1and second clutch C2establishes a 4th-speed gear position with a speed ratio γ4of, for instance, approximately “1.000”, which is lower than the speed ratio γ3. Coupling the second clutch C2and third brake B3establishes a reverse-drive gear position (reverse-drive shift position) with a speed ratio γR of, for instance, approximately 3.209, which is intermediate between those of the 1st-speed gear position and the 2nd-speed gear position. In addition, uncoupling i.e., disengaging or releasing the first clutch C1, second clutch C2, first brake B1, second brake B2and third brake B3allows a neutral position N to be established.

The first clutch C1, second clutch C2, first brake B1, second brake B2and third brake B3(hereinafter collectively referred to as clutch C and brake B, unless otherwise specified) are hydraulically operated frictional coupling devices that are used in the related art vehicular automatic transmission. Each of these frictional coupling devices may include a wet-type multiple-disc clutch, having a plurality of mutually overlapping friction plates adapted to be pressurized against each other by a hydraulic actuator, or a band brake including a rotary drum having an outer circumferential surface on which one band or two bands are wound with terminal ends being adapted to be tightened by a hydraulic actuator. Thus, the frictional coupling device serves to selectively provide a drive connection between two component parts between which each clutch or brake is interposed.

With the transmission mechanism10of such a structure, the differential portion11, serving as the continuously variable transmission, and the automatic transmission portion20constitute a continuously variable transmission. Further, with the differential portion11controlled so as to provide a speed ratio kept at a fixed level, the differential portion11and the automatic transmission portion20can provide the same state as that of a step-variable transmission.

More particularly, the differential portion11functions as the continuously variable transmission and the automatic transmission portion20, connected to the differential portion11in series, functions as the step-variable transmission. Thus, the rotational speed, input to the automatic transmission portion20placed for at least one gear position M, (hereinafter referred to as “input rotational speed of the automatic transmission portion20”), i.e., the rotational speed of the power transmitting member18(hereinafter referred to as “transmitting-member rotational speed N18”) are caused to continuously vary, thereby enabling the gear position M to have a continuously variable speed range. Accordingly, the transmission mechanism10provides an overall speed ratio γT (=rotational speed NINof the input shaft14/rotational speed NOUTof the output shaft22) in a continuously variable range. Thus, the continuously variable transmission is established in the transmission mechanism10. The overall speed ratio γT of the transmission mechanism10is the total speed ratio γT of a whole of the automatic transmission portion20that is established based on the speed ratio γ0of the differential portion11and the speed ratio γ of the automatic transmission portion20.

For the respective gear positions such as, for instance, the 1st-speed to 4th-speed gear positions of the automatic transmission portion20and the reverse-drive gear position as indicated in the coupling operation table shown inFIG. 2, the transmitting-member rotational speed N18is continuously varied with each gear position being obtained in a continuously variable speed range. Accordingly, a continuously variable speed ratio is present between adjacent gear positions, enabling the whole of the transmission mechanism10to have the total speed ratio γT in a continuously variable range.

Further, the speed ratio γ0of the differential portion11is controlled so as to lay at a fixed level and the clutch C and brake B are selectively coupled, thereby causing either one of the 1st-speed to 4th-speed gear positions or the reverse-drive gear position (reverse-drive shift position) to be selectively established. This allows the overall speed ratio γT, variable in a nearly equal ratio, of the transmission mechanism10to be obtained for each gear position. Thus, the transmission mechanism10can be established in the same state as that of the step-variable transmission.

If, for instance, the differential portion11is controlled so as to provide the speed ratio γ0at a fixed value of “1”, the transmission mechanism10provides the total speed ratio γT for each gear position of the 1st-speed to 4th-speed gear positions of the automatic transmission portion20and the reverse-drive gear position as indicated by the coupling operation table shown inFIG. 2. Further, if the automatic transmission portion20is controlled under the 4th-speed gear position so as to cause the differential portion11to have the speed ratio γ0of approximately, for instance, “0.7” less than a value of “1”, the automatic transmission portion20has the total speed ratio γT of approximately, for instance, “0.7” that is less than a value of the 4th-speed gear position.

FIG. 3is a collinear chart for the transmission mechanism10, including the differential portion11and the automatic transmission portion20, wherein the relative motion relationships among the rotational speeds of the various rotary elements in different coupling states for each gear position can be plotted on straight lines. The collinear chart ofFIG. 3takes the form of a two-dimensional coordinate system having the abscissa axis plotted with the gear ratios p of the planetary gear sets24,26,28,30and the ordinate axis plotted with the mutually relative rotating speeds of the rotary elements. A transverse line X1indicates the rotational speed that is zeroed; a transverse line X2the rotational speed of “1.0”, that is, the rotating speed NEof the engine8connected to the input shaft14; and a transverse line XG the rotational speed of the power transmitting member18.

Starting from the left, three vertical lines Y1, Y2and Y3, associated with the three elements of the power distributing mechanism16forming the differential portion11, represent the mutually relative rotating speeds of the first sun gear S1corresponding to a second rotary element (second element) RE2, the first carrier CA1corresponding to a first rotary element (first element) RE1, and the first ring gear R1corresponding to a third rotary element (third element) RE3, respectively. A distance between the adjacent vertical lines is determined based on the gear ratio ρ1of the first planetary gear set24.

Starting from the left, further, five vertical lines Y4, Y5, Y6, Y7and Y8for the automatic transmission portion20represent the mutually relative rotating speeds of: the second and third sun gears S2, S3, connected to each other, which corresponds to a fourth rotary element (fourth element) RE4; the second carrier CA2corresponding to a fifth rotary element (fifth element) RE5; the fourth ring gear R4acorresponding to a sixth rotary element (sixth element) RE6; the second ring gear R2, third carriers CA3and fourth carriers CA4, connected to each other, which correspond to a seventh rotary element (seventh element) RE7; and the third ring gear R3and fourth sun gear S4connected to each other and corresponding to an eighth rotary element (eighth element) RE8, respectively. Each distance between the adjacent vertical lines is determined based on the gear ratios ρ2, ρ3and ρ4of the second, third and fourth planetary gear sets26,28,30.

In the relationship among the vertical lines on the collinear chart, if a space between the sun gear and carrier is set to a distance corresponding to a value of “1”, then, a space between the carrier and ring gear lies at a distance corresponding to the gear ratio p of the planetary gear set. That is, for the differential portion11, a space between the vertical lines Y1and Y2is set to a distance corresponding to a value of “1” and a space between the vertical lines Y2and Y3is set to a distance corresponding to the gear ratio ρ1. For the automatic transmission portion20, further, the space between the sun gear and carrier is set to the distance corresponding to the value of “1” for each of the second, third and fourth planetary gear sets26,28,30, for which the space between the carrier and ring gear is set to the distance corresponding to the gear ratio ρ1.

Referring to the collinear chart ofFIG. 3, the power distributing mechanism16(differential portion11) of the transmission mechanism10is arranged such that the first rotary element RE1(first carrier CA1) of the first planetary gear set24is connected to the input shaft14, i.e., the engine8and the second rotary element RE2is connected to the first electric motor M1. The third rotary element RE3(first ring gear R1) is connected to the power transmitting member18and the second electric motor M2. Thus, a rotary motion of the input shaft14is transmitted (input) to the automatic transmission portion20through the power transmitting member18. A relationship between the rotational speeds of the first sun gear S1and the first ring gear R1is represented by an inclined straight line L0which passes across a point of intersection between the lines Y2and X2.

Now, description is made of a case in which, for example, the differential portion11is placed in a differential state with the first to third rotary elements RE1to RE3enabled to rotate relative to each other while the rotational speed of the first ring gear R1, indicated at an intersecting point between the straight line L0and the vertical line Y1, is bound with the vehicle speed V and remains at a nearly constant level. In this case, as the engine speed NEis controlled with the rotational speed of the first carrier CA1, as represented by an intersecting point between the straight line L0and the vertical line Y2, being raised or lowered, the rotational speed of the first sun gear S1, i.e., the rotational speed of the first electric motor M1, indicated by an intersecting pint between the straight line L0and the vertical line Y1, is raised or lowered.

On controlling the rotational speed of the first electric motor M1so as to allow the differential portion11to have the speed ratio γ0of “1” with the first sun gear S1rotating at the same speed as the engine speed NE, the straight line L0is aligned with the horizontal line X2. When this takes place, the first ring gear R1, i.e., the power transmitting member18, is caused to rotate at the same speed as the engine speed NE. On the contrary if the rotational speed of the first electric motor M1is controlled so as to allow the differential portion11to have the speed ratio γ0of a value less than “1”, for instance, a value of approximately “0.7” with the rotational speed of the first sun gear S1being zeroed, the power transmitting member18is caused to rotate at an increased transmitting-member rotational speed N18higher than the engine speed NE.

With the automatic transmission portion20, the fourth rotary element RE4is selectively connected to the power transmitting member18via the second clutch C2and selectively connected to the casing12via the first brake B1with the fifth rotary element RE5being selectively connected to the casing12via the second brake B2. The sixth rotary element RE6is selectively connected to the casing12via the third brake B3with the seventh rotary element RE7connected to the output shaft22, and the eighth rotary element RE8is selectively connected to the power transmitting member18via the first clutch C1.

Next, description is made of a case wherein with the automatic transmission portion20, the differential portion,11is placed in a state with the straight line L0brought into coincidence with the horizontal line X2to cause the differential portion11to transfer the vehicle drive force to the eighth rotary element RE8at the same speed as the engine speed NEupon which the first clutch C1and the third brake B3are coupled as shown inFIG. 3. In this case, the rotational speed of the output shaft22for the 1st-speed gear position is represented by an intersecting point between the inclined line L1, passing across an intersecting point between the vertical line Y8, indicative of the rotational speed of the eighth rotary element RE8, and the horizontal line X2and a point of intersection between the vertical line Y6, indicative of the rotational speed of the sixth rotary element RE6, and the horizontal line X1, and an intersecting point intersecting the vertical line Y7indicative of the rotational speed of the seventh rotary element RE connected to the output shaft22as indicated inFIG. 3.

Similarly, the rotational speed of the output shaft22for the 2nd-speed gear position is represented by an intersecting point between an inclined straight line L2, determined when the first clutch C1and second brake B2are coupled, and the vertical line Y7indicative of the rotational speed of the seventh rotary element RE7connected to the output shaft22. The rotational speed of the output shaft22for the 3rd-speed gear position is represented by an intersecting point between an inclined straight line L3, determined with the first clutch C1and first brake B1being coupled, and the vertical line Y7indicative of the rotational speed of the seventh rotary element RE7connected to the output shaft22. The rotational speed of the output shaft22for the 4th-speed gear position is represented by an intersecting point between a horizontal straight line L4, determined with the first clutch C1and second brake B2being coupled, and the vertical line Y7indicative of the rotational speed of the seventh rotary element RE7connected to the output shaft22.

FIG. 4shows an electronic control unit80operative to control the transmission mechanism10of the present invention for generating various output signals in response to various input signals. The electronic control unit80includes a so-called microcomputer incorporating a CPU, a ROM, a RAM and an input/output interface. It is arranged to process the signals according to programs stored in the ROM while utilizing a temporary data storage function of the ROM, to implement hybrid drive controls of the engine8and first and second electric motors M1and M2, and drive controls such as shifting controls of the automatic transmission portion20.

The electronic control unit80, connected to various sensors and switches as shown inFIG. 4, receives various signals such as a signal indicative of an engine coolant temperature TEMPW; a signal indicative of a shift position PSHselected with a shift lever52(shown inFIG. 7) and a signal indicative of the number of operations initiated on the “M” position; a signal indicative of the engine speed NErepresenting the rotational speed of the engine8; a signal indicative of a gear train preset value; a signal commanding an M mode (manual shift running mode); a signal indicative of an operated state of an air conditioner; a signal indicative of the rotational speed (hereinafter referred to as “output shaft rotation speed”) NOUTof the output shaft22; a signal indicative of a temperature TOIL of working oil of the automatic transmission portion20.

The electronic control unit80also receives a signal indicative of a side brake under operation; a signal indicative of a foot brake under operation; a signal indicative of a temperature of a catalyst; a signal indicative of an accelerator opening Acc representing an operating stroke of an accelerator pedal when manipulated by a driver for his output demand value; a signal indicative of a cam angle; a signal indicative of a snow mode under setting; a signal indicative of a fore and aft acceleration value G of the vehicle; a signal indicative of an auto-cruising drive mode; a signal indicative of a weight vehicle weight) of the vehicle; a signal indicative of a wheel velocity of each drive wheel; a signal indicative of a rotational speed NM1of the first electric motor M1(hereinafter referred to as “first-electric motor speed NM1); a signal indicative of a rotational speed NM2of the second electric motor M2(hereinafter referred to as “second-electric motor speed NM2); and a signal indicative of a state of charge SOC stored in an electric-energy storage device60(seeFIG. 7).

The electronic control unit80generates various signals including: a control signal applied to an engine output control device58(seeFIG. 7) for controlling an engine output, i.e., a drive signal applied to a throttle actuator64for controlling a throttle valve opening θTHof an electronic throttle valve62disposed in an intake manifold60of the engine8; a fuel supply quantity signal applied to a fuel injecting device66for controlling an amount of fuel injected into the intake manifold60or cylinders of the engine8; an ignition signal applied to an ignition device68to control the ignition timing of the engine8; a supercharger pressure regulation signal for regulating a supercharger pressure of the engine8; an electric air-conditioner drive signal for actuating an electric air conditioner; command signals for commanding the operations of the first and second electric motors M1and M2; a shift-position (manipulated position) display signal for actuating a shift-range indicator; a gear-ratio indicating signal for displaying the gear ratio; a snow-mode display signal for displaying the presence of a snow-mode; and an ABS actuation signal for operating an ABS actuator to preclude slippages of the drive wheels during a braking phase.

The electronic control unit80also generates a M-mode display signal for displaying an M-mode being selected; valve command signals for actuating electromagnetic valves (linear solenoid valves), incorporated in the hydraulic control unit70(seeFIGS. 5 and 7) for controlling the hydraulic actuators of the hydraulically operated frictional coupling devices of the differential portion11and automatic transmission portion20; a signal for regulating a regulator valve (pressure regulator valve), incorporated in the hydraulic control unit70, to regulate a line pressure PL; a drive command signal for actuating an electric hydraulic pump acting as a hydraulic original-pressure source for the line pressure PLto be regulated; a signal for driving an electric heater; and a signal applied to a cruise-control computer.

As shown inFIG. 5, the hydraulic actuators AC1, AC2, AB1, AB2, AB3are connected to the respective linear solenoid valves SL1-SL5, which are controlled in response to control commands, delivered from the electronic control unit80. This adjusts the line pressure PL into respective clutch engaging pressures PC1, PC2, PB1, PB2and PB3to be applied directly to the respective hydraulic actuators AC1, AC2, AB1, AB2, AB3. The line pressure PLrepresents an original hydraulic pressure, generated by an electrically operated hydraulic oil pump (not shown) or a mechanical oil pump driven by the engine30, which is regulated by a relief-type pressure regulator valve depending on a load of the engine8in terms of an accelerator opening displacement or a throttle valve opening.

The linear solenoid valves SL1to SL5, fundamentally formed in the same structure, are independently energized or de-energized with the electronic control unit80. This allows the hydraulic actuators AC1, AC2, AB1, AB2, AB3to independently and controllably regulate hydraulic pressures, thereby controlling the clutch engaging pressures PC, PC2, PB1, PB2, PB3. With the automatic transmission portion20, predetermined coupling devices are coupled in a pattern indicated on, for instance, the coupling-operation indicating table shown inFIG. 2, thereby establishing various gear positions. In addition, during the shifting control of the automatic transmission portion20, a so-called clutch-to-clutch shifting is executed to simultaneously control the coupling or uncoupling of the clutches C and the brakes B relevant to the shifting operations.

FIG. 6is a view showing one example of a manually operated shifting device50serving as a changeover device operative to shift multiple kinds of shift positions PSHon manual operation. The shifting device50is mounted in, for instance, an area lateral to a driver's seat and includes a shift lever52to be manipulated for selecting one of the plurality of shift positions PSH.

The shift lever52has a parking position “P” (Parking) under which an inside of the transmission mechanism10, i.e., the power transmitting path inside the automatic transmission portion20is shut off in a neutral condition, i.e., a neutral state with the output shaft22of the automatic transmission portion20remained in a locked state; a reverse drive position “R” (Reverse) for a reverse drive mode; a neutral position “N” (Neutral) for the power transmitting path of the transmission mechanism10to be shut off in the neutral state; an automatic forward-drive running position “D” (Drive); and a manual-shift forward-drive position “M” (Manual).

In the automatic forward-drive running position “D”, an automatic shift mode is established for executing an automatic shift control within a varying range of a shiftable total speed ratio γT of the transmission mechanism10resulting from various gear positions whose automatic shift control is performed in a continuously variable speed ratio width of the differential portion11and a range of the 1st-speed to the 4th-speed gear positions of the automatic transmission portion20. The manual-shift forward-drive position “M” is manually shifted to establish a manual-shift forward-drive mode (manual mode) for setting a so-called shift range to limit a shifting gear position on a high speed range during the operation of the automatic transmission portion20under the automatic shift control.

As the shift lever52is shifted to the various shift positions PSH, the hydraulic control circuit70is electrically switched, thereby obtaining the reverse-drive “R” gear position, the neutral position “N” and the various gear shift positions or the like in the forward-drive gear position “D”.

Among the various shift positions PSHrepresented in the “P” to “M” positions, the “P” and “N” positions represent non-running positions selected when no vehicle is caused to run. That is, the “P” and “N” positions represent non-drive positions selected when the first and second clutches C1, C2select to cause the power transmitting path to be switched to a power cut-off state like a situation where as indicated in, for instance, the coupling operation indicating table shown inFIG. 2, both the first and second clutches C1, C2are uncoupled o interrupt the power transmitting path inside the automatic transmission portion20so as to disenable the driving of the vehicle.

The “R”, “D” and “M” positions represent running positions selected when the vehicle is caused to run. That is, these positions represent drive positions selected when the first and/or second clutches C1, C2select to cause the power transmitting path to be switched to a power transmitting state like a situation where as indicated in, for instance, the coupling operation indicating table shown inFIG. 2, at least one of the first and second clutches C1, C2is coupled to establish the power transmitting path inside the automatic transmission portion20so as to enable the vehicle to be driven.

More particularly, as the shift lever52is manually shifted from the “P” position or the “N” position to the “R” position, the second clutch C2is coupled to cause the power transmitting path of the automatic transmission portion20to be switched from the power cut-off state to the power transmitting state. With the shift lever52manually shifted from the “N” position to the “D” position, at least the first clutch C1is coupled to switch the power transmitting path of the automatic transmission portion20from the power cut-off state to the power transmitting state. With operation of the shift lever52to the “R” position, the second and third clutches C2and C3are engaged to establish the rearward running step.

Further, as the shift lever52is manually shifted from the “R” position to the “P” or “N” position, the second clutch C2is uncoupled to switch the power transmitting path of the automatic transmission portion20from the power transmitting state to the power cut-off state. With the shift lever52manually shifted from the “D” position to the “N” position, the first clutch C1or second clutch C2is uncoupled to switch the power transmitting path of the automatic transmission portion20from the power transmitting state to the power cut-off state.

FIG. 7is a functional block diagram illustrating major control functions to be executed by the electronic control unit80. Step-variable shifting control means82determines whether to execute the shifting of the automatic transmission portion20, i.e., the gear position to be shifted for causing the automatic transmission portion to execute the automatic shift control, based on the vehicle condition, represented by an actual vehicle speed V and the output torque TOUTby referring to the relationships (shifting lines and shifting map) involving upshift lines (in solid lines) and downshift lines (in single dot lines) shown inFIG. 8that are preliminarily stored as parameters of the vehicle speed V and the demanded output torque TOUT.

Upon determination of the gear position i.e. shift position to be shifted withFIG. 8, the step-variable shifting control means82outputs commands (a shift output command and a hydraulic pressure command) to the hydraulic control circuit70for coupling and/or uncoupling the hydraulically operated frictional coupling devices, involved in the shifting of the automatic transmission portion20so as to establish the gear position in accordance with the coupling table shown inFIG. 2. That is, the step-variable shifting control means82outputs a command to the hydraulic control circuit70for uncoupling the on-uncoupling side coupling device, involved, while coupling the on-coupling side coupling device in the shifting to cause the clutch-to-clutch shifting to be executed. Upon receipt of such commands, the hydraulic control circuit70causes the linear solenoid valves SL of the automatic transmission portion20to be actuated. This allows the hydraulically operated actuators of the hydraulically operated frictional coupling devices, involved in the relevant shifting, to be actuated. Thus, for instance, the on-uncoupling side coupling device is uncoupled and the on-coupling side coupling device is coupled, causing the automatic transmission portion20to execute the shifting.

The step-variable shift controlling means82operates in a manner described below with the shift lever52shifted in a manual shift mode to be placed in an “M” position representing a forward-drive manual shift running position. That is, the step-variable shift controlling means82operates, in response to the operation of the shift lever52placed in a “+” position or a “−” position, to set a high-speed-side gear position to any one of sequentially limited automatic shifting ranges to establish an engine braking condition. In an alternative, the step-variable shift controlling means82allows one of a plurality of gear positions to be directly determined to establish the engine braking condition. Such an engine braking condition, placed under the manual shift mode, is not mechanically effectuated in the present embodiment, but electrically realized with hybrid control means84, described later, in the same manner as that effectuated in the coast running mode.

Hybrid control means84operates the engine8in an optimum operating range at a high efficiency while distributing the drive forces of the engine8and the second electric motor M2at optimum rates and optimally varying a reacting force of the first electric motor M1during the operation thereof to generate electric power, thereby controllably operating the differential portion11under an electrically controlled continuously variable transmission to control a speed ratio γ0. At a vehicle speed V during the running of the vehicle in one occasion, for instance, a target (demanded) output for the vehicle is calculated based on the accelerator opening Acc and the vehicle speed V both of which represent output demanded variables of the driver, after which a demanded total target output is calculated based on the target output of the vehicle and a battery charge demanded value.

Subsequently, a target engine output is calculated in consideration of a loss in power transmission, loads of auxiliary units, assist torque of the second electric motor M2or the like so as to obtain the total target output. Then, the hybrid control means84controls the engine8, while controlling a rate of electric power being generated by the first electric motor M1, so as to obtain the engine speed NEand engine torque TEsuch that the target engine output is obtained.

The hybrid control means84executes such controls in consideration of, for instance, the gear position of the automatic transmission portion20with a view to increasing a dynamic performance and improving fuel consumption. During such hybrid controls, the differential portion11is caused to operate as the electrically controlled continuously variable transmission such that the engine speed NEand the vehicle speed V, determined for the engine8to operate in the operating range at a high efficiency, match the vehicle speed and the rotational speed of the power transmitting member18determined with the gear position in the automatic transmission portion20.

That is, the hybrid control means84determines a target value of the total speed ratio γT of the transmission mechanism10such that the engine8is caused to operate along an optimal fuel efficiency curve (a fuel efficiency map and the relationships) of the engine8as indicated by a dotted line inFIG. 9which is preliminarily and experimentally obtained and prestored. This achieves a compromise between driveability and fuel consumption during the running of the vehicle under a continuously variable shifting mode on a two-dimensional coordinate established with the engine speed NEand output torque (engine torque) TEof the engine8. For instance, the target value of the total speed ratio γT of the transmission mechanism10is determined so as to obtain engine torque TEand the engine speed NEfor generating the engine output demanded for satisfying target outputs (a total target output and demanded drive torque). Then, the speed ratio γ0of the differential portion11is controlled in consideration of the gear position in the automatic transmission portion20so as to obtain the relevant target value, thereby controlling the total speed ratio γT within a continuously variable shifting range.

When this takes place, the hybrid control means84allows electric energy, generated by the first electric motor M1, to be supplied through an inverter54to a battery device56and the second electric motor M2. Thus, a major part of drive power of the engine8is mechanically transferred to the power transmitting member18. However, a part of drive power of the engine8is consumed with the first electric motor M1for the generation of electric power and converted into electric energy. Resulting electric energy is supplied through the inverter54into the second electric motor M2, which is consequently driven. Therefore, the part of drive power is transferred through the second electric motor M2to the power transmitting member18. Equipment, involved in the operations starting from the step of generating electric power to the step of causing the second electric motor M2to consume resultant electric energy, establishes an electric path in which the part of the drive power of the engine8is converted into electric energy and resultant electric energy is converted into mechanical energy.

The hybrid control means84allows the differential portion11to perform an electrically controlled CVT function for controlling, for instance, a first-electric-motor rotational speed NM1and/or a second-electric-motor rotational speed NM2to maintain the engine speed NEat a nearly constant level or to control the rotational speed at an arbitrary level, regardless of the vehicle remaining under a halted condition or a running condition. In other words, the hybrid control means84controls the first-electric-motor rotational speed NM1and/or a second-electric-motor rotational speed NM2at an arbitrary level while maintaining the engine speed NEat the nearly constant level or the arbitrary rotational speed.

As will be apparent from the collinear chart shown inFIG. 3, for instance, when raising the engine speed NEduring the running of the vehicle, the hybrid control means84raises the first-electric-motor rotational speed NM1while maintaining a second-electric-motor rotational speed NM2at a nearly fixed level that is bound with the vehicle speed V (represented by the drive wheels34). In addition, when maintaining the engine speed NEat the nearly fixed level during the shifting of the automatic transmission portion20, the hybrid control means84varies the first-electric-motor rotational speed NM1in a direction opposite to that in which the second-electric-motor rotational speed NM2varies with the shifting of the automatic transmission portion20while maintaining the engine speed NEat the nearly fixed level.

The hybrid control means84causes the throttle actuator64to controllably open or close the electronic throttle valve62for performing a throttle control. In addition, the hybrid control means84functionally includes engine output control means that outputs commands to an engine output control device58singly or in combination. This causes a fuel injection device66to control a fuel injection quantity and a fuel injection timing for fuel injection control while causing an ignition device68to control an ignition timing of an ignition device68such as an igniter or the like for an ignition timing control. Upon receipt of such commands, the engine output control device58executes an output control of the engine8so as to provide a demanded engine output.

For instance, the hybrid control means84basically drives the throttle actuator60in response to the accelerator opening Acc by referring to the prestored relationship (not shown) The throttle control is execited such that the greater the accelerator opening Acc, the larger will be the throttle valve opening θTH. Upon receipt of the commands from the hybrid control means84, further, the engine output control device58allows the throttle actuator64to controllably open or close the electronic throttle valve62for throttle control while controlling the ignition timing of the ignition device68such as the igniter or the like for ignition timing control, thereby executing an engine torque control.

Further, the hybrid control means84allows the differential portion11to perform an electrically controlled CVT (differential action) to establish the motor-drive mode regardless of a halt or idling state of the engine8. For instance, the hybrid control means84executes the motor-drive mode under a relatively low output torque TOUTregion, i.e., a low engine torque region wherein engine efficiency is generally regarded to be lower than that of a high-torque region, or a relatively low vehicle-speed region of the vehicle speed V, i.e., a low load region.

Further, for the purpose of suppressing a drag of the halted engine8to provide improved fuel consumption during the motor-drive mode, the hybrid control means84controls a first-motor rotation speed NM1in a negative rotation speed to place the first electric motor M1under an unloaded condition for idling operation. This allows the differential portion11to perform the electrically controlled CVT (differential action), thereby maintaining the engine rotation speed NEat a zeroed or nearly zeroed level depending on needs.

Even if the engine-drive running region is present, the hybrid control means84allows the first electric motor M1and/or the battery device56to supply electric energy to the second electric motor M2using the electrical path mentioned above. This drives the second electric motor M2to apply torque to the drive wheels34, making it possible to provide a so-called torque-assist for assisting drive power of the engine8.

The hybrid control means84renders the first electric motor M1operative under the unloaded condition to freely rotate in the idling state. This makes it possible to cause the differential portion11to interrupt a torque transfer; i.e., the differential portion11is rendered inoperative with no output being provided under the same state as that in which the power transmitting path is disconnected in the differential portion11. That is, the hybrid control means84places the first electric motor M1in the unloaded condition, making it possible to place the differential portion11in a neutral condition (neutral state) in which the power transmitting path is electrically disconnected.

Further, the hybrid control means84has a function to serve as regeneration controlling means for charging electric energy to the battery56with a view to improving fuel consumption during a free-wheeling running state (coast running state) with an accelerator pedal being released, and a braking state with a foot brake being depressed in operation. That is, kinetic energy of the vehicle, i.e., a reversed drive force delivered from the drive wheels38to the engine8drivably rotates the second electric motor M2that serves as an electric power generator for generating such electric energy. Such electric energy, i.e., a second-motor power-generation current is charged to the battery56via the inverter54. This regenerative control is executed to achieve the amount of regeneration determined based on the charged sate (SOC) and the brake force distribution rate of the brake force resulting from the hydraulic brake for obtaining the brake force depending on the displacement of the accelerator pedal under depression.

Furthermore, when manual downshift determining means86determines during a non-accelerating running condition like the coast running state or the braking condition a request on a manual downshift, the hybrid control means84controls the first and second electric motors M1and M2in a manner as described below. That is, if the determination is made in response to the operation of the shift lever52being placed in the “−” position representing the presence of the request on the manual downshift by referring to the current range to another range lower by one gear position, the hybrid control means84controls the first and second electric motors M1and M2so as to generate a deceleration in line with the downshift.

FIG. 9is a collinear chart for illustrating how the differential portion11operates when the shift range is manually selected. For instance, if the shift lever52is manually shifted from a range “6” to a range “5”, the step-variable shift controlling means82initiates a downshift from a 4th-speed gear position to a 3rd-speed gear position while simultaneously controlling the rotation of the first electric motor M1so as to maintain the relationship plotted on a line of the range “6” shown inFIG. 9. This results in an increase in the engine rotation speed NE, thereby generating the deceleration (with an engine-brake force) corresponding to the “5” range.

If the shift lever52is manually shifted from the range “5” to the range “4”, the step-variable shift controlling means82allows the 3rd-speed gear position to be sustained while simultaneously raising the rotation speed of the first electric motor M1so as to maintain the relationship plotted on a line of the range “4” shown inFIG. 9. This results in an increase in the engine rotation speed NE. That is, this causes the differential portion11to increase the speed ratio γ0. This raises the engine rotation speed NE, thereby generating the deceleration (with an engine-braking force) corresponding to the range “4”.

Even if the shift lever52is manually shifted from the range “4” to the range “3”, from the range “3” to the range “2” and from the range “2” to the range “1”, the step-variable shift controlling means82similarly performs respective operations, thereby obtaining decelerations depending on a range that is manually selected. Such a control represents a normal control initiated for the request on the manual downshift, and the hybrid control means84functions as manual-downshift-request deceleration control means.

Limited shift determining means88determines based on a failure (breakdown or defect) occurring in the linear solenoid valve incorporated in the hydraulic control circuit70, whether or not the automatic shifting portion20intended to realize the deceleration required by the driver remains in a state disabling the change in the gear position. In addition, limited charge determining means90determines the operation based on whether or not the charged sate SOC reaches a predetermined upper limit, whether or not the battery56is available to be charged.

If the determination is made that the change in the gear position remains in the disabled state and a downshift is initiated for the gear position of the automatic shifting portion20for realizing the deceleration required by the driver, engine excessive rotation i.e. overspeed-rotation determining means92operates in a manner as described below. That is, the engine overspeed-rotation determining means92determines based on the current engine rotation speed NEwhether or not the engine8encounters an overspeed rotation state exceeding a predetermined upper limit level such as, for instance, 6000 rpm, in the presence of an attempt to increase the engine rotation speed NEby raising the rotation speed of the first electric motor M1based on the downshift.

If the manual downshift determining means86determines during a non-accelerating running state with the accelerator-opening Acc or the throttle opening θTHbeing zeroed a request on the manual downshift, on-limited-shift deceleration controlling means94operates in a manner described below. That is, upon request on the manual downshift, the limited shift determining means88determines that the automatic shifting portion20remains in the state disabling the change in the gear position. However, if the limited charge determining means90determines that the battery56still remains in a charge enabling state, the on-limited-shift deceleration controlling means94operates to realize the deceleration required by the driver.

More particularly, in order to realize a given rate of deceleration, the second electric motor M2is caused to perform the regeneration in place of initiating the downshift in the gear position of the automatic shifting portion20. Simultaneously, increasing the rotation speed of the first electric motor M1causes the engine rotation speed NEto increase, thereby generating the deceleration at a rate corresponding to the range manually selected by the driver.

In contrast, if the limited charge determining means90determines that the battery56still remains in a charge disabling state, then, the on-limited-shift deceleration controlling means94solely operates to increase the rotation speed of the first electric motor M1to a higher level than that achieved when the battery remains in the charge enabling state, causing a further increase in the engine rotation speed NE. This ensures the deceleration to be generated in line with the range manually selected by the driver.

Further, if the engine overspeed-rotation determining means92determines that the engine8will enter the overspeed rotation state, then, the on-limited-shift deceleration controlling means94solely operates to cause the second electric motor M2to perform the regeneration at a greater rate than that achieved when the engine rotation speed is available to increase. This ensures the deceleration to be generated at a rate corresponding to the range manually selected by the driver. That is, when the automatic shifting portion20remains in the state disabling the change in gear position, the rotation speed of the first electric motor M1is raised to alter the differential state of the electrically controlled differential portion11, thereby obtaining a variation in drive force at a rate corresponding to the operation of the shift lever52manually shifted by the driver.

FIG. 10is a flowchart for illustrating a basic sequence of control operations to be executed by the electronic control unit80. It illustrates a basic sequence of on-limited-shift deceleration controlling operations to be executed during the non-accelerating running state with the accelerator-opening Acc or the throttle opening θTHbeing zeroed. This sequence is repeatedly executed on an extremely short cycle time of, for instance, several milliseconds or several tens milliseconds.

First, step (hereinafter the term “step” is omitted) S1corresponding to the manual downshift determining means86determines presence/absence of a request on a manual downshift from the current range to another range lower by one gear position during the coast running (free-wheeling running) state with the accelerator pedal being released. This determination is made based on a fact that the shift lever52is shifted to the “−” position. If a negative determination is made in S1, then, the current routine is terminated.

If a positive determination is made in S1, then, S2corresponding to the limited shift determining means88determines whether or not the automatic shifting portion20remains in the state disabling the change in the gear position for realizing the deceleration required by the driver. This determination is made based on the occurrence of the failure (breakdown or defect) caused in the linear solenoid valve SL incorporated in the hydraulic control circuit70. If the determination is made positive in S2, then, S3corresponding to on-manual-downshift-request deceleration controlling means (hybrid control means84) executes a normal on-manual-downshift-request deceleration control. More particularly, the control is performed so as to switch the gear position of the step-variable shifting portion22while increasing the rotation speed of the first electric motor M1for obtaining the deceleration at a rate corresponding to the range manually selected by the driver.

If the determination is made negative in S2, then, S4corresponding to the limited charge determining means90determines based on the charged sate SOC whether or not the battery still remains in the charge enabling state. That is, it determines whether or not the second electric motor M2is available to generate electric power. If the determination is made positive in S4, then, SA5corresponding to the on-limited-shift deceleration controlling means94solely raises the rotation speed of the first electric motor M1to a level higher than that in which the charging is available, thereby providing a further increase in engine rotation speed NEso as to realize the deceleration required by the driver. This ensures the deceleration to be generated at a rate corresponding to the range manually selected by the driver.

However, if the determination is made negative in S4, then, S6corresponding to the engine overspeed-rotation determining means92determines whether or not the engine8will enter the overspeed rotating state. This is determined in the presence of an attempt to increase the engine rotation speed NEby raising the rotation speed of the first electric motor M1, in place of initiating the downshift for the gear position in the automatic shifting portion20. If the determination is made positive in S6, then, S7corresponding to the on-limited-shift deceleration controlling means94solely realizes the deceleration required by the driver. To this end, the second electric motor M2is caused to perform the regeneration at a greater rate than that achieved when the engine rotation speed is available to increase. This ensures the deceleration to be generated at the rate corresponding to the range manually selected by the driver.

However, if the determination is made negative in S6, then, S8corresponding to the on-limited-shift deceleration controlling means94causes the second electric motor M2to perform the regeneration, in place of initiating the downshift for the gear position in the automatic shifting portion20, with a view to realizing the deceleration required by the driver. Simultaneously, the first electric motor M1increases in rotation speed with an increase in engine rotation speed NE, thereby generating the deceleration at the rate corresponding to the range manually selected by the driver.

That is, when the automatic shifting portion20remains in the state disabling the change in the gear position, the rotation speed of the first electric motor M1is raised, i.e., the engine rotation speed NEincreases or the second electric motor M2performs the regeneration, thereby altering the differential state of the electrically controlled differential portion11. This makes it possible to obtain a variation in drive force depending on the manual shift operation of the shift lever52manipulated by the driver.

As set forth above, the electronic control device80of the shifting mechanism (vehicular power transmitting apparatus)10of the present embodiment, controls the differential state of the electrically controlled differential portion11, if the driver performs the manual shift operation using the shift lever52, i.e., when a shifting command is applied to the automatic shifting portion20remaining under the limited shifting state. This allows a variation to occur in the drive force in response to the shifting command, thereby appropriately preventing the occurrence of degradation in operability of the vehicle.

Further, the electronic control device80of the shifting mechanism10of the present embodiment issues the shifting command in response to the manual shift operation of the shift lever52effectuated by the driver. This allows a variation to occur in the drive force in synchronism with the shift operation of the driver, thereby appropriately preventing the occurrence of degradation in operability of the vehicle.

Still further, the electronic control device80of the shifting mechanism10of the present embodiment controls the differential state of the electrically controlled differential portion11upon changing the number of rotations of the engine (internal combustion engine)8. Thus, changing the number of rotations of the engine8results in a variation in drive force in response to the shifting command.

Moreover, the electronic control device80of the shifting mechanism10of the present embodiment controls the differential state of the electrically controlled differential portion11upon changing the power generating state of the second electric motor M2. Thus, changing the rotating state of the first electric motor M1or the power generating state of the second electric motor M2result in a variation in drive force in response to the shifting command.

In addition, the electronic control device80of the shifting mechanism10of the present embodiment controls the differential state of the differential portion11by altering the rotation speed NEof the engine8and altering the power generating state or the rotating state of the second electric motor M2depending on the charged sate of the battery56. Therefore, selectively varying the rotation speed NEof the engine8and varying the power generating state of the second electric motor M2result in the occurrence of a variation in drive force in response to the shifting command regardless of the charged sate of the battery56.

Further, the electronic control device80of the shifting mechanism10of the present embodiment controls the differential state of the electrically controlled differential portion11upon selectively altering the rotation speed NEof the engine8and altering the power generating state of the first electric motor M1or the second electric motor M2, depending on the state of the engine8. Therefore, selectively altering the rotation speed NEof the engine8or altering the power generating state of the second electric motor M2result in the occurrence of a variation in drive force in response to the shifting command, regardless of the power generating state of the second electric motor M2.

With the shifting mechanism10of the present embodiment, the automatic shifting portion20includes a mechanical type transmission that varies a speed ratio with varying a power transmitting point of torque. Therefore, rendering the electrically controlled differential portion11to operate as a continuously variable transmission by the electronic control device80, allows a whole of the shifting mechanism (vehicular power transmitting apparatus)10to have a drive force that continuously varies with infinitely varying the speed ratio.

The electronic control device80of the shifting mechanism10of the present embodiment renders the electrically controlled differential portion11operative to serve as the continuously variable transmission with controlling the operating state of the first electric motor M1or the second electric motor M2. Thus, drive torque is smoothly varied. In addition, the electrically controlled differential portion11can have not only a function to operate as an electrically controlled continuously variable transmission but also a function to operate as a step-variable transmission with varying the speed ratio step-by-step.

In the foregoing, the present invention, having been described with reference to the various embodiments shown in the drawings, may be implemented in various other modification or alternatives. For instance, although the previous embodiment has been described above with reference to the downshift being initiated through the manual operation, the present invention may be applied to an embodiment in which an upshift is initiated through a manual operation. Even in such embodiment, the vehicle can have a varying drive force even if the automatic shifting portion20executes the shifting in a limited state.

Instead for the second electric motor M2directly connected to the transmitting member18in the illustrated embodiments, the second electric motor M2may be connected to the power transmitting path extended from the engine8or the transmitting member18to the drive wheel38, directly or indirectly via the transmission, or the like.

In the illustrated embodiment set forth above, while the differential portion11(power distributing mechanism16) is configured to function as the electrically controlled continuously variable transmission in which the speed ratio γ0is continuously varied from the minimal value γ0minthe maximal value γ0maxthe present invention may be applied even to a case wherein the speed ratio γ0of the differential portion11is not continuously varied but pretended to vary step-by-step with the use of a differential action.

With the power distribution mechanisms16of the illustrated embodiments, the first carrier CA1is connected to the engine8; the first sun gear S1is connected to the first electric motor M1; and the first ring gear R1is connected to the power transmitting member18. However, the present invention is not necessarily limited to such connecting arrangement, and the engine8, first electric motor M1and power transmitting member18have no objection to be connected to either one of the three elements CA1, S1and R1of the first planetary gear set24.

Although the illustrated embodiment has been described with reference to the engine8directly connected to the input shaft14, these component parts may suffice to be operatively connected via, for instance, gears, belts or the like. No need may arise for the engine8and the input shaft14to be necessarily disposed on a common axis. The engine8may be, in addition to the internal combustion engine, an external combustion engine or other type drive force generating mechanism.

Further, while the illustrated embodiment has been described with reference to the first electric motor M1and the second electric motor M2wherein the first electric motor M1is coaxially disposed with the drive apparatus input shaft14and connected to the first sun gear S1upon which the second electric motor M2is connected to the power transmitting member18. However, no need arises for these component parts to be necessarily placed in such connecting arrangement. For example, the first electric motor M1may be connected to the first sun gear S1through gears, a belt or the like, and the second electric motor M2may be connected to the power transmitting member18.

Instead for the automatic shifting portion20comprised of the planetary gear type step variable transmission in the illustrated embodiments, the automatic shifting portion20may be a constantly engaged parallel shaft type transmission, a belt type continuously variable transmission, or the like. In summary, any mechanical transmission of which shifting ratio changes as change of the torque transmitting path.

In the illustrated embodiment, further, the hydraulically operated frictional coupling devices such as the first and second clutches C1, C2may include magnetic type clutches such as powder (magnetic powder) clutches, electromagnetic clutches and meshing type dog clutches, and electromagnetic type and mechanical coupling devices. For instance, with the electromagnetic clutches being employed, the hydraulic control circuit70may not include a valve device for switching hydraulic passages and may be replaced with a switching device or electromagnetically operated switching device or the like that are operative to switch electrical command signal circuits for electromagnetic clutches.

While the illustrated embodiment has been described above with reference to the automatic transmission portion20that is connected to the differential portion11in series via the power transmitting member18, a countershaft may be provided in parallel to the input shaft14to allow the automatic transmission portion20to be coaxially disposed on an axis of the countershaft. In this case, the differential portion11and the automatic transmission portion20may be connected to each other in power transmitting capability via a set of transmitting members structured of, for instance, a counter-gear pair acting as the power transmitting member18, a sprocket and a chain.

Further, the power distributing mechanism16of the illustrated embodiment may include, for instance, a differential gear set in which a pinion, rotatably driven with the engine, and a pair of bevel gears, held in meshing engagement with the pinion, are operatively connected to the first electric motor M1and the power transmitting member18(second electric motor M2).

The power distributing mechanism16of the illustrated embodiment has been described above as including one set of planetary gear units, the power distributing mechanism16may include two or more sets of planetary gear units that are arranged to function as a transmission having three or more speed positions under a non-differential state (fixed shifting state). In addition, the planetary gear unit is not limited to the single-pinion type, but may be of a double-pinion type.

While the shift operating device50of the illustrated embodiment has been described with reference to the shift lever52operative to select a plurality of kinds of shift positions PSH, the shift lever52may be replaced by other type of switches or devices. These may include, for instance: a select switch such as a press-button type switch and a slide-type switch available to select one of a plurality of shift positions PSH; a device operative to switch a plurality of shift positions PSHin response not to the manipulation initiated by the hand but to a driver's voice; and a device operative to switch a plurality of shift positions PSHin response to the manipulation initiated by the foot.

While the illustrated embodiment has been described with reference to the shifting range that is established upon manipulating the shift lever52to the “M” position, the gear positions may be set, i.e., maximal speed gear positions for respective shifting ranges may be set as the gear positions. In this case, the automatic transmission portion20operates so as to allow the gear positions to be switched for executing the shifting action. For example, as the shift lever.52is manually operated to an up-shift position “+” or a down-shift position “−” in the “M” position, the automatic transmission portion20operates so as to allow any of the 1st-speed gear position to the 4th-speed gear position to be set depending on the manipulation of the shift lever52.

The foregoing merely illustrates the embodiments for illustrating the principles of the present invention. It will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in the light of the overall teachings of the disclosure.