Patent Application
20200269831
This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2019-033581 filed on Feb. 27, 2019, the content of which is incorporated herein by reference.
This invention relates to a drive apparatus of a hybrid vehicle.
Conventionally, there is a known apparatus of this type that includes an engine, a first electric motor (first motor-generator), a second electric motor (second motor-generator), a power splitting planetary gear mechanism able to split power generated by the engine between output side and first electric motor side, a speed ratio changing planetary gear mechanism for changing speed ratio of rotation output from the output side, and multiple frictional engagement mechanisms. Such an apparatus is described, for example, in Japanese Patent Publication No. 5391959 (JP5391959B). In the apparatus described in JP5391959B, a configuration is adopted that controls engaging action of the multiple frictional engagement mechanisms to enable implementation of an EV mode for traveling by power of the second electric motor with the engine stopped, a series mode for traveling by power of the second electric motor while the first electric motor is driven to generate electricity by power of the engine, and a HV mode for traveling by power of the engine and power of the second motor.
However, the apparatus to according JP5391959B has an issue regarding a reverse travel in EV mode in cases requiring large driving force such as when riding over a step or the like. This is because maximum driving force of the apparatus according to JP5391959B during the reverse travel in EV mode is dictated by capacity of the second electric motor, so that increasing driving force requires use of a larger second motor and therefore leads to increased cost and larger overall apparatus size.
An aspect of the present invention is a drive apparatus of a hybrid vehicle including: an internal combustion engine; a first motor-generator; a drive shaft connected to a wheel; a power division mechanism connected to an output shaft of the internal combustion engine to divide and output a power generated by the internal combustion engine to the first motor-generator and a power transmission path configured to connect the power division mechanism and the drive shaft; a second motor-generator disposed in the power transmission path; a planetary gear mechanism interposed between the second motor-generator and the power division mechanism in the power transmission path; a speed change mechanism including a first engagement mechanism configured to be engageable and disengageable and a second engagement mechanism configured to be engageable and disengageable so as to change a speed ratio defined as a value of a ratio of a rotational speed of an input shaft of the planetary gear mechanism relative to a rotational speed of an output shaft of the planetary gear mechanism, in accordance with an engagement action of the first engagement mechanism and the second engagement mechanism; and an electronic control unit including a microprocessor configured to perform controlling the internal combustion engine, the first motor-generator, the second motor-generator and the speed change mechanism in accordance with a drive mode. The speed change mechanism is configured so that the speed ratio is a first speed ratio when the first engagement mechanism is disengaged and the second engagement mechanism is engaged and the speed ratio is a second speed ratio less than the first speed ratio when the first engagement mechanism is engaged and the second engagement mechanism is disengaged. The drive mode includes an EV reverse mode driven by a power of the second motor-generator with the internal combustion engine inactivated to travel in reverse. The microprocessor is configured to further perform determining whether a driving force increase instruction is output during traveling in the EV reverse mode, and the microprocessor is configured to perform the controlling including controlling the speed change mechanism so as to disengage the first engagement mechanism and engage the second engagement mechanism before the driving force increase instruction is output during traveling in the EV reverse mode and so as to engage the first engagement mechanism and disengage the second engagement mechanism when it is determined that the driving force increase instruction is output during traveling in the EV reverse mode.
The objects, features, and advantages of the present invention will become clearer from the following description of embodiments in relation to the attached drawings, in which:
Hereinafter, an embodiment of the present invention is explained with reference to
As shown in
The engine 1 is an internal combustion engine (e.g., gasoline engine) wherein intake air supplied through a throttle valve and fuel injected from an injector are mixed at an appropriate ratio and thereafter ignited by a sparkplug or the like to burn explosively and thereby generate rotational power. A diesel engine or any of various other types of engine can be used instead of a gasoline engine. Throttle valve opening, quantity of fuel injected from the injector (injection time and injection time period) and ignition time are, inter alia, controlled by a controller (ECU) 4.
An output shaft 1a of the engine 1 extends centered on axis (axial line) CL1. The engine 1 incorporates a one-way clutch 1b which allows rotation (normal rotation) of the output shaft 1a in positive direction and prevents rotation (reverse rotation) of the output shaft 1a in negative direction. The engine 1 can generate driving force for forward travel of the vehicle.
The first and second motor-generators 2 and 3 each has a substantially cylindrical rotor centered on axis CL1 and a substantially cylindrical stator installed around the rotor and can function as a motor and as a generator. Namely, the rotors of the first and second motor-generators 2 and 3 are driven by electric power supplied from a battery 6 through a power control unit (PCU) 5 to coils of the stators. In such case, the first and second motor-generators 2 and 3 function as motors.
On the other hand, when rotating shafts 2a and 3a of rotors of the first and second motor-generators 2 and 3 are driven by external forces, the first and second motor-generators 2 and 3 generate electric power that is applied through the power control unit 5 to charge the battery 6. In such case, the first and second motor-generators 2 and 3 function as generators. During normal vehicle traveling, such as during cruising or acceleration, for example, the first motor-generator 2 functions chiefly as a generator and the second motor-generator 3 functions chiefly as a motor.
The power control unit 5 incorporates an inverter controlled by instructions from the controller 4 so as to individually control output torque or regenerative torque of the first motor-generator 2 and the second motor-generator 3. The first and second motor-generators 2 and 3 can rotate in positive direction and negative direction.
The first motor-generator 2 and the second motor-generator 3 are coaxially installed at spaced locations. The first motor-generator 2 and second motor-generator 3 are, for example, housed in a common case 7, and a space SP between them is enclosed by the case 7. Optionally, the first motor-generator 2 and second motor-generator 3 can be housed in separate cases.
The first planetary gear mechanism 10 and second planetary gear mechanism 20 of single pinion type are installed in the space SP between the first motor-generator 2 and second motor-generator 3. Specifically, the first planetary gear mechanism 10 is situated on the side of the first motor-generator 2 and the second planetary gear mechanism 20 on the side of the second motor-generator 3.
The first planetary gear mechanism 10 includes a first sun gear 11 and a first ring gear 12 installed around the first sun gear 11, both of which rotate around axis CL1, multiple circumferentially spaced first pinions (planetary gears) 13 installed between the first sun gear 11 and first ring gear 12 to mesh with these gears 11 and 12, and a first carrier 14 that supports the first pinions 13 to be individually rotatable around their own axes and collectively revolvable around axis CL1.
Similarly to the first planetary gear mechanism 10, the second planetary gear mechanism 20 includes a second sun gear 21 and a second ring gear 22 installed around the second sun gear 21, both of which rotate around axis CL1, multiple circumferentially spaced second pinions (planetary gears) 23 installed between the second sun gear 21 and second ring gear 22 to mesh with these gears 21 and 22, and a second carrier 24 that supports the second pinions 23 to be individually rotatable around their own axes and collectively revolvable around axis CL1.
The output shaft 1a of the engine 1 is connected to the first carrier 14, and power of the engine 1 is input to the first planetary gear mechanism 10 through the first carrier 14. On the other hand, when the engine 1 is started, power from the first motor-generator 2 is input to the engine 1 through the first planetary gear mechanism 10. The first sun gear 11 is connected to the rotating shaft 2a of the rotor of the first motor-generator 2, and the first sun gear 11 and first motor-generator 2 (rotor) rotate integrally. The first ring gear 12 is connected to the second carrier 24, and the first ring gear 12 and second carrier 24 rotate integrally.
Owing to this configuration, the first planetary gear mechanism 10 can output power received from the first carrier 14 through the first sun gear 11 to the first motor-generator 2 and output power through the first ring gear 12 to the second carrier 24 on an axle (drive shaft) 57 side. In other words, it can dividedly output power from the engine 1 to the first motor-generator 2 and the second planetary gear mechanism 20.
An axis CL1-centered substantially cylindrical outer drum 25 is provided radially outside the second ring gear 22. The second ring gear 22 is connected to and rotates integrally with the outer drum 25. A brake mechanism 30 is provided radially outward of the outer drum 25. The brake mechanism 30 is, for example, structured as a multi-plate wet brake including multiple radially extending plates (friction members) 31 arranged in axial direction and multiple radially extending disks (friction members) 32 arranged in axial direction (multiple illustration is omitted in the drawing). The plates 31 and disks 32 are alternately arranged in axial direction. In other words, the brake mechanism 30 includes plates 31 and disks 32 as a plurality of friction engagement elements.
The multiple plates 31 are circumferentially non-rotatably and axially movably engaged at their radial outer ends with the inner peripheral surface of the surrounding wall of the case 7. The multiple disks 32 rotate integrally with the outer drum 25 owing to their radially inner ends being engaged with outer peripheral surface of the outer drum 25 to be circumferentially non-rotatable and axially movable relative to the outer drum 25. A non-contact rotational speed sensor 35 for detecting rotational speed of the outer drum 25 is provided on inner peripheral surface of the case 7 to face outer peripheral surface of the outer drum 25 axially sideward of the brake mechanism 30.
The brake mechanism 30 includes a spring (not shown) for applying biasing force acting to separate the plates 31 and disks 32 and thus release the disks 32 from the plates 31, and a piston (not shown) for applying pushing force acting against the biasing force of the spring to engage the plates 31 and disks 32. The piston is driven by hydraulic pressure supplied through a hydraulic pressure control unit 8.
In a state with no hydraulic pressure acting on the piston, the plates 31 and disks 32 separate, thereby releasing (turning OFF) the brake mechanism 30 and allowing rotation of the second ring gear 22. On the other hand, when hydraulic pressure acts on the piston, the plates 31 and disks 32 engage, thereby operating (turning ON) the brake mechanism 30. In this state, rotation of the second ring gear 22 is prevented. The configuration of the brake mechanism 30 is not limited to the above configuration. For example, the brake mechanism may be configured to generate braking force by pressing a friction member supported by the case 7 to an outer peripheral surface of the outer drum 25.
An axis CL1-centered substantially cylindrical inner drum 26 is provided radially inward of and facing the outer drum 25. The second sun gear 21 is connected to an output shaft 27 of a second planetary gear mechanism 20 that extends along axis CL1 and is connected to the inner drum 26, whereby the second sun gear 21, output shaft 27 and inner drum 26 rotate integrally. A clutch mechanism 40 is provided between the outer drum 25 and the inner drum 26.
The clutch mechanism 40 is, for example, structured as a multi-plate wet clutch including multiple radially extending plates (friction members) 41 arranged in axial direction and multiple radially extending disks (friction members) 42 arranged in axial direction (multiple illustration is omitted in the drawing). The plates 41 and disks 42 are alternately arranged in axial direction. In other words, the clutch mechanism 40 includes plates 41 and disks 42 as a plurality of friction engagement elements.
The multiple plates 41 rotate integrally with the outer drum 25 owing to their radial outer ends being engaged with the inner peripheral surface of the outer drum 25 to be circumferentially non-rotatable and axially movable relative to the outer drum 25. The multiple disks 42 rotate integrally with the inner drum 26 owing to their radially inner ends being engaged with outer peripheral surface of the inner drum 26 to be circumferentially non-rotatable and axially movable relative to the inner drum 26.
The clutch mechanism 40 includes a spring (not shown) for applying biasing force acting to separate the plates 41 and disks 42 and thus release the disks 42 from the plates 41, and a piston (not shown) for applying pushing force acting against the biasing force of the spring to engage the plates 41 and disks 42. The piston is driven by hydraulic pressure supplied through the hydraulic pressure control unit 8.
In a state with no hydraulic pressure acting on the piston, the plates 41 and disks 42 separate, thereby releasing (turning OFF) the clutch mechanism 40 and allowing relative rotation of the second sun gear 21 with respect to the second ring gear 22. When rotation of the second ring gear 22 is prevented by the brake mechanism 30 being ON at this time, rotation of the output shaft 27 with respect to the second carrier 24 is accelerated. This state corresponds to speed ratio stage being shifted to high.
On the other hand, when hydraulic pressure acts on the piston, the plates 41 and disks 42 engage, thereby operating (turning ON) the clutch mechanism 40 and integrally joining the second sun gear 21 and second ring gear 22. When rotation of the second ring gear 22 is allowed by the brake mechanism 30 being OFF at this time, the output shaft 27 becomes integral with the second carrier 24 and rotates at the same speed as the second carrier 24. This state corresponds to speed ratio stage being shifted to low.
The second planetary gear mechanism 20, brake mechanism 30 and clutch mechanism 40 configure a speed change mechanism 70 that shifts rotation of the second carrier 24 between two speed stages (high and low) and outputs the shifted rotation from the output shaft 27. A value of ratio of a rotational speed of an input shaft (second carrier 24) relative to a rotational speed of the output shaft 27 (second sun gear 21) of the second planetary gear mechanism 20 is defined as speed ratio. The speed ratio α1 (called first speed ratio) in low-speed range is greater than the speed ratio α2 (called second speed ratio) in high-speed range. Torque transmission path from the first planetary gear mechanism 10 to the rotating shaft 3a of the rotor of the second motor-generator 3 through the speed change mechanism 70 configures a first power transmission path 71 in a power transmission path 73 from the first planetary gear mechanism 10 to the axles 57.
The output shaft 27 is connected to an output gear 51 centered on axis CL1. The rotating shaft 3a of the rotor of the second motor-generator 3 is connected to the output gear 51 so that the second motor-generator 3 (rotating shaft 3a) and the output gear 51 integrally rotate. A large-diameter gear 53 rotatable around a counter shaft 52 lying parallel to axis CL1 meshes with the output gear 51, and torque is transmitted to the counter shaft 52 through the large-diameter gear 53. Torque transmitted to the counter shaft 52 is transmitted through a small-diameter gear 54 to a ring gear 56 of a differential unit 55 and further transmitted through the differential unit 55 to the left and right axles (drive shaft) 57. Since this drives the wheels (for example, front wheels) 101, the vehicle travels. The rotating shaft 3a, output gear 51, large-diameter gear 53, small-diameter gear 54 and differential unit 55, inter alia, configure a second power transmission path 72 from the second motor-generator 3 to the axles 57 in the power transmission path 73.
An oil pump (MOP) 60 is installed radially inward of the rotor of the second motor-generator 3. The oil pump 60 is connected to the output shaft 1a of the engine 1 and driven by the engine 1. Oil supply necessary when the engine 1 is stopped is covered by driving an electric oil pump (EOP) 61 with power from the battery 6.
The hydraulic pressure control unit 8 includes electromagnetic valve, proportional electromagnetic valve, and other control valves (control valve 8a) actuated in accordance with electric signals. The control valve 8a operates to control hydraulic pressure flow to the brake mechanism 30, clutch mechanism 40 and the like in accordance with instructions from the controller 4. More specifically, the control valve 8a controls hydraulic oil flow to an oil chamber facing piston of the brake mechanism 30 and to an oil chamber facing piston of the clutch mechanism 40. This enables ON-OFF switching of the brake mechanism 30 and clutch mechanism 40. Hydraulic oil flow to the other portion is controlled by other control valve.
The controller (ECU) 4 as an electronic control unit incorporates an arithmetic processing unit having a CPU, ROM, RAM and other peripheral circuits, and the CPU includes an engine control ECU 4a, a speed change mechanism control ECU 4b and a motor-generator control ECU 4c. Alternatively, the multiple ECUs 4a to 4c need not be incorporated in the single controller 4 but can instead be provided as multiple discrete controllers 4 corresponding to the ECUs 4a to 4c.
The controller 4 receives as input signals from, inter alia, the rotational speed sensor 35 for detecting rotational speed of the drum 25, a vehicle speed sensor 36 for detecting vehicle speed, and an accelerator opening angle sensor 37 for detecting accelerator opening angle indicative of amount of accelerator pedal depression. Although not indicated in the drawings, the controller 4 also receives signals from a sensor for detecting rotational speed of the engine 1, a sensor for detecting rotational speed of the first motor-generator 2 and a sensor for detecting rotational speed of the second motor-generator 3.
Based on these input signals, the controller 4 decides drive mode in accordance with a predefined driving force map representing vehicle driving force characteristics defined in terms of factors such as vehicle speed and accelerator opening angle. In order to enable the vehicle to travel in the decided drive mode, the controller 4 controls operation of the engine 1, first and second motor-generators 2 and 3, the brake mechanism 30 and the clutch mechanism 40 by outputting control signals to, inter alia, an actuator for regulating throttle valve opening, an injector for injecting fuel, the power control unit 5 and the hydraulic pressure control unit 8 (control valve 8a).
In
In EV mode, the vehicle is driven for traveling solely by motive power of the second motor-generator 3. In EV mode, the vehicle travels forward when the second motor-generator 3 is rotated along the plus direction, while the vehicle travels backward when the second motor-generator 3 is rotated along the negative direction. In EV mode, the brake mechanism 30 and clutch mechanism 40 are both OFF, and the engine 1 is stopped, in accordance with instructions from the controller 4.
In W motor mode, the vehicle is driven for traveling by motive power of the first motor-generator 2 and the second motor-generator 3. In W motor mode, the brake mechanism 30 is OFF, the clutch mechanism 40 is ON and the engine 1 is stopped, in accordance with instructions from the controller 4.
In series mode, the vehicle is driven for traveling by motive power of the second motor-generator 3 while the first motor-generator 2 is being driven by motive power from the engine 1 to generate electric power. In series mode, the brake mechanism 30 and clutch mechanism 40 are both ON and the engine 1 is operated, in accordance with instructions from the controller 4.
In HV mode, the vehicle is driven for traveling by motive power produced by the engine 1 and the second motor-generator 3. Within the HV mode, the HV low mode corresponds to a mode of wide-open acceleration from low speed, and the HV high mode corresponds to a mode of normal traveling after EV traveling. In HV low mode, the brake mechanism 30 is OFF, the clutch mechanism 40 is ON and the engine 1 is operated, in accordance with instructions from the controller 4. In HV high mode, the brake mechanism 30 is ON, the clutch mechanism 40 is OFF and the engine 1 is operated, in accordance with instructions from the controller 4.
In the so-configured drive apparatus 100, reverse travel is performed in EV mode (called “EV reverse mode”). Specifically, when reverse travel is instructed by operation of a shift lever, the engine 1 is stopped by an instruction from the controller 4 and the vehicle is propelled by driving force from the second motor-generator 3. If one or more of wheels 101 should then hit a step-like rise during reverse travel, considerable driving force will be needed to ride over the rise. If this driving force is to be covered solely by the second motor-generator 3, a large second motor-generator 3 capable of producing high maximum torque must be adopted. This leads to high equipment cost and large size of the drive apparatus 100.
Two methods are conceivable for increasing driving force in EV reverse mode without increasing maximum torque of the second motor-generator 3. The first method is to mechanically prevent normal rotation of the engine 1 and once this condition is established to add torque of the first motor-generator 2 to the second motor-generator 3.
In the first method, the one-way clutch 1b for preventing reverse rotation (negative direction rotation) of the output shaft 1a of the engine 1 is replaced by a two-way clutch. The two-way clutch is adapted to be switchable by an electromagnetic actuator between locked state and unlocked state. The electromagnetic actuator switches the two-way clutch to unlocked state during normal traveling when no increase in driving force is necessary. In unlocked state, normal rotation of the engine 1 is allowed and reverse rotation of the engine 1 is prevented. On the other hand, when a need to increase driving force arises during traveling in EV reverse mode, the electromagnetic actuator switches the two-way clutch to locked state in response to instruction from the controller 4. In locked state, both normal rotation and reverse rotation of the engine 1 are prevented.
At this time, as indicated in
Although not illustrated, the second method requires a planetary gear mechanism or other torque amplification mechanism to be added in the second power transmission path 72. Increase in number of components therefore also increases cost and weight of the apparatus as a whole in the second method. Against this backdrop, the drive apparatus 100 according to the present embodiment is therefore configured as set out in the following in order to enable driving force increase in EV reverse mode while minimizing increase in number of components.
A reverse driving force increase instruction is output by the controller 4. For example, during EV reverse traveling, when vehicle speed detected by the vehicle speed sensor 36 is equal to or lower than a predetermined value and accelerator opening angle detected by the accelerator opening angle sensor 37 is equal to or greater than a predetermined value, the controller 4 determines that temporary increase of reverse driving force is necessary and outputs a reverse driving force increase instruction. As an actual situation in which a reverse driving force increase instruction is output can be cited a case such as when, during rear wheel traveling, collision of a wheel or wheels with a step (e.g., a curb) decreases vehicle speed and the driver increases accelerator pedal depression in order to ride over the step.
As shown in
As shown in
In addition, the first motor-generator 2 is rotationally driven in positive direction in response to a command from the controller 4 synchronous with start of inertia phase, whereby rotational speed of the first motor-generator 2 rises to predetermined upper limit rotational speed Nmax and rotational speed of the first carrier 14 (engine 1) also concomitantly rises, as indicated in
It is during switching transition from low-speed range to high-speed range that the first motor-generator 2 is rotationally driven in positive direction. Therefore, when rotational speed of the outer drum 25 detected by the rotational speed sensor 35 reaches a predetermined rotational speed following upshift, or when rotational speed of the first motor-generator 2 reaches upper limit rotational speed Nmax, torque of the first motor-generator 2 is returned to substantially 0.
First, in S1 (S: processing Step) of the flowchart in
Next, in S4, whether temporary increase of reverse driving force is necessary is determined based on signals from the vehicle speed sensor 36 and the accelerator opening angle sensor 37. This determination is performed, for example, by storing in memory in advance a reverse driving force increase required region mapped with respect to vehicle speed and accelerator opening angle and using signals from the vehicle speed sensor 36 and accelerator opening angle sensor 37 to determine whether operating point on the map falls in the reverse driving force increase required region. For example, the map can be created such that operating point is in the reverse driving force increase required region when vehicle speed is 0 and accelerator opening angle is a predetermined value or greater. Alternatively, whether temporary increase of reverse driving force is necessary can be determined simply by determining whether vehicle speed is equal to or lower than predetermined value and accelerator opening angle is equal to or greater than predetermined value. When the result in S4 is YES, the program goes to S5, and when NO, returns to S1.
In S5, upshift of the speed change mechanism 70 is started. Namely, clutch regripping is performed by outputting control signals to the control valve 8a to gradually lower engaging force (clutch torque) of the clutch mechanism 40 and gradually increase engaging force (clutch torque) of the brake mechanism 30 at a programmed time point. Next, in S6, signals from the rotational speed sensor 35 are used to determine whether predetermined rotational fluctuation of the second ring gear 22 is detected, i.e., whether inertia phase is started. When the result in S6 is YES, the program goes to S7, and when NO, returns to S5.
In S7, a control signal is output to the power control unit 5 to increase torque of the first motor-generator 2 to a predetermined value. This adds torque of the first motor-generator 2 to the second motor-generator 3. Moreover, rotational speed of the first motor-generator 2 increases concomitantly with increase in torque of the first motor-generator 2. Next, in S8, whether rotational speed of the first motor-generator 2 reaches upper limit rotational speed Nmax is determined based on a signal from a sensor that detects rotational speed of the first motor-generator 2. Upper limit rotational speed Nmax is set to a value not exceeding design-allowable rotational speed of the second motor-generator 3. When the result in S8 is NO, the program goes to S9, and when YES, skips S9 and goes to S10.
In S9, whether upshift is complete is determined based on a signal from the rotational speed sensor 35. Completion of upshift is determined, for example, from whether rotational speed of the second ring gear 22 became 0. When the result in S9 is YES, the program goes to S10, and when NO, returns to S7. In S10, a control signal is output to the power control unit 5 to lower driving torque of the first motor-generator 2 to a value barely capable of maintaining rotation, i.e., to almost 0, whereafter processing is terminated.
As shown in
When a wheel or wheels hit a step (or step-like rise) at time t1, for example, reverse travel resistance force increases, and when an instruction for increase of reverse driving force for riding over the step is output, clutch torque of the clutch mechanism 40 is gradually lowered and upshift action is started (S5). Clutch torque of the brake mechanism 30 is thereafter gradually increased from 0, and when the rotational speed sensor 35 detects predetermined rotational fluctuation (e.g., rotational speed increase of at least predetermined value) of the second ring gear 22 at time t2, i.e., when transition to inertia phase begins, driving torque of the first motor-generator 2 increases to predetermined value T1 and rotational speed of the first motor-generator 2 increases (S7).
Since upshift of the speed change mechanism 70 is thus performed when a reverse driving force increase instruction is output, the output shaft 27 can be caused to generate high torque in inertia phase while in switching transition from low-speed range to high-speed range. Moreover, the first motor-generator 2 is caused to generate driving torque that is added to the second motor-generator 3. Therefore, reverse driving force rises from F1 to F2, and the wheel(s) can easily ride over the step.
Thereafter, when, for example, rotational speed of the first motor-generator 2 reaches upper limit rotational speed Nmax at time t3, torque of the first motor-generator 2 returns to substantially 0 (S8→S10). Reverse driving force therefore falls to its original value F1. Moreover, detection of upshift completion by the rotational speed sensor 35 (e.g., when rotational speed of the second ring gear 22 becomes 0) also means that driving torque of the first motor-generator 2 is substantially 0 (S9→S10). Although not illustrated in the drawing, in such case the speed change mechanism 70 is thereafter is switched from high-speed range back to low-speed range, and operations like the aforesaid are performed at every output of an instruction for reverse driving force increase.
The present embodiment can achieve advantages and effects such as the following:
(1) The hybrid vehicle drive apparatus 100 according to the present embodiment includes: the engine 1; the first motor-generator 2; the first planetary gear mechanism 10 connected to the output shaft 1a of the engine 1 to divide and output power generated by the engine 1 to the first motor-generator 2 and the power transmission path 73 for transmitting power to axles 57; the second motor-generator 3 installed in the power transmission path 73; the second planetary gear mechanism 20 installed in the first power transmission path 71 between the second motor-generator 3 and the first planetary gear mechanism 10; the speed change mechanism 70 including the engageable/disengageable brake mechanism 30 and clutch mechanism 40 so as to change speed ratio defined as value of ratio of rotational speed of input shaft of the second planetary gear mechanism (of second carrier 24) relative to rotational speed of the output shaft 27 of the second planetary gear mechanism 20 in accordance with engagement action; and the controller 4 for controlling the engine 1, the first motor-generator 2, the second motor-generator 3 and the speed change mechanism 70 in accordance with drive mode (
Thus, in EV reverse mode, switching of the speed change mechanism 70 from low-speed range to high-speed range enables generation of large torque at the output shaft 27 of the speed change mechanism 70 upon entering inertia phase while the switching is transitioning. As a result, reverse driving force can be temporarily increased so as to generate driving force of or greater than maximum torque inherent to the second motor-generator 3. This enables easy wheel ride-over of a step or similar. Moreover, as no size increase of the second motor-generator 3 is required, rise in cost and enlargement of the drive apparatus 100 can be minimized. In addition, although the brake mechanism 30 and the clutch mechanism 40 are both turned OFF during forward traveling in EV mode (
(2) When a driving force increase instruction is determined to be output during traveling in EV reverse mode, the controller 4 controls the first motor-generator 2 so that torque output from the first motor-generator 2 is added to the second motor-generator 3. Since torque of the first motor-generator 2 is therefore applied to further increase reverse driving force, reliable ride-over or the like of step-like rises can be achieved.
(3) The hybrid vehicle drive apparatus 100 further includes the one-way clutch 1b that allows rotation of the engine 1 in one direction (positive direction) and prevents rotation of the engine 1 in reverse direction (negative direction) (
Various modifications of the aforesaid embodiment are possible. Some examples are explained in the following. In the aforesaid embodiment, the first motor-generator 2 is controlled in EV reverse mode to output driving torque in positive direction upon detection of passage into inertia phase during switching transition from low-speed range to high-speed range. However, such output of driving torque can be omitted.
As shown in
In the aforesaid embodiment, the engine 1 is equipped with the one-way clutch 1b and minimum rotational speed of the engine 1 is mechanically limited to 0. However, the one-way clutch can be omitted. In such case, engine speed in EV reverse mode before a reverse driving force increase instruction is output can be set to a value smaller than 0.
Although in the aforesaid embodiment (
In the aforesaid embodiment (
In the aforesaid embodiment, the controller 4 as an electronic control unit is adapted to control actions of the brake mechanism 30 and clutch mechanism 40 so as to implement EV mode, W motor mode, series mode, HV mode (HV low mode, HV high mode), EV reverse mode and the like, but can also be adapted to implement other modes.
In the aforesaid embodiment, a start of an inertia phase during a transition state of changing speed ratio from a first speed ratio α1 to a second speed ratio α2 is detected based on signal from the rotational speed sensor 35. However, a detecting part is not limited to the aforesaid configuration. In the aforesaid embodiment, the controller 4 determines whether a driving force increase instruction is output based on signal from the vehicle speed sensor 36 as a vehicle speed detecting part for detecting a vehicle speed and the accelerator opening angle sensor 37 as a required driving force detecting part for detecting a required driving force. However, a determination unit is not limited to the aforesaid configuration.
The above embodiment can be combined as desired with one or more of the above modifications. The modifications can also be combined with one another.
According to the present invention, it is possible to increase a driving force during reverse traveling in EV mode by means of a simple configuration.
Above, while the present invention has been described with reference to the preferred embodiments thereof, it will be understood, by those skilled in the art, that various changes and modifications may be made thereto without departing from the scope of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2019-033581 | Feb 2019 | JP | national |
