JP5090947B2 - Control device for hybrid vehicle - Google Patents

Description

  The present invention relates to a control device suitable for a hybrid vehicle.

  In recent years, hybrid vehicles equipped with an engine and a motor generator have been proposed for the purpose of saving fuel for driving the engine, reducing noise caused by engine rotation, and reducing exhaust gas generated by fuel combustion. Yes. This hybrid vehicle is configured to run the vehicle by controlling the engine or the motor generator based on the running state of the vehicle.

  As an example of such a hybrid vehicle, there is a hybrid vehicle having a configuration in which a motor generator is provided on an output shaft of an engine and a transmission is connected via a torque converter. Since the torque converter connects the engine and the transmission via a fluid coupling such as oil, a rotational speed difference occurs between the input shaft and the output shaft of the torque converter, and the transmission efficiency of the driving force can be deteriorated. Therefore, the torque converter is provided with a friction engagement element such as a lock-up clutch in order to mechanically connect the input shaft and the output shaft.

  For example, the following Patent Document 1 describes a technique for setting the engagement force of the lockup clutch temporarily high to quickly reduce the engine speed when performing the deceleration slip control of the lockup clutch. . Patent Document 2 describes a technique for performing energy regeneration during deceleration traveling in a hybrid vehicle including an engine, a motor generator, a torque converter having a lock-up clutch, and a transmission mechanism. Patent Document 3 includes an engine, a motor generator, a torque converter, and a clutch, and applies the power of the motor generator to the engine so as to reduce the difference between the engine speed and the turbine speed of the torque converter by releasing the clutch. The technology to do is described.

Japanese Laid-Open Patent Publication No. 2-163666 JP 2006-153041 A JP 2006-153284 A

  However, in the technique described in Patent Document 1, although the engine speed is decreased more quickly than in the slip control in a state where the lockup clutch engagement force is low, the lockup clutch engagement force is high. As a result, the clutch facing is worn and the durability is lowered.

  Also, during deceleration slip control, if the rotational speed difference between the engine output shaft speed (torque converter input shaft speed) and the torque converter output shaft speed is close to 0, the clutch facing is applied to the front cover. There is a problem that it becomes easy to bite. Although the technique described in Patent Document 1 solves this problem by reducing the fastening force of the lock-up clutch, the rotational speed of the engine output shaft (the rotational speed of the input shaft of the torque converter) and As long as the rotational speed difference with the rotational speed of the output shaft of the torque converter is in the vicinity of 0, the clutch facing is still in the state of being bitten by the front cover, and it cannot be said that the problem has been solved sufficiently.

  The present invention has been made to solve the above-described problems, and provides a control device for a hybrid vehicle capable of suppressing the progress of wear of the clutch facing and preventing the clutch facing from biting the front cover. The issue is to provide.

In one aspect of the present invention, a control device for a hybrid vehicle applied to a hybrid vehicle having a torque converter having a lock-up clutch and an engine and a motor generator connected to an input shaft of the torque converter The control means comprises a control means for performing slip control of the lock-up clutch and reducing the rotational speed of the input shaft of the torque converter by the regenerative braking torque of the motor generator , the control means comprising: The value obtained by subtracting the rotational speed of the output shaft of the torque converter from the rotational speed of the output shaft of the torque converter after the value obtained by subtracting the rotational speed of the output shaft of the torque converter from a rotational speed is smaller than a predetermined value is Until the predetermined value or more, the torque converter Than when the value obtained by subtracting the rotational speed of the output shaft of the torque converter from the rotational speed of the input shaft of is the predetermined value or reduces the regenerative braking torque.

The above hybrid vehicle control device is applied to a hybrid vehicle having an engine, a torque converter, and a motor generator, and has control means such as an ECU (Electronic Control Unit), for example. The torque converter has a lockup clutch capable of directly fastening the input shaft and the output shaft. The engine and the motor generator are connected to an input shaft of the torque converter. The control means performs slip control of the lockup clutch during deceleration and reduces the rotational speed of the input shaft of the torque converter by the regenerative braking torque of the motor generator. By doing so, it is possible to shorten the time during which the rotational speed difference between the input shaft and the output shaft in the torque converter is relatively large, and to suppress the progress of facing wear of the lockup clutch. it can. Further, since the lock-up clutch is slip-controlled, even when compared with the method described in Patent Document 1 in which the engagement force of the lock-up clutch is increased to reduce the engine speed, the wear of the lock-up clutch facing is reduced. Can be suppressed.
In the hybrid vehicle control device described above, the control means is configured such that the value obtained by subtracting the rotational speed of the output shaft of the torque converter from the rotational speed of the input shaft of the torque converter becomes smaller than a predetermined value, and The value obtained by subtracting the rotation speed of the output shaft of the torque converter from the rotation speed of the input shaft of the torque converter until the value obtained by subtracting the rotation speed of the input shaft of the torque converter from the rotation speed reaches a predetermined value or more. The regenerative braking torque is reduced as compared with the above. By doing in this way, the shock which generate | occur | produces when the facing of a lockup clutch bites into a converter cover can be suppressed.

In another aspect of the control apparatus for a hybrid vehicle, the amount by which the regenerative braking torque is reduced is the magnitude of the torque generated on the input shaft of the torque converter when the facing meshes with the converter cover in the lockup clutch. It is decided based on.

  A preferred embodiment of the control apparatus for a hybrid vehicle described above includes engagement means connected between an output shaft of the engine and an input shaft of the torque converter, and the control means is configured to lock the lock during deceleration. In addition to performing slip control of the up-clutch, the engaging means is released or slipped until the rotational speed of the input shaft of the torque converter and the rotational speed of the engine are smaller than the rotational speed of the output shaft of the torque converter. The engaging means is, for example, a clutch. This also shortens the time during which the rotational speed difference between the input shaft and the output shaft in the torque converter is relatively large.

  A control device for a hybrid vehicle applied to a hybrid vehicle having a torque converter having a lock-up clutch, and an engine and a motor generator connected to an input shaft of the torque converter, wherein the lock-up clutch is used during deceleration. And control means for reducing the rotational speed of the input shaft of the torque converter by the regenerative braking torque of the motor generator. By doing so, it is possible to shorten the time during which the rotational speed difference between the input shaft and the output shaft in the torque converter is relatively large, and to suppress the progress of facing wear of the lockup clutch. it can.

  Preferred embodiments of the present invention will be described below with reference to the drawings.

[First Embodiment]
FIG. 1 shows a schematic configuration of a hybrid vehicle according to the first embodiment. The hybrid vehicle shown in FIG. 1 includes an engine 1, a motor generator MG, a torque converter 2, and an automatic transmission mechanism 3. Engine 1 and motor generator MG correspond to a drive source of the hybrid vehicle and are connected in series. The torque converter 2 and the automatic transmission mechanism 3 are connected to these drive sources. Specifically, engine 1 and motor generator MG are connected to the input shaft of torque converter 2. The output shaft of the torque converter 2 is connected to the input shaft of the automatic transmission mechanism 3. The output shaft 5 of the automatic transmission mechanism 3 is connected to drive wheels (not shown). Therefore, the driving force from the engine 1 and the motor generator MG is alternatively or jointly changed through the torque converter 2 and the automatic transmission mechanism 3 and transmitted to the driving wheels, and the hybrid vehicle is driven to travel.

  Further, when the accelerator pedal (not shown) is released during traveling and the vehicle decelerates, the driving force from the driving wheels is transmitted to the driving source via the automatic transmission mechanism 3 and the torque converter 2. At this time, a braking action by the friction torque of the engine 1 occurs, and power generation is performed by driving the motor generator MG. Since the motor generator MG is connected to the input shafts of the engine 1 and the torque converter 2, when the motor generator MG generates power, the motor generator MG is placed on the output shaft 1a of the engine 1 and the input shaft of the torque converter 2. More regenerative braking torque acts. Therefore, the ECU 10 can change the rotational speed of the engine 1 by controlling the motor generator MG.

  The engine 1 is a heat engine that generates power by burning fuel, and examples thereof include a gasoline engine and a diesel engine. The torque converter 2 is a kind of fluid type power transmission device having a function of transmitting power through oil. The torque converter 2 is configured to be able to fasten and release between the input shaft and the output shaft of the torque converter 2 by a lock-up clutch. In the state where the lock-up clutch is released, the driving force is transmitted between the driving source (engine 1 and motor generator MG) and the automatic transmission mechanism 3 via oil. In a state where the lockup clutch is engaged, the drive source and the automatic transmission mechanism 3 are directly connected, and the driving force from the drive source is directly transmitted to the automatic transmission mechanism 3. The hydraulic control device 4 has a function of adjusting the hydraulic pressure of oil supplied to the torque converter 2.

  An ECU (Electronic Control Unit) 10 has a CPU, ROM, RAM, A / D converter, input / output interface, and the like (not shown), and the engine 1, motor generator MG, hydraulic control based on detection signals from various sensors. The device 4 is controlled. In FIG. 1, an arrow indicated by a one-dot chain line indicates a flow of a control signal supplied from the ECU 10. For example, ECU 10 detects the rotational speeds of engine 1 and motor generator MG based on detection signals from rotational speed sensors (not shown) provided in engine 1 and motor generator MG, respectively. The ECU 10 controls the motor generator MG and the hydraulic control device 4 based on these rotational speeds. The ECU 10 corresponds to the control device for a hybrid vehicle of the present invention and functions as a control means.

  The configuration of the torque converter 2 will be described in detail with reference to FIG. FIG. 2 is a schematic diagram showing the configuration of the torque converter. In FIG. 2, a solid line arrow and a broken line arrow without reference numerals indicate the flow of oil.

  The torque converter 2 mainly includes a lockup clutch 21, a pump impeller 22, a turbine liner 23, and a stator 24. The lockup clutch 21 includes a lockup piston 21 a having a facing 21 b and a converter cover 26.

  Output shafts 1 a and Ma of engine 1 and motor generator MG are connected to input shaft 27 of torque converter 2. Therefore, in the case of the hybrid vehicle according to the first embodiment, the rotational speed of the input shaft 27 of the torque converter 2 matches the rotational speed of the motor generator MG (motor rotational speed) and the rotational speed of the engine 1 (engine rotational speed). . The input shaft 27 of the torque converter 2 is connected to the pump impeller 22 via the converter cover 26. The output shaft 28 of the torque converter 2 is connected to the lockup piston 21 a and the turbine liner 23. The rotational speed of the output shaft 28 of the torque converter 2 matches the turbine rotational speed. The stator 24 has a one-way clutch 25 and has a torque amplification function.

  The release-side oil chamber 31 and the fastening-side oil chamber 32 are connected to the hydraulic control device 4 via a passage 33, and the oil goes back and forth in the passage 33. Based on a control signal from the ECU 10, the hydraulic control device 4 supplies oil hydraulic pressure to a release-side oil chamber 31 between the converter cover 26 and the lockup piston 21 a and a fastening-side oil on the pump impeller 22 side. Switching between the chamber 32 and the oil pressure is adjusted. Note that the passage 33 actually passes through the output shaft 28 of the torque converter 2, but in FIG. 2, the passage 33 is illustrated independently of the output shaft 28 for convenience of explanation.

  When the hydraulic control device 4 supplies the hydraulic pressure to the fastening side oil chamber 32, the hydraulic pressure is drained from the release side oil chamber 31. Therefore, the oil flows in the direction from the fastening side oil chamber 32 toward the release side oil chamber 31 as indicated by the broken arrow. In this case, since the hydraulic pressure in the fastening side oil chamber 32 is larger than the hydraulic pressure in the release side oil chamber 31, the force in the direction indicated by the arrow AW1, that is, the force in the direction in which the lockup piston 21a is pressed against the converter cover 26. Works. That is, a force that increases the fastening force of the lockup clutch 21 is applied. This fastening force is proportional to the hydraulic pressure supplied to the fastening side oil chamber 32.

  Further, when the hydraulic control device 4 supplies the hydraulic pressure to the release side oil chamber 31, the hydraulic pressure is drained from the fastening side oil chamber 32. Therefore, the oil flows in a direction from the release side oil chamber 31 toward the fastening side oil chamber 32 as indicated by a solid line arrow. In this case, the hydraulic pressure in the release-side oil chamber 31 is greater than the hydraulic pressure in the engagement-side oil chamber 32. Therefore, the force in the direction indicated by the arrow AW2, that is, the force in the direction in which the lockup piston 21a is pulled away from the converter cover 26. Works. That is, the force which weakens the fastening force of the lockup clutch 21 acts.

  Therefore, the ECU 10 can adjust the fastening force of the lockup clutch 21 by controlling the hydraulic control device 4 and adjusting the hydraulic pressure supplied to the release side oil chamber 31 or the engagement side oil chamber 32. Specifically, the ECU 10 controls the hydraulic pressure control device 4 to adjust the hydraulic pressure supplied to the release-side oil chamber 31 or the engagement-side oil chamber 32, whereby the oil pressure of the release-side oil chamber 31 and the engagement-side oil chamber are adjusted. 32 can change the magnitude relationship between the hydraulic pressures 32 and realize an engaged state in which the lock-up clutch 21 is engaged and a converter state in which the lock-up clutch 21 is released. it can.

  In the intermediate region between the engaged state and the converter state of the lockup clutch 21, the ECU 10 supplies a control signal to the hydraulic control device 4 to adjust the hydraulic pressure of the release side oil chamber 31 or the hydraulic pressure of the engagement side oil chamber 32. By doing so, slip control is performed in which the facing 21b of the lockup piston 21a and the converter cover 26 are slid (slip state). For example, the lock-up clutch 21 is controlled to be in a slip state (deceleration slip control) when the vehicle depressing the accelerator pedal is decelerated (power off).

  Here, when the transition from acceleration to deceleration is performed from the converter state, the engine speed that is higher than the turbine speed during acceleration is lower than the turbine speed during deceleration slip control. In the deceleration transition period, the lock-up clutch 21 is controlled to the slip state until the difference between the engine speed and the turbine speed decreases from a relatively large state to a predetermined feedback control value. Therefore, the facing 21b of the lockup clutch 21 takes a long time to slip under a relatively large difference between the engine speed and the turbine speed, that is, the rotational speed of the input shaft 27 in the torque converter 2. The slipping time becomes longer under the condition where the rotational speed difference between the output shaft 28 and the rotational speed of the output shaft 28 is relatively large, and the wear progresses to deteriorate the durability.

  Further, at the time of this deceleration slip control, the engine speed and the turbine speed are reversed, so that a point where this speed difference becomes 0 is passed during the transition. In other words, the torque converter 2 passes the point where the rotational speed difference between the input shaft 27 and the output shaft 28 becomes zero. Thus, in the vicinity where the difference in rotational speed between the input shaft 27 and the output shaft 28 in the torque converter 2 becomes zero, the friction coefficient between the facing 21b and the oil increases rapidly. For this reason, when the rotational speed difference between the input shaft 27 and the output shaft 28 in the torque converter 2 is close to 0, the facing 21b is easily engaged with the converter cover 26 even if the fastening force of the lockup clutch 21 is small. Become. When the facing 21b is engaged with the converter cover 26, the lockup clutch 21 is suddenly engaged, and a shock is generated.

  Therefore, in the hybrid vehicle control apparatus according to the first embodiment, the ECU 10 performs the slip control of the lockup clutch 21 during deceleration, and uses the regenerative braking torque of the motor generator MG to generate the engine speed, that is, the torque converter. The rotational speed of the second input shaft 27 is reduced. Thereby, the time in which the rotational speed difference between the input shaft 27 and the output shaft 28 in the torque converter 2 is relatively large can be shortened. Further, the ECU 10 determines whether the rotational speed difference between the engine rotational speed and the turbine rotational speed is equal to or greater than a predetermined value, that is, the rotational speed of the input shaft 27 of the torque converter 2 and the rotational speed of the output shaft 28 of the torque converter 21. It is assumed that the engine speed, that is, the rotational speed of the input shaft 27 of the torque converter 2 is reduced at a constant rate until the rotational speed difference becomes a predetermined value or more. Thereby, the shock which generate | occur | produces when the facing 21b bites into the converter cover 26 can be suppressed. This will be specifically described below with reference to FIG.

  FIGS. 3A to 3C show rotation speeds (engine rotation speed and turbine rotation speed), lockup engagement force (engagement force of lockup clutch 21), and MG torque (regenerative braking torque of motor generator MG), respectively. Is a graph showing a change with respect to time.

  As shown in FIGS. 3 (a) and 3 (b), since the converter is in the acceleration operation region, there is a relatively large rotational speed difference between the engine rotational speed and the turbine rotational speed. When the accelerator pedal is returned in this state, the throttle valve is fully closed and deceleration operation is started. In FIG. 3, the time when the deceleration operation starts is shown as time t1. When deceleration slip control (feedback control) is started at the same time as the deceleration starts, the engine speed decreases slowly, and thus a state where the rotational difference between the engine speed and the turbine speed is relatively large continues for a long time. For this reason, as described above, the facing 21b of the lockup clutch 21 slips under a large rotational speed difference between the input shaft 27 and the output shaft 28 in the torque converter, and wear progresses. Endurance decreases.

  In contrast, in the first embodiment, after starting deceleration, the ECU 10 temporarily locks the lock-up clutch 21 between the time t1 and t4 as shown in FIG. 3, the motor generator MG is controlled to regenerate braking torque with respect to the output shaft 1 a of the engine 1 as shown in FIG. To reduce the engine speed. Since the engine rotational speed matches the rotational speed of the input shaft 27 of the torque converter 2, the control for reducing the engine rotational speed is also control for reducing the rotational speed of the input shaft 27 of the torque converter 2.

  As shown in FIG. 3A, this control (hereinafter referred to as “engine speed reduction control”) is performed by reducing the engine speed from a state where the engine speed is higher than the turbine speed, It is executed until the rotational speed and the turbine rotational speed are reversed. Thus, by forcibly reducing the engine speed by the regenerative braking torque of the motor generator MG, the time during which the speed difference between the engine speed and the turbine speed is large, that is, torque The time during which the rotational speed difference between the input shaft 27 and the output shaft 28 in the converter 2 is large can be shortened, and the progress of wear of the facing 21b of the lockup clutch 21 can be suppressed.

  Further, when the engine speed reduction control described above is performed, the engine speed and the turbine speed are reversed, so that a point Sp where the speed difference becomes 0 is passed during the transition. As described above, in the vicinity of the point Sp at which the rotational speed difference becomes 0, the friction coefficient between the facing 21b and the oil increases rapidly. Therefore, when the rotational speed difference is in the vicinity of 0, even if the fastening force of the lockup clutch 21 is a small fastening force, the facing 21b is likely to be engaged with the converter cover 26 and a shock is likely to occur.

  On the other hand, in the first embodiment, when the engine speed is larger than the turbine speed, the ECU 10 has a difference between the engine speed and the turbine speed that is smaller than a predetermined value (FIG. 3). In other words, at time t2), the motor generator MG is controlled to change the regenerative braking torque that acts on the output shaft 1a of the engine 1, that is, the input shaft 27 of the torque converter 2, and thereby the engine speed. That is, the rotational speed of the input shaft 27 of the torque converter 2 is decreased at a constant rate.

  Specifically, the ECU 10 controls the motor generator MG to reduce the regenerative braking torque acting on the output shaft 1a of the engine 1 and the input shaft 27 of the torque converter 2 as shown in FIG. Let The magnitude of the decrease in the regenerative braking torque is the magnitude of the torque generated on the input shaft 27 of the torque converter 2 when the facing 21b is engaged with the converter cover 26.

  That is, the ECU 10 determines the magnitude of the torque generated on the input shaft of the torque converter 2 when the facing 21b is engaged with the converter cover 26 when the difference between the engine speed and the turbine speed is smaller than a predetermined value. The regenerative braking torque is reduced in advance by that amount. Thus, even when the facing 21b is engaged with the converter cover 26, the engine speed, that is, the rotational speed of the input shaft 27 of the torque converter 2 can be reduced at a constant rate. It is possible to suppress a shock that occurs when 21b bites the converter cover 26. This control is executed after the engine speed and the turbine speed are reversed and until the speed difference between the turbine speed and the engine speed reaches a predetermined value or more. Note that the predetermined value is equal to the converter cover 26 of the facing 21b when the rotational speed difference between the engine rotational speed and the turbine rotational speed (the rotational speed difference between the input shaft 27 and the output shaft 28 in the torque converter 2) becomes smaller than this value. The value is such that biting occurs. In other words, the value is such that the friction coefficient between the facing 21b and the oil increases rapidly. The predetermined value is obtained in advance by experiments or the like and recorded in a ROM or the like.

  The predetermined value varies depending on the aging of the facing 21b and oil. Therefore, the ECU 10 may change the predetermined value based on a change in the engine speed in addition to the control described above. For example, when the ECU 10 determines that the facing 21b is engaged with the converter cover 26 based on a change in the engine speed or the like before the speed difference between the engine speed and the turbine speed becomes smaller than a predetermined value. The rotational speed difference at that time may be set as a new predetermined value.

  The ECU 10 controls the motor generator MG when the rotational speed difference between the turbine rotational speed and the engine rotational speed exceeds a predetermined value (time t3 in FIG. 3), so that the turbine rotational speed and the engine rotational speed are controlled. After adjusting the regenerative braking torque so that the rotational speed difference from the engine becomes a constant value, the engaging force of the lock-up clutch 21 is made larger than that during engine speed reduction control to perform deceleration slip control (FIG. 3). In other words, time t4).

  According to the first embodiment described above, slip control of the lockup clutch 21 is performed at the time of deceleration, and the engine speed, that is, the rotation of the input shaft 27 of the torque converter 2 is determined by the regenerative braking torque of the motor generator MG. The number will be reduced. By doing in this way, the time in which the rotation speed difference between the engine rotation speed and the turbine rotation speed is relatively large can be shortened. In other words, it is possible to shorten the time during which the rotational speed difference between the input shaft 27 and the output shaft 28 in the torque converter 2 is relatively large. Thereby, progress of wear of the facing 21b of the lockup clutch 21 can be suppressed. Further, while the engine speed reduction control is being performed, the lockup clutch 21 is in the slip state or the converter state in which the engagement force is relatively small. Therefore, the engagement force of the lockup clutch 21 is increased and the engine is increased. Compared with the method of reducing the rotational speed (see Patent Document 1), the progress of wear of the facing 21b of the lockup clutch 21 can be suppressed.

  Furthermore, according to the first embodiment, during the engine speed reduction control, the rotational speed difference between the engine rotational speed and the turbine rotational speed, that is, the rotational speed difference between the input shaft 27 and the output shaft 28 in the torque converter 2 is It is assumed that the engine speed, that is, the rotational speed of the input shaft 27 of the torque converter is decreased at a constant rate until the predetermined value or more is reached. Thereby, the shock which generate | occur | produces when the facing 21b bites into the converter cover 26 can be suppressed.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. FIG. 4 shows a schematic configuration of the hybrid vehicle according to the second embodiment. Regarding the components of the hybrid vehicle according to the second embodiment shown in FIG. 4, the same components as those of the hybrid vehicle according to the first embodiment shown in FIG. . Moreover, the arrow shown with a dashed-dotted line has shown the flow of the control signal from ECU10. Further, the configuration of the torque converter 2 shown in FIG. 4 has the same configuration as that shown in FIG. Therefore, the reference numerals used in FIG. 2 are also used for the components of the torque converter 2.

  In the hybrid vehicle according to the second embodiment, unlike the hybrid vehicle according to the first embodiment, the clutch 6 is provided between the output shaft 1 a of the engine 1 and the input shaft 27 of the torque converter 2. Transmission and disconnection of torque between the engine 1 and the torque converter 2 are performed by engaging and releasing the clutch 6. The output shaft Ma of the motor generator MG is connected to the input shaft 27 of the torque converter 2. Therefore, in a state where the clutch 6 is released, the output shaft Ma of the motor generator MG is not connected to the output shaft 1a of the engine 1, but is connected only to the input shaft 27 of the torque converter 2. Therefore, the regenerative braking torque of motor generator MG acts only on input shaft 27 of torque converter 2, and the rotational speed of input shaft 27 of torque converter 2 matches the motor rotational speed of motor generator MG. Engagement and release of the clutch 6 are controlled by a control signal from the ECU 10.

  In the hybrid vehicle according to the second embodiment, the ECU 10 performs slip control of the lockup clutch 21 during deceleration, and the rotational speed of the input shaft 27 and the engine rotational speed of the torque converter 2 are turbine rotational speeds, that is, The clutch 6 is released or slipped until the rotational speed of the output shaft 28 of the torque converter 2 becomes smaller. This will be specifically described below with reference to FIG.

  5 (a) to 5 (c) show the time for each of the rotational speed (engine rotational speed, motor rotational speed, turbine rotational speed), lock-up fastening force (fastening force of the lock-up clutch 21), and clutch 6 state. It is a graph which shows the change with respect to.

  In the second embodiment, the ECU 10 temporarily engages the lockup clutch 21 between the time ta1 and ta2 after the start of deceleration, as shown in FIG. The slip state is set to a lower slip state or the converter state, and the clutch 6 is released from the engaged state or slipped as shown in FIG. The ECU 10 can change the engine speed and the motor speed at different speeds by releasing or slipping the clutch 6 at the deceleration operation start time ta1. The ECU 10 reduces the motor speed and the engine speed from time ta1 to time ta2 (FIG. 5A). Specifically, the ECU 10 disengages or slips the clutch 6 and quickly decreases the engine speed due to the friction of the engine 1 itself. Further, ECU 10 controls motor generator MG to reduce the motor rotation speed. Since the motor rotational speed matches the rotational speed of the input shaft 27 of the torque converter 2, the control for reducing the motor rotational speed is also the control for reducing the rotational speed of the input shaft 27 of the torque converter 2.

  In the above-described control, the engine rotational speed and the motor rotational speed (the rotational speed of the input shaft 27 of the torque converter 2) are larger than the turbine rotational speed (the rotational speed of the output shaft 28 of the torque converter 2). The process is executed until the motor speed decreases and the engine speed, the motor speed, and the turbine speed are reversed. Even in this case, the time during which the rotational speed difference between the input shaft 27 and the output shaft 28 in the torque converter 2 is relatively large can be shortened, and the progress of wear of the facing 21b of the lockup clutch 21 is suppressed. be able to.

  Further, when the motor rotational speed is larger than the turbine rotational speed, when the rotational speed difference between the motor rotational speed and the turbine rotational speed is smaller than a predetermined value, the motor rotational speed is the rotation of the input shaft 27 of the torque converter 2. Therefore, the rotational speed difference between the input shaft 27 and the output shaft 28 in the torque converter 2 is also smaller than a predetermined value. Accordingly, also in this case, the facing 21b may be engaged with the converter cover 26.

  Therefore, in the second embodiment, the ECU 10 controls the motor generator MG to control the input shaft 27 of the torque converter 2 when the rotational speed difference between the motor rotational speed and the turbine rotational speed is smaller than a predetermined value. By changing the regenerative braking torque acting in this manner, the motor rotation speed, that is, the rotation speed of the input shaft 27 of the torque converter 2 is reduced at a constant rate. Thereby, the shock which generate | occur | produces when the facing 21b bites into the converter cover 26 can be suppressed. This control is executed until the rotational speed difference between the motor rotational speed and the turbine rotational speed becomes a predetermined value or more after the motor rotational speed and the turbine rotational speed are reversed. This predetermined value is also applied to the converter cover 26 of the facing 21b when the rotational speed difference between the motor rotational speed and the turbine rotational speed (the rotational speed difference between the input shaft 27 and the output shaft 28 in the torque converter 2) becomes smaller than this value. It is a value that causes the biting of. The predetermined value is obtained in advance by experiments or the like and recorded in a ROM or the like.

  The ECU 10 controls the motor generator MG, and when the rotational speed difference between the motor rotational speed and the turbine rotational speed is equal to or larger than a predetermined value and the motor rotational speed matches the engine rotational speed (in FIG. 3, time ta2 ), The clutch 6 is controlled to bring the clutch 6 into an engaged state. Then, the ECU 10 adjusts the regenerative braking torque so that the rotational speed difference between the turbine rotational speed and the engine rotational speed becomes a constant value, and then increases the fastening force of the lockup clutch 21 to perform the deceleration slip control. .

  According to the second embodiment described above, slip control of the lockup clutch 21 is performed at the time of deceleration, and the motor rotation speed (the rotation speed of the input shaft 27 of the torque converter 2) and the engine rotation speed are the turbine rotation speed. The clutch 6 is released or slipped until it becomes smaller than the number (the rotational speed of the output shaft 28 of the torque converter 2). This also shortens the time during which the rotational speed difference between the input shaft 27 and the output shaft 28 in the torque converter 2 is relatively large, and suppresses the progress of wear of the facing 21b of the lockup clutch 21. it can.

It is a figure showing the schematic structure of the hybrid vehicle concerning a 1st embodiment. It is a schematic diagram which shows the structure of a torque converter. It is a graph which shows the change with respect to time about each of rotation speed, lockup fastening force, and regenerative braking torque. It is a figure which shows schematic structure of the hybrid vehicle which concerns on 2nd Embodiment. It is a graph which shows the change with respect to time about each of a rotation speed, lockup fastening force, and the state of a clutch.

Explanation of symbols

MG Motor generator 1 Engine 2 Torque converter 3 Automatic transmission mechanism 4 Hydraulic control device 5 Output shaft

Claims (3)

A control device for a hybrid vehicle applied to a hybrid vehicle having a torque converter having a lock-up clutch, and an engine and a motor generator connected to an input shaft of the torque converter,
Control means for performing slip control of the lock-up clutch during deceleration and reducing the rotational speed of the input shaft of the torque converter by the regenerative braking torque of the motor generator ,
The control means determines the torque from the rotational speed of the output shaft of the torque converter after a value obtained by subtracting the rotational speed of the output shaft of the torque converter from the rotational speed of the input shaft of the torque converter becomes smaller than a predetermined value. The value obtained by subtracting the rotational speed of the output shaft of the torque converter from the rotational speed of the input shaft of the torque converter until the value obtained by subtracting the rotational speed of the input shaft of the converter reaches the predetermined value or more. The control device for a hybrid vehicle , wherein the regenerative braking torque is reduced as compared with the above . 2. The hybrid vehicle according to claim 1 , wherein the amount by which the regenerative braking torque is reduced is determined based on a magnitude of torque generated on an input shaft of the torque converter when a facing is engaged with a converter cover in the lockup clutch. Control device. Engagement means connected between the output shaft of the engine and the input shaft of the torque converter;
The control means performs slip control of the lockup clutch during deceleration, and until the rotational speed of the input shaft of the torque converter and the rotational speed of the engine become smaller than the rotational speed of the output shaft of the torque converter. The hybrid vehicle control device according to claim 1, wherein the engaging means is released or slipped.

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