JP7635570B2 - Vehicle drive device control device - Google Patents

Description

The present invention relates to a control device for a vehicle drive system.

Patent Document 1 discloses a power transmission device equipped with a fluid coupling that transmits engine power to the transmission, a lock-up clutch for mechanically connecting and disconnecting the fluid coupling, and a shift clutch that is provided between the fluid coupling and the transmission and is connected and disconnected in response to a shift operation of the transmission, in which the lock-up clutch is connected before the shift clutch when the driver performs an unusual starting operation. The power transmission device described in Patent Document 1 can prevent poor connection of the lock-up clutch.

JP 2005-76667 A

However, in the power transmission device described in Patent Document 1, control related to engagement of the shift clutch cannot be performed until the lock-up clutch is engaged, which lengthens the time required for shifting. If the time required for shifting becomes too long, for example, when accelerating from a standstill, acceleration may become sluggish, which may deteriorate drivability.

The present invention was made in consideration of the above-mentioned circumstances, and aims to provide a control device for a vehicle drive unit that can smoothly engage the shift clutch and perform smooth gear changes without impairing drivability, even when the lock-up clutch is not engaged.

To achieve the above object, the present invention provides a control device for a vehicle drive device, which includes a torque converter with a lock-up clutch connected to an engine, a speed change mechanism that changes the rotation of the engine at a speed change ratio corresponding to the gear stage and outputs the changed speed, a speed change clutch that is provided between the torque converter and the speed change mechanism and can be switched between an engaged state for transmitting power and a disconnected state for disconnecting power, and a clutch actuator that automatically operates the speed change clutch, and includes a control unit that controls the drive of the clutch actuator, and the control unit is configured to calculate a target clutch torque based on a turbine required torque, which is a required value of the torque output from the torque converter, when a speed change is performed to switch the gear stage with the lock-up clutch released, and to control the clutch actuator to engage the speed change clutch based on the target clutch torque.

The present invention provides a control device for a vehicle drive unit that can smoothly engage the shift clutch and perform smooth gear changes without compromising drivability, even when the lock-up clutch is not engaged.

FIG. 1 is a schematic diagram of a vehicle equipped with a control device for a vehicle drive device according to an embodiment of the present invention. FIG. 2 is a conceptual diagram of a power transmission system of a vehicle equipped with a control device for a vehicle drive device according to one embodiment of the present invention. FIG. 3 is a block diagram showing a flow of calculation of a target clutch torque in a control device for a vehicle drive device according to one embodiment of the present invention. FIG. 4 is an example of a map referenced by the control device for a vehicle drive system according to one embodiment of the present invention, and is a characteristic map showing the relationship between the speed ratio and the torque ratio. FIG. 5 is an example of a timing chart showing transitions of the engine rotation speed, turbine rotation speed, and clutch rotation speed during gear shifting in a vehicle equipped with a control device for a vehicle drive system according to one embodiment of the present invention.

The control device for a vehicle drive device according to one embodiment of the present invention is a control device for a vehicle drive device that includes a torque converter with a lock-up clutch connected to an engine, a speed change mechanism that changes the rotation of the engine at a speed change ratio according to the gear stage and outputs it, a speed change clutch that is provided between the torque converter and the speed change mechanism and can be switched between an engaged state that transmits power and a disconnected state that disconnects power, and a clutch actuator that automatically operates the speed change clutch. The control device includes a control unit that controls the drive of the clutch actuator, and when performing a gear change to switch the gear stage with the lock-up clutch released, the control unit calculates a target clutch torque based on a turbine request torque, which is a request value for the torque output from the torque converter, and controls the clutch actuator to engage the speed change clutch based on the target clutch torque. As a result, the control device for a vehicle drive device according to one embodiment of the present invention can smoothly engage the speed change clutch without impairing drivability even when the lock-up clutch is not engaged, thereby performing a smooth gear change.

Below, a vehicle equipped with a control device for a vehicle drive system according to one embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the vehicle 1 includes an engine 2 as an internal combustion engine, an automatic transmission 3 as a vehicle drive device, drive wheels 4, and a control device 10.

The engine 2 has multiple cylinders. In this embodiment, the engine 2 is configured to perform a series of four strokes for each cylinder, consisting of an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke. The engine 2 is the power source for the vehicle 1.

The automatic transmission 3 is provided in the power transmission path between the engine 2 and the drive wheels 4. The automatic transmission 3 has a torque converter 30, a speed change mechanism 31, a speed change clutch 32, and a clutch actuator 33.

The torque converter 30 is a so-called torque converter with a lock-up clutch, which has a lock-up clutch 35. The torque converter 30 is provided in the power transmission path between the engine 2 and the variable speed clutch 32, and transmits power via fluid and outputs it to the turbine shaft 36.

The variable speed clutch 32 is connected to the turbine shaft 36. The torque converter 30 amplifies the torque (driving force) input from the crankshaft 21 of the engine 2 by the rotation difference through a fluid, and outputs it to the turbine shaft 36 and the variable speed clutch 32. The output of the torque converter 30 is then transmitted to the transmission mechanism 31 via the turbine shaft 36 and the variable speed clutch 32.

The inside of the torque converter 30 is divided into an apply chamber and a release chamber (not shown) by the lock-up clutch 35. Hydraulic oil is supplied to the apply chamber or the release chamber, and the operating state of the lock-up clutch 35 is switched depending on the hydraulic pressure (hydraulic oil pressure) of the supplied hydraulic oil.

The lock-up clutch 35 is provided in the torque converter 30, and its operating state can be switched between a connected state (hereinafter referred to as "direct connection") in which the crankshaft 21 and turbine shaft 36 of the engine 2 rotate together to transmit power, and a released state in which the direct connection between the crankshaft 21 and turbine shaft 36 is released and the crankshaft 21 and turbine shaft 36 transmit power via a fluid (hydraulic oil).

The lock-up clutch 35 is switched to the engaged state by supplying hydraulic oil pressure (hereinafter, this hydraulic oil pressure is referred to as "engagement hydraulic oil pressure") to the apply chamber and discharging hydraulic oil from the release chamber. Conversely, the lock-up clutch 35 is switched to the released state by supplying hydraulic oil pressure (hereinafter, this hydraulic oil pressure is referred to as "release hydraulic oil pressure") to the release chamber and discharging hydraulic oil from the apply chamber.

The speed change mechanism 31 is provided in the power transmission path between the speed change clutch 32 and the drive wheels 4, and has an input shaft 37 connected to the speed change clutch 32, and an output shaft 38 connected to the drive wheels 4 via a differential (not shown). The speed change mechanism 31 converts the driving force input from the speed change clutch 32 to the input shaft 37, changes the rotational speed, and outputs it from the output shaft 38.

The transmission mechanism 31 changes the rotation of the engine 2, which is output from the engine 2 and transmitted to the input shaft 37, at a gear ratio corresponding to one of a plurality of gears selected from among a plurality of gears described below, and outputs the changed rotation to the output shaft 38. The rotation and driving force output to the output shaft 38 are transmitted to the drive wheels 4 via a differential (not shown).

The transmission mechanism 31 is configured to be capable of forming multiple gear stages with different gear ratios by multiple gear pairs with different gear ratios. The gear stages in the transmission mechanism 31 are automatically switched by a shift actuator (not shown). In detail, the control device 10 determines whether a gear shift is necessary by referring to a gear shift map based on the vehicle speed and the amount of depression of the accelerator pedal, and outputs a gear shift command to the shift actuator. The shift actuator then operates upon receiving the gear shift command to perform the gear shift.

The variable speed clutch 32 is provided in the power transmission path between the torque converter 30 and the speed change mechanism 31. The variable speed clutch 32 has a clutch wheel disc 32a connected to rotate integrally with the turbine shaft 36, and a clutch disc 32b connected to rotate integrally with the input shaft 37 of the speed change mechanism 31.

The variable speed clutch 32 is a dry single-plate clutch that can be switched between an engaged state in which the clutch disc 32b is pressed against the clutch wheel disc 32a to rotate together with the clutch wheel disc 32a to transmit power, and a disconnected state in which the clutch disc 32b is separated from the clutch wheel disc 32a to interrupt the power transmission between the clutch wheel disc 32a and the clutch disc 32b. In other words, the variable speed clutch 32 transmits power between the turbine shaft 36 and the input shaft 37 in the engaged state, and interrupts the power transmission between the turbine shaft 36 and the input shaft 37 in the disconnected state.

The operation of switching the variable-speed clutch 32 between an engaged state and a disengaged state (hereinafter referred to as "clutch operation") is performed automatically by the clutch actuator 33.

The clutch actuator 33 is electrically connected to the control device 10 and performs clutch operation of the speed change clutch 32 based on commands from the control device 10. Specifically, the clutch actuator 33 moves a release bearing (not shown) in the axial direction of the input shaft 37 using a release fork or the like, and the release bearing elastically deforms the diaphragm spring of the clutch wheel disc 32a to disengage the speed change clutch 32. The clutch actuator 33 also moves the release bearing from the disengaged position in the opposite direction to when the disengaged state is entered, releasing the diaphragm spring from its elastic deformation and placing the speed change clutch 32 in an engaged state.

The control device 10 is composed of a computer unit equipped with a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), flash memory for storing backup data, etc., input ports, and output ports.

The ROM of the computer unit stores various constants, maps, and the like, as well as a program for causing the computer unit to function as the control device 10. In other words, the CPU executes the program stored in the ROM using the RAM as a working area, causing the computer unit to function as the control device 10 in this embodiment.

The control device 10 is connected to various devices such as the shift actuator, clutch actuator 33, and hydraulic control device 40 (not shown), as described above, and various sensors such as a crank angle sensor 50, a turbine rotation speed sensor 51, a clutch rotation speed sensor 52, a clutch position detection sensor 53, a lock-up hydraulic sensor 54, a vehicle speed sensor 55, and an accelerator sensor 56.

The hydraulic control device 40 controls the hydraulic pressure supplied to the lock-up clutch 35 and the clutch actuator 33 of the torque converter 30. The hydraulic control device 40 switches the lock-up clutch 35 between an engaged state and a disengaged state by adjusting the magnitude of the hydraulic pressure supplied to the lock-up clutch 35 based on a command from the control device 10. The hydraulic control device 40 switches the speed-change clutch 32 between an engaged state and a disengaged state by adjusting the magnitude of the hydraulic pressure supplied to the clutch actuator 33 based on a command from the control device 10.

The crank angle sensor 50 detects the rotation angle of the crankshaft 21 (hereinafter referred to as the "crank angle"). The control device 10 calculates the engine rotation speed, which is the rotation speed of the engine 2 (the rotation speed of the crankshaft 21), based on the information indicating the crank angle input from the crank angle sensor 50.

The turbine rotation speed sensor 51 detects the rotation speed of the turbine shaft 36 (hereinafter referred to as the "turbine rotation speed"). The clutch rotation speed sensor 52 detects the rotation speed of the clutch disc 32b and the input shaft 37 (hereinafter referred to as the "clutch rotation speed").

The clutch position detection sensor 53 detects the position of the release bearing in the variable speed clutch 32 or the position of a part such as a release fork that moves in relation to the movement state of the release bearing (hereinafter referred to as the "clutch position"). The clutch position indicates the state of the variable speed clutch 32 (disengaged state/half-clutch state/engaged state), and can also be considered to indicate the magnitude of the torque transmitted by the variable speed clutch 32. The lock-up oil pressure sensor 54 detects the hydraulic oil pressure supplied to the lock-up clutch 35. In this embodiment, an example of detecting the engagement oil pressure acting on the apply chamber is shown, but the oil pressure acting on the apply chamber may be estimated or detected based on the release oil pressure acting on the release chamber. The vehicle speed sensor 55 detects the vehicle speed, which is the speed of the vehicle 1. The accelerator sensor 56 detects the amount of depression of an accelerator pedal (not shown) by the driver. The accelerator sensor 56 may also detect the movement of the throttle valve, which changes in conjunction with the amount of depression of the accelerator pedal.

The control device 10 has a function as a clutch control unit 101 that controls the shift clutch 32 by referring to a map (not shown) that defines the relationship between the clutch position and the clutch transmission torque (hereinafter also referred to as "clutch torque") based on the clutch position detected by the clutch position detection sensor 53, specifically, that controls the clutch actuator 33 so that the shift clutch 32 is operated. The clutch control unit 101 in this embodiment constitutes a control unit.

When shifting gears, the control device 10 automatically performs clutch and shift operations by controlling the clutch actuator 33 and the shift actuator so that the shift clutch 32 is switched from an engaged state to a disengaged state, the gear stage in the shift mechanism 31 is changed, and then the shift clutch 32 is switched from a disengaged state to an engaged state.

To perform the above-mentioned gear shift smoothly and without any discomfort (without impairing drivability), it is desirable that the torque input to the gear shift clutch 32 and the clutch torque match when the gear shift is completed.

If the torque input to the shift clutch 32 is greater than the clutch torque, the shift clutch 32 will slip and the engine speed will increase. Conversely, if the torque input to the shift clutch 32 is less than the clutch torque, the shift clutch 32 will not slip and will suddenly engage, causing the engine to stall due to a sudden drop in engine speed or causing a shock to the vehicle body due to the action of the inertia (inertia force) on the engine 2 side.

Therefore, when engaging the shift clutch 32 in conjunction with a gear shift, it is preferable for the control device 10 to set a clutch torque corresponding to the torque input to the shift clutch 32 as a target clutch torque and control the engagement of the shift clutch 32.

When the lock-up clutch 35 is engaged, the crankshaft 21 and the turbine shaft 36 are directly connected, so the "torque input to the shift clutch 32" described above is engine torque. Therefore, when shifting gears with the lock-up clutch 35 engaged, the control device 10 sets the target clutch torque based on the engine required torque, which is the torque required of the engine 2.

In contrast, when the lock-up clutch 35 is released, the crankshaft 21 and the turbine shaft 36 transmit power via the fluid of the torque converter 30, so the engine torque and the turbine torque do not match. For this reason, if the target clutch torque is set based on the engine required torque as described above when shifting gears with the lock-up clutch 35 released, the torque input to the shift clutch 32 and the clutch torque will not match when the shifting gear is completed. In this case, the engine speed may increase or shock may occur as described above, which may impair drivability.

Therefore, in this embodiment, when a gear shift is performed with the lock-up clutch 35 released, the turbine required torque is used for control instead of the engine required torque, and the target clutch torque is set based on the turbine required torque. Specifically, when a gear shift is performed with the lock-up clutch 35 released, the control device 10 calculates the turbine required torque from the engine required torque and the target turbine rotation speed, calculates the target clutch torque based on the calculated turbine required torque, and controls the clutch actuator 33 to engage the gear shift clutch 32 based on the target clutch torque. The method of calculating the target clutch torque will be described later.

The control device 10 functions as a lockup clutch control unit 102 that controls the engagement or disengagement of the lockup clutch 35. For example, when a predetermined lockup condition is met, the control device 10 executes lockup control that controls the hydraulic control device 40 to switch the lockup clutch 35 from a released state to an engaged state.

In this embodiment, the predetermined lockup condition is, for example, when the vehicle speed is equal to or greater than a predetermined vehicle speed. The predetermined lockup condition is not limited to this and may be other conditions, or the state of the gear position and vehicle speed may be the predetermined lockup condition.

(Method of calculating target clutch torque)
Next, a method for calculating a target clutch torque by the control device 10 of this embodiment will be described with reference to FIG. 2 and FIG.

In explaining the method of calculating the target clutch torque, the various parameters in the power transmission system of the vehicle 1 of this embodiment are specifically defined as follows, as shown in FIG. 2. In the following, parameters marked with "*" indicate the target value of the parameter not marked with "*", and parameters marked with "r" indicate the required value of the parameter not marked with "r".

Ne: Engine rotation speed Ne*: Target engine rotation speed Nt: Turbine rotation speed Nt*: Target turbine rotation speed Nc: Clutch rotation speed Te: Engine torque Ter: Engine required torque Ti: Impeller torque Tir: Impeller required torque Tt: Turbine torque Ttr: Turbine required torque Tc: Clutch torque Tc*: Target clutch torque Ie: Engine inertia Ii: Impeller inertia It: Turbine inertia Ic: Clutch inertia

Moreover, other parameters not shown in FIG. 2 are defined as follows.
SR: Speed ratio τ: Torque ratio dωe/dt: Engine rotation change amount (dωt/dt)*: Target turbine rotation change amount dωc/dt: Clutch rotation change amount

The above speed ratio SR is the ratio (Nt*/Ne*) between the target engine rotation speed Ne* and the target turbine rotation speed Nt*. The torque ratio τ is the ratio between the input torque and the output torque of the torque converter 30 (output torque/input torque). The engine rotation change amount dωe/dt is the time-differentiated value of the engine rotation speed Ne. The target turbine rotation change amount (dωt/dt)* is the time-differentiated value of the target turbine rotation speed Nt*. The clutch rotation change amount dωc/dt is the time-differentiated value of the clutch rotation speed Nc.

In addition, in calculating the target clutch torque, the following prerequisites (1) to (3) are satisfied when the gear shift is completed.
(1) Turbine rotation speed = clutch rotation speed (2) Driver requested engine torque = engine requested torque (3) Engine rotation change amount ≒ Turbine rotation change amount = clutch rotation change amount

When the shift is complete, the turbine rotation speed and the clutch rotation speed are synchronized by engaging the shift clutch 32, so the precondition (1) above must be met.

During a gear shift, the gear shift control requests the engine 2 to reduce or increase torque, so there is a difference between the driver requested engine torque calculated from the amount of accelerator pedal depression (accelerator opening) by the driver and the engine requested torque actually requested by the engine 2. However, when the gear shift is completed, the engine requested torque will match the driver requested engine torque in order to prevent a torque step from occurring when the gear shift is completed by making the engine requested torque match or approaching the driver requested engine torque. For this reason, the above precondition (2) must be satisfied when the gear shift is completed.

At the completion of the shift, the turbine rotation speed and the clutch rotation speed match, so the turbine rotation change amount and the clutch rotation change amount have the same value. In contrast, the engine rotation speed does not match the turbine rotation speed because it passes through the torque converter 30. However, the engine rotation change amount does not exactly match the turbine rotation change amount because it passes through the torque converter 30, but since the difference in the rotation speed of the torque converter 30 stabilizes at the completion of the shift, the engine rotation change amount is treated as the same value as the turbine rotation change amount in order to calculate the turbine required torque. In other words, as shown in FIG. 5, the slope (speed of change) of the engine rotation speed Ne at time t3 is almost the same as the slope (speed of change) of each line of the turbine rotation speed Nt and the clutch rotation speed Nc.

When shifting is performed with the lock-up clutch 35 released, the turbine required torque Ttr is used for control instead of the engine required torque Ter, and the target clutch torque Tc* at the completion of the shift (time t3 shown in FIG. 5) is calculated. In detail, the accelerator sensor 56 detects the amount of depression of the accelerator pedal (not shown) by the driver, judges the driver's intention to accelerate, including whether to accelerate or not, and calculates the driving force (target clutch torque Tc*) required at the completion of the shift from the vehicle speed detected by the vehicle speed sensor 55, the engine rotation speed Ne, and the gear stage. As shown in FIG. 3, the control device 10 calculates the inertia torque "(dωe/dt) x (Ii + Ie)" from the engine rotation change amount dωe/dt, the impeller rash Ii, and the engine inertia Ie (step S1). Specifically, the control device 10 calculates the inertia torque "(dωe/dt) x (Ii + Ie)" by multiplying the engine rotation change amount dωe/dt by the sum of the impeller shaving Ii and the engine inertia Ie. The engine rotation change amount dωe/dt here is equivalent to the clutch rotation change amount according to the above preconditions, and the current value is used. In addition, the impeller shaving Ii and the engine inertia Ie use design values or values obtained experimentally.

The control device 10 calculates the impeller required torque Tir by subtracting the inertia torque "(dωe/dt) x (Ii + Ie)" calculated in step S1 from the engine required torque Ter (step S2). The engine required torque Ter here is the engine required torque at the completion of the shift, and therefore becomes the driver required engine torque according to the above preconditions. The impeller required torque Tir is the input torque to the torque converter 30.

The control device 10 calculates the target engine speed Ne* from the target turbine speed Nt* and the impeller required torque Tir calculated in step S2 (step S3). Specifically, the control device 10 calculates the target engine speed Ne* by referring to a conversion map that has been calculated in advance to determine the relationship between the target turbine speed, the impeller required torque, and the target engine speed. The conversion map is stored in the ROM of the control device 10. The target turbine speed Nt* here is the target value of the turbine speed Nt at the completion of the shift, and according to the above assumptions, is the same value as the clutch speed Nc at the completion of the shift. The target turbine speed Nt* is calculated, for example, based on the vehicle speed at the completion of the shift.

The above conversion map is a map calculated based on the characteristic data (capacity coefficient, torque ratio) of the torque converter 30. It is a map of the torque converter input rotation speed (engine rotation speed Ne) at the equilibrium point where the theoretical input torque of the torque converter 30 is balanced with the input torque (impeller torque Ti) that is predetermined for the torque converter 30 and the turbine rotation speed (Nt*).

The theoretical input torque is calculated by multiplying the capacity coefficient by the square of the input rotation speed. Since the capacity coefficient changes based on the speed ratio, the input rotation speed of the torque converter must be changed continuously to calculate the equilibrium point when calculating the conversion map.

The torque converter 30 qualitatively operates only at the equilibrium point. Specifically, since the theoretical input torque is regarded as a load torque relative to the input torque, when the theoretical input torque exceeds the input torque, the input rotation speed (engine rotation speed Ne) of the torque converter decreases, and the theoretical input torque decreases. On the other hand, when the theoretical input torque falls below the input torque, the input rotation speed (engine rotation speed Ne) of the torque converter increases, and the theoretical input torque increases, resulting in a qualitative operation only at the equilibrium point.

Therefore, by referring to a conversion map that maps the theoretical input torque of the torque converter 30 and the torque converter input speed (engine speed Ne) at the balance point between the theoretical input torque of the torque converter 30 and the input torque (impeller torque Ti) at a predetermined input torque (impeller torque Ti) and a predetermined turbine speed (Nt*), the target engine speed Ne* at the balance point can be calculated from the target turbine speed Nt* and the impeller required torque Tir calculated in step S2 (step S3).

The conversion map may be changed depending on environmental factors. For example, the conversion map may be switched according to the oil temperature in the torque converter, which changes the characteristics (capacity coefficient, torque ratio) of the torque converter 30.

The control device 10 calculates the speed ratio SR (=Nt*/Ne*) from the target engine rotation speed Ne* and the target turbine rotation speed Nt* calculated in step S3 (step S4). The control device 10 calculates the torque ratio τ according to the speed ratio SR from the torque converter characteristics (step S5).

The torque converter characteristic is a characteristic that is determined based on the specifications of the torque converter 30, such as the transmission torque capacity. In step S5, specifically, the control device 10 calculates the above-mentioned torque ratio τ from the speed ratio SR calculated in step S4 by referring to the characteristic map shown in FIG. 4. The characteristic map shown in FIG. 4 is a relationship between the speed ratio SR and the torque ratio τ that is experimentally obtained in advance based on the torque converter characteristic of the torque converter 30, and is stored in the ROM of the control device 10.

In this embodiment, by using the characteristic map shown in FIG. 4, the impeller torque can be converted to turbine torque as described below, regardless of the impeller torque, engine rotation speed, etc. For this reason, the characteristic map shown in FIG. 4 can be used in the entire range in which gear shifting is performed. Therefore, the turbine required torque can be calculated even if, for example, the driver further depresses the accelerator pedal or releases the accelerator pedal during gear shifting. In other words, the target clutch torque at the end of gear shifting can be determined.

Next, the control device 10 calculates the turbine required torque Ttr from the impeller required torque Tir calculated in step S2 and the torque ratio τ calculated in step S5 (step S6). Specifically, the control device 10 calculates the turbine required torque Ttr by multiplying the impeller required torque Tir calculated in step S2 by the torque ratio τ calculated in step S5. The turbine required torque Ttr calculated in step S6 is the required value of the torque output from the torque converter 30 and input to the variable speed clutch 32, and is the required value of the turbine torque Tt at the time of completion of the shift (when the variable speed clutch 32 is fully engaged).

The control device 10 calculates the target turbine rotation change amount (dωt/dt)* by time-differentiating the target turbine rotation speed Nt* (step S7). The control device 10 calculates the inertia torque "((dωt/dt)*)×(It+Ic)" from the target turbine rotation change amount (dωt/dt)* calculated in step S7, the turbine inertia It, and the clutch inertia Ic (step S8). Specifically, the control device 10 calculates the inertia torque "((dωt/dt)*)×(It+Ic)" by multiplying the target turbine rotation change amount (dωt/dt)* by the sum of the turbine inertia It and the clutch inertia Ic.

Then, the control device 10 calculates the target clutch torque Tc* based on the turbine required torque Ttr calculated in step S6 and the inertia torque "((dωt/dt)*)×(It+Ic)" calculated in step S8 (step S9). Specifically, the control device 10 calculates the target clutch torque Tc* by subtracting the inertia torque "((dωt/dt)*)×(It+Ic)" calculated in step S8 from the turbine required torque Ttr calculated in step S6. The target clutch torque Tc* calculated in step S9 is the target value of the clutch torque Tc at the completion of the shift. In other words, the target clutch torque Tc* is set so that the clutch torque Tc at the completion of the shift can smoothly respond to the turbine torque Tt that will be input from the turbine shaft 36 to the shift clutch 32 at the completion of the shift. By calculating the turbine torque Tt and setting the target clutch torque Tc*, the shift clutch 32 can be smoothly engaged without impairing drivability.

Next, referring to FIG. 5, we will explain the transitions in engine rotation speed, turbine rotation speed, and clutch rotation speed when shifting gears with the lock-up clutch 35 not engaged in the vehicle 1 of this embodiment.

As shown in FIG. 5, at time t0, the vehicle 1 is accelerating at a specified gear. While the vehicle 1 is accelerating at a specified gear, the variable speed clutch 32 is engaged, so the turbine rotation speed Nt and the clutch rotation speed Nc are synchronized and rising together. In contrast, the engine rotation speed Ne does not match the turbine rotation speed Nt and the clutch rotation speed Nc due to the power transmission via the fluid in the torque converter 30, and is a rotation speed higher than these.

After that, at time t1, shift control is executed and a shift (upshift) from a predetermined gear to a higher gear is initiated. In other words, when shift control is initiated, the shift clutch 32 is switched to a disengaged state and the current power transmission path (gear) is switched to a higher gear. At this time, the clutch rotation speed Nc drops sharply as a synchronizing device (not shown) operates to set the rotation speed to correspond to the vehicle speed. Note that when shift control is executed as described above, the engine torque is suppressed by a torque reduction request. As a result, the engine rotation speed Ne drops gradually.

Then, at time t2, when the gear change in the transmission mechanism 31 is completed, the clutch rotation speed Nc becomes a rotation speed corresponding to the vehicle speed and the gear after the upshift. Also, because the transmission clutch 32 is in a disengaged state and the load on the turbine shaft 36 disappears, the engine rotation speed Ne and the turbine rotation speed Nt become substantially the same rotation speed without any rotation difference. After that, from time t2 onwards, the transmission clutch 32, which is in a disengaged state, is gradually engaged and transitions to an engaged state. At this time, the clutch position of the transmission clutch 32 is controlled so that the clutch torque Tc at the completion of the shift becomes the target clutch torque Tc* calculated by the control device 10. As the transmission clutch 32 is gradually engaged, the driving force is transmitted to the drive wheels 4, the vehicle speed gradually increases, and the clutch rotation speed Nc also gradually increases.

In addition, when the shift clutch 32 is gradually engaged, the clutch torque Tc gradually increases, and the load applied to the turbine shaft 36 from the shift clutch 32 side increases. As a result, the engine rotation speed Ne and the turbine rotation speed Nt gradually decrease after time t2. However, the torque reduction request made to the engine 2 by the shift control gradually decreases and normal engine control is resumed, and because acceleration is in progress, a rotation difference occurs between the engine rotation speed Ne and the turbine rotation speed Nt.

After that, at time t3, when the shift is completed, the shift clutch 32 is fully engaged, so that the turbine rotation speed Nt and the clutch rotation speed Nc are synchronized. At this time, the engine rotation speed Ne does not match the turbine rotation speed Nt and the clutch rotation speed Nc due to the power transmission via the fluid in the torque converter 30, and is a rotation speed higher than these turbine rotation speed Nt and clutch rotation speed Nc. Note that the rate of change of the engine rotation speed Ne at time t3 is approximately the same as the rate of change of each line of the turbine rotation speed Nt and the clutch rotation speed Nc, and in Figure 5, the lines are approximately parallel in slope.

As described above, when a gear shift is performed with the lock-up clutch 35 released, the control device for a vehicle drive device according to this embodiment determines the driving force (engine required torque Ter) at the completion of the gear shift, taking into account the accelerator pedal depression amount, vehicle speed, engine rotation speed Ne, and gear position, and calculates the turbine required torque Ttr to be input to the gear shift clutch 32. Then, the control device is configured to calculate the target clutch torque Tc* based on the turbine required torque Ttr, and control the clutch actuator 33 to engage the gear shift clutch 32 based on the target clutch torque Tc*.

With this configuration, the control device for the vehicle drive device according to this embodiment can match the turbine torque and clutch torque input to the shift clutch 32 when the shift is completed, even when the shift is performed with the lock-up clutch 35 not engaged.

This prevents the variable speed clutch 32 from suddenly engaging without slipping, which can cause shock due to the inertia of the engine 2. It also prevents the engine speed from revving up and shock from occurring.

Furthermore, since the above-mentioned shock and engine speed increase can be prevented when the shift is completed with the lock-up clutch 35 not engaged, smooth shifting can be achieved even when the lock-up clutch 35 is not engaged. This prevents the time required for shifting from becoming long and prevents sluggish acceleration.

In this way, the control device for a vehicle drive system according to this embodiment can smoothly engage the shift clutch 32 and perform smooth gear changes without impairing drivability, even when the lock-up clutch 35 is not engaged.

The control device for the vehicle drive device according to this embodiment is also configured to control the clutch actuator 33 to disengage and engage the shift clutch 32 during gear shifting, and to request a predetermined engine torque from the engine 2.

With this configuration, the control device for the vehicle drive device according to this embodiment can request a torque reduction or torque increase from the engine 2 by requesting a specified engine request torque that is different from the driver request engine torque calculated from the accelerator opening during gear shifting.

In addition, the control device for the vehicle drive device according to this embodiment calculates the target engine rotation speed Ne* based on the engine torque requirement Ter and the target turbine rotation speed Nt*, and is therefore able to calculate the speed ratio SR for determining the turbine torque requirement Ttr, which is the basis for calculating the target clutch torque Tc*.

In addition, the control device for the vehicle drive device in this embodiment calculates the turbine required torque Ttr based on the engine required torque Ter and the target engine rotation speed Ne*, and can therefore calculate the target clutch torque Tc* based on the turbine required torque Ttr.

Although an embodiment of the present invention has been disclosed, it is apparent that modifications may be made by one of ordinary skill in the art without departing from the scope of the present invention. All such modifications and equivalents are intended to be included in the following claims.

1 Vehicle 2 Engine 3 Automatic transmission (vehicle drive device)
4 Drive wheel 10 Control device 21 Crankshaft 30 Torque converter 31 Speed change mechanism 32 Speed change clutch 32a Clutch wheel disc 32b Clutch disc 33 Clutch actuator 35 Lock-up clutch 36 Turbine shaft 37 Input shaft 38 Output shaft 40 Hydraulic control device 50 Crank angle sensor 51 Turbine rotation speed sensor 52 Clutch rotation speed sensor 53 Clutch position detection sensor 54 Lock-up hydraulic sensor 55 Vehicle speed sensor 56 Accelerator sensor 101 Clutch control unit (control unit)
102 Lock-up clutch control unit Ter Engine required torque Ttr Turbine required torque Tc* Target clutch torque Ne* Target engine rotation speed Nt* Target turbine rotation speed

Claims (4)

a torque converter with a lock-up clutch connected to the engine;
a speed change mechanism that changes the rotation of the engine at a speed change ratio corresponding to a gear shift stage and outputs the changed rotation;
a variable speed clutch that is provided between the torque converter and the speed change mechanism and that can be switched between an engaged state in which power is transmitted and a disconnected state in which power is disconnected;
A clutch actuator that automatically operates the gear shift clutch;
A control device for a vehicle drive device comprising:
A control unit is provided for controlling the drive of the clutch actuator.
The control unit is a control device for a vehicle drive device, characterized in that, when a shift is performed to switch the gear stage while the lock-up clutch is released, the control unit calculates a target clutch torque based on a turbine required torque, which is a required value of the torque output from the torque converter, and controls the clutch actuator to engage the shift clutch based on the target clutch torque. 2. The control device for a vehicle drive device according to claim 1, wherein the control unit requests a predetermined engine required torque from the engine when a shift is performed to switch the gear position while the lock-up clutch is released . The control device for a vehicle drive device according to claim 2, characterized in that the control unit calculates the target engine rotation speed based on the predetermined engine torque requirement and a target turbine rotation speed, which is the target rotation speed of a turbine shaft connected to the torque converter and the variable speed clutch. The control device for a vehicle drive system according to claim 3, characterized in that the control unit calculates the turbine required torque based on the predetermined engine required torque and the target engine rotation speed.

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