Vehicle drive device control device

Abstract

To provide a vehicle drive system control device capable of achieving a smooth gear change through smoothly engaging a clutch without impairing drivability even when a lock-up clutch is not engaged.SOLUTION: A vehicle drive system control device comprises: a torque converter with a lock-up clutch connected to an engine; a transmission mechanism which outputs engine rotation by changing a rotation speed; a transmission clutch arranged between the torque converter and the transmission mechanism; and a clutch actuator which automatically performs a clutch operation. When a gear is changed with the lock-up clutch released, the clutch control section calculates target clutch torque Tc* on the basis of turbine demand torque Ttr which is a demand value of torque output from the torque converter and controls the clutch actuator so that the transmission clutch is engaged on the basis of the target clutch torque Tc*.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a control device for a vehicle drive device. [Background technology]

[0002] Patent Document 1 discloses a power transmission device that includes a fluid coupling that transmits engine power to the transmission side, a lock-up clutch for mechanically connecting and disconnecting the fluid coupling, and a speed change clutch that is provided between the fluid coupling and the transmission and that is connected and disconnected in response to a gear change operation of the transmission, and that connects the lock-up clutch before the speed change clutch when a peculiar starting operation is performed by the driver. The power transmission device described in Patent Document 1 can prevent poor connection of the lock-up clutch. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-76667 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the power transmission device described in Patent Document 1, the control related to the 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, during acceleration when starting from a standstill, acceleration may become sluggish, which may deteriorate drivability.

[0005] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a control device for a vehicle drive device that can smoothly engage the shift clutch and perform smooth gear changes without compromising drivability, even when the lock-up clutch is not engaged. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the present invention provides a control device for a vehicle drive device including a torque converter with a lock-up clutch connected to an engine, a transmission mechanism that changes the rotation of the engine at a gear ratio corresponding to the gear stage and outputs it, a transmission clutch that is provided between the torque converter and the transmission mechanism and can be switched to an engaged state to transmit power or a disconnected state to disconnect the power, and a clutch actuator that automatically operates the transmission clutch, the control device including 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 transmission is performed to switch the gear stage with the lock-up clutch released, and to control the clutch actuator to engage the transmission clutch based on the target clutch torque. Effect of the Invention

[0007] According to the present invention, a control device for a vehicle drive device can be provided that can smoothly engage the shift clutch to perform smooth gear changes without compromising drivability, even when the lock-up clutch is not engaged. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of a vehicle equipped with a control device for a vehicle drive device according to one embodiment of the present invention. [Diagram 2] 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. [Diagram 3] 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. [Figure 4] FIG. 4 is an example of a map referenced by the control device for a vehicle drive device according to one embodiment of the present invention, and is a characteristic map showing the relationship between the speed ratio and the torque ratio. [Diagram 5] FIG. 5 is an example of a timing chart showing transitions of the engine rotation speed, the turbine rotation speed, and the clutch rotation speed during gear shifting in a vehicle equipped with a control device for a vehicle drive device according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A control device for a vehicle drive device according to one embodiment of the present invention includes a torque converter with a lock-up clutch connected to an engine, a transmission mechanism that changes the rotation of the engine at a gear ratio corresponding to a gear position and outputs the changed speed clutch, a transmission clutch that is provided between the torque converter and the transmission mechanism and can be switched between an engaged state for transmitting power and a disconnected state for disconnecting the power, and a clutch actuator that automatically operates the transmission clutch, and includes a control unit that controls the drive of the clutch actuator, and the control unit is characterized in that when a shift is performed to switch the gear position with the lock-up clutch released, the control unit calculates a target clutch torque based on a turbine required torque that is a required value of the torque output from the torque converter, and controls the clutch actuator to engage the transmission 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 transmission clutch without impairing drivability even when the lock-up clutch is not engaged, thereby performing a smooth shift. EXAMPLES

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A vehicle equipped with a control device for a vehicle drive device according to an embodiment of the present invention will now be described with reference to the drawings.

[0011] As shown in FIG. 1, a 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.

[0012] The engine 2 is formed with a plurality of cylinders. In this embodiment, the engine 2 is configured to perform a series of four strokes, which are an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke, for each cylinder. The engine 2 is a power source for the vehicle 1.

[0013] The automatic transmission 3 is provided in a power transmission path between the engine 2 and 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.

[0014] 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 a power transmission path between the engine 2 and the variable speed clutch 32, and transmits power via a fluid to output the power to a turbine shaft 36.

[0015] A 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 a rotation difference through a fluid, and outputs the amplified torque 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.

[0016] 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.

[0017] The lock-up clutch 35 is provided within 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 integrally to transmit power, and a released state in which the direct connection between the crankshaft 21 and the turbine shaft 36 is released and the crankshaft 21 and the turbine shaft 36 transmit power via a fluid (hydraulic oil).

[0018] The lock-up clutch 35 is switched to the engaged state by supplying hydraulic pressure (hereinafter, this hydraulic pressure is referred to as "engagement hydraulic 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 pressure (hereinafter, this hydraulic pressure is referred to as "release hydraulic pressure") to the release chamber and discharging hydraulic oil from the apply chamber.

[0019] The transmission mechanism 31 is provided in a power transmission path between the transmission clutch 32 and the drive wheels 4, and has an input shaft 37 connected to the transmission clutch 32, and an output shaft 38 connected to the drive wheels 4 via a differential (not shown). The transmission mechanism 31 converts the driving force input from the transmission clutch 32 to the input shaft 37, changes the rotational speed, and outputs it from the output shaft 38.

[0020] The transmission mechanism 31 changes the rotation of the engine 2, which is output from the engine 2 and transmitted to an input shaft 37, at a gear ratio corresponding to one of a plurality of gears, which will be described later, selected, and outputs the changed rotation to an 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.

[0021] The transmission mechanism 31 is configured to be capable of forming a plurality of gear stages with different gear ratios by a plurality of 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 judges whether a gear shift is necessary by referring to a gear shift map based on the vehicle speed and the depression amount of the accelerator pedal, and outputs a gear shift command to the shift actuator. Then, the shift actuator that receives the gear shift command operates to perform the gear shift.

[0022] The variable speed clutch 32 is provided in a power transmission path between the torque converter 30 and the transmission mechanism 31. The variable speed clutch 32 has a clutch wheel disc 32a connected to the turbine shaft 36 so as to rotate integrally therewith, and a clutch disc 32b connected to the input shaft 37 of the transmission mechanism 31 so as to rotate integrally therewith.

[0023] 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 disconnect 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 disconnects the power transmission between the turbine shaft 36 and the input shaft 37 in the disconnected state.

[0024] The operation of switching the speed-change clutch 32 between an engaged state and a disengaged state (hereinafter referred to as “clutch operation”) is performed automatically by a clutch actuator 33.

[0025] The clutch actuator 33 is electrically connected to the control device 10, and performs clutch operation of the speed change clutch 32 based on a command from the control device 10. Specifically, the clutch actuator 33 moves a release bearing (neither of which is shown) in the axial direction of the input shaft 37 using a release fork or the like, and causes the release bearing to elastically deform a diaphragm spring of the clutch wheel disc 32a, thereby disengaging the speed change clutch 32. The clutch actuator 33 also moves the release bearing from the disengaged position in the opposite direction to that used for disengaging the clutch, thereby releasing the diaphragm spring from elastic deformation, thereby disengaging the speed change clutch 32.

[0026] The control device 10 is composed of a computer unit equipped with a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory for storing backup data, etc., an input port, and an output port.

[0027] The ROM of the computer unit stores various constants, various maps, and the like, as well as a program for causing the computer unit to function as the control device 10. That is, the CPU executes the program stored in the ROM using the RAM as a working area, whereby the computer unit functions as the control device 10 in this embodiment.

[0028] The control device 10 is connected to various devices such as the shift actuator, clutch actuator 33, and hydraulic control device 40 described above (not shown), as well as 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.

[0029] 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 released 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 variable speed clutch 32 between an engaged state and a released state by adjusting the magnitude of the hydraulic pressure supplied to the clutch actuator 33 based on a command from the control device 10.

[0030] The crank angle sensor 50 detects the rotation angle (hereinafter referred to as the "crank angle") of the crankshaft 21. 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.

[0031] The turbine rotation speed sensor 51 detects the rotation speed (hereinafter referred to as "turbine rotation speed") of the turbine shaft 36. The clutch rotation speed sensor 52 detects the rotation speed (hereinafter referred to as "clutch rotation speed") of the clutch disc 32b and the input shaft 37.

[0032] The clutch position detection sensor 53 detects the position of the release bearing in the speed change clutch 32 or the position of a part such as a release fork that moves in relation to the moving state of the release bearing (hereinafter referred to as the "clutch position"). The clutch position indicates the state of the speed change clutch 32 (disengaged state / half-clutch state / engaged state), and can also be considered to indicate the magnitude of the torque transmitted by the speed change 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 is shown in which the engaging oil pressure acting on the apply chamber is detected, 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 a throttle valve that changes in conjunction with the amount of depression of the accelerator pedal.

[0033] 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 as to perform the clutch operation of the shift clutch 32. The clutch control unit 101 in this embodiment constitutes a control unit.

[0034] When changing gears, the control device 10 automatically performs clutch operation and shift operation by controlling the clutch actuator 33 and the shift actuator so as to switch the gear change clutch 32 from an engaged state to a disengaged state, then switch the gear in the transmission mechanism 31, and then switch the gear change clutch 32 from a disengaged state to an engaged state.

[0035] In order to perform the above-mentioned gear shift smoothly and without any discomfort (without impairing drivability), it is desirable that the torque input to gear shift clutch 32 and the clutch torque match when the gear shift is completed.

[0036] If the torque input to the transmission clutch 32 is greater than the clutch torque, the transmission clutch 32 will slip and the engine speed will increase. Conversely, if the torque input to the transmission clutch 32 is less than the clutch torque, the transmission clutch 32 will suddenly engage without slipping, causing the engine to stall due to a sudden drop in engine speed, or a shock to the vehicle body due to the action of the inertia (inertia force) on the engine 2 side.

[0037] Therefore, when engaging the variable speed clutch 32 in conjunction with a gear shift, it is preferable that the control device 10 sets a clutch torque corresponding to the torque input to the variable speed clutch 32 as a target clutch torque and controls the engagement of the variable speed clutch 32.

[0038] Here, when the lock-up clutch 35 is engaged, the crankshaft 21 and the turbine shaft 36 are directly connected, so the above-mentioned "torque input to the shift clutch 32" is engine torque. Therefore, when shifting is performed with the lock-up clutch 35 engaged, the control device 10 may set the target clutch torque based on the engine required torque, which is the torque required of the engine 2.

[0039] 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 that 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 is performed with the lock-up clutch 35 released, the torque input to the shift clutch 32 and the clutch torque will not match when the shift is completed. In this case, the engine speed may rev up or a shock may occur as described above, which may impair drivability.

[0040] 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.

[0041] The control device 10 has a function as a lock-up clutch control unit 102 that controls the engagement or release of the lock-up clutch 35. For example, when a predetermined lock-up condition is established, the control device 10 executes lock-up control that controls the hydraulic control device 40 so as to switch the lock-up clutch 35 from a released state to an engaged state.

[0042] In this embodiment, the predetermined lock-up condition is, for example, when the vehicle speed is equal to or greater than a predetermined vehicle speed. The predetermined lock-up condition is not limited to this, and may be other conditions, or the state of the gear position and the vehicle speed may be the predetermined lock-up condition.

[0043] (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.

[0044] In explaining the method of calculating the target clutch torque, 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 target values ​​of parameters not marked with "*", and parameters marked with "r" indicate required values ​​of parameters not marked with "r".

[0045] Ne: Engine speed Ne*: Target engine speed Nt: Turbine rotation speed Nt*: Target turbine rotation speed Nc: Clutch rotation speed Te: Engine torque Ter: Engine torque requirement 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: Imperial Architect It: Turbine inertia Ic: Clutch inertia

[0046] Moreover, other parameters not explicitly shown in FIG. 2 are defined as follows. SR: Speed ​​ratio τ: Torque ratio dωe / dt: Engine speed change (dωt / dt)*: Target turbine rotation change amount dωc / dt: Clutch rotation change amount

[0047] 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.

[0048] In addition, when 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 RPM change amount ≒ Turbine RPM change amount = Clutch RPM change amount

[0049] When the shift is completed, the turbine rotation speed and the clutch rotation speed are synchronized with each other due to the engagement of the shift clutch 32, so the precondition (1) above must be satisfied.

[0050] During the shift, the 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 shift is completed, the engine requested torque is made to match or approach the driver requested engine torque to prevent a torque step from occurring when the shift is completed, so that the engine requested torque matches the driver requested engine torque. For this reason, the above precondition (2) must be satisfied when the shift is completed.

[0051] 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, although the engine rotation change amount does not exactly match the turbine rotation change amount because it passes through the torque converter 30, the difference in the rotation speed of the torque converter 30 becomes stable at the completion of the shift, so the engine rotation change amount is treated as having 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 approximately the same as the slope (speed of change) of each line of the turbine rotation speed Nt and the clutch rotation speed Nc.

[0052] 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 shifting (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, and the driver's intention to accelerate, including whether it is fast or slow, is determined, and the driving force (target clutch torque Tc*) required at the completion of the shifting is calculated from the vehicle speed detected by the vehicle speed sensor 55, the engine rotation speed Ne, and the gear position. As shown in FIG. 3, the control device 10 calculates the inertia torque "(dωe / dt)×(Ii+Ie)" from the engine rotation change amount dωe / dt, the impeller inertia Ii, and the engine inertia Ie (step S1). Specifically, the control device 10 calculates the inertia torque "(dωe / dt)×(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 is equivalent to the clutch rotation change amount according to the above preconditions, and the current value is used. The impeller shaving Ii and the engine inertia Ie are design values ​​or values ​​obtained experimentally.

[0053] The control device 10 calculates the impeller required torque Tir by subtracting the inertia torque "(dωe / dt)×(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.

[0054] 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 in which the relationship between the target turbine speed, the impeller required torque, and the target engine speed is calculated in advance. The conversion map is stored in the ROM of the control device 10. The target turbine speed Nt* here is a target value of the turbine speed Nt at the completion of the shift, and according to the above premise, is the same value as the clutch speed Nc at the completion of the shift. The target turbine speed Nt* is calculated based on the vehicle speed at the completion of the shift, for example.

[0055] The conversion map is a map calculated based on characteristic data (capacity coefficient, torque ratio) of the torque converter 30. The conversion map is a map of the input rotation speed (engine rotation speed Ne) of the torque converter at the equilibrium point where the theoretical input torque of the torque converter 30 is balanced with the input torque (impeller torque Ti) determined in advance and the turbine rotation speed (Nt*) determined in advance.

[0056] The theoretical input torque is calculated by multiplying the capacity coefficient by the square of the input rotation speed. Because the capacity coefficient changes based on the speed ratio, it is necessary to continuously change the input rotation speed of the torque converter to calculate the equilibrium point when calculating the conversion map.

[0057] 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.

[0058] Therefore, by referring to a conversion map which maps the theoretical input torque of the torque converter 30 and the torque converter input speed (engine rotation speed Ne) at the balance point between the theoretical input torque and the input torque of the torque converter 30, for a predetermined input torque (impeller torque Ti) and a predetermined turbine rotation speed (Nt*), the target engine rotation speed Ne* at the balance point can be calculated from the target turbine rotation speed Nt* and the impeller required torque Tir calculated in step S2 (step S3).

[0059] 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.

[0060] 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).

[0061] The torque converter characteristic is a characteristic that is determined based on specifications such as the transmission torque capacity of the torque converter 30. 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 a 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.

[0062] In this embodiment, by using the characteristic map shown in Fig. 4, the impeller torque can be converted into turbine torque as described later, regardless of the impeller torque, engine rotation speed, etc. Therefore, 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.

[0063] 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 a required value of the torque output from the torque converter 30 and input to the variable speed clutch 32, and is a required value of the turbine torque Tt at the time of completion of the shift (at the time of completion of engagement of the variable speed clutch 32).

[0064] The control device 10 calculates the target turbine rotation change amount (dωt / dt)* by differentiating the target turbine rotation speed Nt* with respect to time (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.

[0065] 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 a 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.

[0066] Next, with reference to FIG. 5, a description will be given of transitions in the engine rotation speed, the turbine rotation speed, and the clutch rotation speed when a gear shift is performed in the vehicle 1 of this embodiment with the lock-up clutch 35 not engaged.

[0067] As shown in Fig. 5, at time t0, the vehicle 1 is accelerating at a predetermined gear. While the vehicle 1 is accelerating at the predetermined gear, the variable speed clutch 32 is engaged, so the turbine rotation speed Nt and the clutch rotation speed Nc are synchronized and increase with each other. 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.

[0068] After that, at time t1, the gear shift control is executed and a gear shift (upshift) from a predetermined gear to a higher gear is started. That is, when the gear shift control is started, the gear 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 is suddenly reduced by the operation of a synchronizing device (not shown) to adjust the rotation speed to a value corresponding to the vehicle speed. Note that, when the gear shift control is executed as described above, the engine torque is suppressed by a torque reduction request. Therefore, the engine rotation speed Ne is gradually reduced.

[0069] Then, at time t2, when the shifting of the gear stage in the transmission mechanism 31 is completed, the clutch rotation speed Nc becomes a rotation speed corresponding to the vehicle speed and the gear stage after the upshift. Also, since the transmission clutch 32 is in a disengaged state and the load applied to 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 in the 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 driving wheels 4, the vehicle speed gradually increases, and the clutch rotation speed Nc also gradually increases.

[0070] Furthermore, 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 a rotation difference occurs between the engine rotation speed Ne and the turbine rotation speed Nt because of acceleration.

[0071] Then, at time t3, when the shift is completed, the variable speed 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 power transmission via fluid in the torque converter 30, and becomes a rotation speed higher than these turbine rotation speed Nt and clutch rotation speed Nc. 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 is a line with an approximately parallel inclination in FIG. 5.

[0072] As described above, when a gear shift is performed with 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 in consideration of the accelerator pedal depression amount, vehicle speed, engine rotation speed Ne, and gear position, and calculates turbine required torque Ttr to be input to gear shift clutch 32. Then, the control device is configured to calculate target clutch torque Tc* based on turbine required torque Ttr, and control clutch actuator 33 to engage gear shift clutch 32 based on the target clutch torque Tc*.

[0073] With this configuration, the control device for a vehicle drive device in this embodiment can match the turbine torque and clutch torque input to the shift clutch 32 at the time the shift is completed, even when the shift is performed with the lock-up clutch 35 not engaged.

[0074] This makes it possible to prevent the variable speed clutch 32 from suddenly engaging without slipping, which would cause a shock due to the action of inertia (inertial force) on the engine 2 side. It is also possible to prevent the engine rotation speed from increasing and the occurrence of a shock.

[0075] Furthermore, since it is possible to prevent the above-mentioned shock and increase in engine speed when the gear shift is completed with the lock-up clutch 35 not engaged, it is possible to perform a smooth gear shift even with the lock-up clutch 35 not engaged. This makes it possible to prevent the time required for gear shifting from becoming long and to prevent sluggish acceleration from occurring.

[0076] In this way, the control device for a vehicle drive device in this embodiment can smoothly engage the shift clutch 32 and perform smooth gear changes without compromising drivability, even when the lock-up clutch 35 is not engaged.

[0077] In addition, the control device for a vehicle drive device in this embodiment is configured to control the clutch actuator 33 to disengage and engage the variable speed clutch 32 during gear shifting, and to request a predetermined engine required torque from the engine 2.

[0078] With this configuration, the control device of the vehicle drive device of this embodiment can request a torque reduction or torque increase from the engine 2 by requesting a predetermined engine request torque different from the driver request engine torque calculated from the accelerator opening degree during gear shifting.

[0079] In addition, the control device for a vehicle drive device according to this embodiment calculates the target engine rotation speed Ne* based on the engine required torque Ter and the target turbine rotation speed Nt*, and therefore can calculate the speed ratio SR for determining the turbine required torque Ttr, which is the calculation basis for the target clutch torque Tc*.

[0080] In addition, the control device for a vehicle drive device according to this embodiment calculates the turbine required torque Ttr based on the engine required torque Ter and the target engine rotation speed Ne*, and is therefore able to calculate the target clutch torque Tc* based on the turbine required torque Ttr.

[0081] Although an embodiment of the invention has been disclosed, it will be apparent to one of ordinary skill in the art that modifications may be made therein without departing from the spirit and scope of the invention, and it is intended that all such modifications and equivalents be included in the following claims. [Explanation of symbols]

[0082] 1 vehicle 2 Engine 3 Automatic transmission (vehicle drive system) 4 Drive wheels 10 Control device 21 Crankshaft 30 Torque converter 31 Transmission mechanism 32 Shift 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 Lockup oil pressure sensor 55 Vehicle speed sensor 56 Accelerator Sensor 101 Clutch control unit (control unit) 102 Lock-up clutch control unit Ter Engine torque requirement Ttr Turbine required torque Tc* Target clutch torque Ne* Target engine speed Nt* Target turbine speed

Claims

1. 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 ratio corresponding to a gear position 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 speed change clutch; A control device for a vehicle drive device comprising: A control unit is provided for controlling the driving 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. 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.

3. 3. The control device for a vehicle drive device according to claim 2, wherein the control unit calculates a target engine rotation speed based on the predetermined engine required torque and a target turbine rotation speed that is a target rotation speed of a turbine shaft connected to the torque converter and the variable speed clutch.

4. 4. The control device for a vehicle drive device according to claim 3, wherein 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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