Vehicle control system

Abstract

To enable a connection / disconnection device to be engaged without restricting power source torque while suppressing the occurrence of judder and engagement shock.SOLUTION: A vehicle control device obtains a control gain G on the basis of a data map predetermined with a power source torque estimation value Tdest and differential rotation ΔN as variables, and controls lockup differential pressure Plu which is engagement transition pressure in accordance with a multiplication value Tdset×G obtained by multiplying the control gain G by the power source torque estimation value Tdest. In the data map of the control gain G, the control gain G is designed to increase as both the differential rotation ΔN and the power source torque estimation value Tdest increase. Because the lockup differential pressure Plu increases as the control gain G increases, the vehicle control device enables a lockup clutch (connection / disconnection device) to be engaged without restricting power source torque Td while suppressing the occurrence of judder and engagement shock even when the power source torque Td is increased by depressing operation of an accelerator pedal.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a control device for a vehicle, and particularly to a technique for controlling the engagement transition pressure of a connection / disconnection device that connects and disconnects a power transmission path between a power source and drive wheels.

Background Art

[0002] (a) A vehicle having a power source including an engine and a friction engagement type connection / disconnection device that connects and disconnects a power transmission path between the power source and drive wheels, and (b) a vehicle control device provided with an engagement control unit that controls the engagement transition pressure of the connection / disconnection device when engaging the connection / disconnection device, is known. The device described in Patent Document 1 is an example thereof. A clutch C1 that establishes the first gear stage of an automatic transmission provided in the power transmission path is used as the connection / disconnection device, and it is released when predetermined neutral control execution conditions are satisfied, while it is engaged when predetermined return conditions are satisfied. In order to suppress the occurrence of judder and engagement shock during the engagement, the power source torque (engine torque) is restricted so that the differential rotation of the connection / disconnection device (clutch C1) becomes the target differential rotation, and when the target differential rotation is reached, the hydraulic pressure (engagement transition pressure) and the power source torque are controlled so as to obtain the target hydraulic pressure gradient.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, since the power source torque is restricted according to the differential rotation and the target hydraulic pressure gradient, there is a possibility that the rise of the power source torque becomes slow and the drivability such as the driving force responsiveness is impaired.

[0005] The present invention was made against the above circumstances, and its objective is to engage the disconnection device while suppressing the occurrence of judder and engagement shock without limiting the power source torque. [Means for solving the problem]

[0006] The first invention relates to a vehicle having (a) a power source including an engine and a friction engagement type disconnection device for connecting and disconnecting a power transmission path between the power source and the drive wheels, and (b) a control device for a vehicle that includes an engagement control unit for controlling the engagement transient pressure of the disconnection device when engaging the disconnection device, and (c) the engagement control unit determines a control gain based on a predetermined relationship with an estimated value of the power source torque, which is the torque of the power source, and the differential rotation of the disconnection device as variables, and sets the control gain to the power source torque Estimated value (d) The engagement transient pressure is controlled according to the multiplicative value obtained by multiplying by the following: (e) The vehicle is equipped with a torque converter and an automatic transmission in series from the power source side in the power transmission path between the power source and the drive wheels, and the torque converter is provided with a lock-up clutch, and the lock-up clutch is the engagement and disengagement device; (f) The engagement control unit calculates the required torque capacity Tlu according to the following equation (1) using the inertia Ilu of the lock-up clutch, the target angular acceleration α, the estimated value Tdest of the power source torque, and the control gain G, and calculates the target value Plut of the lock-up differential pressure corresponding to the engagement transient pressure according to the following equation (2) using the required torque capacity Tlu, the hydraulic conversion coefficient K, and the friction coefficient μ, and controls the engagement of the lock-up clutch with the target value Plut. Tlu=Tdest×G-Ilu×α...(1) Plut = Tlu / K / μ ···(2) The above control gain corresponds to a correction coefficient used when engaging the disconnection device according to the estimated torque value of the power source. For example, it can be set to a value that straddles 1.0, but it is also possible to set the control gain within a range of 1.0 or more, or 1.0 or less.

[0007] The second invention is a vehicle control device according to the first invention, characterized in that (a) a neutral control unit opens the disconnection device to interrupt the power transmission path when predetermined neutral control execution conditions are met, and engages the disconnection device when predetermined return conditions are met, and (b) when the neutral control unit engages the disconnection device after the return conditions are met, the engagement transient pressure of the disconnection device is controlled by the engagement control unit. [Effects of the Invention]

[0010] In such vehicle control systems, a control gain is determined based on a predetermined relationship between the estimated power source torque and the differential rotation of the disconnection device, and the engagement transient pressure is controlled according to the multiplier obtained by multiplying the estimated power source torque by this control gain. In this case, the predetermined relationship is set such that the control gain increases as the differential rotation increases, and the control gain increases as the estimated power source torque increases. As the engagement transient pressure increases with increasing control gain, the disconnection device can be engaged while suppressing the occurrence of judder and engagement shock without limiting the power source torque, even when the power source torque increases due to operations such as pressing the accelerator pedal.

[0011] In other words, when engaging the disconnection device, if the power source torque increases due to an operation such as pressing the accelerator pedal, the control gain changes as shown, for example, at points a → b → c in Figure 3. The three-dimensional surface shown by the square mesh in Figure 3 is an example of a predetermined relationship between the control gain G, the estimated power source torque (estimated value of power source torque) Tdest, and the differential rotation ΔN, and the control gain G can be moved on the surface of this three-dimensional surface from point a to point b and point c. To explain in more detail, at the beginning of engagement control, the differential rotation ΔN is large, and there is a response delay in the rise of power source torque including the engine, so the control gain G is relatively large (point a), and the differential rotation ΔN is rapidly reduced based on the large engagement transient pressure. As the differential rotation ΔN decreases, the control gain G decreases (point b), so the engagement transient pressure is kept low relative to the estimated power source torque Tdest, the slip engagement state of the disconnection device is maintained, and the engagement shock due to sudden engagement is suppressed. In this state, when the estimated power source torque Tdest increases, the control gain G increases accordingly (point c), so the disconnection device is quickly engaged with a relatively large engagement transient pressure, suppressing power source torque surges and judder.

[0012] On the other hand, since the control gain is determined using the differential rotation of the disconnection device as a variable, the engagement transient pressure of the disconnection device can be appropriately controlled and engaged based on the actual differential rotation, regardless of calculation errors in the estimated power source torque, control errors in the engagement transient pressure, response delays, etc. In other words, when controlling the engagement transient pressure based on the estimated power source torque, the control may become unstable due to the effects of such calculation errors and control errors. However, by detecting the actual differential rotation of the disconnection device and controlling the engagement transient pressure in a feedback manner, the effects of calculation errors and control errors are reduced, and stable engagement control of the disconnection device can be achieved. During the engagement transient of the disconnection device, the friction characteristics change depending on whether it is static or dynamic friction. However, since the control gain is determined using the differential rotation as a variable, the change in friction characteristics can also be absorbed by the control gain. The first invention is particularly effective when a lock-up clutch provided in a torque converter is used as a disconnection device. In particular, while the control of the lock-up clutch's engagement transient pressure is affected by torque transmission by the torque converter with respect to the input torque, the control gain is determined using the differential rotation of the lock-up clutch as a variable. This makes it possible to absorb the effect of torque transmission by the torque converter, thus facilitating the engagement control of the lock-up clutch.

[0013] The second invention relates to neutral control, and the effect of the present invention can be appropriately obtained, not only when the accelerator pedal is pressed as a return condition, but also when the accelerator pedal is pressed during the return even if it is not a return condition, as the disconnection device can be engaged while suppressing the occurrence of judder and engagement shock without limiting the power source torque. [Brief explanation of the drawing]

[0015] [Figure 1] This is a schematic diagram of a vehicle equipped with an electronic control device as a control device to which the present invention is applied. [Figure 2] Figure 1 is a flowchart illustrating the operation of the neutral control unit, which is functionally equipped in the electronic control unit, during the return control process. [Figure 3] This figure illustrates an example of a data map used in step S4 of the flowchart in Figure 2 when determining the control gain G using the differential rotation ΔN of the lock-up clutch and the estimated power source torque Tdest as variables. [Figure 4] This is an example of a time chart illustrating the changes in the operating state of each part when the lock-up clutch is engaged according to the flowchart in Figure 2 during the return to neutral control. [Modes for carrying out the invention]

[0016] The present invention is preferably applied to vehicles in which a torque converter and an automatic transmission are provided in series from the power source side in the power transmission path between the power source, including the engine, and the drive wheels, and the torque converter is provided with a lock-up clutch, which is used as a disconnection device. However, it can be applied to various vehicles that have at least a power source including the engine and a disconnection device. The engine is an internal combustion engine such as a gasoline engine or a diesel engine. The power source may be the engine alone, or it may be equipped with other power sources such as an electric motor in addition to the engine. The estimated value of the power source torque is calculated, for example, from the amount of intake air and rotational speed of the engine, but it may also be calculated using target values ​​and command values ​​of various control elements related to the power source torque.

[0017] As friction-engagement type disconnecting devices, in addition to the lock-up clutch mentioned above, hydraulic clutches and brakes provided in automatic transmissions and forward / reverse switching devices that can form multiple gear stages with different gear ratios are preferably used. A starting clutch or the like, which is provided separately from the automatic transmission, can also be used as a disconnecting device. The engagement transient pressure of the disconnecting device is the engagement pressure during slip engagement when the disconnecting device is frictionally engaged and has a transmission torque capacity.

[0018] Conditions for executing neutral control include, for example, the accelerator being OFF (accelerator not pressed), the brake being ON (brake pedal pressed), the shift range being a non-driving range such as N, the vehicle being driven, and the vehicle being stopped. Conditions for returning to neutral control include, for example, the brake being OFF (brake pedal not pressed), the shift range being a driving range such as D, and the accelerator being ON (accelerator pedal pressed). Neutral control is a control that opens the disconnection device to interrupt the power transmission path. This can be done in parallel with engine shutdown by fuel cut, but it is also sufficient to simply interrupt the power transmission path while the engine is running. [Examples]

[0019] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Figure 1 is a schematic diagram of a vehicle 10 equipped with an electronic control device 70 as a control device to which the present invention is applied, and also shows the main parts of the control system. The vehicle 10 is equipped with an engine 12 as a power source for driving, and the output of the engine 12 is transmitted to the left and right drive wheels 20 via a power transmission path including a torque converter (T / C) 14, an automatic transmission 16, and a differential gear 18. The engine 12 is an internal combustion engine such as a gasoline engine that generates power by the combustion of fuel, and is equipped with a fuel injection device 22 that controls the amount of fuel injected, an electronic throttle valve 24 that controls the amount of intake air Q, and an ignition timing control device 26 that controls the ignition timing. The fuel injection device 22 controls the amount of fuel injected according to a fuel injection control signal Se1 supplied from the electronic control device 70. The electronic throttle valve 24 controls the throttle valve opening θth according to a throttle control signal Se2 supplied from the electronic control device 70, and the amount of intake air Q is controlled according to this throttle valve opening θth. The ignition timing control device 26 controls the ignition timing of an igniter (not shown) according to the ignition timing control signal Se3 supplied from the electronic control device 70.

[0020] The torque converter 14 includes a pump impeller connected to the crankshaft of the engine 12, a turbine impeller connected to the input shaft of the automatic transmission 16, and a stator, and performs power transmission between the pump impeller and the turbine impeller via a fluid, and also includes a lock-up (L / U) clutch 30 that directly connects the pump impeller and the turbine impeller. The lock-up clutch 30 is a hydraulic friction clutch that is frictionally engaged according to the lock-up differential pressure Plu, which is the hydraulic pressure difference between the hydraulic pressure in the engagement-side oil chamber and the hydraulic pressure in the release-side oil chamber. When it is completely engaged so as to be non-rotatable relative to each other, the torque converter 14 enters a lock-up state in which the rotation of the engine 12 is directly transmitted to the automatic transmission 16. When the lock-up differential pressure Plu is controlled so that the hydraulic pressure in the release-side oil chamber becomes high, an open state is established in which relative rotation of the pump impeller and the turbine impeller is permitted, and the torque converter 14 enters a torque converter state in which power transmission is performed solely via the fluid. Further, when the lock-up differential pressure Plu is feedback-controlled so that the lock-up clutch 30 is rotated at a predetermined slip amount, the torque converter 14 enters a flex control state in which the turbine impeller and the pump impeller are relatively rotated by the same differential rotation as the slip amount of the lock-up clutch 30. The slip amount of the lock-up clutch 30 can be represented by the differential rotation ΔN (=Ne - Nt) between the engine rotation speed Ne and the turbine rotation speed Nt.

[0021] The lock-up differential pressure Plu is regulated by controlling an electromagnetic pressure regulating valve, an electromagnetic switching valve, etc. of the hydraulic pressure control circuit 32 according to the lock-up control signal Slu output from the electronic control device 70, and the lock-up clutch 30 is switched to any one of a fully engaged state, a slip engaged state, and an open state. The fully engaged state and the slip engaged state of the lock-up clutch 30 are connection states in which the lock-up clutch 30 transmits power with a predetermined transmission torque capacity, and the open state of the lock-up clutch 30 is a cut-off state in which its transmission torque capacity becomes 0 and power transmission is interrupted. The torque converter 14 is a fluid transmission device, and the lock-up clutch 30 is a friction engagement type connection / disconnection device that connects and disconnects the power transmission path.

[0022] The automatic transmission 16 is a planetary gear type stepped transmission that can establish a plurality of gear stages with different gear ratios, and includes a plurality of clutches and brakes as hydraulic friction engagement devices. The plurality of clutches and brakes are switched by the manual valve of the hydraulic control circuit 32 according to the selection range Sra such as PRND selected by a range selection operation device 50 such as a shift lever, and the electromagnetic pressure regulating valve, electromagnetic switching valve, etc. of the hydraulic control circuit 32 are controlled according to the shift control signal Sat output from the electronic control device 70, whereby the engaged / disengaged state is switched. As the automatic transmission 16, a belt type continuously variable transmission may be used, or a compound transmission in which a belt type continuously variable transmission and a gear type transmission device are provided in parallel may be used, and various modes are possible.

[0023] The vehicle 10 includes an electronic control device 70 as a control device for controlling the engine 12, the automatic transmission 16, etc. The electronic control device 70 is configured to include a so-called microcomputer including a CPU, a RAM, a ROM, an input / output interface, etc., and the CPU performs signal processing according to a program stored in the ROM in advance while using the temporary storage function of the RAM, thereby executing output control of the engine 12, shift control of the automatic transmission 16, engagement / disengagement control of the lock-up clutch 30, etc.

[0024] The electronic control unit 70 is supplied with signals representing various information necessary for control, such as the selected range Sra selected from multiple shift ranges by a range selection operating device 50 such as a shift lever, the accelerator opening Acc which is the amount operated on the accelerator pedal 54, the intake air amount Q of the engine 12, the engine rotation speed Ne which is the rotation speed of the engine 12, the turbine rotation speed Nt which is the output rotation speed of the torque converter 14, the vehicle speed V, and the brake ON signal Bon which is a signal indicating that the brake pedal for activating the wheel brakes is being operated by the driver. These signals are supplied from, for example, a selection range sensor 52, an accelerator opening sensor 56, an intake air amount sensor 58, an engine rotation speed sensor 62, a turbine rotation speed sensor 64, a vehicle speed sensor 66, a brake switch 68, etc. Multiple shift ranges switch the power transmission state of the automatic transmission 16. For example, there is a D range that allows forward driving according to the accelerator pedal position Acc, an R range that allows reverse driving according to the accelerator pedal position Acc, an N range that shuts off power transmission from the automatic transmission 16, and a P range for parking. One of these shift ranges is selected as the selected range Sra. The accelerator pedal position Acc corresponds to the driver's power output request.

[0025] The electronic control unit 70 functionally includes an engine control unit 72, a transmission control unit 74, and a lock-up clutch (L / U clutch) control unit 76. It outputs engine control signals for controlling the operation of the engine 12, including a fuel injection control signal Se1, a throttle control signal Se2, and an ignition timing control signal Se3. It also outputs a transmission control signal Sat for hydraulic control related to the shifting of the automatic transmission 16, and a lock-up control signal Slu for switching the engagement and disengagement states of the lock-up clutch 30. The electronic control unit 70 is configured to include separate electronic control units for engine control, transmission control, and lock-up clutch control as needed.

[0026] The engine control unit 72 controls the engine torque Te, which is the output of the engine 12, by outputting a fuel injection control signal Se1, a throttle control signal Se2, and an ignition timing control signal Se3 based on, for example, the accelerator opening Acc and the vehicle speed V.

[0027] The gear shift control unit 74 makes a gear shift decision according to a predetermined gear shift map (gear shift condition) using vehicle conditions such as vehicle speed V and accelerator opening Acc as parameters, and automatically switches the gears of the automatic transmission 16 by outputting a gear shift control signal Sat as needed. Specifically, the multiple forward gears are shifted to the lower-speed gear with a larger gear ratio as the vehicle speed V decreases, and even during coasting deceleration with the accelerator OFF and accelerator opening Acc approximately 0, the gears are shifted sequentially from the higher-speed gears to the lower-speed gears as the vehicle speed V decreases, while the gears are shifted to the lower-speed gear with a larger gear ratio as the accelerator opening Acc increases.

[0028] The lock-up clutch control unit 76 controls the operating state of the lock-up clutch 30. By controlling the lock-up differential pressure Plu according to the lock-up control signal Slu, it switches the lock-up clutch 30 to one of three states: fully engaged, slip engaged, or open. For example, using vehicle conditions such as vehicle speed V and throttle valve opening θth as parameters, it uses a predetermined relationship (lock-up region diagram) which has a fully engaged lock-up region, a slip engaged region, and a lock-up off region, to determine which region the actual vehicle speed V and throttle valve opening θth are in. Then, it outputs a lock-up control signal Slu to the hydraulic control circuit 32 to control the lock-up differential pressure Plu so that the lock-up clutch 30 enters the operating state corresponding to the determined region. That is, it is fully engaged in the fully engaged lock-up region, slip engaged in the slip engaged region, and open in the lock-up off region.

[0029] The lock-up clutch control unit 76 functionally includes a neutral control unit 78, and when certain neutral control execution conditions are met during operation in D range, it performs neutral control (N control) to release the lock-up clutch 30 and cut off the power transmission path. The neutral control execution conditions are defined, for example, to include accelerator OFF with accelerator opening Acc = 0, and the lock-up clutch 30 is released. The engine 12 continues to operate, for example in an idle state, but may be stopped by fuel cut under certain conditions. On the other hand, when predetermined return conditions are met, including accelerator ON with accelerator opening Acc = 1 or more of a predetermined value, return control is performed according to steps S1 to S8 (hereinafter, the steps are omitted and simply referred to as S1 to S8) of the flowchart in Figure 2, and the lock-up clutch 30 is engaged. In the flowchart in Figure 2, YES in the diamond-shaped decision steps means affirmation, and NO means negation. In this embodiment, the part of the series of controls by the neutral control unit 78 that performs return control, i.e., engagement control of the lock-up clutch 30, according to the flowchart in Figure 2 corresponds to the engagement control unit.

[0030] In S1 of Figure 2, it is determined whether the return condition for neutral control has been met, and if the return condition has been met, the engagement control from S2 onwards is executed. In S2, the differential rotation ΔN of the lock-up clutch 30 is detected. Specifically, the differential rotation ΔN is calculated by subtracting the turbine rotation speed Nt from the engine rotation speed Ne. In S3, the estimated power source torque Tdest is calculated. In this embodiment, since only the engine 12 is provided as the power source, the estimated power source torque Tdest is calculated from the engine rotation speed Ne, intake air volume Q, ignition timing, etc., to estimate the engine torque Te. In S4, the control gain G is calculated from a predetermined data map using the differential rotation ΔN and the estimated power source torque Tdest as variables. Figure 3 is an example of a data map for determining the control gain G, and it is set so that the larger the differential rotation ΔN, the larger the control gain G, and the larger the estimated power source torque Tdest, the larger the control gain G. In Figure 3, the three-dimensional surface shown as a grid of rectangles is an example of a predetermined relationship between the control gain G, the estimated power source torque Tdest, and the differential rotation ΔN. As the estimated power source torque Tdest and the differential rotation ΔN change, the control gain G is moved along this three-dimensional surface, for example, as shown by points a → b → c. The control gain G corresponds to the correction coefficient used when engaging the lock-up clutch 30 according to the estimated power source torque Tdest, and is set to straddle 1.0, for example. In the time chart of Figure 4, the dashed line in the column for the estimated power source torque Tdest represents the multiplied value Tdest × G, which is obtained by multiplying the estimated power source torque Tdest by the control gain G. The portion higher than the solid line, which represents the estimated power source torque Tdest, means that the control gain G is greater than 1.0, and the portion lower than the estimated power source torque Tdest means that the control gain G is less than 1.0.

[0031] In the following S5, the required torque capacity Tlu is calculated according to formula (1) using the inertia Ilu of the lock-up clutch 30, the target angular acceleration α, the estimated power source torque Tdest, and the control gain G. Although the inertia Ilu and target angular acceleration α are predetermined to be constant values, the target angular acceleration α may be set to be variable according to the accelerator opening Acc, etc. In the following S6, the target value Plut of the lock-up differential pressure Plu is calculated according to formula (2) using the required torque capacity Tlu, the hydraulic conversion coefficient K, and the friction coefficient μ, and the lock-up clutch 30 is engaged and controlled according to that target value Plut. The hydraulic conversion coefficient K is the pressure-receiving area of ​​the lock-up clutch 30. increase Depending increasing A predetermined value is set ru. The friction coefficient μ is predetermined to a fixed value depending on the type of friction material of the lock-up clutch 30. The lock-up differential pressure Plu is the engagement pressure of the lock-up clutch 30, i.e., the engagement pressure of the disconnection device. However, when controlling the engagement of the lock-up clutch 30 according to the flowchart in Figure 2, the lock-up differential pressure Plu during slip engagement corresponds to the engagement transient pressure.

[0032] In the next step, S7, an engagement check is performed to determine whether the differential rotation ΔN is approximately 0, indicating a fully engaged state. Steps S2 and below are repeated until the engagement check is successful. The engagement check is performed, for example, by determining whether the absolute value of the differential rotation ΔN remains approximately 0 (below a predetermined value) for a predetermined time or longer. If the engagement check in S7 is successful, the control termination process in S8 is executed. In the control termination process in S8, for example, the lock-up differential pressure Plu is increased to the maximum pressure such as the line pressure to maintain the lock-up clutch 30 in a fully engaged state.

[0033] Figure 4 is an example of a time chart showing the changes in the operating state of each part when the accelerator pedal 54 is pressed during acceleration from a standstill with the accelerator pedal OFF, and the return control is performed according to the flowchart in Figure 2. Time t1 in Figure 4 is the time when the return condition is met by the pressing of the accelerator pedal 54, the judgment of S1 becomes YES, and the engagement control from S2 onwards begins, and the engagement control of the lock-up clutch 30 according to the power source torque estimate value Tdest, i.e., the control of the lock-up differential pressure Plu, begins. Before time t1, the engine 12 is in an idle state, and the differential rotation ΔN is approximately the idle rotation speed. The indicated value of the lock-up differential pressure Plu in the bottom row of Figure 4 is the same value as the target value Plut calculated according to the above formula (2), and is calculated using the required torque capacity Tlu obtained according to formula (1) by multiplying the power source torque estimate value Tdest by the control gain G, so the correction by the control gain G is reflected. To specifically explain the case where the control gain G changes as the engagement control of the lock-up clutch 30 progresses, as shown by points a → b → c in Figure 3, at the beginning of the engagement control, the differential rotation ΔN is large, and there is a response delay in the rise of the estimated power source torque Tdest based on the engine torque Te, so the control gain G is a relatively large value (point a). For this reason, as shown in time t1~t2, the multiplied value Tdest×G, obtained by multiplying the estimated power source torque Tdest by the control gain G, becomes larger than the estimated power source torque Tdest, and the differential rotation ΔN is rapidly reduced based on the relatively large lock-up differential pressure Plu. As the differential rotation ΔN decreases, the control gain G decreases (point b), so as shown in time t2~t3, the multiplied value Tdest×G becomes less than or equal to the estimated power source torque Tdest. As a result, the lock-up differential pressure Plu is kept relatively low, the slip-engaged state of the lock-up clutch 30 is maintained, and engagement shock due to sudden engagement is suppressed. Furthermore, as the estimated power source torque Tdest increases in that state, the control gain G increases accordingly (point c), and the multiplicative value Tdest × G becomes greater than the estimated power source torque Tdest, as shown in time t3~t4.As a result, the lock-up clutch 30 is quickly engaged with a relatively large lock-up differential pressure Plu, suppressing engine torque Te overshoot and judder. Time t4 is the time when the engagement determination is successful, the judgment in S7 becomes YES, and the control termination process in S8 begins.

[0034] As described above, the neutral control unit 78 functionally provided in the electronic control device 70 of the vehicle 10 of this embodiment controls the lock-up differential pressure Plu based on the estimated power source torque Tdest to engage the lock-up clutch 30. The control gain G is determined based on the data map in Figure 3, which is predetermined with the estimated power source torque Tdest and differential rotation ΔN as variables, and the lock-up differential pressure Plu is controlled according to the multiplicative value Tdest × G obtained by multiplying the estimated power source torque Tdest by the control gain G. In this case, the data map of the control gain G is determined such that the control gain G increases as the differential rotation ΔN increases, and the control gain G increases as the estimated power source torque Tdest increases. As the lock-up differential pressure Plu increases as the control gain G increases, even when the power source torque Td increases due to the depressing operation of the accelerator pedal 54, the lock-up clutch 30 can be engaged without limiting the power source torque Td, while suppressing the occurrence of judder and engagement shock. This results in a faster rise of the power source torque Td and improved drivability such as driving force responsiveness. In other words, the data map in Figure 3, which is used to determine the control gain G using the estimated power source torque Tdest and the differential rotation ΔN as variables, is determined in advance through experiments or other means so that the lock-up clutch 30 can be engaged while suppressing the occurrence of judder and engagement shock.

[0035] On the other hand, since the control gain G is determined using the differential rotation ΔN as a variable, the lock-up differential pressure Plu of the lock-up clutch 30 can be appropriately controlled and engaged based on the actual differential rotation ΔN, regardless of calculation errors in the power source torque estimate Tdest, control errors in the lock-up differential pressure Plu, response delays, etc. In other words, when controlling the lock-up differential pressure Plu based on the power source torque estimate Tdest, the control may become unstable due to the effects of such calculation errors and control errors. However, by detecting the actual differential rotation ΔN of the lock-up clutch 30 and controlling the lock-up differential pressure Plu in a feedback manner, the effects of calculation errors and control errors are reduced, and the engagement control of the lock-up clutch 30 can be performed stably. During the engagement transient of the lock-up clutch 30 in a slip-engaged state, the friction characteristics change depending on whether it is static or dynamic friction. However, since the control gain G is determined using the differential rotation ΔN as a variable, the change in friction characteristics can also be absorbed by the control gain G.

[0036] Furthermore, this embodiment relates to neutral control, and not only when the accelerator pedal 54 is depressed as a return condition, but also when the accelerator pedal 54 is depressed during the return even if it is not a return condition, the effects of the present invention can be appropriately obtained, such as being able to engage the lock-up clutch 30 while suppressing the occurrence of judder and engagement shock without limiting the power source torque Td.

[0037] Furthermore, in this embodiment, a lock-up clutch 30 provided on the torque converter 14 is used as a disconnection device. In the control of the lock-up differential pressure Plu, the input torque is affected by the torque transmission by the torque converter 14. However, since the control gain G is determined using the differential rotation ΔN of the lock-up clutch 30 as a variable, it is possible to absorb the effect of torque transmission by the torque converter 14, and the engagement control of the lock-up clutch 30 becomes easier. In other words, the data map in Figure 3 for determining the control gain G using the power source torque estimate Tdest and differential rotation ΔN as variables is determined so that the lock-up clutch 30 can be appropriately engaged regardless of the torque transmission by the torque converter 14.

[0038] Although embodiments of the present invention have been described in detail above with reference to the drawings, this is merely one embodiment, and the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art. [Explanation of symbols]

[0039] 10: Vehicle 12: Engine (power source) 14: Torque converter 16: Automatic transmission 20: Drive wheels 30: Lock-up clutch (disconnection device) 70: Electronic control unit (control unit) 78: Neutral control unit (engagement control unit) ΔN: Differential rotation Tdest: Estimated power source torque (estimated value of power source torque) G: Control gain Tdest×G: Multiplicative value Plu: Lock-up differential pressure (engagement transient pressure)

Claims

1. This applies to a vehicle having a power source including an engine, and a friction-engagement type disconnecting device that connects and disconnects the power transmission path between the power source and the drive wheels. In a vehicle control device equipped with an engagement control unit that controls the engagement transient pressure of the disconnection device when engaging the disconnection device, The engagement control unit determines a control gain based on a predetermined relationship between the estimated power source torque, which is the torque of the power source, and the difference rotation of the disconnection device, and controls the engagement transient pressure according to the multiplied value obtained by multiplying the control gain by the estimated power source torque, The predetermined relationship is such that the control gain increases as the difference in rotational speed increases, and the control gain increases as the estimated value of the power source torque increases, and the engagement transient pressure increases as the control gain increases, and the vehicle is equipped with a torque converter and an automatic transmission in series from the power source side in the power transmission path between the power source and the drive wheels, and the torque converter is provided with a lock-up clutch, and the lock-up clutch is the engagement / disengagement device, The engagement control unit calculates the required torque capacity Tlu according to equation (1) using the inertia Ilu of the lock-up clutch, the target angular acceleration α, the estimated power source torque Tdest, and the control gain G, and calculates the target value Plut of the lock-up differential pressure corresponding to the engagement transient pressure according to equation (2) using the required torque capacity Tlu, the hydraulic conversion coefficient K, and the friction coefficient μ, and engages the lock-up clutch with the target value Plut. Tlu=Tdest×G-Ilu×α...(1) Plut=Tlu / K / μ...(2) A vehicle control device characterized by the following features.

2. The system has a neutral control unit that opens the disconnection device to interrupt the power transmission path when predetermined neutral control execution conditions are met, and engages the disconnection device when predetermined return conditions are met. When the neutral control unit satisfies the return condition and engages the disconnection device, the engagement transient pressure of the disconnection device is controlled by the engagement control unit. The vehicle control device according to feature 1.

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