JP7600718B2 - 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.

Here, an unusual starting operation by the driver refers to an operation in which, for example, when starting on a downhill slope, the transmission is left in neutral, that is, the vehicle is started without being shifted into any gear, and the transmission is shifted into gear once the vehicle speed has increased to a certain extent.

JP 2005-76667 A

In a power transmission device that has a variable speed clutch between a torque converter with a lock-up clutch and a gear change mechanism, it is possible to avoid changing the state of the lock-up clutch during a gear change operation in order to avoid affecting the control of the variable speed clutch.

In this case, the lockup clutch cannot be engaged until the shift is complete, so the lockup region cannot be expanded. For this reason, in a power transmission device configured as described above, it is desirable to expand the lockup region without affecting the control of the shift clutch.

However, the power transmission device described in Patent Document 1 does not take into consideration the control of the shift clutch and lock-up clutch during the shift operation, and there is still room for improvement.

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 expand the lock-up region without affecting the control of the shift clutch.

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 internal combustion engine; a transmission mechanism that changes the speed of the internal combustion engine at a speed ratio corresponding to a gear stage and outputs the rotation; a transmission clutch that is provided between the torque converter and the transmission mechanism and can be switched to an engaged state in which power is transmitted or a disconnected state in which power is disconnected; and a clutch actuator that automatically operates the transmission clutch, the control device including a control unit that controls engagement or release of the lock-up clutch, the control unit being capable of completing the switching of the lock-up clutch from release to engagement during a shift operation that switches the gear stage of the transmission mechanism and when the transmission clutch is in the disconnected state, and executing a shift-in-progress pre-charge that temporarily increases a command pressure for the lock-up clutch before engaging the lock-up clutch during the shift operation and then waits in a state where the command pressure is maintained at a first pressure, and the shift-in-progress pre-charge is configured to be completed by the time the transmission clutch during the shift operation switches to the disconnected state .

The present invention provides a control device for a vehicle drive unit that can expand the lockup region without affecting the control of the shift clutch.

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 flowchart showing a flow of processing for lock-up control executed by the control device for a vehicle drive device according to one embodiment of the present invention. FIG. 3 is an example of a timing chart showing a gear shift operation in a vehicle equipped with a control device for a vehicle drive device according to an 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 internal combustion engine, a speed change mechanism that changes the speed of the internal combustion engine at a speed ratio corresponding to the speed change stage and outputs the rotation, a speed change clutch that is provided between the torque converter and the speed change mechanism and can be switched to an engaged state that transmits power or a disconnected state that disconnects power, and a clutch actuator that automatically operates the speed change clutch, and includes a control unit that controls the engagement or release of the lock-up clutch, and is characterized in that the control unit completes the switching of the lock-up clutch from release to engagement when a speed change operation that switches the speed change stage of the speed change mechanism is in progress and the speed change clutch is in a disconnected state. As a result, the control device for a vehicle drive device according to one embodiment of the present invention can expand the lock-up region without affecting the control of the speed change clutch.

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 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 (operating 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 speed sensor 51, a clutch 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 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 speed sensor 51 detects the rotation speed of the turbine shaft 36 (hereinafter referred to as "turbine speed"). The clutch speed sensor 52 detects the rotation speed of the clutch disc 32b and the input shaft 37 (hereinafter referred to as "clutch 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, at least the engagement 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 the 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 functions as a clutch control unit 101 that controls the variable-speed clutch 32 by referring to a map (not shown) that defines the relationship between the clutch position and the clutch transmission torque based on the clutch position detected by the clutch position detection sensor 53.

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. The lockup clutch control unit 102 in this embodiment constitutes a control unit.

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.

In the above-mentioned lockup control, the control device 10 executes a precharge in which the command pressure for the lockup clutch 35 (hereinafter referred to as the "LU command pressure") is temporarily increased to a predetermined precharge pressure before the lockup clutch 35 is engaged, and then the command pressure is maintained at the predetermined pressure and kept on standby. The precharge is an operation for filling the apply chamber with hydraulic oil in order to shorten the response time of the lockup clutch 35 (the time from when a lockup command is issued until the lockup clutch 35 actually engages), and the command pressure is set taking into consideration the response delay due to the flow resistance of the hydraulic oil itself. Specifically, the precharge aims to put the lockup clutch 35 in a state where it starts engaging (transmitting power) early, and in this embodiment, it also means waiting in a state just before engagement so that the operation of engaging the lockup clutch 35 can start immediately when other conditions are in a state where the lockup clutch 35 can start engaging.

The above-mentioned LU command pressure is the hydraulic pressure commanded from the control device 10 to the hydraulic control device 40, and is the command value of the differential pressure between the engagement hydraulic pressure and the release hydraulic pressure.

In the above-mentioned lockup control, when the lockup clutch 35 is to be fully engaged, the control device 10 increases the LU command pressure to the engagement command pressure P5, and engages the lockup clutch 35 in one go. This causes the operating oil pressure of the lockup clutch 35 to be increased in one go, and the lockup clutch 35 completes engagement early. The engagement command pressure P5 is set to a pressure greater than each precharge pressure, which will be described later. Note that, when maintaining the engagement of the lockup clutch 35, the LU command pressure may be left at the engagement command pressure P5, but it may be reduced to an LU command pressure lower than the engagement command pressure P5 within a range that does not cause slippage.

In this embodiment, there are various types of precharge for the lockup clutch 35, including at least a normal precharge, a precharge during gear shifting, and a precharge when starting, and the control device 10 selectively executes these precharges depending on the situation.

Normal precharge is executed, for example, when the shift mechanism 31 is not in a shift operation to switch gears or when the vehicle 1 is not starting, and is a precharge in which the LU command pressure is temporarily increased to the normal precharge pressure (hereinafter referred to as "normal precharge pressure Pn") before the lock-up clutch 35 is engaged, and then the LU command pressure is kept at the first pressure P2. In other words, normal precharge is a precharge control in a state in which the shift clutch 32 is engaged, and is a precharge control in a state in which there is no release of the shift clutch 32 or no transition control or operation between the released and engaged states.

Pre-charge during gear shifting is executed during a gear shift operation that switches gear stages in the gear shift mechanism 31, and involves temporarily increasing the LU command pressure to the pre-charge pressure during gear shifting (hereinafter referred to as "pre-charge pressure during gear shifting P3") before the lock-up clutch 35 is engaged, and then maintaining it at the first pressure P2 while it waits. In other words, pre-charge during gear shifting is pre-charge control when the gear shift clutch 32 is disengaged or in transition between the disengaged and engaged states.

The precharge during gear shifting is executed during a gear shift operation, and more specifically, is executed in either of the following cases (1) or (2).
(1) When a predetermined lock-up condition is satisfied and a shift command is issued at the same time. (2) When a predetermined lock-up condition is satisfied after a shift command is issued, and it is determined that pre-charge during shifting can be completed before the shift clutch 32 switches from the engaged state to the disengaged state.

The first pressure P2 is a pressure lower than the pre-charge pressure P3 during shifting and the normal pre-charge pressure Pn, and is a pressure that is increased in advance so that the engagement of the lock-up clutch 35 can be completed quickly. Specifically, it is an instruction pressure that realizes the pressure at which the lock-up clutch 35 is in a state (maintains a state) at which it starts to engage (transmit power), and is determined in advance experimentally and stored in the ROM of the control device 10. In this embodiment, the standby pressure for both normal pre-charge and pre-charge during shifting is the first pressure P2, but they may be different pressures.

The pre-charge pressure during shifting P3 and the normal pre-charge pressure Pn are LU command pressures that are temporarily increased so that the pressure difference between the engagement and release hydraulic pressures of the lock-up clutch 35 quickly reaches the first pressure P2. As mentioned above, pre-charge is an operation to fill the apply chamber with hydraulic oil in order to shorten the response time of the lock-up clutch 35, and the command pressure is set taking into account the response delay caused by the flow resistance of the hydraulic oil itself. For this reason, the pre-charge command pressure and pre-charge time are set taking into account the viscosity of the hydraulic oil, which depends on temperature, and the flow characteristics of the oil passages and valves.

Since the pre-charge during shifting is to prepare for completing the engagement of the lock-up clutch 35 while the shift clutch 32 is in the disengaged state, the pre-charge during shifting is completed during the shifting operation before the shift clutch 32 switches from the engaged state to the disengaged state. However, when the pre-charge during shifting is performed in this way, the shift clutch 32 is in a state in which it transmits power (engaged state or in transition from the engaged state to the disengaged state), so if the pre-charge pressure during shifting P3 is made too high, the operating oil pressure of the lock-up clutch 35 will suddenly increase, and the lock-up clutch 35 will engage and transmit torque, which may cause torque fluctuations (shocks). In particular, when the pre-charge during shifting is performed, the shift clutch 32 changes from an engaged state to a disengaged state, and the driving force (input) input from the torque converter 30 to the shift clutch 32 will change when the torque transmitted by the shift clutch 32 is changing, so there is a high possibility that a shock felt by the occupant will occur. Furthermore, when the vehicle is accelerating, the change in driving force is also large, which is particularly noticeable. Such shocks are transmitted to the drive wheels 4, causing changes in the acceleration of the vehicle body (vibrations), which reduces the marketability of the vehicle.

Therefore, in this embodiment, the pre-charge pressure P3 during shifting is set to a value lower than the normal pre-charge pressure Pn. This prevents the occurrence of shocks caused by a sudden increase in the hydraulic pressure of the lock-up clutch 35.

The start-up precharge is executed when the vehicle 1 starts, specifically when the driver's depression of the accelerator pedal is detected. The LU command pressure is temporarily increased to the start-up precharge pressure (hereinafter referred to as "start-up precharge pressure P4"), and then the pressure is maintained at the second pressure P1.

The second pressure P1 is lower than the first pressure P2 described above and lower than the starting precharge pressure P4, and is a pressure that is increased in advance to allow for early completion of the filling of hydraulic oil for removing backlash in the lock-up clutch piston (not shown), and is experimentally determined in advance and stored in the ROM of the control device 10.

The starting precharge pressure P4 is an LU command pressure that is temporarily increased so that the pressure difference between the engagement and release hydraulic pressures of the lock-up clutch 35 quickly reaches the second pressure P1, and is a pressure higher than the above-mentioned precharge pressure P3 during gear shifting and the normal precharge pressure Pn.

The start-up pre-charge is set to be completed in a shorter time than the pre-charge during gear shifting described above. Even if torque transmission occurs in the lock-up clutch 35 and some torque fluctuation occurs due to the temporary increase in LU command pressure in a short time, the driver will not feel uncomfortable when the vehicle 1 is starting. Furthermore, when the vehicle 1 is starting, a delay occurs in the actual flow of hydraulic oil due to the high viscosity of the hydraulic oil and the flow resistance of the oil passage, so a sudden change in the LU command pressure is unlikely to cause a sudden increase in the actual hydraulic oil pressure. Therefore, no problems will occur even if the start-up pre-charge is completed in a short time.

In contrast, pre-charge during gear shifting is performed over a longer period of time than pre-charge at start. When vehicle 1 is traveling, including during gear shifting, the driver is more likely to feel changes in acceleration, and so even slight torque fluctuations may cause the driver to feel uncomfortable. In addition, when vehicle 1 is traveling, including during gear shifting, the viscosity of the hydraulic oil may decrease or the flow resistance may change depending on the temperature, resulting in high responsiveness of the actual hydraulic oil pressure.

For this reason, if the LU command pressure is suddenly increased in a short period of time, the actual hydraulic pressure may also suddenly increase, which may cause the torque fluctuations described above. Therefore, it is preferable that pre-charge during gear shifting is performed over a longer period of time than pre-charge at start-up, as described above.

(Lock-up control)
Next, the flow of processing of the lock-up control executed by the control device 10 of this embodiment will be described with reference to FIG.

As shown in FIG. 2, the control device 10 determines whether or not a predetermined lock-up condition is satisfied (step S1). If the control device 10 determines in step S1 that the predetermined lock-up condition is not satisfied, it repeats the process of step S1.

When the control device 10 determines in step S1 that the predetermined lock-up condition is satisfied, it determines whether or not a gear shift command has already been issued, i.e., whether or not a gear shift command was issued when the predetermined lock-up condition was satisfied (step S2).

The control device 10 operates a shift actuator (not shown) to change the gear in the transmission mechanism 31 by referring to a shift map based on the vehicle speed and the amount of depression of the accelerator pedal (shift-related parts other than the shift clutch 32 are omitted in FIG. 1), and can determine whether or not a shift command has been issued. The shift map is a map in which the vehicle speed and the amount of depression of the accelerator pedal correspond to shift lines, and is experimentally obtained in advance and stored in the ROM of the control device 10.

If the control device 10 determines in step S2 that there is no gear shift command, it executes normal precharge (step S9) and proceeds to processing in step S8.

When the control device 10 determines in step S2 that a shift command has been issued, it determines whether the shift clutch 32 is transitioning from an engaged state to a disengaged state (step S3). The control device 10 can determine whether the shift clutch 32 is transitioning from an engaged state to a disengaged state, for example, based on the clutch position. In addition, the control device 10 can also determine whether the shift clutch 32 is transitioning from an engaged state to a disengaged state, for example, based on the elapsed time since the shift command. Whether the shift clutch 32 is transitioning from an engaged state to a disengaged state may be determined by other methods, not limited to the methods described above.

When the control device 10 determines in step S3 that the shift clutch 32 is not in transition from an engaged state to a disengaged state, it ends this lock-up control. In other words, a predetermined lock-up condition is met and an attempt is made to engage the lock-up clutch 35, but the shift control for the shift mechanism 31 and the shift clutch 32 is in an advanced state, and in order not to adversely affect the shift control, the lock-up clutch 35 is not engaged (specifically, pre-charged) until the shift control is terminated. In contrast, when the control device 10 determines in step S3 that the shift clutch 32 is in transition from an engaged state to a disengaged state, it changes the LU command pressure to the shift pre-charge pressure P3 (step S4). In other words, if the shift control has just started, it starts engaging the lock-up clutch 35 (specifically, pre-charged).

Then, the control device 10 determines whether or not a predetermined time (between time t1 and time t2) has elapsed for the instruction to set the LU command pressure to the pre-charge pressure during shifting P3 (step S5). The predetermined time is set to a time that is at least shorter than the time it takes for the shift clutch 32 to switch from the engaged state to the disengaged state. If the control device 10 determines in step S5 that the predetermined time has not elapsed, it repeats the process of step S5. In other words, the control device 10 continues to issue the instruction to pre-charge, with the LU command pressure set to the pre-charge pressure during shifting P3, until the predetermined time has elapsed.

When the control device 10 determines in step S5 that the predetermined time has elapsed, it changes the LU command pressure from the pre-charge pressure during shifting P3 to the first pressure P2 (step S6). In other words, the control device 10 issues a command to maintain the hydraulic pressure state at which the lock-up clutch 35 can start to be engaged, assuming that the predetermined time has elapsed and pre-charge has been completed.

Then, the control device 10 determines whether the shift clutch 32 is in a disengaged state (step S7). If the control device 10 determines in step S7 that the shift clutch 32 is not in a disengaged state, it determines that the shift clutch 32 has not yet transitioned to a disengaged state, and repeats the process of step S7. In other words, the control device 10 waits with the LU command pressure set to the first pressure P2 until the shift clutch 32 is in a disengaged state in step S7.

If the control device 10 determines in step S7 that the shift clutch 32 is in a disengaged state, it proceeds to step S8.

In step S8, the control device 10 changes the LU command pressure from the first pressure P2 to the engagement command pressure P5 (step S8) and ends this lock-up control. By executing step S8, the hydraulic pressure of the hydraulic oil pressure is increased and the lock-up clutch 35 is engaged.

In this way, the control device 10 can execute the operation of changing the state of the lockup clutch 35 to engaged only when the shift clutch 32 is transitioning from an engaged state to a disengaged state. During other shift operations, the control device 10 suppresses the operation of changing the state of the lockup clutch 35 to engaged. When the shift clutch 32 is in a disengaged state during a shift operation, the control device 10 instructs the lockup clutch 35 to be switched from released to engaged. The operation of switching the lockup clutch 35 from released to engaged can be completed in a short time because pre-charging is also performed, so that the shift stage in the shift mechanism 31 can be completed in a time shorter than the time it takes to change from 1st gear to 2nd gear.

Next, referring to FIG. 3, the transition of the LU command pressure during a shift operation from 1st gear to 2nd gear in the vehicle 1 of this embodiment will be described. FIG. 3 shows an example in which a shift command from 1st gear (denoted as "1st" in FIG. 3) to 2nd gear (denoted as "2nd" in FIG. 3) and a lock-up command, i.e., the establishment of a predetermined lock-up condition, are issued simultaneously.

As shown in FIG. 3, at time t0, the specified lockup condition is not satisfied, i.e., the lockup command has not been issued (indicated as "OFF" in FIG. 3), and the vehicle 1 is accelerating in first gear.

At time t0, the clutch position is the position when the variable speed clutch 32 is engaged (indicated as "engaged" in FIG. 3), and the LU command pressure is maintained at the second pressure P1. Also, since the vehicle is accelerating, the engine speed Ne, turbine speed Nt, and clutch speed Nc are increasing over time.

After that, at time t1, when a shift command from 1st gear to 2nd gear is issued and at the same time a lock-up command is issued (indicated as "ON" in FIG. 3), the shift clutch 32 starts to transition from an engaged state to a disengaged state. This causes the clutch position to transition from a position indicating engagement to a position when the shift clutch 32 is in a disengaged state (indicated as "disengaged" in FIG. 3).

Furthermore, at time t1, pre-charge during shifting is started, and the LU command pressure is increased from the second pressure P1 to the pre-charge pressure during shifting P3.

After that, at time t2, when a predetermined time has elapsed since the start of pre-charge during gear shifting, the LU command pressure is changed to the first pressure P2, and pre-charge during gear shifting is completed. Also, around time t2, as the gear shift clutch 32 transitions from an engaged state to a disengaged state, the clutch rotation speed Nc begins to decrease relative to the turbine rotation speed Nt. As a result, the driving force of the vehicle 1 decreases, and the acceleration of the vehicle 1 also decreases.

After that, at time t3, when the clutch position reaches a position indicating disengagement and the shift clutch 32 enters a disengaged state, the LU command pressure is increased from the first pressure P2 to the engagement command pressure P5. This starts the lockup clutch 35 switching from a released state to an engaged state, and then while the shift clutch 32 is disengaged (in the example shown in FIG. 3, between times t3 and t4), the lockup clutch 35 is fully engaged. In other words, the lockup clutch 35 switches to an engaged state, and the control to engage the lockup clutch 35 is completed.

In the example shown in FIG. 3, at time t3, the LU command pressure is increased from the first pressure P2 to the engagement command pressure P5 at the same time that the shift clutch 32 is disengaged. However, if it is possible to switch the lock-up clutch 35 to the engagement state while the shift clutch 32 is disengaged, the LU command pressure does not have to be increased from the first pressure P2 to the engagement command pressure P5 at the same time that the shift clutch 32 is disengaged. For example, the LU command pressure may be increased from the first pressure P2 to the engagement command pressure P5 after time t3.

As described above, between time t3 and time t4, when the lock-up clutch 35 switches to the engaged state, the engine speed Ne and the turbine speed Nt are synchronized, and as a result, the speed difference between the engine speed Ne and the turbine speed Nt (represented as "|Ne-Nt|" in Figure 3) becomes zero.

Furthermore, between time t3 and time t4, the gear shift stage in the transmission mechanism 31 is changed from first gear to second gear. As a result, from time t3, the clutch rotation speed Nc starts to decrease toward the rotation speed corresponding to second gear, and around time t4, the change to second gear in the transmission mechanism 31 is almost completed, and the clutch rotation speed Nc becomes the rotation speed corresponding to second gear.

After that, at time t4, the shift clutch 32 starts to switch from the disengaged state to the engaged state, and the clutch position gradually transitions toward a position indicating engagement.

After time t4 has elapsed, the engine speed Ne decreases to synchronize with the clutch speed Nc as the variable speed clutch 32 transitions to an engaged state. Then, as engine power is transmitted, acceleration resumes and the clutch speed Nc increases (the vehicle speed increases).

Then, at time t5, when the clutch position reaches a position indicating engagement and the shift clutch 32 enters an engaged state, the engine speed Ne and turbine speed Nt are synchronized with the clutch speed Nc, and the shift to second gear is completed.

As described above, the control device for the vehicle drive device in this embodiment is configured to complete the switching of the lock-up clutch 35 from disengagement to engagement when a gear shift operation is in progress and the gear shift clutch 32 is in a disengaged state.

With this configuration, the control device for the vehicle drive device according to this embodiment can engage the lock-up clutch 35 before the shift is complete, without waiting for the lock-up clutch 35 to be engaged until the shift is complete. This allows the lock-up region to be expanded without affecting the control of the shift clutch 32. This allows for improved fuel economy.

The control device for the vehicle drive device according to this embodiment is also configured to complete the switching of the lock-up clutch 35 from released to engaged during the shift operation while the shift clutch 32 is in the disengaged state when the establishment of a predetermined lock-up condition and a shift command are issued simultaneously, or when the establishment of a predetermined lock-up condition is issued after a shift command and it is determined that pre-charge during shifting can be completed before the shift clutch 32 switches from the engaged state to the disengaged state.

As a result, the control device for the vehicle drive device according to this embodiment does not need to change the control of the variable speed clutch 32 to take into account the engagement of the lock-up clutch 35, which prevents the control of the variable speed clutch 32 from becoming complicated.

Furthermore, the control device for the vehicle drive device according to this embodiment can engage the lock-up clutch 35 before the shift is completed without waiting for the shift to be completed and without affecting the control of the shift clutch 32.

The control device for the vehicle drive device according to this embodiment is also capable of performing pre-charge during shifting before the lock-up clutch 35 is engaged during a shifting operation, and is configured to complete the pre-charge during shifting before the shifting clutch 32 during the shifting operation switches to a disengaged state.

With this configuration, the control device for the vehicle drive device according to this embodiment can reduce the time required to switch the lock-up clutch 35 from a released state to an engaged state by performing pre-charge during gear shifting.

The control device for the vehicle drive device according to this embodiment is also capable of executing start-time precharge when the vehicle 1 starts, and the start-time precharge pressure P4 during the start-time precharge is set to a pressure higher than the precharge pressure P3 during gear shifting.

As a result, the control device for the vehicle drive system according to this embodiment can complete the removal of backlash in the lock-up clutch piston earlier when the vehicle 1 starts compared to during a gear shift operation.

The control device for the vehicle drive device according to this embodiment is also configured to perform pre-charge during gear shifting for a longer period of time than pre-charge at start-up.

With this configuration, the control device for the vehicle drive device according to this embodiment can suppress a sudden increase in the actual hydraulic pressure, and can suppress the driver from feeling uncomfortable due to torque fluctuations.

In this embodiment, for example, at time t3 in FIG. 3, an example has been described in which the LU command pressure is instantly increased from the first pressure P2 to the engagement command pressure P5, but this is not limiting, and the LU command pressure may be gradually increased from the first pressure P2 to the engagement command pressure P5. Also, even when the shift clutch 32 is not in a disengaged state, the LU command pressure may be gradually increased toward the engagement command pressure P5.

In this case, it is preferable that the rate of increase of the LU command pressure is set to be faster when the shift clutch 32 is disengaged than when the shift clutch 32 is not disengaged. This is because it is necessary to switch the lock-up clutch 35 to the engaged state while the shift clutch 32 is disengaged during a shift operation.

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 (internal combustion 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 102 Lock-up clutch control unit (control unit)
Pn Normal precharge pressure P1 Second pressure P2 First pressure P3 Precharge pressure during shifting P4 Precharge pressure at start P5 Engagement command pressure

Claims (4)

a torque converter with a lock-up clutch connected to the internal combustion engine;
a speed change mechanism that changes the rotation of the internal combustion engine at a speed change ratio corresponding to a speed change stage and outputs the 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 engagement or release of the lock-up clutch,
The control unit completes switching of the lock-up clutch from release to engagement when a gear shift operation for switching the gear stage of the transmission mechanism is in progress and the gear shift clutch is in the disengaged state,
During the shift operation, a pre-charge during shifting can be executed in which a command pressure for the lock-up clutch is temporarily increased before the lock-up clutch is engaged and then the command pressure is maintained at a first pressure,
4. The control device for a vehicle drive system, wherein the precharge during the shift is completed before the shift clutch during the shift operation is switched to a disengaged state . The control unit is capable of executing a start pre-charge in which, when the vehicle starts, a command pressure for the lock-up clutch is temporarily increased and then the command pressure is kept at a second pressure lower than the first pressure,
2. The control device for a vehicle drive device according to claim 1, wherein the command pressure temporarily increased before being maintained at the second pressure during the start precharge is higher than the command pressure temporarily increased during the shift precharge. 3. The control device for a vehicle drive device according to claim 2 , wherein the pre-charge during gear shifting is executed for a longer period of time than the pre-charge at start-up. 4. The control device for a vehicle drive device according to claim 1 , wherein the increasing rate of the command pressure for engaging the lock-up clutch is faster when the variable speed clutch is in the disengaged state than when the variable speed clutch is not in the disengaged state.

Images