JP2002130461A - Automatic transmission slip lock-up control device - Google Patents

Abstract

(57) [Problem] To prevent the driving force from deteriorating due to a large change in the engagement force of a lock-up clutch controlled by slip lock-up when a drive coast is switched. When the drive is switched from coast to coast or from coast to drive during slip lock-up control, the lock-up clutch engagement pressure command value Plu is set to a preset value IN for a predetermined time DCTIM after the switch.
It is fixed to ITRSCD and INITRSDC, and when the predetermined time DCTIM has elapsed, the engagement pressure command value Plu is determined based on the absolute values of the target slip rotation speed, the actual slip rotation speed, and the engine output torque.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a slip lock-up control device for an automatic transmission, and more particularly to a slip lock-up control for controlling a rotational speed difference between an input shaft and an output shaft of a torque converter.

[0002]

2. Description of the Related Art Conventionally, in an automatic transmission provided with a lock-up clutch for mechanically directly connecting an input shaft and an output shaft of a torque converter, a difference in rotational speed between an input shaft and an output shaft of the torque converter (hereinafter referred to as a "rotation speed difference"). Slip lock-up control (half-clutch control) for controlling the engagement force of the lock-up clutch so as to make the slip rotational speed coincide with a target value is known.

An apparatus for performing the slip lock-up control has been disclosed in Japanese Patent Application Laid-Open No. 11-08726. According to this method, a target converter torque is calculated based on a deviation between a detected value of the slip rotation speed and a target value of the slip rotation speed, and an engine output torque is estimated from a throttle opening and an engine rotation speed. The configuration is such that a lockup clutch engagement pressure command value is calculated from the torque and the engine output torque.

[0004]

However, in the above-described conventional slip lock-up control device, the drive state shifts to the coast state, and the magnitude relationship between the input shaft side rotation speed and the output shaft side rotation speed is reversed. If the slip rotation speed turns negative, the engine output torque turns negative due to the coasting condition, and the target slip rotation speed is set to a negative value, the actual slip rotation speed is reduced in normal times. Since the reverse characteristic to the control for approaching the target slip rotation speed is required, if the control is performed as it is, the control is performed in a direction away from the target, and the lock-up clutch is shifted to the target slip lock state (target slip lock state). There is a problem that the control cannot be performed to the half-clutch state) (see FIG. 6).

[0005] Also, from the drive state to the coast state,
Alternatively, at the time of switching from the coast state to the drive state, the engine output torque changes across 0, and shows a sudden increase or decrease as an absolute value. Therefore, the engagement pressure command value calculated based on the engine output torque Greatly fluctuates, and the slip lock-up control becomes unstable, which may deteriorate the drivability.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a slip lock-up control device for an automatic transmission that can reliably perform slip lock-up control even when a coast state occurs. Aim.
Also, even when switching from the drive state to the coast state or from the coast state to the drive state,
An object of the present invention is to provide a slip lock-up control device for an automatic transmission that can perform slip lock-up control without deteriorating drivability.

[0007]

According to the first aspect of the present invention, a slip rotation speed, which is a rotation speed difference between an input shaft and an output shaft of a torque converter, is detected, and the detected slip rotation speed and a target slip rotation speed are detected. A slip lock-up control device for an automatic transmission configured to determine an engagement pressure command value for a lock-up clutch based on a deviation from a speed and an output torque of the engine. The engagement pressure command value is determined based on the absolute value of each output torque.

With this configuration, even when the drive state is switched to the coast state and the rotational speed of the input shaft of the torque converter becomes lower than the rotational speed of the output shaft, the absolute value of the slip rotational speed at that time is obtained. Is used to determine the engagement pressure command value. Similarly, even when the drive state is switched to the coast state and the engine output torque becomes negative, the absolute value of the engine output torque at that time determines the engagement pressure command value. Used for Further, even if the target slip rotation speed is set to a negative value, the absolute value of the target slip rotation speed at that time is used for determining the engagement pressure command value.

According to the second aspect of the present invention, a slip rotational speed which is a rotational speed difference between an input shaft and an output shaft of the torque converter is detected, a deviation between the detected slip rotational speed and a target slip rotational speed, and In the lockup control device for an automatic transmission configured to determine the engagement pressure command value of the lockup clutch based on the output torque of the engine, the lockup control device is set in advance when switching between the drive state and the coast state. The fixing pressure command value is fixed to a preset value for a given time.

With this configuration, when switching from the drive state to the coast state or from the coast state to the drive state, the engagement pressure command value is determined based on the slip rotation speed, the target slip rotation speed, and the output torque of the engine. By priority, the engagement pressure command value is fixed at a predetermined value for a predetermined time. According to a third aspect of the present invention, the engagement pressure command value is fixed to a preset value for the preset time, and the feedback operation for eliminating the deviation is stopped.

With this configuration, when switching between the drive state and the coast state, and when the engagement pressure command value is fixed, the deviation is eliminated and the actual slip rotation speed is reduced to the target slip rotation speed. The feedback operation for matching the speed is stopped, and even if there is a deviation (control error), the engagement pressure command value is fixed at a predetermined value, and the progress of the integration operation is stopped.

According to the fourth aspect of the present invention, the engagement pressure command value is fixed to a different value depending on whether the state is switched from the drive state to the coast state or the state is switched from the coast state to the drive state. The configuration was adopted. According to this configuration, at the time of switching between the drive state and the coast state, the engagement pressure command value that is different according to the switching direction is fixed for a predetermined time.

According to the fifth aspect of the present invention, when switching between the drive state and the coast state, the engagement pressure command value is fixed at a predetermined value for a predetermined time. In this configuration, the engagement pressure command value is determined based on the absolute values of the slip rotation speed, the target slip rotation speed, and the output torque of the engine.

With this configuration, usually, the engagement pressure command value is determined based on the absolute values of the slip rotation speed, the target slip rotation speed, and the engine output torque, but the switching between the drive state and the coast state is performed. At the time of replacement, the engagement pressure command value is fixed at a preset value for a preset time.

[0015]

According to the first aspect of the present invention, since the engagement pressure command value is determined based on the absolute values of the slip rotation speed, the target slip rotation speed, and the output torque of the engine, the drive state and the coast state are determined. In both cases, there is an effect that the slip lock-up control for bringing the slip rotation speed close to the target can be performed by the same processing.

According to the second aspect of the present invention, when the engine output torque changes across 0 and the engagement pressure command value based on the engine output torque becomes unstable, the engagement pressure command value is set to a preset value instead. Since the pressure command value is fixed, there is an effect that the stability of the slip lock-up control when switching between the drive state and the coast state can be improved.

According to the third aspect of the invention, the feedback operation is stopped when the engagement pressure command value is fixed at the predetermined value, so that the engagement pressure command value can be stably maintained at the predetermined value, and the feedback is integrated. When the operation is included, it is possible to prevent the deviation from being unnecessarily integrated, and it is possible to ensure the controllability at the time of resuming the feedback. According to the fourth aspect of the present invention, there is an effect that the engagement pressure command value can be fixed to an appropriate engagement pressure command value according to the direction in which the engine output torque changes.

According to the fifth aspect of the invention, in both the drive state and the coast state, the slip lock-up control for bringing the slip rotation speed close to the target can be performed by the same processing, and the drive state and the coast state can be controlled. Even if the absolute value of the engine output torque fluctuates greatly during switching between the two modes, the engagement pressure can be controlled without being affected by this, and the stability of the slip lock-up control can be improved. There is.

[0019]

Embodiments of the present invention will be described below. FIG. 1 is a system configuration diagram of a vehicle automatic transmission according to an embodiment. In FIG. 1, an engine 1
, The gear type transmission 3 is connected via the torque converter 2. The transmission 3 may be a belt-type or toroidal-type continuously variable transmission (CVT).

The torque converter 2 is provided with a lock-up clutch 21 for mechanically directly connecting the input shaft and the output shaft, and is supplied to the release side of the lock-up clutch 21 by a lock-up hydraulic control valve 22. The hydraulic pressure and the hydraulic pressure supplied to the engagement side are controlled. A transmission control unit 31 that controls the lock-up hydraulic control valve 22 includes a throttle sensor 13 that detects an opening TVO of a throttle valve 12 interposed in the intake pipe 11 of the engine 1 and a rotation speed Ne of the engine 1. An engine speed sensor 32 for detecting, a turbine speed sensor 3 for detecting a turbine speed ωtr of the torque converter 2
3. a vehicle speed sensor 34 for detecting the running speed (vehicle speed) VSP of the vehicle, an oil temperature sensor 35 for detecting the temperature Tatf of the automatic transmission fluid (ATF),
Detection signals from an impeller rotation speed sensor 36 for detecting the impeller rotation speed ωir of the torque converter 2 are input, and based on these detection signals, the lock-up hydraulic control valve 22 is controlled and the gear type transmission 3 is controlled. The shift valve that controls the supply of the hydraulic pressure to the various friction engagement elements that are configured is controlled.

The transmission control unit 31 controls the transmission valve in accordance with a shift schedule preset according to the throttle opening TVO (accelerator opening) and the vehicle speed VSP, while controlling the throttle opening TVO (accelerator opening). Degree) and the vehicle speed VSP, the locking is performed such that the difference (slip rotation speed) between the rotation speed of the input shaft and the rotation speed of the output shaft of the torque converter 2 becomes a target value in a slip lock-up control region set in advance. The up hydraulic control valve 22 is controlled.

The slip lock-up control by the transmission control unit 31 is performed by the arithmetic processing shown in the control block diagram of FIG. In FIG. 2, the target slip rotation calculation unit 101 includes a vehicle speed VSP and a throttle opening TV.
The target slip rotation speed Tslip is determined based on O, the gear ratio, and the oil temperature Tatf, and the absolute value of the target slip rotation Tslip |
Tslip | is output to the slip rotation deviation calculation unit 103.

The actual slip rotation calculation unit 102 subtracts the turbine rotation speed ωtr corresponding to the output shaft rotation speed from the impeller rotation speed ωir corresponding to the input shaft rotation speed of the torque converter 2, and calculates the actual slip rotation of the torque converter 2. The rotation speed Slip is calculated, and the absolute value | Slip | of the actual slip rotation speed Slip is calculated by the slip rotation deviation calculation unit 103.
Output to

In the slip rotation deviation calculator 103,
A slip rotation deviation Eslip which is a deviation between the absolute value | Tslip | of the target slip rotation speed Tslip and the absolute value | Slip | of the actual slip rotation speed Slip is calculated. Eslip = | Tslip |-| Slip | In the slip rotation command value calculation unit 104, for example, a well-known proportional (P) / integration (I) based on the slip rotation deviation Eslip.
The actual slip rotation speed | Slip | is reduced to the target slip rotation speed | Tsli by eliminating the slip rotation deviation Eslip by the operation.
The slip rotation command value Scnv for making it coincide with p | is calculated.

The slip rotation gain calculator 105 sets a slip rotation gain Cg from the turbine rotation speed ωtr. The target converter torque calculation unit 106 calculates a converter torque Tcnv to be a target for achieving the slip rotation command value Scnv based on the slip rotation gain Cg and the turbine rotation speed ωtr at that time.

The engine output torque estimating section 107 obtains an estimated value Te of the engine output torque from the engine speed Ne and the throttle opening TVO, and outputs an absolute value | Te | of the estimated value Te. In estimating the engine output torque based on the engine rotation speed Ne and the throttle opening TVO, the delay is set so as to correspond to a response delay of the actual engine output torque to a change in the engine rotation speed Ne and / or the throttle opening TVO. It is preferable to perform a filter process corresponding to the characteristics.

The target lock-up clutch engagement capacity calculation unit 108 calculates the absolute value | Te | of the engine output torque Te.
Is subtracted from the target converter torque Tcnv to obtain the target lock-up clutch engagement capacity Tlu. Tlu = | Te | -Tcnv In the lock-up clutch engagement pressure command value calculation unit 109,
A lock-up clutch engagement pressure command value Plu for achieving the target lock-up clutch engagement capacity Tlu is calculated.

The drive signal calculating section 110 determines a drive signal Dlu for setting the actual lock-up clutch engagement pressure to the lock-up clutch engagement pressure command value Plu, and outputs this to the lock-up hydraulic control valve 22. As described above, if the configuration is such that the engagement pressure command value Plu of the lock-up hydraulic control valve 22 is calculated based on the absolute values of the actual slip rotation speed Slip, the target slip rotation speed Tslip, and the engine output torque Te, respectively. Even in the coast state, the slip lock-up control can be performed.

When the absolute value is not used as described above, the turbine rotation speed of the torque converter 2 becomes higher than the impeller rotation speed in the coast state, and the actual slip rotation speed Slip becomes a negative value or the target slip rotation speed Slip becomes negative. If a negative value is set as the speed Tslip, or if the engine output torque becomes negative during the coast, if the control is performed in the normal state, the deviation will be further increased and it will not be possible to converge to the target. (See FIG. 6).

On the other hand, if the absolute values of the actual slip rotation speed Slip, the target slip rotation speed Tslip, and the engine output torque Te are used as described above, even if these are calculated to be negative values, By controlling the engagement pressure in the normal calculation, control can be performed to approach the target (see FIG. 3). However, when switching from the drive state to the coast state, or when switching from the coast state to the drive state, the engine output torque changes from plus to minus or from minus to plus, and its absolute value decreases rapidly. After the value becomes 0, it shows a rapidly increasing change. If the engagement pressure is determined by using the absolute value of the engine output torque, the engagement pressure will suddenly change and the drivability will be deteriorated.

Therefore, in the present embodiment, as shown in FIG. 2, when switching from the drive state to the coast state,
Alternatively, a configuration is provided for performing a process of fixing the fastening pressure to a preset value when switching from the coast state to the drive state. The drive / coast determination unit 111 determines whether the vehicle is in the drive state or the coast state based on the throttle opening TVO.

The timer section 112 counts whether or not within a predetermined time after switching from the drive state to the coast state, or from the coast state to the drive state, based on the determination result of the drive / coast determination section 111. . Then, when it is within a predetermined time after switching from the drive state to the coast state or from the coast state to the drive state based on the measurement by the timer unit 112,
The engagement pressure fixing unit 113 causes the lock-up clutch engagement pressure command value calculation unit 109 to output a value set in advance as the lock-up clutch engagement pressure command value.

In parallel with the fixing of the engagement pressure command value, the feedback stop unit 114 stops the feedback operation in the slip rotation command value calculation unit 104. The details of the processing by the drive / coast determination unit 111, the timer unit 112, the fastening pressure fixing unit 113, and the feedback stop unit 114 are shown in the flowchart of FIG.

In the flowchart of FIG. 4, in step S1, it is determined whether or not the slip lock-up control is being performed. Note that the slip lock-up control region is set in advance according to the throttle opening (accelerator opening) and the vehicle speed. If the slip lock-up control is being performed, the process proceeds to step S2, and it is determined whether the vehicle is in the drive state or the coast state.

In the determination of the drive coast state, a state in which the throttle opening is equal to or less than a predetermined opening is determined to be a coast state, and when the throttle opening exceeds the predetermined opening, the drive state is determined. In step S3, it is determined whether or not the drive state has been switched to the coast state based on the determination result in step S2. Specifically, it is determined that the drive state has been switched to the coast state when it is determined that the current state is the coast state while the drive state was previously determined to be the drive state.

If it is determined in step S3 that the state has been switched from the drive state to the coast state, the process proceeds to step S4, and 1 is set in the flag F. On the other hand, if it is determined in step S3 that it is not the timing to switch from the drive state to the coast state, the process proceeds to step S5, and similarly, it is determined whether or not the switch has been made from the coast state to the drive state.

When it is determined in step S5 that the state has been switched from the coast state to the drive state, the process proceeds to step S6, and the flag F is set to 2. In step S7, it is determined whether or not the flag F is 1, and if the flag F = 1, the process proceeds to step S8. Step S
In step S8, the timer DCTMR is incremented by one, and in step S9, it is determined whether or not the timer DCTMR has exceeded a preset determination value DCTIM.

Since the routine shown in the flowchart of FIG. 4 is executed at predetermined time intervals, it is determined whether or not the timer DCTMR has exceeded the determination value DCTIM.
This corresponds to determining whether or not a predetermined time has elapsed after switching from the drive state to the coast state or from the drive state to the coast state. Until the timer DCTMR exceeds the determination value DCTIM, step S
10, the lock-up clutch engagement pressure command value P
lu is set to a value INITPRSDC preset as a value suitable for the coast slip lockup state.

That is, when it is within a predetermined time (DCTIM) after switching from the drive state to the coast state,
The setting of the engagement pressure command value Plu based on the actual slip rotation speed and the engine output torque is canceled, and the engagement pressure command value Plu is canceled.
Is fixed to the set value INITPRSDC. Step S
At 11, the feedback operation in the slip rotation command value calculation unit 104 is stopped.

Thus, if within a predetermined time (DCTIM) after switching from the drive state to the coast state, even if there is a deviation between the actual slip rotation speed and the target slip rotation speed, the deviation is integrated by the integration operation. Never be. In step S9, the timer DCTMR
Is determined to have exceeded the determination value DCTIM, step S1
7, the flag F is reset to zero,
The process of fixing the engagement pressure command value Plu to the set value INITPRSDC is stopped, and the process returns to the engagement pressure command value Plu set to obtain a normal target slip rotation speed.

If it is determined in step S7 that the flag F is not 1, the process proceeds to step S12, where the flag F = 2.
Is determined. In step S12, the flag F =
If it is determined to be 2, the process proceeds to steps S13 to S16, and, similarly to steps S8 to S11, a predetermined time (DCTIM) after switching from the coast state to the drive state.
If it is within the range, the setting of the engagement pressure command value Plu based on the actual slip rotation speed and the engine output torque is canceled, and the engagement pressure command value Plu is fixed to the set value INITPRSCD.

Here, the set value INITPRSCD is a value set in advance as a value suitable for the drive slip lockup state, and is a timing for switching from the coast state to the drive state, or switching from the drive state to the coast state. The engagement pressure command value Plu is fixed to a different value depending on whether the timing is the switching timing. Step S10
Alternatively, in step S15, when a fixed value is set to the engagement pressure command value Plu and the process proceeds to the slip lock-up control in step S19, the engagement pressure command value Plu = INITPRSDC, INITP
The RSCD is converted into a drive signal Dlu, which is output to the lock-up hydraulic control valve 22.

On the other hand, if it is determined in step S12 that the flag F is not equal to 2, it is determined that the state is not immediately after switching from the coast state to the drive state or from the drive state to the coast state. After resetting the DCTMR to zero, the process proceeds to step S19 without setting a fixed value to the engagement pressure command value Plu, and performs a slip lockup control based on the engagement pressure command value Plu set to the target slip rotation speed. Let

As described above, if the engagement pressure command value Plu is fixed for a predetermined time immediately after switching from the coast state to the drive state, or from the drive state to the coast state, the coast state can be changed to the drive state. Even if the absolute value of the engine output torque suddenly changes greatly from the state to the coast state, the engagement force of the lock-up clutch does not fluctuate due to the sudden change and the drivability can be prevented from deteriorating. 5).

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of an automatic transmission according to an embodiment.

FIG. 2 is a functional block diagram of slip lock-up control in the embodiment.

FIG. 3 is a time chart showing characteristics in a case where absolute values of a slip rotation speed, a target slip rotation speed, and an output torque of an engine are used for calculating a fastening pressure command value.

FIG. 4 is a flowchart showing control for fixing an engagement pressure command value at the time of drive / coast switching.

FIG. 5 is a time chart showing characteristics when an engagement pressure command value is fixed at the time of drive / coast switching.

FIG. 6 is a time chart showing a problem of conventional control.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Torque converter 3 ... Gear type transmission 12 ... Throttle valve 13 ... Throttle sensor 21 ... Lockup clutch 22 ... Lockup hydraulic control valve 31 ... Transmission control unit 32 ... Engine rotation speed sensor 33 ... Turbine rotation speed Sensor 34: Vehicle speed sensor 35: Oil temperature sensor 36: Impeller rotation speed sensor

Claims (5)

[Claims] An input shaft and an output shaft of a torque converter interposed between an engine and a transmission; and a lock-up clutch for mechanically directly connecting an input shaft and an output shaft. An automatic transmission configured to detect a certain slip rotation speed, and determine an engagement pressure command value of the lock-up clutch based on a deviation between the detected slip rotation speed and a target slip rotation speed and an engine output torque. Wherein the engagement pressure command value is determined based on an absolute value of each of the slip rotation speed, the target slip rotation speed, and the output torque of the engine. Lock-up control device. 2. A lock-up clutch mechanically directly connecting an input shaft and an output shaft of a torque converter interposed between an engine and a transmission, wherein a lock-up clutch is provided for detecting a rotational speed difference between the input shaft and the output shaft. An automatic transmission configured to detect a certain slip rotation speed, and determine an engagement pressure command value of the lock-up clutch based on a deviation between the detected slip rotation speed and a target slip rotation speed and an engine output torque. Wherein the engagement pressure command value is fixed at a preset value for a preset time when switching between the drive state and the coast state. Machine lock control device. 3. The automatic automatic transmission system according to claim 2, wherein said engagement pressure command value is fixed at a preset value for said preset time, and a feedback operation for eliminating said deviation is stopped. Transmission slip lock-up control device. 4. The fastening pressure command value is fixed to a different value depending on whether the state is switched from the drive state to the coast state or the state is switched from the coast state to the drive state. The slip lock-up control device for an automatic transmission according to claim 2 or 3. 5. The engagement pressure command value is determined based on an absolute value of each of the slip rotation speed, a target slip rotation speed, and an output torque of an engine. The slip lock-up control device for an automatic transmission according to claim 1.