JP2008008321A - Lock-up control device for torque converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To set a lock-up capacity during coast traveling in a lock-up mode to quickly release a lock-up clutch during abruptly braking a vehicle while preventing the disengagement of the clutch. <P>SOLUTION: When coast traveling is achieved during fastening the lock-up clutch, a lock-up capacity is reduced so that a slip rotating speed is a predetermined low rotating speed (S10). The lock-up capacity with the slip rotating speed being the predetermined low rotating speed is set as a learning value (S21). During a time after the slip rotating speed is the predetermined low rotating speed and before a predetermined time passes, deviation between the predetermined low rotating speed and an actual slip rotating speed is integrated (S24). The learning value is corrected in accordance with an integrated value for the deviation (S28). A minimum lock-up capacity is set to be the corrected learning value (S29). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a lockup control device for a torque converter.

  The lock-up control device for the torque converter inserted in the driving force transmission system of the automatic transmission including the continuously variable transmission is used to increase the torque and reduce the fuel consumption caused by the slip of the torque converter. In an operation region that does not require the shock absorbing function, the input / output elements of the torque converter are directly connected using a lock-up clutch. This is called the lock-up mode. In addition to this, the converter mode that completely releases the input / output elements and transmits torque via the fluid, and the slip that keeps the lock-up clutch in the semi-engaged state and maintains the predetermined slip state. There are three modes, which can be switched appropriately according to the driving state of the vehicle. This mode switching is performed by changing the lockup differential pressure, and the converter mode is set for the minimum pressure and the lockup mode is set for the maximum pressure.

  Fuel consumption is improved by performing fuel cut when the vehicle is in the lockup mode and coasting. However, since the engine is being driven by the drive wheels at this time, the vehicle is quickly driven when the vehicle is suddenly braked. If the lockup clutch is not released, the engine speed may decrease as the vehicle speed (primary rotation speed) decreases, and engine stall may occur.

Therefore, Patent Document 1 discloses a technique for improving the clutch release responsiveness during sudden braking by reducing the clutch capacity during coasting in advance. In other words, the clutch capacity when a predetermined slip rotation occurs during coasting is set as a learned value, and the capacity obtained by adding the predetermined value to the learned value is set as the previously-decreased clutch capacity. As a result, the lockup capacity is reduced as compared with the normal lockup mode, and the lockup clutch is quickly released when the vehicle is suddenly braked.
Japanese Patent Laid-Open No. 10-299887

  However, in the above conventional technique, when the slip rotation reaches the predetermined rotation, the clutch capacity at that time is used as the learning value. However, when the slip rotation accidentally reaches the predetermined rotation due to an external factor, the learning value is also set. Is done.

  As a result, when the capacity obtained by adding the predetermined value to the learning value is larger than the value that should be calculated, it takes more time to release the lockup clutch when the vehicle is suddenly braked. It can happen.

  When the capacity obtained by adding the predetermined value to the learning value is smaller than the value that should be calculated, the lockup clutch is easily released, and the fuel cut is stopped by the release, so that the fuel consumption is deteriorated.

  An object of the present invention is to set the lockup capacity during coasting in the lockup mode so that the lockup clutch can be quickly released during sudden braking of the vehicle while preventing the clutch from being disengaged.

  The present invention relates to a lockup clutch that can be directly connected by fastening between an input element and an output element of a torque converter, and an engagement capacity of the lockup clutch when the vehicle is coasted while the lockup clutch is engaged. And a lockup capacity control means for controlling the lockup capacity to be a minimum lockup capacity that is a minimum lockup capacity that does not cause a slip between an input element and an output element of the lockup clutch. In the lockup control device of the converter, when the vehicle starts coasting while the lockup clutch is engaged, the slip rotation speed, which is the rotation speed difference between the input element and the output element, becomes a predetermined low rotation speed. The lockup capacity lowering means for lowering the lockup capacity and the slip rotation speed to a predetermined value. Learning value setting means for setting the lock-up capacity at the rotational speed as a learned value, and the predetermined low rotational speed and the actual time from when the slip rotational speed reaches the predetermined low rotational speed until a predetermined time elapses. Learning value correction means that corrects the learning value based on the value obtained by integrating the deviation, and the minimum lock that sets the minimum lockup capacity to the learning value corrected by the learning value correction means Up capacity setting means.

  According to the present invention, when the vehicle is coasted while the lockup clutch is engaged, the lockup clutch is slipped for a predetermined time, and the minimum lockup capacity is set according to the slip state during the predetermined time. The lock-up clutch can be accurately set to the minimum lock-up capacity at which the lock-up clutch does not slip, and the lock-up clutch can be quickly released during sudden braking of the vehicle while preventing the clutch from being disengaged.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram of a lockup control device for a torque converter according to the present invention.

  The torque converter 1 is interposed between the engine 14 and the transmission 15 and transmits the driving force of the engine 14 to the transmission 15 via a fluid. The transmission 15 is an automatic transmission, and the driving force transmitted to the transmission 15 is transmitted to the drive wheels 16 via a final reduction gear (not shown).

  In the torque converter 1, a pump impeller 12 connected to the output shaft of the engine 14 and a turbine runner 13 connected to the input shaft of the transmission 15 are arranged to face each other. When the pump impeller 12 rotates with the rotation of the engine 14, the fluid (ATF) filled in the torque converter 1 flows, whereby the turbine runner 13 rotates. The torque converter 1 further includes a lockup clutch 2 that rotates together with the turbine runner 13.

  When the lockup clutch 2 is fastened to the pump impeller 12, the torque converter 1 is directly connected to the input element and the output element of the torque converter and enters a lockup state. In addition, when the input element and the output element are in a semi-fastened state, a slip state occurs in which slip occurs between the input element and the output element. When the lockup clutch 2 is completely released, the converter state is established.

  The lockup clutch 2 corresponds to a differential pressure ΔP (= PA−PR) between a torque converter apply pressure PA (hereinafter referred to as “apply pressure PA”) and a torque converter release pressure PR (hereinafter referred to as “release pressure PR”) acting on both sides thereof. Operate. The lockup clutch 2 is released when the release pressure PR is higher than the apply pressure PA, and is engaged when the release pressure PR is lower than the apply pressure PA.

  The torque that can be transmitted by the lockup clutch of the torque converter that depends on the fastening force of the lockup clutch 2, that is, the lockup capacity, is determined by the differential pressure ΔP. As the differential pressure ΔP increases, the fastening force of the lockup clutch 2 increases and the lockup capacity increases. The differential pressure ΔP is controlled by the lockup control valve 3.

  The lockup control valve 3 controls the differential pressure ΔP by controlling the apply pressure and the release pressure that act on the lockup clutch 2. The lockup control valve 3 is applied with the apply pressure PA and the release pressure PR facing each other, and further, the urging force of the spring 3a is applied in the same direction as the apply pressure PA, and from the lockup solenoid 4 in the same direction as the release pressure PR. The supplied signal pressure PS is applied. The differential pressure ΔP is determined so that the hydraulic pressure and the biasing force of the spring are balanced.

  The lockup solenoid 4 generates a signal pressure PS in accordance with the lockup duty D transmitted from the controller 5 with the pump pressure PP as an original pressure.

  A power supply voltage sensor 6 for detecting the power supply voltage, a pump impeller rotation sensor 7 for detecting the rotation speed of the pump impeller 12, a turbine runner rotation sensor 8 for detecting the rotation speed of the turbine runner 13, and an output shaft rotation speed of the transmission 15 are detected. The transmission output shaft rotation sensor 9 that performs the detection, the throttle opening sensor 10 that detects the throttle opening, and the ATF temperature sensor 11 that detects the temperature of the ATF transmit the detected values to the controller 5.

  The controller 5 determines the drive duty D of the lockup solenoid 4 and controls the lockup duty D according to the power supply voltage signal in order to control the engagement state of the lockup clutch 2 based on the received signal. .

  Next, the control performed by the controller 5 will be described with reference to FIG. FIG. 2 is a flowchart showing the control of the torque converter lockup control device according to the present invention. This control is repeatedly performed every minute time (for example, 10 ms).

  In step S1, it is determined whether or not the operation mode is step = 0. If the operation mode is step = 0, the process proceeds to step S2, and if other than step = 0, the process proceeds to step S5. The operation mode step = 0 indicates an operation mode in which the vehicle is in the complete lockup state and the vehicle is not in the coasting state.

  In step S2, it is determined whether or not the lockup clutch 2 is in the lockup mode, that is, the complete lockup state. If it is in the complete lockup state, the process proceeds to step S3.

  In step S3, it is determined whether or not the vehicle is running on the coast. If coasting is in progress, the process proceeds to step S4. If coasting is not in progress, the process returns.

  In step S4, the operation mode is set to step = 1, and the process returns. The operation mode step = 1 indicates that the vehicle is in the complete lockup state, the vehicle is in the coasting state, and the coast lockup control is operating. The coast lock-up control is a control that improves the responsiveness of clutch release during sudden braking by reducing the clutch capacity during coasting in advance.

  On the other hand, if it is determined in step S1 that the operation mode is other than step = 0, the process proceeds to step S5, in which it is determined whether or not the vehicle is coasting. If coasting is in progress, the process proceeds to step S6, and if not coasting, the process proceeds to step S31.

  In step S6, it is determined whether or not the operation mode is step = 1. If the operation mode is step = 1, the process proceeds to step S7, and if other than step = 1, the process proceeds to step S11.

  In step S7, it is determined whether or not the rotational speed Ne (engine rotational speed) of the pump impeller 12 is lower than a predetermined rotational speed NEINH. If the rotational speed Ne of the pump impeller 12 is lower than the predetermined rotational speed NEINH, the process proceeds to step S8, and if the rotational speed NeIN is higher than the predetermined rotational speed NEINH, the process returns.

  In step S8, it is determined whether or not the vehicle speed Vsp is lower than a predetermined vehicle speed VSPINH. If the vehicle speed Vsp is lower than the predetermined vehicle speed VSPINH, the process proceeds to step S9. If the vehicle speed Vsp is equal to or higher than the predetermined vehicle speed VSPINH, the process returns.

  In step S9, the operation mode is set to step = 2. The operation mode step = 2 indicates that the pressure reduction control of the lockup capacity PLU during coasting is in operation.

  In step S10 (lockup capacity lowering means), the lockup capacity PLU is reduced to the engagement capacity PLO obtained by adding the set capacity ΔP to the learning value PLRN at the previous processing, and then the pressure reduction control is started. The decompression control is control for reducing the lockup capacity PLU to a lockup capacity close to the minimum lockup state in which no slip occurs in the lockup clutch.

  On the other hand, if it is determined in step S6 that the operation mode is other than step = 1, the process proceeds to step S11 to determine whether or not the operation mode is step = 2. If the operation mode is step = 2, the process proceeds to step S12. If the operation mode is other than step = 2, the process proceeds to step S17.

  In step S12, it is determined whether or not the slip rotation speed Slp is greater than the first slip rotation speed SLPINH1. If the slip rotation speed Slp is greater than the first slip rotation speed SLPINH1, the process proceeds to step S13, and if it is equal to or less than the first slip rotation speed SLPINH1, the process proceeds to step S16.

  The slip rotation speed Slp is calculated by subtracting the rotation speed of the turbine runner 13 from the rotation speed of the pump impeller 12, and if the lock-up capacity PLU is decreased during coasting, the slip rotation speed Slp is a negative value. It becomes.

  Here, since the friction coefficient varies due to individual differences, temperature differences, and secular changes, the lock-up clutch 2 may be released when the pressure-reducing control is performed in step S10. Therefore, in step S12, an abnormal slip state in which the slip rotation speed Slp is equal to or lower than the first slip rotation speed SLPINH1 is determined.

  In step S13, it is determined whether the pressure reduction control is complete. If the pressure reduction control has been completed, the process proceeds to step S14, and if not completed, the process returns. When the lockup capacity PLU decreases to a lockup capacity close to the minimum lockup state, it is determined that the pressure reduction control is completed.

  On the other hand, when it is determined in step S12 that the slip rotation speed Slp is equal to or less than the first slip rotation speed SLPINH1, the process proceeds to step S16, and the lockup capacity PLU is increased by a predetermined capacity Pup1. Thereby, it is possible to prevent the lockup clutch 2 from being released due to the lockup capacity PLU being excessively reduced by the pressure reduction control in step S10.

  In step S14, the operation mode is set to step = 3. The operation mode step = 3 indicates that the pressure reduction control of the lockup capacity PLU has been completed and the slip start capacity at which a minute target slip is being detected is being detected.

  In step S15, the target slip rotation control is started so that the lockup capacity PLU is controlled and the slip rotation speed Slp becomes the target slip rotation speed. The target slip rotation speed is set so that the slip rotation speed Slp generated between the input / output elements of the torque converter 1 becomes minute. In the target slip rotation control, for example, proportional / integral (PI) control is performed according to the following equations (1) and (2).

  Here, Err is a slip rotation deviation, SLPTGT is a target slip rotation speed, Slp is an actual slip rotation speed, Kp is a proportional gain, Ki is an integral gain, and s is a differential operator.

  On the other hand, if it is determined in step S11 that the operation mode is other than step = 2, the routine proceeds to step S17, where it is determined whether or not the slip rotation speed Slp is greater than the second slip rotation speed SLPINH2. If the slip rotation speed Slp is greater than the second slip rotation speed SLPINH2, the process proceeds to step S18, and if it is equal to or less than the second slip rotation speed SLPINH2, the process proceeds to step S30 and the target slip rotation control is stopped.

  In step S18, it is determined whether or not the operation mode is step = 3. If the operation mode is step = 3, the process proceeds to step S19, and if other than step = 3, the process proceeds to step S23.

  In step S19, it is determined whether or not a learning condition is satisfied. If the learning condition is satisfied, the process proceeds to step S20, and if not satisfied, the process returns. The learning condition is satisfied when the slip rotation speed Slp remains within a predetermined rotation speed region for a predetermined time. The learning condition is not limited to this. For example, the slip rotation speed Slp may be equal to the target slip rotation speed SLPTGT, or the slip rotation speed Slp may be maintained below the target slip rotation speed SLPTGT for a predetermined time.

  In step S20, the operation mode is set to step = 4. The operation mode step = 4 indicates that the slip control is continued after the target slip is detected, and the slip rotation deviation Err is being integrated. Here, the lockup capacity PLU at this point is the new slip start capacity PLS.

  In step S21 (learning value setting means), a new slip start capacity PLS is recorded as a learning value candidate PLRNetr.

  In step S22, evaluation of the learning value PLRN is started. The learning value evaluation is continued for a predetermined time.

  On the other hand, if it is determined in step S18 that the operation mode is other than step = 3, the process proceeds to step S23 to determine whether or not the operation mode is step = 4. If the operation mode is step = 4, the process proceeds to step S24, and if other than step = 4, the process returns.

  In step S24, the slip rotation deviation Err is integrated.

  In step S25, it is determined whether or not a predetermined evaluation time TM has elapsed since the learning value evaluation was started in step S22. If the predetermined evaluation time TM has elapsed, the process proceeds to step S26, and if not, the process returns.

  In step S26, the operation mode is set to step = 5. The operation mode step = 5 indicates that the learning value PLRN including the correction value ΔPLRNNadj is calculated based on the accumulated slip rotation deviation Err, and that the learning value PLRN is increased by a predetermined capacity and the minimum lockup is performed.

  In step S27, a correction value ΔPLRNNadj is calculated based on the integrated value ΣErr of the slip rotation deviation Err. The correction value ΔPLRNNadj calculates the slip rotation deviation SErrT per unit time by dividing the integrated value ΣErr of the slip rotation deviation Err by the evaluation time TM after starting the learning value evaluation, and refers to the table of FIG. Is calculated based on the slip rotation deviation SErrT per unit time.

  In step S28 (learning value correcting means), the learning value PLRN is updated. The update method will be described later.

  In step S29 (minimum lockup capacity setting means), the minimum lockup engagement capacity PLUmin is calculated, and the lockup capacity is set to the minimum lockup engagement capacity PLUmin. The minimum lock-up engagement capacity PLUmin is a minimum lock-up engagement capacity that does not cause a slip between input and output elements of the torque converter 1, and is calculated by adding a predetermined capacity α to the updated learning value PLRN.

  On the other hand, if it is determined in step S5 that the vehicle is not coasting, the process proceeds to step S31 to stop coast control, and it is determined whether or not the operation mode is step = 3. If the operation mode is step = 3, the process proceeds to step S32, and if other than step = 3, the process proceeds to step S35.

  In step S32, it is determined whether or not the current lockup capacity PLU is smaller than the learning value PLRN at the previous processing. If the current lockup capacity PLU is smaller than the learning value PLRN at the previous processing, the process proceeds to step S33, and if it is greater than the learning value at the previous processing, the process proceeds to step S38.

  In step S33 (learning value setting means), the current lockup capacity PLU is set as a learning value candidate PLRNetr. As a result, the learning value candidate PLRNetr can be obtained even when coast control is stopped, and the frequency of learning can be increased.

  In step S34, the correction value ΔPLRNAd is set to zero. Here, since the value determined as the learning value candidate PLRNetr in step S33 is not a value set by detecting the slip rotation speed Slp, the correction value ΔPLRNNadj is set to zero.

  On the other hand, if it is determined in step S31 that the operation mode is other than step = 3, the process proceeds to step S35 to determine whether or not the operation mode is step = 4. If the operation mode is step = 4, the process proceeds to step S36, and if other than step = 4, the process proceeds to step S38.

  In step S36, the correction value ΔPLRNAd of the learning value PLRN is calculated based on the integrated value ΣErr of the slip rotation deviation Err. The calculation method of the correction value ΔPLRNNadj is the same as that in step S27. This step is executed when the coast lockup control is interrupted during the evaluation of the learning value candidate PLRNetr by integrating the slip rotation deviation Err. In this case, since the learning value candidate PLRNetr has already been determined, the correction value Only ΔPLRNadj is calculated.

  In step S37 (learning value correcting means), the learning value PLRN is updated. The update method will be described later.

  In step S38, the coast lockup control is initialized.

  In step S39, the operation mode is set to step = 0.

  Next, a method for updating the learning value PLRN in steps S28 and S37 will be described. The learning value candidate PLRNetr set in steps S21 and S33 and the correction value ΔPLRNNaj calculated in steps S27, S34 and S36 are stored in the FIFO buffer (corrected learning value storage means) shown in FIG. 4 in steps S28 and S37. Is done.

  Here, the FIFO buffer is a first-in / first-out buffer. When the number of stored data is less than the buffer size, all input data is stored in the buffer, and when the number of stored data exceeds the buffer size, it is exceeded. The old data is sequentially discarded by the amount and new data is stored.

  After storing the learning value candidate PLRNetr and the correction value ΔPLRNNadj, the maximum value and the minimum value are removed from the addition values of the candidate value and the correction value ΔPLRNNadj at the same learning timing. The learning value PLRN is updated by calculating the average value of the remaining data. That is, the learning value PLRN is calculated according to the following equation (3).

Here, n is a buffer size, CLP _i is a learning value candidate (i = 1 to n), and OFS _i is a correction value (i = 1 to n).

  Next, the operation of this embodiment will be described with reference to FIG. FIG. 5 is a time chart showing the operation of the torque converter control device according to this embodiment. (A) is a lockup capacity, (b) is a slip rotation speed, (c) is an integrated slip deviation value, and (d) is (E) is a correction value, (f) is a learning value, (g) is a learning end, (h) is an evaluation end, (i) is an engine speed and a primary speed, (j) is a vehicle speed, (K) indicates the throttle opening, and (l) indicates the operation mode.

  While the vehicle is traveling with the lock-up clutch 2 engaged, the throttle opening becomes zero at time t1 and the coasting state is set, and the operation mode becomes step = 1.

  At time t2, when the engine rotational speed Ne falls below the predetermined rotational speed NEINH and the vehicle speed falls below the predetermined vehicle speed VSPINH, the lockup capacity PLU is reduced to the fastening capacity PLO, and pressure reduction control is started, and the operation mode is step = 2.

  At time t3, when it is determined that the lockup capacity PLU has decreased to the slip start capacity and the pressure reduction control has been completed, the slip control is started and the operation mode becomes step = 3.

  When the state where the slip rotation speed Slp is within the predetermined rotation speed region with the target slip rotation speed as the center continues for a predetermined time, the learning condition is satisfied at time t4, the learning value candidate PLRNetr is recorded, and the slip rotation deviation Err is integrated. And the operation mode becomes step = 4.

  When a predetermined evaluation time TM has elapsed since the learning value candidate PLRNNet has been recorded, a correction value ΔPLRNNadj corresponding to the slip rotation deviation Err is set at time t5, and the correction value is added to the learning value candidate PLRNNet to learn value PLRN. And the operation mode becomes step = 5. The vehicle travels in the minimum lock-up state with the value obtained by increasing the learning value PLRN by the predetermined capacity α as a lock-up capacity.

  As described above, in this embodiment, when the vehicle is coasted while the lockup clutch 2 is engaged, the lockup clutch 2 is slipped by performing pressure reduction control, and the lockup capacity at this time is determined as a learning value candidate. The correction value is calculated according to the integrated value of the slip rotation deviation during a predetermined evaluation time, and the minimum lockup fastening capacity as the learning value is calculated by adding the correction value to the learning value candidate. The minimum lock-up capacity at which the clutch 2 does not slip can be accurately calculated, and the lock-up clutch 2 can be released promptly during sudden braking of the vehicle while preventing clutch disengagement.

  Also, the integrated value of slip rotation deviation during a predetermined evaluation time is divided by the predetermined evaluation time to calculate the slip rotation deviation per unit time, and the correction value is calculated based on the slip rotation deviation per unit time. Uniform correction can be performed regardless of the length of time, and the lock-up clutch 2 can be quickly released during sudden braking of the vehicle while more reliably preventing clutch disengagement.

  Further, when the integrated value of the slip rotation deviation is positive, the actual slip rotation speed Slp is lower than the target slip rotation speed, that is, the lock-up clutch is slippery, so a positive value is set as the correction value. Thus, learning value candidates can be positively corrected to prevent clutch disengagement during coast lockup control. When the integrated value of the slip rotation deviation is negative, the actual slip rotation speed Slp exceeds the target slip rotation speed, that is, the lock-up clutch seems to be engaged, so the correction value is set to zero and the learning candidate value is not corrected. As a result, clutch disengagement during coast lockup control can be prevented.

  Further, the learning value candidate and the correction value are stored in the FIFO buffer, and the average value of the stored data is used as the learning value, so that the influence of the error can be removed and the learning value can be calculated more accurately. .

  Further, the learning value candidate and the correction value are stored in the FIFO buffer, and the average value is calculated from the stored data after removing the maximum value and the minimum value, and the learning value is calculated. The value can be removed, and the learning value can be calculated more accurately.

  The present invention is not limited to the embodiment described above, and various modifications and changes can be made within the scope of the technical idea.

It is a schematic block diagram which shows the lockup control apparatus of the torque converter in this embodiment. It is a flowchart which shows control of the lockup control apparatus of the torque converter in this embodiment. 10 is a table showing a relationship between a slip rotation deviation SErrT per unit time and a correction value ΔPLRNNadj. It is explanatory drawing which shows the effect | action of a FIFO buffer. It is a time chart which shows the effect | action of the lockup control apparatus of the torque converter in this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Torque converter 2 Lockup clutch 3 Lockup control valve 3a Spring 4 Lockup solenoid 5 Controller 6 Power supply voltage sensor 7 Pump impeller rotation sensor 8 Turbine runner rotation sensor 9 Transmission output shaft rotation sensor 10 Throttle rotation sensor 11 ATF temperature sensor 12 Pump impeller 13 Turbine runner 14 Engine 15 Transmission 16 Drive wheel

Claims (5)

A lock-up clutch that can be directly connected by fastening between an input element and an output element of the torque converter;
When the vehicle is coasted while the lock-up clutch is engaged, the lock-up capacity, which is the engagement capacity of the lock-up clutch, is the minimum that does not cause a slip between the input element and the output element of the lock-up clutch. Lockup capacity control means for controlling the lockup capacity to be the minimum lockup capacity,
In a torque converter lockup control device comprising:
When the vehicle starts coasting while the lockup clutch is engaged, the lockup capacity is set so that the slip rotation speed, which is the rotation speed difference between the input element and the output element, becomes a predetermined low rotation speed. Means for lowering the lockup capacity to be reduced;
Learning value setting means for setting a lockup capacity when the slip rotation speed becomes the predetermined low rotation speed as a learning value;
Based on the value obtained by integrating the deviation between the predetermined low rotational speed and the actual slip rotational speed until the predetermined time elapses after the slip rotational speed becomes the predetermined low rotational speed. Learning value correcting means for correcting the learning value;
Minimum lockup capacity setting means for setting the minimum lockup capacity to the learning value corrected by the learning value correction means;
A lockup control device for a torque converter, comprising:   2. The lockup control device for a torque converter according to claim 1, wherein the learning value correction unit corrects the learning value based on a value obtained by dividing the value obtained by integrating the deviation by the predetermined time.   3. The lockup control device for a torque converter according to claim 1, wherein the learning value correction unit does not correct the learning value when a value obtained by integrating the deviations is smaller than a predetermined value. 4. A corrected learning value storage means for storing the learning value corrected by the learning value correction means;
2. The minimum lockup capacity setting means sets the minimum lockup capacity to an average value of a plurality of corrected learning values stored by the corrected learning value storage means. 4. A lockup control device for a torque converter according to any one of items 3 to 3.   The minimum lockup capacity setting means is an average calculated by removing the minimum lockup capacity from a plurality of corrected learning values stored by the corrected learning value storage means excluding a maximum value and a minimum value. The lockup control device for a torque converter according to claim 4, wherein the lockup control device is set to a value.

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