JP2004124969A - Lock-up controller for automatic transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lock-up controller for an automatic transmission capable of quickly converging the coasting lock-up fastening differential pressure to a proper value by learning control, and dispensing with the reattempt of the learning control caused by the misdetermination of a slipping amount. <P>SOLUTION: This lock-up control device comprises a coasting lock-up control means giving initial differential pressure in determining a coasting state from a throttle opening and a car speed, and outputting control differential pressure to achieve predetermined first slipping amount or less; and an initial differential pressure learning means gradually changing initial differential pressure in the releasing direction according to the number of times of coasting lock-up, and learning until the achievement of control differential pressure. Initially, the initial differential pressure learning means applies the initial differential pressure as the maximum initial differential pressure when the slipping amount detected when an initial value of initial differential pressure is determined, is more than a second slipping amount indicating abnormal slipping amount, reduces initial differential pressure by predetermined amount when the detected slipping amount is less than the second slipping amount, and completes learning of initial differential pressure when the control differential pressure is achieved. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lock-up control device for an automatic transmission in which a torque converter is provided with a lock-up clutch and a lock-up clutch is engaged in a predetermined operation range, and more particularly, to a coast during coasting of a vehicle. Related to lockup control.
[0002]
[Prior art]
Regarding coast lockup control, for example, a technique described in Patent Document 1 is known. That is, while the vehicle is in the coasting state (coasting state), the torque converter is connected to the input / output element to prevent a decrease in the engine speed, increase the fuel cut time (fuel injection stop time), and increase fuel efficiency. It is customary to switch from a converter state in which no direct connection is made to a lockup state in which input and output elements are directly connected (coast lockup state).
[0003]
In this case, if the lock-up clutch engagement differential pressure is set to the maximum value in the coast lock-up state, the lock-up clutch engagement differential pressure is reduced from the maximum value when the vehicle is suddenly decelerated from the coasting state. When the up-clutch engagement differential pressure is reduced to release the lock-up, the vehicle tends to be late, and the engine may be stalled. Therefore, in the coast lock-up state, an engine stall is prevented by securing a slip amount when a large torque is input from the wheel side due to rapid deceleration, by setting the fastening differential pressure to a level just before slipping. The last-minute fastening differential pressure is calculated as follows. That is, at the start of coast lock-up, a small engagement differential pressure (hereinafter, referred to as an initial differential pressure) that does not cause a slip is given, and PI control or the like is performed from this initial differential pressure to an engagement differential pressure at which a small slip amount can be obtained. Then, a predetermined offset differential pressure is added to an engagement differential pressure (hereinafter, referred to as a learning differential pressure) at which a small slip amount is obtained. By using this (learning differential pressure + offset differential pressure) as the engagement differential pressure, engine stall is prevented from occurring even in the case of sudden deceleration while improving fuel efficiency.
[0004]
[Patent Document 1]
JP-A-11-182672 (from the lower right corner of page 2 to the upper left corner of page 3)
[0005]
[Problems to be solved by the invention]
However, the above-described related art has the following problems. That is, an initial differential pressure is given, a final fastening differential pressure is calculated from the initial differential pressure, and (learning differential pressure + offset differential pressure) is used as the next initial differential pressure. If the initial differential pressure (hereinafter referred to as the initial value before learning) is large, it takes time to obtain the learning differential pressure, and if a sudden deceleration occurs during this time, the engine may be stalled.
[0006]
Further, in the related art described in Patent Document 1, when a large slip amount is detected, it is determined that an abnormal slip amount has occurred, and the engagement differential pressure of the lock-up clutch is reset to an initial value before learning. I have. Here, the slip amount is calculated from the difference between the engine speed and the turbine speed. In general, the update period of the engine speed is longer than the update period of the turbine speed. In this state, if the wheels are locked due to sudden deceleration, the turbine speed may drop extremely while the engine speed is high due to the delay in the update cycle of the engine speed, and the slip amount becomes extremely large. There is a risk of misjudging that no longer exists. Due to this erroneous determination, the engagement differential pressure of the lock-up clutch is temporarily reset to the maximum value. Therefore, in spite of the fact that the apparent slip amount is increased due to the instantaneous locking of the wheels, the delay in the update cycle of the engine speed, etc., it is erroneously determined that the differential pressure of the lock-up clutch is insufficient, and It is necessary to restart the learning control by resetting the differential pressure to a large value, and there is a problem that it takes time to converge to an appropriate value.
[0007]
The present invention has been made based on the above-described problem, and the coast lock-up engagement differential pressure can be quickly converged to an appropriate value by learning control. Further, learning control is performed again by erroneously determining the slip amount. An object of the present invention is to provide a lockup control device for an automatic transmission that does not need to be redone.
[0008]
[Means for Solving the Problems]
According to the first aspect of the present invention, a torque converter having a lock-up clutch capable of controlling a fastening force, a slip amount detecting means for detecting a slip amount of the lock-up clutch from an engine speed and a turbine speed, and at least a throttle opening When it is determined from the traveling state detecting means for detecting the degree and the vehicle speed, and the detected throttle opening and the vehicle speed that the coast state in which the torque is inputted from the driving wheel side, an initial differential pressure is given, and a preset differential pressure is applied. A coast lock-up control unit that outputs a control differential pressure that is equal to or less than the first slip amount, and gradually changes the initial differential pressure in the release direction according to the number of coast lock-up times until the control differential pressure is reached. An automatic transmission unit lock-up control device, comprising: an initial differential pressure learning means for learning. The upper limit value of the initial differential pressure that does not slip reliably considering the inherent difference in the automatic transmission unit is the maximum initial differential pressure, and the lower limit value of the initial differential pressure that reliably slips considering the inherent difference in the automatic transmission unit is the minimum initial differential pressure. An arbitrary initial differential pressure initial value is provided between the maximum initial differential pressure and the minimum initial differential pressure, and the initial differential pressure learning means sets a slip amount detected when the initial differential pressure initial value is set. When the second slip amount is larger than the second slip amount, the initial differential pressure is set to the maximum initial differential pressure. When the detected slip amount is smaller than the second slip amount, the initial differential pressure is set to the maximum initial differential pressure. When a predetermined amount is reduced and the control differential pressure is reached, learning of the initial differential pressure is completed.
[0009]
According to a second aspect of the present invention, in the automatic transmission lock-up control device according to the first aspect, the coast lock-up control means learns a slip lock-up differential pressure for maintaining the first slip amount. And outputting a value obtained by adding an offset differential pressure that is smaller than the first slip amount to the learned slip lock-up differential pressure as a control differential pressure. And
[0010]
According to a third aspect of the present invention, in the lockup control device for an automatic transmission according to the first or second aspect, a rapid deceleration detecting means for detecting whether the vehicle is in a rapid deceleration state is provided, and the initial differential pressure learning means is provided. Is characterized in that the learning is prohibited when sudden deceleration is detected.
[0011]
According to a fourth aspect of the present invention, in the lock-up control device for an automatic transmission according to any one of the first to third aspects, the initial differential pressure learning means determines that the slip amount detected at the time of the initial differential pressure command is the second slip. The initial differential pressure is set as the maximum initial differential pressure only when a state larger than the amount continues for a predetermined time.
[0012]
Function and Effect of the Invention
In the lock-up control device for an automatic transmission according to the first aspect, since an initial value of the initial differential pressure is provided between the maximum initial differential pressure and the minimum initial differential pressure, learning of the initial differential pressure is completed. This makes it possible to reduce the time until the coasting, and to prevent the engine stall and the lock-up OFF shock due to sudden deceleration during the coast. Further, even if a slip occurs due to an arbitrary initial differential pressure initial value due to a product-specific difference, only the slip amount increases. At the next coast, the maximum initial differential pressure is set, so that the initial differential pressure is set again. Can be performed.
[0013]
In the lock-up control device for an automatic transmission according to claim 2, the slip lock-up differential pressure for maintaining the first slip amount is determined by the slip lock-up differential pressure learning unit included in the coast lock-up control means. Learned. By outputting the value obtained by adding the learned differential value of the slip lock-up differential pressure to the offset differential pressure as the control differential pressure, it is possible to control the lock-up clutch with a differential pressure as short as possible without slipping during coasting, thereby improving fuel efficiency. In addition, engine stall and lock-up OFF shock due to sudden deceleration during coasting can be prevented.
[0014]
In the automatic transmission lock-up control device according to the third aspect, learning of the initial differential pressure is prohibited when sudden deceleration is detected. That is, although the apparent slip amount is increased due to instantaneous locking of the wheels due to rapid deceleration or a delay in the update cycle of the engine speed, etc., it is erroneously determined that the engagement differential pressure of the lock-up clutch is insufficient, and the engagement is determined. It is possible to prevent the differential pressure from being reset to a large value, and prevent the problem that it takes time to converge to an appropriate value by performing the learning control again.
[0015]
In the automatic transmission lock-up control device according to the fourth aspect, the initial differential pressure is reduced only when the state in which the slip amount detected at the time of the initial differential pressure command is larger than the second slip amount continues for a predetermined time. The maximum initial differential pressure. Therefore, if the rapid deceleration state is detected during the continuation of the predetermined time, the learning control is prohibited at this stage, so that the maximum initial differential pressure is not set and erroneous learning can be reliably prevented.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
(Embodiment 1)
FIG. 1 is a diagram illustrating a control system of an automatic transmission including a belt-type continuously variable transmission 3 (hereinafter, referred to as CVT) according to the first embodiment.
[0017]
1 is a torque converter, 2 is a lock-up clutch, 3 is a CVT, 4 is a primary speed sensor, 5 is a secondary speed sensor, 6 is a hydraulic control valve unit, 8 is an oil pump driven by an engine, and 9 is CVT control. The unit 10 is a throttle opening sensor, and 11 is an engine speed sensor.
[0018]
A torque converter 1 is connected to the engine output shaft as a rotation transmission mechanism, and a lock-up clutch 2 that directly connects the engine and the CVT 3 is provided. The output side of the torque converter 1 is connected to the ring gear 21 of the forward / reverse switching mechanism 20. The forward / reverse switching mechanism 20 includes a planetary gear mechanism including a ring gear 21 connected to the engine output shaft 12, a pinion carrier 22, and a sun gear 23 connected to the transmission input shaft 13. The pinion carrier 22 is provided with a reverse brake 24 for fixing the pinion carrier 22 to the transmission case, and a forward clutch 25 for integrally connecting the transmission input shaft 13 and the pinion carrier 22.
[0019]
A primary pulley 30 a of the CVT 3 is provided at an end of the transmission input shaft 13. The CVT 3 includes the primary pulley 30a, the secondary pulley 30b, a belt 34 that transmits the rotational force of the primary pulley 30a to the secondary pulley 30b, and the like. The primary pulley 30a is provided with a fixed conical plate 31 that rotates integrally with the transmission input shaft 13, and is opposed to the fixed conical plate 31 to form a V-shaped pulley groove. The movable conical plate 32 is movable in the axial direction of the machine input shaft 13.
[0020]
The secondary pulley 30b is provided on the driven shaft 38. The secondary pulley 30 b has a fixed conical plate 35 that rotates integrally with the driven shaft 38, a V-shaped pulley groove that is disposed opposite to the fixed conical plate 35, and that is driven by hydraulic pressure acting on the secondary pulley cylinder chamber 37. And a movable conical plate 36 that can move in the axial direction.
[0021]
The torque input from the engine output shaft 12 to the CVT 3 as described above is transmitted to the CVT 13 via the torque converter 1 and the forward / reverse switching mechanism 20. The rotational force of the transmission input shaft 13 is transmitted to the differential via a primary pulley 30a, a belt 34, a secondary pulley 30b, a driven shaft 38, a driving gear, an idler gear, an idler shaft, a pinion, and a final gear.
[0022]
At the time of power transmission as described above, the movable conical plate 32 of the primary pulley 30a and the movable conical plate 36 of the secondary pulley 30b are moved in the axial direction to change the contact position radius with the belt 34, so that the primary pulley 30a The rotation ratio between the secondary pulley 30b, that is, the gear ratio is changed. Such control of changing the width of the V-shaped pulley groove is performed by hydraulic control of the primary pulley cylinder chamber 33 or the secondary pulley cylinder chamber 37 via the CVT control unit 9.
[0023]
The CVT control unit 9 has a throttle opening from the throttle opening sensor 10, a primary rotation speed (corresponding to a turbine rotation speed described in claims) from the primary rotation speed sensor 4, and an engine rotation speed from the engine rotation speed sensor 11. Is input. The control signal is calculated based on the input signal, and the control signal is output to the hydraulic control valve unit 6.
[0024]
The hydraulic control valve unit 6 controls the shift by supplying a control pressure to the primary pulley cylinder chamber 33 and the secondary pulley cylinder chamber 37 based on a control signal from the CVT control unit 9, and applies the control signal to the lock-up clutch 2. The engagement force of the lock-up clutch 2 is controlled by the pressure difference between the pressure and the release pressure.
[0025]
FIG. 2 is a hydraulic circuit diagram of the belt-type continuously variable transmission according to the first embodiment.
Reference numeral 40 denotes a pressure regulator valve that regulates the discharge pressure of the oil pump 8 supplied from the oil passage 41 as a line pressure. An oil passage 42 communicates with the oil passage 41. The oil passage 42 is a pulley clamp pressure supply oil passage that supplies a pulley clamp pressure for clamping the belt 34 to the primary pulley cylinder chamber 33 and the secondary pulley cylinder chamber 37 of the CVT 3. The oil passage 43 connected to the oil passage 42 supplies the original pressure of the pilot valve 50.
[0026]
The hydraulic pressure drained from the pressure regulator valve 40 is supplied to the clutch regulator valve 60 via the oil passage 46. As described above, by adjusting the oil pressure lower than the oil pressure generated by the pressure regulator valve 40 by the clutch regulator valve 60, the oil pressure supplied as the engagement pressure of the forward clutch does not become higher than the pulley clamp pressure.
[0027]
The oil passage 46 communicates with the oil passage 42 and an oil passage 44 having an orifice 45. Clutch regulator valve 60 regulates the oil pressure in oil passage 46 and oil passage 61. The oil pressure in the oil passage 61 is supplied to the select switching valve 80 and the select control valve 90.
[0028]
Reference numeral 50 denotes a pilot valve for setting a constant supply pressure to the lock-up solenoid 71 and the select switching solenoid 70 via the oil passage 51. The output pressure of the select switching solenoid 70 is supplied to the select switching valve 80, and controls the operation of the select switching valve 80. The output pressure of the lock-up solenoid 71 is supplied to the select switching valve 80.
[0029]
The select switching valve 80 is operated by a select switching solenoid 70. The select switching valve 80 is connected as an input port to an oil passage 72 for supplying a signal pressure from a lock-up solenoid 71, an oil passage 61 regulated by a clutch regulator valve 60 is connected, and a select control valve 90 The regulated oil passage 93 is connected. Further, as an output port, an oil passage 81 for supplying forward clutch pressure to a manual valve (not shown) is connected, an oil passage 82 for supplying oil pressure to the lock-up control valve 100 is connected, and a spool 92 of the select control valve 90 is connected. An oil passage 83 for supplying an operating oil pressure is connected, and a drain oil passage 84 for draining the oil pressure is connected.
[0030]
The select control valve 90 is connected, as an input port, to an oil passage 62 regulated by the clutch regulator valve 60 and an oil passage 83 for supplying a signal pressure of the lock-up solenoid 71. Then, the hydraulic pressure is adjusted by controlling the communication state between the oil passage 62 and the oil passage 93.
[0031]
When the signal of the select switching solenoid 70 is ON, the signal pressure of the lock-up solenoid 71 acts as the signal pressure of the select control valve 90 via the select switching valve 80. Then, the hydraulic pressure adjusted by the select control valve 90 is supplied to a manual valve (not shown).
[0032]
On the other hand, when the signal of the select switching solenoid 70 is OFF, the signal pressure of the lock-up solenoid 71 is supplied to the lock-up control valve 100 via the select switching valve 80 to control the release pressure and the apply pressure of the lock-up clutch. I do.
[0033]
The lock-up control valve 100 is connected as an input port to an oil passage 64 that is hydraulic pressure drained from the clutch regulator valve 60 and is regulated by the torque converter regulator valve 110, and is connected to the oil drained from the torque converter regulator valve 110. Road 105 is connected.
[0034]
On the other hand, as output ports, an oil passage 102 and an oil passage 103 communicating with an oil passage 101 that supplies a release pressure to the torque converter 1 are connected, and oil passages 106 and 108 that supply an apply pressure to the torque converter 1 are connected. An oil passage 107 for draining oil pressure is connected to an oil cooler (not shown).
[0035]
The torque converter regulator valve 110 regulates the oil pressure drained from the clutch regulator valve 60 and supplies the oil pressure to the lock-up control valve 100 via the oil passage 64.
[0036]
FIG. 3 is a lockup control map according to the first embodiment. This map uses the vehicle speed on the horizontal axis and the throttle opening on the vertical axis to determine the region where the operating point determined from the vehicle speed and the throttle opening indicating the running state of the vehicle is located. Perform up control.
[0037]
A lock-up OFF line and a lock-up ON line are set in this lock-up control map. The lock-up ON line and the lock-up OFF line have hysteresis (region B), and when the operating point passes through the lock-up ON line to the high vehicle speed side (or the low throttle opening side) (region C), the lock-up clutch 2 A complete fastening state is achieved by a fastening force corresponding to the input torque to the torque converter 1. When the lock-up clutch 2 passes through the lock-up OFF line to the low vehicle speed side (or the high throttle opening degree side) in the fully engaged state or is in the region A, the lock-up clutch 2 is completely released.
Further, a coast lockup region (D region) is set in a region smaller than a predetermined throttle opening (for example, a 3/32 opening) and the vehicle speed is equal to or higher than the predetermined vehicle speed. This coast lockup area is used to prevent the engine speed from decreasing while the vehicle is coasting, to increase the fuel cut time (fuel injection stop time), and to increase the fuel efficiency. I do. If the lock-up clutch engagement differential pressure is increased in the coast lock-up state, the lock-up clutch engagement differential pressure will decrease from the maximum value when the vehicle is suddenly decelerated from the coasting state. When the pressure is reduced and the lock-up is released, it tends to be late, and the engine may be stalled. Therefore, in the coast lock-up state, an engine stall is prevented by securing a slip amount when a large torque is input from the wheel side due to rapid deceleration, by setting the fastening differential pressure to a level just before slipping. When sudden deceleration occurs, the lock-up clutch 2 is released to prevent engine stall.
The last-minute fastening differential pressure is calculated as follows. That is, at the start of coast lock-up, a small engagement differential pressure (hereinafter, referred to as an initial differential pressure) that does not cause a slip is given, and PI control or the like is performed from this initial differential pressure to an engagement differential pressure at which a small slip amount can be obtained. Then, a predetermined offset differential pressure is added to an engagement differential pressure (hereinafter, referred to as a learning differential pressure) at which a small slip amount is obtained. By using this (learning differential pressure + offset differential pressure) as the engagement differential pressure, engine stall is prevented from occurring even in the case of sudden deceleration while improving fuel efficiency.
[0038]
FIG. 3 is a flowchart showing the control contents of the lock-up control in the first embodiment.
[0039]
In step 101, it is determined whether or not the lock-up engagement flag F = 1. If F = 1, it is determined that the lock-up clutch is engaged, and the routine proceeds to step 106, otherwise proceeds to step 102.
[0040]
In step 102, it is determined whether or not the area is the C area. If the area is the C area, the process proceeds to step 107; otherwise, the process proceeds to step 103.
[0041]
In step 103, it is determined whether or not the area is the D area. If the area is the D area, the process proceeds to step 109; otherwise, the process proceeds to step 104.
[0042]
In step 104, lock-up OFF control is performed.
[0043]
In step 105, the lock-up engagement flag F is set to 0.
[0044]
In step 106, it is determined whether or not the area is in the area B or area C. If the area is in the area BorC, the process proceeds to step 107. Otherwise, the process proceeds to step 104 to perform lock-up OFF control.
[0045]
In step 107, the lock-up engagement flag F is set to 1.
[0046]
In step 108, a complete engagement control for completely engaging the lock-up clutch is executed.
[0047]
In step 109, coast lockup learning control is executed.
[0048]
The above-described coast lockup learning control will be described with reference to the flowchart of FIG.
[0049]
In step 201, it is determined whether or not the first coast lockup control is performed. If the first coast lockup control is performed, the process proceeds to step 202; otherwise, the process proceeds to step 209.
[0050]
In step 202, the slippage is reliably performed in consideration of the inherent difference in the automatic transmission unit, the maximum initial differential pressure Max, which is the upper limit of the initial differential pressure that does not reliably slip, taking into account the inherent difference in the automatic transmission unit, and the inherent difference in the automatic transmission unit. An arbitrary initial value Po of the initial differential pressure between the minimum initial differential pressure Min and the lower limit value of the initial differential pressure is set.
[0051]
In step 203, it is determined whether or not the slip amount Slip is larger than the first slip amount Slip1, and if it is larger, the process proceeds to step 210, and if smaller, the process proceeds to step 204.
[0052]
In step 204, the lock-up differential pressure is controlled by PI control so as to reach the target slip amount Slip2 which is a minute slip amount set in advance.
[0053]
In step 205, it is determined whether or not the target slip amount Slip2 has been reached, and if so, the process proceeds to step 206, and otherwise the step 204 is repeated.
[0054]
In step 206, it is determined whether a predetermined time has elapsed. If the predetermined time has elapsed, the process proceeds to step 207. Otherwise, steps 204 and 205 are repeated.
[0055]
In step 207, the learning value is updated to the differential pressure obtained in step 204.
[0056]
In step 208, a value obtained by adding an offset differential pressure that will be the minimum differential pressure that does not cause slippage to the updated learning value is output as the differential engagement pressure.
[0057]
In step 209, the learning value + offset differential pressure calculated in step 208 is used as the initial differential pressure.
[0058]
In step 210, it is determined whether or not the vehicle is in a rapid deceleration state. The determination of rapid deceleration may be made based on, for example, whether the amount of change (deceleration) of the primary pulley rotation speed per unit time is equal to or greater than a predetermined value.
[0059]
In step 211, it is determined whether or not a predetermined time has elapsed. If the predetermined time has elapsed, the process proceeds to step 212, and otherwise, steps 203 → 210 are repeated.
[0060]
In step 212, the maximum initial differential pressure Max is set as the initial differential pressure.
[0061]
In step 213, lock-up OFF control is executed.
[0062]
The above-described coast lockup learning control will be described with reference to the time chart of FIG. It should be noted that this is a time chart when the initial coast lock-up control is determined in step 201 and no abnormal slip occurs.
In steps 201 and 202, as shown in FIG. 6, the lock-up control device according to the first embodiment uses the maximum initial differential pressure Max and the minimum initial differential pressure Min as the initial differential pressures set at the first coast lock-up control. Is started from an arbitrary initial differential pressure Po between. Thus, for example, learning can be completed earlier than when the control is started from the maximum initial differential pressure Max as in the related art (corresponding to the first aspect of the invention).
[0063]
Next, it is determined whether or not the slip amount Slip is greater than a slip amount Slip1 (corresponding to a second slip amount described in claims) indicating an abnormal slip amount. It is determined that even if there is an inherent difference of the automatic transmission unit, an engagement differential pressure that does not cause any problem in the learning control can be obtained. Then, using this initial differential pressure as a starting differential pressure, the lockup clutch 2 locks up by PI control so as to obtain a preset target slip amount Slip2 (corresponding to the first slip amount described in the claims). Control the differential pressure. When the state in which the target slip amount Slip2 is obtained by this control continues for a predetermined time, it is determined that the target slip amount Slip2 has been stably obtained, and the lockup differential pressure at this time is set as a learning value. To this learning value, a preset offset differential pressure that can obtain a fastening force just before the lock-up clutch 2 slips is added, and this (learning value + offset differential pressure) is added to the initial value in the next coast lock-up control. Set as differential pressure. As a result, the lock-up clutch engagement force can be set to a marginal value, and the lock-up clutch slips even if a large torque is input from the drive wheels due to sudden deceleration while improving fuel efficiency. Engine stall can be prevented (corresponding to claims 1 and 2).
[0064]
FIG. 7 is a time chart when the initial coast lock-up control is determined in step 201 and an abnormal slip occurs. When the initial differential pressure Po is set in steps 201 and 202 and it is determined that an abnormal slip has occurred, it is determined in step 210 whether the vehicle is in a rapid deceleration state. At this stage, if the rapid deceleration state has not been detected yet, it is determined whether a predetermined time has elapsed.
If the abnormal slip amount is detected even during the lapse of the predetermined time, and abnormal slip is determined for some reason other than sudden deceleration, the maximum initial differential pressure Max is set as the reset initial differential pressure as the initial differential pressure, and the maximum initial differential pressure is set. Learning control is started from the differential pressure Max.
[0065]
FIG. 8 is a time chart when a plurality of coast lock-up controls are performed and an abnormal slip occurs. When it is determined that the vehicle is in the coast state with the accelerator released, coast lockup control is executed. At this time, when the brake is depressed, the vehicle starts to decelerate, a large torque is input from the drive wheel side, and the primary rotational speed starts to decrease.
At time t2, the timer counts when the value exceeds the slip value Slip1, which is the determination value of the abnormal slip amount. Here, the slip amount is calculated from the difference between the engine speed and the turbine speed (primary speed). In general, the update period of the engine speed is longer than the update period of the turbine speed. In this state, if the wheels are locked due to sudden deceleration, the turbine speed may drop extremely while the engine speed is high due to the delay in the update cycle of the engine speed, and the slip amount becomes extremely large. There is a risk of misjudging that no longer exists. Therefore, erroneous determination can be prevented by determining an abnormal slip only when the abnormal slip has continued for a predetermined time (corresponding to the invention described in claim 4).
[0066]
If a sudden deceleration determination is made at time t3 during the counting of the timer, the process proceeds to lockup OFF control. That is, if the vehicle is in a rapid deceleration state, the rapid deceleration state is detected within a predetermined time counted by the timer, and the process proceeds to step 213 to execute lockup OFF control. Therefore, the process does not proceed to Steps 205 to 208 and erroneous learning is not performed (corresponding to the inventions of claims 3 and 4). Further, even if the predetermined time has elapsed at time t4 and the abnormal slip determination is made, the learning value is not reset, so that the high engagement differential pressure reset at the next coast lock-up control is set. Therefore, problems such as occurrence of lock-up OFF shock and engine stall can be avoided.
[0067]
(Other embodiments)
The embodiment based on the embodiment has been described above, but the specific configuration is not limited to this embodiment and does not depart from the gist of the invention according to each claim in the claims. As long as the design is changed or added, it is acceptable.
[Brief description of the drawings]
FIG. 1 is an overall system diagram of a lockup control device for an automatic transmission according to a first embodiment.
FIG. 2 is a circuit diagram illustrating a hydraulic circuit of the automatic transmission according to the first embodiment.
FIG. 3 is a lockup control map according to the first embodiment.
FIG. 4 is a flowchart illustrating lock-up control according to the first embodiment.
FIG. 5 is a flowchart illustrating coast lockup control according to the first embodiment.
FIG. 6 is a diagram illustrating a relationship between the number of coast lockups and an initial differential pressure when no abnormal slip occurs according to the first embodiment.
FIG. 7 is a diagram illustrating a relationship between the number of coast lockups and an initial differential pressure when an abnormal slip occurs in the first embodiment.
FIG. 8 is a time chart showing switching from coast lock-up control to lock-up control during rapid deceleration in the first embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Torque converter 2 Lock-up clutch 3 Belt-type continuously variable transmission 4 Primary speed sensor 6 Hydraulic control valve unit 8 Oil pump 9 Control unit 10 Throttle opening sensor 11 Engine speed sensor 12 Engine output shaft 13 Transmission input shaft 20 Forward / reverse switching mechanism 21 Ring gear 22 Pinion carrier 23 Sun gear 24 Reverse brake 25 Forward clutch 30a Primary pulley 30b Secondary pulley 31 Fixed conical plate 32 Movable conical plate 33 Primary pulley cylinder chamber 34 Belt 35 Fixed conical plate 36 Movable conical plate 37 Secondary pulley Cylinder chamber 38 Followed shaft 40 Pressure regulator valve 45 Orifice 50 Pilot valve 60 Clutch regulator valve 70 Select switch Ching solenoid 71 Lock-up solenoid 80 Select switching valve 90 Select control valve 92 Spool 100 Lock-up control valve 101 Oil passage 110 Torque converter regulator valve

Claims (4)

A torque converter having a lock-up clutch capable of controlling the engagement force,
Slip amount detecting means for detecting a slip amount of the lock-up clutch from an engine speed and a turbine speed,
Traveling state detecting means for detecting at least the throttle opening and the vehicle speed;
When it is determined from the detected throttle opening and the vehicle speed that a coast state in which torque is being input from the driving wheel side, an initial differential pressure is given, and a control differential pressure that is equal to or less than a first slip amount set in advance. Coast lockup control means for outputting;
Initial differential pressure learning means for gradually changing the initial differential pressure in the release direction in accordance with the number of coast lockups and learning until the control differential pressure is reached,
In the automatic transmission unit lock-up control device having
The upper limit of the initial differential pressure that does not slip reliably considering the inherent difference in the automatic transmission unit is the maximum initial differential pressure,
The lower limit of the initial differential pressure that reliably slides in consideration of the inherent difference in the automatic transmission unit is the minimum initial differential pressure,
Providing an arbitrary initial differential pressure initial value between the maximum initial differential pressure and the minimum initial differential pressure,
The initial differential pressure learning means sets the initial differential pressure to the maximum when the slip amount detected when the initial differential pressure is set to the initial value is larger than a second slip amount larger than the first slip amount. When the detected slip amount is smaller than the second slip amount, the initial differential pressure is reduced by a predetermined amount, and when the control differential pressure is reached, learning of the initial differential pressure is completed. A lock-up control device for an automatic transmission. The lockup control device for an automatic transmission according to claim 1,
The coast lock-up control means includes a slip lock-up differential pressure learning unit that learns a slip lock-up differential pressure for maintaining the first slip amount. A lock-up control device for an automatic transmission, which outputs a value obtained by adding an offset differential pressure so as to be less than one slip amount as a control differential pressure. The lockup control device for an automatic transmission according to claim 1 or 2,
Providing rapid deceleration detection means for detecting whether the vehicle is in a rapid deceleration state,
The lock-up control device for an automatic transmission, wherein the initial pressure difference learning means prohibits the learning when a sudden deceleration is detected. The lockup control device for an automatic transmission according to any one of claims 1 to 3,
The initial differential pressure learning means sets the initial differential pressure as the maximum initial differential pressure only when a state in which the slip amount detected at the time of the initial differential pressure command is larger than the second slip amount continues for a predetermined time. A lock-up control device for an automatic transmission.

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