JP4129161B2 - Automatic transmission lockup control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a lockup control device for an automatic transmission that includes a lockup clutch in a torque converter section and that engages a lockup clutch in a predetermined operating region, and more particularly, during coasting of a vehicle (coast running). It relates to lockup control.
[0002]
[Prior art]
Regarding the coast lock-up control, for example, a technique described in Patent Document 1 is known. In other words, while the vehicle is coasting (coasting), the torque converter is connected to the input / output elements to prevent the engine speed from decreasing and increase the fuel cut time (fuel injection stop time) to increase fuel consumption. It is a common practice to change from a converter state in which there is no direct connection to a lockup state (coast lockup state) in which input / output elements are directly connected.
[0003]
In this case, if the lockup clutch engagement differential pressure is set to the maximum value in the coast lockup state, the lockup 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, there is a possibility that the engine will stall. Therefore, the engine differential is prevented by preventing the engine from stalling by ensuring the slip amount when a large torque is input from the wheel side due to sudden deceleration, with the tightening differential pressure being the minimum that does not slip in the coast lock-up state. This marginal fastening differential pressure is calculated as follows. That is, a small engagement differential pressure (hereinafter referred to as an initial differential pressure) that does not slip once is given at the start of coast lockup, and PI control or the like is used from this initial differential pressure to an engagement differential pressure at which a minute slip amount can be obtained. Then, a predetermined offset differential pressure is added to the 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 even when the vehicle is suddenly decelerated while improving fuel efficiency.
[0004]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 11-182672 (lower right of page 2 to upper left of page 3)
[0005]
[Problems to be solved by the invention]
However, the above-described prior art has the following problems. That is, the initial differential pressure is given, the 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, but at the start of learning given at the time of product shipment If the initial differential pressure (hereinafter referred to as the pre-learning initial value) is large, it takes time to obtain the learned differential pressure. If sudden deceleration occurs during this time, engine stall may occur.
[0006]
Further, the prior art described in Patent Document 1 is configured to determine that an abnormal slip amount has occurred when a large slip amount is detected, and to reset the engagement differential pressure of the lockup clutch to the initial value before learning. Yes. Here, the slip amount is calculated from the difference between the engine speed and the turbine speed, but generally the update period of the engine speed is longer than the update period of the turbine speed. In this state, if the wheel is locked due to sudden deceleration, the turbine speed may be extremely reduced with the engine speed being high due to the delay in the update period of the engine speed, and the slip amount is extremely large. There is a risk of misjudging it. Due to this erroneous determination, the engagement differential pressure of the lockup clutch is once reset to the maximum value. Therefore, in spite of the fact that the apparent slip amount increased due to momentary locking of the wheels or delay in the engine speed update cycle, etc. There is a problem that it is necessary to perform learning control again by resetting the differential pressure to a large value, and it takes time to converge to an appropriate value.
[0007]
The present invention has been made on the basis of the above-described problems. The coast lock-up engagement differential pressure can be quickly converged to an appropriate value by learning control, and further learning control can be performed again by erroneous determination of 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 lockup clutch capable of controlling the fastening force, slip amount detecting means for detecting the slip amount of the lockup clutch from the engine speed and the turbine speed, and at least the throttle opening. When it is determined that the coasting state in which torque is input from the drive wheel side from the detected throttle opening degree and vehicle speed, the initial differential pressure is given and set in advance. Coast lockup control means for outputting a control differential pressure that is equal to or less than the first slip amount, and gradually changing the initial differential pressure in the releasing direction according to the number of coast lockups until the control differential pressure is reached. An automatic transmission unit lockup control device comprising an initial differential pressure learning means for learning, wherein the automatic transmission unit Of the initial differential pressure non-slip to ensure that takes into account the inherent differences in the door lower limit The value of the initial differential pressure is the maximum initial differential pressure, and the initial differential pressure that slides reliably considering the inherent difference in the automatic transmission unit. upper limit When the value 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 is set to the initial differential pressure initial value When the detected slip amount is larger than the second slip amount larger than the first slip amount, the initial differential pressure is set as the maximum initial differential pressure, and 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.
[0009]
According to a second aspect of the present invention, in the lockup control device for an automatic transmission according to the first aspect, the coast lockup control means learns a slip lockup differential pressure for maintaining the first slip amount. A slip lockup differential pressure learning unit that outputs a value obtained by adding an offset differential pressure that is less than the first slip amount to the learned slip lockup 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 sudden deceleration detecting means for detecting whether or not the vehicle is in a sudden 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 lockup control device for an automatic transmission according to the first to third aspects, the initial differential pressure learning means is configured such 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]
Operation and effect of the invention
In the lockup control device for an automatic transmission according to claim 1, learning of the initial differential pressure is completed by providing an arbitrary initial differential pressure initial value between the maximum initial differential pressure and the minimum initial differential pressure. It is possible to shorten the time until the engine is stopped, and it is possible to prevent engine stall and lock-up OFF shock due to sudden deceleration during coasting. In addition, even if slip occurs due to any initial differential pressure initial value due to the inherent difference of the product, the slip amount only increases, and the initial differential pressure is again set by setting the maximum initial differential pressure at the next coast. Learning control can be executed.
[0013]
In the lockup control device for an automatic transmission according to claim 2, in the slip lockup differential pressure learning unit included in the coast lockup control means, the slip lockup differential pressure for maintaining the first slip amount is To be learned. By outputting the value obtained by adding the offset differential pressure to the learned slip lock-up differential pressure as the control differential pressure, it becomes possible to control with the differential pressure that the lock-up clutch does not slip when coasting, improving fuel efficiency The engine stall and the lock-up OFF shock due to sudden deceleration during coasting can be prevented.
[0014]
In the automatic transmission lockup control device according to the third aspect, the learning of the initial differential pressure is prohibited when the rapid deceleration is detected. In other words, despite the fact that the apparent slip amount increased due to momentary locking of the wheels due to sudden deceleration or delay in the engine speed update cycle, it was mistakenly determined that the engagement differential pressure of the lockup clutch was insufficient, and the engagement was It is possible to prevent the differential pressure from being reset to a large value, and it is possible to prevent the problem that it takes time to converge to an appropriate value by performing learning control again.
[0015]
In the lockup control device for an automatic transmission according to claim 4, the initial differential pressure is applied only when the slip amount detected at the time of the initial differential pressure command is larger than the second slip amount for a predetermined time. Maximum initial differential pressure. Therefore, if a sudden deceleration state is detected during a predetermined time, 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]
DETAILED DESCRIPTION OF THE INVENTION
(Embodiment 1)
FIG. 1 is a diagram showing a control system of an automatic transmission provided with a belt-type continuously variable transmission 3 (hereinafter referred to as CVT) in 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 the engine, and 9 is CVT control A 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 lockup 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 that fixes the pinion carrier 22 to the transmission case, and a forward clutch 25 that integrally connects the transmission input shaft 13 and the pinion carrier 22.
[0019]
A primary pulley 30a of the CVT 3 is provided at the 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 30 a has a fixed conical plate 31 that rotates integrally with the transmission input shaft 13, a V-shaped pulley groove that is disposed opposite to the fixed conical plate 31, and is shifted by hydraulic pressure that acts on the primary pulley cylinder chamber 33. The movable conical plate 32 is movable in the axial direction of the machine input shaft 13.
[0020]
The secondary pulley 30 b 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 a hydraulic pressure that acts on the secondary pulley cylinder chamber 37. The movable conical plate 36 is movable in the axial direction.
[0021]
The rotational force 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 device through the primary pulley 30a, belt 34, secondary pulley 30b, driven shaft 38, drive gear, idler gear, idler shaft, pinion, and final gear.
[0022]
During the 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, whereby the primary pulley 30a The rotation ratio between the secondary pulley 30b, that is, the gear ratio is changed. Control for changing the width of the V-shaped pulley groove is performed by hydraulic control to 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 includes a throttle opening sensor 10 to a throttle opening, a primary rotation speed sensor 4 to a primary rotation speed (corresponding to the turbine rotation speed described in the claims), and an engine rotation speed sensor 11 to an engine rotation speed. Etc. are input. A control signal is calculated based on this input signal, and the control signal is output to the hydraulic control valve unit 6.
[0024]
The hydraulic control valve unit 6 performs shift control by supplying 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 to the lockup clutch 2. The fastening force of the lockup clutch 2 is controlled by the differential pressure 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.
A pressure regulator valve 40 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. Further, the oil passage 43 communicated with 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. In this way, by adjusting the hydraulic pressure lower than the hydraulic pressure generated by the pressure regulator valve 40 by the clutch regulator valve 60, the hydraulic pressure supplied as the fastening 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 communicates with an oil passage 44 having an orifice 45. The clutch regulator valve 60 regulates the oil pressure in the oil passage 46 and the 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]
A pilot valve 50 sets a constant supply pressure to the lockup 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 lockup solenoid 71 is supplied to the select switching valve 80.
[0029]
The select switching valve 80 is operated by a select switching solenoid 70. An oil passage 72 that supplies a signal pressure from the lockup solenoid 71 is connected to the select switching valve 80 as an input port. An oil passage 61 that is regulated by the clutch regulator valve 60 is connected to the select switching valve 80. A regulated oil passage 93 is connected. Further, as an output port, an oil passage 81 for supplying forward clutch pressure is connected to a manual valve (not shown), an oil passage 82 for supplying hydraulic pressure to the lockup control valve 100 is connected, and the spool 92 of the select control valve 90 is connected. An oil passage 83 for supplying hydraulic pressure to be operated is connected, and a drain oil passage 84 for draining hydraulic pressure is connected.
[0030]
Connected to the select control valve 90 is an oil passage 62 that is regulated by the clutch regulator valve 60 and an oil passage 83 that supplies the signal pressure of the lockup solenoid 71 as an input port. Then, the hydraulic pressure is regulated 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 lockup 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 lockup solenoid 71 is supplied to the lockup control valve 100 via the select switching valve 80 to control the release pressure and the apply pressure of the lockup clutch. To do.
[0033]
The lockup control valve 100 is connected to an oil passage 64 that is oil pressure drained from the clutch regulator valve 60 and regulated by the torque converter regulator valve 110 as an input port, and oil drained from the torque converter regulator valve 110. A path 105 is connected.
[0034]
On the other hand, as an output port, an oil passage 102 and an oil passage 103 communicating with an oil passage 101 for supplying release pressure to the torque converter 1 are connected, and oil passages 106 and 108 for supplying an apply pressure to the torque converter 1 are connected. An oil passage 107 for draining hydraulic pressure is connected to an oil cooler (not shown).
[0035]
The torque converter regulator valve 110 regulates the hydraulic pressure drained from the clutch regulator valve 60 and supplies the hydraulic pressure to the lockup control valve 100 via the oil passage 64.
[0036]
FIG. 3 is a lockup control map according to the first embodiment. This map takes the vehicle speed on the horizontal axis and the throttle opening on the vertical axis, determines which region the driving point is determined from the vehicle speed and throttle opening indicating the vehicle running state, and locks corresponding to that region. Perform up-control.
[0037]
In this lockup control map, a lockup OFF line and a lockup ON line are set. The lock-up ON line and the lock-up OFF line have hysteresis (B range). When the operating point passes the lock-up ON line to the high vehicle speed side (or low throttle opening side) (C range), the lock-up clutch 2 is A complete fastening state is achieved by a fastening force corresponding to the input torque to the torque converter 1. When the lockup clutch 2 is fully engaged and the lockup OFF line is passed to the low vehicle speed side (or the high throttle opening side) or is in the A region, the lockup clutch 2 is completely released.
A coast lockup region (D region) is set in a region smaller than a predetermined throttle opening (for example, 3/32 opening) and the vehicle speed is equal to or higher than the predetermined vehicle speed. This coast lock-up area is used to prevent the engine speed from decreasing while the vehicle is in a coasting state, lengthen the fuel cut time (fuel injection stop time), and increase the fuel consumption. To do. If the lockup clutch engagement differential pressure is increased in the coast lockup state, the lockup clutch engagement differential pressure will be reduced from the maximum value when the vehicle is suddenly decelerated from the coasting state. When the pressure is lowered and the lockup is released, there is a possibility that the engine will stall, causing the engine to stall. Therefore, the engine differential is prevented by preventing the engine from stalling by ensuring the slip amount when a large torque is input from the wheel side due to sudden deceleration, with the tightening differential pressure being the minimum that does not slip in the coast lock-up state. When sudden deceleration occurs, the lockup clutch 2 is released to prevent engine stall.
This marginal fastening differential pressure is calculated as follows. That is, a small engagement differential pressure (hereinafter referred to as an initial differential pressure) that does not slip once is given at the start of coast lockup, and PI control or the like is used from this initial differential pressure to an engagement differential pressure at which a minute slip amount can be obtained. Then, a predetermined offset differential pressure is added to the 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 even when the vehicle is suddenly decelerated while improving fuel efficiency.
[0038]
Figure 4 FIG. 3 is a flowchart showing the control content of lockup 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 process proceeds to step 106. Otherwise, the process 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;
[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.
[0042]
In step 104, lock-up OFF control is performed.
[0043]
In step 105, the lockup engagement flag F is set to zero.
[0044]
In step 106, it is determined whether the area is in the B area or the C area. If the area is in the BorC area, the process proceeds to step 107. Otherwise, the process proceeds to step 104 and lockup OFF control is performed.
[0045]
In step 107, the lockup engagement flag F = 1 is set.
[0046]
In step 108, complete engagement control for completely engaging the lockup clutch is executed.
[0047]
In step 109, coast lockup learning control is executed.
[0048]
The above-described coast lock-up learning control will be described based on 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, an initial differential pressure that does not slip reliably, taking into account the inherent difference in the automatic transmission unit. lower limit The maximum initial differential pressure Max, which is the value, and the initial differential pressure that is surely slipped taking into account the inherent difference in the automatic transmission unit upper limit An arbitrary initial differential pressure initial value Po between the minimum initial differential pressure Min that is a value is set.
[0051]
In step 203, it is determined whether or not the slip amount Slip is larger than the first slip amount Slip1. If it is larger, the process proceeds to step 210. If it is smaller, the process proceeds to step 204.
[0052]
In step 204, the lockup differential pressure is controlled by PI control so that the target slip amount Slip2 which is a preset minute slip amount is obtained.
[0053]
In step 205, it is determined whether or not the target slip amount Slip2 has been reached. If it has reached, the process proceeds to step 206, and step 204 is repeated otherwise.
[0054]
In step 206, it is determined whether or not 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 is a marginal engagement differential pressure that does not slip to the updated learning value is output as the engagement differential pressure.
[0057]
In step 209, the learned 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 sudden deceleration state. The determination of sudden deceleration may be made, for example, based on whether or not the amount of change (deceleration) per unit time of the primary pulley rotational speed 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. Otherwise, step 203 to step 210 are repeated.
[0060]
In step 212, the maximum initial differential pressure Max is set as the initial differential pressure.
[0061]
In step 213, lockup OFF control is executed.
[0062]
The above coast lockup learning control will be described with reference to the time chart of FIG. Here, it is a time chart when the first coast lock-up control is determined in step 201 and no abnormal slip occurs.
In step 201 and step 202, as shown in FIG. 6, in the lockup control device of the first embodiment, the maximum initial differential pressure Max and the minimum initial differential pressure Min are set as initial differential pressures set during the first coast lockup control. Control is started from an arbitrary initial differential pressure Po between and. Thereby, for example, the learning can be completed earlier than when the control is started from the maximum initial differential pressure Max as in the prior art (corresponding to the invention described in claim 1).
[0063]
Next, it is determined whether the slip amount Slip is larger than the slip amount Slip1 (corresponding to the second slip amount described in the claims) representing the abnormal slip amount, and when the abnormal slip amount has not occurred, Even if there is an inherent difference between the automatic transmission units, it is determined that an engagement differential pressure that does not cause a problem in learning control can be obtained. Then, using this initial differential pressure as a starting differential pressure, the lockup clutch 2 is locked 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 used as a learning value. A preset offset differential pressure is obtained to this learning value so as to obtain a fastening force that prevents the lockup clutch 2 from slipping, and this (learning value + offset differential pressure) is added to the initial value at the next coast lockup control. Set as differential pressure. This makes it possible to set the lock-up clutch engagement force to a marginal value, improving the fuel efficiency and allowing the lock-up clutch to slip even if a large torque is input from the drive wheels due to sudden deceleration, etc. Engine stall can be prevented (corresponding to the inventions of claims 1 and 2).
[0064]
FIG. 7 is a time chart when the first coast lockup control is determined in step 201 and an abnormal slip occurs. If the initial differential pressure Po is set in step 201 and step 202 and it is determined that an abnormal slip has occurred, it is determined in step 210 whether or not it is in a sudden deceleration state. If the rapid deceleration state has not been detected at this stage, it is determined whether a predetermined time has elapsed. If the abnormal slip amount is detected even after the predetermined time has passed and abnormal slip is determined for some reason other than sudden deceleration, the maximum initial differential pressure Max is set as the initial reset differential pressure, and the maximum initial differential pressure is set as the initial differential pressure. Learning control is started from the differential pressure Max.
[0065]
FIG. 8 is a time chart when the coast lockup control is performed a plurality of times and an abnormal slip occurs. If it is determined that the coast is in a state where the accelerator is released, coast lock-up control is executed. At this time, when the brake is stepped on, 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, when Slip1, which is a determination value of the abnormal slip amount, is exceeded, a timer is counted. Here, the slip amount is calculated from the difference between the engine rotational speed and the turbine rotational speed (primary rotational speed). In general, the engine rotational speed update period is longer than the turbine rotational speed update period. In this state, if the wheel is locked due to sudden deceleration, the turbine speed may be extremely reduced with the engine speed being high due to the delay in the update period of the engine speed, and the slip amount is extremely large. There is a risk of misjudging it. Therefore, it is possible to prevent an erroneous determination by determining an abnormal slip only when the abnormal slip continues for a predetermined time (corresponding to the invention described in claim 4).
[0066]
If a sudden deceleration determination is made at time t3 while the timer is being counted, the routine proceeds to lockup OFF control. In other words, if it is a sudden deceleration state, the sudden deceleration state is detected within a predetermined time counted by the timer, so the routine proceeds to step 213 and lockup OFF control is executed. Therefore, the process does not proceed to step 205 to step 208, and erroneous learning is not performed (corresponding to the inventions according to claims 3 and 4). Further, even if a predetermined time has elapsed at time t4 and an abnormal slip determination is made, the learning value is not reset, so a high engagement differential pressure that is reset at the next coast lockup control is set. There is no problem, and it is possible to avoid problems such as lockup OFF shock and engine stall.
[0067]
(Other embodiments)
As mentioned above, although the embodiment based on the embodiment has been described, the specific configuration is not limited to this embodiment, and does not depart from the gist of the invention according to each claim of the claims. As long as the design is changed or added, it is allowed.
[Brief description of the drawings]
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 showing lock-up control in the first embodiment.
FIG. 5 is a flowchart showing coast lock-up control in the first embodiment.
6 is a diagram showing the relationship between the number of coast lockups and the initial differential pressure when abnormal slip does not occur in Embodiment 1. FIG.
7 is a diagram showing the relationship between the number of coast lock-ups and the initial differential pressure when an abnormal slip occurs in Embodiment 1. FIG.
FIG. 8 is a time chart showing switching from coast lockup control to lockup control during sudden deceleration in the first embodiment.
[Explanation 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 Sungear
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 Driven shaft
40 pressure regulator valve
45 Orifice
50 Pilot valve
60 Clutch regulator valve
70 Select switching 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 fastening force;
Slip amount detecting means for detecting the slip amount of the lockup clutch from the engine speed and the turbine speed;
Traveling state detection means for detecting at least the throttle opening and the vehicle speed;
When it is determined from the detected throttle opening and vehicle speed that the coasting state in which torque is input from the drive wheel side is applied, an initial differential pressure is applied, and a control differential pressure that is equal to or less than a preset first slip amount is set. Coast lockup control means for outputting,
Initial differential pressure learning means for gradually changing the initial differential pressure in the release direction according to the number of coast lockups, and learning until the control differential pressure is reached;
In a lockup control device for an automatic transmission unit comprising:
The lower 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 upper limit value of the initial differential pressure that surely 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,
The initial differential pressure learning means sets the initial differential pressure to the maximum when the slip amount detected when the initial differential pressure initial value is set 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 lockup control device for an automatic transmission. In the automatic transmission lockup control device according to claim 1,
The coast lockup control means includes a slip lockup differential pressure learning unit that learns a slip lockup differential pressure for maintaining the first slip amount, and the learned slip lockup differential pressure includes the slip lockup differential pressure. A lockup control device for an automatic transmission, wherein a value obtained by adding an offset differential pressure that is less than one slip amount is output as a control differential pressure. The automatic transmission lockup control device according to claim 1 or 2,
A rapid deceleration detection means for detecting whether the vehicle is in a sudden deceleration state,
The automatic differential lockup control device, wherein the initial differential pressure 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 where 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 lockup control device for an automatic transmission.

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