JPH0330022B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a control device for an automatic transmission, and more particularly to a control device for a lock-up clutch that directly connects the input and output shafts of a torque converter. A torque converter usually includes a pump impeller, a turbine runner, and a stator disposed between them, and circulates hydraulic oil from the engine-driven pump impeller, and directs the hydraulic oil discharged from the turbine runner at an appropriate angle. The octopus stator allows the pump to be inserted smoothly from a direction that does not interfere with the rotation of the pump impeller, and by repeating this operation without reducing the speed of the circulating hydraulic oil,
Torque is increased by increasing the reaction force of the turbine runner. Torque converters have an automatic speed change function in which the torque increase is large when the turbine rotation speed is low compared to the pump rotation speed, but the torque increase becomes smaller as the turbine rotation approaches the pump rotation speed. However, a drop in power transmission efficiency due to slip between the pump and the turbine cannot be avoided, resulting in poor fuel efficiency. In order to eliminate this slip and reduce efficiency, recently a direct coupling or lock-up clutch has been installed to directly connect the input shaft and output shaft of the torque converter. It has been proposed to perform lock-up control that directly connects the pump and turbine. However, in this locked-up state, the function of the torque converter is not utilized, so there is a problem in that a shift shock occurs if a shift is performed in the locked-up state. In order to solve this problem, Japanese Patent Application Laid-Open No. 56-39354
This publication proposes a lock-up control method in which lock-up is released at the time of gear change, and gear change is performed a predetermined time after the lock-up is released.
However, the transmission mechanism of an automatic transmission is usually composed of a multi-stage gear mechanism that uses a planetary gear mechanism and has a plurality of gear stages, and the required gear stage is changed by appropriately operating attached friction elements such as clutches or brakes. These clutches, brakes, etc. wear out with repeated use, and the time required to shift gears increases with use.
In the lock-up control method described in the above-mentioned Japanese Patent Application Laid-open No. 56-39354, when the clutch etc. of an automatic transmission becomes worn, the gear change is not completed while the lock-up is released, and the gear change is performed after the lock-up is released again. This situation occurs, and the gear shift shock comes out. SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a lock-up control device for an automatic transmission that can solve the above problems and provide stable lock-up control even when the clutch etc. are worn out. The configuration of the present invention includes a torque converter and a multi-stage gear transmission mechanism having a plurality of gears selected by the operation of a friction element, and the torque converter includes a lock-up clutch that connects an input member and an output member of the torque converter. is provided with a vehicle speed sensor that detects a vehicle speed signal, an accelerator depression amount sensor that detects the amount of accelerator depression, and a predetermined shift signal based on the signals from these two sensors to control the friction element. and a lock-up off means that releases the lock-up until a predetermined time has elapsed from the generation of the shift signal when lock-up is being performed. A slip detection means detects the slip of the friction element from the vehicle speed and engine rotational speed, and a slip signal from the slip detection means lengthens the above predetermined time, thereby lengthening the lock-up-off time during subsequent gear changes. The present invention is characterized in that it includes a lockup-off time correction means. In addition, the above-mentioned slip time detection means detects the slip of the friction element and detects the time from generation of the shift signal until the above-mentioned slip disappears, and the above-mentioned predetermined time is updated based on the slip signal from the slip time detection means. It is also possible to provide a lockup-off time correction means that sets the lockup-off time to . According to the present invention, when the friction elements such as the clutch of the transmission mechanism wear out and the time required for shifting becomes longer, and the transmission operation is not completed within the lock-up off time, this is detected by the slippage of the friction elements. Then, since a correction is made to lengthen the lockup-off time, the problem of lockup being performed again before the shift is completed will no longer occur from the next operation.
Therefore, satisfactory lock-up control can be provided even after the clutch etc. have worn out, and the occurrence of shift shocks can be kept to a minimum. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of an automatic transmission according to an embodiment of the present invention, and this automatic transmission includes a torque converter 1
0, a multi-stage gear transmission mechanism 20, and an overdrive planetary gear transmission mechanism 50 disposed between the torque converter 10 and the multi-stage gear transmission mechanism 20. The torque converter 10 includes a pump 11 coupled to an engine output shaft 1, a turbine 12 disposed opposite the pump 11, and a stator 13 disposed between the pump 11 and the turbine 12. A converter output shaft 14 is coupled to 12 . A lock-up clutch 15 is provided between the converter output shaft 14 and the pump 11. This lock-up clutch 15 is constantly pushed in the engagement direction by hydraulic pressure circulating within the torque converter 10, and is held in the released state by release hydraulic pressure supplied to the clutch 15 from the outside. The multi-stage gear transmission mechanism 20 includes a front planetary gear mechanism 2
1 and a rear planetary gear mechanism 22, and a sun gear 23 of the front planetary gear mechanism 21 and a rear planetary gear mechanism 22.
It is connected to the sun gear 24 by a connecting shaft 25. The input shaft 26 of the multi-stage gear transmission mechanism 20 is connected to the connecting shaft 25 via a front clutch 27 and to the internal gear 29 of the front planetary gear mechanism 21 via a rear clutch 28, respectively. The connecting shaft 25, that is, the sun gear 23,
24 and the transmission case is the front brake 30.
is provided. The planetary carrier 31 of the front planetary gear mechanism 21 and the internal gear 33 of the rear planetary gear mechanism 22 are connected to an output shaft 34, and a rear brake 36 is connected between the planetary carrier 35 of the rear planetary gear mechanism 22 and the transmission case.
A one-way clutch 37 is provided. The overdrive planetary gear transmission mechanism 50 is
A planetary carrier 52 that rotatably supports a planetary gear 51 is connected to the output shaft 14 of the torque converter 10, and a sun gear 53 is connected to an internal gear 55 via a direct coupling clutch 54. An overdrive brake 56 is provided between the sun gear 53 and the transmission case, and the internal gear 55 and the multi-gear transmission mechanism 20 are connected to the input shaft 26. The multi-gear transmission mechanism 20 is of a conventionally known type and has three forward speeds and one rear speed.
28 and the brakes 30 and 31 as appropriate, a desired gear stage can be obtained. The overdrive planetary gear transmission 50 connects the shafts 14 and 26 in a direct connection state, when the direct coupling clutch 54 is engaged and the brake 56 is released, and when the brake 56 is engaged and the clutch 54 is released. Shafts 14 and 26 are coupled in overdrive. Further referring to FIG. 1, the automatic transmission of this example has a hydraulic control circuit. In this control circuit, the pressure of hydraulic oil discharged from the oil pump 100 driven by the engine output shaft to the pressure line 101 is adjusted by the pressure regulating valve 102, and the pressure is adjusted by the select valve 103.
guided by. The select valve 103 is 1, 2, D,
The pressure line 10 has shift positions N, R, and P, and when the select valve is in the 1, 2, and P positions, the pressure line 10
1 communicates with ports a, b, and c of the valve 103. Port a is connected to an actuator 104 for actuating the rear clutch 28, which is held engaged when the valve 103 is in the position described above. Also, port a is the 1-2 shift valve 11
0, pushing this spool to the right in the figure. Port b is also connected to second lock valve 105 via line 140, and this pressure acts to force the spool of valve 105 downward in the figure. When the spool of valve 105 is in the down position, lines 140 and 14
1 are in communication with each other, and hydraulic pressure is introduced into the engagement side pressure chamber of the actuator 108 of the front brake 30 to hold the front brake 30 in the operating direction. Port c is connected to second lock valve 105, and this pressure acts to push the spool of valve 105 upward. Further, port e is connected to a 2-3 shift valve 120 via a pressure line 106, which is connected to a solenoid 120a of the valve 120.
is excited and its spool moves to the left, it communicates with the line 107, and the line 107 is connected to the release side pressure chamber of the actuator 108 of the front brake 30, and when hydraulic pressure is introduced into the pressure chamber, the actuator 108 operates the brake 30 in the releasing direction against the pressure in the engagement side pressure chamber.
Also, the pressure in line 107 is
actuator 109 to engage this clutch 27. The select valve 103 has a port d leading to the pressure line 101 in one position, and this port d
passes through line 112 to the 1-2 shift valve 110, and further passes through line 113 to the rear brake 36.
is connected to the actuator 114 of. The 1-2 shift valve 110 and the 2-3 shift valve 120 are electromagnetic valves, and the solenoids 110a and 1 are activated by a predetermined signal.
When 20a is energized, the spool is moved to switch lines, thereby operating a predetermined brake or clutch to perform a 1-2 or 2-3 speed change operation, respectively. In addition, the control circuit includes a cutback solenoid valve 115 that stabilizes the oil pressure from the pressure regulating valve 102, a downshift solenoid valve 116 for kickdown, and a pressure regulating valve 115 that controls the pressure regulating valve 102 according to the magnitude of the intake negative pressure.
A vacuum throttle valve 117 for changing the line pressure from 3, and a throttle backup valve 118 for assisting this throttle valve 119 are provided. Additionally, the control circuit of this example includes a 3-4 shift solenoid valve 130 and an actuator 132 for controlling the clutch 54 and brake 56 of the overdrive planetary gear transmission 50. The engagement side pressure chamber of the actuator 132 is connected to the pressure line 101.
The brake 56 is pushed in the engagement direction by the pressure of 01. When the solenoid 130a of the 3-4 shift electromagnetic valve 130 is energized, the spool 131 of the valve 130 moves downward, the pressure line 101 and the line 122 communicate with each other, and hydraulic pressure is introduced into the line 122. The hydraulic pressure introduced into this line 122 acts on the release side pressure chamber of the actuator 132 of the brake 56, actuating the brake 56 in the release direction, and at the same time actuating the actuator 131 of the clutch 54.
acts to engage clutch 54. Furthermore, the control circuit of this example includes a lock-up solenoid valve 1.
33 is provided, and the solenoid 133 of the valve
When a is energized, hydraulic pressure in pressure line 101 is introduced into line 124 through line 123, moving lock-up clutch 15 in the releasing direction. The table below shows the operational relationship between each gear, clutch, and brake in the above circuit.

[Table] Referring to FIG. 2, an example of a circuit related to lockup control of the present invention is shown. A signal from the vehicle speed sensor 200, ie, a signal W ₀ representing the rotational speed of the output shaft of the transmission, is input to the speed change control circuit 201. This shift control circuit 201 receives a signal A from an accelerator depression amount sensor 202.
The shift control circuit 201 calculates an appropriate gear stage from the above two signals W ₀ and A, and outputs shift signals S1, S2, and S3. This signal S1,
S2 and S3 are a solenoid 110a for the 1st-2nd speed control valve and a solenoid 12 for the 2nd-3rd speed control valve, respectively.
It is sent to the solenoid 130a for the 0a, 3rd and 4th speed control valves, controls the excitation and demagnetization of these solenoids, and provides a gear position according to the calculation result of the shift control circuit 201. Further, signals S1, S2, and S3 from the gear shift control circuit 201 are input to the gear stage detection circuit 203. This gear stage detection circuit determines whether or not a gear shift has been carried out, and if a gear shift has been carried out, it is 1;
If there is no speed change, a signal S4 of 0 is generated. The signal W ₀ from the vehicle speed sensor 200 and the signal A from the accelerator depression amount sensor 202 are also input to the lock-up control circuit 204, and the lock-up control circuit 204 receives these two signals W ₀ and A as shown in FIG. 3, for example. It performs arithmetic processing according to the normal lockup line or power lockup line, and generates a lockup signal S5 which is 1 when lockup is to be performed and 0 when it is not.
This signal is input to multiplier 205. Multiplier 2
The output S4 of the gear stage detection circuit 203 is also input to 05, and this multiplier 205 outputs a signal S of 1 when both signals S4 and S5 are 1, and 0 otherwise.
This signal S6 is input to the lockup-off circuit 206. Lock up-off circuit 2
06 is the previous state memory 207 when the signal S6 is 1.
A signal S7 of 0 is output for the time T _o0,t-1 stored in . This signal S7 is input to multiplier 208. The multiplier 208 includes a lockup control circuit 2.
Signal S5 from 04 is also input, and signals S5 and S
A signal S8 which is 1 when 7 is 1 and 0 otherwise is output, and the signal S8 controls the excitation and demagnetization of the solenoid 133a of the lock-up solenoid valve 133. Therefore, when changing gears while lock-up is being performed, the lock-up off circuit 206 is activated.
Since the output of is 0 for a predetermined time T _o0,t-1 , the signal S8 becomes 0 during this time, and the solenoid 133a of the lock-up solenoid valve is demagnetized and the lock-up is stopped.
It is held in the released state for T _o0,t-1 time. The output signal S4 of the gear stage detection circuit 203 is also input to the _to setting circuit 209, and the _to setting circuit receives the signal S4.
When S4 is 1, a signal t _o ≠0 is generated corresponding to an appropriate length of time depending on the gear position, and when signal S4 is 0, a signal t _o =0 is generated. This signal _to is added to the adder 21
It is input to 0. A signal T _o0,t-1 representing the time stored in the previous state memory 207 is also input to the adder 210, and the adder 210 adds the two to generate a signal.
Output T _o0,t-1 +t _o . This signal T _o0,t-1 +t _o is input to the gate circuit 211 . Gate circuit 211
is a multiplier 212 that receives signals S4 and S5 as inputs.
is open when the output S9 is 1, and the signal T _o0,t-1 +t _o
is input to the clock timer 213. The clock timer 213 inputs the circuit start pulse S10 to the divider 214 with a delay of T _o0,t-1 +t _o time. Apart from this, the divider 214 also receives a signal W _E from the engine speed sensor 215 and a signal W E from the vehicle speed sensor 20.
A signal W ₀ from 0 is input. Divider 21
4 is the output signal W _E /W ₀ when the circuit start pulse S10 from the clock timer 213 is input.
is generated and input to the comparator 216. On the other hand, the signal S4 from the gear position detection circuit 203 is input to the reduction ratio setting circuit 217, and the reduction ratio setting circuit 217 outputs a signal i _o representing the reduction ratio of the gear position. This signal i _o is also input to comparator 216 . Comparator 21
6 compares the signal W _E /W ₀ and i _o when the circuit start pulse S10 is input, and when W _E /W ₀ = i _o , it is 0, and when W _E /W ₀ ≠ i _o , it is 1. A signal S11 is generated. This signal S11 is transmitted by the potentiometer 218
and is input to the inverter 219. When the signal S11 is 1, the potentiometer 218 is Δt _o =k(k
>0), and when the signal S11 is 0, a time signal Δt _o with Δt _o =0 is output. The value of k can be arbitrarily set by changing the resistance value of the potentiometer. The signal Δt _o is input to the adder 220 after being held in a holder for a certain period of time. The adder 220 also receives a signal T _o0,t-1 of the currently occurring lockup-off time stored in the previous state memory 207, and the adder 220 calculates the time T _op,t that is the sum of these signals. Output. This signal is input to gate circuit 221. Gate circuit 221
becomes open when the output S11 of the comparator 216 becomes 0 and the output S12 of the inverter 219 becomes 1, and outputs the input signal. In this case, when W _E /W ₀ / _io when the circuit start pulse S10 is input to the divider 214 and the comparator 216, the output S11 of the comparator 216 continues from before the circuit start pulse S10 is input. is maintained at 0, and the potentiometer output Δt _o is 0.
Therefore, the output of the retainer 230 is also 0.
The output of the adder 220 is T _o0,t =T _o0,t-1 , which is stored in the previous state memory through the gate circuit in the open state. Therefore, the lockup-off time is not corrected in this case. Further, when the output of the divider W _E /W ₀ ≠ _io , it means that there is still slippage in the gear shift clutch, etc., and the output S11 of the comparator 216 is 1. Therefore, the output from the potentiometer is Δt _o =k
This value is temporarily held in the holder 230 and then input to the adder 220. Therefore, the output of adder 220 is T _o0,t = T _o0,t-1 + Δt _o . After this, as time passes and the slippage disappears,
W _E /W ₀ = i _o , and the output S11 of the comparator 216
changes to 0, and the output S12 of the inverter 219 changes to 1, holding the outputs of the divider 214 and the comparator 216 at 0, and is input to the gate circuit 221 to open the gate circuit 221. At this time, the output S11 of the comparator 216 has changed to 0, but the state when the signal S11=1 is held by the holder 230, so the signal T with the relationship T _o0,t-1+ 〓 _{to o0,t} passes through the gate circuit 221 and is newly stored in the previous state memory 207. This means that the lockup-off time has been corrected. In addition, in FIG. 2, the speed change control circuit and the lock-up control circuit can also be constructed by a microcomputer. Referring to FIG. 4, a circuit of another embodiment of the present invention is shown. In this example, potentiometer 2
18 is replaced by a timer 222, the circuit start pulse S10 is input to the divider 214, the divider 214 outputs the signal W _E /W ₀ , and the timer 222 is set until the output S12 of the comparator 216 becomes 1. The time, that is, the time until the difference between the engine rotational speed and the vehicle speed, that is, the rotational speed of the transmission output shaft disappears, is measured, and a time signal Δt ₁ corresponding to the time is output. This time Δt ₁ is the current lockup-off time
T _o0,t-1 is added, and the lockup-off time is corrected in the same manner as in the previous embodiment. Therefore, the next time this control is performed, the corrected lockup-off time, ie, T _o0,t is applied. At the same time, this newly set lockup-off time T _o0,t is subject to correction during the next control. Therefore, the appropriateness of the lock-up off time is determined every time a gear change is performed in the lock-up state, and the optimum lock-up off time is always selected. Referring to FIGS. 5 to 7, flowcharts are shown in which the above-mentioned lockup control circuit is constructed by a microcomputer. In this case, the controls shown in FIGS. 5 and 6 are the same as those in the embodiment shown in FIG. 2, and the controls shown in FIGS. Since this is the same as the control content, detailed explanation will be omitted. Referring to FIG. 8, an example of lockup control according to the present invention is shown. FIG. 8a shows an example of lock-up control when the speed change clutch etc. are not worn out. As shown in the figure, the shift operation is completed within the initially determined lockup time _T0 , and no shift shock occurs. On the other hand, FIG. 8b shows an example of control when the speed change clutch etc. are worn out. As shown in the figure, when the clutch etc. wear out, the time required for the gear shifting operation becomes longer, and the set time T ₀ shown by A increases.
The gear shifting operation will not be completed within a few seconds, and the gear shifting will occur. In the control according to the present invention, once such a state is experienced, a correction time _t1 is added to the set time _T0 , and a lock-up-off release command, that is, a re-lock-up command is issued after _T0 + _t1 time has elapsed. As shown, the re-lockup is performed after the shift operation is completed, thereby preventing a shift shock.

[Brief explanation of drawings]

FIG. 1 is a sectional view and hydraulic control circuit diagram of an automatic transmission according to an embodiment of the present invention, FIG. 2 is a control circuit diagram according to an embodiment of the present invention, and FIG. 3 is a graph showing a lock-up line. FIG. 4 is a control circuit diagram of another embodiment, FIGS. 5 to 7 are examples of flowcharts when the control of the present invention is performed by a microcomputer, and FIG. 8 is a graph showing an example of control according to the present invention. . Explanation of symbols, 10...Torque converter, 11
...Pump, 12...Turbine, 15...Lock-up clutch, 30...Front brake, 54...
...Direct coupling clutch, 110...1-2 speed change control valve,
120...2-3 speed change control valve, 130...3-4
Shift control valve, 133... lock-up control solenoid valve, 200... vehicle speed sensor, 202... accelerator depression amount sensor.

Claims (1)

[Scope of Claims] 1. A torque converter and a multi-gear transmission mechanism having a plurality of gears selected by the operation of a friction element, and the torque converter includes a lock that connects its input member and output member. The up clutch is equipped with a vehicle speed sensor that detects a vehicle speed signal, an accelerator depression amount sensor that detects the amount of accelerator depression, and generates a predetermined shift signal based on the signals from these two sensors. a speed change control means for operating the friction element;
In an automatic transmission provided with a lock-up off means for releasing the lock-up until a predetermined time has elapsed from the generation of the shift signal when the lock-up is being performed, the vehicle speed and the engine rotational speed are slip detection means for detecting slip of the friction element from;
An automatic transmission characterized by comprising lock-up-off time correcting means for lengthening the predetermined time based on a slip signal from the slip detecting means, so that the lock-up-off time during subsequent gear changes becomes longer. 2. A torque converter and a multi-gear transmission mechanism having a plurality of gears selected by the operation of a friction element, wherein the torque converter is provided with a lock-up clutch that connects its input member and output member, and the transmission mechanism is configured to change speed. For control, there is a vehicle speed sensor that detects a vehicle speed signal, an accelerator depression amount sensor that detects the amount of accelerator depression, and a shift that operates the friction element by issuing a predetermined shift signal based on the signals from these two sensors. In an automatic transmission provided with a control means and a lock-up off means for releasing the lock-up until a predetermined time has elapsed from generation of the shift signal when the lock-up is being performed, the vehicle speed is a slip time detection means for detecting the slip of the friction element based on the engine rotational speed and detecting the time from generation of the shift signal until the slip disappears; and a slip time detection means for detecting the slip of the friction element based on the engine speed; Automatic transmission with lock-up-off time correction means to set.