JPS58128552A - Creep preventing apparatus for automatic transmission - Google Patents

Abstract

PURPOSE:To prevent a vehicle from running forward at a low speed at the time of idling operation of an engine, by reducing the line pressure applied to a forward travelling servomotor when no load is acted to the engine and the vehicle is stopped. CONSTITUTION:Automatic changing of speed is effected by controlling the hydraulic pressure through shifting of a speed selector valve 130. When the speed selector valve 130 is shifted to forward travelling positions (D, II,I), a line pressure is applied directly to a forward travelling frictional element 105. Subsequently, if no load is acted to the engine and the vehicle is stopped, the line pressure is reduced to a level of the instant just before the frictional element 105 is coupled by the function of orifices 206, 208 and a solenoid valve 210. Therefore, it is enabled to start the vehicle without any trouble and to prevent occurrence of creep at the time of idling operation of the engine.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a creep prevention device for an automatic transmission.

For automatic transmissions, the driver moves the speed selection hole to the park (P) position.

Manually move to each position such as reverse travel (R) position, neutral (N) position, forward automatic shift travel (D) position, forward 2nd speed fixed travel (Fl) position, and 1st forward speed fixed travel (I) position. By operating the vehicle, desired parking/stopping and driving conditions can be obtained.

The automatic transmission has the speed selection hole in the forward travel position (D above).
%■or! A forward gear is provided with a forward friction element that is supplied with line pressure and engaged when the vehicle is in a position (position), and a predetermined forward gear is set depending on the driving condition by a combination of engagement of the forward friction element and engagement or release of other friction elements. It can be selected automatically〇However, automatic transmissions can transmit power to the vehicle drive wheels with the speed selection hole in the forward travel position.

If you release the brake, the engine will idle (
Even when the vehicle is under no load (no load), it cannot escape the creep that causes the vehicle to move forward at a very slow speed.

If a car equipped with this automatic transmission comes to a stop while still in the forward running position, the brakes must be applied.
In this stationary state, the engine is subject to a creep load. Also, this causes the engine's rotational speed to drop, making concave rotation uneven and causing vibrations, so by taking into account this reduction, the engine of a car equipped with an automatic transmission will change its idling rotational speed to the same speed as that of a car equipped with a manual transmission. Coupled with the need to set the temperature higher than the engine, this results in poor fuel efficiency and overheating, especially when using a cooler in the summer.

Therefore, various creep prevention measures for automatic transmissions have been devised. One is used in electronically controlled automatic transmissions, which detects the idling state in the D position, leaves the automatic transmission in the highest gear selected, and creeps by the amount of the small reduction ratio. This is a measure to reduce the

However, since this measure does not completely cut off power transmission, the problem of creep remains, and a perfect solution is impossible. In addition, with this measure, when depressing the accelerator pedal to start, it is necessary to return the automatic transmission to the first gear selection state, and the automatic transmission must be changed to the first gear while the engine speed is increasing due to depressing the accelerator pedal. This is because the shock during this gear shift is unexpectedly large, and as a countermeasure to prevent creep, which impairs the ride comfort of the vehicle.
As described in Japanese Patent No. 6-89848, the line pressure supplied to the forward movement friction element is reduced in the idling state at the D position so that the friction element is not engaged.

There is a system that prevents the occurrence of creep by interrupting power transmission, and stops reducing the line pressure when the accelerator pedal is depressed, making it possible to start the vehicle. Although this measure can solve the problems of the above measures, if you switch the speed selection valve from the N position to a forward travel position such as the D position and immediately try to start by depressing the accelerator pedal, at this time as well, the forward friction element initially Since the incoming line pressure is supplied through the pressure reduction path, there is a time lag in the engagement of the friction elements, and prior to this engagement, the engine runs dry, resulting in poor fuel efficiency and a shock upon starting.

The present invention follows most of the latter creep prevention measures, but at 9 o'clock the speed selector valve is switched from the neutral position to the forward travel position, the line pressure is initially supplied as is to the forward friction I [element, and then the engine is in a no-load state. and when the vehicle is stopped, the line pressure supplied to the forward friction element is reduced so that the forward friction element is maintained in the state immediately before engagement, and the speed selection valve is changed from the neutral position to the forward travel position. When starting by immediately pressing the accelerator pedal after switching to J!
The present invention aims to provide a creep prevention device for automatic transmissions that can prevent the occurrence of creep in the same way as the latter measure without causing the inconvenience of a time lag in the engagement of JIJs elements. The present invention will be described in detail based on Examples.

FIG. 1 is a schematic diagram of a power transmission section illustrating an automatic transmission to which the creep prevention device of the present invention is applied. This power transmission section includes a crankshaft 4 driven by a torque e-converter 7. Front clutch 104. Rear clutch CM
forward friction element) 105, second brake 106, low Φ reverse brake 107, one-way brake 108
, intermediate shirt) 109, first planetary gear group 110. 2nd planetary gear group Ill, output shaft 7) ttg.

First governor valve 118. It is composed of a second governor valve 114 and an oil pump 18. torque converter l
consists of a pump impeller 8, a turbine impeller 8%, a stator impeller 9, and the pump impeller 8 is driven by the crankshaft noise and rotates the torque converter hydraulic oil contained therein to connect the turbine fixed to the input shaft 7. Give torque to the impeller 8. Torque is directly transmitted to the transmission gear train by the input shaft 7. Stator wheel 9 is placed on sleeve 12 via one-way clutch lO. The one-way clutch lO has a structure that allows the stator wheel 9 to rotate in the same direction as the crankshaft 4, that is, in the direction of the arrow (hereinafter referred to as forward rotation), but does not allow rotation in the opposite direction (hereinafter referred to as reverse rotation). ing. The first planetary gear group 110 is fixed to the intermediate shaft 109! 1111
Single 11th.

a sun gear 119 fixed to the inner wall conduction shirt 118;
A planetary gear 120 consisting of two or more small gears that can rotate and revolve simultaneously while meshing with each of the internal gear 117 and the sun gear 119, and a planetary gear support 12 that is fixed to the outgoing shaft 112 and supports the planetary gear 120.
1, the second planet-table group ill is fixed to the output shaft l12, and the l11m wheel 122. A planetary gear 124 consisting of two or more small gears that can rotate simultaneously with the sun gear 128, an internal gear 122, and a sun gear 128 fixed to the intermediate transmission gear 7) 118 and rotate at the same time as the sun gear 128. It is composed of a supporting planetary gear support 125. front clutch 10
4 connects, via a drum 126, an input shaft 7 driven by a turbine impeller 8 and a medium 2E shaft 118 which rotates integrally with both thick #1 tooth tables 119 and 128, and a rear clutch 105. It serves to connect the input shaft 7 and the internal gear 117 of the first planetary gear $110 via the intermediate shaft 109. The second brake 106 is made by winding and tightening the drum 126 fixed to the internal conduction shaft 118.
19,128 fixed, low reverse brake 10
7ti second game! 1 gear group 111 planet-wheel support body 1sz
It works to fix t. The one-way brake 108 has a structure that allows the planetary gear support 125 to rotate in the normal direction, but not in the reverse direction. The first governor valve 11δ and the second governor valve 114 are fixed to the output shaft 112 and generate a negative governor pressure depending on the vehicle speed. Next, move the speed selection rod to D(f
The power transmission train in the case where the automatic transmission is set to the [FA advance automatic transmission] position will be explained.

In this case, only the rear control clutch 105, which is the forward input clutch, is initially engaged. The power from the engine via the torque converter l is input to the internal gear 11.
7 causes the planetary gear 120 to rotate normally. Therefore, the sun gear 11
9 rotates in reverse, and the planetary gear 124 of the second planetary gear group ill rotates in the normal direction, which reverses the sun gear 128 of the second planetary gear group ill, which rotates integrally with the sun gear 119. One-way brake 108 prevents sun gear 12δ from reversing planetary gear support 125 and acts as a forward reaction brake. Therefore, the I*I granite 122 of the second planetary tooth table group 111 rotates normally. Therefore, the output shaft 112, which rotates integrally with the internal gear 122, also rotates in the normal direction, and the reduction ratio of the first forward speed is obtained.

In this condition, the vehicle speed increases and the second brake
6 is engaged, power from the input shaft 7 passing through the rear clutch 105 is transmitted to the internal gear 117 as in the case of the first speed. The second brake 106 fixes the drum 126, prevents the rotation of the thick gear 119, and functions as a forward reaction brake. For this reason, the planetary gear 120 revolves around the stationary sun gear 119 while rotating on its own axis, and therefore the planetary gear support 121 and the output shaft 11g integrated therewith are decelerated, but in the first speed. It rotates forward at a higher speed than the normal speed, and the reduction ratio of the second forward speed is obtained. Furthermore, the vehicle speed increases and the second
When the brake 106 is released and the front clutch 104 is engaged, the power transmitted to the input shaft 7 is transferred to the internal gear 117 via the rear clutch 105.
transmitted to.

The other one is connected to the sun gear 119 via the front clutch 104.
transmitted to. Therefore, the inner 111111jltl17 and the sun wheel 119 are interlocked, and the planetary gear support 1
21 and output shirt) 11g, all rotate forward at the same rotational speed to obtain the 8th forward speed. in this case,
The input clutch corresponds to front clutch 10.
4 and the rear clutch 105, and the torque is not increased by the planetary gear, so the reaction brake does not act.

FIG. 2 shows the hydraulic system of the speed change control device of the automatic transmission, including the oil pump 13. Line pressure adjustment square 12
8. Pressure increaser 129, torque converter 11 selection speed 1
80, 1st governor square 11'l.

Second governor valve 114.1-2 shift box 181°2-8
Shift ff182, throttle pressure reduction yPiaa, cut down 134, second lock valve 185, Q-8
Timing ff186, solenoid down shift f
f187, throttle back 'y Pias,
Vacuum e-throttle box 189, vacuum diaphragm 140, front φ clutch 104, rear clutch 105. Second brake 106, servo 141
．． Consists of low reverse fist brake 107 and hydraulic circuitry. The oil fist pump 18 is driven by the prime mover through the crankshaft number and the pump wheel 8 of the torque converter 1, and the oil pump 18 is always in the reservoir 14g during engine operation.
The oil from which harmful dust has been removed is sucked up through the strainer 148 and sent to the line pressure circuit 144. The oil is brought to a predetermined pressure by the line pressure A adjustment ff 128.
Torque converter i as hydraulic pressure
and 0 lie/pressure adjustment box 128 sent to speed selection box 180
consists of school 112 and spring 178, and school 17
In addition to spring 178, school 1 of pressure increase yP129 is added to 2.
The throttle pressure of the circuit 165 and the line pressure of the circuit 156 act through the circuit 144 above the school 172.
o torque acting against line pressure acting through orifice 175 and pressure acting from circuit 176.
The working oil pressure of the converter l is determined by the hydraulic torque and torque input from the circuit 144 to the circuit 146 via the 2-inch pressure adjustment tank TGS.
This occurs when the pressure holding valve 146 is opened after flow to the converter 1, and is maintained within a certain pressure by the pressure holding valve. Above a certain pressure, the pressure holding valve 146 is opened and the oil is further transferred to circuit 1.
47 to the rear lubrication section of the power transmission mechanism. When this lubricating oil pressure is too high, the relief 9f148 opens and the pressure is lowered.On the other hand, the front lubricating part 149 of the excitation power transmission mechanism is supplied with lubricating oil from the circuit 145 by opening the front lubricating part 149.0 speed Valve 180 is a manually operated fluid directional valve and is constituted by spool 150.

Connected to a speed selection rod (not shown) via a linkage, the school 150 is moved by each speed selection operation and the line pressure circuit 1 is connected to the speed selection rod (not shown).
44 pressure feeding passages.

The condition shown in FIG. 2 is the N (neutral) position in which the line pressure circuit 144 is open to boats d and . The first governor cell 118 and the second governor cell 114 shift l-2 pi 81. due to the governor pressure generated during forward travel. and 2-8 shift) It operates ff132 to perform automatic gear shifting and also controls line pressure, and when it is in the gear selection, 7180, II, and I positions,
Hydraulic pressure is from the line pressure circuit 144 to the boat 0 of the speed selector ISO.
When the car runs, the governor pressure regulated by the second governor cell 114 is sent to the circuit 157 and introduced into the first governor cell 118. When the vehicle speed reaches a certain speed, the governor pressure is regulated by the second governor cell 114. school 1
77 moves, the circuit 157 becomes conductive with the circuit 158, and governor pressure is generated, and the governor pressure from the circuit 158 becomes l-
2-shift square 181° 2-8 shift 7182 and cut-down ff 184 are balanced by springs that act on each end face and press these six squares to the right. Father, circuit 1581 circuit 161 from boat C of selection speed 180
1-277) ffl 81 and a second lock valve 135 are separately provided in the middle of the hydraulic circuit that reaches the engagement side hydraulic chamber 169 of the servo 141 that tightens the second O brake 106 via the circuit 162, and the speed selection box 180. Circuit 1 from boat b to second lock valve 185
52 is provided.

Therefore, when the speed control rod is set to the D position, the spool 150 of the speed control 180 moves and the line pressure circuit 144 is turned off.
, b, and 0. Hydraulic pressure is baud) Circuit 1 from a
51 and a part acts on the lower part of the second 0 lock valve 185, and the spool F 8, which is pressed upward by the spring 179, is lowered by the hydraulic pressure acting from the boat through the circuit 152, thereby making it conductive. circuit 1
61 and 1621 are not cut off, and a portion is passed through the orifice 166 from the circuit 16 to the 2-8 shift box 1.
82 and from boat o passes through circuit 1.58 to the second governor 3 pH 4%. Then, when the l-2 shift box 181 is reached, the transmission is in the first forward speed state. When the vehicle starts in this state and reaches a certain speed, the governor pressure of the circuit 158 causes the l-2 shifter 160 of the l-2 shifter 181, which is pressed to the right by the spring 159, to move to the left and move forward. The automatic gear shifting operation from the first gear to the second gear is performed, and the circuit 15g and the circuit 161 are passed through four times, and the hydraulic pressure reaches the engagement side hydraulic chamber 169 of the servo 141 from the circuit 162 via the second lock valve 185, and the second brake 106 is engaged. , the transmission is in the second forward speed. In this case, l-
Since the 2-shift box 181 is compact, the spool 160 moves to the left at the required speed without increasing the speed at the shift point, and an automatic shift action from the first forward speed to the second speed is performed. Furthermore, when the speed reaches a certain speed, the governor pressure of the circuit 158 overcomes the spring 168 and the 2-8 shift fflδ
By pressing the spool 164 of 2 to the left, the circuit 167 and the circuit 168 are brought into conduction, and the hydraulic pressure is partially transmitted from the circuit 168 to the servo 1.
41 reaches the release side hydraulic chamber 170 and releases the second brake 106, and a portion reaches the front clutch 104 and engages it, and the transmission enters the 8th forward speed state.
When the speed selection rod is set to fluff forward 2nd speed same 2nd speed fixed, the spool 150 of the speed selection box 180 moves and the line pressure circuit 14
4 reaches the same place as po) b, o and d, rear
Clutch 105 is engaged while second lock valve 18 is engaged.
In the case of this H, there is no hydraulic pressure at the bottom of 5, and the area of the land above and below the part that opens to circuit 11F+ of spool 178 and where hydraulic pressure acts is larger at the bottom, so the spool of second lock ff185 178 is pushed down against the force of spring 179 to connect circuit 15g and circuit 162.
conducts, the hydraulic pressure reaches the engagement-side hydraulic chamber 169 of the servo 141, engages the second brake 106, and the transmission enters the second forward speed state. Hydraulic F1 circuit 154 from boat d
Through the solenoid down fist shift ff187 and throttle back up to reach 188 0 selection speed 1
80 port) t'itm between a and the line pressure circuit 144
Since the hydraulic pressure has not reached the 2-8 shift top lag from the circuit 151, the second brake 106 is not released and the front clutch 104 is engaged, and the transmission is in the 8th forward speed state. No problem.

The second lock fP185 works in conjunction with the speed selection 3P180 to fix the transmission in the second forward speed state. When the speed selection rod is set to the 1 (first forward speed fixed) position, the line pressure circuit 144 is set to 0. The oil pressure reaches the same place as in case 1 from boats o and d and engages the rear clutch 105, and from boat 8 it goes from circuit 155 to 1-2 shift box IJ11 to circuit 171.
A part of the low reverse e-brake 107 is reached, and the low reverse brake 1 acts as a forward reaction brake.
0? is engaged, the transmission is in the first forward speed state, and a portion reaches the left side of the l-2 shift) ff181 and acts together with the spring 159 to press the spool 160 to the right, so that the transmission is in the first forward speed state. is fixed.

Next, the creep prevention device 200 of the present invention will be looked at.

In the present invention, as described above, the line pressure supply path 15δ to the forward friction element (rear clutch) 105 is supplied with line pressure and engaged at all forward traveling positions (D, l, I) of the speed selection yP180. During this insertion, the line pressure supply path 158 is constructed into parallel pipes 202 and 208, and a pressure reduction timing cell g01 is inserted into this parallel pipe. is equipped with a sweat spool 201&, and the lower end surface of the spool is a pressure chamber! It faces O1b and has a spring 201O acting on its upper end surface, and when the square spool 2011 is at the right-hand position in the figure, the pipe SOW is passed through and the pipe 208 is
1! When ML is at the left hand position in the figure, the pipe line 802 is cut off and the pipe line 208 is opened.

The depressurization timing, g go 1 b, is connected to the line pressure supply path 15δ near the repository box 180 via a branch path 804, and a one-way orifice 2 is installed in this branch path jl104.
The one-way orifice 205 into which the 05 is inserted is connected to the communication hole 205&, the orifice 1051), and the communication hole 205&
Opening and closing the ball gogio and the pressure ggoi
When the line pressure is directed to b, the ball 2050 is connected to the communication hole 20.
5& is closed as shown in the figure, the line pressure is supplied at a slow speed determined by the orifice 206b, and the pressure chamber 101 is
When the line pressure is released from b, the ball 205o opens the communication hole 205&, and the line pressure can be quickly released through this communication hole.

An orifice 206 is provided in the middle of the line pressure supply path 158 that connects the ends of the parallel electric circuits 202 and 208 near the speed selection valve 180, and this line pressure supply path is connected to the branch path 20.
7 and an orifice 208 provided at its tip to communicate with a drain boat 209. The opening area of the orifice 208 is larger than that of the orifice 206, and the difference between these opening areas is determined so that the line pressure can be reduced in a predetermined manner to obtain the effect described below. An electromagnetic YGIO is installed opposite to the drain boat 209, and when the magnet is energized, the first runger 210a protrudes to the right half position in the figure to block the drain boat 209, and when it is deenergized, the grander 210 & Move back to the middle left position and drain boat 2
Figure 8 shows the control circuit of the electromagnetic piece 210, in which the idle switch 211, the vehicle speed switch 212, the OR time [213,
It is composed of a select switch 214, a timer 215, and a drive circuit 216.

The idle switch 211 is a switch that detects whether or not the engine is in an idle (no load) operating state.For example, it responds to depression of the accelerator pedal, and in a loaded state where the accelerator pedal is depressed, the idle signal SI, which is the output, is set to H. Zero vehicle speed switch g1 shall set the idle signal S1 to the L level in the released no-load state.
2 is composed of a vehicle speed sensor and a switching module, and outputs a vehicle speed signal Sv at H level when the value indicates the vehicle speed or the running state of the vehicle, and outputs a vehicle speed signal S■ when the value indicates the vehicle speed or the stopped state of the vehicle. It shall be set to L level.

The OR circuit 218 outputs the idle signal sI and the vehicle speed signal S1. When the engine is operating under load or the vehicle is running, an H level signal is supplied to the drive circuit 216, and the IIE magnet ygto is energized through this circuit. In the stopped state, an H level signal is not supplied to the drive circuit 216, and this circuit is not operated, thereby deenergizing the electromagnetic JP 21G. Select switch 2
14 is a selection signal S t which is output when the speed selection valve 180 (see Fig. 2) is in the forward traveling position of II and I.
-H level, and at other positions, this signal S, is set to L level.
The timer 215 outputs an H level signal for a predetermined period of time (described later) from the rise of the signal S, that is, from the instant the speed selection valve 18G is set to the forward travel position, and otherwise, regardless of the level of the signal S8. Assume that no H level signal is output.

Note that while the timer 21B outputs the H level signal, the drive circuit 216 receives this signal and energizes the solenoid valve 210.

The device of the present invention having such a configuration operates as follows.

When the speed selection valve iao is in a position other than the forward travel position,
As described above, line pressure is not supplied to the circuit 158, so the pressure reducing timing valve 201 is not guided to the pressure chamber 201b, and the valve spool 201! L is positioned at the right hand side in FIG. 2 due to the spring 201o, conducting the conduit 202 and transparently illuminating the conduit 208.

Here, when the speed selection valve 180 is set to the forward travel position during forward movement, line pressure is output to the circuit 158 as described above. This line pressure is supplied from the circuit 158 to the pressure chamber goib via the branch path 804 and the one-way orifice 205, but this pressure supply is supplied to the orifice 805b as described above.
2, the timing valve 801 moves the spool 201a up from the used hand position in FIG. 2 by the line pressure supplied to the chamber golb.
Since the speed is slow, the conduit gos is initially made conductive until t. Meanwhile, in response to the speed selection valve 180 being in the forward travel position, the timer ji15 supplies an H level signal to the drive circuit 816 for the set time from the moment the select signal S from the select switch 214 rises. Since the solenoid valve 210 is energized during the set time, the TA valve 21G closes the drain boat 209 with the plunger gtoa in the right-hand position in FIG. Therefore, circuit 1
Initially, when the speed selection valve 180 is placed in the forward travel position, the line pressure from 58 is directly supplied to the rear clutch (forward friction element) 105 via pipe B02.

Even when the vehicle starts by pressing the accelerator pedal immediately after operating the speed selection valve 180, there is no delay in engaging the rear clutch 105, and the vehicle starts smoothly without engine drying or large shocks. I can do it.

By the way, if you do not wish to start at this time and keep the vehicle stopped, the spool 201 & of the timing valve 201 will finally reach the pressure arm position in FIG. It is raised to cut off the conduit go2 and conduct the conduit wI208. At the same time, the timer 215 stops supplying the H level signal to the drive circuit 216 as the set time elapses, so that the %IIE solenoid valve ZIOH is deenergized and the deenergized 1 runger glO.
Retract a to the left half position in Figure 2 and connect the drain port 20.
9 opens 0 so this time the line pressure from 8158 to orifice 206, branch vsso' and orifice 20
8, part of the line pressure is removed and the pressure is reduced, and this reduced line pressure is spread between the orifices 206 and 208, and the pressure is determined by the difference in the opening area of the orifices 206 and 208. After 808, rear ri 2
105 and maintains it in the state immediately before tightening.
For this reason, the power transmission section shown in Figure 1 is rear
0 can cut off power transmission and prevent creep from occurring.
Note that in this stopped state, the vehicle speed switch 212 outputs the vehicle speed signal s1. as described above. Since the idle switch 211 does not set the idle signal s1 to the H level just in case the accelerator pedal is not depressed, the solenoid valve slo is not energized by these signals, and the above-mentioned creep prevention function is not activated. You can get it as long as you continue to stay stationary.

Then, when you desire a start and press the accelerator pedal, the idle switch 211 changes the idle signal sl to H level, and this signal passes through the OR circuit z18 to the drive circuit! As a result, the solenoid valve zl is supplied to 16.

is energized and drain shark-) Closes B 09. At this time, the line pressure from the circuit 15g is 80G
' will no longer be excluded from the 11th conduit so8
The power is supplied to the rear clutch 10B through the 0 to engage the rear clutch. Therefore, the rear clutch 105 becomes capable of transmitting power, and the vehicle can be started. By the way, at this time, the rear clutch 105 changes state from the state immediately before engagement to the engaged state with a slight stroke, so this change occurs quickly, and the engine speed due to the delay in engagement of the rear clutch 105 is reduced. It is possible to prevent the occurrence of nitrous blowing and the start shock that accompanies this dry blowing.

Furthermore, since the line pressure toward the rear clutch 105 passes through the orifice 206 at this time, the rear clutch 105 is not engaged too rapidly, and in this respect, the occurrence of start shock can also be prevented.

When the accelerator pedal is subsequently released in the forward running state, the idle switch 211 changes the idle signal S to the L level, but the vehicle speed switch 21g that detects the vehicle running state at this time indicates the vehicle speed No. 1 SX. This signal is sent to the drive circuit 216 via the OR circuit 218.
As a result, the IEla valve 210 continues to be energized even when the accelerator pedal is released (engine no-load operation) during forward travel, keeping the rear wheel clutch 105 engaged, and the vehicle traveling forward.

There will be no disruption to the line.

When the accelerator pedal is released from this running state to decelerate the vehicle and come to a stop, the tying valve 201 keeps the spool go1m at the left hand position in FIG. 2, but the idle switch 2111 and the vehicle speed switch 21B Output signal S
1. In order to set the S■ level to the L level, the solenoid valve 21G is deenergized and drained)! 09 opens 0 Therefore, the pressure is reduced to the rear clutch 105 in the same way as described above, and nine tons of pressure is introduced to the rear clutch 105, and this rear clutch is held in the state immediately before engagement, and power transmission is started here. Therefore, the occurrence of creep can be prevented in a stopped state with the speed selection valve 180 in the forward travel position.

Switch to the R and N positions and connect the circuit 158rt to the drain part of the speed selection valve 180, and at 9 o'clock, the pressure reduction timing valve 201(r)
The line pressure being supplied to the chamber 801b pushes the ball 205o of the one-way orifice 206 to open the communication hole 205.
& is opened, and the water is quickly removed from the branch passage 204, the circuit 158, and the drain section of the speed selection valve 180 through the communication hole 205&, rather than through the orifices g 05 and b. Because of this, the timing valve 201 momentarily closes the valve
a is returned from the left-hand position in FIG. 2 to the right-hand position in FIG. - can be quickly prepared for the next operation.

Thus, as described above, the creep prevention device of the present invention switches the speed selection valve 180 to the forward travel position (D, l, I) and when dead (
In the illustrated example, the line pressure is initially supplied as is to the forward movement friction element (in the illustrated example, the rear clutch 105) by the pressure reduction timing valve gol and the one-way orifice 205, and thereafter, as long as the engine is in a no-load state and the engine is stopped, Forward motion 1! Since the line pressure supplied to the element is reduced so that the forward friction element is maintained in the state immediately before engagement (in the illustrated example, by the orifice gos, gos and the solenoid valve 210), the speed selection valve 180t'1llll advance When switching to the running position and immediately starting by pressing the accelerator pedal, there is no time lag in the engagement of the forward friction element, and therefore, there is no engine revving or the accompanying start shock. Showa 561
The occurrence of creep can be prevented in the same way as the measures described in Japanese Patent No. 9848.

[Brief explanation of drawings]

1st v! A is a power train diagram of an automatic transmission to which the creep prevention device of the present invention is applied. FIG. 2 is a circuit diagram showing the creep prevention device of the present invention incorporated into the shift control hydraulic circuit of the automatic transmission. FIG. 8 is a block diagram showing the electronic control system of the device of the present invention. i 0 Rear clutch (fIJ advancement friction element)
. lδ0...Speed selection valve, 158...Line pressure supply path,
WOO... Creep prevention device of the present invention, 101...
Pressure reduction timing valve, 202.208...Parallel pipe line, 2
o4゜20 River branch, 2o5...One-way orifice. 206.208... Orifice, 2o9... Dorenbo), 21G... Solenoid valve, all... Idle switch, 212... Vehicle speed switch, 218... OR
circuit. 214...Select switch, 215...Timer. 216...Drive circuit. Patent applicant Nissan Motor Co., Ltd.

Claims (1)

[Claims] L Equipped with a forward friction element that is connected by being supplied with line pressure at all forward travel positions of the speed selection hole, and the combination of the engagement of the element and the engagement or release of other friction elements changes the forward gear position. In the selected automatic transmission, when the speed selection hole is switched from the neutral position to the forward travel position, the line pressure is initially supplied as is to the forward friction element f#, and then
A creep prevention device for an automatic transmission, characterized in that, when the engine is in a no-load state and the vehicle is stopped, the line pressure supplied to the forward friction element is reduced so as to maintain the line pressure in the state immediately before engagement. 0