JPS59180146A - Creep preventer for car fitted with automatic transmission - Google Patents

Abstract

PURPOSE:To improve the reliability of motion in a creep preventing valve, by constituting a device so as to use not only spring force but also hydraulic servo force for restoring force to a nonworking position of the creep preventing valve for escaping the engaging pressure of a starting frictional engagement element to an oil tank in time of idle running. CONSTITUTION:A spool valve body 85 belonging to a creep preventing valve Vc is connected to an accumulator 72 and simultaneously housed in a valve chest 86 which partitions an oil passage 84 short-circuited to an oil tank R into two parts 84a and 84b at both upstream and downstream sides, while a return spring 89 resiling the spool valve body 85 downward is housed in an upper oil passage 87. The spool valve body 85 is provided with a pair of top and bottom lands 90 and 91, an annular groove 92 being sandwiched between these lands and orifices 93 and 94 interconnecting this groove 92 to the upper oil passage 87 and a lower oil chamber 88. The annular groove 92 is always interconnected through to the upstream part 84a, while the upper land 90 opens or closes an opening port 84b with its up-and-down motion.

Description

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

For vehicles equipped with an automatic transmission, move the gear lever to drive position i.
If it is set in F# (forward position), the so-called creep phenomenon occurs in which the vehicle tries to move forward against the driver's will due to the drag torque of the Drukko/Park.

This creep force tries to apply a braking force to the engine during idling, so in order to maintain the engine speed at the reference value during idling, the throttle during idling must be adjusted to compensate for the braking force. It was necessary to keep the valve opening open, which led to increased fuel consumption, which was one of the main reasons for the poor fuel efficiency of automatic transmission I-4ton vehicles.

Therefore, the present applicant detects when the vehicle is idling and detours it to the oil tank at the engagement pressure of the starting clutch to connect the power transmission between the engine and the wheels, reducing the load on the engine to the same level as in a vehicle with a manual transmission. We first proposed an improvement plan that would improve the speed at the level of Then, while creep is being prevented, the pressure acting on the starting clutch is not completely reduced to zero, but is reduced to a weak pressure Pa that cannot counteract the spring force of the return spring in the clutch described in r3fJ. It is important to maintain this pressure, and this pressure (I)o is extremely weak, around 1 atm.Moreover, in order to maintain this pressure Po as accurately as possible, it is necessary not to let the above-mentioned holding pressure escape into the oil tank. A relief valve type device is suitable as the means, and its structure is such that the engagement pressure is used to open the valve body, and a spring force is used to quickly move the valve body to the closing side, and the valve body is engaged with the spring chamber via a throttle. A joint pressure is introduced, and a pilot valve is used to open and close the circuit for communicating the spring chamber with the oil tank. (=The spring force of the J-force spring must also be extremely weak)
There's no point. Therefore, if there are impurities such as dirt mixed into the oil, the valve body may not operate smoothly and the creep prevention mechanism may stop operating, making it difficult to re-engage the starting clutch. It lacked sex. This is because the valve body does not return to the rest position due to the weak spring force as mentioned above, or the return of the valve body is delayed. However, doing so would require increasing the size of the creep prevention valve.

The present invention has been made in view of the above-mentioned problems, and the present invention has been made in view of the above-mentioned problems. To provide a creep prevention device for a vehicle with an automatic transmission that improves the reliability of the operation of a creep prevention valve by using not only a spring force but also a hydraulic servo force for the return force to the position.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. First, in FIG. 1, which shows an outline of an automatic transmission for an automobile with three forward speeds and one reverse speed, the output of the engine E is transferred from its crank lll11 to a torque converter T1. Auxiliary transmission M
, are transmitted to the driving wheels W, W sequentially through the differential device Df,
Drive these.

The torque converter 'r consists of a pump impeller 2 connected to a crankshaft 1, a turbine impeller 3 connected to an input 41+5 of an auxiliary transmission M, and a stator shaft rotatably supported by an input shaft 5''. The stator wheel 4 is connected to the stator wheel 4 via a one-way clutch 7. The torque transmitted from the crankshaft 1 to the pump wheel 2 is hydrodynamically transmitted to the turbine wheel 3, and during this time, the torque is amplified. Bear the reaction force by 1.

At the right end of the pump blade jN, 2 is the hydraulic pump shown in Figure 2.
] A pump drive shaft 8 is provided to drive the pump, and a stake arm 4b which controls the regulator valve Vr shown in FIG. 2 is fixed to the right end of the stake shaft 4a.

Between the output shafts 5 and 6 of the auxiliary transmission M, which are parallel to each other, are a low speed gear train Gl, a middle speed gear train G2, and a high speed gear train G.
2, and a reverse gear train Gr are provided in parallel. The low-speed gear train G1 is connected to the input shaft 5 via the low-speed clutch C1 as a friction engagement element for starting, and 4) the drive gear 17;
Fixedly installed on the output shaft 6! The intermediate speed gear train G2 is composed of a driven gear 18 that meshes with the input shaft 5, and a driving gear 19 that is connected to the input shaft 5 via the intermediate speed clutch C2, and a switching clutch Cs that is connected to the output shaft 6. The first high-speed gear train G2 includes a driven gear 20 that is connected to the gear 19 via a driven gear 20 and meshes with the gear 19. and a driven gear 22 connected to each other.
r is a drive gear 23 formed integrally with the first drive gear 19 of the middle speed gear train G2, and the switching clutch Cs on the output shaft 6.
A driven gear 24 and both gears 23 .
24 and an idle gear 25 meshing with I'-. The front gear 9J1 center clutch Cs is the driven gear 20.2.
4, and selectively connects the driven i20.24 to the output shaft 6 by shifting the selector sleeve 26 of the clutch Cs to the forward position on the left or the reverse position on the right in the figure. I can do it.

Therefore, when the selector sleeve 26 is held in the forward position as shown in the figure, if only the low gear clutch C1 is connected, the drive tooth "17" is connected to the input 11qi+5 and the low gear train G, is established, and this gear train G1
Torque is transmitted to the output shaft ゛6 from the input @15 through
Slurped. Next, when the middle speed clutch C2 is connected in the march with the low speed clutch C3 in the disengaged state, the 7 drive gear 19 is connected to the input shaft 5 and the middle speed gear train G2 is established. Torque is transmitted from the input shaft 5 to the output shaft 6 via the row G2. Furthermore, by blocking the low speed clutch C1 and the middle speed clutch c2 and connecting the high speed clutch C3, the driven gear 22 is connected to the output shaft 6 and a high speed gear train G3 is established. Torque is transmitted from the input shaft 5 to the output shaft 16 via G3. next,
By switching the selector sleeve 26 to the right reverse position and connecting only the middle speed clutch C2, the driving gear 23 is connected to the input shaft 5, the driven gear 24 is connected to the output shaft 6, and the reverse gear train Gr is established. However, torque is also transmitted from the input shaft 5 to the output shaft 6 via the minus gear train (rr).

The torque transmitted to the output shaft 6 is transmitted from the output gear 27 provided at the end of the shaft 6 to the large diameter gear 28 of the differential device Df.

In FIG. 2, a hydraulic pump P sucks up oil from an oil tank R and pumps it into a hydraulic oil passage 29. After this pressure oil is regulated to a predetermined pressure by a regulator valve Vr, it is sent to a manual valve Vm. ko(D?'l11 pressure is called line pressure P1.

The regulator valve Vr has a pressure regulating spring 3o and a spring receiver 31 that supports the outer end of the spring receiver 3o, and the spring receiver 31 can be moved left and right to adjust the set load of the pressure regulating spring 30. can. The stator arm 4b is in contact with the outer surface of the spring receiver 31 so as to apply a reaction force acting on the stator wheel 4, that is, a stator reaction force. A stator spring 32 supporting the stator 1 is attached. Therefore, as the stator reaction force increases, the λ scale data (4h3'l) is compressed, so
As a result, the line pressure IN of the hydraulic oil passage 29 increases by 1]-. .

A part of the pressure oil whose pressure is regulated by the regulator valve Vr passes through the inlet oil passage 34 with the throttle 33 and then to the torque converter]
Let's be guided inside and stop the cavitation at 19 points 5
The inside is pressurized 1-, but this internal pressure is
It is determined by the thickness of the torque converter T, the strength of the spring 37 of the check valve 36 provided in the oil passage 35, etc.

The oil that has passed through the check valve 36 returns to the oil tank R via the oil cooler 56.

The surplus of pressure oil discharged from the hydraulic pump P is guided to the lubricating oil path 38 by the regulator valve Vr and sent to each lubricating part, but in order to ensure the minimum necessary oil pressure at this time, the pressure regulating valve 39 is used. be connected to the lubricating oil path 3B.

The pressure oil sent to the manual valve Vm is connected to the clutches (-1+C2, C3) when the valve Vm is in the neutral position shown in the figure.
It is not sent to any of the other hydraulic actuation parts. Therefore, all three clutches C1+C2I C3 are placed in a disengaged state, and the torque of the engine E is applied to the wheels W.
, W is not transmitted.

When the manual valve V m is moved from the position shown in the figure to the leftmost position and shifted to the drive position, the oil pump P
A hydraulic oil passage 29 from the oil passages 43 and 118 communicate with each other,
A hydraulic oil passage 41 in which the oil passage 111 communicates with the hydraulic cylinder 40a of the low-speed clutch CI and is provided with a one-way throttle γ5.
Connects to a. The sweet oil passage 112 is cut off from the hydraulic oil passage 41b leading to the oil pressure/cylinder 40b of the middle speed clutch C2, and the oil passage 113a is also disconnected from the hydraulic oil passage 41b. It is connected from exit port 1-114. Oil passage 115 continues to communicate with discharge bow 1-116. The hydraulic oil passage 43 communicates with the spring chamber 42 of the hydraulic servo motor Sm for shifting the selector sleeve 26, and thus the piston 4 of the servo motor Sm.
4 remains in the leftward movement position shown in the figure, and holds the selector sleeve 26 in the forward position 1d in the state shown in FIG. 1 via the shift fork 45. Therefore, the reverse gear train Gr is placed in a small operating state.

A manual oil passage 46 that connects to the input port of the governor valve Vg branches from the hydraulic oil passage 29, and a first signal oil passage 47 advances from the output port of the valve Vg.

The governor valve Vg is a known one, and is rotated around its own rotation shaft 49 by a gear 48 that meshes with a large-diameter gear 28 of a differential device Df. Therefore, its rotational speed is proportional to the vehicle speed.
- Therefore, the governor valve Vg outputs oil pressure proportional to the vehicle speed, that is, governor pressure pg, to the first signal oil path 4γ due to the action of the centrifugal force acting on the spool valve body 500 and the weight 51.
-I can do something.

Further, an oil passage 53 branches off from the hydraulic oil passage 43, and this oil passage 53 is connected to the first throttle valve Vt via a modulator valve 54. The modulator valve 54 is a pressure reducing valve that is biased toward the closing side by a spring force and configured to be closed by the modulator pressure of the output port 54a, and defines two limit values of the inlet pressure of the first throttle valve Vt1.

The first throttle valve Vt is of a known type, and includes a stool valve body 55, a control spring 58 that presses the valve body 55 to the left, a stiffening spring 57 that presses the valve body 55 to the right, and a control spring 58. A control screw 1-759 that supports the outer end, a control cam 60 that rotates in conjunction with an increase in the opening of the throttle valve of the engine E and moves the control piston 59 to the left, and an adjustment bolt that can adjust the center load of the return spring 57. 61 etc. control piston 5
9 moves to the left (1-), the displacement is transmitted to the spool valve body 55 via the control gene 58 and pushes it to the left. Since the output oil pressure acts on the left/if portion 55a of the spool valve body 55 to push the spool valve body 55 back to the right, the first throttle valve Vt is a hydraulic pressure proportional to the throttle valve opening of the engine E. That is, the throttle pressure pt is outputted to the second signal oil passage 52. Note that the counterclockwise rotation of the control cam 600 continuously restricts the communication between the oil passage 117 and the oil tank R.

The first and second signal oil passages 47.52 are respectively connected to pilot hydraulic chambers 62a, 62b, 63a, 63b at both ends of the low-medium speed shift valve (1) and the medium-high speed shift valve (2). As a result, these shift valves V,
, V2 receive front d-pig governor pressure Pg and throttle pressure pt on both end faces, and are operated as follows.

That is, the spool valve body 64 of the low-medium speed shift valve V1 initially remains in the rightward movement position shown in the figure by the force of the spring 66, and therefore the oil passage 118 is connected to the hydraulic oil passage 41a via the oil passage 111.
, and the low speed clutch C1 is pressurized and engaged. Next, the vehicle speed increases and the governor pressure Pg increases, and the left power of the spool valve body 64 due to this governor pressure Pg increases to the throttle pressure p.
When overcoming the right force of the valve body 64 by t and the spring 66,
Click/move mechanism 6 provided at the right end of the valve body 64
Click ball 68 moving together with valve body 64 at 7
passes over the fixed positioning protrusion 69, and the valve body 64 is rapidly switched to the left-hand position. As a result, the oil passage 111 communicates with the drain oil passage 119, and the oil passage 118 communicates with the oil passage 70. The oil passage 70G is cut off from the drain oil passage 120. In this state, if the high-speed shift valve v2 is in the illustrated position, the oil passage 70 communicates with the oil passage 113 provided with the one-way throttle 121, and further communicates with the hydraulic oil passage 41b via the manual valve Vm.

Therefore, hydraulic oil is supplied to the oil/J Nino cylinder 4'Ob, and the middle speed clutch c2 is engaged under pressure. As a result, the middle speed gear train G2 is established.

As the speed increases, a similar effect occurs in the medium-high speed shift valve V2, and the spool valve body 65 of the core valve V2 moves to the left due to the increased governor pressure Pg, and the oil passage 113 to the drain oil passage 122, and the oil passage 70 to the hydraulic pressure cylinder 40c of the high-speed clutch C3 and a) hydraulic oil passage 41c, and the hydraulic oil passage 41c to the drain oil passage 1.
Isolated from 23 people. Therefore, the middle speed clutch C2 is released from its engaged state, and the high speed clutch C3 is pressurized and engaged, and the high speed two-way train G3 is established.

To soften the shock during gear shifting, each clutch C4+
C2 and C3 are hydraulically connected in parallel with accumulators 72,
73 and 74 are connected. Also, in the drain oil path 119]
-2 oriice control valve 124 is provided, and the drain oil path 1
22 is provided with an orifice control valve 125.

Back pressure chamber of each accumulator 72, 73, 74? 7.78
．． 79 indicates the second throttle valve vt2 and the control oil pressure Pc.
is guided through the oil passage 106. , the second throttle valve vt2 is inserted between the oil passage 105 branched from the oil passage 53 and the oil passage 106, and the second throttle valve vt2 is inserted between the oil passage 106 and the spool valve body 107.
and a control spring 108 that presses the valve body 107 to the left.
It has a control piston 109 that supports the outer end of the control spring 108, and a control cam 110 that rotates in conjunction with an increase in the throttle opening of the engine E and moves the control piston 109 to the left. When the control piston 109 moves to the left, the displacement is transmitted to the spool valve body 107 via the control spring 10B, and the spool valve body 107 moves to the left. This left movement ((accompanyingly, the hydraulic pressure output to the oil passage 106 is
Push it to the right 1" to act on the left shoulder 107a of the spool valve body 107. By such an operation, the second throttle valve t2 controls the hydraulic pressure proportional to the throttle opening of the engine E to the back honeycomb chambers 77 to 79 of each of the accumulators 72 to 74 via the oil passage 106. Give a gift 1 [ro. Note that the counterclockwise rotation of the control cam 1100 continuously restricts the communication between the drain oil passage 120 and the oil tank R).

During deceleration, the valve body 65 of the medium-high speed shift valve V2 first changes from the speed ratio of the high speed gear to the speed ratio of the medium speed gear, and when the speed further decreases, the valve body 65 of the medium-high speed shift valve V changes from right-hand drive 1 to the speed ratio of the high speed gear. The F body 64 moves to the right and becomes the speed ratio of the low speed gear. The key point is that the hydraulic oil supplied to the low speed clutch C1 passes through the one-way throttle 75 when the speed ratio of the low speed gear is at such a drive position.

An intermediate portion of the hydraulic oil passage 41a is connected to the accumulator 72, and an oil passage 84 short-circuited to the oil tank R is connected to an intermediate portion of the hydraulic oil passage 41a. A pilot type creep prevention valve Vc is inserted in the middle of this oil passage 84.

The creep prevention valve Vc has a spool valve body 85, and this spool valve body 85 connects the oil passage 84 with an upstream portion 84a,
It is accommodated in a cylindrical valve chamber 86 formed in the middle part of the downstream part 84b, thereby defining oil chambers 87 and 88 at the bottom of the two parts of the valve body 85. be done. A return spring 89 that urges the spool valve body 85 downward is accommodated in the two-part oil chamber 87. The sandwiched annular groove 92 and this groove 92 are connected to the upper oil chamber 87.
:t6 and an orifice 93°94 communicating with the lower oil chamber 88. The annular groove 92 is always in communication with the downstream part 84a, and the upper land 90 is in communication with the downstream part 84b due to its vertical movement.
Opening/closing the opening boat 95 to the valve chamber 86 - 4" 6° This boat 95 is preferably circular in shape,
According to the upward movement of the first land 90, its effective amount “1 side A11
is created so that it gradually increases.

An end wall hole 9 having an orifice 96 is provided at the upper end of the valve chamber 86.
7 is provided, and an electromagnetic tP99 having a pilot needle valve 98 for opening and closing an orifice 96 is further distributed thereon. This side valve 98 closes the orifice 96 by the spring force of the spring 100, and opens the orifice 96 when the solenoid 101 is energized. When the diverted orifice 96 is opened, it branches from the downstream portion 84b of the oil passage 84 and communicates with a bypass oil passage 102.

When the oil pressure l-' 101 is excited and the orifice 96 is opened, the upper oil chamber 87 is opened to the orifice 96.
and the oil tank (ζ) via the bypass oil passage 102, the oil pressure in the upper oil chamber 8 is reduced, and the spool valve body 85 is moved upward by the force acting on the lower end face facing the lower oil chamber 88. Then, the oil passage 84 is opened.At this time, the pressure in the hydraulic oil passage 41a1, in other words, the low gear flange C, is determined by the return spring 89 and the effective cross-sectional area of the spool valve body 85, so the pressure is applied to the low gear clutch. By setting the engagement pressure below the CI, it is possible to prevent the creep phenomenon from occurring.In addition, the valve body 64 of the low-medium speed shift valve V and the medium-speed shift valve V can be prevented from occurring.
When the valve body 65 of the high-speed shift valve V2 moves to the left and the speed ratio of the middle speed gear or the high speed gear is established, the oil pressure in the hydraulic oil passage 41a is low, so the spool valve body 85 moves. This does not occur, and the cleave (I) stop valve Vc does not operate.

What should be noted here is the upper oil chamber 8 of the throttle valve body 85.
The part facing the pressure receiving pressure 1 river 85a is the [: part oil chamber 88
The pressure-receiving area is larger than that of the second pressure-receiving ridge 1185b at the portion facing the second pressure-receiving ridge 1185b. That day/1-Ukej old r1
Create a difference in the product 1-eyebrow i-bO~3 is open-ropo-1-9
5, and does not affect any vertical movement of the valve body 85. Pilot needle valve 98 closes tf
In this state, the pressure in Juto's oil chambers 87 and 8B is amazing! , 1-li, the valve 1 tree 85 is closed by the spring force of the return spring 89 and the received pressure jrl: 85 a, 851)'s j, n + product difference multiplied by the oil pressure (i)! Rent a place to move.

'ii, the solenoid 101 of the magnetic valve 99 is grounded via an L transistor 140;
00 base has a resistor 146 and an AND gate 141
The output of is given. The input terminal of the AND gate 1410 outputs the IHA issue of NO IREPEL when the shift lever is shifted to the drive position I).
The engine speed sensor 142 detects the rotational speed of the engine E and outputs a level signal when it is below a reference value.The engine speed sensor 143 outputs a level signal when the brake pedal is depressed. 1-brake sensor 144 is connected. Therefore, when the vehicle is stopped by placing the foot on the flake pedal at an intersection, the outputs of the sensors 142 to 144 are all at a high level, the solenoid 101 is energized, the creep prevention valve Vc is opened, and the creep prevention valve Vc is opened. Prevent the phenomenon from occurring.

In this way, for the first step in preventing leap, the throttle 75 provided in the middle of the oil passage 41α plays an important role. Here, the diameter of the throttle 75 is d1. If the diameter of is Di, the discharge pressure of the hydraulic pump P is PI, and the hydraulic pressure of the hydraulic oil passage 41a is p and 1-, then
The following formula holds true.

Here p+=s, sy=, p=], OM, d=]
, 7 mm, then Di=2.8+n+n.

In reality, other interference factors also come in (a), so Dl is set to 5 to 6 φ, but (i) 1 does not have such a large value. Further, the creep prevention valve Vc is arranged as close as possible to the low speed clutch C1 in order to improve responsiveness at the time of starting.

When the manual valve Vm is shifted to a shift I position other than the drive position, in other words, to the 1st gear holding position, only the low gear clutch C1 is pressurized and engaged, and the middle gear operating position ■
Alternatively, when shifting to the reverse position Re, only the middle gear clutch C2 is pressurized and engaged to establish the middle gear train G2- or the reverse gear train Gr.

! 1. When shifted to the reverse position Tle at f, the piston 44 of the servo motor Sm receives pressure oil on its left end surface, and the splash chamber 4 is connected to the oil tank R, so the piston 44 moves to the right and the above-mentioned As shown, the reverse gear train Gr is
☆I-ru. In addition, manual valve Vm shift f)゛Silk 1'
■) 1 in 1'' indicates a barging force of 1.

Next, to explain the operation of this embodiment, assume that the vehicle is stopped by placing the foot on the brake pedal at an intersection, for example. In this case, each sensor 142-1
Since the signal from 44 is at high level -, the output of AND gate 141 is at high level, so transistor 140 is conductive and solenoid 101 is energized.

In response, the pilot needle valve 98 lifts, the pressure oil in the two-part oil chamber 87 is released to the oil tank R, and the valve body 85 is moved upward by the hydraulic pressure from the hydraulic oil passage 41a acting on the lower oil chamber 88. , the oil passage 84 is communicated with the oil tank R, thereby preventing the occurrence of creep phenomenon. At this time, even if the movement of the valve body 85 is obstructed by dirt or the like in the oil, it will be introduced into the lower oil chamber 88. (a) Since the working oil pressure is constant, the valve body 85 will be in the open position. be forcibly moved up.

In order to start the vehicle from such a stopped state, il+-
,,7' When you release your foot from the rake pedal and press the pedal, the sensors 134 and 144 output a low level of 100, so the renoid 101 becomes /i''i.
(As a result, the oil pressures in the upper oil chamber 87 and the lower oil chamber 88 become equal, but the j-th receiver of the valve body 85
Since the area of a is larger than the area of the second pressure receiver 85b, the valve body 85 is moved downward to the closed position by the force of the return spring 89 and the downward pressing force due to the difference in area. Ru. Therefore, it is possible to prevent the valve body 85 from becoming stuck in the open can i^' due to the influence of dust and the like.

As described above, according to the present invention, the creep prevention valve (+17I) is configured so that it operates in two directions, opening and closing with the pressure of soil and hydraulic pressure, so that the return force of the creep prevention valve to the non-operating position is dependent on the hydraulic pressure. A servo can be used to prevent the valve body from not returning to the 11th position of the body due to the weak spring force, or from causing stiffness due to a slow return operation. As a result, the reliability of operation can be improved without increasing the size of the creep prevention valve and increasing the spring force.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a schematic diagram of an automatic transmission with three forward speeds and one reverse speed to which the present invention is applied, and FIG. 2 is a hydraulic circuit diagram thereof. C1...Low speed clutch as a friction retention element for starting,
M・-Auxiliary transmission, T torque controller, P・hydraulic pump, R・oil tank, Vc creep prevention valve, 41
a- Hydraulic oil passage, 84...Oil passage, 85 Susol valve body, 8
5 a, 85 b Pa pressure receiving surface 0 Patent applicant Book 1
” 1 technique (Ijf Kogyo Co., Ltd. 1)゛ Ben JE =
Kei Ochiai F.

Claims (2)

[Claims] (1) The oil passage leading to the oil tank branches from the hydraulic oil passage that supplies hydraulic pressure to the starting IM friction engagement element of the auxiliary transmission connected to the hydraulic torque converter, and the nuclear oil passage is connected to the vehicle. A) In a creep prevention device for a vehicle with an automatic transmission equipped with a creep prevention valve that opens during idling operation, the creep prevention valve operates in two directions: open and close by the pressure of a hydraulic source. 1. A creep prevention device for an automatic transmission gear vehicle, characterized in that: (2) The creep prevention valve has a first pressure receiver having a large area for receiving the hydraulic pressure from the hydraulic source on the valve closing side, and a second pressure receiving valve having a narrow area for receiving the hydraulic pressure on the valve opening side. During normal operation, the oil pressure is applied to both pressure receiving surfaces, and before idling operation, only the hydraulic pressure applied to the first receiver r== +(+i) is released. The scope of Patent No. 511, which is characterized by the following, paragraph (]);