JPH0477829B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic transmission with a fluid coupling for a vehicle that is equipped with a creep prevention means, and in particular to an automatic transmission for a vehicle that is equipped with a creep prevention means that allows the vehicle to start smoothly when the hydraulic oil is at a high temperature. Regarding transmission.

In a vehicle equipped with an automatic transmission, when the vehicle is stopped with the gear shift lever set in the forward position, the driver's will is affected due to the drag torque of fluid couplings such as torque converters used in the automatic transmission. On the other hand, a so-called creep phenomenon in which the vehicle tries to move forward is observed. This creep force applies a torque load to the engine during idle operation, so
This is unfavorable from the standpoint of fuel economy, and in such cases, the transmission is automatically placed in a neutral state, power transmission between the engine and tires is cut off, and the opening of the engine throttle valve is reduced accordingly to ensure economy. It is preferable. It is also known that anti-creep devices used for this purpose also reduce vibrations during engine idling;
The effect is remarkable in FF cars.

Creep can be prevented by reducing the transmission torque capacity of the frictional engagement element for starting, that is, the first gear clutch, to substantially zero, but when the next time the vehicle starts moving, this Capacity must be restored. Particularly during sudden starts, this recovery speed must be as fast as possible, otherwise the first gear clutch will engage after the engine speed has increased, resulting in an unpleasant shock and premature clutch wear. . In this way, in order to increase the internal pressure of the first gear clutch in response to the throttle depression, the pressure in the first gear clutch is not reduced to zero even during creep prevention, but the pressure in the first gear clutch is increased. It is known that it is desirable to set the pressure as close as possible to and below the pressure that causes the clutch to engage against the spring (this is called the engagement pressure P _e ). This is because the first speed clutch is made up of various elastic bodies, including its oil passage, and the pressure oil deforms these elastic bodies one after another, increasing the clutch's operating pressure to the engagement pressure P _e . ,
Such an elastic body slows down the rise of hydraulic pressure,
This is because it is thought that responsiveness will be deteriorated. Examples of such elastic bodies include the invalid stroke of a piston and air mixed in hydraulic oil.

However, considering the manufacturing tolerances of the return spring of the first gear clutch and the machining tolerances of the parts that house it, it is inevitable that this engagement pressure P _e will vary considerably, and therefore the first speed clutch during creep prevention It is difficult to precisely set the speed clutch pressure as described above, and if this was attempted to be achieved by improving dimensional accuracy, there was a problem in that the cost would increase.

In view of these shortcomings of the prior art, the main object of the present invention is to provide a vehicular transmission equipped with a creep prevention means that can adjust the working oil pressure of the first gear clutch during creep prevention. There is a particular thing.

According to the present invention, such an object includes a fluid coupling, a power transmission means including a gear train or the like for transmitting the output torque of the fluid coupling, and a power transmission means for controlling the power transmission capacity of the power transmission means. In an automatic transmission for a vehicle comprising a hydraulically operated frictional engagement means and a creep prevention means for variably controlling the power transmission capacity of the frictional engagement means, the creep prevention means comprises:
The anti-creep valve is connected in series to a conduit that supplies hydraulic pressure to the frictional engagement means, and the anti-creep valve is connected between an input oil passage, an output oil passage, and between the output oil passage and the throttle pressure. a valve body that opens and closes communication between the input oil passage and the output oil passage in response to differential pressure and spring biasing force; and a throttle passage that constantly communicates the input oil passage and the output oil passage. , a feedback oil passage capable of communicating the discharge oil passage and the output oil passage by movement of the valve body that starts to close communication between the input oil passage and the output oil passage, and the creep prevention means Screw means is provided for adjusting the spring force of the spring in order to adjust the hydraulic pressure held in the frictional engagement means when the power transmission capacity of the frictional engagement means is reduced to a level that prevents creep. This is achieved by providing an automatic transmission for a vehicle that is characterized by:

By making it possible to adjust the hydraulic pressure held by the first gear clutch during creep prevention, it is possible to accommodate errors in the set value of the engagement pressure P _e due to slight dimensional errors. This makes it possible to easily manufacture a vehicular automatic transmission equipped with such a creep prevention means and to reduce its manufacturing cost.

The invention will now be described in detail with reference to specific embodiments and with reference to the accompanying drawings.

FIG. 1 shows four forward speeds and one reverse speed to which the present invention is applied.
This figure shows an overview of automatic transmissions for automobiles. The output of the engine 1 is transmitted from the crankshaft 2 to the drive wheels 6, 6' via a hydraulic torque converter 3, a gear transmission 4, and a differential gear 5.
Drive these.

The torque converter 3 includes a pump impeller 2 connected to a crankshaft 1, a turbine impeller 3 connected to an input shaft 8 of a gear transmission 4, and a stator shaft 10 relatively rotatably supported on the input shaft 8. The stator wheel 12 is connected to the stator wheel 12 via a one-way clutch 11. From the crankshaft 2 to the pump impeller 7
The torque transmitted to the turbine wheel 9 is hydrodynamically transmitted to the turbine wheel 9, and during this time, the torque is amplified. In a known manner, the stator wheel 12 bears the reaction forces occurring in this case.

The pump impeller 7 further includes a hydraulic pump 36 shown in FIG.
A pump drive gear 13 for driving the pump is provided, and a stator arm 1 for controlling the regulator valve 38 shown in FIG. 2 is provided at the right end of the stator shaft 10.
0a is fixed.

Input and output shafts 8 of the gear transmission 4 that are parallel to each other,
Between 18 and 18, there is a first speed gear train G ₁ on the lowest speed side, a second speed gear train G ₂ , a third speed gear train G ₃ on the highest speed side, a fourth speed gear train G ₄ on the highest speed side, and a reverse gear train G _r are installed in parallel.

The first gear train G ₁ includes a drive gear 15 connectable to the input shaft 8 via a first gear clutch 14 and a one-way clutch 1 meshed with the gear 15 and connected to the output shaft 18 .
7, and a driven gear 16 that can be connected via a driven gear 16.

The second speed gear train _G2 consists of a drive gear 21 that can be connected to the input shaft 8 via a second speed clutch 22, and a driven gear 23 that is fixed to the output shaft 18 and meshes with the drive gear 21. ing.

The third gear gear G ₃ includes a drive gear 24 fixed to the input shaft 8 , a driven gear 25 meshing with the drive gear 24 and connectable to the output shaft 18 via the third gear clutch 26 . It is made up of

The fourth speed gear train G ₄ includes a driving gear 27 connectable to the input shaft 8 via a fourth speed clutch 28, a driven gear 29 meshing with the driving gear 27, and an output shaft 1.
8, and a reverse selector 30 that selectively connects the driven gear 29 and the reverse hub 31.

Further, the reverse gear train G _r includes a drive gear 32 that is integrally provided with the drive gear 27 of the fourth speed gear train G ₄ .
an idle gear 33 meshing with the drive gear 32;
The driven gear 34 meshes with the idle gear 33 and is connectable to the reverse hub 31 via the reverse selector 30.

The reverse selector 30 is connected to the driven gear 2
By shifting the reverse selector 30 to the forward position on the left side or the reverse position on the right side in FIG.
4 can be selectively connected to the output shaft 18 via the reverse hub 31. Further, the one-way clutch 17 transmits only the drive torque transmitted from the engine 1 toward the output shaft 18, and does not transmit torque in the opposite direction.

Therefore, when the reverse selector 30 is held in the forward position as shown, if only the first gear clutch 14 is connected, the drive gear 15 is connected to the input shaft 8 and the first gear train G ₁ is connected. is established, and torque is transmitted from the input shaft 8 to the output shaft 18 via this gear train _G1 . Next, if the second speed clutch 22 is connected while the first speed clutch 14 is connected, the drive gear 21 is connected to the input shaft ₈ , establishing the second speed gear train _G2 , and the input shaft 8
Torque is transmitted from the output shaft 18 to the output shaft 18. On this occasion,
The first gear clutch 14 also remains engaged, but
Due to the action of the one-way clutch 17, the first speed gear train
G ₁ is connected to the second gear train G ₂ without transmitting torque.
is established.

In the 3rd and 4th speeds, do the same as above,
The first gear clutch 14 remains engaged, but
Due to the action of the one-way clutch 17, the first speed gear train
G ₁ does not transmit torque. That is, when the second speed clutch 22 is released and the third speed clutch 26 is connected, the driven gear 25 is connected to the output shaft 18 and the third speed clutch 26 is connected.
A speed gear train G ₃ is established. If the third speed clutch 26 is released and the fourth speed clutch 28 is connected, the drive gear 27 is connected to the input shaft 8 and the fourth speed gear train _G4 is established.

Furthermore, if the reverse selector 30 is moved to the right in FIG. 1 and only the fourth speed clutch 28 is connected, the driving gear 32 is connected to the input shaft 8, the driven gear 34 is connected to the output shaft 18, and the reverse movement is started. Gear train G _r
is established, and reverse torque is transmitted from the input shaft 8 to the output shaft 18 via this gear train G _r .

The torque transmitted to the output shaft 18 is transmitted to the large diameter gear 20 of the differential device 5 from an output gear 19 provided at the end of the output shaft.

FIG. 2 shows a simplified hydraulic circuit of a vehicle automatic transmission equipped with creep prevention means according to the present invention. The hydraulic pump 36 sucks up hydraulic oil from the oil tank 35 and pumps it into the hydraulic oil passage 37. A part of this pressure oil is supplied to the torque converter 3 via the regulator valve 38, and since the regulator valve 38 is controlled by the stator arm 10a, the inside of the torque converter 3 is adjusted according to the load of the torque converter 3 to prevent cavitation. will be pressurized. Moreover, this pressure oil is supplied to the regulator 38.
The pressure is regulated to a predetermined level by the action of the hydraulic oil passage 37.
is supplied as line hydraulic Pl. Line Hydraulic Pl
is supplied to the throttle valve 41, manual valve 39, and governor valve 42.

The throttle valve 41 is of a known type and outputs a throttle pressure proportional to the throttle opening to the output oil passage 46. The governor valve 42 is also of a known type and outputs a hydraulic pressure corresponding to the rotational speed of the large-diameter gear 20 of the differential device 5, that is, a governor pressure proportional to the vehicle speed, to the output oil path 47. These throttle pressure and governor pressure are the 1st-2nd speed shift valve 43, the 2nd-3rd speed shift valve 48, and the 3rd-speed shift valve 48, respectively.
Each end of the four-speed shift valve 50 is provided to control the movement of the valve discs of these shift valves.

The line hydraulic pressure supplied from the hydraulic oil passage 37 to the hydraulic oil passage 40 via the manual valve 39 is applied to the first gear clutch 14 and the second gear clutch 22 according to the throttle pressure and governor pressure based on a predetermined shift pattern. , the third speed clutch 26, the fourth speed clutch 28, or the actuator of the reverse selector 30. Generally, when the vehicle starts, the line oil pressure of the oil passage 40 is reduced to the oil passages 45 and 1.
It is output only to the first speed clutch 14 via 4a,
Only the first speed gear train _G1 is established.

When the vehicle reaches a certain speed, the line oil pressure is applied not only to the first gear clutch 14, but also to the first gear through the first-second gear shift valve 43, the second-third gear shift valve 48, and the oil passage 22a. It is also supplied to the second speed clutch 22, and the second speed gear train _G2 is established. When the vehicle speed further increases, the 2nd-3rd speed shift valve 48 is also shifted, and the oil pressure of the 2nd speed clutch 22 is transferred to the drain oil path 4.
9 and line oil pressure Pl is supplied to the third gear clutch 26 via the third-fourth gear shift valve 50 and the oil passage 26a, and the third gear train _G3 is established. When the vehicle speed further increases, the 3rd-4th gear shift valve 50 also shifts, and the oil pressure of the 3rd gear clutch 26 is discharged from the discharge oil passage 51, and the line oil pressure Pl is supplied to the 4th gear clutch 28 from the oil passage 28a. , the fourth gear train G ₄ is established. The hydraulic circuit of such a vehicle automatic transmission is well known, and detailed explanation thereof will be omitted.

A creep prevention valve 52 is connected between the oil passage 45 and the oil passage 14a. This creep prevention valve 5
The pressure receiving area of the second valve body 53 at its upper end is larger than the pressure receiving area at its lower end. Further, the middle part of the valve body 53 is made smaller in diameter, and an annular cavity 62 is defined on its outer periphery, and the cavity is defined at the lower side of the valve body 53 through a small hole 55. It communicates with room 61. A spring chamber 60 is defined at the upper end of the valve body 53, and a spring 58 received in the spring chamber 60 constantly urges the valve body 53 downward. The upper end of the spring 58 is in contact with an adjusting screw 65, and by screwing the adjusting screw 65 up and down, the spring force of the spring 58 can be adjusted. 65a is a lock nut for fixing the spring 58 in any adjustment position, and 65b is a removable dust boot for protecting the adjustment screw 65.

A bypass oil passage 69 branches from the input oil passage 45 of the creep prevention valve 52, and is connected to the filter 64 and the throttle valve 5.
4 to the output oil passage 14a of the creep prevention valve 52.
are in constant communication. Also, the creep prevention valve 52
The spring chamber 60 is always in communication with an output oil passage 59 of a switching valve 70, which will be described later. Further, a feedback oil passage 67 branches from the output oil passage 14a, and is connected to the creep prevention valve 5 via the solenoid valve 56 and oil passage 66.
The valve body 53 communicates with the discharge passage 63 of No. 2 so as to be openable and closable.

The solenoid valve 56 is connected to a brake sensor 81, a vehicle speed sensor 82, and a water temperature sensor 83 via an AND circuit 80. These sensors 8
1 to 83 determine the conditions for generating the creep prevention function, and the bracer sensor 81 outputs a high level signal when the brake pedal is depressed, and may be a brake light switch, for example, and the vehicle speed sensor 82 outputs a high level signal when the brake pedal is depressed, and the vehicle speed sensor 82 outputs a high level signal when the brake pedal is depressed. For example, the water temperature sensor 83 may be composed of a magnet and a reed switch driven by a speedometer cable, and output a high level signal when the water temperature sensor 83 is below a reference value.
may be composed of, for example, a thermoferrite and a reed switch, which outputs a high level signal when the engine water temperature is above a reference value. In any case, when the brake pedal is depressed, the vehicle speed is below the reference value, and the engine water temperature is above the reference value, the output of the AND circuit 80 becomes a high level, and the solenoid valve 56 is energized. If the plunger 57 assumes the upper position shown in FIG. 2, i.e., the open position, and any one of the above conditions is not met, the solenoid valve 56 is deenergized and the plunger 57 assumes the lower position, i.e., the open position. Take closed position.

The valve body 71 of the switching valve 70 is constantly urged to the left in the drawing by a spring 72. Valve body 71
The right side of the valve body 71 forms a spring chamber 77 that communicates with the discharge oil passage 78, and the left side of the valve body 71 forms an operating chamber that communicates with the conduit 46 that supplies throttle pressure through a parallel circuit of a throttle valve 73 and a check valve 74. 76. Further, the central portion of the valve body 71 has a small diameter, and an annular cavity 71a is defined around its outer periphery.

Therefore, when the throttle pressure is not supplied from the pipe line 46, the valve body 71 is held in the left position by the biasing force of the spring 72, so that the oil passage 59 is closed to the annular cavity 7.
1a and the branch oil passage 79, it is completely communicated with the oil passage 46.

When throttle pressure is supplied from the oil passage 46, the valve body 71 moves to the right as shown in FIG. 4, and the throttle pressure is supplied to the oil passage 59 via the oil passage 46 and the check valve 75. However, at the same time, the line hydraulic pressure supplied from the oil passage 45 also flows into the annular cavity 71a.
It comes to be supplied to the oil path 59 through. Oil road 4
Since the line oil pressure Pl supplied from the oil passage 45 is higher than the throttle pressure supplied from the oil passage 46, the line oil pressure Pl supplied from the oil passage 45 closes the check valve 75. Therefore, the line oil pressure Pl in the oil passage 45 can be transmitted to the oil passage 59 without consuming much throttle pressure. That is, the switching valve 7
0, when the throttle pressure from the oil passage 46 rises, the throttle pressure supplied from the oil passage 46 is used as a pilot signal to control the line hydraulic pressure Pl of the oil passage 45.
It has the function of outputting to the oil passage 59.

Next, when the throttle pressure is lost from the oil passage 46, the hydraulic oil in the working chamber 76 is gradually discharged only through the throttle valve 73, so the valve body 77 gradually moves to the left, and finally In this case, the communication between the oil passage 45 and the oil passage 59 is cut off.

Next, the operating procedure of the vehicle transmission equipped with the creep prevention means according to the present invention will be explained, particularly regarding the creep prevention valve 52 thereof.

First, when the brake pedal is depressed, the vehicle speed is below the reference value, and the engine water temperature is above the reference value, that is, when it is desirable for the creep prevention state to occur, the solenoid valve 56 is energized. , the plunger 57 is in the upper or open position.

In this case, if no throttle pressure is generated in the oil passage 46, the pressure in the spring chamber 60 of the creep prevention valve 52 is low, so that the line hydraulic pressure Pl supplied from the oil passage 45 is directly and/or Since the valve body 53 acts on the lower end of the valve body 53 through , the valve body 53 moves upward. However, to some extent the valve body 5
3 moves upward, in this case, the oil passage 66 communicating with the oil passage 14a comes to communicate with the discharge oil passage 63, and at that time the input oil passage 45 is closed by the valve body 53, and the lower end of the valve body 53 is closed. The line hydraulic pressure applied is oil line 6.
9, the valve body 53 is in equilibrium in the position shown in FIG. That is, when the valve body 53 moves upward from the position shown in FIG. In order to descend, the valve body 53 moves downward,
Restore to the balanced position shown in Figure 3. On the contrary, the valve body 53
If Pl is lower than the position shown in FIG. and returns to the equilibrium position also shown in FIG. At this time, oil path 1
The hydraulic pressure P _ac held at 4a is the first gear clutch 1
4 is set at a pressure value that does not reach engagement, the first speed clutch 14 is in a disengaged state, and a creep prevention state is achieved.

This hydraulic pressure P _ac is the pressure receiving area of the lower end of the valve body 53,
It is determined by the line oil pressure, the spring force of the spring 58, etc. By actually screwing the adjustment screw 65,
When the coil spring 58 is compressed, the hydraulic pressure P _ac increases,
Conversely, if the adjustment screw 65 is screwed back, the spring force will be weakened and the oil pressure P _ac in the oil passage 14a will be lowered.

When throttle pressure is generated in the oil passage 46,
As mentioned above, the line hydraulic pressure Pl is also supplied from the oil passage 45 to the oil passage 59 via the switching valve 70, so the line hydraulic pressure Pl is also introduced into the spring chamber 60 from the control port 68, and the upper and lower ends of the valve body 53 are Due to the difference in pressure receiving area and the action of the spring force of the spring 58, the valve body 53 quickly descends. In this case, the input oil passage 45 is completely communicated with the output oil passage 14a, so that a creep recovery state is realized.

Next, consider the case where the solenoid valve 56 is demagnetized and the plunger 57 is in the lower, ie, closed, position.

When no throttle pressure is generated in the oil passage 46, the pressure in the oil passage 59 is low as described above, so the line oil pressure Pl supplied from the oil passage 45 is directly supplied from the input oil passage 45 of the creep prevention valve. Or via the bypass oil passage 69, the annular cavity 62 and the small hole 55
The liquid is supplied to the working chamber 61 through the valve body 53 and acts on the lower end of the valve body 53, so that the valve body 53 moves upward and assumes the upper position shown in FIG. In this state, the input oil passage 45 is closed by the valve body 53, so line oil pressure is supplied to the working chamber 61 via the throttle valve 54 of the bypass oil passage 69, the annular cavity 62, and the small hole 55. . However, unlike the above, the oil pressure of the oil 14a is not discharged through the oil passage 67, so the first speed clutch 14 is supplied with the line oil pressure Pl higher than the engagement pressure P _e .
Therefore, a creep recovery state is realized.

When throttle pressure is generated in the oil passage 46,
As described above, since the line hydraulic pressure Pl is supplied from the oil passage 59 to the spring chamber 60 via the control port 68, due to the difference in the pressure receiving areas at the upper and lower ends of the valve body 53 and the action of the spring force of the spring 58, The valve body 53 quickly descends. Also in this case, since the input oil passage 45 is always in communication with the output oil passage 14a, the creep recovery state continues.

As described above, when the solenoid valve 56 is energized and the throttle pressure increases by depressing the throttle, the creep prevention valve 52 is activated due to the function of the switching valve 70 in the initial stage of depressing the throttle pedal. The spring chamber 60 is pressurized in proportion to the throttle opening, and the operating pressure of the first speed clutch 14 also gradually increases until it reaches the line oil pressure Pl. At this time, since the creep recovery operation is performed by directly moving the valve body 53 of the creep prevention valve downward using line oil pressure, good responsiveness during sudden start can be maintained. On the other hand, if the throttle pedal is suddenly released, if the creep is removed immediately, the engine and transmission mount rubber will release the stored energy all at once, resulting in a large shock, so it is important to remove the creep. It is preferable to do this after some time has passed and the engine rotational speed has reached a sufficient level. As described above, when the switching valve 70 moves from the open position shown in FIG. 4 to the closed position shown in FIG.
Since the oil pressure is returned to the oil passage 46 through only the throttle valve 73, the creep recovery operation is performed slowly, thereby avoiding the above-mentioned inconvenience.

As described above, according to the present invention, even when the creep prevention operation is performed, the pressure P _ac lower than the engagement pressure P _e is constantly supplied to the first speed clutch 14, so that the creep recovery operation can be performed quickly. I can do it. Conversely, when the throttle is returned to shift to the creep prevention state, the creep prevention operation occurs gradually due to the function of the switching valve 70 described above, and no shock occurs.

Also, the solenoid valve 58 is broken and the plunger 5
7 is held in the lower position, the creep recovery state is always maintained, and conversely, if the plunger 57 is held in the upper position, that is, the open position, due to a failure of the solenoid valve 56, the state is maintained as described above. A creep prevention effect can be obtained in response to changes in the throttle pressure in the oil passage 46, and in any case, no particular trouble is caused.

Further, according to the present invention, since only one oil passage 59 is required to connect the creep prevention valve 52 and the switching valve 70, the switching valve 70 is provided with a solenoid or an adjustment mechanism inside the creep prevention valve 52. can be easily provided individually so as to fit on the outer surface of the transmission.

Although the present invention has been described above with reference to specific embodiments, various other embodiments are possible. For example, in the above embodiment, the operating pressure of the first speed clutch 14 is not allowed to flow into the throttle oil passage at all, but it is possible to flow a small flow rate within a range that does not disturb the throttle pressure, and the response can be improved. Switching that does not require much
For example, it can also be used for switching between the 3rd and 4th speed ranges. In this case, this can be easily handled by drilling a small diameter of, for example, about 0.5 mm in the axis of the valve body 71 of the switching valve 70. Furthermore, the type of creep prevention valve is not limited to one that isolates the first speed clutch from the hydraulic power source as shown in this embodiment, but is also shown in Japanese Patent Application No. 173,610/1985 by the same applicant. The present invention is equally applicable to such a type in which the oil passage supplying the working pressure of the first speed clutch is bypassed to the hydraulic tank.

Thus, according to the invention, it is possible to adjust the anti-creep device to accommodate manufacturing tolerances with a simple structure.

[Brief explanation of the drawing]

FIG. 1 is a hydraulic skeleton diagram showing a power transmission path of a vehicle automatic transmission equipped with creep prevention means according to the present invention. FIG. 2 is a circuit diagram schematically showing a hydraulic circuit for a vehicle automatic transmission equipped with creep prevention means according to the present invention. FIG. 3 is a partial view of the anti-creep valve of FIG. 2 with the valve body in the anti-creep position. Figure 4 shows the second valve in the closed position.
FIG. 3 is a partial view showing the switching valve shown in the figure. DESCRIPTION OF SYMBOLS 1... Engine, 2... Crankshaft, 3... Torque converter, 4... Auxiliary transmission, 5... Actuation device, 6, 6'... Wheels, 7... Pump impeller, 8
... Input shaft, 9 ... Rotor wheel, 10 ... Stator shaft, 11 ... One-way clutch, 12 ... Stator wheel, 13 ... Pump drive gear, 14 ... First
Speed clutch, 15... Drive gear, 16... Driven gear, 17... One-way clutch, 18... Output shaft,
19...Output gear, 20...Large diameter gear, 21...
Drive gear, 22... Second speed clutch, 23... Driven gear, 24... Drive gear, 25... Driven gear,
26... Third speed clutch, 27... Drive gear, 2
8... 4th speed clutch, 29... Driven gear, 30
... Reverse selector, 31 ... Reverse hub,
32... Drive gear, 33... Idle gear, 34
... Driven gear, 35 ... Oil tank, 26 ... Hydraulic pump, 37 ... Oil path, 38 ... Regulator valve, 39 ... Manual valve, 40 ... Oil path, 41
...Throttle valve, 42...Governor valve, 43...
1st-2nd speed shift valve, 45, 46, 47... Oil passage, 48... 2nd-3rd speed shift valve, 49... Discharge oil path, 50... 3rd-4th speed shift valve, 51... Discharge oil path, 52... Creep prevention valve, 53... Valve body, 54... Throttle valve, 55... Small hole, 56... Solenoid valve, 57... Plunger, 58... Coil spring, 59... Oil Road, 60... Spring chamber, 61...
... Working chamber, 62 ... Annular chamber, 63 ... Discharge oil path,
64...Filter, 65...Adjustment screw, 65a...
...Rocknut, 65b...Dust boots, 66
...Bypass oil passage, 67...Feedback oil passage, 68...Control port, 70...Switching valve, 71
... Valve body, 71a ... Annular chamber, 72 ... Coil spring, 73 ... Throttle valve, 74, 75 ... Check valve, 7
6... Working chamber, 77... Spring chamber, 78... Discharge oil path, 79... Branch oil path, 80... AND circuit, 8
1...Brake sensor, 82...Vehicle speed sensor, 8
3...Water temperature sensor.

Claims (1)

[Scope of Claims] 1. A fluid coupling, a power transmission means for transmitting the output torque of the fluid coupling, a hydraulically operated friction engagement means for controlling the power transmission capacity of the power transmission means, and the An automatic transmission for a vehicle is provided with a creep prevention means for variably controlling the power transmission capacity of the frictional engagement means, wherein the creep prevention means is connected in series with a conduit that supplies hydraulic pressure to the frictional engagement means. and a creep prevention valve that controls the input oil passage and the output oil in response to the differential pressure between the input oil passage, the output oil passage, the output oil pressure, and the throttle pressure, and the biasing force of a spring. a valve body that opens and closes communication between the input oil passage and the output oil passage; a throttle passage that constantly communicates the input oil passage with the output oil passage; and a throttle passage that starts closing communication between the input oil passage and the output oil passage. A feedback oil passage is provided that can communicate the discharge oil passage and the output oil passage by movement of a valve body, and the creep prevention means reduces the power transmission capacity of the frictional engagement means to a level that prevents creep. An automatic transmission for a vehicle, characterized in that a screw means is provided for adjusting the spring force of the spring in order to sometimes adjust the hydraulic pressure held in the frictional engagement means.