JPH1122813A - Hydraulic control device for automatic transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic control device for automatic transmission, which can prevent an engine from over-rotating in acceleration in the condition that the throttle is full open while the temp. is low. SOLUTION: A temp. compensation valve 30 to leak part of the throttle pressure to a drain part at the time of low temp. is installed at a throttle pressure input port of a 1-2 shift valve or a throttle pressure circuit in direct communication with the input port. The valve 30 is composed of a plug body 31 having a small coefficient of thermal expansion which seals one end of throttle pressure input port 16g and is equipped with communication holes 31b and 31c to put the port 16g in communication with the drain part and an aux. plug 32 which has a greater coefficient of thermal expansion and is equipped with a fit part 32b to be fitted in the communication hole 31b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic pressure control device for an automatic transmission, and more particularly to a hydraulic pressure correction structure at a low temperature.

[0002]

2. Description of the Related Art In recent years, aluminum is generally used for a valve body of a hydraulic control device in an automatic transmission, and iron or the like having a smaller thermal expansion coefficient than aluminum is used for a valve. Therefore, a hydraulic pressure leak occurs due to the difference between the two coefficients of thermal expansion.

[0003]

FIG. 1 shows an example of a shift diagram of an automatic transmission having four forward speeds. The shift point, that is, the switching point of the shift valve, is determined by the relative relationship between the governor pressure in proportion to the vehicle speed and the throttle pressure in proportion to the throttle opening, but is usually adjusted to match the set value at normal temperature. . However, when the temperature is low, the viscosity of the oil is high and the leak of the oil is reduced, so that the throttle pressure increases and the shift point shifts to a higher vehicle speed side. Therefore, when the vehicle is accelerated in the first speed state and the throttle opening fully open at a low temperature, the first speed state is maintained despite the region where the second speed state is supposed to be as shown by the diagonal line in FIG. There was a problem of becoming a state.

To solve this problem, Japanese Patent Application Laid-Open No. 7-54982 proposes a device provided with a pressure adjusting means for maintaining a line pressure regulated by a pressure reducing valve at a constant value even at a low temperature. However, in this case, since the line pressure is merely maintained at a constant value, it is not always possible to reliably prevent the engine overspeed phenomenon when accelerating at the full throttle opening in the first speed state.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a hydraulic control device for an automatic transmission, which can reliably prevent the engine from rotating excessively during acceleration at full throttle opening at low temperatures.

[0006]

In order to achieve the above object, the present invention provides a throttle pressure input port of a 1-2 shift valve or a throttle pressure circuit which directly communicates with this port, and a part of the throttle pressure at a low temperature. A temperature compensating valve for leaking to the drain portion is provided.

At normal temperature, the temperature compensating valve is closed and a certain amount of throttle pressure leaks from the throttle pressure circuit, so that it can be made to coincide with a predetermined shift point. On the other hand, when the temperature is low, the amount of leakage from the throttle pressure circuit decreases, so the throttle pressure rises.However, since a part of the throttle pressure leaks from the temperature compensation valve to the drain portion, the shift point shifts to a higher vehicle speed side. Can be prevented. Therefore, at the time of full-open acceleration, the second speed state is quickly established, and excessive rotation of the engine can be prevented. In the present invention, the purpose of the present invention is to prevent the shift point at the time of shifting from the first gear to the second gear from shifting to the higher vehicle speed side.
-2 It must be provided at a location that directly affects the throttle pressure input to the shift valve. Therefore, 1-2
It may be provided in the throttle pressure input port of the shift valve or a throttle pressure circuit directly communicating with this port.

According to a second aspect of the present invention, a plug body having a small thermal expansion coefficient is provided with a communication hole for sealing the temperature compensating valve at one end of a port to which a throttle pressure is input and communicating the port with a drain portion. And an auxiliary plug having a large thermal expansion coefficient having a fitting portion fitted to the communication hole,
It is preferable that a part of the throttle pressure be leaked to the drain portion from a gap between the communication hole of the plug body and the fitting portion of the auxiliary plug at a low temperature. In this case, it is not necessary to change other oil passages and valve shapes only by replacing the plug, so that a temperature-compensated circuit can be easily configured.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 shows an example of an automatic transmission having four forward speeds, and includes a torque converter 1, an input shaft 2 to which engine power is transmitted via the torque converter 1, and three clutches. C1, C2, C3, band brakes b1, B2 brake, servo piston 3 for engaging and releasing band brake b1, Ravigneaux type planetary gear mechanism 4,
It includes a one-way clutch OWC, an output gear 5, an output shaft 7, a differential device 8, and the like.

The forward sun gear 4a of the planetary gear mechanism 4
And the input shaft 2 are connected via a C1 clutch.
The rear sun gear 4b and the input shaft 2 are connected via a C2 clutch, and the carrier 4c and the input shaft 2 are connected via a C3 clutch. The carrier 4c is connected to a fixing member 6 such as a casing via a B2 brake and a one-way clutch OWC that allows only the forward rotation (engine rotation direction) of the carrier 4c. The carrier 4c supports two types of pinion gears 4d and 4e, the forward sun gear 4a meshes with a long pinion 4d having a long shaft length, and the rear sun gear 4b has a short pinion 4 having a short shaft length.
and e is engaged with the long pinion 4d. The ring gear 4f that meshes with only the long pinion 4d is connected to the output gear 5. The output gear 5 is connected to a differential 8 via an output shaft 7.

The power transmission mechanism includes clutches C1, C
2, C3, brakes b1, B2, and one-way clutch OWC, as shown in FIG.
It realizes the first gear. In FIG. 3, ○ indicates the operating state of the hydraulic pressure. B1 is the servo piston 3
B1 'indicates a release-side oil chamber of the servo piston 3. When hydraulic pressure is guided to both oil chambers B1 and B1' (at the third speed), the band brake b1 is released. You. FIG. 3 shows only the D range and the R range, but the L, 2, N, and P ranges are omitted.

FIG. 4 shows an example of a hydraulic control device in the automatic transmission. This hydraulic control device includes an oil pump 1
0, primary regulator valve 11, manual valve 12, throttle valve 13, 1-2 shift valve 14, 2-3 shift valve 15, 3-4 shift valve 1.
6, governor valve 17, throttle modulator valve 18, 4-2 timing valve 19, 2-4 timing valve 20, 3-2 timing valve 21, servo control valve 22, 4-3 timing valve 23, release control valve 24, C1 accumulator 2
5, C2 accumulator 26, B1 accumulator 27
And so on. In the above hydraulic control device, the configuration other than the throttle valve 13, the 1-2 shift valve 14, and the 3-4 shift valve 16 is not directly related to the present invention.
Detailed description is omitted.

FIG. 5 shows a hydraulic circuit of a main part of the present invention.
As is well known, the throttle valve 13 is a valve that generates a hydraulic pressure (throttle pressure _PT ) proportional to the throttle opening, and has a structure in which a spring 13c is interposed between the plunger 13a and the spool 13b. . The spool 13b is urged from the opposite direction by another spring 13d. Line from the port 13e pressure P _L is input, the throttle pressure P _T from the port 13f is output.
Incidentally, the throttle pressure P _T is fed back to the port 13 g, when the plunger 13a is pressed more than a certain amount (e.g., when the kick-down), taken from the port 13h to output a kickdown pressure P _K (= P _T) I have.

[0014] 1-2 shift valve 14 and the first speed position by a relative relationship between the governor pressure P _G and the throttle pressure P _T 2 to 4
The valve is switched to the high speed position, and the spring 14a
And a spool 14b urged from one side by the drive shaft. The governor pressure PG is input to the right end port 14c in a direction opposite to the spring 14a, and the throttle pressure P _G is applied to the port 14d from the throttle valve 13 via the oil passage 35.
_T is input to the governor pressure P _G and the opposite direction. Also,
The input port 14e is input line pressure P _L, is drained from the output port 14f to the first speed, and outputs the line pressure P _L at 2-4 speed. Incidentally, the port 14g is input from the throttle valve 13 is kickdown pressure P _K, biases the spool 14b in the direction opposite to the governor pressure P _G.

Further, a valve is switched to the 1-3 speed position and the fourth speed position by a relative relationship between the 3-4 shift valve 16 is also governor pressure P _G and the throttle pressure P _T, the spool 1
A spring 16c is provided between 6a and plunger 16b. The plunger 16b is urged rightward by another spring 16d. Right end ports 16e, 16f
Governor pressure P _G which urges the spool 16a to the left is input to the port 1 of the left side housing the spring 16d
A throttle pressure _PT for urging the plunger 16b rightward is input to 6g from the throttle valve 13 via an oil passage 35. The line pressure P is applied to the input port 16h.
_L is input, the drain from the output port 16i to the first speed, and outputs the line pressure P _L at 2-4 speed.

The port 16g of the 3-4 shift valve 16 to which the throttle pressure _PT is input is provided with a temperature compensating valve 30 which constitutes a main part of the present invention. As shown in FIG. 6, the compensating valve 30 includes a plug body 31 having a relatively small coefficient of thermal expansion such as iron for sealing one end of the port 16g, and an auxiliary plug 32 having a relatively large coefficient of thermal expansion such as aluminum. It is composed of The materials of the plug main body 31 and the auxiliary plug 32 are not limited to iron and aluminum, but are desirably selected in accordance with the thermal expansion coefficient ratio between the spools 14b, 16a and the valve body.

The inner end face of the plug body 31 facing the port 16g has a radially extending communication groove 31a as shown in FIG.
Is formed at the shaft center, and a communication hole including a large-diameter hole 31b and a small-diameter hole 31c is formed. Therefore, port 1
A part of the throttle pressure _PT of 6 g can leak from the communication groove 31a to the drain portion 33 through the large diameter hole 31b and the small diameter hole 31c. The plug body 31
Is locked by engaging a pin 34 inserted from the outside with the peripheral groove 31d.

The auxiliary plug 32 has a function of a spring receiver for the spring 16d housed in the port 16g.
The flange portion 32a is pressed against the end face of the plug body 31 where the communication groove 31a is formed by the spring force of the spring 16d. Since the outer diameter of the flange portion 32a of the auxiliary plug 32 is slightly smaller than that of the plug body 31, the communication groove 31a
Is always in communication with the port 16g. On the inner side surface of the auxiliary plug 32, a convex portion 32b that fits into the large-diameter hole 31b is provided in a protruding manner.
The clearance of b is set to almost zero. Therefore, the throttle pressure _PT does not leak at normal temperature and high temperature.

The operation of the temperature compensation valve 30 will now be described. At normal temperature, the convex portion 32b of the auxiliary plug 32 is tightly fitted in the large-diameter hole 31b of the plug body 31, so that the throttle pressure _PT does not leak to the drain portion 33. Therefore, the throttle pressure _PT does not decrease, and the shift valves 14 to 16 are switched at a preset shift point,
A desired shift can be performed. On the other hand, when the temperature is low, the viscosity of the oil is high and the leak of the oil is reduced, so that the throttle pressure _PT increases and the shift point shifts to the higher vehicle speed side. However, at low temperatures, the convex portion 32b of the auxiliary plug 32 having a large thermal expansion coefficient shrinks more largely than the large-diameter hole 31b of the plug body 31 having a small thermal expansion coefficient, so that the clearance between the convex portion 32b and the large-diameter hole 31b increases. . Therefore, a part of the throttle pressure _{PT at} the port 16g is leaked from the communication groove 31a to the drain portion 33 through the large-diameter hole 31b and the small-diameter hole 31c, thereby offsetting the increase in the throttle pressure _PT . This leak amount can be adjusted by providing a notch (notch) or the like in the length of the protrusion 32b or the protrusion 32b or the large-diameter hole 31b. Therefore, the 1-2 shift valve 1
The throttle pressure _PT acting on the fourth port 14d is substantially equal to that at normal temperature, so that the shift point can be prevented from shifting to the high vehicle speed side. As a result, when the vehicle is accelerated in the first speed state and the throttle opening is fully opened, the state is quickly changed to the second speed state in a region indicated by oblique lines in FIG. 1, and it is possible to prevent the engine from becoming overspeed.

FIG. 8 shows a second embodiment of the temperature compensating valve of the present invention. This temperature compensating valve 40 is also a plug-type compensating valve arranged at the throttle pressure input port 16g of the shift valve 16 similarly to FIG.
And A communication hole 41 a for communicating the throttle pressure input port 16 g with the drain portion 33 is formed in the axis of the plug body 41. The bimetal 42 includes an annular portion 42a against which the spring 16d is pressed and a communication hole 41.
a that opens and closes the valve a. The valve 42b bends due to a temperature change. If the temperature is equal to or higher than the normal temperature, the valve portion 42b
Has closed the communication hole 41a, and the throttle pressure _PT does not leak. At low temperatures, the valve 4
2b bends in the plate thickness direction to open the communication hole 41a, causing a part of the throttle pressure _PT to leak, thereby suppressing an increase in the throttle pressure _PT .

FIG. 9 shows a third embodiment of the temperature compensating valve according to the present invention. The temperature compensating valve 50 utilizes the viscosity of oil, and is provided in the middle of the throttle pressure supply oil passage 35. The compensating valve 50 is movable in the axial direction in the supply oil passage 35, and has a valve body 51 having an orifice hole 51a at the axial center.
, A spring 52 for urging the valve body 51 in a direction opposite to the direction of action of the throttle pressure _PT , and a drain oil passage 53 branched from the supply oil passage 35. At normal temperature, the viscosity of the oil is low, so the throttle pressure _PT is
The valve element 51 closes the drain oil passage 53 by the spring force of the spring 52. At low temperatures, the viscosity of the oil increases, and the valve body 51
The oil passing through the orifice hole 51a receives a resistance and urges the valve body 51 in the compression direction of the spring 52 by the reaction force. Therefore, the drain oil passage 53 is opened, and a part of the throttle pressure _PT is drained. The drain oil passage 5
When the valve 3 is opened, an orifice 54 is provided in the drain oil passage 53 so that the throttle pressure _PT does not drop sharply.

The present invention is not limited to the above embodiment. In the first and second embodiments, the temperature compensating valves 30 and 40 utilizing the coefficient of thermal expansion are provided in the throttle pressure input port 16g of the 3-4 shift valve 16, but these temperature compensating valves are connected to the throttle pressure supply oil passage 35. Alternatively, it may be provided at a throttle pressure input port of the 1-2 shift valve 14 or the like. However, when a plug is used, the throttle pressure input port needs to be provided at the end of the valve. The present invention is applicable not only to a mechanical automatic transmission but also to an electronically controlled automatic transmission. Of course, the gear is 4
It is not limited to speed.

[0023]

As is apparent from the above description, according to the present invention, since the temperature compensating valve for leaking a part of the throttle pressure to the drain portion at the time of low temperature is provided, the rise of the throttle pressure at low temperature is offset. In addition, it is possible to prevent the shift point from shifting to the high vehicle speed side. Therefore, the second speed state is quickly established at the time of full-open acceleration, and the overspeed of the engine can be prevented.

[Brief description of the drawings]

FIG. 1 is a shift diagram as a premise of the present invention.

FIG. 2 is a schematic diagram of an automatic transmission having a fourth forward speed.

FIG. 3 is a table showing the operation of each friction element.

FIG. 4 is an overall circuit diagram of a hydraulic control device according to the present invention.

FIG. 5 is a circuit diagram of a main part of the hydraulic control device according to the present invention.

FIG. 6 is a detailed view of a temperature compensation valve.

FIG. 7 is a perspective view of a plug body of the temperature compensation valve.

FIG. 8 is a perspective view of a second embodiment of the temperature compensation valve.

FIG. 9 is a sectional view of a third embodiment of the temperature compensation valve.

[Explanation of symbols]

 14 1-2 shift valve 14d throttle pressure input port 16 3-4 shift valve 16g throttle pressure input port 30 temperature compensating valve 31 plug body 31b large diameter hole (communication hole) 32 auxiliary plug 32b convex part (fitting part) 33 drain Part 35 Throttle pressure supply oil passage

Claims (2)

[Claims] A temperature compensating valve is provided in a throttle pressure input port of a 1-2 shift valve or a throttle pressure circuit directly communicating with this port to leak a part of the throttle pressure to a drain portion at a low temperature. Automatic transmission hydraulic control device. 2. A plug body having a small thermal expansion coefficient, comprising a communication hole for sealing the temperature compensating valve at one end of a port to which a throttle pressure is input, and communicating the port with a drain portion. An auxiliary plug having a large thermal expansion coefficient having a fitting portion that fits into the hole, and at a low temperature, a part of the throttle pressure from the gap between the communication hole of the plug body and the fitting portion of the auxiliary plug to the drain portion. 2. The hydraulic control device for an automatic transmission according to claim 1, wherein the hydraulic pressure is caused to leak.