JPS60179552A - Hydraulic control device of automatic speed changer - Google Patents

Abstract

PURPOSE:To prevent the pressure drop of oil in a speed changer and a decrease of its responsive speed, by increasing the delivery pressure of an oil pump in a range of high throttle pressure when the oil is at a high temperature while the delivery pressure of the oil pump in the whole range when the oil is at a low temperature. CONSTITUTION:A regulator valve 10 provides the first temperature sensing member 16 with action for the delivery pressure of an oil pump 20 tending to increase when a temperature is lower than the first predetermined value, while a pressure-regulating valve 30 provides the second temperature sensing member 40 with action for the fixed pressure tending to increase when the temperature is higher than the second predetermined value. In this way, the pressure drop of oil due to its leak can be prevented by icreasing a maximum value of the line pressure when the oil is at a high temperature, while a trouble due to the delay of responsive speed on the basis of an increase of viscosity of the oil can be eliminated by increasing the line pressure over the whole range when the oil is at a low temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field The present invention relates to a hydraulic control device for an automatic transmission.

(b) Prior art As a conventional hydraulic control device for an automatic transmission that regulates the oil pump discharge pressure, for example, JP-A No. 57-144338,
There is one shown in ``Shift Device of Automatic Transmission'' (February 26, 1981, 1i'#).

This hydraulic control device for an automatic transmission includes a pressure modifier valve that adjusts throttle modifier pressure based on throttle pressure, and a regulator valve that adjusts oil pump discharge pressure according to throttle modifier pressure. There is. The throttle modifier pressure is equal to the throttle pressure when the throttle pressure is below a certain pressure, and is not greater than the constant pressure when the throttle pressure is above the certain pressure (i.e.
The throttle modifier pressure is equal to the throat pressure until the throttle pressure reaches a constant pressure, and when the throttle pressure is higher than the constant pressure, the throttle modifier pressure becomes a constant pressure that is smaller than the throttle pressure. With this configuration, the oil pump discharge pressure (line pressure) increases according to the throttle pressure when the throttle pressure is below a certain pressure, and remains at a constant value when the throttle pressure is higher than the certain pressure. The pressure is adjusted so that

However, conventional hydraulic control devices for automatic transmissions were not equipped with a device to correct the pressure regulation function according to the oil temperature, so as the oil temperature increases, the viscosity of the oil decreases, causing oil to leak from gaps in valves, etc. In some cases, the specified oil pressure may or may not be obtained, and conversely, when the oil temperature is low, the viscosity of the oil increases, increasing the resistance of the oil path and impeding the response of hydraulic control. The speed decreases (for example, if the response speed of the regulator valve decreases, the rise in oil pump discharge pressure will be delayed in response to the increase in engine output when the vehicle starts rapidly, causing clutch, brake, etc. to slip, etc.) Therefore, there was a problem that it was difficult to satisfy both requirements.

(c) Purpose of the invention The present invention prevents oil pressure from decreasing at high temperatures.
In addition, hydraulic control equipment for automatic transmissions that does not cause insufficient hydraulic pressure due to a decrease in the response speed of hydraulic control at low temperatures;
The purpose is to obtain. □(d) Structure of the Invention The present invention increases the oil pump discharge pressure only in the high throttle pressure range when the oil temperature is high, and increases the oil pump discharge pressure in the entire throttle pressure range when the oil temperature is low. The above purpose is achieved by increasing the pressure. For this purpose, in the present invention, a spring using a temperature-sensitive member whose phase changes depending on the temperature is used for both the regulator valve and the pressure modifier valve. That is, the hydraulic control device for an automatic transmission according to the present invention uses the throttle pressure that changes in accordance with the output of the engine as the hydraulic pressure source, and when the throttle pressure is below a certain pressure, uses the hydraulic pressure equal to the throttle pressure as the throttle modifier pressure. and a pressure modifier valve that outputs the constant pressure as a throttle modifier pressure when the throttle pressure is higher than a constant pressure, and the throttle modifier pressure from the pressure modifier valve is used as a control signal hydraulic pressure to discharge an oil pump. and a regulator valve that regulates the pressure, and the regulator valve is provided with a first temperature-sensitive member that applies a force in a direction to increase the oil pump discharge pressure when the temperature is lower than a first predetermined value. The pressure modifier valve is provided with a second temperature sensitive member that applies a force in a direction to increase the constant pressure when the temperature is higher than a second predetermined value.

``(E) Embodiments Embodiments of the present invention will now be described with reference to FIGS. 1 to 3 of the accompanying drawings.

The regulator valve 10 includes a spool 14 inserted into a valve hole 12, a (first) shape-memory alloy spring 16 (first temperature-sensitive member) disposed at the upper end of the spool 14 in FIG. l on the lower side of the spool 14 in the figure! i! The spring 18 to be placed is on the right. The valve hole 12 has ports 12a-12f. Bo) 12a, 1
2c is a drain boat. Ports 12b and 12
d is connected to a line pressure oil passage 22 to which oil discharged from the oil pump 20 is supplied. Bow 1-12e is a port from which oil is discharged from port 12d, and this bow) 1
The oil discharged to 2e is supplied to, for example, a torque converter via an oil passage 24. Ports 12 and 3 are ports 32a and 3 of a pressure modifying valve 30', which will be described later.
It is connected to 2c. Sp, -le 14 is land 14a
~14d. Lands 14b, 14c and 14
d have the same diameter, and the land 14a has a smaller diameter than these.

The six springs 18, to which the hydraulic pressure of bow 12b acts on the pressure-receiving portion formed between the lands 14a and 14b, exert constant forces on the spool 14 in two directions in FIG. The shape-memory alloy spring 16 is used when the temperature of the hydraulic fluid of the automatic transmission is constant (for example, 80°
Before and after C), a relatively large downward force is applied to the spool 14 in FIG.
For example, if the temperature is lower than 20° C., it contracts so that the force acting on the spool 14 becomes smaller.

The pressure modifier valve 30 has a valve hole 32
and the spool 34 charged in the spool 34 in FIG.
A spring 36 disposed above the spool 34 in FIG. 1, a spring 38 disposed below the spool 34 in FIG. 1, and a (second) shape memory alloy spring 40 (second temperature-sensitive member).
It has . Valve hole 32 is po) 32a to 32
It has e. The port 32a and the port 32c communicate with the port 12f of the leg and lake pulp 10 via the oil passage 26. A throttle pressure that changes in accordance with the engine output is supplied to the port 32b through an oil passage 42. 32d and 32e are drain boats. The spool 34 has lands 34a and 34b of the same diameter. The axial dimension of the groove between lands 34a and 34b is approximately equal to the wall distance between ports 32b and 32d. The spooling ring 38 is connected to the spool 34 by the 11th. A constant upward force is acting in J.

The shape memory alloy spring 4o exerts a relatively small upward force when the oil temperature is in a steady state of use, but when the oil temperature becomes higher than the (i'th) predetermined value (for example, 120° C.), The spool 34 is extended in the axial direction so that the force acting on the spool 34 is increased. spring 36
is designed to always exert a constant downward force on the spool 34, and this downward force is designed to be approximately equal to the force when the shape memory alloy spring 40 is at a temperature in a steady state of use. be.

Next, the operation of this embodiment will be explained.

Ma-zu=? 11] If the temperature is in steady use,
The force of the shape memory alloy spring 40 of the pressure modifier valve 30 is relatively small and balanced with the force of the spring 36, so the pressure modifier valve 30 performs a pressure regulating action based on the force of the spring 38. That is, when the throttle pressure is low, the spool 34 is in the state shown in the left half of FIG.

When the throttle pressure becomes higher than a constant pressure, port 32
The spool 34 is pushed down to the position shown in the right half of FIG.
is in a slightly opened state, and the pressure modifier valve 30 is in a pressure regulating state. The regulated oil pressure has a constant value corresponding to the horn of the spring 38, and this constant pressure is supplied to the oil path 26. That is, the oil pressure in the oil passage 26 (hereinafter, this oil pressure will be referred to as throttle modifier pressure) changes as shown by the solid line in FIG. 2 in accordance with the throttle pressure. The throttle modifier pressure of this oil passage 26 is the regulator pulse 7'IO port'
12 acts on f. The regulator valve IO discharges oil from the port 12d to the ports 12e and 12c to perform a pressure regulating action so that the oil pressure at the bow 12b changes in accordance with this throttle modifier pressure. In this case, since the oil temperature is in a steady state of use, the shape memory alloy spring 16 acts on the spool 14 with a relatively large force. Due to the above-described pressure regulating action of the regulator/help 1o, the oil pump discharge pressure (line pressure) has characteristics as shown by the solid line in FIG. 3. The line pressure characteristics shown in FIG. 3 are regular characteristics that serve as a reference, and the torque capacities of friction elements such as clutches and brakes are determined based on these characteristics.

Next, the effect when the oil rises to level 1 will be explained. When the oil temperature is higher than the normal usage condition (Example L t!, 1
20℃ or higher), pressure modifier valve 30
The force of the shape memory alloy spring 4o becomes thicker. Therefore, the constant pressure regulated by the pressure modifier valve 30 becomes higher. That is, the throttle modifier pressure in the oil passage 26 obtained by the pressure modifier valve 30 has characteristics as shown by the broken line in FIG. Since the regulator valve 10 performs a pressure regulating action using the throttle modifier pressure having such characteristics, the line pressure has characteristics as shown by the broken line in FIG. 3. In this case, the shape memory alloy spring 16 of the regulator valve 10 is not affected by the rise in oil temperature, so it exerts the same force as when the oil temperature is in a steady state. In the line pressure characteristics shown by the broken line in FIG. 3, only the line pressure in the region where the throttle pressure is large is higher than the reference characteristic (the characteristic shown by the solid line in FIG. 3). In other words, the line pressure is increased in the high throttle pressure region where the line pressure may decrease due to a decrease in viscosity due to a rise in temperature, and even if there is a slight decrease in line pressure due to oil leakage, the line pressure is increased to the minimum. This is to ensure that the necessary hydraulic pressure is maintained. Moreover, in this case, in the region where the throttle pressure is small, the base 4+! The line pressure characteristics are as expected.
There are no side effects such as increased musculature.

Next, the effect when the oil temperature is very low will be explained. When the oil temperature is very low (eg, lower than 20° C.), the force of the shape memory alloy spring 16 of the regulator valve 10 is smaller than when the oil temperature is in a steady state. For this reason, the downward force acting on the spool 14 in FIG. 1 becomes smaller, and the oil pressure of the port h12b increases to compensate for this. That is, the line pressure regulated by the regulator valve 10 increases. In this case, the shape memory alloy spring 40 of the pressure modifier valve 30 is in the same state as when the oil temperature is in a steady state, and the characteristics of the throttle modifier pressure in the oil passage 26 are shown by the solid line in FIG. The state is shown by.

Therefore, the line pressure characteristics obtained by the C curator valve IO are those in which the line pressure is increased over the entire throttle pressure range, that is, the characteristics shown by the dashed line in FIG. 3. When the oil temperature is low, this third
As shown in the characteristic shown by the dashed line in the figure, since the line pressure is increased over the entire throttle/torque pressure range, the response speed of hydraulic control is delayed due to the increased viscosity of the oil, resulting in an increase in line pressure. Even if there is some delay, a lack of oil pressure will not occur. Therefore, it is possible to prevent the clutch and brake from slipping during a sudden start.

As a result, due to the above action, when the oil temperature is high, only the maximum line pressure can be increased, and when the oil temperature is low, the entire line pressure can be increased to prevent oil leakage at high temperatures. Also, problems associated with delays in control response speed at low temperatures can be simultaneously resolved without causing any side effects. Note 1. In the second embodiment, a shape memory alloy spring is used as the temperature sensitive member, but the spring is not limited to this, and a material that causes a phase change, such as wax, may be used in the bellows.

(f) As described in detail, according to the present invention, the throttle pressure that changes in accordance with the output of the engine is used as the hydraulic pressure source, and when the throttle pressure is less than a certain pressure, the oil pressure equal to the throttle pressure is applied to the throttle. A pressure modifier valve that outputs the constant pressure as a throttle modifier pressure when the throttle pressure is higher than a constant pressure, and a pressure modifier valve that outputs the constant pressure as a throttle modifier pressure, and the throttle modifier pressure from the pressure modifier valve is used as a control signal oil pressure. A hydraulic control device for an automatic transmission having a regulator valve that regulates pump discharge pressure,
The regulator valve has a temperature at a first predetermined value (for example, 2
A first temperature sensing member (16) that changes phase according to the oil temperature is provided so as to apply a force in the direction of increasing the oil pump discharge pressure when the temperature is lower than 0°C. When the temperature is higher than a predetermined value of ffr12 (for example, 120°C), the constant pressure is applied to the valve.
Since the second temperature-sensitive member (40) that changes phase according to the oil temperature is provided so as to apply a force in the direction of raising the oil temperature,
If the oil temperature is high, increase the maximum line pressure to prevent oil pressure from dropping due to oil leakage.

In addition, when the oil temperature is low, the line pressure can be increased over the entire range to eliminate problems caused by delays in response speed due to increased oil viscosity. In addition to the above-mentioned effects, the embodiment in which the temperature-sensitive member is a shape-memory alloy sprung ring is particularly advantageous in terms of cost and space.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a hydraulic control device for an automatic transmission according to the present invention;
FIG. 2 is a diagram showing the characteristics of throttle modifier pressure, and FIG. 3 is a diagram showing the characteristics of line pressure. io-@・regulator valve, 12°″″ valve hole,
14- @ Spool, 16... (No. ■) Shape memory alloy spring, 18... Spring, 20...φ oil pump, 24.26... Oil m, 30--φ Pressure modifier pulp , 32... Valve hole, 34
Spool, 36φmm spring, 38--- Spring, 40... (2nd) Shape memory alloy spring, l] San Jidosha Co., Ltd. 5f Toshiyuki Miyauchi, Physician Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. A hydraulic pressure source is a throttle pressure that changes in accordance with the output of the engine, and when the throttle pressure is less than a certain pressure, a hydraulic pressure equal to the throttle pressure is output as a throttle modifier pressure, and the throttle pressure is When the pressure is higher than the constant pressure, the pressure modifier valve outputs the constant pressure as the throttle modifier pressure, and the throttle modifier pressure from the pressure modifier valve is controlled as the oil pump discharge pressure. In a hydraulic control device for an automatic transmission, the regulator valve is configured to apply a force to increase the oil pump discharge pressure when the temperature is lower than a first predetermined value. A first temperature-sensitive member whose phase changes depending on the temperature is provided, and the pressure modifier valve is configured to apply a force in a direction to increase the constant pressure when the temperature is higher than a second predetermined value. A hydraulic control device for an automatic transmission, characterized in that a second temperature-sensitive member whose phase changes depending on oil temperature is provided. 2. The hydraulic control device for an automatic transmission according to claim 1, wherein the first and second temperature-sensitive members are springs made of a tQ alloy.