JPH01275942A - Oil pressure control valve - Google Patents

Abstract

PURPOSE:To steeply change output oil pressure only within a fixed range of signal oil pressure by attaching a plunger which can move relatively to a spool as far as a fixed distance and partially receive signal oil pressure to a signal oil pressure port, and providing a spring to energize the plunger in a direction opposite to the signal oil pressure. CONSTITUTION:In the case where signal oil pressure Ps is below a certain value, the motion of a plunger 4 is checked by a spring force of a spring 5. The signal oil pressure Ps acting on a pressure face of a spool 2 therefore balances with output oil pressure returned to an output oil pressure return port 11, and the ascending slope of the output oil pressure P to the signal oil pressure Ps is gentle. In the case where the signal oil pressure Ps exceeds the certain value, the plunger 4 moves to abut on the spool 2, and the signal oil pressure Ps acts on the sum of the pressure areas of the plunger 4 and of the spool 2, and the ascending slope of the output oil pressure P to the signal oil pressure Ps becomes steeper to increase the output oil pressure.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a hydraulic control valve that controls output hydraulic pressure according to a signal hydraulic pressure, and particularly relates to a hydraulic control valve suitable for thrust control of a belt-type continuously variable transmission. It is.

[Prior art and its problems] Conventionally, as a hydraulic control valve suitable for speed change control of a belt-type continuously variable transmission, the one described in Japanese Patent Application Laid-open No. 196482/1982 is known. This hydraulic control valve includes a spool that selectively communicates an output hydraulic port and an input hydraulic port or a drain port, a spring that biases the spool in one direction, and a spring that biases the spool in the opposite direction to the spring. The signal hydraulic pressure is guided so that the spool is biased in the same direction as the spring, and the output hydraulic pressure is guided so that the spool is biased in the same direction as the spring. In the hydraulic control valve having the above structure, since the output hydraulic pressure is fed back, the pulsation of the output hydraulic pressure is small, and highly accurate hydraulic control can be performed, and there is an advantage that the influence of the residual pressure of the signal hydraulic pressure can be eliminated.

By the way, in a belt-type continuously variable transmission, during kickdown or coastdown (when downshifting due to deceleration), it is necessary to rapidly increase the oil pressure of the driven pulley to quickly shift to a low speed ratio. be. However, in the above hydraulic control valve, the output hydraulic pressure changes proportionally according to the signal hydraulic pressure, so it is not possible to rapidly increase the output hydraulic pressure only within a predetermined signal hydraulic range, and the hydraulic control valve is connected to the driven pulley. Even when used as a control valve, the required kickdown performance and coastdown performance cannot be obtained.

Therefore, the proportional gradient between the signal oil pressure of the hydraulic control valve and the output oil pressure must be set thick in advance, but this will cause the output oil pressure to change rapidly even in normal operating ranges other than during kink down or coast down. Therefore, there is a problem that control accuracy in the normal operating range is reduced.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned problems.The purpose of the present invention is to provide a hydraulic control valve that can sharply change the output oil pressure only within a predetermined signal oil pressure range and gently change the output oil pressure in other ranges. Our goal is to provide the following.

[Structure of the Invention] In order to achieve the above object, the present invention provides an input hydraulic port to which input hydraulic pressure is input, a drain port, and a drain port formed at an intermediate portion between the input hydraulic port and the drain port to output hydraulic pressure. an output hydraulic pressure port to which the signal hydraulic pressure is input to push the spool in one direction, and an output hydraulic pressure return port to which the output hydraulic pressure is returned to push the hesbourg in the opposite direction to the signal hydraulic pressure. In the hydraulic control valve, the signal hydraulic pressure port is provided with a plunger that is movable relative to the spool by a certain distance and receives a portion of the signal hydraulic pressure, and the plunger is moved in a direction opposite to the signal hydraulic pressure. It is characterized by providing a biasing spring.

[Effect]

If the signal oil pressure is below a certain value, the plunger cannot operate due to the spring force of the spring, so the signal oil pressure acting on the pressure receiving surface of the spool is balanced with the output oil pressure returned to the output oil pressure return port, and the signal oil pressure is The rising slope of the output oil pressure is gradual.

In addition, when the signal oil pressure exceeds a certain value, the plunger operates and comes into contact with the spool, and the signal oil pressure acts on the sum of the pressure receiving areas of the plunger and spool, so the upward slope of the output oil pressure with respect to changes in the signal oil pressure becomes high, and the output oil pressure increases rapidly. In this way, the output hydraulic characteristics of the hydraulic control valve are non-linear, so when this hydraulic control valve is applied to the driven pulley of a V-belt continuously variable transmission, highly accurate hydraulic control is possible in the normal operating range. During kickdown or coastdown, the output oil pressure is suddenly increased, allowing for agile downshifts.

〔Example〕

FIG. 1 shows a first embodiment of a hydraulic control valve A according to the present invention, in which a spool 2 is slidably disposed inside a valve body 1, and the spool 2 is always biased to the left by a first spring 3. has been done. Further, a plunger 4 is slidably disposed inside the left end of the spool 2, and a second spring 5 that always biases the plunger 4 to the left is disposed to penetrate the spool 2.

From the left side, the valve body 1 includes a signal hydraulic port 6 to which a signal hydraulic pressure P is introduced, a drain port 7, an output hydraulic port 8 that outputs an output hydraulic pressure P, and a human hydraulic pressure PL from a hydraulic source.
An input hydraulic pressure port 9 to which the hydraulic pressure P is input and an output hydraulic pressure return port 11 to which the output hydraulic pressure P is fed back via the orifice 10 are provided in sequence. The chamber 12 containing the second spring 3.5 is drained.

In the hydraulic control valve A having the above configuration, when the signal hydraulic pressure P input to the signal hydraulic port 6 gradually increases, the spool 2 is in the equilibrium position as shown in the upper half of FIG. 9 is held near the position where it is selectively opened and closed. On the other hand, the plunger 4 cannot move to the right because of the second spring 5. Therefore, the signal oil pressure P acts only on the left end of the spool 2, and the output oil pressure P is regulated as shown in the following equation. The outer diameter of the left end of the spool 2 is Dl, the outer diameter of the plunger 4 is D, the outer diameter of the right end of the spool 2 is F1, the spring load of the first spring 3 is Fl, and the outer diameter of the second spring 5 is D. Let the spring load be F2.

4 (D1 low-fh") π (D, "-03") π 4 When the signal oil pressure P further increases, the plunger 4 moves to the second position.
It moves against the spring 5 and comes into contact with the spool 2 as shown in the lower half of FIG. Therefore, the signal oil pressure P acts on the left end of the spool 2 and the plunger 4, and the output oil pressure P is regulated as shown in the following equation.

(D+"D3")π 4 FIG. 2 is a characteristic diagram showing the relationship between the signal oil pressure P and the output oil pressure P. As is clear from the figure, until the signal oil pressure P reaches the predetermined value P+ (P+ = 4 Fz /Dz"π), the rising slope of the output oil pressure P is small as shown in equation (1). Therefore, the output oil pressure P can be controlled with high precision.On the other hand, if the signal oil pressure P1 exceeds the predetermined value P1, (
As shown in equation 2), the rising gradient of the output oil pressure P becomes large, and it is possible to rapidly increase the output oil pressure P.

FIG. 3 shows an example in which the hydraulic control valve A is used for hydraulic control of the driven pulley of a belt type continuously variable transmission. In the figure, the belt-type continuously variable transmission 20 has an endless belt 23 wound between the driving pulley 21 and the driven pulley 22, and the driving side boot IJ 21 and the driven pulley 22 each have a V Oil chambers 24 and 25 are provided to make the shape of the groove variable. An output hydraulic port 8 of a hydraulic control valve A is connected to the oil chamber 25 of the driven pulley 22, and a solenoid valve 26 is connected to the signal hydraulic port 6. Further, the oil pump 27 discharges the hydraulic oil sucked from the oil reservoir 28 to the regulator valve 29, and the regulator valve 29 regulates the discharge pressure to the line pressure PL, and connects the hydraulic pressure port 9 of the hydraulic control valve A and the solenoid valve 26. is supplied to.

The electromagnetic valve 26 is duty-controlled by a control device (not shown), and can continuously change the signal oil pressure P1 according to the duty ratio. Therefore, by controlling the duty ratio, it is possible to change the oil pressure P of the driven side boolean IJ22 with the characteristics shown in Figure 2. Accurate oil pressure control is possible in the normal operating range, and is useful during kickdown and coasting. When downshifting, the output oil pressure is suddenly increased, allowing for agile downshifts.

FIG. 4 shows a second embodiment of the hydraulic control valve, in which the same parts as in FIG. 1 are given the same reference numerals. In this embodiment, the plunger 4 is disposed outside the left end of the spool 2, and one end of the second spring 5, which biases the plunger 4 to the left, is supported by the stepped surface of the valve body 1. In addition, the output hydraulic pressure return port 11 is formed at the right end of the valve podium l.
The output oil pressure P is fed back through a communication hole 2a provided in the output oil pressure return port 1 and the spool 2.

In this embodiment as well, the output oil pressure P has a two-stage bending characteristic, similar to the first embodiment.

In the above embodiment, in order to eliminate the influence of the residual pressure of the signal oil pressure P, the first spring 3 was provided to bias the spool 2 to the left, but this spring 3 may be omitted.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, the signal hydraulic port is provided with a plunger that is movable relative to the spool by a certain distance and receives a portion of the signal hydraulic pressure, and the plunger is moved in a direction opposite to the signal hydraulic pressure. Since a biasing spring is provided, when the signal oil pressure is below a certain value, the rising slope of the output oil pressure with respect to the signal oil pressure is gentle, and when the signal oil pressure exceeds a certain value, the rising slope of the output oil pressure with respect to changes in the signal oil pressure becomes high. , the output oil pressure increases rapidly. In this way, the change in the output oil pressure with respect to the signal oil pressure is non-linear, and when this oil pressure control valve is applied to the oil pressure control of a belt-type continuously variable transmission, highly accurate oil pressure control is possible in the normal operating range. During kickdown or coastdown, the output oil pressure is suddenly increased, allowing for agile downshifts.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a first embodiment of the hydraulic control valve according to the present invention, Fig. 2 is a characteristic diagram of its output hydraulic pressure, and Fig. 3 is a diagram showing the above hydraulic control valve for hydraulic control of a belt-type continuously variable transmission. The applied circuit diagram, FIG. 4, is a sectional view of a second embodiment of the hydraulic control valve. 2... Spool, 4... Plunger, 5... Subring, 6... Signal hydraulic port, 7... Drain port, 8... Output hydraulic port, 9... Input hydraulic port, 11 ...Output hydraulic pressure return port. Applicant Daihatsu Motor Co., Ltd. Agent Patent Attorney Hidetaka Tsutsui Figure 1 Figure 4 Figure 3

Claims (1)

[Claims] An input hydraulic port into which input hydraulic pressure is input, a drain port, an output hydraulic port which is formed at an intermediate portion between the input hydraulic pressure port and the drain port and outputs output hydraulic pressure, and an output hydraulic port that outputs output hydraulic pressure; Hydraulic control that has a signal hydraulic pressure port into which a pushing signal hydraulic pressure is input, and an output hydraulic pressure return port to which output hydraulic pressure is returned to push the spool in a direction opposite to the signal hydraulic pressure, and controls the output hydraulic pressure according to the signal hydraulic pressure. The valve is characterized in that the signal hydraulic port is provided with a plunger that is movable relative to the spool by a certain distance and receives a portion of the signal hydraulic pressure, and a spring is provided that biases the plunger in a direction opposite to the signal hydraulic pressure. Hydraulic control valve.