JPH04254002A - Working pressure control circuit of fluid pressure actuator - Google Patents

Abstract

PURPOSE:To prevent lag due to a throttle at the time of starting the supply of working pressure in a circuit having a working element of a fluid pressure actuator and throttle in a working pressure path connected to the element. CONSTITUTION:A switch-over valve 24 disposed in an oil path 21 having a throttle 22 is switched, taking the pressure downstream from the throttle as switching pressure. The valve 24 supplies oil pressure as the working pressure for an element 11, by-passing the throttle 212 until the switching pressure reaches preset value. After the pressure reaches the preset value, a connected oil path is closed, and hereinafter the working pressure is given through the throttle 22 while being regulated by the throttle.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operating pressure control circuit for fluid pressure operated equipment such as a control hydraulic circuit for an automatic transmission.

0002

2. Description of the Related Art Some shift control hydraulic circuits for automatic transmissions, which serve as operating pressure control circuits for fluid pressure operated equipment, have a throttle in the operating pressure supply system. In the case of an automatic transmission, this means that the transmission train is equipped with various friction elements (clutches, brakes, etc.), and these elements are selectively operated hydraulically to select a predetermined gear and switch the friction elements to be operated. However, in order to automatically perform this shift, automatic transmissions are equipped with the following steps, as described in the "RE5RO1A Type Automatic Transmission Maintenance Manual" published by Nissan Motor Co., Ltd. It is equipped with a shift control hydraulic circuit consisting of hydraulic oil passages for each friction element, actuators, accumulators, shift valves, etc. For the selective hydraulic operation of various friction elements, this hydraulic circuit supplies hydraulic pressure to the hydraulic oil passages of the corresponding friction elements to hydraulically operate the friction elements, thereby selecting a predetermined gear in the automatic transmission. let In such an operating pressure system, a throttle 1 is generally set in the circuit as shown in FIG. 4 in order to gradually release the supply pressure to friction elements such as clutches and improve shift shock.

[0003] In the illustrated example, a one-way orifice is configured by a throttle 1 and a check valve 2, and the operating pressure (forward clutch (FWD/C), high clutch (H/C), reverse clutch ( Rev/C) is supplied, and the friction element (clutch) is hydraulically operated.

0004

[Problem to be Solved by the Invention] However, in a working pressure system having a restriction as described above, when the input is uniformly restricted from the initial stage of supplying the main pressure, this may cause a lag in the operation of the working element. There is. That is, in the configuration shown in FIG. 4, since the engagement of the clutch is simply throttled, as shown in FIG.
The clutch piston is stroked from t0 at the start of the supply of v/C (use pressure) until time t1 when pressure A is reached, but during this period (period Δt) the clutch is ON.
do not. Therefore, it takes that much time to turn on, and this causes a lag.

An object of the present invention is to improve a working pressure system having a restriction in a working pressure path connected to a working element of a working device,
It is an object of the present invention to provide an operating pressure control circuit that can suppress the above-mentioned lag and can easily realize this.

[0006]

[Means for Solving the Problems] To this end, the present invention provides a working pressure system having a restriction in the working pressure path connected to the working element of a hydraulically operated device, in which a valve can be switched at the pressure downstream of the restriction. and the first one while the pressure is lower than the set value.
In the state, the operating pressure path of the valve communicates with the pressure path before and after the throttle, and in the second state, which is greater than the set value, a switching valve is provided that switches to close the operating pressure furnace of the valve. be.

[0007]

[Operation] The operating pressure system supplies operating pressure through the restriction of the operating pressure path connected to the operating element of the fluid pressure operated device to operate the element. By the way, the throttle is provided with a switching valve that can be switched by the pressure downstream of the throttle, and this switching valve is
In the first state, when the pressure is lower than the set value, the operating pressure path of the switching valve communicates the pressure path before and after the throttle, and in the second state, where the pressure is higher than the set value, the operating pressure path of the switching valve is closed. Change. Therefore, in the first state, the operating pressure can be supplied to the actuating element by bypassing the restriction, and even if a predetermined restriction is set, the lag caused by the restriction at the initial stage of supply will suppress this. Can be done.

[0008]

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows the configuration of a working pressure control circuit according to an embodiment of the present invention, which is applied to a shift control hydraulic circuit for an automatic transmission described in the above-mentioned document, for example. As shown in the figure,
The oil passage 3 is provided with a one-way orifice consisting of a throttle 1 and a check valve 2, and the source pressure side oil passage (upstream) is supplied with, for example, reverse clutch pressure as the source pressure, and the oil pressure passes through the throttle 1 and is applied to the friction element ( reverse clutch).

[0009] In a circuit having a restriction in the friction element and the oil passage communicating therewith, a switching valve 4 is added as shown in the figure in order to prevent lag at the initial stage of supplying the source pressure. The switching valve 4 is a valve that is switched by the pressure after throttling (clutch pressure), and the oil passage of the valve communicates the oil passage before and after the throttling while the pressure is lower than the set pressure, and when the pressure is lower than the set pressure. The structure shall be such that it does not communicate when the voltage is high. In other words, the switching valve added as shown in the figure uses the clutch pressure as the switching pressure, and until the clutch pressure reaches a certain pressure (pressure resisting the spring), the throttle 1 is closed.
A switching valve 4 is added to the operating pressure system so as to communicate the clutch and close the communicated oil passage after the clutch pressure reaches a certain pressure.

Therefore, the switching valve 4 allows hydraulic pressure to be supplied by bypassing the throttle 1 until the clutch pressure reaches the switching pressure of the valve, and in this case, the switching valve 4 functions as an orifice bypass valve. Therefore, as shown in FIG. 2, when the supply of source pressure is started at time t0, while the clutch pressure is low, hydraulic pressure cannot be supplied to the clutch without going through the throttle as shown in FIGS. 4 and 5. Therefore, the lag (Δt) can be eliminated, and while the oil pressure rises quickly, the supply pressure can be controlled with an upward slope as shown in the figure (after t0 in FIG. 2).

Further, with reference to FIG. 3, a specific example including the configuration on the source pressure side and the configuration on the friction element side will be explained.

In the figure, reference numeral 11 denotes a band brake as a friction element for selecting second speed and fourth speed.
shall be operated (fastened) appropriately by the band servo 12. The band servo 12 is a known one, with built-in springs 13 and 14.
A stem 15 is elastically supported in the illustrated position by a spring force difference, and the band brake 11 is deactivated (released) in this stem position. The band servo 12 has three hydraulic chambers 16, 17, and 18, and when hydraulic pressure (second-speed servo apply pressure P) is supplied to the second-speed servo apply chamber 16, the stem 15 is advanced to engage the band brake 11. death,
In this state, when hydraulic pressure is also supplied to the 3rd speed servo release chamber 17, the band brake 11 is released by retracting the stem 15 depending on the size of the piston pressure receiving area, and in this state, the hydraulic pressure is also supplied to the 4th speed servo apply chamber 18. When supplying, the stem 15 is advanced and the band brake 11 is re-engaged.

The second speed servo apply chamber 16 is connected to an oil passage 21 via an oil passage 19. The oil passage 21 has a throttle 22 and a check valve 2.
The oil passage has a one-way orifice consisting of three orifices, and is provided with a switching valve 24 that assumes the position shown in the figure in a normal state (no pressure), as shown in the figure. The switching valve 24 includes a spool 25 and a spring 26 that biases the spool to the left in the figure.
The bypass passage of the throttle 22 has oil passages 27, 28,
29, the oil passage 27 is upstream of the throttle 22 (oil passage 21), and the oil passage 29 is downstream of the throttle 22 (oil passage 21).
Connect to each. The switching valve 24 is a valve having the function described in the explanation regarding FIGS. 1 and 2 above, and when supplying the apply pressure P described later, it bypasses the throttle 22 until it reaches its own switching pressure on the downstream side of the throttle. When the switching pressure is reached and the spool 25 is switched to the right side in the figure to the extent that it can cut the oil passage, the bypass is shut off.

The oil passage 21 having such a switching valve 24 and one-way orifice is connected to a shift valve 31 through an oil passage 30. The shift valve 31 is provided with a spool 32, which is elastically supported by a spring 33 at the position shown in the right half and stroked to the position shown in the left half by supplying pressure to a chamber 34. At the former spool position, the shift valve 31 connects the oil passage 30 to an oil passage 35 to which the forward travel range pressure PP is supplied, and at the latter spool position, it connects the oil passage 30 to the second oil passage 35.
It is assumed that it communicates with an oil passage 36 leading to a shift valve (not shown). An oil passage 37 to which a constant pilot pressure PP is supplied is connected to the chamber 34, and an orifice 38 is connected to this oil passage.
and a drain port 39. A shift solenoid 40 is provided to open and close the drain port 39, and when this solenoid is turned on, a plunger 51 is advanced by electromagnetic force to close the drain port 39 and supply a pilot pressure PP to the chamber 34.

The operation of the above example will now be explained. While the driver desires forward travel and sets the manual valve (not shown) to the forward travel (D) range, the forward travel range pressure PD continues to be supplied to the oil passage 35. On the other hand, in this D range, the first
When selecting the speed, turn on the shift solenoid 40.
The drain port 39 is closed and the pilot pressure PP is supplied to the chamber 34. Therefore, the shift valve 31 is connected to the spool 3.
2 is placed in the left half position in the figure, and the oil passage 30 is connected to the oil passage 36 from the second shift valve. However, in the first speed, the second shift valve communicates the oil passage 36 to the drain port, does not supply hydraulic pressure to the second speed servo apply chamber 16, and releases the band brake 11 to select the first speed. enable.

[0016] When a driving condition is reached in which the gear should be shifted to second gear, a computer (not shown) electronically determines this.
turns off the shift solenoid 40. This causes the shift solenoid 40 to open the drain port 39, leaving the downstream side of the orifice 38, that is, the chamber 34, in an unpressurized state. Therefore, the shift valve 31 moves the spool to the position shown in the right half, connects the oil passage 30 to the oil passage 35, and supplies the forward travel range pressure PD to the oil passage 30. As a result, hydraulic pressure is supplied to the 2nd speed servo apply chamber 16, and the band servo 12 engages the band brake 11 via the stem 15 due to the 2nd speed servo apply pressure P generated in the chamber 16. In this case, the switching valve 24 is connected to the throttle 22 in the path of the oil passages 27 to 29.
By supplying hydraulic pressure by bypassing the
, 5, the shift delay can be eliminated compared to that in the case of shifting. Moreover, after switching, the predetermined throttle 22 can be utilized, and as a result, the increase in oil pressure can be slowed down with the slope as illustrated in FIG.
It is possible to alleviate the shock of shifting from 1st to 2nd speed due to the engagement of 1, and it is also possible to allow the throttle 22 and the switching valve 24 to perform a large function.

In addition, hydraulic pressure is also supplied to the 3rd speed servo release chamber 17 of the band servo 12 in a circuit section not shown, the stem 15 is moved backward to release the band brake 11, and the high clutch (not shown) is also supplied with hydraulic pressure. When the automatic transmission is operated, the automatic transmission shifts from the second speed to the third speed, but if the technology according to the present invention is applied to a circuit having a throttle in the circuit portion for this purpose, the same speed change as described above can be achieved with respect to the shift. The working effect can be achieved.

[0018]

[Effects of the Invention] According to the present invention, by using a switching valve that can be switched by the pressure downstream of the throttle, it is possible to bypass the throttle and speed up the rise at the start of supply of working pressure, and after the bypass is shut off, the switching valve can be switched by the pressure downstream of the throttle. Since the operating pressure can be supplied using the throttle, a lag in the operation of the operating element can be suppressed, and the function of the throttle can be easily ensured.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an operating pressure control circuit according to an embodiment of the present invention.

FIG. 2 is a time chart for explaining the circuit.

FIG. 3 is a diagram showing an example of a configuration using a band brake as an example of a friction element of an automatic transmission.

FIG. 4 is a diagram showing a conventional general circuit configuration.

FIG. 5 is a diagram showing an operation time chart in the same figure.

[Explanation of symbols]

1 Aperture 2 Check valve 3 Oil road 4 Switching valve 5 Spring 11 Band brake 12 Band servo 13, 14 spring 15 Stem 16 2-speed servo apply chamber 17 3-speed servo release chamber 18 4-speed servo apply chamber 19, 21, 30 Oil road 22 Aperture 23 Check valve 24 Switching valve 25 Spool 26 Spring 27, 28, 29 Oil passage 31 Shift valve

Claims (1)

[Claims] Claim 1: In an operating pressure system having a restriction in an operating pressure path connected to an operating element of a fluid pressure operated device, a valve capable of switching at a pressure downstream of the restriction, the valve being operable while the pressure is lower than a set value. In the first state, the operating pressure path of the valve communicates with the pressure path before and after the throttle, and in the second state, which is greater than the set value, a switching valve is provided that switches to close the operating pressure path of the valve. An operating pressure control circuit for a fluid pressure operated device, characterized in that: