JPS6212672Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is a pressure regulating valve device for setting the working oil pressure for a hydraulic clutch in a hydraulic clutch type transmission installed in a self-propelled agricultural vehicle, a construction vehicle, etc. A control piston that receives the tip of the hydraulic pressure setting spring and increases the strength of the oil pressure setting spring by advancing the control piston is provided in the valve case so as to be able to move forward to a regulated position;
The present invention relates to a pressure regulating valve device that is provided with a throttle oil passage that is connected to an oil supply circuit for the hydraulic clutch and that is always open behind the control piston.

The pressure regulating valve device configured as described above is known from, for example, Japanese Utility Model Application No. 52-98051, etc., and the switching valve for switching and controlling the supply and discharge of hydraulic oil to and from the hydraulic clutch in a hydraulic clutch type transmission is moved to a neutral position. When the control piston is displaced from one working position or from one working position to another working position, the control piston is gradually advanced by the hydraulic action of the oil supply circuit via the throttle oil passage described above, and the control piston is moved forward for pressure setting. Since the strength of the spring is gradually increased, the hydraulic pressure applied to the hydraulic clutch is gradually increased to smoothly engage the hydraulic clutch and smoothly start or change the vehicle speed.

In a hydraulic pressure increasing type pressure regulating valve device in which the hydraulic pressure for clutch operation is gradually increased, in order to prevent a shock by allowing the hydraulic pressure to increase slowly until the hydraulic pressure at which engagement of the hydraulic clutch is completed, and then to increase the hydraulic pressure relatively quickly to a steady pressure to quickly achieve a stable vehicle running condition, conventionally, a conical spring as disclosed in Japanese Patent Publication No. 48-15809 or a multiple coil spring as disclosed in Japanese Utility Model Publication No. 55-10707 have been used as a valve spring for setting the hydraulic pressure, and the valve spring force is gradually increased within a small range during the initial period of the hydraulic pressure increase process and then significantly increased at the end of the hydraulic pressure increase process, thereby obtaining the above-mentioned two-stage hydraulic pressure increase characteristic.

However, the amount of oil passing through the throttle oil passage provided in the hydraulic pressure gradually increasing type pressure regulating valve device changes when the oil temperature is low and the oil viscosity is high, and when the engine rotation speed is low and the hydraulic pump rotation speed is low. It is a fact that when the amount of pump discharged oil is small, it decreases significantly, and as mentioned above, according to the conventional technology that attempts to obtain a quick rise of the clutch action oil pressure at the end of the oil pressure rise process by arranging the valve spring, When the oil temperature is low or the engine speed is low, the oil pressure rise at the end of the oil pressure rise process is greatly delayed due to the flow restriction by the throttle oil passage, and the clutch action oil pressure is quickly raised as expected and the vehicle is activated. The effect of quickly achieving stable running conditions was not achieved.

In view of this, this invention aims to achieve a rapid rise in oil pressure at the end of the rising process of the clutch action oil pressure by significantly increasing the amount of oil supplied behind the control piston in the pressure regulating valve device, rather than by arranging the valve spring as in the past. By adopting a structure that achieves rapid forward movement, stable vehicle running conditions can be quickly achieved without slowing down to reach steady pressure even when the oil temperature is low or the engine speed is low. It is an object of the present invention to provide a new pressure regulating valve device for a hydraulic clutch type transmission.

Regarding the illustrated embodiment, the configuration of the pressure regulating valve device according to the invention will be explained. In FIG. 1, 1 is:
It is a power shift shaft on which a plurality of idle speed change gears (not shown in the figure) (four in the case shown) are mounted in a hydraulic clutch type transmission that performs three speeds in the forward direction of the vehicle and one speed in the reverse direction of the vehicle. , on this power shift shaft 1 are four hydraulic clutches for selectively coupling each of the above-mentioned idle speed change gears to the power shift shaft 1, namely F ₁ hydraulic clutches 2F ₁ , F _{2 .}
Hydraulic clutch 2F ₂ , F ₃ Hydraulic clutch 2F ₃ and R
A hydraulic clutch 2R is provided. In order to supply hydraulic oil from the oil tank 3 to these hydraulic clutches _2F1-2R , a hydraulic pump 5 is inserted into the oil supply circuit 4 led from the oil tank 3 toward the hydraulic clutches _2F1-2R . In order to switch and control the supply and discharge of hydraulic oil to and from the hydraulic clutches _2F1-2R , the two ports on the primary side are connected to the oil supply circuit 4 and the oil tank 3, and the four ports on the secondary side are connected to the hydraulic clutch 2F. ₁ - 2R are provided with switching valves 6 connected to each other. The switching valve 6 discharges the hydraulic fluid from the full hydraulic clutch 2F ₁ -2R and moves it to a neutral position N where it disengages the full hydraulic clutch 2F ₁ -2R and to a corresponding one of the hydraulic clutches 2F ₁ , 2F ₂ , 2F ₃ or 2R. Forward first speed position F ₁ , in which hydraulic oil is supplied to the other three hydraulic clutches, and hydraulic oil is discharged from the other three hydraulic clutches, and only the one hydraulic clutch 2F ₁ , 2F ₂ , 2F ₃ or 2R is selectively engaged. 2
Speed position F ₂ , forward 3rd speed position F ₃ , reverse 1st speed position R
It is equipped with.

When the above-mentioned switching valve 6 is placed in each operating position F ₁ , F ₂ .F ₃ or R, each hydraulic clutch 2F ₁ , 2
In order to set the hydraulic pressure acting on F ₂ , 2F ₃ or 2R, a pressure regulating valve arrangement according to the invention is provided. This pressure regulating valve device is provided with a valve body 8 which is slidably inserted into a valve case 9 and which is biased to move in the backward direction by a hydraulic pressure setting spring 7 as usual. Pump port 10 and relief port 1 of valve case 9
an annular groove 12 for selectively communicating with 1;
A hole 14 is formed to allow the pump port 10 to communicate with the oil chamber 13 at the rear of the valve body 8 at all times. The pump port 10 is connected to the oil supply circuit 4 described above via a connection circuit 15, and the valve body 8 is connected to the oil supply circuit 4 that acts on the oil chamber 13.
The pump is moved forward as shown in the figure against the force of the spring 7 by the hydraulic pressure of the pump, and the pump port 10 and the relief port 11 are communicated through the annular groove 12 to perform a relief operation.

The tip of the oil pressure setting spring 7 is received by a control piston 17 provided in the valve case 9 so as to be able to move forward from the most retracted position shown by the chain line to the position where it abuts the retaining ring 16. This control piston 1
7. Behind the valve case 9, there is an oil chamber 18.
The oil chamber 18 is always connected to the oil supply circuit 4 via the connection circuit 15, an oil passage 19 in the valve case 9, and a throttle oil passage 20. The control piston 17 has a throttle oil passage 20 which is always open behind the piston 17 when the switching valve 6 is switched to any operating position F ₁ , F ₂ , F ₃ or R. The oil pressure of the oil supply circuit 4 is gradually applied to the rear of the piston 17 through the piston 17 to gradually advance the piston 17, thereby gradually increasing the strength of the oil pressure setting spring 7.

As described above, in particular, another throttle oil passage 21 is formed in the valve case 9 in parallel with the throttle oil passage 20 described above, and this other throttle oil passage 2
1 is also connected to the oil supply circuit 4 via the connection circuit 15 and the oil passage 19. The other throttle oil passage 21 is opened into the valve case 9 through a narrow annular groove 21a.
1a is blocked by the circumferential surface of the control piston 17 when the control piston 17 is in the most retracted state shown by the chain line, and opens behind the control piston 17 when the control piston 17 moves forward by more than a certain amount α as shown by the solid line. It is arranged and provided in the position.

In the illustrated case, an oil drain passage 22 that opens into the oil chamber 18 is formed in the valve case 9, and a valve seat 23 formed in the middle of this oil drain passage 22 is seated from the opposite side of the oil chamber 18 to drain the oil. A valve body 24 capable of blocking the oil passage 22 is provided, and a spring 25 for moving and biasing the valve body 24 in the opposite direction from seating on the valve seat 23 is connected to the stepped portion 9a in the valve case 9 and the valve body 24.
Both ends are received by the stepped portion 24a of the holder. An oil chamber 26 is provided in the valve case 9 behind the valve body 24, and the back surface of the valve body 24, that is, the surface opposite to the oil chamber 18, is moved in the direction in which the valve body 24 is seated on the valve seat 23. The oil passage 1 is formed in the pressure receiving part 24b that applies hydraulic pressure for moving and energizing.
9 is provided with an extension portion 19a that opens into the oil chamber 26,
The oil pressure of the oil supply circuit 4 is applied to the pressure receiving portion 24b. The pressure receiving area S ₁ of the pressure receiving part 24b is
It is larger than the pressure receiving area _S2 on the oil chamber 18 side behind the control piston 17 in the oil supply circuit 4.
Let P be the oil pressure of the spring 25, and F be the force that forces the spring 25 to retract the valve body 24.The pressure receiving areas S1, _S2 and the springs should be adjusted so that the following relationship holds: _S1 ×P> _S2 ×P+F ( ₁ ) The relationship with force F is set.

Since the pressure regulating valve device according to this invention is configured as explained above, when the switching valve 6 is switched and displaced to any of the operating positions F ₁ , F ₂ , F ₃ or R At that time, as shown in the figure, the strength of the spring 7, which urges the valve body 8, which is moved forward and performs a relief operation, in the backward direction and sets the clutch action oil pressure, is determined by the strength of the control piston 17 that receives the tip of the spring 7. , the hydraulic oil in the oil supply circuit 4 first gradually flows into the oil chamber 18 through the throttle oil passage 20 and is gradually advanced, thereby gradually increasing the oil pressure P in the oil supply circuit 4 and, therefore, the clutch. The working oil pressure P is gradually increased as shown by the relationship line _C1 shown in FIG. 2 with respect to the elapsed time t after the switching displacement of the switching valve 6. After the time _t1 when the control piston 17 is advanced by the amount α and the other throttle oil passage 21 is also opened behind the piston 17, the hydraulic oil in the oil supply circuit 4 is transferred to both throttle oil passages 20, 21 and behind the control piston 17, the piston 17 advances at a higher speed and the oil pressure setting spring 7
is increased at a higher rate, the clutch action oil pressure P is increased more rapidly, as shown in the relationship line _C2 in FIG.
The constant pressure P ₂ corresponding to the strength of the spring 7 at the most advanced position of the piston 17 in contact with the piston 6 is reached relatively quickly. Each hydraulic clutch 2F ₁ , 2F ₂ , 2
The engagement of F ₃ or 2R is completed at a relatively low hydraulic pressure, and the hydraulic pressure at the time t ₁ above is
Already completed in P ₁ .

Note that the valve body 24 selectively blocking the oil drain passage 22 described above faces the valve seat 23 during the rise of oil pressure and in the clutch engaging state shown in FIG. When the switching valve 6 is returned to the neutral position N and switched between the two working positions, the oil supply circuit 4 is temporarily moved to the oil tank 3.
When the oil pressure is removed from the oil chamber 26 behind the valve body 24, the force of the spring 25 causes the spring 25 to quickly move backward, leaving the valve seat 23 and opening the oil drain passage 22. The block is released to quickly drain oil from the oil chamber 18, and the control piston 17 is moved backward.

As is clear from the above explanation, this invention aims to achieve smooth engagement of the hydraulic latch and to smoothly start the vehicle or change the vehicle speed. Another throttle oil passage 21 connected to the oil supply circuit 4 for the pressure regulating valve device is blocked by the circumferential surface of the control piston 17 when the control piston 17 of the pressure regulating valve device is in its most retracted state, so that the control piston 17 cannot move forward by more than a certain amount. Then, another throttle oil passage 21 that opens behind the control piston 17 is provided, and the other throttle oil passage 21 described above supplies oil to the rear of the control piston 17 from the middle of the rising process of the clutch action oil pressure. By significantly increasing the amount, the control piston 17 is moved forward quickly, and the strength of the oil pressure setting spring 7 is relatively quickly increased, and the clutch action oil pressure is relatively quickly built up, allowing stable vehicle running. Get the status quickly.

In this way, in addition to the conventional throttle oil passage 20, another throttle oil passage 2 is used to ensure a rapid rise in oil pressure at the end of the clutch action oil pressure rise process.
According to the present invention, which is obtained by significantly increasing the amount of oil supplied by supplying oil to the rear of the control piston 17 through the control piston 1, the conventional device that was provided with only a throttle oil passage corresponding to the former throttle oil passage 20 can be improved. In contrast, when the oil temperature is low and the oil viscosity is high, or when the engine speed is low and the pump discharge amount is small, the influence of flow restriction by the throttle oil passage is alleviated, and it takes less time for the clutch working oil pressure to reach steady pressure. Without any delay, a stable vehicle running condition as expected can be quickly achieved. In particular, the other restricting oil passage 21 mentioned above is provided so as to be involved in supplying oil to the back of the control piston only after the engagement of the clutch is completed. The restriction level may be smaller than that of the throttle oil passage 20 that allows the oil viscosity to perform shock-free operation. By employing as the other throttle oil passage 21 a throttle oil passage with a small degree of restriction that does not significantly increase the degree of flow restriction even if it becomes large,
The effect of quickly reaching steady pressure even when the oil temperature is low can be further enhanced.

According to this invention, in a steady state when the hydraulic clutch is engaged, the control piston 1
Since the rear of the control piston 17 is in communication with the clutch oil supply circuit 4 via the two throttle oil passages 20 and 21, the amount of oil behind the control piston 17 prevents oil leakage from the piston 17 in the normal state. It is always ensured to be negligible, and there is no inconvenience such as when the clutch working oil pressure once drops below the steady pressure due to such oil leak, and it also has the advantage of reliably maintaining the steady pressure.

[Brief explanation of the drawing]

FIG. 1 is a schematic vertical sectional view of an embodiment of the present invention shown together with a hydraulic circuit, and FIG. 2 is a schematic graph showing the operation of the embodiment. 1...Power shift shaft, 2F ₁ , 2F ₂ , 2F ₃ ,
2R...Hydraulic clutch, 4...Oil supply circuit, 7...
Oil pressure setting spring, 8... Valve body, 9... Valve case, 16... Retaining ring, 17... Control piston, 18... Oil chamber, 19... Oil passage, 20... Throttle oil passage, 21... ...Other throttle oil passage, 21a...
Annular groove.

Claims (1)

[Scope of utility model registration request] This is a pressure regulating valve device for setting the working oil pressure for the hydraulic clutch in a hydraulic clutch type transmission, and has a control piston inside the valve case that receives the tip of the oil pressure setting spring and increases the strength of the oil pressure setting spring by advancing it. A pressure regulating valve device is provided with a throttle oil passage that is movable to advance to a regulated position and that is connected to an oil supply circuit for the hydraulic clutch and that is always open behind the control piston. and another throttle oil passage connected to the oil supply circuit,
A pressure regulating valve characterized in that another throttle oil passage is provided, which is blocked by the circumferential surface of the control piston when the control piston is in its most retracted state, and opens behind the control piston when the control piston moves forward by a certain amount or more. Device.