JPH0718456B2 - Boost control valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a boost control valve for controlling hydraulic pressure supplied to an oil passage,
Particularly, it relates to a structure of a boost control valve suitable for controlling a clutch and a brake.

(B) Conventional technology Generally, in a hydraulic clutch, if the pressure of hydraulic oil rises sharply when connecting the hydraulic clutch, torque is rapidly transmitted from the drive side to the driven side, which causes an uncomfortable shock to the work vehicle. It causes a vibration and makes the operation feeling of the operator worse.

Therefore, conventionally, a plunger is slidably provided in a casing having a primary passage for supplying pressure oil and a secondary passage for discharging pressure oil to control the hydraulic pressure sent to a hydraulic clutch. The boost control valve is proposed in Japanese Utility Model Laid-Open No. 59-5429.

The step-up control valve has a plunger provided in the casing with a concentric cylinder portion, and a piston is installed on the cylinder portion so as to be slidable and urged by a spring toward the primary passage. Further, an orifice is formed toward the cylinder portion in the portion of the plunger facing the primary passage. Then, the pressure oil supplied from the primary side passage first moves the plunger against the urging force thereof, and at the same time inserts the pressure oil from the orifice into the cylinder portion. Then, the piston moves larger than the plunger against the urging force and comes into contact with the casing end. In this state, pressure oil is further supplied to the cylinder portion so that the oil pressure in the cylinder portion becomes the same as the oil pressure in the primary passage, and at that time, the plunger is directed to the primary passage by the urging force of the spring. The plunger is brought into close contact with the primary passage to close the passage. Therefore, when the pressure-increasing control valve is connected to an oil passage for supplying pressure oil to the hydraulic clutch, the pressure of the pressure oil is increased stepwisely and smoothly, so that the hydraulic clutch is gently connected. Has been done.

(C) Problems to be Solved by the Invention However, the above-described conventional boost control valve has the pressure receiving area facing the primary passage of the plunger and the pressure receiving area of the portion of the cylinder portion facing the primary passage. Since the plungers block the primary side passage and the hydraulic clutch is connected, the hydraulic oil in the cylinder portion is further increased by the pressure oil that is further sent to the cylinder portion in the same manner as the primary side passage. Then, the plunger closes the primary passage with a stronger force.
Therefore, unless the relief valve is installed in the primary passage, the boost control valve may be damaged. Also, when the supply of pressure oil from the primary passage is stopped and the hydraulic clutch is disengaged,
The pressure oil in the cylinder portion is discharged from the orifice similarly to the time of feeding. As a result, the pressure oil at the time of discharge is discharged little by little over time, and it takes a very long time for the boost control valve to return to its original state.Therefore, reconnect the hydraulic clutch within a short time after the hydraulic clutch is disconnected. In such a case, the pressure oil may be sent to the pressure-increasing control valve that has not completely returned, causing a malfunction, and the hydraulic clutch may not normally be connected properly.

(D) Means for Solving the Problem The present invention is intended to solve the above-mentioned problems, and for example, as shown in FIG.
, A piston 11 is slidably installed separately from the plunger 9, and a first spring 10 is installed between the plunger 9 and the piston 11 to urge them in a direction to separate them from each other. The second spring 15 is installed with a free length between the piston 11 and the piston 11 so as to be compressed when they approach each other. Furthermore, in the piston 11,
The pressure oil sent from the primary side port 5 is sent into the piston chamber 12 formed by the cylinder portion 7 (7a) and the piston 11 through the orifice 21a, and the pressure oil is discharged from the piston chamber 12. When this is done, a check valve 21 configured to open the orifice 21a is installed.

(E) Operation Based on the above-mentioned configuration, when the boost control valve 1 is connected to the oil passage to control the hydraulic pressure, the pressure oil supplied to the primary side port 5 is gradually increased to a pressure receiving surface of the plunger 9. 9a is pressed against the biasing force. Then, when the hydraulic pressure in the primary side port 5 is increased to a predetermined pressure, the plunger 9 moves and the primary side port 5 is communicated with the secondary side port 6, and the surplus flow of the pressure oil flows to the secondary side port 6. It is discharged toward. at the same time,
Pressure oil is fed into the piston chamber 12 via the orifice 21a, whereby the piston 11 is moved to the plunger 9 side. The movement of the piston causes the first spring to move.
10 is compressed, which pushes the plunger 9
The secondary port 5 is gradually strongly closed. Therefore, the oil pressure in the port 5, that is, the oil pressure of the oil passage connecting the boost control valve 1 is gradually increased (the oil pressure increasing function). Further, when the piston 11 approaches its stroke end, the second spring 15 begins to be compressed between the plunger 9 and the piston 11, so that the primary side port 5 applies the force of the spring 15 to the plunger 9. Is further rapidly and elastically closed with a stronger force. Therefore, the oil pressure in the oil passage connecting the primary side port 5, that is, the boost control valve 1 is rapidly increased (hydraulic pressure sudden increase function). Further, the force of the pressure oil from the primary side port 5 to the secondary side port 6 and the plunger 9
The force to close the valve balances at a predetermined position, whereby the plunger 9 continues the relief while remaining stationary. Therefore, the hydraulic pressure in the oil passage to which the boost control valve 1 is connected is maintained at a predetermined relief pressure (relief function).

On the other hand, when the hydraulic pressure to the primary side port 5 is lowered by switching the switching valve or the like, the plunger 9 is brought into contact with the port 5 by the urging force of the first spring 10, whereby the primary side port 5 Then, the secondary port 6 is shut off. Then, due to the residual pressure in the piston chamber 12, pressure oil is transferred to the primary side port 5
At this time, the orifice 21a is released by the discharged oil, so that the pressure oil is quickly discharged and the piston 11 is returned to the original position (rapid drain function). Therefore, the boost control valve 1 can be quickly returned to the original state and ready for the next operation.

(F) Example Hereinafter, an example according to the present invention will be described with reference to the drawings.

As shown in FIG. 1 to FIG. 5, the boost control valve 1 discharges pressure oil and a primary side port 5 for supplying pressure oil to a valve body 3 provided with a plug 2 at one end thereof. The secondary port 6 is provided. A cylinder portion 7 is formed on the valve body 3 so as to communicate with the primary and secondary ports 5 and 6, and a collar 5a is formed at the boundary between the port 5 and the cylinder portion 7. Further, a plunger 9 is slidably fitted into the cylinder portion 7 and is urged by one end of a spring 10 toward the primary side port 5, and the plunger 9 communicates with a lower portion of its outer peripheral portion. A portion 9a is formed so that the front end side and the rear end side of the plunger 9 in the cylinder portion 7 are communicated with each other, and a taper portion 9b is formed at the front end portion so that the collar 5a of the primary side port 5 is oil-tight. It is configured to abut and block the port 5, and to shut off the primary port 5 and the secondary port 6. In addition, the cylinder portion 7
A sliding portion 7a having an inner diameter larger than that of the cylinder portion 7 is formed on the plug 2 side of the piston 1. The sliding portion 7a includes a piston 1 including a large diameter portion 11a, a small diameter portion 11b, and a protrusion portion 11c.
The large diameter part 11a is slidably and oil-tightly fitted in the installation. Further, the plunger 9 is concentrically formed with a sliding groove 9c and a communication oil passage 9d communicating with the primary side port 5, and the projection 9c of the piston 11 is formed in the sliding groove 9c.
Is slidably fitted. A piston chamber 12 is formed on the plug 2 side of the large-diameter portion 11a, and the side facing the plunger 9 abuts against a collar 13 formed at the boundary between the cylinder portion 7 and the sliding portion 7a of the valve body 3. hand,
The piston 11 is configured so as not to move beyond a predetermined position. Further, the other end of the spring 10 is in contact with the surface of the large diameter portion 11a facing the plunger 9, and urges the piston 11 away from the plunger 9. Further, a spring 15 is inserted into the protrusion 11c in a free length, and the spring 15 is a spring that is compressed by the piston 11 when the piston 11 is moved to the full stroke.
Along with 10, the plunger 9 is configured to be pressed toward the primary port 5.

On the other hand, the piston 11 is concentrically formed with the communication groove 16 and the sliding groove.
A collar 19 is provided at a portion of the sliding groove 17 facing the piston chamber 12, and a discharge oil passage 20 communicating from the sliding groove 17 to the cylinder portion 7 is formed. . Further, a check valve 21 having an orifice hole 21a formed at the tip thereof is slidably fitted in the sliding groove 17 by a spring 22. When the sliding groove 17 and the discharge-side oil passage 20 are contacted with each other in an oil-tight manner with respect to 19 and the pressure oil is discharged from the piston chamber 12, the piston chamber 12 resists the urging force of the spring 22. Away from the orifice hole
21a is released from the collar 19 and the piston chamber 12 and the drain oil passage 20
Are configured to communicate with each other.

The boost control valve 1 is connected to an oil passage 23 that supplies pressure oil with a hydraulic pump P, and a flow control valve 25 and a switching valve 26 are provided in the oil passage 23 from the upstream side. Actuator for hydraulic hydraulic clutch installed on the downstream side
27 is connected. Further, the discharge side oil passage 29 communicates with the secondary side port 6, and the surplus flow of the pressure oil pumped by the pump P along with the surplus flow discharged from the secondary side port 6 is directed to the tank 30. It is configured to flush.

Since the present embodiment is configured as described above, when the switching valve 27 is switched to connect the hydraulic clutch, the pressure oil supplied from the hydraulic pump P together with the hydraulic clutch actuator 27 causes the pressure control valve 1 Next port 5
Sent to. At this time, in the plunger 9, as shown in FIG. 1, the tapered portion 9b is brought into oil-tight contact with the collar 5a of the primary side port 5 by the urging force of the spring 10, and the piston 9
Since 11 is urged toward the plug 2 and is in contact with it, 1
The plunger 9 and the piston 11 do not move until the pressure oil in the secondary port 5 reaches a predetermined pressure. Then, as shown in FIG. 2, pressure oil is fed into the hydraulic clutch actuator 27, the piston of the actuator 27 is moved by a predetermined stroke, and the multiple plates of the hydraulic clutch are lightly contacted.
In this state, the oil pressure in the primary side port 5 is further increased, and the pressure oil is fed into the piston chamber 12 via the orifice 21a to increase the oil pressure in the piston chamber 12. The pressure P ₁ of the port 5 is equal to the cross-sectional area of the port 5.
A ₁ , the cross-sectional area of the sliding groove 9c of the plunger 9 is A _2, and the spring force of the spring 10 is K ₁ , When the value represented by is reached, the plunger 9 is separated from the collar 5a of the port 5 by the pressure P ₁ . Then, in the piston chamber 12, the primary side port 5
The pressure oil is sent from the orifice hole 21a of the check valve 21 through the communication oil passage 9d, the sliding groove 9c, the communication groove 16 and the sliding groove 17, but as shown in FIG. If the stroke of the piston 11 is ΔS and the spring constant of the spring 10 is R ₁ , the pressure P ₂ in the port 5 is Therefore, as the piston 11 moves toward the plunger 9, the pressure P ₂ in the primary side port 5 gradually changes with time t as shown in FIG. 6a. The pressure is increased, whereby the hydraulic clutch actuator 27 gradually and strongly presses the multiple plates of the hydraulic clutch to smoothly transmit the torque from the driving side to the driven side. When the piston 11 is further moved to reach its maximum stroke S, the spring 15 is pressed by the surface of the small diameter portion 11b of the piston 11 facing the plunger 9. As a result, the plunger 9 is pressed by the spring 15 in addition to the pressing force of the spring 10 pressed by the movement of the piston 11, so that the plunger 9 is elastically moved from P ₂ to P _MAX as shown in FIG. The pressure in the primary side port 5 is increased at a steep angle. Therefore, as shown in FIG. 4, the maximum stroke of the piston 11 is S, and the spring 15
If the spring force of the valve is K ₂ , the pressure P in the primary port 5
_MAX is This is the so-called relief pressure. In this state, the plunger 9
The pressure oil sent from the secondary port 6 to the secondary port 6 is suppressed by the taper portion 9b, and the spring 10, 1 to the plunger 9 is suppressed.
It is stopped at a position where the pressing force of 5 and the pressure P _MAX from the primary port 5 are balanced. Then, the pressure in the primary side port 5, that is, the pressure in the oil passage 23 is kept in the relief state by the relief pressure P _MAX , whereby the hydraulic clutch actuator 27 presses the multiple plates of the hydraulic clutch with a strong force. The clutch is changed from a so-called half-clutch state to a completely connected state.

On the other hand, as shown in FIG. 5, when the switching valve 26 is switched to disconnect the hydraulic clutch, the pressure oil supplied by the hydraulic pump P flows toward the tank 30 via the valve 26. At the same time, pressure oil is discharged from the actuator 27 and the hydraulic clutch is disconnected. At this time, the pressure in the primary port 5 is drastically dropped, the tapered portion 9b of the plunger 9 contacts the collar 5a, and the pressure in the piston chamber 12 is also dropped. 12
The pressure oil inside is discharged from the collar 19 portion toward the check valve 21. As a result, the check valve 21 is moved in the direction of releasing the orifice hole 21a against the biasing force of the spring 22, and the pressure oil in the piston chamber 12 is smoothly discharged from the orifice hole 21a through the discharge oil passage 20. Further, the discharged oil passes through the communication portion 9a of the plunger 9 and is discharged from the secondary port 6 toward the tank 30. Therefore, when the hydraulic clutch is disengaged, the boost control valve 1 immediately returns to the state before the operation and can cope with the next operation.

(G) Effect of the Invention As described above, according to the present invention, the valve body 3
A piston 11 is installed in the cylinder portion 7 (7a) of the piston 11 separately from the plunger 9, and the piston 11 and the piston 11 are spaced apart from each other and compressed when they are close to each other. Since the spring 10 and the second spring 15 are interposed, the primary side port 5
The first spring 10 is gradually compressed by the piston 11 which moves to the plunger 9 side in response to the introduction of the pressure oil from the piston 9, and the primary port 5 can be gradually closed by the plunger 9 (hydraulic pressure relaxation). Lifting function), then the second spring 15
By compressing the first spring 10, the plunger 9 that gradually closes the primary side port 5 can be pressed rapidly and elastically (hydraulic pressure sudden increase function). Therefore, with the movement of the piston 11 to the plunger 9 side, the hydraulic pressure in the oil passage connecting the boost control valve 1 is smoothly increased, and is rapidly increased at the stroke end of the piston 11. This can be performed easily and surely, and also when the hydraulic pressure is increased by the stroke end of the piston 11, the piston 11 is elastically and rapidly increased, thereby preventing an unpleasant shock when the hydraulic clutch is connected. In addition, the hydraulic pressure is applied to the plunger 9 from one side by the first pressure receiving surface 9b, and the hydraulic pressure and the spring biasing force by the second pressure receiving surface are applied in the other direction, and the area of the first pressure receiving surface is Has a large area of the second pressure receiving surface (A ₁ >
A ₂ ), the plunger 9 is balanced by the forces acting in both directions, and the excessive hydraulic pressure of the primary side port 5 is reduced to 2
It can be released to the secondary port 6 (relief function), whereby the plunger 9 can be used as a relief valve by resting in a predetermined position without completely closing the primary port 5, and thus boosting control. When controlling the pressure oil sent into the hydraulic clutch using the valve 1, the relief valve does not have to be provided in the oil passage. Further, pressure oil sent from the primary side port 5 to the piston 11 is supplied to the piston 11 to the piston chamber 12 formed by the cylinder portion 7 (7a) and the piston 21.
Since the check valve 21 is arranged so that the orifice 21a is opened when the pressure oil is discharged from the piston chamber 12 via the a, the pressure oil is sent to the piston chamber 12. At that time, the oil pressure is changed by the orifice 21a and is gradually sent into the piston chamber 12, thereby gradually reducing the pressure oil in the primary side port 5 and reducing the oil pressure in the port 5. The pressure oil can be slowly raised without suddenly rising, but when the pressure oil is discharged from the piston chamber 12, the pressure oil can be quickly discharged as the orifice 21a is released. It is possible (rapid drain function), so that the boost control valve 1 can be quickly returned from its operating state to its original state, and can be prepared for the next operation. Therefore, like a hydraulic clutch for forward / reverse traveling in a combine, etc. Multiple clubs Ji is the apparatus having to be constantly switching operation, can be extremely effective use of the boost control valve 1.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a boost control valve according to the present invention, FIG. 2 is a cross-sectional view showing an initial operation in which the plunger starts to move, and FIG. 3 is a cross-sectional view showing a pressure oil feeding state into a piston chamber. FIG. 4 is a sectional view showing a relief state by a plunger, FIG. 5 is a sectional view showing a discharge state of pressure oil from a piston chamber, and FIG. 6 is a diagram showing a pressure change at each operation thereof. 1 ... Boost control valve, 3 ... Valve body, 5 ... Primary port, 6 ... Secondary port, 7 ... Cylinder part, 7a ...
… Sliding part, 9 …… Plunger, 10 …… First spring, 11 …… Piston, 12 …… Piston chamber, 15 …… Second spring, 21 …… Check valve, 21a …… Orifice (Orifice hole ).

Claims (1)

[Claims] 1. A valve body is provided with a primary side port for feeding pressure oil, a secondary side port for discharging pressure oil, and a cylinder portion communicating with these ports, and the cylinder portion is provided with the primary side. And a step-up control valve in which a plunger that shuts off the secondary port is slidably installed, in which a piston is separated from the plunger and slidably installed in the cylinder portion, and
The first pressure receiving surface facing the next port and the pressure receiving surface of the piston are arranged so that the plunger and the piston act in a direction in which they approach each other, and a first spring is provided between the plunger and the piston. A second spring is installed between the plunger and the piston so as to be compressed when the plunger and the piston come close to each other. A check configured such that the pressure oil sent from the primary side port is fed into the piston chamber formed by and through the orifice and the orifice is released when the pressure oil is discharged from the piston chamber. A valve is installed, and the plunger is provided with a second pressure receiving surface which acts in a direction opposite to the first pressure receiving surface and has an area smaller than the area of the first pressure receiving surface. , The piston moves based on the oil pressure of the piston chamber introduced through the orifice, compresses the first spring, and the second spring after the piston abuts the second spring. Booster control valve configured to compress the spring of.