JPS6146291Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a direct acting relief valve used to control pressure within a hydraulic circuit.

FIGS. 1 and 2 show conventional direct-acting relief valves.

In the figure, 1 is a casing, in which a high-pressure side oil chamber 2 communicating with the pump discharge port is bored in the radial direction, and a low-pressure side oil chamber 3 communicating with the tank is bored in the axial direction. and the high pressure side oil chamber 2
A relief valve 4 is provided between the oil chamber 3 and the low pressure side oil chamber 3.

The relief valve 4 has a cylindrical sleeve 5 fixed to the casing 1, and the sleeve 5 has a valve chamber 6 bored in the axial direction with a predetermined hole diameter. It has a spring chamber 7 bored in a large diameter on one side. The sleeve 5 also has a radial oil hole 12 located on the other side of the valve chamber 6 to connect the high pressure side oil chamber 2 to the valve chamber 6, and a radial oil hole 12 to connect the valve chamber 6 to the low pressure side oil chamber 6. An oil hole 13 in the axial direction is bored to communicate with the oil hole 13 in the axial direction. A valve seat 11 having a predetermined hole diameter smaller than the valve chamber 6 is provided at the outflow end of the oil hole 13 in the axial direction. Therefore, the pressure oil flowing radially inward from the high pressure side oil chamber 2 toward the valve chamber 6 via the radial oil hole 12 flows from the valve chamber 6 to the axial oil hole 13.
It flows out in the axial direction toward the low-pressure side oil chamber 3 through.

Reference numeral 8 denotes a poppet valve body slidably inserted into the valve chamber 6, and one end of the poppet valve body 8 is connected to the spring chamber 7.
A spring 10 is provided between the spring receiver 9 extending inward and provided in the spring chamber 7 and the spring receiver portion 8A of the poppet valve body 8.
is installed. On the other hand, a conical valve portion 8A is formed on the other end side of the poppet valve body 8 so as to be able to sit on and off the valve seat 11, and is normally supported by a spring 10.
A is urged to sit on the valve seat 11.
Further, the poppet valve body 8 is provided with an oil passage 14 that communicates the low-pressure oil chamber 3 with the spring chamber 7, and a constricted portion 14A is formed in a portion of the oil passage 14. In the figure, 15 is a screw for adjusting the spring force of the spring 10, 16 is a lock nut, and 17, 1
8 and 19 each indicate a seal member.

The relief valve according to the prior art has the above-mentioned configuration, and the diameter d ₁ of the poppet valve body 8 is equal to the diameter d 1 of the poppet valve body 8.
It is larger than the diameter d ₂ of the contact portion with the valve seat 11 at B. Therefore, if the pressure inside the high-pressure side oil chamber 2 is P, then the poppet valve body 8 has π/4(d ₁ ² −
A force of d ₂ ² )×P is applied to the spring 10 to push it in the opposite direction. Therefore, when the pressure P in the high pressure side oil chamber 2 becomes larger than the set pressure due to the spring force of the spring 10, the poppet valve body 8 as shown in FIG.
is removed from the valve seat 11, and the high pressure side oil chamber 2 and the low pressure side oil chamber 3 communicate with each other, whereby the pressure oil in the high pressure side oil chamber 2 is relieved to the low pressure side oil chamber 3.

However, in the conventional relief valve as described above, when the poppet valve body 8 opens, the pressure oil in the high-pressure side oil chamber 2 becomes a high-speed jet and flows in the direction shown by the arrow in FIG. As a result, the pressure in the region a near the tip of the valve portion 8B of the poppet valve body 8 becomes lower than that in the low-pressure oil chamber 3 where the flow velocity is slower than in this region. As a result, the pressure inside the spring chamber 7 becomes equal to the pressure in the above-mentioned area a, and the low pressure side oil chamber 3
lower than the internal pressure. In this way, when the pressure in the spring chamber 7 no longer follows the pressure in the low pressure side oil chamber 3,
The relief valve 4 has a drawback that it is not possible to perform pressure control to make the differential pressure between the high pressure side oil chamber 2 and the low pressure side oil chamber 3 constant.

Further, since the spring chamber 7 is always in communication with the low pressure side oil chamber 3 via the oil pipe 14, the pressure inside the low pressure side oil chamber 3 and the spring chamber 7 are equal to each other. When the poppet valve body 8 opens in this state, the throttle part 14A is inserted into the oil pipe 14.
However, due to the action of the high-speed jet described above, the pressure in the area a is lower than that in the low-pressure side oil chamber 3, so the oil in the spring chamber 7 is quickly sucked out, and the oil in the spring chamber 7 is becomes a negative pressure state. As a result, the function of preventing oscillation of the poppet valve body 8 by the throttle portion 14A is lost, resulting in a drawback that the operation of the relief valve becomes unstable.

The present invention was developed in view of the shortcomings of the conventional technology, and is a direct-acting type that maintains the pressure in the spring chamber at approximately the same pressure as the pressure in the low-pressure side oil chamber, thereby achieving stable relief performance. The purpose is to provide a relief valve.

In order to achieve this objective, the present invention has a valve chamber bored in the axial direction with a predetermined hole diameter, a spring chamber formed on one side of the valve chamber, and a spring chamber formed on the other side of the valve chamber. An oil hole is formed in the radial and axial directions, through which pressure oil flows radially inward from the high-pressure side oil chamber and flows out in the axial direction toward the low-pressure side oil chamber, and an oil hole is formed at the axial outflow end of the oil hole. , a valve seat having a predetermined hole diameter smaller than the valve chamber, and a valve part slidably provided in the valve chamber, one end extending into the spring chamber, and the other end attaching to and detaching from the valve seat. A hole is drilled into the poppet valve body so as to communicate the worn out poppet valve body, a spring stretched in the spring chamber and biasing the poppet valve body toward the valve seat, and the spring chamber and the low pressure side oil chamber. In the direct-acting type relief valve, the poppet valve body has a non-streamlined deflector located in the axial oil hole protruding from the valve portion tip of the poppet valve body. The oil passage is characterized in that the oil passage is opened at an end face of the deflector on the low pressure oil chamber side.

With this configuration, the flow direction of the jet flowing out from the valve seat into the oil hole in the axial direction is changed by the deflector, and a stagnation part is created near the opening of the oil pipe, and the stagnation part is The pressure is maintained at approximately the same pressure as the pressure in the low pressure side oil chamber. As a result, the pressure in the spring chamber, which is communicated via the oil pipe, becomes approximately the same pressure as that in the low-pressure side oil chamber, making stable pressure control possible and preventing oil from being sucked out from the spring chamber. .

Hereinafter, an embodiment of the present invention will be described based on FIG.

In this figure, the same components as those in FIG. A deflector 22 is provided to protrude in the radial direction, and a constricted portion 14A of the oil passage 14 communicating with the spring chamber 7 is opened at the end face on the low pressure side oil chamber 3 side. The oil hole 23 that communicates the low pressure side oil chamber 3 and the valve chamber 6 is formed in a stepped shape. That is, on the valve chamber 6 side of the oil hole 23, the portion where the valve seat 11 is formed is defined as a small diameter portion 23A, and the portion from the vicinity of the protruding position of the deflector 22 of the poppet valve body 8 to the low pressure side oil chamber 3 side The diameter of the portion is enlarged to form a large diameter portion 23B.

The direct-acting relief valve according to the present invention has the above-described configuration, and its relief function is not particularly different from that of the prior art described above. When the relief valve 21 is opened, when the poppet valve body 8 is separated from the valve seat 11, the pressure oil in the high-pressure oil chamber 2 flows between the area around the poppet valve body 8 and the portion forming the valve seat 11. The oil flows into the oil hole 23 as a jet from the annular passage formed therebetween. However, as shown by the arrow in FIG.
The direction of the flow can be changed by a deflector 22 protruding from the tip. Since the oil hole 23 is enlarged in diameter to form a large-diameter portion 23B around the position where the deflector 22 is formed, the flow velocity after passing through the deflector 22 is significantly reduced. Moreover, as described above, since the direction of the jet flow is changed by the deflector 22, a vortex is formed in the area A near the opening to the oil hole 23 of the oil passage 14 bored in the poppet valve body 8, as shown in FIG. The area A becomes a stagnation area, and the flow rate decreases extremely. As a result, the pressure in the above-mentioned area A does not decrease and is maintained at approximately the same pressure as the pressure in the low pressure side oil chamber 3.
For this reason, the pressure inside the spring chamber 11 is reduced to the low pressure side oil chamber 3.
The pressure of the relief valve 21 can be controlled based on the pressure difference between the high-pressure oil chamber 2 and the low-pressure oil chamber 3.

Further, since the pressure within the spring chamber 7 is approximately equal to the pressure in the region A, the oil fluid is not sucked out from the spring chamber 7 and the pressure does not become negative, as in the case of the prior art described above. When the volume of oil that enters the spring chamber 7 of the poppet valve body 8 flows out from the oil pipe 14, the throttling effect of the throttle portion 14A is fully exerted, and the damping effect is ensured. , the poppet valve body 8 does not vibrate, and the stability of the relief valve is not impaired. Furthermore, since the resistance of the deflector acts in a direction that cancels out the fluid force acting on the valve, good relief characteristics can be obtained.

Note that the deflector 22 for preventing a pressure drop is not limited to a brim shape, but may be a conical shape or other shape, as long as it has a non-streamline shape.

As described in detail above, according to the direct-acting relief valve of the present invention, a non-streamlined deflector is provided protruding from the tip of the poppet valve body, so that the low pressure of the oil passage bored in the poppet valve body is reduced. The pressure near the opening toward the side oil chamber does not decrease, and the pressure in the spring chamber 7 can always follow the pressure in the low-pressure side oil chamber. Therefore, the relief valve can perform the function of keeping the differential pressure between the high-pressure oil chamber and the low-pressure oil chamber constant, and the stability of its operation can be significantly improved.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view of a direct-acting relief valve according to the prior art, Fig. 2 is an enlarged view of the main part of Fig. 1, and Fig. 3 is an enlarged longitudinal cross-sectional view of the main part of a direct-acting relief valve according to the present invention. It is. 2...High pressure side oil chamber, 3...Low pressure side oil chamber, 6...
Valve chamber, 8...Poppet valve body, 11...Valve seat, 21
... Relief valve, 22 ... Deflector, 23 ...
Oil hole, 23A...Small diameter part, 23B...Large diameter part.

Claims (1)

[Claims for Utility Model Registration] (1) A valve chamber bored in the axial direction with a predetermined hole diameter, a spring chamber formed on one side of the valve chamber, and a spring chamber formed on the other side of the valve chamber. an oil hole formed in the radial direction and the axial direction, through which pressure oil flowing radially inward from the high pressure side oil chamber flows out in the axial direction toward the low pressure side oil chamber, and an oil hole formed at the axial outflow end of the oil hole, a valve seat having a predetermined hole diameter smaller than the valve chamber; and a valve portion that is slidably provided in the valve chamber, one end extending into the spring chamber, and the other end attaching to and detaching from the valve seat. a poppet valve body, a spring stretched in the spring chamber and biasing the poppet valve body toward the valve seat, and a hole formed in the poppet valve body so as to communicate the spring chamber and a low pressure side oil chamber. In the direct-acting type relief valve, the valve body includes a non-streamlined deflector protruding from the tip of the valve portion of the poppet valve body and located within the oil hole in the axial direction. . A direct-acting relief valve, characterized in that the oil passage is opened at an end face of the deflector on the low-pressure oil chamber side. (2) An axial oil hole communicating between the valve chamber and the low-pressure side oil chamber is formed in a stepped shape, and the hole diameter of the axial oil hole in the vicinity of the deflector is set to be the same as that of the hole in the valve seat portion. A direct-acting relief valve according to claim (1) of the utility model registration, which is formed to be larger than the diameter.