JP3310170B2 - Relief valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a relief valve of the balance piston type mainly used for a hydraulic drive device using tap water or fresh water as a working fluid.

[0002]

2. Description of the Related Art Hitherto, as a drive source for driving a high-speed and large-power actuator, a hydraulic drive device mainly using mineral oil as a working fluid has been used. However, the disadvantages of the hydraulic drive device in which the working fluid is mineral oil include a risk of fire due to burning of the mineral oil, a risk of environmental pollution caused by leakage of the mineral oil, and a problem of the working fluid being used. There are problems such as the necessity of disposal of mineral oil waste liquid at the time of replacement. In particular, it is clear that there is a great danger in spreading the fire, and there is a demand for a hydraulic drive device using water as a working fluid. To develop this hydraulic drive, it is essential to set the maximum pressure of the hydraulic circuit and to develop a hydraulic relief valve that keeps the circuit pressure constant.

[0003]

When water is used as a working fluid for a balance piston type relief valve, there is a problem of cavitation. Cavitation means that when the pressure difference before and after the throttle is large, a pressure drop occurs according to the flow velocity of the fluid passing through the throttle, and on the low pressure side, the pressure may be lower than the saturated steam pressure of the fluid. Is a phenomenon in which bubbles (cavities) are generated in the air. When the cavitation is generated, not only noise is generated but also a strong impact force is generated, and damage (cavitation erosion) is caused to a liquid contact portion in contact with the working fluid. When using water or a liquid with low viscosity like water as the working fluid, cavitation is likely to occur because the saturated vapor pressure is higher than that of oil, and water or a liquid with low viscosity like water is used as the working fluid. In the relief valve described above, there is a problem that the main valve and the valve seat of the main valve portion and the liquid contact portion of the poppet valve and the valve seat of the pilot portion which are liable to cavitation are damaged, and the life of the relief valve is shortened. Was.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has been made in consideration of the above problems, and has been made in consideration of the above circumstances. It is an object of the present invention to provide a relief valve in which a liquid part is made of a ceramic or a super alloy and has excellent cavitation erosion resistance.

[0005]

The invention according to claim 1 for solving the above problems, there is provided a means for solving] is provided with a pilot portion having a main valve portion and the poppet valve and the valve seat having a main valve and a valve seat, the main
When the poppet valve is opened by the pressure of the liquid as the working fluid flowing into the pilot portion from the valve portion, the main valve of the main valve portion is separated from the valve seat, and the working fluid flows out of the gap between the main valve and the valve seat. A relief valve of the balance piston type for adjusting the pressure of the hydraulic fluid to a predetermined constant pressure.
Form a throttle section consisting of multiple stages at the opposite part of the valve and valve seat
At the same time, the working fluid flowing from the main valve to the pilot
A multi-stage throttle section provided in the main valve and the pilot section
Valve seat that faces the poppet valve through the throttle provided in the
Of the main valve in the main valve section.
The liquid contact part and the pie at the part where the throttle part of the valve seat facing part is formed
The wetted part of the poppet valve in the lot part is made of ceramic or carbide.
Composed of gold or coated with ceramic or cemented carbide
Characterized in that the coating.

As described above, the main valve of the main valve section and the valve seat are opposed to each other.
The main part is formed by forming a multi-stage narrowed part
The working fluid in the gap between the main valve of the valve and the opposite part of the valve seat
Reduced pressure reduces cavitation
You. Also, the working fluid flowing from the main valve section to the pilot section
Is a multi-stage throttle provided in the main valve and the pilot
Valve that faces the poppet valve through the throttle provided in the section
The working flow is made by flowing into the liquid passage hole of the seat.
Cavitation occurs because the body is gradually decompressed
Is suppressed. In addition, the throttle of the valve seat facing part of the main valve of the main valve part
Part where the part is formed and the poppet part of the pilot part
The wetted part of the valve receives cavitation erosion.
Since this is an easy part, this part is
Composed of gold or coated with ceramic or cemented carbide
Cavitation resistance
The operability is improved .

[0007]

[0008]

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing the overall structure of the relief valve of the present invention. Although water is used as the working fluid in the present embodiment, the working fluid is not limited to water, and may be a liquid having a saturated vapor pressure and a viscosity close to that of water. As shown in FIG. 1, the relief valve includes a main valve portion A and a pilot portion B.

The main valve section A includes a casing 10, a main valve 11, and a valve seat 12. The valve seat 12 is fixed to a hole provided in the casing 10 via an O-ring 14 and a washer 13, and the main valve 11 is supported in a hole provided in the casing 10 by a wear ring (bearing) 15 and moves up and down at a predetermined stroke. It can move.

A coil spring 17 is disposed between the upper part of the main valve 11 and the casing 30 of the pilot section B, and the main valve 11 is attached to the valve seat 12 by the elastic force of the spring 17. It is being rushed. Reference numeral 16 denotes a packing for maintaining airtightness between the inner surface of the casing 10 and the outer peripheral surface of the main valve 11.

The pilot section B includes a casing 30, a poppet valve 31, a valve seat 32, a throttle member 33, a holding member 34, and a holding member 35. The valve seat 32 is fixed by a holding member 34 with a throttle member 33 interposed therebetween. A coiled spring 36 is disposed between the poppet valve 31 and the holding member 35, and the poppet valve 31 is urged toward the valve seat 32 by the elastic force of the spring 36.

The anti-poppet valve 31 of the spring 36
A spring seat 38 is provided at an end on the side of the side. The spring seat 38 rotates a pressure setting handle 37 to advance and retreat in a hole provided in the holding member 35, and the spring 36 applies an elastic force to the poppet valve 31. The power can be adjusted. The poppet valve 31 is supported at one end by a leaf spring 39 fixed to the casing 10.

A plate member 50 is provided on the main valve portion A on the side opposite to the pilot portion B of the casing 10, and a water passage hole 19 penetrating through the plate member 50 and passing through the center of the valve seat 12 is provided. The water passage hole 19 communicates with a water passage hole provided in the multistage throttle portion 18 provided at the center of the main valve 11, and communicates with a secondary pressure chamber 20 formed at the rear end of the main valve 11. I have.

FIG. 2 is a view showing a sectional structure of the main valve 11. A flange 11a and a flange 11b are formed at a front end (lower end in the figure) of the main valve 11 at a predetermined interval in order to form a two-stage throttle, and a multi-stage throttle 1 provided at the center thereof is provided.
Reference numeral 8 is composed of aperture members 18-1, 18-2 and 18-3.
As will be described in detail later, the outer surfaces of the flanges 11a and 11b and the portion 11c connecting the flanges 11a and 11b are liquid contacting portions where cavitation is likely to occur in the working fluid, and thus are susceptible to cavitation erosion. Therefore, this portion is integrally formed of a ceramic material.

A water hole 18 is provided at the center of the throttle member 18-1.
-1a is formed, a water passage hole 18-2a is formed at the center of the throttle member 18-2, and a water passage hole 18-3a is formed at a position off the center of the throttle member 18-3. I have.
The cross-sectional area of each water hole is (cross-sectional area of water hole 18-1a)>
(Cross-sectional area of water passage hole 18-2a)> (Cross-sectional area of water passage hole 18-3a). Aperture member 18-3 and aperture member 18-2
A secondary pressure chamber 29 is provided therebetween.

FIG. 3 is a diagram showing a sectional structure of the poppet valve 31 and the valve seat 32. As will be described later in detail, the outer surfaces of the poppet valve 31 and the valve seat 32 are liquid contact portions where cavitation is likely to occur in the working fluid, and thus are susceptible to cavitation erosion. Therefore, this poppet valve 31
Is also formed of a ceramic material.

In the relief valve having the above structure, the main valve portion A
The water passage hole 19 of the valve seat 12 communicates with high-pressure water such as a hydraulic pump, and the high-pressure water is, as shown in FIG.
8, the water passage holes 18-3a, 2-3 of the throttle member 18-3,
The secondary pressure chamber 2 passes through the secondary pressure chamber 29, the water hole 18-2a of the throttle member 18-2, and the water hole 18-1a of the throttle member 18-1.
0 (see FIG. 1) and further into the water passage hole 32a of the casing 30 of the pilot section B.

Here, the water pressure in the water passage hole 32a is
When the spring force for urging 1 is smaller than the resilience, the water pressure hole 32a of the valve seat 32 is closed by the poppet valve 31. With the same pressure, the main valve 11 is pushed by the elastic force of the spring 17, and the flange 11 a at the tip of the main valve 11 abuts against the valve seat 12 and closes. Therefore, the high-pressure water in the water hole 19 of the valve seat 12 does not flow to the water hole 27.

The water pressure in the water passage hole 19 rises, and the water passage hole 32a
When the water pressure becomes larger than the spring force of the spring 36, the poppet valve 31 is pushed by the water pressure and separates from the valve seat 32. As a result, the high-pressure water flows through the water passage 32a, the water passage 42, the water passage 43, and the water holes 25, 26, 27, and 28 to the water tank.

At this time, the high-pressure working water is supplied to the water passage hole 18-3a of the multistage throttle member 18-1 provided at the center of the main valve 11, the secondary pressure chamber 29, and the multistage throttle members 18-2 and 18-1. The secondary pressure chamber 20 passes through the water holes 18-2a and 18-1a.
However, since the pressure does not drop rapidly but drops stepwise, the occurrence of cavitation is suppressed, and problems such as vibration and impact are not given to the main valve 11. Therefore, the operation of the main valve 11 is stabilized. Also, when the water flows through the water passage hole 32a and flows into the water passage chamber 42, since the pressure is reduced in the water passage hole 32a, the occurrence of cavitation is suppressed, but cavitation is easily generated and cavitation erosion can occur. The sex is great. Therefore, in the present embodiment, the poppet valve 31 is made of a ceramic material.

The pressure of the working fluid (water) rises and the valve seat 32
When the amount of water flowing through the water passage hole 32a increases,
Since the water pressure in the next pressure chamber 20 drops, the water pressure in the water passage hole 19 overcomes the elastic force of the spring 17 and the main valve 11 rises. As a result, the high-pressure water in the water passage hole 19 is supplied to the flanges 11 a and 11 b and the valve seat 1 forming a two-stage throttle at the tip of the main valve 11.
It flows through the gap between the two and further through the water holes 27, 28 to the water tank.

FIG. 4 shows a state where the main valve 11 is separated from the valve seat 12. When the main valve 11 is in contact with the valve seat 12, the lower surface of the flange 11 b contacts the upper surface of the cylindrical projection 12 a of the valve seat 12 to close the water passage chamber 12 b communicating with the water passage hole 19. When the main valve 11 is separated from the valve seat 12, the valve seat 12
A gap a is formed between the lower surface of the flange 11a and the lower surface of the flange 11b.
Between the lower surface of the cylindrical projection 12a and the upper surface of the cylindrical projection 12a. High-pressure water from the water passage hole 19 is supplied to the water passage chamber 10a surrounded by the throttle gap a, the water passage chamber 12b, the throttle gap b, the outer periphery of the main valve 11 and the cylindrical projection 12a, and the inner surface of the casing 10.
The pressure is reduced step by step and flows to the water passage hole 27.

As described above, the high-pressure water from the water passage hole 19 is gradually reduced in pressure through the throttle gap a, the water passage chamber 12b, the throttle gap b, and the water passage chamber 10a, so that the occurrence of cavitation is suppressed. However, since the high-pressure water is decompressed in this portion, cavitation is likely to occur and cavitation erosion is likely to occur. Therefore, in the present embodiment, the flanges 11a and 11b of the main valve 11 and the portion 11c connecting the flanges 11a and 11b are integrally formed of a ceramic material.

In the above embodiment, the flange 11a, the flange 11b, the connecting portion 11c, and the poppet valve 31 constituting the tip of the main valve 11 are made of ceramic. By forming the portions of the valve material of the main valve portion A and the valve seat 32 of the pilot portion B that are in contact with the working fluid with ceramic, the cavitation erosion resistance can be improved.

Further, in the above-described embodiment, in order to improve the cavitation erosion resistance, the liquid contact portion of the portion where cavitation is likely to occur is made of ceramic, but a cemented carbide may be used instead of ceramic. That is natural. Further, instead of forming the entire liquid contact portion of the portion where cavitation is likely to occur from ceramic or cemented carbide, the surface of the liquid contact portion in contact with the working fluid may be coated with ceramic or cemented carbide.

In the above embodiment, the flange 11a, the flange 11b and the connecting portion 11c constituting the tip of the main valve 11 are made of ceramic. However, the simple main valve 11 having such a structure that cavitation easily occurs. By using only the tip portion of the ceramic as the ceramic, there is an advantage that a complicated portion of another structure can be processed without lowering the processing accuracy.

Further, in the relief valve having the above-described structure, corrosion resistant to the working fluid (here, water) is dealt with by using non-rusting steel for a liquid contacting portion in contact with the working fluid except for a portion where cavitation is likely to occur. It becomes possible.

In the above embodiment, the flange 11a and the flange 11b are formed on the main valve 11 of the main valve portion A and the main valve 11 at the opposite portion of the valve seat 12, so that a two-stage throttle portion is formed. The configuration of the squeezing section is not limited to this.
Needless to say, a multi-stage throttle unit as disclosed in the specification and the drawings of -148038 may be used.

[0030]

As described above, according to the present invention, the following excellent effects can be expected . Main valve of main valve and valve
When a narrowed section consisting of multiple steps is formed at the opposite part of the seat,
The working fluid flowing from the main valve section to the pilot section is
The multistage throttle section provided in the inside and the pilot section
Through the valve seat opposite the poppet valve through the
It is designed to flow into the liquid hole, and the working fluid is gradually
Reduced pressure reduces cavitation
You.

Also, a throttle portion at a portion of the main valve that faces the valve seat of the main valve.
In the liquid-contact part of the part where the pit is formed and the poppet in the pilot part
The liquid contact part of the valve is made of ceramic or cemented carbide or the liquid contact part
That the part is coated with ceramic or cemented carbide
Thereby, the cavitation erosion resistance is improved .

[Brief description of the drawings]

FIG. 1 is a sectional view showing the overall structure of a relief valve according to the present invention.

FIG. 2 is a view showing a sectional structure of a main valve of the relief valve of the present invention.

FIG. 3 is a view showing a cross-sectional structure of a poppet valve and a valve seat of the relief valve of the present invention.

FIG. 4 is a sectional view showing a state in which a main valve of the relief valve of the present invention is separated from a valve seat.

[Explanation of symbols]

 Reference Signs List A Main valve portion B Pilot portion 10 Casing 11 Main valve 12 Valve seat 15 Wear ring 16 Packing 17 Spring 18 Restricted portion 30 Casing 31 Poppet valve 32 Valve seat 33 Restricted member 34 Press member 35 Press member 36 Spring 37 Pressure setting handle 38 Spring Seat 39 leaf spring

Continuation of front page (56) References JP-A-56-147970 (JP, A) JP-A-61-62682 (JP, A) JP-A-6-53873 (JP, U) JP-A 64-4962 (JP) , U) JP 3-50149 (JP, B2) JP 39-21723 (JP, B1) JP 2-25490 (JP, Y2) JP 55-50453 (JP, Y2) (58) Field surveyed (Int.Cl. ⁷ , DB name) F16K 17/00-17/168 F16K 31/12-31/42

Claims (1)

(57) [Claims] 1. A main valve portion having a main valve and a valve seat, and a poppet.
A pilot section having a valve and a valve seat,From main valve
Flow into the IlotDue to the pressure of the working fluid,
When the poppet valve opens, the main valve of the main valve part
Hydraulic fluid flows out of the gap between the main valve and the valve seat.
A balun that keeps the working fluid pressure at a certain constant pressure
In the piston type relief valve,The main valve portion of the main valve portion and the valve seat opposite to each other have a plurality of throttles.
And a pilot section from the main valve section to the pilot section.
The working fluid that flows in is a multi-stage throttle section provided in the main valve.
And a throttle section provided in the pilot section.
Now flows into the liquid hole of the valve seat opposite the pet valve
And A portion of the main valve portion in which a throttle portion of a valve seat facing portion of the main valve is formed.
Liquid contact part and the liquid contact part of the poppet valve of the pilot part
Composed of ceramic or cemented carbide, or a ceramic
Or coated with cemented carbide Characterized by
Relief valve.