JPH11248031A - Poppet valve - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To suppress cavitation generated when a poppet moves and flows from a high pressure side to a low pressure side, and to reduce erosion and noise due to cavitation. SOLUTION: A body 1, an upstream port 3, a downstream port 4, formed in the body 1, a flow path connecting these two ports, and a sheet portion 12 located in the middle of the flow path.
A poppet 20 installed in the flow path in the axial direction, and a spring 8 for pressing the poppet 20 against the seat 12.
In the poppet valve provided with the above, when the poppet closes the seat portion 12, a groove 19 extending in the axial direction is formed in a portion located on the outer periphery of the poppet 20 and located upstream of the seat portion 12. did.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a poppet valve which opens and closes a flow path by moving a poppet.

[0002]

2. Description of the Related Art FIG. 4 shows a conventional poppet valve used as a balanced relief valve. This poppet valve forms a body B by incorporating a tubular member 1 and a tubular seat member 2 into a tubular housing h, and forms a pressure port 3 and an outflow port 4 in the seat member 2. I have. A main poppet 5 having an orifice 6 is slidably inserted into the sheet member 2. Further, the opening end of the body B is closed by a plug 7 assembled to the tubular member 1. Further, a pilot poppet sheet member 10 having an orifice 11 is incorporated between the cylindrical member 1 and the sheet member 2 to form a poppet chamber 15 between the pilot poppet sheet member 10 and the plug 7.

In this poppet chamber 15, a pilot poppet 9 having a conical tip is provided via a spring 8 so as to contact the pilot poppet sheet member 10. Normally, the pilot poppet 9 is pressed against the seat portion 12 of the pilot poppet sheet member 10 by the spring force of the spring 8. Further, a spring 13 is interposed between the main poppet 5 and the pilot poppet seat member 10 so that the main poppet 5 is normally pressed against the seat portion 2a of the seat member 2 by the spring force of the spring 13. I have to. A passage 14 is formed in the tubular member 1. The poppet chamber 15 communicates with the outflow port 4 from the passage 14 through the space between the inner periphery of the housing h and the outer periphery of the cylindrical member 1 and the sheet member 2.

In such a poppet valve, when a pressure is applied to the pressure port 3, the pressure acts on the main poppet 5, and the orifice 6 extends from the spring chamber 16 in the main poppet 5 to the orifice of the pilot poppet seat member 10. It also acts on the pilot poppet 9 via 11. If the pressure acting on the pilot poppet 9 is low, the pilot poppet 9 remains pressed against the seat portion 12 of the pilot poppet sheet member 10. However, if this pressure overcomes the spring force of the spring 8, the pilot poppet 9 moves. Then, the fluid from the pressure port 3 flows from the seat 12 to the poppet chamber 15.
Through the passage 14 to the outflow port 4. When such a flow occurs, a differential pressure is generated before and after the orifice 6 formed in the main poppet 5, so that the main poppet 5 is moved by this pressure difference, and the pressure port 3 and the outflow port 4 communicate with each other.

[0005]

When the pressure rises on the pressure port 3 side, the poppet valve first moves the pilot poppet 9 to generate a flow, and then the main poppet 5 moves.
Is configured to move. As described above, when the pilot poppet 9 moves and leaves the seat portion 12, as shown in FIG. 5, fluid from the high pressure side flows into the poppet chamber 15 via the seat portion 12, as indicated by an arrow a. As described above, at the moment when the seat portion 12 and the pilot poppet 9 are separated, the high-pressure jet flows into the poppet chamber 15 from the gap between the two, and rapidly releases the pressure. By this jet,
Cavitation occurs. When the poppet valve is a relief valve, cavitation is more likely to occur because the differential pressure across the seat 12 increases.

Moreover, this jet flows along the pilot poppet 9 as shown by an arrow a. For this reason, it is difficult for the flow to enter the corner portion 15a of the poppet chamber 15 located immediately downstream of the sheet portion 12, and this becomes a low pressure region. The formation of such a low pressure region increases the local pressure difference in the flow path, and further increases cavitation. If this cavitation occurs, erosion and noise will occur.

Further, the erosion damages the surface of the pilot poppet 9 and the pilot poppet sheet member 10, but the damage may result in a defective seat, and may not function as a poppet valve. In particular, when the poppet valve is a relief valve, if a seat failure occurs in the seat portion 12, the load pressure in a circuit (not shown) decreases, which is a serious problem. An object of the present invention is to suppress cavitation generated when a poppet moves and a flow from a high pressure side to a low pressure side occurs, thereby reducing erosion and noise due to cavitation. Another object is to prevent a poppet or a sheet portion from being damaged due to erosion and causing a sheet defect.

[0008]

According to a first aspect of the present invention, there is provided a poppet valve comprising: a body; an upstream port formed in the body;
A downstream port, a flow path communicating these two ports, a sheet portion located in the middle of the flow path, a poppet axially installed in the flow path, and a spring pressing the poppet against the sheet portion. In the poppet valve provided with, a groove extending in the axial direction is formed in a portion located on the outer peripheral portion of the poppet and located upstream of the seat portion in a state where the poppet is closing the seat portion. And
The second invention is characterized in that the axial cross section of the groove is arc-shaped.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS This embodiment shown in FIGS.
Pilot poppet 9 of the conventional poppet valve shown in FIG.
Instead of this, a pilot poppet 20 having a different shape is provided, and the other configuration is the same as the conventional one. Therefore, the whole will be described with reference to FIG.
As shown in FIG. 1, the pilot poppet 20 has a plurality of grooves 19 extending along the axial direction on the outer periphery of the conical tip side. The groove 19 is located upstream of the seat 12 with the pilot poppet 20 in close contact with the seat 12. Seat part 12
However, if the groove 19 is caught, the sheet cannot be formed, so that the groove 19 is not formed at a position corresponding to the seat portion 12. Also, this groove 19
Has an arc-shaped cross section in the axial direction as shown in FIG. Therefore, the grooves 19 can be easily formed by the rotary blades oriented in the axial direction.

[0010] The pilot poppet 20 as described above,
The seat 12 moves by the pressure from the pressure port 3.
Away from the high-pressure jet from the gap between the two
Flow into 5. Then, from the poppet chamber 15, the cylindrical member 1
Through the passage 14 formed in the outlet port 4.
Then, the effect that the main poppet 5 moves due to the differential pressure across the orifice 6 is the same as in the conventional example. In this embodiment, the pressure port 3 constitutes the upstream port of the present invention, and the outflow port 4 constitutes the downstream port of the present invention.

FIG. 2 shows a state in which the pilot poppet 20 of this embodiment is separated from the seat portion 12. The direction of the jet from the pressure port 3 changes along the arc of the groove 19 formed on the outer periphery of the pilot poppet 20 as shown by the arrow b. Therefore, the flow is also guided to the corner 15a of the poppet chamber 15, and does not create a low-pressure area in the corner 15a. Therefore, the occurrence of cavitation can be suppressed as compared with the conventional example in which the corner portion 15a has a low-pressure region. Therefore, erosion and noise due to cavitation can be reduced.

The flow path in the seat portion 12 is defined by the inner periphery of the seat portion 12 shown in the cross-sectional view of FIG.
0 is a ring-shaped portion surrounded by an outer periphery. The Reynolds number Re representing the flow state in this part can be obtained by the following equation. Re = L · U / ν where L is a representative dimension (length corresponding to the diameter of a circular tube) representing the size of the pipe cross section, U is the flow velocity, and ν is the kinematic viscosity of the fluid . However, since the flow between the pilot poppet 20 and the seat portion 12 is not a flow in a circular pipe,
As L, a value proportional to (flow path cross-sectional area A) / (flow path circumference s in the flow path cross section) can be used.

Since a large number of irregularities are formed on the outer periphery of the pilot poppet 20 by the grooves 19, the length s of the flow path circumference in the cross section of the flow path, that is, the so-called wet edge length is determined by the length of the grooves 19. The size is larger than that of the conventional example in which no element is formed. On the other hand, if the movement amounts of the pilot poppets 20 and 9 are the same, the flow path cross-sectional area A hardly changes. Therefore, there should be almost no difference in the flow velocity U as a whole. Under such conditions, in the pilot poppet 20 of this embodiment, since the groove 19 is formed, the length s of the flow path circumference in the cross section of the flow path is longer than the pilot poppet 9 of the conventional example. . While the outer circumference of the conventional pilot poppet 9 depends only on the poppet diameter,
In the case of the pilot poppet 20 of the present invention, the groove 19
Depending on the shape and the number, the outer circumference can be made larger. That is, the length of the wet edge can be increased.

If the wet edge length becomes longer, L in the above equation
Becomes smaller. Then, the Reynolds number Re decreases,
Cavitation can be reduced. Therefore, generation of erosion and noise due to cavitation can be suppressed. In this embodiment, the groove 19 is formed in the pilot poppet 20 so as to suppress cavitation caused by the flow generated when the pilot poppet 20 is opened. Applicable to relief valves of the type. In the case of a poppet provided in a flow path process connecting the upstream port and the downstream port, by forming a groove upstream from the sheet portion, cavitation generated when the poppet is opened can be suppressed. it can.

Although the poppet valve of this embodiment is a relief valve, the operation is the same for a poppet valve not used as a relief valve. However, in the case of a relief valve,
Since the pressure difference before and after the poppet increases, cavitation is likely to occur.In addition, if a sheet failure occurs, the load pressure decreases, and it is a serious problem that the poppet and the sheet may be damaged by erosion. is there. Therefore, the present invention provides a relief valve
It is particularly effective.

[0016]

According to the present invention, the cavitation generated when the poppet is opened can be suppressed by forming the groove extending in the axial direction of the poppet on the high pressure side of the poppet sheet portion. That is, by changing the flow direction of the jet flowing along the groove, eliminating the low pressure region, suppressing the occurrence of cavitation, increasing the wet edge length due to the unevenness of the outer periphery of the poppet, reducing the Reynolds number And the occurrence of cavitation is suppressed. Therefore, erosion due to cavitation and noise can be reduced. In addition, it is possible to prevent a sheet failure due to erosion of a poppet or a sheet portion.

According to the second aspect, the jet flow along the groove is more easily guided to the corner of the poppet chamber, and cavitation can be suppressed. Further, a groove having an arc-shaped cross section in the axial direction is easy to form. When the poppet valve is a relief valve, the pressure on the upstream side is high, and the pressure difference between before and after the poppet increases, so that cavitation is likely to occur. In addition, if a seat failure occurs in the seat portion of the relief valve, the load pressure is reduced, and it is a serious problem that the poppet and the seat portion are damaged by erosion. Therefore, the present invention is particularly effective for a relief valve.

[Brief description of the drawings]

FIG. 1 is an enlarged view of the vicinity of a seat portion of a pilot poppet of this embodiment.

FIG. 2 is an enlarged view of the vicinity of the seat portion in a state where the pilot poppet of this embodiment has left the seat portion.

FIG. 3 is an enlarged sectional view taken along the line III-III of FIG. 2;

FIG. 4 is a conventional poppet valve.

FIG. 5 is an enlarged view of the vicinity of the seat portion in a state where the pilot poppet of the conventional example has left the seat portion.

[Explanation of symbols]

 B Body 3 Pressure port 4 Outflow port 8 Spring 12 Seat section 19 groove 20 Pilot poppet

Claims (2)

[Claims] 1. A body, an upstream port formed in the body, a downstream port, a flow path communicating these two ports, a sheet portion located in the middle of the flow path, In a poppet valve including a poppet installed in an axial direction and a spring pressing the poppet against a seat portion, in a state where the poppet is closing the seat portion, an outer peripheral portion of the poppet and an upstream side of the seat portion. Wherein a groove extending in the axial direction is formed in a portion located at the position (1). 2. The poppet valve according to claim 1, wherein an axial cross section of the groove is arc-shaped.