JPH0786780B2 - Pressure reducing valve - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a main valve structure of a pressure reducing valve which is attached to a pipe such as steam or compressed air to keep a fluid pressure on a secondary side at a constant set pressure.

2. Description of the Related Art A conventional main valve structure of a pressure reducing valve is, for example, as shown in FIG. 4, a main valve 61 is formed in a disc shape, an annular valve seat surface 62 is formed on an upper surface, and an upper valve seat 67 is formed. And the lower surface of the main valve 61 is a flat surface, and the cylindrical main valve shaft 63 is perpendicular to the surface and is cylindrical in the center.
Was used, and a projection 64 was provided on the upper surface of the main valve coaxially with the main valve shaft 63 and abutted against the lower portion of the piston rod 66. The main valve shaft 63 is inserted into a holder guide 68 of the separator, and a spring 69 is interposed between the lower surface of the main valve 61 and the holder guide 68.

Problems to be Solved by the Present Invention Since there is a certain amount of clearance between the main valve shaft 63 and the holder guide 68, pressure is applied to the flat surface portion of the main valve 61 by the flow of fluid, and the main valve shaft 63 has the above clearance. If the main valve 61 is tilted to the left and right within the range and the main valve 61 is closed in the tilted state, there is a problem that the valve seat surfaces are not connected uniformly and a valve leak occurs. The valve leakage will eventually lead to erosion damage to the valve and valve seat.

If the gap is made small so that the main valve shaft 63 does not tilt, the sliding resistance increases due to dust in the fluid, which causes the main valve shaft 63 and thus the main valve 61 to be caught. Further, since the lower surface of the main valve 61 is a flat surface perpendicular to the fluid direction, it is easily affected by a rapid change in the primary side pressure such as a water hammer.

Therefore, the technical problem of the present invention is to maintain a sufficient gap between the main valve shaft and its holder guide and prevent the main valve from tilting.

Means for Solving Problems The technical means of the present invention taken to solve the above problems is to form an inlet, a valve opening, and an outlet in a valve body, and to form a main valve facing the valve opening. The pressure responsive member is provided so as to interlock with the main valve, the pressure on the outlet side is applied to one surface of the pressure responsive member, and the desired load of the pressure setting means is applied to the other surface of the pressure responsive member so that the pressure on the outlet side is the set pressure. When the pressure drops below the level, the main valve opens and the high pressure fluid on the inlet side is replenished to recover the pressure.
When the main valve is closed when supply pressure becomes equal to the set pressure and the supply of high-pressure fluid is interrupted, the main valve is formed in a substantially hemispherical shape, and the upper end flat portion of the hemispherical main valve is used as the contact surface with the valve opening. ,
A main valve shaft is connected to the lower part of the main valve, and the main valve is arranged on the inlet side of the valve opening by a spring, and a tubular draining member is coaxial with the valve opening on the inlet side of the valve opening. Is formed, an insertion hole for the main valve shaft is formed in the center of the draining member, and the main valve shaft is slidably arranged in the hole.

The above-mentioned substantially hemispherical main valve includes a true sphere and a spheroid.

By providing the action draining member, the fluid from the inlet is rectified and passes through the hemispherical main valve portion. When the fluid passes through the hemispherical portion, the fluid force acting from the periphery toward the center acts, and the axis of the main valve overlaps with the center line of the valve opening. That is, when the hemisphere is on the center axis of the fluid, the flow velocity around the hemisphere is the same, but when it is deviated to the side, the flow velocity becomes uneven on the circumference, and the hemisphere is pushed back toward the center axis. Due to the pressure distribution, the main valve shaft overlaps with the center line of the valve opening.

Advantageous Effects of the Invention Since the main valve shaft is smoothly displaced along the central axis of the valve opening without tilting, the valve seat surface does not come into complete contact with the valve when the valve is closed, so that valve leakage does not occur.

Further, since the lower portion of the main valve is spherical, the impact force of the pressure fluctuation on the primary side such as a water hammer is reduced. Further, since the fluid resistance becomes small, the flow rate increases although it is slightly smaller than the conventional one.

Example An example showing a specific example of the above technical means will be described.

Example 1 (see FIG. 1).

In this embodiment, a pressure reducing valve for steam is shown. An inlet 2 and an outlet 3 are coaxially formed in the main body 1 and communicate with each other via a valve port 4. A piston 5 having a lower part formed in a hemisphere is slidably arranged in a cylinder 6, and a piston rod 7 is brought into contact with a protrusion 9 of a main valve 8 through a valve port 4. The main valve 8 is formed into a substantially hemispherical shape by cutting a true sphere slightly above the center, and its upper end flat portion serves as a contact surface with the valve port 4, and a main valve shaft 10 is formed in the lower portion.

The pressure on the upper surface of the piston 5 is controlled by the pilot valve 11.
The pilot valve 11 is arranged in a primary pressure passage 12 that communicates the inlet 2 and the upper space of the piston 5, that is, the piston chamber, and a diaphragm 14 as a pressure responsive member elastically biased by a pressure setting spring 13 as pressure setting means. Controlled through.
The lower end of the pressure setting spring 13 contacts the upper surface of the diaphragm 14, and the upper end of the pilot valve 11 contacts the lower surface. Diaphragm
The upper space of 14 communicates with the outside air through the passage 15, and the lower space communicates with the outlet 3 through the passage 16. The pressure setting spring 13 is biased by the adjusting screw 16. When the adjusting screw 16 is turned to the left or right, the elastic force of pushing down the diaphragm 14 of the pressure setting spring 13 changes. With the elastic force of the pressure setting spring 13 as a reference value, the diaphragm 14 bends according to the secondary pressure acting on the lower surface of the diaphragm 14 to open / close the pilot valve 11. As a result, the primary fluid is introduced into the upper space of the piston 5, that is, the piston chamber, the piston 5 is driven, and the main valve 8 is displaced,
The fluid at the inlet 2 flows down through the valve port 4 to the outlet 3, and the outlet 3
Bring side to desired pressure. When the fluid pressure on the outlet 3 side, that is, the secondary side, drops, the valve port 4 opens, and when it rises, the valve port 4 automatically operates so as to close.

In the space below the valve port 4, a draining member 17 having a generally cylindrical shape and a wide lower end is arranged, and a swirl vane 18 is provided on the outer peripheral surface of the middle abdomen thereof. A holder guide 19 is provided inside to insert the main valve shaft 10, and a main valve spring 20 is interposed.

The fluid entering from the inlet 2 is swirled around the lower outer periphery of the draining member 17 by the swirl vanes 18, the water droplets are swung out to the outside by centrifugal force, and the gas passes through the center of the draining member 17 to the valve port 4. Pass through there and exit at Exit 3. The centers of the valve port 4, the main valve 8 and the draining member 17 are all located on the same axis, and when the fluid passes through the hemispherical portion of the main valve 8, a fluid force acting from the surroundings toward the center acts and the valve port 4 The main valve shaft 10 is located on the central axis of the.

The action of the spherical surface of the lower part of the piston 5 on the jet flow from the valve opening 4 has the same effect as the lower part of the main valve 8, and the piston 5 is always positioned in the center. As a result, the piston 5 and the cylinder 6 perform a stable sliding action without being caught.

A drain valve port (23) communicating with the drain port (22) is formed at the bottom of the drain valve chamber (21) and covered with a float cover (24) to accommodate a spherical valve float (25) in a displaceable manner. A ventilation hole 26 is opened in the upper portion of the float cover 24. Therefore, the valve float 25 floats down along with the water level in the drainage valve chamber 21, opens and closes the drainage valve port 23, and automatically drains the water accumulated in the drainage valve chamber 21 to the outside.

Example 2 (see FIG. 2).

Although the lower surface of the piston 5 is a hemisphere in the first embodiment, the conventional flat piston is used in the second embodiment.

Example 3 (see FIG. 3).

As described above, since the main valve 8 works to be positioned in the center, in order to transmit this action to the piston 5, the lower portion of the piston rod 51 and the upper protrusion portion 52 of the main valve 8 are fitted with an uneven portion. As a result, the piston 5 also has the effect of keeping it upright.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the pressure reducing valve of the present invention, and FIG.
FIG. 4 is an enlarged sectional view of an essential part showing another embodiment of the pressure reducing valve of the present invention, FIG. 3 is an enlarged sectional view of an essential part showing an example of connection between a piston and a main valve of the pressure reducing valve of the present invention, and FIG. It is an important section expanded sectional view showing an example. 1: Main body, 4: Valve port 5: Piston, 6: Cylinder 8: Main valve, 10: Main valve shaft 11: Pilot valve, 14: Diaphragm 17: Drain member, 23: Discharge valve port 25: Valve float

Claims (1)

[Claims] 1. A valve body is provided with an inlet, a valve opening and an outlet, a main valve is arranged facing the valve opening, and a pressure responsive member interlocking with the main valve is provided, and one surface of the pressure responsive member is provided. The pressure on the outlet side is applied, and the desired load of the pressure setting means is applied to the other surface,
When the outlet side pressure drops below the set pressure, the main valve opens to replenish the inlet side high pressure fluid to recover the pressure, and when it becomes equal to the set pressure the main valve closes to replenish the high pressure fluid. In the case of interruption, the main valve is formed in a substantially hemispherical shape, the upper end flat portion of the hemispherical main valve is used as a contact surface with the valve opening, and the main valve shaft is connected to the lower portion of the main valve to connect the main valve. Is placed on the inlet side of the valve opening by a spring, and a tubular draining member is placed coaxially with the valve opening on the inlet side of the valve opening, and the main valve shaft of the main valve shaft is provided at the center of the draining member. A pressure reducing valve in which an insertion hole is formed and the main valve shaft is slidably arranged in the hole.