JPH049611Y2 - - Google Patents

Description

[Detailed description of the invention] <Related technical field> Among the operating parts of a pressure reducing valve, this invention relates to the improvement of the pilot, which is particularly prone to breakage or malfunction due to frequent operation.

<Prior art and its problems> The main valve operation of a pressure reducing valve is usually self-controlled by guiding the secondary pressure response displacement of the diaphragm or sometimes the bellows to the operation of the pilot valve, and applying the primary pressure to the operating piston of the main valve. However, since the diaphragm cannot be displaced for a very long time within its elastic limit, the pilot valve operating mechanism (hereinafter simply referred to as the pilot) has to be large, and the bellows, on the other hand, has a much smaller diameter. Although this is possible, permanent deformation may occur under excessive compression. The excessive compression is caused by an excessive rise in secondary pressure, such as due to leakage from the valve seat of the main valve, which acts on the bellows, which serves as a pressure receiving surface of the pilot.

<Purpose> The purpose is to propose a development result aimed at preventing damage to bellows caused by excessive compression.

<Configuration> The above purpose is to provide a bellows that faces the stem of the pilot valve at its telescopic movable end that responds to secondary pressure;
A pressure reducing valve comprising a coil spring that applies a biasing force in a direction opposed to the secondary pressure to the telescopic movable end via a spring stay, and a screw-fit sleeve and spindle coupling that adjustably set the biasing force of the spring. This is accomplished entirely in the pilot by providing the spindle tip and the spring stay with abutment surfaces which limit the maximum permissible displacement of the bellows movable end therebetween.

Regarding this configuration, it is particularly preferable in practice to align the axis including the pilot valve, bellows, coil spring, and sleeve and spindle coupling parallel to the bonnet mounting surface of the pressure reducing valve body. Together with this, it helps to significantly reduce the size of the entire pressure reducing valve.

<Specific example according to the illustrations> FIG. 1 shows the entire pressure reducing valve in cross section, and FIG. 2 shows details of the main parts.

In the figure, 1 is the pressure reducing valve body, 2 is the bonnet, and 3
is a bottom flange, 4 is a main valve, 5 is a main valve seat, 6 is a return spring, 7 is an operating piston of the main valve 4, and 8 is a cylinder liner.

The bonnet 2 also serves as a cylinder head that covers the opening of the cylinder liner 8 and is airtightly attached to the valve body 1, and the adjuster cover 9 and the threaded plug 10 are airtightly attached on the axis parallel to the mounting surface. The following pilot mechanism is incorporated inside it.

That is, 11 is a pilot valve, 12 is a pilot valve seat, 13 is a pilot spring, and 1 is a pilot valve.
4 is a bellows, 15 is a coil spring, 16 is a spring stay, 17 is a threaded sleeve, 18 is a spindle, 19 is a lock nut, 20 is a strainer, and 21 is a cap.

The bellows 14 is fixed to the bonnet 2 by an adjuster cover 9 with its open end sandwiched between gaskets, but there is a spring stay 16 inside, and a spring biasing force is applied to the other end of the bellows 14, that is, the movable end of the bellows 14 through this. coil spring 15,
A screw sleeve 17 and a spindle 18 are built in to adjust this spring biasing force, and when the screw sleeve 17 is pushed leftward, the coil spring 1 is
The biasing force against the telescopic movable end via the spring stay 16 of No. 5 is increased, and the reduction of the biasing force due to reverse rightward pullback is adjusted by rotating the spindle 18, and the set position is fixed by the lock nut 19.

By guiding the secondary side pressure of the pressure reducing valve main body 1 through the passage hole A opened in the bonnet 2 to the outer surface of the telescopic movable end of the bellows 14, any secondary pressure required for operation can be applied to the effective pressure of the bellows 14. By adjusting the set pressure that acts on the pressure-receiving surface and against which the above-mentioned biasing force should be balanced, it is possible to
The next pressure overwhelms the biasing force due to coil spring 15 and causes compression of bellows 14.

On the other hand, when the secondary pressure becomes lower than the set value, the biasing force overcomes the thrust force acting on the bellows 14 and expands, and the telescopic movable end engages with the stem of the pilot valve 11 opposite, resisting the pilot spring 13 and causing the pilot to close. Push valve 11 open.

The primary side pressure of the pressure reducing valve body 1 is introduced into the cylinder liner 8 through the passage holes B and C opened in the bonnet 2, and the pressure is introduced into the cylinder liner 8 by the operating piston 7, which has a much larger pressure receiving area than the main valve 4. The primary side pressure acting on the main valve 4 is overwhelmed to cause the valve seat 5 to be unseated and opened.

As a result, when the secondary side pressure rises, the bellows 14 is compressed and displaced accordingly, and the pilot valve 11 is restored to its seat, and the application of the primary side pressure to the operating piston 7 is stopped, so that the main valve 4 is reseated and closed. A valve is provided.

Needless to say, in the above operation, the operation of the main valve 4 is repeated to cancel out fluctuations in the secondary side pressure, and self-controlled control to maintain the secondary side pressure at the set value continues. .

There is a chance that an abnormal increase in the secondary pressure may occur, for example, due to leakage of the main valve 4 when the operation is stopped, but in this case, the bellows 14 is permanently deformed due to overcompression. This may cause the pilot's adjustment function to deteriorate.

To cope with this, abutting surfaces 18a and 16a are provided at the tip of the spindle 18 and the spring stay 16, which limit the maximum displacement allowed by the elastic limit of the movable end of the bellows 14 between them.

In the figure, 18b and 16b are receiving holes bored in the tip projection of the spindle 18 and the spring stay 16, which are useful for centering.

<Effect> When guiding the pilot operation of the pressure reducing valve that responds to the secondary pressure by the expansion and contraction displacement of the bellows, 2.
Breakage of the bellows due to overcompression of the bellows due to an excessive increase in the next pressure can be advantageously avoided, thereby ensuring proper operation of the pressure reducing valve with long-term durability.

[Brief explanation of the drawing]

FIG. 1 is a sectional view, and FIG. 2 is a detailed view of the main parts. 11... Pilot valve, 14... Bellows, 1
5... Coil spring, 16... Spring stay, 17... Threaded sleeve, 18... Spindle, 16a, 18a... Butt surface.

Claims (1)

[Claims for Utility Model Registration] (1) A bellows that faces the stem of the pilot valve at its telescopically movable end that responds to secondary pressure, and a biasing force that opposes the secondary pressure to the telescopically movable body through a spring stay. In the pilot of a pressure reducing valve consisting of a coil spring acting on the end, and a threaded sleeve and spindle connection for adjustable setting of the biasing force of the spring, the end of the spindle and the spring stay have a bellows between them. A bellows protection device for a pilot of a pressure reducing valve, characterized by having an abutment surface that limits the maximum permissible displacement of the movable end. (2) The pilot of the pressure reducing valve described in (1), wherein the axis including the pilot valve, bellows, coil spring, sleeve and spindle coupling is aligned parallel to the bonnet mounting surface of the pressure reducing valve body.