JPH0247705A - Relief mechanism for reducing valve - Google Patents

Abstract

PURPOSE:To keep the secondary-side pressure with a high accuracy by closing a relief valve hole at the time of action of a high-pressure primary-side fluid upon an auxiliary pilot member and opening the relief valve hole at the time of non-action to discharge the secondary-side pressure to the air. CONSTITUTION:With respect to a reducing valve, the valve casing consists of a main body 8 which has an inlet 1 and an outlet 2 for a fluid and is provided with a main valve hole 3, a piston chamber 5 where a piston 4 as the pilot member is stored, and a relief valve part 15, a pilot valve part 9 provided with a diaphragm chamber 10, a pilot main body 13, and a cover member 14 of the main body 8. A relief valve part 15 consists of an auxiliary piston chamber 7 where an auxiliary piston 6 is stored, the part of a pressure space 17, a leading-in path 18, etc., and a valve body 16 is arranged. The pressure space is formed with bellows 20 and the auxiliary piston 6, and a connection path 23 is provided. A pilot valve body 30 is closed to set the piston 4 and the auxiliary piston 6 to the free state to discharge the secondary-side pressure on the side of the outlet 2.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a pressure reducing valve that is attached to a fluid piping system for compressed air, etc. to maintain fluid pressure on the secondary side at a constant set pressure, and in particular, relates to a pressure reducing valve that is used to relieve secondary side pressure. The present invention relates to a relief mechanism for a pressure reducing valve that maintains fluid pressure on the secondary side at a constant set pressure with high precision.

BACKGROUND ART For example, as shown in FIG. 3, a conventional pneumatic pressure reducing valve has a casing formed by a main body 101 having an opening 90 and an outlet 91, and a bonnet member 109 containing a pressure adjustment spring 10B. The valve body 102 biased toward the valve seat 92 at 104 is arranged, and the valve body 102 and the stem 103
and connect the upper end of the stem 103 to the diaphragm 105.
There is one which is brought into contact with a relief valve seat 107 which is screwed together via a diaphragm receiver 106.

When setting the pressure, the spring force of the pressure adjustment spring 108 is adjusted by rotating the handle 111, and the secondary pressure acting on the lower surface of the diaphragm 105 is adjusted to balance this spring force.

When the secondary side pressure becomes lower than the set pressure, the diaphragm "105 is displaced downward by the pressure adjustment spring 108, opens the valve body 102 via the stem 103, and the high pressure fluid on the primary side is supplied to the secondary side. As a result, the secondary side is maintained at a predetermined set pressure.

On the other hand, when the secondary pressure becomes higher than the set pressure, the diaphragm 105 is displaced toward the pressure adjustment spring 108 due to the secondary pressure, and the stem 103 is separated from the relief valve seat 107, thereby reducing the secondary pressure. Relief valve seat 1
The secondary pressure is maintained at a predetermined set pressure by being released from the casing through the relief hole 93 in the bonnet member 109 and the relief hole 94 in the bonnet member 109.

Problems to be Solved by the Invention In this case, there was a problem in that the secondary pressure fluctuated so much that the secondary pressure could not be accurately maintained at a predetermined value. That is, the set pressure is determined by the balance between the fluid pressure on the secondary side and the spring force, and this is because the set pressure has a value that has a range that can be accurately fitted. As shown by the dashed-dotted line in the relationship between the set pressure and the actual outlet pressure in Figure 2, the outlet pressure is not released from the relief valve seat until it exceeds the set pressure center value and reaches the set pressure upper limit. On the contrary, the high-pressure primary side pressure fluid is replenished only when the set pressure falls below the set pressure center value and reaches the set pressure lower limit value. Therefore, the actual secondary side pressure fluctuates between the upper and lower set pressure limits, and cannot be accurately maintained at a predetermined value. This is particularly problematic when the outlet pressure must be precisely controlled.

Therefore, the technical problem of the present invention is to reduce the range of the set pressure value to reduce the fluctuations in the secondary pressure and maintain the secondary pressure at a predetermined value with high accuracy.

Technical Means for Solving the Problems The technical means of the present invention taken to solve the above technical problems is to apply secondary side pressure to one side of the pressure responsive member and connect pressure regulating means to the other side. In the pressure reducing valve that opens and closes the main valve port by transmitting the displacement of the pressure responsive member to the main valve body via the pilot member, a sub-pilot member is provided that is separate from the pilot member that transmits the displacement to the main valve body. , the sub-pilot member and the relief valve body are brought into contact with each other, a relief valve port is formed at a position facing the relief valve body, the relief valve body and the valve casing are fixed with a bellows, and the bellows and n]
A pressure space is formed by the pilot member, and an introduction path for introducing secondary side pressure is connected to the pressure space and the relief valve opening, and when the relief valve body is opened, the relief valve opening communicates with the atmosphere outside the system. The relief valve body is provided with a communication passageway and urging means for urging the relief valve body toward the opposite side of the relief valve port.

When the secondary side pressure becomes equal to the set pressure adjusted by the pressure adjusting means, the pilot member and the auxiliary pilot member that transmit displacement to the main valve body are in a free state without being acted on by the high pressure fluid on the primary side. A biasing force is applied to the auxiliary pilot member in the free state via the relief valve body in the opening direction of the relief valve port by the biasing means. Therefore, when the auxiliary pilot member and the relief valve body are separated from the relief valve port, the secondary pressure connected through the introduction path is released to the atmosphere through the communication path. When the secondary pressure is released to the atmosphere and reaches the set pressure lower limit, the pressure responsive member is displaced and the high pressure fluid on the primary side acts on the pilot member and sub-pilot member, causing them to no longer be in a free state, and are relieved by the sub-pilot member. The valve body closes the relief valve port, and the pilot member opens and closes the main valve body to supply high-pressure primary fluid to the secondary side. A part of the secondary side pressure passes through the introduction path, reaches the pressure space formed by the bellows and the pilot member, and reaches the relief valve opening. The secondary pressure is canceled out between the pressure space side and the relief valve port side via the relief valve body. Therefore, only the force from the auxiliary pilot member and the urging force of the urging means act on the relief valve body regardless of the secondary side pressure. As shown by the solid line in the relationship between the set pressure and the actual outlet pressure in Figure 2, the outlet pressure does not fluctuate from the set pressure center value to the set pressure upper limit, but immediately moves toward the set pressure lower limit. Due to the variation, the width of the set pressure value is halved.

Effects of the Invention Regardless of the secondary pressure, if high-pressure primary fluid acts on the auxiliary pilot member, the relief valve port closes, and when it stops acting, the relief valve port opens immediately and the secondary pressure is released to the atmosphere. By releasing the pressure, the width of the set pressure value is halved,
Even when the secondary pressure is fluctuating, it is halved and the secondary pressure can be maintained with high precision.

Embodiment An embodiment illustrating a specific example of the above technical means will be described (see FIG. 1).

A main body 8 has a fluid intake 1 and an outlet 2, a main valve port 3, a piston chamber 5 for housing a piston 4 as a pilot member, a relief valve part 15, a pilot valve part 9, and a diaphragm 10. A pilot main body 12, a cover 13 that accommodates the pressure adjustment spring 11, and a lid member 1 of the main body 8.
4 to form a valve casing.

The relief valve section 15 includes a piston chamber 7 that accommodates the sub-piston 6, a pressure space 17, an introduction path 18, and a relief valve lid 19. The sub-piston chamber 7 is provided in communication with the piston chamber 5, and a disc-shaped relief valve body 16 is disposed at the end of the sub-piston 6. The relief valve body 16 is attached to the main body 8 via a cylindrical bellows 20. A pressure space 17 is formed by the bellows 2Q and the sub-piston 6 as a sub-pilot member. A relief valve port 21 is provided coaxially with the sub-piston 6 and the relief valve body 16. A coil spring 22 as a biasing means is provided between the relief valve ports 2119 to bias the relief valve body 16 in a direction to open the relief valve port 21.

A communication path 2 is provided in a part of the main body 8 on the outer periphery of the relief valve port 21 and communicates with the atmosphere outside the system when the relief valve port 21 is opened.
3 will be provided.

The pilot valve portion 9 is formed of a pilot valve body 30 and a stem 32 that transmits the movement of a diaphragm 31 to the pilot valve body 30.

A main valve body 34 biased in the direction of the main valve port 3 by a coil spring 33 is arranged on the population 1 side of the main valve port 3. A screen 35 is attached to the inlet 1 side of the main valve body 34.

Reference numeral 36 is a relief hole that releases the pressure inside the piston chamber 5 to the secondary side. It is not necessary to rub this relief hole with an appropriate size.

Part of the fluid flowing in from the port 4 passes through the pilot port passage 37 and reaches the pilot valve portion 9 . The pressure on the outlet 2 side, that is, the secondary side, reaches the diaphragm 10 through the introduction passage 18 and the pilot outlet passage 3B. When the secondary pressure becomes equal to the set pressure center value, the diaphragm 3
1 is balanced with the spring force of the pressure adjustment spring 11, and the pilot valve body 30 closes. When the pilot valve body 30 closes, the supply of primary side pressure to the piston chamber 5 and the auxiliary piston chamber 7 is cut off, and the piston 4 and the auxiliary screws 6 are in a free state. When the auxiliary piston 6 as the auxiliary pilot member becomes free, the relief valve body 16 is unseated from the relief valve port 21 by the coil spring 22 and discharges the secondary side pressure to the outside of the system through the communication path 23.

When the secondary side pressure decreases and reaches the set pressure lower limit value, the diaphragm 31 is displaced downward by the pressure adjustment spring 11 and the pilot valve body 30 opens, thereby causing the secondary piston 6
is displaced toward the relief valve port 21 side, and the relief valve body 1
6 is closed (the two main valve bodies 34 are also pushed down, and the high pressure fluid on the primary side is supplied to the secondary side).

By repeating the above operations, the secondary side pressure does not reach the set pressure upper limit value, and therefore, the width of the set pressure is halved, and the secondary side pressure can be accurately maintained at the predetermined value.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a pressure reducing valve according to an embodiment of the present invention, Fig. 2 is a relationship between the set pressure of the pressure reducing valve and the actual secondary pressure, and Fig. 3 is a sectional view of a conventional pneumatic pressure reducing valve. be. 1: Population 2: Outlet 3: Main valve port 4: Piston 6: Sub-piston 7: Sub-piston to 8: Main body
9: Pilot valve part pressure adjustment spring relief valve body introduction path Noleaf valve port communication passage: Relief valve part: Pressure space: Bellows: ] Illumination spring: Diaphragm

Claims (1)

[Claims] 1. Apply secondary pressure to one side of the pressure-responsive member, connect pressure adjustment means to the other side, and transmit the displacement of the pressure-responsive member to the main valve body via the pilot member to open and close the main valve port. In the pressure reducing valve, a sub-pilot member is provided that is separate from a pilot member that transmits displacement to the main valve body, and the sub-pilot member and the relief valve body are brought into contact with each other, and a relief valve port is formed at a position opposite to the relief valve body. forming a pressure space, fixing the relief valve body and the valve casing with a bellows, forming a pressure space with the bellows and the auxiliary pilot member, and connecting the pressure space with an introduction path for introducing secondary side pressure into the relief valve port, A pressure reducing valve provided with a communication path that communicates the relief valve port with the atmosphere outside the system when the relief valve body is opened, and a biasing means that biases the relief valve body toward the opposite side of the relief valve port. relief mechanism.