JPH0477924B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a pressure reducing valve that is attached to a fluid piping system for compressed air or the like 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 the 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 certified pressure with high precision.

Prior Art For example, as shown in FIG. 3, a conventional pneumatic pressure reducing valve has a main body 101 having an inlet 90 and an outlet 91.
A casing is formed by a bonnet member 109 containing a pressure adjustment spring 108, a valve body 102 biased toward the valve seat 92 by a valve spring 104 is arranged in the main body 101, and the valve body 102 and the stem 103 are connected. , the upper end of the stem 103 is brought into contact with a relief valve seat 107 that is screwed to the diaphragm 105 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 and the valve body 102 is opened via the stem 103, so that 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. The pressure is released to the outside of the casing through the relief hole 93 in the relief valve seat 107 and the relief hole 94 in the bonnet member 109, and the secondary pressure is maintained at a predetermined set pressure.

Problems to be Solved by the Invention In this case, there was a problem in that the fluctuation range of the secondary side pressure was large and the secondary side pressure could not be accurately maintained at a predetermined value. In other words, the set pressure is determined by the balance between the fluid pressure on the secondary side and the spring force.
This is because this set pressure is precisely a value with a certain range. As shown by the dashed line in the relationship between the set pressure and the actual outlet pressure in Figure 2,
The secondary side pressure is released from the relief valve seat only when it exceeds the set pressure center value and reaches the set pressure upper limit, and conversely, it is not released from the high pressure primary side until it falls below the set pressure center value and reaches the set pressure lower limit. Pressure fluid is replenished. 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, a technical problem of the present invention is to reduce the width of the set pressure value, thereby reducing the range of fluctuation of the secondary side pressure, and maintain the secondary side pressure at a predetermined value with high accuracy.

Technical Means for Solving the Problems The technical means of the present invention aimed at solving the above technical problems is to apply secondary side pressure to one side of the pressure-responsive member and apply pressure adjustment means to the other side. In a pressure reducing valve that opens and closes a main valve port by connecting 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. a relief valve port is formed at a position opposite to the relief valve body, the relief valve body and the valve casing are fixed with a bellows, and the bellows and the relief valve body are brought into contact with each other. forming a pressure space,
An introduction path for introducing secondary side pressure is connected to the pressure space and the relief valve port, and a communication path is provided to communicate the relief valve port and the atmosphere outside the system when the relief valve body is opened. A biasing means for biasing the body toward the opposite side of the relief valve opening is provided.

Operation: When the secondary pressure becomes equal to the set pressure adjusted by the pressure adjustment means, the pilot member and the sub-pilot member that transmit displacement to the main valve body are freed from the action of the high-pressure fluid on the primary side. A biasing force is applied to the sub-pilot member in a free state through 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 side 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 so that they are no longer in a free state and are relieved by the sub-pilot member. While the valve body closes the relief valve port, the main valve body is opened by the pilot member to supply high-pressure primary side fluid to the secondary side. A portion of the secondary pressure reaches the pressure space formed by the bellows and the sub-pilot member through the introduction path, 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 sub-pilot member and the biasing force of the biasing means act on the relief valve body, regardless of the secondary side pressure. As shown by the solid line in the relationship between set pressure and actual outlet pressure in Figure 2, the outlet pressure does not fluctuate from the set pressure center value to the set pressure upper limit value, but immediately moves toward the set pressure lower limit value. Due to the variation, the width of the set pressure value is halved.

Effects of the invention Regardless of the secondary side pressure, when high pressure primary side fluid acts on the sub-pilot member, the relief valve port closes, and as soon as it stops acting, the relief valve port opens and the secondary side pressure is released to the atmosphere. By discharging, the width of the set pressure value is halved, and the fluctuation width of the secondary side pressure is also halved, making it possible to maintain the secondary side pressure with high accuracy.

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

A main body 8 having a fluid inlet 1 and an outlet 2, a main valve port 3, a piston chamber 5 for accommodating a piston 4 as a pilot member, a relief valve section 15, a pilot valve section 9, and a diaphragm chamber 10. The pilot body 12, the cover 13 that accommodates the pressure adjustment spring 11, and the lid member 14 of the body 8 form a valve casing.

The relief valve section 15 includes a sub-piston 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 20 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. The relief valve port 21 and the pressure space 17 are connected to the secondary pressure section through the introduction passage 18. Relief valve body 16 and relief valve lid 1
A coil spring 22 as a biasing means is provided between 9 and 9 to bias the relief valve body 16 in the direction in which the relief valve port 21 is opened. A communication passage 23 is provided in a part of the main body 8 on the outer periphery of the relief valve port 21, which communicates with the atmosphere outside the system when the relief valve port 21 is opened.

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

A main valve body 34 biased toward the main valve port 3 by a coil spring 33 is disposed on the inlet 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. By making this escape hole an appropriate size, the sub-piston 6 does not necessarily need an escape hole.

A portion of the fluid flowing in from the inlet 4 passes through the pilot inlet passage 30 and reaches the pilot valve portion 9. The pressure on the outlet 2 side, that is, on the secondary side, reaches the diaphragm chamber 10 through the inlet passage 18 and the pilot outlet passage 38. When the secondary side pressure becomes equal to the set pressure center value, the diaphragm 31 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 sub-piston chamber 7 is cut off, and the piston 4 and the sub-piston 6 become free. When the auxiliary piston 6 as the auxiliary pilot member becomes free, the relief valve body 16 is separated from the relief valve port 21 by the coil spring 22, and the secondary side pressure is released from the communication path 23 to the outside of the system.
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 displacing the sub piston 6 toward the relief valve port 21 side. As a result, the relief valve body 16 closes and the main valve body 34 is also pushed down, supplying high pressure fluid on the primary side to the secondary side.

By repeating the above operation, the secondary side pressure will not reach the set pressure upper limit, and therefore,
The width of the set pressure is halved, and the secondary pressure can be maintained at a predetermined value with high accuracy.

[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: Inlet, 2: Outlet, 3: Main valve port, 4: Piston, 6: Sub-piston, 7: Sub-piston chamber, 8: Main body, 9: Pilot valve part, 11: Pressure adjustment spring,
15: Relief valve part, 16: Relief valve body, 1
7: Pressure space, 18: Introduction path, 20: Bellows,
21: Relief valve port, 22: Coil spring, 23:
Communication path, 31: diaphragm.

Claims (1)

[Claims] 1 Pressure reduction that applies secondary side pressure to one side of the pressure responsive member and connects the pressure adjusting means to the other side to 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 valve, an auxiliary pilot member is provided that is separate from a pilot member that transmits displacement to the main valve element, and the auxiliary pilot member and the relief valve element are brought into contact to form a relief valve port at a position opposite to the relief valve element. Then, the relief valve body and the valve casing are fixed with a bellows, a pressure space is formed by the bellows and the auxiliary pilot member, and an introduction path for introducing secondary side pressure into the relief valve opening is connected to the pressure space. A pressure reducing valve, which is provided with a communication path that communicates the relief valve port with the atmosphere outside the system when the valve body is opened, and is provided with a biasing means that biases the relief valve body toward the opposite side of the relief valve port. Relief mechanism.