JPH0477923B2 - - 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. It is released outside 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 side 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. That is, the set pressure is determined by the balance between the fluid pressure on the secondary side and the spring force, and this set pressure is precisely a value with a certain range. As shown by the chain 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 supplied 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, 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 transmitting the displacement of a pressure-responsive member to a main valve body through a pilot member, a telescopic member that cooperates with the pilot member is provided between the pilot member and the valve body. , a relief valve body is disposed at one end of the telescopic member, and the relief valve body is fixed to the valve casing via a bellows whose telescopic force is smaller than that of the telescopic member to form a pressure space, and the outer periphery of the pressure space is A communication path is provided to communicate with the atmosphere outside the system, and a relief valve seat is arranged at a position opposite to the relief valve body, so that when the pilot member is in a free state, the relief valve body is separated from the relief valve seat by an elastic member. The pressure on the secondary side is relieved to the atmosphere through the communication passage.

Function By disposing a relief valve element between the pilot member and the valve element that separates when the pilot member becomes free, when the secondary pressure becomes equal to the set pressure center value and the pilot member becomes free, The secondary pressure passes through the relief valve body to the outer periphery of the pressure space, and is immediately released to the atmosphere through the communication passage.
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 pilot member is no longer in a free state, the relief valve body closes and the main valve body opens to release the high pressure. Supply the primary side fluid to the secondary side. 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 By halving the width of the set pressure value, the fluctuation width of the secondary pressure is also halved, and the secondary pressure can be maintained with high accuracy.

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

In this embodiment, an example in which the present invention is used in a pilot type pressure reducing valve having a steam separator for separating moisture in compressed air and a discharge valve for discharging the separated moisture to the outside of the system is shown.

In FIG. 1, a pressure reducing section 1, a steam/water separator section 2, and a discharge valve section 3 form a pressure reducing valve.

The pressure reducing section 1 includes a main body 8 having a fluid inlet 4 and an outlet 5, a main valve port 6, a piston chamber 7 for accommodating a piston 22 as a pilot member, a pilot valve section 9, and a diaphragm chamber 10. It is formed by a pilot body 12 and a cover 13 that accommodates a pressure adjustment spring 11.

The steam/water separator section 2 includes a swirling blade 14 that swirls the fluid flowing in from the inlet 4 to separate steam and water by centrifugal force, and a partition wall member 15 that changes the flow direction of the gas from which water has been separated. Form.

The discharge valve section 3 includes a discharge valve chamber 16 in which separated moisture accumulates, a float 18 that ascends and descends depending on the level of the accumulated moisture to open and close the discharge valve port 17, and a structure that prevents the float 18 from shaking due to swirling flow. It is formed with a float cover 19.

The pilot valve section 9 of the pressure reducing section 1 is formed by a pilot valve body 20 and a stem 21 that transmits the movement of a diaphragm 25 to the pilot valve body 20.

A main valve body 33 biased toward the main valve port 6 by a coil spring 34 is disposed on the inlet 4 side of the main valve port 6. A retractable member 35 formed of a cylindrical bellows is attached between the main valve body 33 and the piston 22 as a pilot member, a relief valve body 36 is attached to one end by welding, and the other end is in contact with the lower end 37 of the piston 22. Movable wall 3
8 is also attached by welding and arranged to be expandable and contractible. A relief valve seat 42 is provided at a position opposite to the lower part of the relief valve body 36. A similarly cylindrical bellows 39 is telescopically attached to the upper part of the relief valve body 36 to form a pressure space 40 between it and the valve casing. The piston 22, the telescopic member 35, and the main valve body 33 are each separate bodies and are arranged on the same axis. A communication passage 41 that communicates with the atmosphere outside the system is provided in the main body 8 at the outer periphery of the pressure space 40 . Reference numerals 50 and 51 are relief holes that release the pressure inside the piston chamber 7 to the secondary side.

A part of the fluid flowing in from the inlet 4 passes through the pilot inlet passage 30 and reaches the pilot valve part 9, and the main stream is swirled by the swirling vanes 14, and water droplets with a large mass are swung out to the outside by centrifugal force. 8 into the discharge valve chamber 16.
The fluid from which the water droplets have been separated reaches the outlet 5 through the main valve port 6. The pressure on the outlet 5 side, that is, the secondary side, passes through the pilot outlet passage 31 to the diaphragm chamber 10.
reach. When the secondary side pressure becomes equal to the set pressure center value, the diaphragm 25 is balanced with the spring force of the pressure adjustment spring 11, and the pilot valve body 20 closes. When the pilot valve body 20 closes, the supply of primary side pressure to the piston chamber 7 is cut off, and the piston 22
becomes a free state. When the piston 22 as a pilot member becomes free, the telescopic member 35 that has been extended toward the main valve body 33 by the piston 22 contracts, pushing up the piston 22 and lifting off the relief valve body 36 from the relief valve seat 42. At the very least, the secondary side pressure is released from the outer periphery of the pressure space 40 and the communication passage 41 to the outside of the system. When the secondary side pressure decreases and reaches the set pressure lower limit value, the diaphragm 25 is displaced downward by the pressure adjustment spring 11 and the pilot valve body 20 opens, thereby pushing the piston 22 downward and the relief valve body 36 When the main valve body 33 is closed, the main valve body 33 is also pushed down, and the high pressure fluid on the primary side is supplied 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: Pressure reducing section, 2: Steam water separator section, 3: Discharge valve section, 4: Inlet, 5: Outlet, 6: Main valve port, 8: Main body, 9: Pilot valve section, 11: Pressure adjustment spring,
18: Float, 20: Pilot valve body, 21:
Stem, 22: Piston, 33: Main valve body, 35:
Expandable member, 36: relief valve body, 39: bellows, 40: pressure space, 41: communication path, 42: relief valve seat.

Claims (1)

[Claims] 1 Pressure reduction that applies secondary pressure to one side of the pressure-responsive member, connects the pressure adjustment means to the other side, and transmits 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, a telescopic member that cooperates with the pilot member is provided between the pilot member and the valve body, a relief valve body is disposed at one end of the telescopic member, and the relief valve body has a telescopic force smaller than that of the telescopic member. A pressure space is formed by being fixed to the valve casing via a bellows, a communication path is provided to communicate the outer periphery of the pressure space with the atmosphere outside the system, and a relief valve seat is arranged at a position facing the relief valve body. ,
A relief mechanism for a pressure reducing valve, in which when the pilot member becomes free, the relief valve element is unseated from the relief valve seat by the telescopic member and relieves the secondary side pressure to the atmosphere through the communication passage.