JPH0731558B2 - Pilot type pressure reducing valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a pressure reducing valve which is attached to a fluid piping system to reduce a fluid pressure on a primary side to maintain a fluid pressure on a secondary side at a predetermined set pressure, The present invention relates to a pilot type pressure reducing valve.

<Prior Art> As a conventional general pilot type pressure reducing valve
There is one disclosed in Japanese Patent No. 48211. This is because the high pressure fluid supplied from the inlet connected to the primary side flows out to the secondary side when the main valve is moved downward and opened due to the pressure drop on the secondary side connected to the outlet. It is designed to compensate for the drop in pressure. The main valve is opened by lowering a piston controlled by an upper pilot valve, a diaphragm associated with the pilot valve, a spring for pressure setting, and the like, and is closed by raising the piston.

<Problems to be Solved by the Invention> The above pressure reducing valve has a small flow rate when the set pressure (secondary side pressure) is small with respect to the primary pressure, that is, when the pressure reducing ratio is large, or the opening of the main valve is small. Occasionally causes a remarkable chattering phenomenon.

The pressure reduction ratio is, for example, 10 Kg / cm ² for the primary pressure and 2 for the secondary pressure.
This is the case where the pressure is reduced to about ² kg / cm ² or less, and the movable parts such as the main valve and piston vibrate, causing chattering.
This is because the secondary pressure drops and the change in pressure opens the pilot valve through the diaphragm, and the piston pushes down the main valve to open the valve port and supply the primary fluid to the secondary side. Measure the rise. However, at this time, the pressure difference between the primary side and the secondary side is large, and as shown by the curve A in FIG. Since there is a relation that a large flow rate is produced at, the secondary side pressure instantly rises, and that pressure causes the pilot valve to close rapidly via the diaphragm. If the pilot valve is closed rapidly, the fluid to the upper part of the piston is also cut off suddenly, the piston rises rapidly and the main valve closes rapidly. If the main valve closes abruptly, the secondary pressure also drops sharply and the pilot valve opens again again via the diaphragm. The above process is accelerated and a large vibration state is exhibited.

In addition, the vibration causes the jet flow of the fluid toward the secondary side to act on the lower surface of the piston due to the rapid opening of the main valve, and pushes up the piston abruptly to collide with its upper wall, and the main valve follows the rise of this piston. It is considered that it is not possible to do this, and the piston collides when the piston descends again. The re-contact is shocking, and such operation of the main valve and the piston has a problem that the piston is damaged or the main valve is damaged. Due to the damage of these members, the secondary pressure cannot be set or the life of the pressure reducing valve is shortened.

Therefore, a technical problem of the present invention is to provide a pressure reducing valve capable of handling a small flow rate to a large flow rate without causing a chattering phenomenon.

<Means for Solving the Problems> The technical means of the present invention taken to solve the above technical problems include a plurality of valve openings provided between an inlet and an outlet,
A plurality of valve elements that are urged by springs that close each valve opening and closing, a plurality of pistons that are provided to open each valve element, and to reduce the secondary pressure. A pilot valve provided so as to open based on the above, a passage for introducing the primary side pressure fluid to the upper part of only the first piston among the plurality of pistons by opening the pilot valve, and the upper part of the first piston It is provided with pores that communicate the space with the upper space of another piston.

<Operation> The pilot valve opens and the high-pressure fluid on the primary side first
Is introduced into the upper part of the piston to provide a driving force to the first piston. The driving force of the first piston opens the corresponding main valve below the first piston, and the fluid on the primary side flows out to the secondary side. If the fluid on the primary side is introduced from the pilot valve to the upper part of the first piston, part of the fluid is introduced into the upper space of the other piston through the pores, but the flow rate is small and This piston does not generate enough driving force to open the main valve located below because it flows out of the gap between the cylinders. Therefore, the main valves other than the main valve corresponding to the first piston piston are closed. To maintain.

Since only one of the plurality of main valves is opened in this way, the flow rate of outflow is a small amount when viewed from the flow rate of the entire pressure reducing valve. Therefore, even if only one main valve is opened, the secondary side pressure does not rise instantaneously, and the pilot valve is not suddenly closed accordingly, so that the chattering phenomenon as described above does not occur.

If a large flow rate is not required, it can be achieved by opening only the main valve corresponding to the first piston, but if the secondary pressure drops because more flow rate is required than in this state,
The pilot valve is further opened to increase the supply amount to the upper part of the first piston. As the supply amount increases, the supply amount to the upper part of other pistons also increases through the pores, and the driving force of the piston is generated to open the corresponding main valve to increase the flow rate to the secondary side. If the pressure on the secondary side becomes higher, the pilot valve acts in the valve closing direction and the amount of fluid supply to the first piston decreases, and accordingly, the fluid supply to pistons other than the first piston also passes through the pores. It decreases and then loses drive power and the corresponding main valve begins to close.

<Example> An example showing a specific example of the above technical means will be described.
(Refer to FIG. 1 and FIG. 2) Although the embodiment shown below is an example in which two sets of pistons and main valves are incorporated, it goes without saying that more than that may be provided. The main body 2 forms an inlet 4, a first valve opening 6, and a second valve opening 8 and an outlet 10. The inlet 4 is connected to a high pressure fluid source on the primary side and the outlet 10 is connected to a low pressure area on the secondary side. The first valve opening 6 and the second valve opening 8 are formed by the valve seat members 12 and 14, and the main valve springs 16 and 18 elastically bias the respective inlet side ends of the first main valve 20 and the second valve opening 8. The main valve 22 is arranged, and the respective main valve shafts 20a, 22a are inserted into the sliding holes of the bottom member 24.

A first piston 26 and a second piston 28 corresponding to the first main valve 20 and the second main valve 22 are slidably arranged in respective cylinders 30 and 32, and a piston rod 26 formed at the lower part of the piston
b, 28b are brought into contact with the central protrusion of each main valve through the respective valve openings 6, 8. The member numbers 34a, b.36a, b are piston rings for maintaining airtightness between the piston and the cylinder, and are made of resin such as fluorinated ethylene resin. reference number
26c and 28c are orifices that connect the upper surface and the lower surface of the piston. Upper space of the first piston 26, that is, the piston chamber 26
a and the piston chamber 28a of the second piston 28 are communicated with each other through the pore 29,
Its size is equal to or slightly larger than the orifice 28c of the second piston 28. The above-mentioned two sets of piston diameter, valve opening inner diameter, and spring constant of the main valve spring are designed to be the same. Also, in the technology mentioned here, the airtightness between the piston and the cylinder is maintained, and a certain amount of fluid is allowed to escape by the orifice, but as another general technical means, the orifice is not formed and the peripheral surface of the piston is not formed. It may be a labyrinth structure provided in the.

Upper space of the inlet 4 and the first piston 26, that is, the piston chamber 26
A pilot valve 42 biased in a valve closing direction by a biasing spring 40 is arranged in a primary pressure passage 38 communicating with a. Diaphragm
44 is attached with its outer peripheral edge sandwiched between the flanges 46 and 48, the lower space of the diaphragm 44 communicates with the outlet 10 through the secondary pressure detection passage 50, and the lower surface of the diaphragm 44 has the valve rod 52 of the pilot valve 42. Abutting the end face of the head.

A pressure setting spring 56 is brought into contact with the upper surface of the diaphragm 44 via a spring seat 54, and its upper end is biased by an adjusting screw 60 screwed to a spring case 58.

When the adjusting screw 60 is turned to the left or right, the elastic force of pushing down the diaphragm 44 of the pressure setting spring 56 changes. This pressure setting spring 56
The diaphragm 44 is curved according to the secondary pressure acting on the lower surface of the diaphragm 44 with the elastic force of the reference value as the reference value, and the valve rod 52 is displaced to open the pilot valve 42. As a result, the primary side fluid pressure is introduced into the piston chamber 26a, and the first piston 26
Give driving force to. The driving force of the first piston opens the first main valve 20 corresponding to the lower side of the first piston to open the first valve opening 6
Through which the fluid on the primary side flows out to the secondary side.

If the fluid on the primary side is introduced from the pilot valve 42 into the piston chamber 26a of the first piston 26, a part of the fluid will have pores 29
Through the piston chamber 28a of the second piston through
At this time, the flow rate is small because the pressure reduction ratio is large and the opening of the pilot valve is small when the flow rate is small, and the amount of gas flowing out from the pores is small and the orifice of the second piston 28 is small.
It leaks from 28c. Therefore, the driving force for opening the second main valve 22 is not generated in the second piston. Therefore, the second main valve 22 remains closed.

Since only the first main valve 20 is opened as described above, the flow rate of outflow is small when viewed from the flow rate of the entire pressure reducing valve. This state is indicated by the curve B in the graph of FIG. 2, and the area B1 shows the relationship between the displacement of the main valve and the flow rate when the first main valve 20 opens. Therefore, even if only one main valve is opened, the secondary side pressure does not increase instantaneously but gradually increases, and the abrupt closing of the pilot valve associated therewith also disappears, and the chattering phenomenon as described above does not occur.

The first piston if you do not need too much flow
The flow rate can be covered by the operation of only the second main valve 20 corresponding to 26, but if the secondary side pressure decreases due to the need for a larger flow rate than this state, the pilot valve 42 is further operated by the action of the diaphragm 44. The valve is largely opened to increase the supply amount to the piston chamber 26a of the first piston. When the supply amount increases, the first piston 26 further descends to open the first main valve 20, and at the same time, the supply amount of the second piston 28 to the piston chamber 28a through the pore 29 also increases, driving the second piston. Power is generated.
Then, the second main valve 22 is opened to increase the flow rate to the secondary side. If this state is shown in the graph of FIG. 2, it will be the area of the curve B2. If the pressure on the secondary side increases as the flow rate increases, the pilot valve 42 acts in the valve closing direction and the amount of fluid supplied to the first piston 26 decreases, and the piston chamber 28a of the second piston 28 decreases.
As a result, the second piston loses the driving force and the second main valve 22 starts closing. However, the first main valve 20
Continues to open the valve at this time. Thus, the first
The piston is driven preferentially to open the first main valve and perform the pressure reducing action.

<Effect of the Invention> Since the chattering phenomenon is eliminated by the technical means of the present invention, members such as the piston and the main valve are not damaged, and the depressurizing action can be performed in a stable state. Further, since the chattering phenomenon is eliminated, the minimum adjustable flow rate can be set small, and a pressure reducing valve with a wide range of use can be provided.

[Brief description of drawings]

FIG. 1 is a sectional view of a pressure reducing valve showing an embodiment of the present invention, and FIG. 2 is a graph showing the relationship between the displacement of the main valve of the pressure reducing valve and the flow rate. 2: Main body, 4: Inlet, 6: First valve port 8: Second valve port, 10: Outlet, 20: First main valve 22: Second main valve, 26: First piston 28: Second piston, 29 : Pore 42: Pilot valve, 44: Diaphragm 56: Pressure setting spring

Claims (1)

[Claims] 1. A plurality of valve openings provided between an inlet and an outlet, a plurality of valve elements biased by a spring having a valve closing action so as to open and close each valve opening, and each valve element. Multiple pistons provided to open, a pilot valve provided to open when the pressure on the secondary side drops, and a pilot valve opening to allow the primary pressure fluid to flow among the multiple pistons. In the pilot type pressure reducing valve, the passage is introduced to the upper part of the first piston only, and the pores that connect the upper space of the first piston and the upper space of the other piston.