CN114183567A

CN114183567A - Back pressure one-way valve

Info

Publication number: CN114183567A
Application number: CN202111589393.0A
Authority: CN
Inventors: 彭威旺
Original assignee: Wuhan Feituoke Industry Co ltd
Current assignee: Wuhan Feituoke Industry Co ltd
Priority date: 2021-12-23
Filing date: 2021-12-23
Publication date: 2022-03-15

Abstract

The invention relates to a back pressure one-way valve which comprises a valve body, a valve cap, an upper valve rod, a lower valve rod, a valve seat, a spring and an adjusting screw, wherein the valve cap is connected to the valve body, the spring is limited at the upper end of the valve cap through the adjusting screw, the upper valve rod is arranged at the lower end of the valve cap, the lower valve rod is movably connected to the lower end of the upper valve rod, the upper valve rod and the lower valve rod can be separated in the radial direction, the valve seat is arranged on the lower end conical surface of the lower valve rod, and the ratio of the projection area of any horizontal section on the sealing surface of the valve seat to the projection area of the horizontal section of a lower sealing cavity of the valve cap is 0.6-1.4. According to the invention, through the design of the upper and lower two-section valve rods, when the valve has back pressure, the upper valve rod and the lower valve rod are separated, and the set pressure of the spring is offset. And the ratio of the projection area of the horizontal section of the sealing surface of the valve seat to the projection area of the horizontal section of the sealing cavity under the valve cap is manufactured, so that the actual opening pressure of the valve is accurately measured.

Description

Back pressure one-way valve

Technical Field

The invention relates to the field of valve control, in particular to a back pressure one-way valve.

Background

Check valves, also known as check valves or back-up valves, are commonly used in hydraulic systems to prevent the reverse flow of a medium. When a medium in a system flows in a positive direction, if the pressure of the medium at an inlet is greater than the set pressure of the spring, the medium pushes away the valve core pressed by the spring to realize circulation; when the pressure of the medium at the inlet is smaller than the pressure of the spring or the medium flows reversely, the valve core is automatically closed.

In practice, however, the valve will have a back pressure, i.e. a certain pressure of the medium is also present at the outlet. When the valve is back-pressurized, the valve may be closed even if the outlet medium pressure is greater than the set pressure of the spring.

Disclosure of Invention

In order to solve the defects of the prior art, the invention provides a back pressure one-way valve which comprises a valve body, a valve cap, an upper valve rod, a lower valve rod, a valve seat, a spring and an adjusting screw, the valve body has an inlet passage and an outlet passage and a valve chamber communicating the inlet passage and the outlet passage, the valve cap is connected to the valve body, the spring is arranged in the upper cavity of the valve cap, the adjusting screw is arranged above the spring, and the compression amount of the spring is axially adjusted, the upper valve rod is arranged in the lower sealing cavity of the valve cap, the lower valve rod is movably connected to the lower end of the upper valve rod, the upper valve stem and the lower valve stem are axially separable, the valve seat is arranged on the lower valve stem, when the valve is closed, the valve seat and the tail end of the inlet channel form a sealing surface, and the ratio of the projection area of any horizontal section on the sealing surface of the valve seat to the projection area of the horizontal section of the lower sealing cavity of the valve cap is 0.6-1.4.

Further, the ratio of the projected area of any horizontal section on the sealing surface of the valve seat to the projected area of the horizontal section of the lower sealing cavity of the valve cap is 0.95-1.05.

Further, an annular groove is formed in the outer wall of the upper valve rod, and a sealing element is arranged in the annular groove.

Furthermore, a limiting shaft shoulder is arranged between the upper cavity and the lower sealing cavity of the valve cap.

Further, the lower extreme of going up the valve rod is provided with the guiding hole, the upper end of lower valve rod is provided with the arch, the arch with guiding hole clearance fit.

Further, a weak spring is arranged in the guide hole.

Further, go up the valve rod upper end and be provided with the intercommunication the discharge passage of guiding hole, the export intercommunication of discharge passage the last centre bore of valve cap, the export end is provided with the steel ball, the steel ball below is provided with elastic element.

Further, the valve cap is provided with a locking screw, and the locking screw is located above the adjusting screw.

The invention has the advantages that the design of the upper and lower two-section valve rods ensures that the upper and lower valve rods are separated under the back pressure to offset the set pressure of the spring; and controlling the ratio of the projection area of the horizontal section of the sealing surface of the valve seat to the projection area of the horizontal section of the sealing cavity under the valve cap, and accurately measuring the actual opening pressure of the valve.

Drawings

FIG. 1 is a schematic view of a back pressure check valve contemplated by the present invention;

FIG. 2 is a schematic structural view of a back pressure check valve contemplated by the present invention, showing the upper and lower valve stems separated when back pressure is present in the valve;

FIG. 3 is a schematic structural view of a back pressure check valve contemplated by the present invention, illustrating the valve open;

fig. 4 is another structural view of the back pressure check valve contemplated by the present invention, showing an anti-siphon structure.

Detailed Description

To facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings.

Referring to the attached figure 1, the invention comprises a valve body 1, a bonnet 2, an upper valve rod 3, a lower valve rod 4, a valve seat 5, a spring 9 and an adjusting screw 11. The valve body 1 comprises an inlet passage, an outlet passage and a valve chamber 10 communicating the inlet passage and the outlet passage, the valve chamber 10 opening upwards. The valve cap 2 is in threaded connection with the valve body 1, and an O-shaped ring 13 is arranged at the connection position of the valve body 1 and the valve cap 2. The spring 9 is arranged in an upper cavity 20 of the valve cap 2, the adjusting screw 11 is connected to the upper end of the valve cap 2 in a threaded mode, and the baffle 18 is arranged below the adjusting screw 11. The adjusting screw 11 is movable up and down relative to the bonnet 2 to adjust the amount of compression of the spring 9. Adjusting screw 11 upper end further can set up locking screw 12, and locking screw 12 threaded connection is on valve cap 2, and locking screw 12 can prevent adjusting screw 11 because of the vibration or the lax that the high pressure leads to.

The upper stem 3 is disposed in a lower packing chamber 22 of the bonnet 2, and the upper stem 3 is axially movable in the lower packing chamber 22. Preferably, an annular groove 34 is provided on the outer circumferential surface of the upper stem 3, and the sealing member 14 is provided in the annular groove 20. The packing 14 provides a reliable seal between the upper stem 3 and the lower packing chamber 22 of the bonnet 2 to prevent leakage of the medium. The lower stem 4 is movably connected to the lower end of the upper stem 3. In a preferred embodiment, the upper end of the lower stem 4 is provided with a protrusion 42, and the protrusion 42 is inserted into the guide hole 30 of the upper stem 3, and the protrusion 42 facilitates the engagement and disengagement of the upper and lower stems to provide a radial restriction. In order to facilitate the radial separation of the upper valve rod 3 and the lower valve rod 4, a weak spring 7 can be arranged in an inner hole of the upper valve rod 3, and the weak spring 7 can provide stable acting force after the upper valve rod 3 and the lower valve rod 4 are separated. To prevent the upper valve stem 3 from being forced out of the bonnet 2 by excessive media pressure, a stop shoulder 26 may be provided at the transition between the upper cavity 20 and the lower seal cavity 22.

The lower end of the lower stem 4 is tapered, the valve seat 5 is fixed to the tapered surface 46 of the lower stem 4 by the fixing screw 6, and the valve seat 5 is made of, but not limited to, PTFE, PCTFE, or the like. The adjusting screw 11 is rotated clockwise, the adjusting screw 11 compresses the spring 9, the spring 9 applies radial downward pressure to the upper valve rod 3 through the lower spring gasket 19, the upper valve rod 3 extrudes the lower valve rod 4, the valve seat 5 on the lower valve rod 4 is tightly attached to the conical surface 28 at the tail end of the inlet channel of the valve body 1, the valve is closed, and the valve seat 5 and the conical surface 28 form sealing surfaces (52, 54).

Assuming that F1 is an inlet pressure, F2 is an outlet pressure, and F3 is a set opening pressure, when the valve has a back pressure, referring to fig. 2-3, an outlet medium enters between the upper valve rod 3 and the lower valve rod 4 from the valve cavity 10 through a gap between the lower valve rod 4 and the lower end of the bonnet 2, and the outlet medium exerts an upward force on the lower end surface 31 of the upper valve rod 3 and a downward force on the upper end surface 41 of the lower valve rod 4. When F2 is larger than F3, the upper valve rod 4 is separated from the lower valve rod 3, and the lower valve rod 4 is separated from the pressure of the spring 9 and is only subjected to outlet medium pressure. At this time, if F1 > F2, the inlet medium lifts the lower valve rod 4 upward, the valve is opened, and the medium can flow from the inlet to the outlet normally. If F1 is more than F2, the valve is still closed, the outlet medium can not flow back to the inlet, and the valve plays a role in one-way flow limiting;

in order to ensure that the valve is normally opened under back pressure, the inlet pressure F1 should satisfy the equation F1 ═ Δ S ═ F2+ (F3-F2) × S, where Δ S is the ratio of the projected area S1 of any horizontal cross section on the sealing surfaces (52,54) of the valve seat 5 to the projected area S2 of the horizontal cross section of the lower sealing cavity 22 of the valve cap 2, and Δ S is 0.6 to 1.4. When Δ S < 0.6, assuming that the valve has a set opening pressure of 1MPa and an outlet pressure of 1MPa, the inlet pressure needs to be at least 1.67MPa to open the valve, i.e., the inlet pressure is greater than 67% of the outlet pressure and higher than the set opening pressure, resulting in unstable actual opening pressure. When Δ S > 1.4, assuming that the set opening pressure of the valve is 1MPa and the outlet pressure is 0.5MPa, the inlet pressure is only 0.86MPa, i.e. the inlet pressure + 28% of the outlet pressure > the set opening pressure, and the inlet pressure is higher than the outlet pressure, resulting in the actual opening pressure being lower than the set opening pressure.

In order to bring the actual opening pressure closer to the valve set opening pressure, the value of Δ S should preferably be controlled to be between 0.95 and 1.05. When Δ S is 0.95, assuming that the valve has a set opening pressure of 1MPa and an outlet pressure of 1MPa, the inlet pressure is greater than 5% of the outlet pressure, and the inlet pressure is higher than the set opening pressure, i.e., the inlet pressure is 1.05MPa, so that the valve can be opened. When Δ S is 1.05, assuming that the valve set pressure is 1MPa and the outlet pressure is 0.5MPa, the inlet pressure + 6% outlet pressure > the set opening pressure and the inlet pressure is higher than the outlet pressure, i.e., the inlet pressure is 0.97MPa only to open the valve.

Another aspect of the present invention is to provide a back pressure check valve with anti-siphon function, and referring to fig. 4 in particular, the upper end of the upper valve stem 3 is provided with a discharge passage 32 communicating with the cavity 20 on the valve cap 2. The lower end of the discharge channel 32 is provided with a steel ball 16, below which ball 16 an elastic element 17 is arranged, which elastic element 17 is defined by a partition 8 arranged in the guide hole 30. When the valve is in a closed state, if the outlet generates negative pressure, atmospheric pressure enters the discharge passage 32 through the upper cavity 20 of the valve cap 2, pushes the steel ball 16 downwards, and enters the valve cavity 10 through the guide hole 30 of the upper valve rod 4, so that the pressure difference between the inlet and the outlet is balanced, and the siphon is prevented.

The invention has been described with reference to a preferred embodiment, to which the above mentioned examples do not limit the invention, and from reading the present description a person skilled in the art will be able to conceive of numerous modifications and variations to the structure, any obvious alternative being within the scope of protection of the invention without departing from the inventive concept.

Claims

1. Backpressure check valve, its characterized in that includes valve body (1), valve cap (2), goes up valve stem (3), lower valve rod (4), disk seat (5), spring (9), adjusting screw (11), valve body (1) has entrance way and exit channel and communicates entrance way and exit channel's valve pocket, valve cap (2) are connected on valve body (1), spring (9) set up in last cavity (20) of valve cap (2), adjusting screw (11) set up above spring (9), the axial is adjusted the decrement of spring (9), it sets up in lower seal chamber (22) of valve cap (2) to go up valve stem (3), lower valve rod (4) connect movably go up valve stem (3) lower extreme, go up valve stem (3) and lower valve stem (4) axial separable, valve seat (5) set up down on (4), when the valve is closed, the valve seat (5) and the end of the inlet passage form sealing surfaces (52,54), and the ratio of the projected area of any horizontal section on the sealing surface (52.54) of the valve seat (5) to the projected area of the horizontal section of the lower sealing cavity (22) of the valve cap (2) is 0.6-1.4.

2. The back pressure check valve according to claim 1, characterized in that the ratio of the projected area of any one horizontal section on the sealing surface (52.54) of the valve seat (5) to the projected area of the horizontal section of the lower seal cavity (22) of the bonnet (2) is 0.95 to 1.05.

3. The back pressure check valve according to claim 2, characterized in that the outer wall of the upper valve stem (3) is provided with an annular groove (34), and a sealing member (14) is arranged in the annular groove (34).

4. The back pressure check valve according to claim 3, characterized in that a limit shoulder (26) is provided between the upper cavity (20) and the lower seal cavity (22) of the bonnet (2).

5. The back pressure check valve according to claim 4, characterized in that the lower end of the upper valve stem (3) is provided with a guide hole (30), the upper end of the lower valve stem (4) is provided with a protrusion (42), and the protrusion (42) is in clearance fit with the guide hole (30).

6. The back pressure check valve according to claim 5, characterized in that a weak spring (7) is provided in the pilot hole (30).

7. The back pressure check valve according to claim 6, characterized in that the upper end of the upper valve rod (3) is provided with a discharge passage (32) communicated with the guide hole (30), the outlet of the discharge passage (32) is communicated with the upper center hole (20) of the valve cap (2), the outlet end is provided with a steel ball (16), and an elastic element (17) is arranged below the steel ball (16).

8. The back pressure check valve according to any of claims 1-7, characterized in that a locking screw (12) is provided on the bonnet (2), the locking screw (12) being located above the adjusting screw (11).