WO2014072979A1

WO2014072979A1 - Check valve

Info

Publication number: WO2014072979A1
Application number: PCT/IL2013/050918
Authority: WO
Inventors: Avraham Zakay
Original assignee: S P C Tech Ltd
Current assignee: S P C Tech Ltd
Priority date: 2012-11-08
Filing date: 2013-11-07
Publication date: 2014-05-15
Anticipated expiration: 2015-05-08

Abstract

A check valve is provided comprising: a housing (11) having an inlet (12a), an outlet (12b), a primary port (32) and a successive port (34) and an intermediate port (38) defined between the primary port and the outlet. The check valve further comprises a plunger (20) disposed between the inlet and the outlet and including a first portion (22a) having a first cross sectional area (23a) configured to engage the primary port, and a second portion (22b) having a second cross sectional area (23b) configured to engage the successive port. The second cross sectional area is larger than the first cross sectional area. The plunger (20) is selectively movable between a closed position in which the first portion (22a) engages the primary port (32) thereby precluding fluid flow therethrough, an intermediate position in which the second portion (22b) engages the successive port (34) and fluid flow is permitted through the primary port (32) and through the intermediate port (38), and an open position in which fluid flow is permitted through the primary port (32) and through the successive port (34).

Description

CHECK VALVE

TECHNOLOGICAL FIELD

The presently disclosed subject matter relates to a check valve in general, and in particular to a check valve for fluid supply lines.

BACKGROUND

Check valve is a device for automatically limiting flow in a piping system to a single direction, and is also known as a non-return valve. Check valves generally include a housing having an inlet for fluid to enter the housing and an outlet for fluid to exit the housing and a selective stop mechanism inside the housing. There are various types of check valves used in a wide variety of applications and are commonly used in a household water pipelines.

An example of a check valve is an in-line check valve which has a spring configured to push a plunger disposed in the housing. The plunger is pushed to an open position when the pressure at the inlet is substantially higher than the pressure at the outlet. Depending on the force of the spring the pressure difference between the inlet and outlet is such which can overcome the spring tension, and is called the 'cracking pressure'. When the pressure difference between the two sides of the valve is below the cracking pressure, the spring urges the plunger back to the closed position of the valve so as to prevent back-flow in the pipe. Typically the check valve is designed to operate at a specific cracking pressure.

The check valve can be used for protection of any item of equipment that can be affected by reverse flow, such as flowmeters, strainers and control valves. GENERAL DESCRIPTION

According to an aspect of the presently disclosed subject matter there is provided a check valve comprising: a housing having an inlet, an outlet, a primary port and a successive port and an intermediate port defined between the primary port and the outlet. The check valve further comprising a plunger disposed between the inlet and the outlet and including a first portion having a first cross sectional area configured to engage the primary port, and a second portion having a second cross sectional area configured to engage the successive port. The second cross sectional area is larger than the first cross sectional area. The plunger is selectively movable between a closed position in which the first portion engages the primary port thereby precluding fluid flow therethrough, an intermediate position in which the second portion engages the successive port and fluid flow is permitted through the primary port and through the intermediate port, and an open position in which fluid flow is permitted through the primary port and through the successive port.

The housing can define a volume having a cross sectional area larger than the cross sectional area of the inlet, wherein the successive port can be defined in the volume and the primary port is defined in the inlet.

The inlet can be configured in an inlet segment of the housing and the outlet can be configured in an outlet segment of the housing wherein the inlet segment and the outlet segment are provided with coupling means for coupling to one another. The inner diameter of the outlet segment can be larger than the inner diameter of the inlet segment and wherein the successive port can be defined by an inner surface of the inlet segment.The inlet segment can include an elongated portion defined on an inner surface thereof, such that in the intermediate position when the plunger is displaced toward the outlet the second portion maintains a sealing engagement with the the inner surface of the inlet segment and the successive port remains closed.

The first portion can be an elongated portion configured to be extended inside the primary port. The first portion can be provided with a seal configured to bear against a wall of the primary port.

The second portion of the plunger can include a resilient member mounted about the periphery thereof, and configured to sealingly engage an inner surface of the housing. In the open position the resilient member can be disposed outside the successive port thereby allowing fluid flow therethrough. The check valve can further comprise a retaining member configured for securing the resilient member on the second portion.

The intermediate port can be an aperture defined in the resilient member. Alternatively, the intermediate port can be a depression defined in the resilient member defining a flow path between the primary port and the outlet.

Alternatively, the intermediate port can include a throughgoing bore defined in the plunger allowing fluid flow from the primary port towards the outlet in the intermediate position. According to another example, the intermediate port is a bypass channel defined in the housing allowing fluid flow from the primary port towards the outlet in the intermediate position.

The plunger can be a cone shape plunger and can be spring biased. The spring force of the spring can be configured such that the head loss of the plunger in the intermediate position is high while the head loss of the plunger in the open position is low.

The size of the intermediate port can be such which allows pressure equalization between the intermediate port and the outlet only under leak conditions.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to better understand the subject matter that is disclosed herein and to exemplify how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

Fig. 1 is a perspective view of the check valve in accordance with one example of the presently discloses subject matter;

Fig. 2 is an exploded perspective view of the valve of Fig. 1;

Fig. 3A is a side sectional view of the valve of Fig. 1 taken along lines A- A, in the closed position;

Fig. 3B is a side sectional view of the valve of Fig. 1 taken along lines A-A, in the intermediate position;

Fig. 3C is a side sectional view of the valve of Fig. 1 taken along lines A-A, in the open position;

Fig. 4A is a partially exploded perspective view of the valve of Fig. 1 in the closed position; Fig. 4B is a partially exploded perspective view of the valve of Fig. 1 in the intermediate position;

Fig. 4C is a partially exploded perspective view of the valve of Fig. 1 in the open position;

DETAILED DESCRIPTION OF EMBODIMENTS

In Figs. 1 and 2 there is illustrated a check valve 10 according to an example of the presently discloses subject matter. The check valve 10 includes a housing 11, here illustrated as divided to two components, an inlet segment 11a being provide with an inlet 12a and an outlet segment lib which is provided with an outlet 12b. The inlet segment 11a is formed with a screw thread 14a defined on an external surface thereof and configured to be fastened to a corresponding screw thread 14b defined on an internal surface of the outlet segment lib. The inlet and outlet segments 11a, lib are configured for sealable engagement with one another such that when fastened to one another the valve can operate without leaks of the fluids therein. According to the illustrated example, an O-ring 16 is disposed on the screw thread 14a, of the inlet segment 11a, configured to engage the edge of the corresponding screw thread 14b of the outlet segment lib.

The inlet 12a can be configured to be coupled to a source of fluid, such as a water supply company or a main supply line, while the outlet 12b can be coupled to a consumer pipeline, such as apartment main, or a faucet. According to an example, the inlet 12a and the outlet 12b are provided with a screw thread 13 for coupling to other pipe elements. It is appreciated that other coupling means can be provided for coupling the valve 10 to other pipe elements.

As shown in Figs. 3A to 3C, the housing 11 includes a volume 18 defined between the inlet 12a and the outlet 12b for holding a plunger 20 therein. The volume 18 is defined by both the inlet segment 11a and the outlet segment lib and at least a portion of which includes a diameter which is larger than that of the inlet 12a. The inner diameter of the volume in the outlet segment lib which is defined by the inner surface 15b is slightly larger than the inner diameter of the inlet segment 11a, which is defined by the inner surface 15a. The housing 11 defines a primary port 32 which can be disposed between the inlet 12a and the volume 18, and a successive port 34 defined by an inner surface 15a of the inlet segment 11a. The successive port 34 is defined inside the volume 18 for example, by the inner surface 15a of the inlet segment 11a. According to the illustrated example the volume 18 has a cross sectional area larger than that of the inlet 12a and hence the primary port 32 includes a cross sectional area smaller than that of the successive port 34.

As can best be seen in Fig. 2, the check valve 10 further includes a plunger 20 disposed in the volume 18 between the inlet 12a and the outlet 12b. The plunger 20 includes a first portion 22a having a first cross sectional area 23a configured to engage the primary port 32, and a second portion 22b having a second cross sectional area 23b configured to engage the successive port 34. The second cross sectional area 23b is larger than the first cross sectional area 23a, and thus the first portion 22a is configured to engage the wall of the primary port 32 thereby precluding fluid transfer thethrough, and the second portion 22b is configured to engage the successive port 34 thereby precluding fluid transfer therethrough.

The second portion 22b of the plunger 20 is successively disposed with respect to the first portion 22a thereof, thus the second portion can be configured to preclude transfer of fluid through the successive port 34 even in case where the first portion does not engage the primary port 32.

According to the illustrated example, the plunger 20 is of a cone shape, such which the narrow portion thereof defines the first portion 22a and is configured to sealingly engage the primary port 32, and the wide portion thereof defines the second portion 22b of the plunger 20 and is configured to sealingly engage the successive port 34. The first portion 22a of the plunger 20, according to this example, can be made as an elongated portion, such that it can be extended inside the primary port 32 thereby ensuring sealing engagement between the plunger and the wall of the primary port 32.

In addition, the inner surface 15a of the inlet segment 11a can include an elongated portion, such that even when the plunger 20 is displaced from the closed position toward the outlet (hereinafter described as an 'intermediate position') the second portion 22b thereof maintains a sealing engagement with the inner surface 15a of the inlet segment 11a and the successive port 34 remains closed, until the plunger reaches the inner surface 15b of the outlet segment lib.

The first portion 22a of the plunger 20 can include a seal 25 configured to bear against a shoulder portion defined between the wall of the primary port 32 and an inside wall of the volume 18, when the plunger is in its closed position. The seal 25 is configured to allow fluid to be transferred thereabout, when the plunger is displaced to the open position, thereby causing the seal to disengage the wall of the primary port.

The second portion 22b can include a resilient member 27 mounted about the periphery thereof, and configured to sealingly engage the inner surface 15a of the inlet segment 11a. The resilient member 27 is configured to allow maintaining sealing engagement with the inner surface 15a even when the plunger 20 is displaced into the intermediate position, until reaching the area of the volume having a larger diameter defined by the inner surface 15b of the outlet segment lib, bringing the valve 10 to the open position thereof. According to an example, the resilient member 27 is mounted on the second portion 22b by means of a retaining member 27a configured to hold the resilient member in place.

The plunger 20 is configured with an arm 24 configured to slide within a cylindrical guide 26 which can be coupled to the outlet housing for example by one or more lateral ribs 28a. The arm 24 and the cylindrical guide 26 maintain the plunger 20 in place, such that it can be displaced between an open position, an intermediate position, and a closed position of the valve 10 as described in detail herein below. The arm 24 and the cylindrical guide 26, thus, precludes side movements of the plunger 20 within the volume 18 such which may allow fluid to leak through the primary port 32 or the successive port 34 even when in the closed position.

The plunger 20 is further provided with a spring 28 or any other return mechanism configured to urge the plunger back to the closed position thereof, wherein the first portion 22a engages the primary port 32. The spring 28 can be mounted over the cylindrical guide 26 and can be configured to bear against lateral ribs 28a on one side thereof and on a portion of the plunger 20 on the other side thereof.

The spring 28 according to this example is configured to urge the seal 28 onto the shoulder portion defined between the wall of the primary port 32 and an inside wall of the volume 18, when the plunger is in the closed position. The spring 28 or any other return mechanism can be configured such that the plunger 20 is displaced only in response to pressure exceeding a predetermined threshold. For example, the spring coefficient can be such that only pressure of a predetermined degree applied on the plunger 20 can overcome the force of the spring 28, so as to displace the plunger to the intermediate position or to the open position. It is appreciated that since the cross sectional area of the plunger 20 varies between the first portion 22a and the second portion 22b, the pressure requires to displace the plunger can vary depending on which portion of the plunger the pressure is applied. That is to say, the force of the spring 28 causes a head loss, which can be defined here as the amount of pressure gradient force which is required when moving the plunger 20 against the force of the spring. Thus, pressure gradient required can be defined as the ratio of force to the area over which that force is distributed namely:

f

AP =—

A

where is F_k is the force applied by the spring 28, and A is the cross sectional area over which the force is applied. As known, the pressure allows the movement of the plunger 20 only when there is a positive pressure gradient in the direction of the movement, between the inlet 12a and the outlet 12b, namely the pressure at the outlet is lower than that in the inlet. Thus, AP , which designates the difference between the pressure at the inlet 12a and the pressure at the outlet 12b, defines the amount of pressure gradient force which is required for overcoming the force of the spring 28.

It is thus appreciated that since the cross sectional area of the plunger 20 varies, the amount of pressure lost when overcoming the force of the spring 28 varies as well. Accordingly, as described in detail below, since the cross sectional area 23a of the first portion 22a of the plunger 20 is smaller than the cross sectional area 23b of the second portion 22b of the plunger, the amount of pressure lost over the plunger when applied on the first portion 22a is larger than when the pressure is applied on the second portion 22b.

The valve further includes an intermediate port 38 defined between the primary port 32 and the outlet 12b. The intermediate port 38 is configured to allow relatively small fluid flow therethrough, when the primary port 32 is open, even while the successive port 34 is closed. According to an example, the intermediate port 38 can be an aperture defined in the resilient member 27 or a depression 29 in the resilient member 27 allowing fluid flow between the primary port 32 and the outlet 12b.

Alternatively, the intermediate port 38 can be defined as throughgoing bore in the plunger defined such to allow fluid flow from the primary port 32 towards the outlet 12b even when the successive port 34 is closed. According to a further example, the intermediate port 38 can be a bypass channel defined in the housing 11 allowing fluid flow from the primary port towards 32 the outlet 12b even when the successive port 34 is closed.

The plunger 20, thus, is selectively movable between a closed position, an intermediate position, and an open position. In the closed position the first portion 22a engages the primary port 32 thereby precluding fluid flow therethrough. In the intermediate position the second portion 22b engages the successive port 34 and while fluid flow is permitted through the primary port 32 and through the intermediate port 38. In the open position the plunger is displaced away from both the primary port and the successive port 34 and fluid flow is permitted therethrough towards the outlet 12b.

Reference is now made to Figs. 3A and 4A, when pressure at the outlet 12a is substantially equal to that of the inlet 12a, the pressure gradient across the valve is substantially zero, thus no force is applied on the plunger 20 beside the force exerted by the spring 28, urging the plunger into the primary port 32. In this position the seal 25 abuts the wall of the primary port 32 thereby precluding any fluids from flowing from the inlet 12a towards the outlet 12b.

As shown in Figs. 3B and 4B, when pressure at the outlet 12b slightly drops, the pressure gradient across the valve becomes positive. This can be for example, in case the valve 10 is used in a water pipeline, in response to a minor fluid consumption, such as a leaking faucet. Since the pressure exerted on the plunger 20 form the inlet side is higher than the pressure exerted thereon from the outlet side, the plunger tends to be displaced in the direction of the pressure gradient, i.e towards the outlet 12b. However, the spring 28 maintains the plunger 20 in place, until the force generated by the pressure gradient is stronger than the force of the spring. At this point, the pressure gradient applies a force on the cross sectional area 23a of the first portion 22a, counter to the force of the spring 28. The amount of pressure required in order to overcome the force of the spring at the closed position can be expressed as: f

AP = ^-

A

where Α is the cross sectional area 23a of the first portion 22a.

Thus, the plunger is urged to slightly move towards the outlet 12b, thereby the first portion 22a disengages the primary port 32 allowing fluid flow therethrough. Since the successive port 34 is defined by the inner surface 15a which extends along a predetermined length inside the volume 18, the resilient member 27 maintains a sealing engagement therewith even when the plunger 20 is slightly shifted towards the outlet 12b. Thus, in this intermediate position fluid flow through the successive port 34 is still precluded, and the fluid flow towards the outlet is allowed only through the intermediate port 38, i.e. through the depression 29 in the resilient member 27.

It is appreciated that the fluid consumption in the intermediate position is not large enough and the required fluid can be provided through the intermediate port 38. It is further noted that the pressure at the outlet 12b at this stage is substantially the same as the pressure at the intermediate port 38. The difference between the pressure at the inlet 12a and the pressure at the intermediate port 38 generates a pressure gradient force which provides a counterforce applied on the cross sectional area 23a of the first portion 22a, urging the plunger 20 against the spring 28. Thus, no further force is applied on the second portion 22b of the plunger 20, and the plunger 20 can remain in place while the first portion 22a thereof is disengaged from the primary port 32, while the second portion 22b thereof is still engaged with the successive port 34.

Referring now to Figs. 3C and 4C, as the fluid consumption increases, for example as a faucet is opened, the pressure at the outlet 12b drops and a pressure gradient across the valve 10 is again formed. This time, due to the relatively large fluid consumption, the pressure at the outlet 12a is significantly lower than that at the intermediate port 38 since the depression 29 in the resilient member 27 is not large enough to allow for pressure equalizing to occur therethrough. Thus, at this stage a pressure gradient force is acting on the second portion 22b of the plunger 20, urging in the illustrated example, the resilient member 27 towards the outlet 12b, bringing the plunger 20 to the open position thereof. As the resilient member 27 reaches the inner surface 15b of the outlet segment lib, which has a diameter slightly larger than that of the inlet segment 11a, the resilient member 27 disengages the successive port 34 and fluid flow is allowed therethrough and further through the gap between the resilient member and the inner surface 15b of the outlet segment lib. At this position, pressure equalizing between the outlet 12b and the successive port 34 as well as the primary port 32 can occur.

It is appreciated that a complete pressure equalizing cannot occur as some of the pressure gradient force is used as a counterforce to the force of the spring 28. The amount of pressure gradient required in order to overcome the force of the spring in the intermediate position can be expressed as:

f

AP = ^- where A₂ is the cross sectional area 23b of the second portion 22b. Thus, since A₂ is larger than Α , the amount of pressure gradient required to overcome the force of the spring 28 in the intermediate position is lower than that which is required in the closed position. This way, a spring having a high spring force can be used, so as to maintain the plunger in the closed position until a sufficient pressure gradient is built across the valve, such which can act on the first portion having a relatively small cross sectional area. When there is a normal fluid consumption, however, during which it is desirable to minimize the head loss of the valve such that the pressure provided at the outlet 12b is close to that of the inlet 12a, the force of spring 28 is countered by pressure applied on the second portion 22b having a relatively larger cross sectional area. Thus, reducing the amount of pressure required for overcoming the spring force.

It is appreciated that the plunger 20 can remain in this position so long as the pressure gradient across the valve 10 is maintained. Once fluid consumption is decreased or completely stops, the pressure at the outlet increase and the pressure gradient is no longer high enough to overcome the spring force, and the spring urges the plunger 20 back towards the inlet 12a to engage the successive port 34 and the primary port 32.

The plunger 20 and the spring 28 can be configured with the cross sectional areas 23a and 23b of the first and second portions 22a, 22b respectively, in accordance with the desired threshold for opening the valve 10, while minimizing the amount of head loss while in the open position. It is appreciated that the plunger 20 having two portions each having a cross sectional area can be configured in any shape or form. Those skilled in the art to which the presently disclosed subject matter pertains will readily appreciate that numerous changes, variations, and modifications can be made without departing from the scope of the invention, mutatis mutandis.

Claims

CLAIMS:

1. A check valve comprising:

a housing having an inlet, an outlet, a primary port and a successive port and an intermediate port defined between said primary port and said outlet;

a plunger disposed between said inlet and said outlet and including a first portion having a first cross sectional area configured to engage the primary port, and a second portion having a second cross sectional area configured to engage the successive port wherein said second cross sectional area is larger than the first cross sectional area; and wherein said plunger is selectively movable between a closed position in which said first portion engages said primary port thereby precluding fluid flow therethrough, an intermediate position in which said second portion engages said successive port and fluid flow is permitted through said primary port and through said intermediate port, and an open position in which fluid flow is permitted through said primary port and through said successive port.

2. The check valve of Claim 1 wherein said housing defines a volume having a cross sectional area larger than the cross sectional area of said inlet, wherein said successive port is defined in said volume and said primary port is defined in said inlet.

3. The check valve according to any one of the previous claims wherein said inlet is configured in an inlet segment of said housing and said outlet is configured in an outlet segment of said housing wherein said inlet segment and said outlet segment are provided with coupling means for coupling to one another.

4. The check valve according to claim 3 wherein the inner diameter of said outlet segment is larger than the inner diameter of the inlet segment and wherein said successive port is defined by an inner surface of said inlet segment.

5. The check valve according to claim 4 wherein said inlet segment includes an elongated portion defined on an inner surface thereof, such that in said intermediate position when said plunger is displaced toward said outlet said second portion maintains a sealing engagement with said the inner surface of said inlet segment and said successive port remains closed.

6. The check valve according to any one of the previous claims wherein said first portion is an elongated portion configured to be extended inside said primary port.

7. The check valve according to any one of the previous claims wherein said first portion is provided with a seal configured to bear against a wall of said primary port.

8. The check valve according to any one of the previous claims wherein said plunger is a cone shape plunger.

5 9. The check valve of according to any one of the previous claims wherein said second portion of said plunger includes a resilient member mounted about the periphery thereof, and configured to sealingly engage an inner surface of said housing.

10. The check valve of according to claim 9 wherein in said open position said resilient member is disposed outside said successive port thereby allowing fluid flow

10 therethrough.

11. The check valve of according to any one of claims 9 and 10 further comprising a retaining member configured for securing said resilient member on said second portion.

12. The check valve of according to claim 9 wherein said intermediate port is an aperture defined in said resilient member.

15 13. The check valve of according to claim 9 wherein said intermediate port is a depression defined in said resilient member defining a flow path between said primary port and said outlet.

14. The check valve of according to any one of claims 1 to 11 wherein said intermediate port includes a throughgoing bore defined in said plunger allowing fluid

20 flow from said primary port towards said outlet in said intermediate position.

15. The check valve of according to any one of claims 1 to 11 wherein said intermediate port is a bypass channel defined in said housing allowing fluid flow from said primary port towards said outlet in said intermediate position.

16. The check valve of according to any one of the previous claims wherein said 25 plunger is spring biased.

17. The check valve of according to claim 16 wherein the plunger includes a spring and the spring force of said spring is configured such that the head loss of said plunger in said intermediate position is high while the head loss of said plunger in said open position is low.

30 18. The check valve of according to any one of the previous claims wherein the size of said intermediate port is such which allows pressure equalization between said intermediate port and said outlet only under leak conditions.