JPS6347575A - Check valve - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to an improved check valve capable of preventing undesired fluid leakage even under low fluid pressures, and more particularly to The present invention relates to a valve body that supports an annular seal that deflects when it comes into contact with the valve body.

(Technical uses of the invention and its problems) Check valves are generally well known. A one-way valve is a device that allows fluid to pass in one direction and prevents fluid from passing in the opposite direction. An ideal check piece would allow passage of fluid in one direction, but would block any undesired passage of fluid in the opposite direction. ! lI! ! Type inversion 11: The valve has a larger valve chamber that accommodates a movable valve body, such as a piston ball, and a valve seat provided at one end of the valve chamber. The flow of fluid in the opposite direction pushes the valve body to one side and brings the valve body into close contact with the valve seat, thereby preventing the flow of fluid in the opposite direction.

In such check valves, in order to prevent the valve body from effectively pressing against the valve seat and creating a close contact with the valve seat, a minimum pressure value is required for the fluid pressure in the opposite direction. is necessary. moreover,
A small amount of flow in the opposite direction may occur before the valve body is biased against the valve seat. A common feature of such check valves is that the higher the fluid pressure of the reverse flow, the better the sealing performance between the valve body and the valve seat. However, many types of check valves have difficulty preventing flow in the opposite direction under low fluid pressures.

A check valve or expansion device used in a refrigeration system is disclosed in U.S. Pat. No. 3.877.2, incorporated herein by reference L'3.
48Q, M3,642.030 and 3,992,8
A summary is disclosed in No. 98. U.S. Patent No. 3.992
．． Figure 2 of No. 898 discloses a check valve to be used in a reversible heat pump system. Such heat pump type check valves allow bidirectional flow, such as allowing multiple fluid flows in one direction and only a controlled suspended flow in the opposite direction. is desirable. In refrigeration systems, it is desirable for check valves to prevent unwanted flow even at low fluid pressures. For example, looking at FIG. 2 of U.S. Pat. It is desirable to prevent backflow around piston 45. Those skilled in the art will appreciate that in many cases, vehicle equipment allows only a controlled flow of fluid to pass through the valve through the control boat, even though the pressures that create the backflow are relatively low.

FIG. 4 shows a typical check valve used in refrigeration systems. This check valve prevents backflow (flow from bottom to top in Figure 4) and allows flow in the opposite direction (flow from top to bottom in Figure 4). In a heat pump system, a control boat may be provided proximal to the piston of FIG. 4 to allow a controlled small amount of reverse flow. As is clear from FIG. 4, the seal that prevents fluid flow in the opposite direction is created by compressing the gasket G in contact with the annular valve seat S of the check valve. That is, the fluid pressure in the opposite direction urges the piston P in the opposite direction (from the bottom to the top). In addition, the gasket G contacts the valve seat S while being compressed. The gasket G is typically a Teflon ring that is placed on the piston P during assembly. There is some non-uniformity in the thickness of this gasket G, and a small amount of incorrect assembly occurs during assembly. If such a condition exists, a small amount of fluid leaks through the gasket in the opposite direction until the fluid pressure becomes high enough to urge and deform the gasket G against the valve seat S./I: do.

FIG. 6 shows typical test results for leaks occurring through the check valve illustrated in FIG. The horizontal axis of FIG. 6 represents the reverse fluid pressure applied to the check valve of FIG. 4, and the vertical axis represents the fluid indexing that occurs through the piston P.

As seen in FIG. 6, little leakage through gasket G occurs under relatively high fluid pressure differentials (eg, 80 psio). However, multiple fluid leaks occur through the gasket G under low fluid pressure. In refrigeration systems, such fluid leaks are undesirable and result in inefficient system operation.

(Objective of the Invention) The above-mentioned problems can generally be solved by the check valve according to the present invention.The check valve of the present application efficiently prevents undesired fluid backflow even under low fluid pressure. With the goal.

To this end, the improved check valve shown herein includes a slidable piston with a deformable seal. The seal is supported so that it flexes when it abuts an annular seat in the check valve. At low fluid pressures, the seal flexes and contacts the valve seat, effectively preventing leakage of fluid around the valve seat. or,
This flexural contact prevents fluid leakage under fluid pressures lower than those required to compress a conventional valve gasket.

(Summary of the Invention) A check valve according to the present invention includes a slidable piston having a tip that fits into a valve seat of the check valve.

The distal end includes an annular circumferential groove, an end on one side of the circumferential groove, and a base on the other side of the circumferential groove. An annular ring or seal is operably received in the circumferential groove, the circumferential groove supporting an inner portion of the seal, and an outer portion of the seal projecting from the circumferential groove to define a seal profile. The seal and piston function cooperatively such that under fluid pressure applied to the valve seat, the outer portion of the seal contacts the valve seat and deflects further toward the base of the tip.

In a preferred embodiment, the distal end of the tip has a frusto-conical shape with an angle of 45° and the base of the tip has an outer surface with an oblique angle of 60° to the axis of the piston. The base of the tip near the seal is recessed inwardly so as not to support the outer portion of the seal.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. The check valve 10 according to the present invention generally includes an elongated and substantially cylindrical main body 12, and is slidably housed inside the main body 12. a piston 14 and a seal 1 attached to the piston 14;
Contains 6. The cylindrical body 12 has a first passage 20 formed in a cylindrical shape and a second passage 22 formed concentrically therewith in the shape of an expanded cylinder.

As can be seen in FIG. 1, the passage 20.22 is delimited by a frusto-conical valve seat 24. The first passage 20 communicates with a plurality of distributor tubes 26, while the second passage 22 has threads for coupling to other parts of the refrigeration system. When the check valve 10 is used in a reversible heat pump type system, the valve 10
functions as an inflation bladder δ when the passageway 22 is connected to a similar inflation bladder d having the same number in the direction opposite to the direction of fluid flow.

The elongated piston 14 is generally cylindrical in shape and has a plurality of longitudinal grooves 30 spaced axially about the circumference of the piston. The piston 14 has a closure body 32 having a substantially conical shape. Further, the piston 14 is connected to the closing body 3
2 is installed inside the passage 22 so as to face the valve seat 24. As shown in FIG. 1, the screw 14 has an elongated tapered restrictor orifice 28 extending coaxially with the piston to permit controlled reverse flow of fluid through the piston. has. However, in other embodiments, orifice 28 is eliminated and a pure one-way flow check valve is contemplated.

The closing body 32 has an annular circumferential groove 34 and this groove 31.
1 and a proximal end 38 on the other side of the circumferential groove 34 . Distal end 36 preferably has a frusto-conical shape, with its outermost surface forming an angle of approximately 45° with respect to the axis of piston 14 (see FIG. 3).

As shown in FIG. 3, a substantially flat support surface 40 is provided on one side of the circumferential groove 34 and is formed in a direction perpendicular to the axis of the piston. The proximal end 38 is "slanted" inwardly to abut the support surface 40 and has an annular frusto-conical shape as shown. are doing. Here, "sloping" means that the outermost sloped portion of the proximal end 38 is retracted axially and inwardly with respect to the extension of the frusto-conical outermost surface of the distal end 36. It means that (3rd
(see figure). As can be seen from FIG. 3, the included angle between the axis 14 of the piston 14 and the outermost slope of the base end 38 is approximately 60.
”.

The sealing means 16 is preferably an annular, compressible, flexible ring of tetrofluoroethylene (Teflon) type material. Seal 16 is made in one piece and has an inner portion 44 and an outer portion 46, as shown in FIG. The support surface 40G has an approximate dimension width complementary to the width of the inner portion 44. Thus, the support surface 40 provides sufficient support for the negative inner portion 44 (near the proximal end 38) of the seal 16. As shown in FIG. 1, outer portion 46 is unsupported in the configuration of groove 34.

In use, the check valve 10 of the present invention has piston 14
The fluid flows in one direction (from top to bottom in the drawing) by passing the fluid around the vertical groove 30 of J'.
. When fluid pressure is applied in the opposite direction (from bottom to top in the drawing), the piston 14 slides to the position shown in FIG. position.

In a preferred embodiment, it is desirable to prevent passage of fluid around the piston when reverse fluid pressure is applied. When fluid pressure in the opposite direction is applied, piston 1
4 slides until the seal 16 engages the valve seat 24 (see FIG. 1). A small, controlled, reverse flow of fluid is allowed through the A-rifice 28. When reverse fluid pressure is applied, the outer portion 46 is biased by the valve seat 24 so that the seal 16 flexes as shown in FIG.

Inner portion 44 is supported by support surface 40 while outer portion 46 is unsupported. This initially causes the seal 16 to flex or bend as shown in FIG. When the fluid pressure in the opposite direction persists, the outer portion /I6 moves toward the proximal end 3
It is bent until it hits the outermost slope of 8. If the fluid pressure in the opposite direction increases further, the Teflon seal 16 will be compressed.

FIG. 4 shows a known check valve. In known examples, it was generally thought that the sealing action produced by the Teflon-filled gasket G hitting the valve seat 24 and being compressed would provide sufficient sealing performance. However, as shown in the comparison diagrams of FIGS. 4 and 6, there is a large difference in sealing performance between the known check valve and the check valve 10 of the present invention. When reverse fluid pressure is applied to a known check valve (FIG. 6), the reverse fluid leakage that occurs through piston P is 212 d at pressures below 60 psig.
exceed. As shown in FIG. 6, under even higher pressures, compression of the Teflon gasket G begins to occur and reverse fluid leakage is significantly reduced.

Under the low fluid pressures encountered in many types of refrigeration systems, including reversible heat pump refrigeration systems, reverse fluid leakage is significant and is associated with a degradation of refrigeration system performance.

In contrast, the backflow that occurs through the present check valve 10 (in the absence of control orifice 28) is nearly non-leakable for all practical adverse fluid pressures.

As shown in FIG. 5, under reverse fluid pressures in excess of 5 to 10 psig, fluid leakage is virtually zero. Thus, even under low reverse fluid pressures, the check valve 10 of the present invention functions to prevent unwanted reverse fluid leakage.

In many applications, fluid pressure in the opposite direction is applied!
,: Sometimes it is desirable to allow a small amount of controlled, reverse flow. For this purpose, the check valve 10 is provided with an elongated control orifice 28 within the piston 14 extending concentrically with the piston 14. The fll lit boat is dimensioned to permit known reverse fluid flow. Preferably, reverse fluid flow occurs through the control orifice 28 rather than between the valve seat 24 and the seal 16. The check valve 10 of the present invention operates to substantially prevent fluid leakage between the valve seat 24 and the seal 16 even under low fluid pressures.

It is also often desirable to prevent reverse fluid flow through piston 14. For example, it may be desirable to use check valve 10 as a simple one-way flow check valve. In this case orifice 28 is removed. Similarly, due to design requirements, the check valve 10 is a simple one-way flow device that connects a reverse flow path that is provided in parallel to bypass the check valve 10. unknown. In any case, according to the invention, the valve seat 2; 4 and the seal 16
Unwanted leakage between the two can be prevented.

〔Effect of the invention〕

In the check valve according to the present invention, b
Since the seal contacts the valve seat at an angle of 11/ν, leakage of fluid around the valve seat can be effectively prevented. or,
This flexural contact allows fluid leakage to be prevented even under fluid pressures lower than the sag and force required to compress a conventional valve gasket.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a check valve according to the present invention; FIG. 2 is omitted, L
FIG. 3 is an enlarged partial sectional view of a portion of a piston according to the invention; FIG. Figure 5 is a top view of a known check valve; Figure 5 is a dimensional graph showing the amount of fluid leaking through the check valve of the present invention under various fluid pressures; Figure 6 is similar to Figure 5. 4 is a graph illustrating the fluid excavation that occurs through the known check valve shown in FIG. 4 under various fluid pressures.

Claims (16)

[Claims] 1. A check valve for sealing a valve seat disposed at an end of a passage, the check valve being slidably housed inside the passage opposite to the valve seat, and having a circumferential groove and a circumferential groove. a closure comprising a distal end on one side of the circumferential groove and a proximal end having a seal support surface on the other side of the circumferential groove and sloped radially and outwardly from the groove; a sealing means received within said circumferential groove and having an inner portion and an outer portion, said circumferential groove supporting said inner portion of the sealing means and an outer portion of the sealing means; extend beyond the circumferential groove, and the distal and proximal ends are such that the distal end does not contact the valve seat when the piston is moved toward the valve seat, and the proximal end the seal bearing surface of the valve is non-linear so as to converge outwardly relative to the valve seat, and the seal means and piston means are disposed within the passageway such that a relatively low fluid pressure is applied to the valve seat. deflecting the outer portion toward the proximal end when applied to the valve seat, creating an initial deflection seal between the seat and the outer portion of the sealing means when the sealing means contacts the valve seat; A check valve characterized in that it is operable to cause compression of an outer portion of the sealing means between the valve seat and the proximal end when fluid pressure against the valve seat increases. 2. 2. The check valve according to claim 1, wherein the valve seat and the base end of the closing body have a substantially truncated conical shape. 3. The sealing means includes an annular ring having a predetermined width along the annular cross section, and the groove is formed in an annular shape and has a substantially flat support surface near the proximal end. 3. The check valve according to claim 2, wherein the support surface has a width substantially equal to the predetermined width. 4. 2. The check valve according to claim 1, wherein said end portion has a substantially conical shape. 5. The converse of claim 1, wherein the acute included angle between the valve seat and the axis of the passage is smaller than the included angle between the piston axis and the oblique seal support surface of the base. Stop valve. 6. The distal end portion has a substantially conical shape, and the acute included angle formed between the axis of the piston and the outermost surface of the proximal end portion is approximately equal to the included angle formed between the valve seat surface and the axis of the passage. The check valve according to item 1. 7. 9. The check valve according to claim 8, wherein the included angle between the axis of the piston and the inclined surface of the base end is about 45 degrees. 8. 3. The check valve according to claim 2, wherein the acute included angle formed by the axis of the piston and the outermost slope of the base end is approximately 60 degrees. 9. 4. The check valve according to claim 3, wherein the annular ring is substantially flat and compressible, and is made of tetrafluoroethylene. 10. Claim 1, characterized in that the piston means is provided to be freely floating and slidable within the passageway in response to the biasing force of the fluid toward or away from the valve seat. The check valve according to item 1. 11. A first passage and a second passage are provided such that the first passage is arranged circumferentially in line with the expanded second passage, and the first passage is provided between the first passage and the second passage. an annular frusto-conical valve seat; and a free-floating piston received within the second passage for sliding movement toward and away from the valve seat when fluid pressure is applied thereto. In a check valve for a refrigeration system in which the piston has a substantially conical closing body housed near the valve seat, an annular circumferential groove is formed in the closing body, and a flexible groove is formed in the circumferential groove. A flexible tetrafluoroethylene ring is attached, and a proximal end of the closure near the ring is inclined inwardly and radially outwardly at a predetermined angle; the outermost region of the ring so as to bring the outermost region of the ring into flexible sealing engagement with the valve seat when a relatively low fluid pressure is applied to the valve seat and the piston is biased against the valve seat; a region unsupported in the circumferential groove, and further comprising compressing an outermost region of the ring between the valve seat and the proximal end into sealing engagement as fluid pressure against the valve seat increases. A check valve for refrigeration systems with special features. 12. Claims: The closure body has a generally conically shaped distal end having an angle of about 45 degrees, and the proximal end defines an inwardly sloping outer surface. The check valve according to item 10. 13. 12. The check valve according to claim 11, wherein the closing body has a substantially frustoconical shape. 14. 12. The check valve according to claim 11, wherein said piston is provided with a vertical rib along its outermost circumference. 15. The outer surface of the base end has a substantially truncated conical shape,
12. The check valve of claim 11, wherein the check valve forms an angle of approximately 60 DEG with respect to the axis of the piston. 16. an elongated valve seat disposed between a relatively narrow first passageway and a relatively wide second passageway, the valve seat forming a predetermined acute angle with a centerline of the second passageway; a housing and an elongated free-floating piston slidably disposed within the passageway for movement toward or away from the valve seat in response to the pressure of a fluid biased toward or away from the valve seat. a frusto-conically shaped distal end oriented toward the first passageway and sized to be received within the first passageway; and a circumference formed on the piston proximate the distal end; a groove, and a piston having an inclined surface forming an angle with the axis of the piston that is larger than a predetermined acute angle of the valve seat, and a base end portion provided near the groove; an annular, generally non-elastomeric, tetrafluoroethylene seal received in a circumferential groove and having an inner portion and an outer portion, the seal being compressed when the piston is urged by fluid pressure against the valve seat. the groove is provided so that the circumferential groove supports the inner portion but not the outer portion so as to give an initial deflection to the outer portion immediately after the outer portion contacts the valve seat; A check valve further characterized in that an outer portion of the seal between the valve seat and the base is compressed as fluid pressure against the valve seat increases.