Pressure reducing valve

Abstract

The pressure reducing valve includes a valve body defining an inlet, an outlet, a chamber, and a flow path from the inlet through the chamber to the outlet. A poppet within the chamber is movable relative to a valve seat over a stroke distance between an open position and a closed position for flow through the flow path. The poppet is in a default open position and has a head end, a shank end, and a gland circumferentially disposed near the shank end. A non-slip seal is disposed within the chamber between the gland and the valve body to seal the poppet against the valve body. The non-slip seal elastically deforms as the poppet moves over the stroke distance. The elastic deformation provides elastic potential energy that acts to bias the poppet against movement.

Description

[Technical Field]

[0001] (Government Rights Statement) The inventions described herein were made during the performance of development under NASA Contract 80JSC021DA020 and are subject to the provisions of Section 20135 of the National Aeronautics and Space Act (51 U.S.C. § 20135). [Background technology]

[0002] Pressure-reducing valves (PRVs) are designed to reduce the pressure of an input fluid to a level required by downstream components using the fluid. Pressure-reducing valves contain a poppet that is movable relative to a valve seat to regulate the flow past the poppet. Pressure feedback across the poppet, in combination with a spring, controls the movement of the poppet and the size of the valve opening for fluid flow. For example, relatively high pressure at the outlet of the pressure-reducing valve is fed back to push the poppet toward a more closed position, reducing flow and lowering pressure. Relatively low pressure at the outlet of the pressure-reducing valve allows the poppet to move toward a more open position, increasing flow and therefore pressure. In this way, pressure-reducing valves self-adjust to fluctuations in outlet pressure. Summary of the Invention [Means for solving the problem]

[0003] A pressure reducing valve according to one example of the present disclosure includes a valve body defining an inlet, an outlet, a chamber, and a flow path from the inlet through the chamber to the outlet. A poppet and a valve seat are disposed within the chamber. The poppet is movable relative to the valve seat over a stroke distance between an open position and a closed position for flow through the flow path. The poppet is in the open position by default. The poppet has a head end, a shank end, and a gland disposed circumferentially near the shank end. A non-slip seal is disposed within the chamber between the gland and the valve body to seal the poppet against the valve body. The non-slip seal elastically deforms as the poppet moves over the stroke distance. The elastic deformation provides elastic potential energy that acts to bias the poppet against movement.

[0004] In a further embodiment of any of the preceding embodiments, the poppet has a head with a diameter D, and the ratio of diameter D to stroke distance is between 625:1 and 200:1.

[0005] In a further embodiment of any of the preceding embodiments, the poppet is pressure actuated.

[0006] In a further embodiment of any of the preceding embodiments, the anti-slip seal is an elastomeric O-ring.

[0007] In a further embodiment of any of the preceding embodiments, the stroke distance is 1 to 3 mils (thousandths of an inch).

[0008] A pressure reducing valve according to one example of the present disclosure includes a valve body defining an inlet, an outlet, a chamber, and a flow path from the inlet through the chamber to the outlet. The poppet has a head end, a shank end, and a gland circumferentially disposed near the shank end. A valve seat is disposed within the chamber. The poppet is movable relative to the valve seat over a stroke distance between an open position and a closed position for flow through the flow path. A second spring biases the poppet to an open position against the first spring by default. A piston is adjacent to the first spring. The first spring acts on the piston to move the poppet. The piston defines a plenum, and a pressure tap connects the outlet to the plenum. Outlet pressure functions as feedback to the piston via the pressure tap. The pressure acts on the piston against the first spring, thereby regulating the movement of the poppet. A non-slip seal is disposed between the gland and the valve body. The non-slip seal elastically deforms as the poppet moves over the stroke distance. The elastic deformation provides elastic potential energy that acts to bias the poppet against movement.

[0009] In a further embodiment of any of the preceding embodiments, the head abuts the valve seat when in the closed position, the head has a diameter D, and the ratio of the diameter D to the stroke distance is between 625:1 and 200:1.

[0010] In a further embodiment of any of the preceding embodiments, the head has a head diameter and the chamber diameter of the chamber in the non-slip seal is greater than the head diameter.

[0011] In a further embodiment of any of the preceding embodiments, the anti-slip seal is an elastomeric O-ring.

[0012] In a further embodiment of any of the preceding embodiments, the stroke distance is 1 to 3 mils (thousandths of an inch).

[0013] In a further embodiment of any of the preceding embodiments, the first spring is a Belleville spring and the second spring is a coil spring.

[0014] In a further embodiment of any of the preceding embodiments, the stroke distance is 1 to 3 mils (thousandths of an inch).

[0015] In a further embodiment of any of the preceding embodiments, the anti-slip seal is anti-slip along the valve body within the chamber over the stroke distance to avoid step shifts in pressure due to slippage.

[0016] A further embodiment of any of the preceding embodiments includes an additional anti-slip seal on the piston.

[0017] The present disclosure may include one or more of the individual features disclosed above and / or below, either alone or in any combination thereof.

[0018] The various features and advantages of the present disclosure will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 10 is a diagram illustrating an example of a pressure reducing valve. [Figure 2] FIG. 10 is a diagram showing an elastically deformed anti-slip seal. DETAILED DESCRIPTION OF THE INVENTION

[0020] In this disclosure, where appropriate, like reference numerals refer to like elements, and reference numerals increased by 100 or multiples thereof refer to modified elements that are understood to incorporate the same features and advantages as the corresponding elements.

[0021] Disclosed herein is a pressure reducing valve ("PRV"). The examples herein are not limited to the specific designs shown and described. As is evident from the examples, the disclosed pressure reducing valve promotes improved performance. For example, the poppet of a pressure reducing valve is continuously adjusted to maintain a substantially constant output pressure. However, there is variation in the output pressure. One measure of variation can be expressed as the ratio of input pressure to output flow. Due to component tolerances, part-to-part play, and other design factors, this ratio often varies over the pressure range over which the pressure reducing valve operates. Particularly in high-performance applications and other end uses, such variation can degrade system performance or require a more robust design to accommodate the variation. As is evident from the examples herein, the disclosed pressure reducing valve promotes reduced variation and improved performance.

[0022] FIG. 1 illustrates a cross-sectional view through a central axis of an example pressure reducing valve 10 ("PRV 10"), also known as a pressure regulator. Generally, pressure reducing valves 10 function to reduce the pressure of a fluid (liquid or gas) using pressure feedback. For example, pressure reducing valve 10 can accept an incoming fluid at a high pressure and reduce the fluid to a lower, substantially constant outlet pressure. As an example, pressure reducing valve 10 is used in rocket engines to reduce the pressure of gas from a high-pressure gas source to downstream rocket engine components.

[0023] Pressure reducing valve 10 includes a valve body 12 defining an inlet 14a, an outlet 14b, and a chamber 16 connecting inlet 14a and outlet 14b. Together, inlet 14a, chamber 16, and outlet 14b define a flow path through pressure reducing valve 10. In practice, a fluid source, such as a high-pressure gas source, is connected to inlet 14a, and outlet 14b is connected to a downstream component to receive the flow exiting pressure reducing valve 10. Valve body 12 is formed from a metal alloy having strength, chemical resistance, or other properties suitable for the end-use environment of pressure reducing valve 10. By way of example, but not limitation, valve body 12 may be formed from a titanium-based alloy or an aluminum-based alloy.

[0024] A poppet 18 is disposed in the chamber 16. Generally, the poppet 18 has a shank end 18a, a head end 18b, and a gland 18c circumferentially disposed near the shank end 18a. A relatively narrow portion of the shank 18a defines a manifold 20 within the chamber 16 for receiving fluid from the inlet 14a.

[0025] The poppet head 18b abuts a valve seat 22 having a gap 22a through which the poppet 18 passes. The diameter of the poppet head 18b is larger than the gap 22a and is movable such that movement of the poppet 18 changes the gap between the head 18b and the valve seat 22, thereby regulating flow through the flow passage. The poppet 18 is movable through an infinite number of positions between a fully closed position against the valve seat 22 and a maximum open position to which the poppet 18 can move within the valve body 12. The amount the head 18b moves from the fully closed position to the maximum open position is the stroke distance. In one example, the stroke distance of the poppet 18 is about 1 mil to about 5 mils (25.4 micrometers to 127 micrometers), such as 1 mil to 3 mils (76.2 micrometers) or about 2 mils (50.8 micrometers).

[0026] A first spring 24 is located adjacent one end of the poppet 18 and a second spring 26 is located at the other end adjacent the head 18b of the poppet 18. The first spring 24 is stronger than the second spring 26 and biases the poppet 18 to an open position against the second spring 26 by default. In the illustrated example, the second spring 26 is a coil spring at least partially contained within a relief valve 28 connected to the valve body 12. The relief valve 28 includes a relief valve spring 28a and a valve member 28b. The relief valve member 28b is in a closed position by default and is operable to open at a threshold pressure to reduce pressure within the pressure reducing valve 10.

[0027] A retainer 30 is positioned around the head 18b of the poppet 18. The retainer 30 houses a floating guide 32 and a ball 34 (e.g., tungsten carbide). The second spring 26 engages a flange on the floating guide 32. A pocket 32a is formed on the floating guide 32 opposite the spring 26. The ball 34 is partially positioned within the pocket 32a. A conical seat 18d is formed at the end of the head 18b of the poppet 18, and the ball 34 abuts against the conical seat 18d. The conical seat 18d, ball 34, and pocket 32a form a ball joint that applies the force of the spring 24 to the poppet 18. A small gap 36 is formed between the head 18b and the side of the floating guide 32 that flanks the pocket 32a, allowing the poppet 18 to rotate around the ball 34. This rotation ensures that the force from the spring 26 is centered on the poppet 18 even if the poppet 18 tilts slightly during operation.

[0028] At the other end of the poppet 18, the first spring 24 is positioned between the piston 38 and hardware 40. For example, the hardware 40 includes a spacer 40a, a threaded adjustment 40b, and a locking cup 40c. The spacer 40a transfers the initial force from the threaded adjustment 40b to the first spring 24 during assembly of the pressure reducing valve 10, helping to maintain the initial, default open position of the poppet 18. The threaded adjustment 40b allows for further fine-tuning of the load on the first spring 24 at the operating position of the poppet 18, and the locking cup 40c secures the spacer 40a and threaded adjustment 40b in place once the poppet position is set.

[0029] The first spring 24, which includes one or more Belleville springs, actually loads the poppet 18 via the piston 38. A bearing 42 and spacer 44 urge the piston 38 toward the poppet 18 against the biasing force of the second spring 26. The piston 38 engages the poppet 18 via a bearing 42 with a convex curved surface 42a on which the piston 38 rests. A shim 44 may be used between the bearing 42 and the poppet 18 to further adjust the initial default position of the poppet 18. The first spring 24 loads the poppet 18 via the piston 38, bearing 42, and spacer 44. The convex curved surface 42a avoids the use of a flat-on-flat interface between the piston 38 and the bearing 42. If the poppet 18 tilts during operation, the flat-on-flat interface causes the poppet 18 to be off-center. In contrast, the convex curved surface 42a keeps the force at the center of the poppet 18 even if the poppet 18 tilts slightly during use.

[0030] The piston 38 defines a plenum 38a near the end of the poppet 18. The valve body 12 has a pressure tap 48 that connects the plenum 38a to the outlet 14b. The pressure tap 48 serves to provide pressure feedback from the outlet 14b to the piston 38. Pressure within the plenum 38a acts against a second spring on the piston 38, thereby regulating the movement of the poppet 18.

[0031] The gland 18c of the poppet 18 and the piston 38 include a non-slip seal 50. The non-slip seal 50 seals against the inner surface of the valve body 12, facilitating pneumatic and / or hydraulic sealing of the valve body 12 to prevent fluid leakage. For example, the non-slip seal 50 is an elastomeric O-ring or "slipper" seal having a retainer ring (i.e., slipper) and a seal disposed within the retainer ring. In a further example, the non-slip seal 50 is an elastomeric O-ring made of, but not limited to, EPDM, HNBR, or silicone.

[0032] The non-slip seal 50 helps reduce variations in valve performance. For example, a comparative pressure reducing valve may have a relatively small poppet head, requiring a relatively large stroke to achieve a desired flow rate. At this long stroke, at a threshold stroke distance, the force experienced by the seal exceeds the static friction between the seal and the mating surface. Once static friction is overcome, the seal slides along the mating surface. This sliding action causes rapid changes in the poppet position, or step shifts. Step shifts cause simultaneous step changes in flow rate / pressure, potentially resulting in temporary fluctuations in flow rate and / or pressure of 10% or more.

[0033] In contrast, the pressure reducing valve 10 has a relatively large diameter of the head 18b. Therefore, a shorter stroke can be used to achieve the same flow rate as the comparative pressure reducing valve (i.e., the flow area is proportional to the product of the head diameter and the stroke). In the pressure reducing valve 10, the stroke distance is shorter than the threshold stroke distance at which the anti-slip seal 50 slips. Therefore, the anti-slip seal 50 may roll, but operates in a substantially anti-slip state. In this state, the anti-slip seal 50 elastically deforms as the poppet 18 moves through the stroke distance. This is shown in the representative example of FIG. 2, where the anti-slip seal 50 is initially substantially circular. As the poppet 18 moves, the anti-slip seal 50 elastically deforms (e.g., via torsional deformation), but does not slip, as indicated by the deformed seal superimposed in dashed lines. The anti-slip seal 50 on the piston 38 operates in a similar manner, elastically deforming without slipping.

[0034] The elastic deformation of the anti-slip seal 50 essentially acts as an additional spring within the pressure reducing valve 10. This is because the deformed anti-slip seal 50 tends to elastically return to its undeformed state, resisting movement of the poppet 18 and piston 38. The spring rate of the anti-slip seal 50 is predictable from its elastic properties and is considered in determining the net spring rate of the pressure reducing valve 10. That is, the net spring rate is a function of the spring rates of the first spring 24, the second spring 26, and the anti-slip seal 50. Calculation of the spring rate of the opposing springs, in particular, is well known and therefore can be determined for the pressure reducing valve 10 by one of ordinary skill in the art having the benefit of this disclosure. Therefore, the position and control of the poppet 18 are tightly controlled by considering the spring rate of the anti-slip seal 50. Furthermore, because there is virtually no slippage, step changes in outlet pressure are reduced or avoided, thereby improving valve performance.

[0035] In one example useful for implementing pressure reducing valve 10 in a rocket engine, the stroke distance of poppet 18 is about 1 mil to 3 mils, and the ratio of diameter D of head 18b of poppet 18 to stroke distance is 625:1 to 200:1. In yet another example, the spring constant of each of anti-slip seals 50 is substantially lower than the spring constant of first spring 24, for example, 1:10 or less.

[0036] Although combinations of features are shown in the illustrated examples, not all of them need to be combined to realize the benefits of various embodiments of the present disclosure. In other words, a system designed in accordance with an embodiment of the present disclosure will not necessarily include all of the features shown in any one of the figures or all of the portions shown schematically in the figures. Furthermore, selected features of one embodiment can be combined with selected features of other embodiments.

[0037] The foregoing description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples will be apparent to those skilled in the art that do not necessarily depart from the disclosure. The scope of legal protection given to this disclosure can only be determined by studying the following claims.

Claims

1. a valve body defining an inlet, an outlet, a chamber, and a flow path from the inlet through the chamber to the outlet; a poppet and valve seat disposed within the chamber, the poppet movable relative to the valve seat over a stroke distance between an open position and a closed position for flow through the flow passage, the poppet defaulting to the open position, the poppet having a head end and a shank end, the poppet having a gland circumferentially disposed near the shank end; an anti-slip seal disposed within the chamber between the gland and the valve body, the anti-slip seal sealing the poppet against the valve body within the chamber, the anti-slip seal elastically deforming as the poppet moves through the stroke distance, the elastic deformation providing elastic potential energy that acts to bias the poppet against movement; and A pressure reducing valve comprising:

2. 2. The pressure reducing valve according to claim 1, wherein the poppet has a head with a diameter D, and the ratio of the diameter D to the stroke distance is between 625:1 and 200:

1.

3. 2. The pressure reducing valve of claim 1, wherein the poppet is pressure operated.

4. 2. The pressure reducing valve of claim 1, wherein the anti-slip seal is an elastomeric O-ring.

5. 2. The pressure reducing valve of claim 1, wherein the stroke distance is 1 to 3 mils (thousandths of an inch).

6. a valve body defining an inlet, an outlet, a chamber, and a flow path from the inlet through the chamber to the outlet; a poppet having a head end, a shank end, and a gland circumferentially disposed near the shank end; a valve seat disposed within the chamber, the poppet being movable relative to the valve seat through a stroke distance between an open position and a closed position for flow through the flow passage; a first spring and an opposing second spring that biases the poppet to an open position by default against the first spring; a piston adjacent the first spring, the first spring acting on the piston to move the poppet, the piston defining a plenum; a pressure tap connecting the outlet to the plenum, wherein pressure at the outlet acts as feedback to the piston via the pressure tap, and movement of the poppet is regulated by pressure acting on the piston against the first spring; an anti-slip seal disposed within the chamber between the gland and the valve body, the anti-slip seal elastically deforming as the poppet moves through the stroke distance, the elastic deformation providing elastic potential energy that acts to bias the poppet against movement; and A pressure reducing valve comprising:

7. The pressure reducing valve according to claim 6, wherein the head abuts the valve seat when in the closed position, the head has a diameter D, and a ratio of the diameter D to the stroke distance is 625:1 to 200:

1.

8. 7. The pressure reducing valve of claim 6, wherein the head has a head diameter, and the chamber diameter at the non-slip seal of the chamber is greater than the head diameter.

9. 7. The pressure reducing valve of claim 6, wherein the anti-slip seal is an elastomeric O-ring.

10. 7. The pressure reducing valve of claim 6, wherein the stroke distance is 1 to 3 mils (thousandths of an inch).

11. 7. The pressure reducing valve according to claim 6, wherein the first spring is a Belleville spring and the second spring is a coil spring.

12. 7. The pressure reducing valve of claim 6, wherein the stroke distance is 1 to 3 mils (thousandths of an inch).

13. 7. The pressure reducing valve of claim 6, wherein the non-slip seal is non-slip along the valve body within the chamber over the stroke distance, thereby avoiding pressure steps due to slippage.

14. 7. The pressure reducing valve of claim 6, further comprising an additional anti-skid seal on the piston.

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