Valve device with annular resilient valving elements

April 11, 1961

VALVE DEVICE

e. e. hewitt 2,979,080

WITH ANNULAR RESILIENT VALVING ELEMENTS

Filed Jan. 29, 1959

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ATTDRNE/

United States Patent Office

2,979,08#

Patented Apr. 11, 1961

2,979,080

VALVE DEVICE WITH ANNULAR RESILIENT VALVING ELEMENTS

Ellis E. Hewitt, Ruffisdale, Pa., assignor to Westinghouse Air Brake Company, Wilmerding, Pa., a corporation of Pennsylvania

Filed Jan. 29,1959, Ser. No. 789,911

Claims. (CI. 137—620)

This invention relates to valve devices for controlling pressure of fluid in a fluid pressure controlled mechanism, and more particularly relates to improvements in those valve devices of the above general type which comprise annular resilient valves carried by a reciprocable generally cylindrical valve-carrying member for controlling supply of pressure fluid to and release of pressure fluid from the mechanism according -to the selected axial position of said valve-carrying member.

In valve devices of the above type it is customary to provide one or more annular cavities in the valve-carrying member which are sealingly isolated from either or both the ends of said member (and from each other if more than one cavity is employed) by annular resilient elements of the so-called O-ring type, at least two of which function as annular resilient valves, which are carried in axially spaced annular grooves formed in said member. As the valve-carrying member is moved axially to its various positions within a bore in a casing, these valves are moved selectively past supply, delivery or exhaust passages that are provided in said casing and open to the wall of said bore. In valve devices of this type heretofore proposed, the fluid pressure differential existing between the. supply passage and delivery passage or between the delivery passage and the exhaust passage will tend to blow or extrude a portion of one or another of said valves into the delivery passage or the exhaust passage, respectively, as.the valve-carrying member carries said one valve past said delivery passage in moving to a supply position, or carries said other valve past said exhaust passage in moving to an exhaust position. Under this condition, said one valve or said other valve, as the case may be, will become pinched and then “nibbled” away as it is moved beyond the respective passage over which it is passing. This “nibbling” of the valve destroys its sealing ability and permits leakage of pressure fluid along the bore from the supply passage to the delivery passage or from the latter to the exhaust passage, as the case may be, and thus materially reduces the effective life and reliability of valve devices of this type.

The principal object of this invention is therefore to provide an improved valve device of the above general type in which such extrusion and “nibbling” away of the annular resilient valves are eliminated.

This object is accomplished in the improved valve devices hereinafter described by the provision of different flow paths each including a common delivery port provided in the casing and via which pressure fluid is supplied to and released from a fluid pressure controlled mechanism. More specifically, such pressure fluid is released from the mechanism by way of a conduit always open to the delivery port, and one cavity in the valve-carrying member that is always open to an exhaust port in the casing; and such pressure fluid is supplied to the mechanism by way of a supply passage, another cavity in said member that is always open to a delivery passage, and the delivery port. A suitable annular resilient seal is disposed between the cavities and movable axially by the member, and one an2 nular resilient valve and a second annular resilient valve are respectively disposed at the remote sides of said one cavity and other cavity, so as to prevent leakage along a casing bore, in which said member is reciprocable, as 5 well as perform a valving function according to positioning of said member. With this arrangement, and according to the invention, during movement of the member to exhaust position, fluid pressure in the conduit will tend to blow said one valve away from the conduit as it is 10 moved therepast and thus prevent “nibbling” of said one valve; and during movement of said member to supply position, fluid pressure in the supply passage will tend to blow said second valve away from the supply passage as it is moved therepast and thus prevent “nibbling” of 15 said second valve.

Other oojects and advantages will become apparent from the following more detailed description of the invention and from the accompanying drawing, wherein: Figs. 1 and 2 are section views of valve devices illustrat²⁰ ing typical prior art arrangements not embodying the invention; and Figs. 3, 4 and 5 -are section views of improved valve devices illustrating different embodiments of the invention.

For facility of understanding and comparison, through²⁵ out subsequent description, like reference numerals will be employed, where appropriate, to designate elements having identical or comparable functions though not necessarily identical in structure.

Description

The valve devices shown in Figs. 1 and 2 illustrate typical prior art valving arrangements and are shown to facilitate an understanding of the undesirable characteristic which is overcome in the improved valve devices 35 which are shown in Figs. 3, 4 and 5 and -are constructed according to different embodiments of the invention.

Each of these valve devices is provided to control the pressure of fluid in a fluid pressure controlled mechanism 1, such for example, as a brake cylinder. Each ⁴⁰ of these valve devices may comprise a sectionalized casing 2 providing a bore 3 in which is reciprocably mounted a cylindrical valve-carrying member 4. Each casing 2 has a supply passage 5 chargeable with fluid under pressure from a suitable source (not shown) of pressure ⁴⁵ fluid and having a mouth open to the wall of bore 3, an exhaust port 6 illustratively shown open to the atmosphere, and a delivery port 7 suitably connectable to the mechanism 1. For sake of simplified illustration, each member 4 is illustrated as being subject to the opposing 50 bias forces of two helical springs 8, 9 of substantially equal spring force which are disposed in respective atmospheric chambers 10,11 and which, when no manual force is applied to a push-pull type of plunger 12 coaxially connected to member 4 will bias said member to a lap 55 position in which it is shown; however, it will be understood that reciprocation of the member 4 may be controlled in any well-known manner, such as remotely by a fluid pressure medium or by other mechanically actuated arrangements. Pulling the plunger 12 outwardly 60 against the force of spring 8 will shift the member 4 to a supply position, defined by contact of said member with a stop shoulder 13 in chamber 10; whereas pushing said plunger inwardly against the force of spring 9 will shift the member 4 to an exhaust position defined by con65 tact of said member with a stop shoulder 14 in chamber 11.

The member 4 of Fig. 1 has two annular resilient valves 15, 16 of the O-ring type carried in annular grooves in said member adjacent opposite ends of an annular cavity 70 17 in said member. When this member 4 is shifted against the force of spring 9 to its exhaust position, valve 16 will be carried past an exhaust passage 18 for permitting pres2,979,080 sure fluid in the mechanism 1 to flow via port 7, a delivery passage 19 and cavity 17 to exhaust passage 18. During this movement, as valve 16 moves into line with passage 18, fluid pressure in delivery passage 19 will act to blow or extrude a portion of said valve into passage 18; and when, as viewed in Fig. 1, the left wall of the groove carrying said valve moves toward the right side of passage 18, such portion can become pinched between the member 4 and casing 2 and “nibbled” away by a shearing action as said left wall moves past passage 18. This same “nibbling” will also occur during leftward movement of valve 16 over passage 18. As above noted, such “nibbling” away of the valve 16 is highly undesirable and reduces the useful life and reliability of this valve device because, after repeated shifting of member 4, valve 16 will no longer provide a positive seal when said member is in lap position or in supply position, in both of which positions valve 16 is required to prevent leakage from the delivery passage 19 to the exhaust passage 18 along bore 3.

In the valve device of Fig. 2, a somewhat similar problem is presented, as will now be demonstrated. The member 4 of this valve device has two axially spaced annular cavities 21, 22 constantly open to supply passage 5 and exhaust passage 18, respectively, between which passages is disposed the delivery passage 19. Two annular resilient valves 23, 24 are carried in spaced annular grooves in this member 4 adjacent the near ends of cavities 21, 22, respectively. When this member 4 is shifted against the force of spring 8 to supply position, valve 23 will be carried past delivery passage 19 for permitting pressure fluid to flow from supply passage 5 via cavity 21 to delivery passage 19. As valve 23 is thus shifted, the existing differential in the pressures of fluid in the passages 5, 19 will cause valve 23 to be blown or extruded into the mouth of delivery passage 19 and cause undesired “nibbling” of said valve as will be understood from the description in connection with valve 16 of the valve device shown in Fig. 1.

In the improved valve devices shown in Figs. 3, 4 and 5 and constructed according to different embodiments of the invention, no “nibbling” of any annular resilient valve of the O-ring type carried by the respective valvecarrying members 4 can or will occur, for reasons now to be explained.

Referring now to Figs. 3, 4 and 5, each member 4 carries two annular resilient valves 30, 31 and also may carry three annular resilient seals 32, 33, 34 such as of the so-called O-ring type, disposed in axially spaced annular grooves encircling said member; and said member has two axially spaced, preferably annular, cavities 35, 36 formed in its exterior. One of these cavities, 35, is constantly open to the exhaust port 6, either by way of an exhaust passage 37 formed in the casing 2 (as shown in Figs. 3 and 5) or formed in the member 4 (as shown in Fig. 4). The other cavity, 36, is constantly (as shown in Figs. 3 and 4) or normally (as shown in Fig. 5) open to the delivery port 7 by way of a delivery passage 38 which may be formed in the casing 2 and lead directly to port 7 (as shown in Figs. 3 and 4) or may be formed in the member 4 and lead in bridge-like fashion around cavity 35 to a third annular cavity 39 formed in the exterior of member 4 adjacent the end of cavity 35 remote from cavity 36 and normally open to port 7 (as shown in Fig. 5). A conduit 40 constantly open to delivery port 7 leads through the casing 2 and has a mouth that opens through the wall of bore 3 at a point in proximity of the end of cavity 35 remote from cavity 36.

The valves 30, 31 and the seals 32, 33, 34 are so arranged that when the respective valve-carrying members 4 of Figs. 3, 4 and 5 are in lap position, in which they are shown, the corresponding valve 30 and seal 33 prevent leakage of pressure fluid from the conduit 40 along the bore 3 to exhaust cavity 35 and to atmospheric chamber 11, respectively; valve 31 and seal. 34. prevent leakage of pressure fluid along the bore 3 from supply passage 5 to delivery port 7 via cavity 36 and to atmospheric chamber 10, respectively; seal 32 always being effective to prevent leakage of pressure fluid along the bore 3 from cavity 36 to exhaust cavity 35 and never riding over any passage or the conduit..

It is to be noted that whereas seals 32, 33 and 34 have been shown as carried by member 4, similar seals or suitable packing may, if preferred, be carried in annular grooves formed in the wall of bore 3, and so disposed therealong as to accomplish the same functions as seals 32, 33 and 34.

In operation, when the. valve member 4 shown in Figs. 3, 4 or 5 is pulled leftward to supply position, valve 31 will be carried past the mouth of supply passage 5 and permit pressure fluid to flow from the latter via cavity 36, delivery passage 38 and delivery port 7 to the mechanism 1; and valve 30 and seal 33 will not be carried past any passage or the conduit and will prevent leakage of pressure fluid from conduit 40 along bore 3 to exhaust cavity 35 and atmospheric chamber 11, respectively. Meanwhile, as valve 31 is carried into registry with and then past the mouth of passage 5, the existing differential between the relatively high pressure in supply passage 5 and the lower pressure in delivery passage 38 will cause valve 31 to be blown away from said mouth and into its respective groove and hence positively prevent “nibbling” of said valve.

When the valve member 4 shown in Figs. 3, 4 or 5 is pushed rightward to exhaust position, valve 30 will be carried past the mouth of conduit 40 and permit pressure fluid to flow from mechanism 1 via conduit 40, cavity 35 and exhaust passage 37 to exhaust port 6; and valve 31 and seal 34 will prevent leakage of pressure fluid from supply passage 5 along bore 3 to the delivery passage 38 via cavity 36 and to the atmospheric chamber 10, respectively. Meanwhile, as valve 30 is carried into registry with and then past the mouth of conduit 40, the existing differential between the relatively high pressure in said conduit and the lower (illustratively shown as atmospheric) pressure in the exhaust cavity 35 and exhaust passage 37 will cause valve 30 to be blown away from said mouth and into its respective groove and hence positively prevent “nibbling” of said valve.

It is to be noted that the conduit 40 is preferably connected to the delivery port 7 interiorly of the casing 2, as shown, but may, if preferred, be connected to the delivery port 7 exteriorly of the casing 2 and lead through said casing to the wall of bore 3. It will also be noted that in the valve devices shown in Figs. 3 and 4, the delivery passage 38 and conduit 40 are provided in the casing 2 and connected in parallel with the delivery port 7 so as to constitute, in effect, a passage having two branches leading to different points along the wall of bore 3 which, with the respective members 4 in lap position, are disposed adjacent opposite ends of the cavity 35 in a spanning relationship. In the valve device shown in Fig. 5, however, the delivery passage 38 and conduit 40 are provided in the member 4 and in casing 2, respectively, and connected in series except when said member is in exhaust position, in which valve 30 isolataes delivery passage 38 and cavities 36, 39 from the conduit 40, and conduit 40 is connected to exhaust port 6 via cavity 35 in bypass of the cavities 36, 39 and passage 38.

However, in each of the valve devices shown in Figs. 3, 4 and 5, “nibbling” away of the valves 30 and 31 will be positively prevented as these valves are carried into registry with and past the mouths of conduit 40 and supply passage 5, respectively, by a fluid pressure differential which always acts to blow the respective valve 30 or 31 away from said mouths and into their respective grooves in the corresponding member 4.

2,979,080