US2971522A

US2971522A - Flow proportioning valve

Info

Publication number: US2971522A
Application number: US685308A
Authority: US
Inventors: Richard L Lewis
Original assignee: Bendix Corp
Current assignee: Bendix Corp
Priority date: 1957-09-20
Filing date: 1957-09-20
Publication date: 1961-02-14
Anticipated expiration: 1978-02-14

Description

Feb. 14, 1961 R. L. LEWIS 2,971,522 FLOW PROPORTIONING VALVE Filed Sept. 20, 1957 INVENTOR.

RICHARD L. LEWIS E LE BY ATTORN Y Unite States Patent FLOW PROPORTIONING VALVE Richard L. Lewis, St. Joseph, Mich., assignor to The Bendix Corporation, a corporation of: Delaware i Filed Sept. 20, 1957, Ser. No. 685,308

4 Claims. (Cl. 137-101) The present invention relates to control valves of the slide valve type; and more particularly to the provision of rotational dither for such valves to overcome static friction and make possible easier and more accurate control of the valve.

An object of the present invention is the provision of a new and improved spool valve construction wherein rotational dither is provided to keep the spool member alive, or rotating so as to make possible easier and more accurate positioning of the spool.

Another object of the present invention is the provision of a new and improved spool valve construction wherein a flow path through the spool is provided which changes the direction of flow in such manner as to provide a reaction whose line of force is spaced apart from the axis of the valve to provide a turning moment which keeps the valve rotating.

Another object of the present invention is the provision of a new and improved spool valve in which a pair of flow paths are provided which conduct flow through the spool member in opposite directions to provide axial force components which substantially balance each other and which provide lateral force components which rotate the spool member.

A further object of the invention is the provision of a new and improved spool valve of the flow equalizing type adapted to control the flow distribution between a feed port and two motor ports and comprising: a cylindrical chamber with a valve spool therein dividing the chamber into opposite end opposing chambers to which the motor ports communicate, the opposite end edges of the spool valve member being adapted to throttle flow through either of the motor ports when moved in the direction of the respective port, said spool valve member having a generally centrally located recess commmunicating with said feed port, and a pair of flow restricting passageways communicating said recess with respective ones of the opposing end chambers, to regulate the pressure in said opposing end chambers in such manner as to maintain the flow through said motor ports at a substantially fixed ratio, said flow restricting passageways also diverting their respective flows in the same lateral direction to rotate said spool while fluid flows therethrough.

The invention resides in certain constructions and combinations and arrangements of parts, and further objects and advantages will be apparent to those skilled in the art to which the invention relates from the following description of the preferred embodiment described with refof a cutter bar table in such a manner as to lift the table uniformly regardless of the manner in which the load is distributed on the table. These tables are usually quite heavy and cumbersome when designed to be actuated by means of a single lift located at the center; and can be lightened appreciably when designed to be actuated by a pair'of cylinders at opposite sides. In order to be operable, however, flow must be distributed equally to both cylinders and requires the use of a flow equalizing valve which positions itself more precisely and accurately than any flow equalizing valve that has been produced heretofore. While the invention is believed to have particular advantages in fiow distribution valves of this type, it will be apparent to those skilled in the art, however, that the principles of the invention will have application in spool valves generally.

The valve shown in Figure 1 comprises a body member A having a generally longitudinally extending cylindrical chamber 10 therein, the sidewalls of which are provided with a first motor port 12, a feed port 1 1, and a second motor port 16 spaced longitudinally of the chamber in that order. A spool shaped movable valve member B is positioned in the longitudinally extending chamber 10 with its opposite ends intersecting a portion of the respective ones of said motor ports in such manner that movement of the spool valve member B towards the motor port 12 causes the adjacent land portion 18 to close off the first motor port 12 while increasing the exposed port area of the second motor port 16; and movement of the spool valve member B towards the second motor port 16 causes the adjacent second land portion of the spool valve member to close oit the second motor port 16 while increasing the exposed port area of the first motor port 12. Each of the first and

second land portions

18 and 20 respectively are sized to provide a sliding sealing fit with respect to the side walls of the longitudinally extending cylindrical chamber 1t and each have a sufiicient axial width to at all times isolate the feed port 14 from each of the motor ports 12 and 16 respectively. A suitable tapped drilling 22 in the body member A communicates with the feed port i i to provide a connection by which the port may be connected to a source of hydraulic pressure, and an annular recess 24 is provided in the spool member B opposite the feed port 14 to distribute pressure fluid evenly around the spool member. In order that flow through the motor ports 12 and 16 will not create side thrusts against the spool member which make the spool valve hard to slide in its chamber, the motor ports 12 and 16 are formed by means of

transversed drillings

26 and 28 respectively which extend through the opposite side walls of the chamber 10. The outer end of the

transversed drillings

26 and 28 respectively are closed off by respective ball plugs 35, and the portions of the transversed drillings positioned on opposite sides of the chamber 10 are communicated with the respective drilled and tapped

openings

34 and 36 in the outer surface of the body member A by means of a'ngularly disposed

drillings

38 and 40 for the motor port 12; and

drillings

42 and 44 for the motor port 16. The opposite ends of the cylinder chamber 15 are closed oif by means of threaded plugs as and 43 respectively to provide opposing end chambers 5d and 52. which communicate with the motor ports 12 and 16 respectively. As a further aid to centering the spool valve structure B in the cylindrical chamber 10, annular grooves 5'4 and 56 are provided in the first and second land portions 18 and 2t respectively to distribute pressure leakage evenly around the spool member.

Fluid flow from the feed port 14 is conducted to each of the opposite end

opposing chambers

50 and 52 and in turn to the motor ports 12 and 16 respectively by means of a pair of flow conducting passageways 58 and 3 60 in the first and

second land portions

18 and 20 respectively. The flow conducting passageways 58 and 60 are formed by means of longitudinal drillings extending between the opposite ends of the spool member B and the annular recess 24, and are preferably positioned as close to the radially'outer edge of the spool member B as is possible. According to further principles of the present invention tubular members bent at 90 or elbows 62 and .64 are inserted in the ends of the flow conducting passageways 58 and 60 respectively to discharge flow from the feed port 14 into the

opposing end chambers

50 and 52 respectively in the same lateral or tangential direction to produce a reaction upon the spool member B which causes it to rotate in its cylinder it} whenever fluid is being conducted through the valve. The

elbows

62 and 64 may be suitably afiixed to the spool member in any convenient manner; and as shown, the sidewalls of the flow conducting passageways 58 and 66 have been recessed to receive a strip of solder material which when heated flows around the respective elbow to solder it to the spool member B. In the embodiment shown in the drawing, the

elbows

62 and 64 are sized in such a manner as to provide a flow restriction between the feed port 14 and the opposite end

opposing chambers

50 and 52 so as to provide pressures in each of the opposing chambers which will be generally inversely proportional to the flow through each of the respective flow pathsthereby causing the spool to shift and produce an increased throttling effect in the motor port through which the greater flow is being experienced. In the embodiment shown, the spool member B shifts itself to distribute the flow through the valve evenly between the motor ports 12 and 16. The

elbows

62 and 64 discharge their fluid in the same lateral direction to produce a turning moment or reaction upon the spool member B to rotate the spool member continually while fiow passes through the spool member. It will be seen that fluid flowing through each of the flow conducting passageways 58 and 60 changes direction from a direction generally lengthwise of the spool to a direction extending generally laterally or tangentially to the spool to produce reactions on the spool member having components in the axial and the tangential directions. In the embodiment shown in the drawing, the axial components of the reactions of the respective flow paths will oppose or cancel each other, such that the resulting forces do not tend to shift the spool member B axially of its cylinder; and the tangential components of the respective flow paths, being in the same direction, rotate the spool member B in its adjusted position. apparent to those skilled in the art that the principles above described will have applications in still other types of spool valves.

As previously indicated the valve shown in the drawing is intended to be used in the system wherein pressure fluid from a pump is connected to the feed port 14 and the individual ones of a pair of single acting lift cylinders are connected to the respective motor ports 12 and 16. Assuming that the lift cylinders are in their down posi- It will be tion, and that a control valve is opened to admit pressure fluid to the feed port 14, pressure admitted to the recess 24 will proceed through each of the flow conducting passageways 58 and 60 and their cooperating elbows 62 and 64- to the

opposing chambers

50 and 52 respectively. Fluid admitted to the respective end chambers 50 and 52'will proceed out of the respective motor ports 12 and 16 to the individual ones of the pair of lift cylinders. If the load on the table actuated by the lift cylinders is not evenly distributed, a greater pressure must be delivered to one of the cylinders than is delivered to the other,

the

elbows

62, 64, which are sized in such a way as to produce pressures in each of the end

opposing chambers

50 and 52 respectively, which vary generally inversely proportionally to the amount of fluid flowing to each of the motor ports. Upon an increase of back pressure to either of the ports (and for the moment let us assume that the increased back pressure is being experienced in the second motor port 16), a smaller overall pressure drop will be experienced from the feed port 14 to the second motor port 16 than is being experienced between the feed port 14 and first motor port 12, such that a very,slight reduction in flow develops out of the second motor port 16. A reduction in the flow to the motor port 16 decreases the amount of fluid flowing through the flow conducting passageway 60 thereby increasing the pressure within the opposing end chamber 52. Increased pressure in the chamber 52 shifts the spool valve member B in the direction of the opposite end chamber 50 to close off a greater portion of the motor port 12 to thereby increase the resistance in flow there through, while at the same time uncovering a portion of the second motor port 16 to decrease resistance to flow out of the second motor port 16. The resulting movement of the spool member B, therefore, causes the pressure within the end chamber 52 to decrease somewhat while the pressure in the opposite end chamber 50 in creases somewhat; such that the pressures are again balanced, and the flows are again equally distributed to each of the motor ports 12 and 16. A similar operation would result upon a build-up of back pressure against the first motor port 12; but in this instance, the spool member B would be shifted towards the opposite end chamber 52 to permit the flow to again be equalized with respect to each of the motor ports 12 and 16.

The direction of flow through each of the flow conduct-- ing passageways 58 and 60 and the spool member B is changed from a direction lengthwise of the spool to a lateral or tangential direction by the

elbow members

62 and 64 respectively. The reactions produced by the change in direction of the fluid flowing through each of the passageways 58 and 60 rotate the spool member B continually so long as flow is being conducted through the valve. Rotational dither is thereby produced such that the surfaces of the spool member B are always in motion with respect to the cylinder chamber 10, thereby causing the coeflicient of friction experienced between the spool member B and its chamber 10 to be a dynamic one, which is largely overcome by the rotational forces. It is a well known principle that the static coefficient of friction always exceeds the dynamic coeflicient of friction, and it will therefore be seen that the spool member B may be more easily shifted with respect to its cylinder chamber 10 as a result of the rotational dither. Once the spool member B is rotating with respect to its cylinder it will be seen that no breakaway force is necessary to shift the spool member B with respect to its cylinder. Breakaway force, in a spool valve, always prevents the spool from being completely adjusted to its set point. It will therefore be seen that the rotational dither provided by the present invention permits the spool valve member to be positioned more accurately than could be achieved without it. Additional ease in movement is achieved in the construction shown in the drawing by the balancing of the pressure forces around the spool member B as is produced by the recesses 54 and 56 in the

land portions

18 and 20 respectively, and is further achieved by the forming of the motor ports 12 and 16 by means of transversed drillings which conduct the flow out of the chamber 10 from its opposite side walls.

In the preferred embodiment the weight and position of the

elbows

62 and 64 will be such as to make the spool shaped valve member B statically as well as dynamically balanced.

While the preferred embodiment of the invention has been described in considerable detail,-l do not wish to be limited to the particular constructions shown and described, and it is my intention to cover hereby all adaptations, modifications and arrangements thereof which come within the practice of those skilled in the art.

I claim:

1. In a flow dividing valve for distributing flow between first and second motor parts: a body member having an enclosed cylindrical valve chamber therein with sidewalls spaced about a longitudinal axis, a movable valve member in said chamber forming first and second opposite end opposing chambers, means defining a first flow path passing through said first opposing chamber and said movable and body members to said first motor part, means defining a second flow path passing through said second opposing chamber and said movable and body members to said second motor part, said first flow path being constructed and arranged to produce a pressure drop in said first opposing chamber which varies with flow and which changes direction of fluid flow in said movable member to produce a reaction on said movable member having an axial component and a tangential component which acts on a line of force spaced from said axis to produce a turning movement on said movable member, said second flow path being constructed and arranged to produce a pressure drop in said second opposing chamber which varies with flow and which changes direction of fluid fiow in said movable member to produce a reaction on said movable member having an axial component and a tangential component which acts on a line of force spaced from said axis to produce a turning movement on said movable member, the axial components of said first andsecond flow paths substantially balancing each other and the tangential components of said first one second flow paths producing moments in the same direction, and suitable adjustable throttling means in said first and second flow paths constructed and arranged to reduce flow through said first flow path when pressure unbalance in said opposing chambers is created in favor of said second opposing chamber and to reduce flow through said second flow path when pressure unbalance in said opposing chambers is created in favor of said first opposing chamber.

2. In a How dividing valve: a body member having an enclosed chamber therein having generally cylindrically shaped sidewalls spaced around a longitudinal axis; a first motor port, a feed port, a second motor port, arranged lengthwise in that order in the sidewalls of said chamber; a spool valve in said chamber dividing said chamber into first and second opposing end chambers, said spool valve having a recess in communication with said feed port and first and second land portions which separate said recess from respective first and second motor ports; a first flow path in said first land portion for communicating said recess with said first motor port and being constructed and arranged to throttle fluid flow in said first flow path when said spool valve is moved toward said first opposing end chamber; said first flow path having a flow restriction in said first land portion of said spool valve, and the portion of said first fiow path downstream of said flow restriction from said recess being communicated with said first opposing end chamber; and a second flow path in said second land portion for communicating said recess with said second motor port and being constructed and arranged to throttle flow through said second flow path when said spool valve is moved toward said second opposing end chamber; said second flow path having a flow restriction in said second laud portion of said spool valve and the portion of said second flow path downstream of said flow restriction from said recess being communicated with said second opposing end chamber; said first and second flow paths each changing the direction of flow through the spool valve in a manner producing a reaction on the spool member having an axial component and a tangential component which acts on a line of force spaced from said axis, the tangential components of said flow paths acting in the same general directions to rotate the spool valve during flow therethrough and the axial components being in opposition to each other.

3. In a flow dividing valve: a body member having an enclosed chamber therein having generally cylindrical- 1y shaped sidewalls spaced around a longitudinal axis; a first motor port a feed port, and a second motor port arranged lengthwise in that order in the sidewalls of said chamber; a spool valve in said chamber dividing said chamber into opposite opposing end chambers, said spool valve having a recess opposite said feed port and first and second land portions separating said feed port from the first and second motor ports respectively, and the opposite side edges of said first and second land portions partially closing ott said first and second motor ports respectively, said spool valve also having first and second fluid restricting flow paths communicating said recess with said first and second opposing end chambers respectively, which flow paths are spaced radially from said axis and communicate with their respective opposing chambers at angles which produce turning moments in the same direction to rotate said spool valve.

4. In a flow dividing valve: a body member having an enclosed chamber therein having generally cylindrically shaped sidewalls spaced around a longitudinal axis; a first motor port, a feed port, and a second motor port arranged lengthwise in that order in the sidewalls of said chamber; a spool valve in said chamber dividing said chamber into opposite opposing end chambers, said valve having a recess opposite said feed port and first and second land portions separating said feed port from the first and second motor ports respectively, and the opposite side edges of said first and second land portions partially closing ofi said first and second motor ports respectively,

said spool valve having first and second passages in said first and second land portions communicating said recess with respective first and second end opposing chambers; and first and second flow restricting elbows in respective first and second end opposing chambers in communication with respective first and second passages for discharging fluid from said feed port into said opposing end chambers in the same general lateral direction and at a high velocity to rotate said spool valve.

References Cited in the file of this patent UNITED STATES PATENTS Trethewey July 22, 1958 UNITED STATES PATENT OFFICE CETWICATIQN @F CQRECTIN Patent; NOW, 2 971522 February l4! 196].

Richard LB Lewis It is hereby certified that error appears in the above numbered patent requiring correction and 'that the said Letters Patent should read as corrected below.

Column $5 lines 13 and 16 for "parfi' each occurrence read We port column 6 line 42 after sald insert, we spool Signed and sealed this 5th day of September 1961a SEAL A test:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents