US3700004A

US3700004A - Valve structure and boost control system

Info

Publication number: US3700004A
Authority: US
Inventors: John D Tobias
Original assignee: GENEVIEVE M O HARA
Current assignee: GENEVIEVE M O HARA
Priority date: 1970-12-11
Filing date: 1970-12-11
Publication date: 1972-10-24
Anticipated expiration: 1989-10-24

Abstract

A spool valve having a sleeve member and a core member, with ports formed from two longitudinally spaced perforations extending transversely of the members parallel to and offset on opposite sides of a longitudinal plane containing the axes of the members such that, when the core is rotated 180* for use, the ports in the core are offset on opposite sides of the plane from the ports in the sleeve. The ports are preferably formed to be tangent to the plane so that rotation from the use position to one direction or the other will register one or the other of the core ports with its corresponding sleeve port. The valve is used in a boost control system in which fluid pressure is directed to the core ports through a central longitudinal bore, with a force motor selectively rotating the core in one or the other direction, depending on the functions of a fluid pressure user. This rotation alternatively opens the sets of core ports to passages in the sleeve, which are simultaneously respectively opened to boost passages in the core to assist rotation in the selected direction, and which rotation simultaneously opens a selected core port to its corresponding sleeve port, directing pressure fluid to the user as needed. Rotation also simultaneously opens the active boost passage to a sleeve passage directing fluid to a core return piston for rotating the core back to its initial position.

Description

States Patent Unite Tobias [54] VALVE STRUCTURE AND BOOST CONTROL SYSTEM [72] Inventor: John D. Tobias, Royal Oak, Mich.

[73] Assignees: John P. O'Hara, Jr.; Genevieve M. OHara, Bloomfield Township, Ohio part interest to each 22 Filed: Dec. 11, 1970 [21 Appl. No.: 97,140

[52] US. Cl ..137/625.23 [51] Int. Cl ..F16k 11/02 [58] Field of Search ..137/625.21, 625.22, 625.23,

Primary Examiner-Henry T. Klinksiek Atto'rneyl-1auke, Gifford and Patalidis ABSTRACT A spool valve having a sleeve member and a core' 1 Oct. 17,1972

member, with ports formed from two longitudinally spaced perforations extending transversely of the members parallel to and offset on opposite sides of a longitudinal plane containing the axes of the members such that, when the core is rotated 180 for use, the ports in the core are offset on opposite sides of the plane from the ports in the sleeve. The ports are preferably formed to be tangent to the plane so that rotation from the use position to one direction or the other will register one or the other of the core ports with its corresponding sleeve port.

The valve is used in a boost controlsystem in which fluid pressure is directed to the core ports through a central longitudinal bore, with a force motor selectively rotating the core in one orv the other direction, depending on the functions of a fluid pressure user. This rotation alternatively opens the sets of core ports to passages in the sleeve, which are simultaneously respectively opened to boost passages in the core to assist rotation in the selected direction, and which rotation simultaneously opens a selected core port to its corresponding sleeve port, directing pressure fluid to the user as needed. Rotation also simultaneously opens the active boost passage to a sleeve passage directing fluid to a core return piston for rotating the core back to'its initial position.

17 Claims, 12 Drawing Figures Rwa- 5.

lllv

PATENTED 0m 24 I972 SHEET 1 0F 3 FIG-3 INVENTIOR JOHN D- TOB-IAS ATTORNEYS PATENTEnnmwsn '33 700 004 sum a nr 3- FIG9 . INVENTOR JOHN TOBIAS BY W/M ATTORNEYS VALVE STRUCTURE BOOST CONTROL SYSTEM BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to spool valves and to fluid control systems in which such spool valves are used.

2. Description of the Prior Art Spool valves of many types with numerous porting variations are used in all types of fluid power and fluid control systems, generally requiring specialized and difficult manufacturing processes. With requirements for more complex fluid systems, valves have tended to become more complex also, causing increases in costs and problems of reliability. Simpler valve construction and fabrication methods are highly to be desired.

SUMMARY OF THE INVENTION My invention lies in a highly simplified spool valve in which a cylindrical core member is retained in an enclosing sleeve as a perforation is formed through one of the members and into at least one side of the other member at the interface of the members on a transverse axis parallel to and offset to one side of a plane containing the longitudinal axes of the members. The perforation may further be formed into another side of the other member on the transverse axis at two portions of the'interface of the members.

Another perforation may be similarly formed with respect to the same plane but longitudinally spaced from the first perforation, and also may be formed on an axis offset from an opposite side of the longitudinal plane.

The perforations may alternatively be made in the members separately if desired.

When the core is rotated 180 from the perforation forming position, the perforations in the members, which were registered with each other in their formation, or were made to so register, will be disposed on respective parallel axes but offset from opposite sides of the longitudinal plane.

If the perforations have been formed to be tangent to the plane, when in the 180 rotated position the ports are so located that selective rotation of the core in alternatively opposite directions will variably register one or the other of the ports in one member with the adjacent port in the other member.

Valves made by this simplified method lend themselves to innumerable uses in fluid power and/or control systems. One such inventive use comprises a boost control system in which the core member has a central bore intersecting the axes of the ports and is supplied with fluid pressure. One pair of sleeve ports is connected to afluid pressure user such as ahydraulic ram, and another pair of sleeve ports is connected to a pair. of boost passages in the core. A force motor actuates the core selectively in one direction or the other to variably direct fluid pressure simultaneously to the user from one port and to the respective boost passage which is shaped so that the pressure assists rotation of the core. Simultaneously, another port in the sleeve communicates with an outlet from the boost passage to direct pressure to a piston operatively actuating the core back to its initial neutral position. Thus, the simplified valve is adapted by merely making the necessary port connections to accomplish manifold functions needed in a fairly complex boost control system.

It will be clear from the present description that such a valve can be readily adapted to many other types of fluid systems.

DESCRIPTION OF THE DRAWINGS For a more complete understanding of the invention, reference may be had to the accompanying drawings illustrating preferred embodiments thereof in which like reference characters refer to like parts throughout the several views and in which:

FIG. 1 is an exploded perspective view of a spool valve assembly embodying the invention,

FIG. 2 is a diagrammatic cross-sectional view of a valve assembly and tool following the making of a portforming perforation,

FIG. 3 is a diagrammatic cross-sectional view of the assembly of FIG. 2 with the core rotated to its neutral operative position,

FIG. 4 is a diagrammatic cross-sectional view of the spool valve assembly and tool following the making of an alternative port-forming perforation,

FIG. 5 is a diagrammatic cross-sectional view of the assembly of FIG. 4 with the core rotated 180 to its neutral operative position,

FIG. 6 is an elevational view of a boost control system unit embodying a spool valve assembly as in FIG. 1 adapted to a structure incorporating core return pistons,

' FIG. 7 is a longitudinal cross-sectional view taken substantially on the line 77 of FIG. 6,

FIG. 8 is a transverse cross-sectional view taken substantially on the line 88 of FIG. 7,

FIG. 9 is a cross-sectional view as in FIG. 8 but with the core rotated to full boost position,

FIGS. 10 and 11 are transverse cross-sectional views taken substantially on the lines 10-10 and 11-11 of FIG. 7, and

FIG. 12 is a diagrammatic view of a fluid system embodying the unit of FIGS. 6 through 11.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 illustrates in exploded view a valve assembly 10 as comprising a cylindrical sleeve member 12 having a longitudinal bore 14 extending therethrough and adapted to closely enclose a cylindrical hollow core member 16.

The sleeve member 12 is perforated on transverse axes A and B, forming

ports

18, 20, 22 and 24 as shown, while the core member 16 is perforated on axes A and B, forming

ports

26, 28, 30 and 32. It will be seen that the perforation axes A and B are longitudinally spaced and laterally offset on opposite sides and parallel to a plane P which contains the longitudinal axis X of the sleeve member 12, which axis is of course common to the longitudinal axis of the core member 16. The perforation axes A and B are likewise longitudinally spaced and laterally offset on opposite sides and parallel to the plane P, but, as oriented in FIG. 1 the core member 16 has been rotated 180 from its initial formed position within the sleeve member 12 so that the axes A and B are respectively on opposite sides of the plane from the axes A and B.

Also, it will be noted that the ports are all preferably tangentially adjacent the plane P, such that in the orientation shown, the sleeve ports will be closed off to provide for a prescribed degree of rotation of the core 16, in the sleeve 12 to either side of the 180 initial rotated position during which the ports will remain closed.

FIG. 2 shows, cross-sectionally, a sleeve member 12a enclosing a core member 16a and a tool 34a adapted to form a port 18a in the sleeve member 12a and

ports

28a and 26a in the core member 16a, all on the common perforation axis A which is laterally offset from the plane P which contains the longitudinal axis X.

FIG. 3 shows the sleeve member 12a and core member 16a relatively rotated 180 such that the

core ports

26a and 28a now lie on the perforation axis A offset on the opposite side of the plane P from the axis A.

In use, rotation of the core member 16a clockwise from the'position of FIG. 3 will variably open the port 26a to the port 280, while the port 28a is unused.

FIG. 4 shows a sleeve member 12b enclosing a core member 16b and a tool 34b adapted to form

ports

18b and 20b in the sleeve member 12b, and ports 28b and 26b in the core member 16b, all on the common perforation axis A which is laterally offset from the plane P which contains the longitudinal axis X.

FIG. shows the sleeve member 12b and core member 16b relatively rotated 180 so that the core ports 26b and 28b now lie on the perforation axis A offset on the opposite side of the plane P from the axis A. In use, rotation of the core member 16b clockwise will variably open the port 26b to the port 18b, and rotation counter-clockwise will variably open the port 28b to the port 20b.

It will be seen that the ports may be thus formed in an extremely simple fashion on longitudinally spaced axes A and B as in FIG. 1, and the core rotated 180 to shift the core ports to the perforation axes A and B, so that, in use, when the core member is rotated in one direction, longitudinally spaced ports on opposite sides of the plane P will open, and rotation in the other direction will open the other longitudinally spaced ports on opposite sides of the plane P.

Also, it will be seen that with the ports formed tangentially to the plane P, one set of ports will close completely immediately before the other set of ports begins to open.

It will also be seen that the core member may be turned end for end without changing any orientation of the ports.

Other unusual effects may be achieved with the valve assembly of FIG. 1. For example, on a 360 rotation from the position shown, in the direction indicated by the arrow, the valve porting will be in accord with the following schedule:

1.

Ports

28 and 30 open to ports and 22, then close;

2. Dwell period;

3.

Ports

28 and 30 open to

ports

18 and 24, and

simultaneously

ports

26 and 32 open to ports 20 and 22, then all close simultaneously;

4. Dwell period; 5.

Ports

26 and 32 open to

ports

18 and 24, then close, following which, on continued rotation, step (I) repeats with no dwell.

FIG. 1 also shows an arcuately extending port 36 in the sleeve member 12, and a port 38 provided in the side of the core member 16 on the plane P, these ports being longitudinally spaced from and preferably intermediate the previously described ports which are offset from the plane P. This construction enables one to connect a fluid source to the port 36 to introduce fluid into the center of the core member 16 through the port 38, and the

other sleeve ports

18, 20, 22 and 24 may be connected as desired into a fluid user system so that rotation of the core will selectively variably altematively open various sleeve ports to fluid inside the core. Such a valve assembly would have innumerable uses.

Alternatively, the

ports

36 and 38 could be eliminated and fluid could be introduced into the core member 16 axially, and rotation of the core 16 would selectively variably alternatively open the sleeve ports to this fluid.

It is also noted that the core member 16 may be shifted axially within the sleeve member 12 to longitudinally offset the core and sleeve ports, such that on rotation the ports would not open until the core is shifted back. Alternatively, a second set of sleeve ports could be provided, with the core member 16 shifting as desired, to permit registry of its ports with either set of sleeve ports.

Further, additional ports may be similarly formed to increase the number of fluid connections, and ports may be offset relative to other planes containing the axis A but rotated relative to the plane P of FIG. 1.

One use to which a valve assembly as hereinabove described might be put is the boost valve control system illustrated in FIGS. 6-12.

In this system, a housing 50 is provided with a cylindrical chamber 52, its ends being closed by end caps and 57. A cylindrical sleeve member 12c is retained in fixed position within the chamber 52, and carries within its bore 14c a rotatable solid ended core member 16c.

The housing 50 has a plurality of transversely extending stepped holes 54 for the provision of mounting studs (not shown) which will engage the sleeve member 120 and retain it in a non-rotatable position.

An inlet passage 56 is provided in the housing 50 and extends to a port 36c provided through a side of the sleeve 12c, as shown in FIG. 10, for communication with an inlet port 380 extending through the core member 160 into a longitudinal bore 58.

Sleeve ports 18c, 20c, 22c and 240, and

core ports

26c, 28c, 30c and 32c are formed in the sleeve member and core member respectively, substantially in the manner shown in FIG. 1. Note that FIG. 7 illustrates, for purposes of clarity, all of these ports in full line, but it will be apparent that the sleeve ports and the core ports are actually offset from the plane P which contains the axis X of the core member 16c, as previously described in relation to FIG. 1, when the core member 160 is in its neutral position, and at such time the ports are closed ofi from each other.

An actuating shaft 60 extends through the end cap 56 into the bore 58 and is secured to the core member 16c to rotate the same in a manner and for a purpose to be described.

A transverse bore 64 extends through the other end of the housing 50 as shown to retain a control piston assembly 66. The end of the core member 16c, which extends into the bore 64, is milled out or otherwise formed as indicated in FIG. 8, to form a wedge-like arm 68. A pair of piston retainers 70 are adjustably threaded into the opposite ends of the assembly 66, and carry ball-ended return pistons 72 which bear on opposite sides of the arm 68. The pistons 72 are urged inwardly by compression springs 74 adjustably seated against the inner ends of adjusting screws 76 threaded into the outer ends of the piston retainers 70 as shown, so that the core member 160 can be located accurately in its initial position with its ports closed from the sleeve ports.

Passages

78 and 80 are grooved helically around the outer periphery of the sleeve member 120 to respectively connect the sleeve ports 18c and 220 with

transverse ports

82 and 84 on opposite sides of the sleeve member 120 opening to the bore 140 to register, when the core member 16c is in its neutral position, with boost assist passages 86 and 88 provided in the core member 160 as shown in FIGS. 8 and 9.

Transverse passages 90 and 92 provided in the sleeve member 120 are normally closed off from the boost assist passages 86 and 88 respectively, but are registered with passages 94 and 96 extending across the ends of the control piston assembly 66 to communicate, through ports 97 in the retainers 70, with the inner ends of the return pistons 72, thence extending inwardly to a restricted orifice drain passage 98. The passage 98 extends longitudinally through the housing 50 to connect with a drain outlet port 100.

The fluid flow rate of the present boost control valve is limited by the stroke of the piston 72 depending on the settings of the retainers 70. Moving the retainers 70 inwardly will limit piston stroke, while moving them outwardly will increase piston stroke, so that with a single valve fluid flow can be limited to different rates.

FIG. 12 illustrates diagrammatically a preferred fluid system in which is used the boost control unit illustrated in FIGS. 6-11. As shown, a working fluid is drawn from the reservoir 102 by a pump 104 which directs pressure fluid through a conduit 106 to the inlet passage 56 of the housing 50. Fluid pressure is thus provided through the ports 36c and 380 to the inner bore 58 of the core 16c. When the shaft 60 is rotated in one direction or the other by any means such as a force motor 108, fluid under pressure will be directed from port 280 or 32c to the corresponding sleeve port 200 or 240 and thence through one or the other of the

outlets

110 or 112 to be directed through a

conduit

114 or 116 for operation of a fluid pressure user such as a hydraulic piston-cylinder assembly 1 18.

The force motor 108 is intended to provide a relatively weak torque to the shaft 60. However, fluid pressure will, upon rotation of the shaft 60, enter one or the other of the sleeve ports 18c or 22c from the

core port

26c or 300 to be directed to the boost assist passage 86 or 88, both of which are shaped to use the fluid pressure to help rotate the core member 16c in the desired direction. Simultaneous with the rotation of the core member 160, the boost assist passage 86 or 88 will progressively be closed to the

passage

82 or 84 and simultaneously progressively be opened to the passage 90 or 92.

FIG. 9 illustrates the extreme clockwise rotated position of the core member 16c, in which it will be seen that the fluid pressure in the boost assist passage 86 will be discharged into the passages and 94. The drain passage 98 being of a properly restricted orifice size, the pressure will operate on the end of the piston 72 to return the core member 160 back to its initial position in which the ports of the core and sleeve members will be closed off from each other.

In FIG. 12, a sensor 120 is shown which may be connected with the assembly 118 to sense its position and send an appropriate signal to the force motor 108. With this arrangement, the fluid pressure user may be arranged to maintain a particular selected position with variations therefrom being signalled to the force motor 108 which will operate to rotate the core member and, with the function of the boost control system as above described, an immediate adjusting pressure will be conducted to the assembly 118, the small force of the force motor 108 being augmented by the fluid pressure variably transmitted to the core member 160.

Thus, using an extremely simplified valve constructed as illustrated in FIGS. 1-5, appropriate connections may be made to the sleeve ports to function in any way desired. The boost control system described is only one of innumerable uses to which a valve of the present invention may be put.

Although I have described only a few embodiments of my invention, it will be apparent to one skilled in the art to which the invention pertains that various changes and modifications may be made therein without departing from the spirit of the invention or the scope of the appended claims.

I claim:

1. A spool valve structure comprising a cylindrical core member having an axial bore and rotatably enclosed in a sleeve member, a first perforation extending through at least one side of said sleeve member and through at least one side of said core member intersecting said bore and passing through the interface of said members on a transverse axis parallel to and offset to one side of a plane containing the longitudinal axes of said members, such that on relative rotation of said members the perforations in the members will be disposed on respective parallel axes offset from opposite sides of said plane.

2. The structure as in claim 1 wherein said perforation extends through two sides of said core member on said transverse axis at two portions of the interface of said members.

3. The structure as in claim 1 including a second perforation as therein defined with respect to said plane but longitudinally spaced from the first perforation.

4. The structure as in claim 3 wherein said perforations are offset from opposite sides of said plane.

5. The structure as in claim 4 wherein each perforation extends through two sides of said core member on said transverse axis at two portions of the interface of said members.

6. The structure as in claim 3 wherein at least one perforation extends through two sides of said core member on said transverse axis at two portions of the interface of said members.

7. The structure as in claim 3 wherein each perforation extends through two sides of said core member on said transverse axis at two portions of the interface of said members.

8. The structure as in claim 3 including another perforation extending through at least one side of said sleeve member and through at least one side of the core member intersecting said bore and passing through the interface of said members on a transverse axis contained by said plane and longitudinally spaced from said first and second perforations.

9. The structure as in claim 3 including a housing peripherally enclosing said sleeve member and having fluid passages openly connected with said first and second perforations extending therethrough.

10. The structure as in claim 1 including another perforation extending through at least one side of said sleeve member and through at least one side of the core member intersecting said bore and passing through the interface of said members on a transverse axis contained by said plane and longitudinally spaced from said first perforation.

11. The structure as in claim 1 wherein said perforation extends transversely through two sides each of said sleeve and core members at two portions of the interfaces of said members on said transverse axis.

12. The structure as in claim 1 including a housing peripherally enclosing said sleeve member and having at least one fluid passage openly connected with said first perforation extending therethrough.

13.- A boost control system comprising a. a valve housing having a cylindrical bore and a hollow cylindrical valve rotatable therein;

. means introducing fluid pressure to the interior of said valve, said valve having a pair of pressure ports and a pair of boost control ports;

c. said housing having a pair of pressure outlets adapted to alternatively conduct pressure to a user, and a pair of boost control ports;

. force means selectively tending to rotate said valve in one direction or the other to alternatively register a valve pressure port with a housing pressure outlet and simultaneously a valve boost control port with a housing boost control port;

e. said valve having a pair of boost passages adapted alternatively to communicate with said housing boost control port when registered with its respective valve boost control port;

f. said boost passages being formed to use fluid pressure to assist rotation of said valve in the direction rotated by said force means.

14. The system as in claim 13 wherein said valve has an internal axial bore, and said housing comprises a cylindrical sleeve concentrically enclosing said valve and a casing enclosing said sleeve, and having a neutral position wherein:

said valve pressure ports comprise perforations extending through one side of said valve intersecting said bore and on longitudinally spaced transverse axes parallel to and offset to opposite sides of a plane containing the longitudinal axis of said valve, and

said housing pressure outlets comprise perforations extending through one side of said sleeve on longitudinally spaced transverse axes parallel to and offset to opposite sides of said plane, each pressure outlet perforation bein adjacei it to nd disposed on the opposite side 0 said p ane mm a valve pressure port perforation.

15. The system as in claim 13 wherein said valve has an internal axial bore, and said housing comprises a cylindrical sleeve concentrically enclosing said valve and a casing enclosing said sleeve, and having a neutral position wherein:

said valve boost control ports comprise perforations extending through one side of said valve intersecting said bore and on longitudinally spaced transverse axes parallel to and offset to opposite sides of a plane containing the longitudinal axis of said valve, and

said housing boost control ports comprise perforations extending through one side of said sleeve on longitudinally spaced transverse axis parallel to and offset to opposite sides of said plane, each housing boost control port perforation being adjacent to and disposed on the opposite side of said plane from a valve boost control port perforation.

16. The system as in claim 13 wherein said valve has an internal axial bore, and said housing comprises a cylindrical sleeve concentrically enclosing said valve and a casing enclosing said sleeve, and having a neutral position wherein:

said valve pressure ports and boost control ports respectively comprise perforations extending through substantially opposite sides of said valve intersecting said bore and on longitudinally spaced transverse axes parallel to and offset to opposite sides of a plane containing the longitudinal axis of said valve, each pressure port perforation being on a common axis with a boost control port perforation, and

said housing pressure outlets and boost control ports comprising perforations extending through substantially opposite sides of said sleeve on longitudinallyspaced transverse axes parallel and offset to opposite sides of said plane, each pressure outlet perforation being on a common axis with a sleeve boost control port perforation, each sleeve pressure outlet perforation and boost control port perforation being respectively adjacent to and disposed on the opposite side of said plane from a valve pressure port perforation and valve boost control port perforation.

17. The system as in claim 13 wherein said valve has an internal axial bore openly connected with said valve pressure and boost control ports, and said housing comprises a cylindrical sleeve concentrically enclosing said valve and a casing enclosing said sleeve, wherein said means introducing fluid pressure comprises a perforation longitudinally spaced from said valve ports and extending through one side of said valve intersecting said bore,

a perforation extending through one side of said sleeve and registering with the full area of said valve perforation through rotation of said valve required for registration of said valve ports with said housing outlets and ports, and

a passage in said casing opening to said sleeve perforation.

Patent N03 ,700 .004 iemhenww Inventofls) John D. Tobias It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

IN THE SPECIFICATION Column 2, line 14, before "valve" add -spool- Column 3, line 25, change "28a" to -l8a Signed and sealed this 13th day of March 1975.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. 7 ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents F ORM PO-IOSO (IO-69) USCOMM'DC 60376-P69 U.S. GOVERNMENT PRINTING OFFICE 1 I969 0-366-334 v

Claims

1. A spool valve structure comprising a cylindrical core member having an axial bore and rotatably enclosed in a sleeve member, a first perforation extending through at least one side of said sleeve member and through at least one side of said core member intersecting said bore and passing through the interface of said members on a transverse axis parallel to and offset to one side of a plane containing the longitudinal axes of said members, such that on 180* relative rotation of said members the perforations in the members will be disposed on respective parallel axes offset from opposite sides of said plane.

13. A boost control system comprising a. a valve housing having a cylindrical bore and a hollow cylindrical valve rotatable therein; b. means introducing fluid pressure to the interior of said valve, said valve having a pair of pressure ports and a pair of boost control ports; c. said housing having a Pair of pressure outlets adapted to alternatively conduct pressure to a user, and a pair of boost control ports; d. force means selectively tending to rotate said valve in one direction or the other to alternatively register a valve pressure port with a housing pressure outlet and simultaneously a valve boost control port with a housing boost control port; e. said valve having a pair of boost passages adapted alternatively to communicate with said housing boost control port when registered with its respective valve boost control port; f. said boost passages being formed to use fluid pressure to assist rotation of said valve in the direction rotated by said force means.

14. The system as in claim 13 wherein said valve has an internal axial bore, and said housing comprises a cylindrical sleeve concentrically enclosing said valve and a casing enclosing said sleeve, and having a neutral position wherein: said valve pressure ports comprise perforations extending through one side of said valve intersecting said bore and on longitudinally spaced transverse axes parallel to and offset to opposite sides of a plane containing the longitudinal axis of said valve, and said housing pressure outlets comprise perforations extending through one side of said sleeve on longitudinally spaced transverse axes parallel to and offset to opposite sides of said plane, each pressure outlet perforation being adjacent to and disposed on the opposite side of said plane from a valve pressure port perforation.

15. The system as in claim 13 wherein said valve has an internal axial bore, and said housing comprises a cylindrical sleeve concentrically enclosing said valve and a casing enclosing said sleeve, and having a neutral position wherein: said valve boost control ports comprise perforations extending through one side of said valve intersecting said bore and on longitudinally spaced transverse axes parallel to and offset to opposite sides of a plane containing the longitudinal axis of said valve, and said housing boost control ports comprise perforations extending through one side of said sleeve on longitudinally spaced transverse axis parallel to and offset to opposite sides of said plane, each housing boost control port perforation being adjacent to and disposed on the opposite side of said plane from a valve boost control port perforation.

16. The system as in claim 13 wherein said valve has an internal axial bore, and said housing comprises a cylindrical sleeve concentrically enclosing said valve and a casing enclosing said sleeve, and having a neutral position wherein: said valve pressure ports and boost control ports respectively comprise perforations extending through substantially opposite sides of said valve intersecting said bore and on longitudinally spaced transverse axes parallel to and offset to opposite sides of a plane containing the longitudinal axis of said valve, each pressure port perforation being on a common axis with a boost control port perforation, and said housing pressure outlets and boost control ports comprising perforations extending through substantially opposite sides of said sleeve on longitudinally spaced transverse axes parallel and offset to opposite sides of said plane, each pressure outlet perforation being on a common axis with a sleeve boost control port perforation, each sleeve pressure outlet perforation and boost control port perforation being respectively adjacent to and disposed on the opposite side of said plane from a valve pressure port perforation and valve boost control port perforation.

17. The system as in claim 13 wherein said valve has an internal axial bore openly connected with said valve pressure and boost control ports, and said housing comprises a cylindrical sleeve concentrically enclosing said valve and a casing enclosing said sleeve, wherein said means introducing fluid pressure comprises a perforation longitudinally spaced from said valve ports and extending through one side of saId valve intersecting said bore, a perforation extending through one side of said sleeve and registering with the full area of said valve perforation through rotation of said valve required for registration of said valve ports with said housing outlets and ports, and a passage in said casing opening to said sleeve perforation.