Four-way valve employing fluid spring

A valve assembly including a housing having an elongated bore formed therein. Inlet, outlet, and load ports communicate with the bore. A valve is positioned within the bore for controlling flow of a pressure fluid between the ports. A seal ring is mounted on the valve and disposed in sealing engagement with the housing in the vicinity of the inlet port. The seal ring is axially shiftable across the inlet port in response to shifting movement of the valve. The seal ring is mounted in an annular groove which encircles the valve and has an axial width substantially greater than the axial width of the seal ring. The seal ring is shifted axially relative to the groove by the pressure fluid supplied through the inlet port when the valve is shifted between first and second operational positions. A fluid-assisted spring means coacts between the valve and the housing, which spring means includes a spring-confining chamber defined between one end of the valve and the adjacent portion of the housing. A passage extends interiorly of the valve for providing fluid communication between the chamber and the inlet port. The passage terminates in a hole which opens through the bottom of the groove. The seal ring is movable over the hole during shifting of the valve between the first and second operational positions.

FIELD OF THE INVENTION 
This invention relates to a spool-type valve assembly for controlling the 
flow of a pressurized gas, usually air, and particularly a four-way valve 
assembly having a fluid or fluid-assisted spring means for returning the 
valve to its normal position. 
BACKGROUND OF THE INVENTION 
Valve assemblies of the type employing a shiftable spool valve commonly 
employ a mechanical spring for returning the valve spool to its normal end 
position. However, as the pressure of the fluid controlled by the valve 
increases, the valve seals are increasingly deformed, so that a larger 
return force is required for returning the valve to its normal position. 
For this reason, such valve assemblies conventionally use a fluid-assisted 
spring for returning the valve spool to its normal position, whereby the 
mechanical spring force is only strong enough to return the spool at zero 
or very low fluid pressure, whereas the air spring provides additional 
return force as the fluid pressure increases. These valve assemblies are 
normally provided with an actuator associated with one end of the valve 
spool for causing axial displacement thereof from one end position into an 
opposite end position. This actuator often comprises a fluid pilot but may 
be of many different types, such as manual, mechanical or electrical. The 
fluid-assisted spring is normally associated with the end of the valve 
spool opposite the actuator, and conventionally comprises a closed chamber 
defined between the valve spool and the housing for confining therein a 
mechanical spring. This chamber is normally in continuous communication 
with the inlet port, and for this purpose a passageway is normally 
provided either internally or externally of the housing. This makes 
manufacture of the housing more complex or, in the alternative, makes the 
overall housing bulky and cumbersome. This also results in the housing for 
a valve assembly employing a fluid-assisted spring being different from 
the housing for a valve assembly which does not employ a fluid spring, 
thereby preventing standardization of the housings. 
It is thus an object of the present invention to provide an improved valve 
assembly capable of being provided with a fluid-assisted spring, which 
valve assembly overcomes the above-mentioned disadvantages. 
More specifically, it is an object of this invention to provide an improved 
fluid-assisted spring means for use with a shiftable spool-type valve 
assembly, which spring means utilizes a communication passage extending 
interiorly of the valve spool for providing communication between the 
inlet port and the spring chamber, whereby the valve housing can be 
simplified and standardized. 
Another object is to provide an improved valve assembly, as aforesaid, 
which utilizes an O-ring positioned within an annular groove on the valve 
spool, which annular groove is of substantially greater axial width than 
the diameter of the O-ring so that when the latter is shifted axially 
across the inlet port during shifting of the spool, the O-ring is axially 
shifted relative to the spool, whereby the O-ring displacement is greater 
than the valve spool displacement so that minimum shifting of the valve 
spool is possible. 
A further object is to provide an improved valve assembly, as aforesaid, 
wherein the communication passage between the inlet port and the spring 
chamber extends axially from the spring chamber through the valve spool 
and terminates at the bottom of said groove, whereby the O-ring is rapidly 
shifted axially across the open end of the communication passage so that 
the latter provides substantially continuous communication between the 
inlet port and the spring chamber. 
Other objects and purposes of the invention will be apparent to persons 
familiar with valve assemblies of this general type upon reading the 
following specification and inspecting the accompanying drawings.

SUMMARY OF THE INVENTION 
A valve assembly including a housing means having an elongated bore formed 
therein. Inlet, outlet, and load ports are formed in the housing and 
communicate with the bore. A valve is positioned within the bore means and 
disposed in sealed slidable engagement with the housing for controlling 
flow of a pressure fluid between the ports. A seal ring is mounted on the 
valve and disposed in sealing engagement with the housing in the vicinity 
of the inlet port. The seal ring is axially shiftable across the inlet 
port in response to shifting movement of the valve. The seal ring is 
mounted in an annular groove which encircles the valve and has an axial 
width substantially greater then the axial width of the seal ring, whereby 
the seal ring can be shifted axially along the groove. The seal ring is 
shifted axially relative to the groove by the pressure fluid supplied 
through the inlet port when the valve is shifted between normal and 
actuated operational positions. A fluid-assisted spring means coacts 
between the valve and the housing for urging the valve toward its normal 
position. The spring means includes a spring chamber defined between one 
end of the valve and the adjacent portion of the housing which chamber 
confines therein a mechanical spring. A passage extends interiorly of the 
valve for providing fluid communication between the chamber and the inlet 
port. The passage terminates in a hole which opens through the bottom of 
the groove. The seal ring is movable over the hole during shifting of the 
valve between its operational positions, and the seal ring is maintained 
at one end of the groove so that the hole is uncovered and communicates 
with the inlet port when the valve is in either of said operational 
positions. 
DETAILED DESCRIPTION 
The valve assembly 10, as illustrated in FIGS. 1 and 2, includes a valve 
housing 11 having a bore 12 extending axially therethrough. A sleeve-like 
liner structure 13 is fixedly positioned within the housing bore, thereby 
effectively comprising a part of the housing, which liner structure itself 
defines a valve bore 14 in which a spool valve 15 is axially slidably 
disposed. 
Housing 11 has a plurality of ports therein, namely five ports in the 
illustrated embodiment. A supply or inlet port 16 projects radially of the 
housing for communication with the valve bore, which inlet port 16 is 
adapted for connection in a conventional manner with a supply of pressure 
fluid, such as pressurized air. A pair of exhaust or outlet ports 17 and 
18 are disposed on opposite sides of the inlet port and also project 
radially of the housing for communication with the valve bore adjacent the 
opposite axial ends thereof. The housing also has a pair of load ports 21 
and 22 formed therein, which load ports communicate with the valve bore on 
opposite sides of the supply port 16. 
The sleeve-like liner structure 13 includes a pair of identical liner 
segments 23 and 24 which are fixedly disposed in axially opposed 
relationship within the reduced-diameter center portion of the housing 
bore 12. These liner segments have annular flanges 26 at their outer ends, 
which flanges seat against appropriate housing shoulders for retaining the 
liner segments 23 and 24 in a preselected spaced relationship to result in 
a narrow annular gap 27 being defined therebetween. This annular gap 27 
provides communication between the valve bore 14 and an annular 
compartment 28 which is defined in surrounding relationship to the liner 
segments, which compartment 28 is in continuous communication with the 
supply port 16. 
The liner segment 23 is fixedly and sealingly supported within the housing 
bore by a pair of axially spaced O-rings 29. An annular compartment 31 is 
defined between the O-rings 29 in surrounding relationship to the liner 
segment 23, which compartment 29 is in continuous communication with the 
load port 21 and is also in communication with the valve bore by means of 
one or more small openings 32 which extend radially through the liner 
segment 23. 
The liner segment 24 is supported in a manner similar to the segment 23, in 
that it is stationarily and sealingly supported within the housing bore by 
a pair of spaced O-rings 33. An annular compartment 34, which is in 
continuous communication with the other load port 22, is defined between 
the O-rings 33 in surrounding relationship to the liner segment 24. This 
compartment 34 is also in continuous communication with the valve bore 14 
through one or more small holes or ports 35 which extend radially through 
the liner segment. 
Liner structure 13, in addition to segments 23 and 24 described above, also 
includes additional liner segments 36 and 37 which are disposed adjacent 
the opposite ends of the valve housing. These liner segments 36 and 37 are 
disposed within the enlarged-diameter portions of the housing bore as 
disposed adjacent the opposite ends of the valve housing. These end liner 
segments are fixedly and sealingly connected to the valve housing, as by 
means of threaded connectors 38. 
The liner segment 36 has an annular compartment 41 disposed in surrounding 
relationship therewith and positioned in continuous communication with the 
exhaust port 17. This compartment 41 in turn communicates with the valve 
bore 14 through a plurality of radially extending openings 42 formed in 
the liner segment 36. 
The other liner segment 37 similarly has an annular compartment 43 disposed 
in surrounding relationship therewith and in continuous communication with 
the other exhaust port 18. A plurality of openings 44 extend radially 
through the liner segment 37 for providing communication between the valve 
bore 14 and the annular compartment 43. 
In the illustrated embodiment, the liner segment 37 is of a sleeve-like 
construction and has an actuator piston 45 slidably disposed within the 
bore 46 thereof. An O-ring 47 coacts between piston 45 and bore 46 to 
create a sealed relationship therebetween. The actuator piston is normally 
maintained in the position illustrated in FIG. 1 wherein it abuts against 
an internal shoulder 48 formed on the liner segment 37. A pilot port 49 is 
formed in the free end of the liner segment 37, which pilot port is 
connected in a conventional manner to a source of pressurized pilot fluid 
for causing actuation, that is, axially shifting of the spool valve 15. 
Considering now the spool valve 15, same is formed as an elongated 
cylindrical rod member 51 which, in the central portion thereof, is 
provided with a surrounding annular groove 52 in which is confined an 
elastomeric O-ring 53 disposed in sealing engagement with the valve bore 
14. The annular groove 52 has a width, as measured in the axial direction 
of the valve spool, which is substantially greater than the diameter of 
the O-ring 53 so that the O-ring can shift axially relative to the valve 
spool through a substantial distance. 
The valve member 51 has a pair of further annular grooves 54 and 55 formed 
thereon adjacent the opposite ends thereof, which grooves confine therein 
additional elastomeric O-rings 56 and 57, respectively, which O-rings are 
also adapted to be disposed in sealing engagement with the valve bore 
defined within the liner segments 23 and 24. The valve member 51 is of 
substantially smaller diameter than the surrounding valve bore so as to 
define therebetween a first annular flow passage 58 as disposed axially 
between the O-rings 53 and 56, with a further annular flow passage 59 
being disposed between the O-rings 53 and 57. 
A further elastomeric O-ring 61 is confined within the end liner segment 36 
and is disposed in slidable sealed engagement with the periphery of the 
valve member 51 adjacent one end thereof. Another elastomeric O-ring 62 is 
mounted on the valve member 51 adjacent the other end thereof, and is 
disposed in sealed engagement with the actuator piston 45. 
As illustrated in FIG. 1, the end liner segment 36 is of a cup-shaped 
configuration and thereby closes one end of the housing bore 12. A 
fluid-assisted spring means 63 is defined between the liner segment 36 and 
the valve spool 15 for normally resiliently urging the valve spool toward 
its normal operational position as shown in FIG. 1, although this spring 
means 63 also cushions the movement of the valve spool when it is shifted 
into its actuated operational position illustrated in FIG. 2. 
The fluid-assisted spring means 63 is formed by an internal bore 64 formed 
within the liner segment 36, which bore receives therein the projecting 
end of the valve member and is in open communication with an interior bore 
65 which projects axially inwardly of the valve member throughout a 
substantial extent thereof. These bores 64 and 65 cooperate to define a 
spring chamber or compartment 66 for containing a quantity of pressurized 
working fluid, usually air. The spring chamber 66 is closed except for its 
communication with a small hole or port 67 which projects radially of the 
valve member and communicates with the annular groove 52 substantially in 
the middle thereof. The groove 52 is of sufficient axial width such that, 
when the O-ring 53 is disposed at either axial end of the groove, the port 
67 is uncovered so as to permit its communication with the supply port 16. 
The spring means 63 also includes a conventional mechanical compression 
spring 69 confined within the spring chamber 66 and coacting between the 
liner segment 36 and the valve member 51 for normally urging the valve 
spool 15 leftwardly into its normal operational position of FIG. 1. The 
mechanical spring 69 is normally strong enough to return the valve spool 
15 leftwardly from the FIG. 2 to the normal FIG. 1 position only when the 
working fluid supplied to inlet port 16 is at a very low pressure, such as 
a pressure approaching zero. 
OPERATION 
The operation of the valve assembly 10 will be briefly described to insure 
a complete understanding thereof. 
The valve assembly is normally maintained in its normal operational 
position illustrated in FIG. 1 due to the leftward urging of the valve 
spool 15 by the mechanical spring 69. When in this position, the working 
fluid (such as air) is supplied through port 16 and then through annular 
passage 27 into the valve bore, and specifically into the annular flow 
passage 58. The working fluid then flows through liner openings 32 into 
the load port 21 for supply to a source of use, such as one end of a 
pneumatic cylinder. The pressure fluid flowing from the inlet port 16 
through the annular passage 27 acts against the central O-ring 53 and 
thereby maintains same against the leftward end of the groove 52. The 
O-rings 53 and 56 are respectively disposed in sealing engagement with the 
liner segments 24 and 23 so that the inlet port 16 is thus connected in 
fluid communication solely with the load port 21. The other load port 22 
is in open communication with the exhaust port 18 due to the O-ring 57 
being spaced outwardly from, and hence not sealingly engaged with, the 
liner segment 24. 
When in the normal operational condition of FIG. 1 as described above, the 
pressure fluid flowing through inlet port 16 and hence through annular 
passage 27 also communicates with the spring chamber 66 through the 
intermediate radial port 67, which radial port is uncovered due to the 
pressure fluid maintaining the O-ring 53 against the leftward end of the 
groove 52. The supplied pressure fluid is thus in continuous communication 
with the spring chamber 66 so that a quantity of the pressurized working 
fluid is confined therein. 
To actuate the valve into the other operational position illustrated in 
FIG. 2, a pressurized pilot fluid is supplied through port 49 and acts 
against the exposed ends of the actuating piston 45 and spool valve 15, 
whereby they are shifted rightwardly into the position of FIG. 2, the 
extent of such shifting being limited by the abutment of the skirt on the 
actuating piston 45 against the flange 26 on the liner segment 24. During 
this rightward shifting of the spool valve, the O-ring 57 is first moved 
into sealing engagement with the liner segment 24 to isolate the exhaust 
port 18 from the load port 22, and to provide proper support and 
confinement of the O-ring 57 to prevent it from being dislodged from its 
groove when exposed to the inlet port pressure. Slightly after the 
engagement of O-ring 57 with the liner 24, the central O-ring 53 is moved 
across the annular gap 27 so that the supply port 16 is only momentarily 
isolated or shut off from the valve bore 14. As soon as the O-ring 53 
moves sufficiently across the annular gap 27 so as to again partially open 
same, then the pressurized working fluid from port 16 flowing through the 
annular gap 27 acts against the leftward side of O-ring 53 and forces the 
O-ring 53 to rapidly move into a position adjacent the rightward end of 
the annular groove 52. This thus not only accelerates the uncovering of 
the annular gap 27, but also results in the O-ring 53 being rapidly moved 
into sealing engagement with the liner segment 23. 
During the rapid shifting of the O-ring 53 from one end of groove 52 to the 
other end thereof, which rapid shifting is caused by the inflowing 
pressurized working fluid, the O-ring 53 momentarily passes over and 
closes off the port 67 associated with the spring chamber 66, although as 
soon as the O-ring 53 reaches the rightward end of groove 52, the port 67 
is again fully open so that the spring chamber is again in continuous 
communication with the inlet port 16. At this time, the inlet port 16 now 
communicates through the annular flow passage 59 and through the holes 35 
with the other load port 22, which in turn is connected to a suitable 
load, such as the opposite end of a pneumatic cylinder. 
Substantially simultaneous with the rightward movement of O-ring 53 into 
overlapping engagement with annular gap 27, the O-ring 56 is moved 
rightwardly out of engagement with the liner segment 23 so that the 
previously pressurized load port 21 is thus disposed in open communication 
with the other exhaust port 17 to permit discharge of the working fluid. 
The rightward shifting of valve spool 15, as above described, results in 
the volume of the spring chamber 66 being decreased. This decrease in 
volume of the spring chamber causes the working fluid therein to be 
momentarily compressed so as to increase the pressure thereof, due to the 
restricted rate at which the working fluid can escape from the spring 
chamber 66 in view of the small diameter of the port 67. This thus 
cushions the shifting of the valve spool and prevents same from severely 
impacting against the valve housing upon reaching its extreme 
rightwardmost position. 
The valve spool will remain in the rightwardmost position of FIG. 2 so long 
as the pilot fluid is supplied to the pilot port 49. When the supply of 
pressurized pilot fluid to the port 49 is discontinued, then the return 
force exerted by the spring means 63 automatically moves the valve spool 
leftwardly into its original normal position as illustrated in FIG. 1. 
During this return movement of the valve spool, which occurs in exactly 
the opposite manner to that described above with respect to the rightward 
shifting thereof, the return force exerted on the valve spool is a 
combination of the force developed by the mechanical spring 69 and the 
pressure force of the fluid spring formed by the confinement of the 
pressurized working fluid within chamber 66. 
One of the advantageous features of this valve assembly is that, by 
positioning the central O-ring 53 within an axially elongated annular 
groove 52, and by utilizing the incoming pressure fluid for causing axial 
shifting of the O-ring relative to the valve spool, the axial displacement 
of the valve spool can be reduced inasmuch as this displacement is less 
than the total displacement of the O-ring 53 when it shifts between its 
sealed positions disposed on opposite axial sides of the annular gap 27. 
By thus minimizing the required magnitude of spool valve movement, this 
thus permits the valve assembly to be actuated by a wider range of 
operators, which operators can themselves be operationally and/or 
structurally simplified. For example, while the illustrated embodiment 
discloses operation by means of a pilot fluid, it will be appreciated that 
the valve spool could also be shifted by means of a manually push or pull 
button, by means of an electrical solenoid, or by other mechanical means. 
By permitting minimization in the stroke or required shifting movement of 
the valve spool, the operator can be substantially simplified, 
particularly in those instances where the operator comprises an electrical 
solenoid or a fluid-actuated pilot piston. 
While FIGS. 1 and 2 disclose a pilot actuation of the valve assembly, and 
as such utilize a slidable actuator piston 45 disposed between the valve 
spool 15 and the liner segment 37, it will be recognized that other types 
of operators will permit elimination of the actuator piston 45, in which 
case the end of valve spool 15 would be disposed in sealed slidable 
engagement directly with the end liner segment. 
While the above description relates to the use of the compartment 66 as an 
air spring and cushion, it will be appreciated that the basic structure of 
this invention involving the use of the shiftable O-ring passing over the 
radial port which is formed in the valve member and communicates with a 
closed compartment or chamber at one end thereof, would also be applicable 
in situations where this structure functions as a pressure-type pilot for 
causing shifting of the valve spool in at least one direction. 
In the valve assembly of this invention, the central O-ring 53 is 
preferably of a rather large diameter, and particularly is of larger 
diameter than the O-rings 56 and 57, so as to permit the O-ring 53 to be 
effectively axially shifted within the groove 52 without being subjected 
to undesirable failure, while at the same time preventing the O-ring from 
being extruded out of its groove due to the fluid pressure applied 
thereto. 
Although a particular preferred embodiment of the invention has been 
disclosed in detail for illustrative purposes, it will be recognized that 
variations or modifications of the disclosed apparatus, including the 
rearrangement of parts, lie within the scope of the present invention.