Valve assembly with relief groove

A valve assembly for controlling the flow of fluid, has a passage for fluid flow therein and open and closed positions whereby fluid flow through said passage is respectively allowed and prevented. First and second mating surfaces define a contact area therebetween when the valve assembly is in its closed position. Relief means is provided for communicating fluid from the passage with an inner portion of the contact area for operably reducing a force required to disengage the mating surfaces and open the valve assembly.

This invention relates to valve assemblies for controlling flow of fluid 
under pressure through fluid moving structures and, more particularly, to 
a lift-type valve assembly for controlling uni-directional flow of fluid 
under pressure through pumps, compressors and the like. 
BACKGROUND OF THE INVENTION 
Lift-type valve assemblies are well-known in the field of fluid moving 
structures and a variety of different designs have been developed in an 
attempt to achieve efficient and reliable control of fluid movement. Such 
valve assemblies typically have valve members which are retained by 
springs in a closed position in separate inlet and outlet passages and 
prevent fluid flow therebetween. The valve members are automatically 
movable to open positions when the inlet passage fluid pressure exceeds 
the outlet passage fluid pressure by a sufficient amount. This fluid 
pressure "differential" is a function of several factors including the 
closing force exerted by the springs; the amount of surface area exposed 
to fluid pressure on either side of the valve member; and the amount of 
cohesion or "stiction" between the valve member and valve seat. In fluid 
moving structures such as pumps and compressors reducing the fluid 
pressure differential required to open the valves will generally result in 
an increase in operating efficiency, because less "work" is required to 
move an equivalent amount of fluid and because lower fluid temperatures 
will be maintained at such lower pressures. 
In operation, such valve assemblies automatically open and close very 
rapidly and the valve members strike the valve seats with considerable 
force. Therefore, the useful life of the valve members may be prolonged by 
providing a substantial contact area between the valve members and the 
valve seats to absorb the shock upon engagement as the valve closes. 
However, such a substantial contact area can be detrimental to valve 
efficiency because substantially less surface area of the valve member is 
thereby exposed to the greater inlet passage fluid pressure than is 
exposed to the outlet passage fluid pressure. Because the lifting force is 
a function of both the fluid pressure and the surface areas upon which 
such pressures act, increasing the contact area generally increases the 
required pressure differential. Also, further operating efficiency is lost 
because of the cohesion or "stiction" present thereat which tends to 
resist separation and opening of the valve assembly. Such a cohesion may 
be caused by a vacuum effect or a molecular attraction or both between the 
mating surfaces and is common in lift-type valve assemblies where such 
mating surfaces tend to be relatively close fitting to minimize fluid 
leakage. Therefore, a greater fluid pressure differential is required to 
overcome such cohesive force and fluid moving structure efficiency is 
accordingly lessened. 
Prior art valve assemblies utilizing substantial contact areas for 
increased valve life have heretofore not provided relief means for 
alleviating such problems associated with substantial contact areas 
between the valve members and valve seats. 
SUMMARY OF THE INVENTION 
In the practice of the present invention, a lift-type valve assembly is 
provided which opens in response to a lower pressure differential than 
similar prior art devices and which provides relatively long valve member 
life. The valve assembly has a fluid flow passage therein which includes 
an inlet portion and an outlet portion. A valve member is movably mounted 
between a closed position engaging a valve seat and an open position for 
allowing fluid to flow from the inlet portion to the outlet portion. 
Relief means is provided for communicating fluid from the passage with an 
inner portion of a contact area where the valve member and valve seat 
engage. The relief means thereby functions to lower the pressure 
differential which would otherwise be required to open the valve assembly. 
The fluid thus communicated engages the valve member within the contact 
area for providing additional lifting force and also facilitates breaking 
the vacuum-like cohesion between the valve member and the valve seat. 
The principle objects of the present invention are: to provide a valve 
assembly wherein an inner portion of a contact area between a valve member 
and valve seat is exposed to pressurized fluid exerting a lifting force 
against the valve member; to provide a valve assembly which relieves or 
minimizes a cohesive seal between mating surfaces whereby less work is 
required to disengage the mating surfaces and open the valve assembly; to 
provide such a valve assembly which allows a fluid moving structure to 
operate efficiently and reliably; to provide such a valve assembly which 
is adapted for use in both intake and exhaust or discharge valves; to 
provide such a valve assembly with a relief means adapted for use in 
channel valves, feather valves, flapper valves, poppet valves and plate or 
flat valves; to provide such a valve assembly for use in a lift-type valve 
structure having a valve member therein whereby the valve member is more 
easily disengaged from an associated valve seating surface and less 
pressure differential within the valve assembly is required to open same; 
to provide such a valve assembly with a substantial contact area between 
the respective mating surfaces thereof for absorbing shock upon closing; 
to provide such a valve assembly wherein the fluid is maintained at a 
lower temperature as it flows therethrough; to provide such a valve 
assembly with a relief means which communicates fluid from a fluid flow 
passage to the contact area between the respective mating surfaces to 
facilitate breaking a seal or cohesion tending to form therebetween; to 
provide such a valve assembly with a relief groove communicating fluid 
from a fluid flow passage with the intermediate groove whereby opening of 
the valve assembly is facilitated and to provide such a valve assembly 
which is economical to manufacture, efficient in use, capable of a long 
operating life and particularly well adapted for the proposed usage 
thereof. 
Other objects and advantages of this invention will become apparent from 
the following description taken in conjunction with the accompanying 
drawings wherein are set forth by way of illustration and example, certain 
embodiments of this invention. The drawings constitute a part of this 
specification and include exemplary embodiments of the present invention 
and illustrate various objects and features thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
As required, detailed embodiments of the present invention are disclosed 
herein. However, it is to be understood that the disclosed embodiments are 
merely exemplary of the invention which may be embodied in various forms. 
Therefore, specific structural and functional details disclosed herein are 
not to be interpreted as limiting but merely as a basis for the claims and 
as a representative basis for teaching one skilled in the art to variously 
employ the present invention in virtually any appropriately detailed 
structure. 
For purposes of the description herein the terms "upper", "lower", "right", 
"left", "rear", "front", "vertical", "horizontal", and directional 
derivitives thereof shall relate to the invention as oriented in FIG. 1 
for the embodiment shown in FIGS. 1 and 2, to FIG. 3 for the embodiment 
shown in FIGS. 3 and 4, to FIG. 5a for the embodiment shown therein and in 
FIG. 56, and to FIG. 7 for the embodiments shown in FIGS. 6, 7, 8 and 9. 
However, it is to be understood that the invention may assume various 
alternative orientations except where expressly specified to the contrary. 
Referring to the drawings in more detail; 
The reference numeral 1 as seen in FIGS. 1 and 2 generally indicates a 
lift-type poppet valve assembly for controlling flow of fluid under 
pressure through a fluid moving structure (not shown) such as a 
conventional piston type compressor. The present invention may be utilized 
with either intake or discharge valves or with exhaust valves in either 
single or multiple deck valve assemblies. The valve assembly 1 includes a 
seat structure 2 having an inner surface 3 and an outer surface 4 with an 
inlet passage 5 extending therebetween. A valve seat or mating surface 6 
is positioned at an end of the inlet passage 5 associated with the seal 
structure inner surface 3. A cage structure 9 having an inner surface 10 
and an outer surface 11 is suitably secured with its inner surface 10 in 
opposed relation to the inner surface 3 of the seat structure 2 whereby an 
outlet passage 12 is defined therebetween for fluid flow. 
A poppet valve member 15 is movably mounted between the seat structure 2 
and the cage structure 9 to open when fluid pressure in the inlet passage 
5 is sufficiently greater than fluid pressure in the outlet passage 12 and 
to close or engage the mating surface 6 when the fluid pressure 
differential with respect to the inlet passage 5 and the outlet passage 6 
is sufficiently decreased. A valve head or seating disc 16 includes a 
mating surface 17 thereon which is adapted for mating with the valve seat 
or mating surface 6. In FIG. 1 of the present embodiment the valve member 
15 is shown in seating engagement with the mating surface 6 of the seat 
structure 2 thereby providing a contact area 18 therebetween. The valve 
member 15 is seated on the seat structure 2 whereby the mating surface 17 
engages the mating surface 6 to substantially seal the inlet passage 5 
against fluid flow from the outlet passage 12 when the valve member 15 is 
in its closed position. 
A hollow, cylindrical valve stem 21 extends from the valve head 16 and has 
a valve stem bore 22 therein having an end portion 23 near the valve head 
16. The cage structure 9 has a guide bore 26 extending from the inner cage 
surface 10 thereof and terminating in spaced relation to the outer cage 
surface 11. The guide bore 26 is aligned with the valve seating face 6 of 
the seat structure 2. The guide bore 26 is illustrated as being a 
cylindrical recess adapted to receive the valve stem 21 in sliding 
engagement therein. The guide bore 26 has an end portion 27 with a vent 
passage 28 extending therefrom to the outer cage surface 11 to exhaust 
fluid from within the guide bore 26 and thereby facilitate lifting of the 
valve member 15. 
Resilient means such as the illustrated elongated helical compression 
spring 30 is positioned within the valve stem bore 22 and has a first end 
portion 31 engaging the valve stem bore end portion 23 and a second end 32 
engaging the guide bore end portion 27. The helical spring 30 is adapted 
for urging the valve member 15 into seating engagement with the valve seat 
or mating surface 6 to close the inlet passage 5. 
In the first embodiment of the present invention the valve member mating 
surface has a frusto-conical configuration which corresponds to the 
bevelled shape of the valve seat or mating surface 6 for engagement 
therebetween. The contact area 18 defined between the respective mating 
surfaces 6 and 17 has a first peripheral portion 35 adjacent the inlet 
passage 5 and a second peripheral portion 36 adjacent the outlet passage 
12 FIG. 1. In lift-type valves such as the poppet valve assembly 1 it is 
desirable to have a substantial contact area 18 where the respective 
mating surfaces 6 and 17 engage to distribute the impact over upon closing 
of the valve member 15. Otherwise, if the impact forces are concentrated 
on a relatively small contact area, the valve member will deteriorate more 
rapidly under its own rapid opening and closing movements. 
The valve member mating surface 17 is encircled by an intermediate groove 
37 coaxial with and in spaced relation to the first and second peripheral 
portions 35 and 36 of the contact area 18 (FIG. 2). A plurality of 
circumferentially spaced relief grooves 38 extend in a radial manner 
across the valve member mating surface 17 from respective first ends 39 
opening into the outlet passage 12 and second ends 40 opening into the 
intermediate groove 37 when the valve member 15 is in its closed position. 
Applicant has found that such interconnected intermediate and relief 
grooves tend to lower the pressure differential required to open the valve 
assembly 1 and thereby increase the efficiency of the fluid moving 
structure. The required pressure differential is lowered because the 
pressurized fluid within the grooves exerts forces against portions of the 
mating surfaces. The grooves thereby effectively increase the surface area 
of the valve member exposed to the pressurized fluid and, because greater 
lifting force will thus be exerted by the same pressure acting on a larger 
area, the required pressure differential will be decreased. Also, 
applicant theorizes that a cohesion or "stiction" forms between the mating 
surfaces and tends to resist separation therebetween and opening of the 
valve assembly. Although the exact nature of such force is unknown, it may 
be associated with a vacuum seal or molecular attraction between 
closefitting surfaces, such as the mating surfaces defining the contact 
area in the valve assembly. Applicant has found that utilizing grooves as 
shown significantly increases the efficiency of a fluid moving structure 
and it is believed that at least part of this increase is because the 
grooves facilitate breaking such a seal or cohesion. 
In operation of the valve assembly 1 as an intake valve in a piston type 
compressor (not shown), the valve member 15 is in seating engagement with 
the valve seat or mating surface 6 as shown in FIG. 1 when the valve 
assembly is in its closed position. A pressure differential is then 
created across the valve assembly 1 by decreasing the fluid pressure in 
the outlet passage 12 which lifts the valve member 15 from seating 
engagement with the valve seat or mating surface 6 whereby fluid is 
allowed to flow from the inlet passage 5 to the outlet passage 12. As 
fluid flows through the respective passages 5 and 12 the pressure 
differential therebetween is reduced such that the force exerted by the 
helical spring 30 is greater than the force created by the remaining 
differential pressure so as to return the valve member 15 to seating 
engagement with valve seat or mating surface 6. 
In operation as an exhaust or discharge valve the valve member is in closed 
position as shown in FIG. 1 and the compressor piston (not shown) than 
pressurizes fluid in the inlet passage 5 until the pressure differential 
across the valve assembly 1 is sufficient to lift the valve member 15 and 
allow fluid to flow therethrough. When the pressure differential is 
sufficiently reduced, the helical spring 30 returns the valve member 15 to 
seating engagement with the valve seating face 6. By providing the relief 
groove 38 communicating fluid from either the inlet passage 5 or the 
outlet passage 12 to the contact area 18, less pressure differential 
across the valve assembly 1 will be required to lift the valve member 15. 
The fluid moving structure will thereby be operated more efficiently and 
move equivalent amounts of fluid as conventional structures with less 
energy. Also, because of lower pressures required in the inlet and outlet 
passages 5 and 12 respectively to reciprocate the valve member 15, the 
compressed fluid will be moved at a lower temperature with a resultant 
additional increase in compressor efficiency. Further, by providing the 
relief grooves 38, the contact area 18 may be substantially larger than 
those found in conventional valve assemblies to reduce the wear on the 
valve member 15 and thereby increase the serviceable life thereof by 
distributing the impact upon closing over a larger contact area 18. 
A modified embodiment of the poppet valve assembly generally designated 1a 
having a modified valve member 15a is shown in FIGS. 3 and 4. Elements of 
the modified embodiment of the valve assembly 1a which are otherwise 
substantially the same as the previously described device 1 are 
represented by the same corresponding reference numerals except for the 
addition of the suffix "a" to the numerals of the modified structure. 
The valve member 15a includes a valve head 16a with a guide member 45 
thereon similar to that disclosed in applicants' U.S. Pat. No. 3,701,361 
for a VALVE ASSEMBLY AND VALVE MEMBER THEREFOR. The guide structure 45 
comprises an extension of the frusto-conical shaped valve member mating 
surface 17a with a plurality of angularly spaced fins 46 extending 
therefrom as best shown in FIG. 4. The fins 46 are adapted for slidably 
engaging the inlet passage 5a to thereby effect a true linear movement of 
the valve member 15a as it moves toward and away from the valve seat or 
mating surface 6a while respectively closing and opening. 
The valve member mating surface 17a has a groove 37a thereon intermediate 
and generally coaxial with first and second peripheral portions 35a and 
36a respectively of a contact area 18a. A plurality of relief grooves 41 
each has a first end 42 opening into the inlet passage 5a when the valve 
member 15a is in seating engagement with the mating surface 6a as is shown 
in FIG. 3. Each relief groove 41 also has a second end 43 opening into the 
intermediate groove 37a whereby fluid is communicated from the inlet 
passage 5a to the intermediate groove 37a and thus to the contact area 
18a. The relief grooves 41 of the modified valve assembly 1a function in 
substantially the same manner as the relief grooves 38 of the valve 
assembly 1 to reduce the fluid pressure differential across the valve 
assembly 1a required to disengage and lift the valve member 15a. However, 
unlike the first embodiment, the relief grooves 38 communicate fluid from 
the inlet passage 59 which has a higher fluid pressure therein than the 
outlet passage 12a immediately prior to the valve member opening. Such 
fluid under a higher pressure will exert a greater force within the 
contact area to lift the valve member and break the cohesion or seal. It 
is thereby anticipated that the valve assembly of this embodiment will 
require an even lower fluid pressure differential to open it than the 
first embodiment. 
FIGS. 5a and 5b illustrate a further modified poppet valve assembly 1b with 
an intermediate groove 47 and relief grooves 48 on the valve seat or 
mating surface. Since the valve assembly 1b is substantially the same as 
the previously described assembly 1, therefore similar parts appearing in 
FIGS. 5a and 5b and FIGS. 1 and 2 respectively are represented by the same 
corresponding reference numeral except for the addition of the suffix "b" 
to the numerals of the further modified valve assembly 1b. 
A valve member mating surface 17b of the further modified valve assembly 1b 
represents a substantially uniform surface having a frusto-conical 
configuration. The intermediate groove 47 is functionally equivalent to 
the other intermediate grooves 37 and 37a respectively of the first and 
second embodiments. The relief grooves 48 have first ends 49 and second 
ends 50 communicating fluid respectively from the outlet passage 12b to 
the intermediate groove 47 and thus to the contact area 18b and similarly 
facilitate lifting the valve member 15a and breaking the cohesion or 
suction seal formed at the contact area 18 by forces associated with the 
engagement of two closely mating surfaces. As with the previously 
described embodiments the differential pressure across the valve assembly 
1b required to lift the valve member 15b is thereby reduced. Because the 
intermediate groove 47 and the relief grooves 48 are on the valve seat or 
mating surface 6b, conventional poppet valve members 15b without grooves 
thereon may be utilized with this embodiment for improved operation in 
fluid moving structures. 
It is anticipated that other alternative configurations could successfully 
utilize the present invention with the same inherent advantages. For 
example, in the further modified valve assembly 16 the relief groove 48 on 
the valve seat or mating surface 6b could communicate with the inlet 
passage 5b instead of the outlet passage 12b as is shown in FIG. 5. Also, 
the intermediate groove could be positioned on one mating surface and the 
relief groove or grooves positioned on the other mating surface whereby 
the inermediate and relief grooves would cooperate to communicate fluid 
therebetween to facilitate opening the valve assembly when the valve 
member is in its closed position. It is further foreseen that various 
combinations and numbers of relief grooves 38 and intermediate grooves 37 
could be utilized according to the present invention. 
FIGS. 6, 7 and 8 illustrate a plate valve assembly 51 utilizing the present 
invention. A seat structure 52 includes an inner surface 53 and an outer 
surface 54 with inlet passages or ports 55 extending therebetween. Valve 
seat or mating surfaces 56 surround the inlet passages or ports 55 on the 
inner surface 53. A cage structure 58 is secured to the seat structure 52 
by a suitable threaded stud 59 with a washer 60 and a nut 61 adjacent an 
outer cage surface 63. A fluid flow outlet passage 64 is defined between 
the inner seat surface 53 and an inner cage surface 62. A plurality of 
concentric circular valve plates 65 are mounted within the outlet passage 
64. The valve plates 64 have mating surfaces 66 thereon adapted for 
engaging the valve seat or mating surfaces 56 whereby contact areas 67 are 
defined therebetween when the valve assembly 51 is in a closed position. 
The cage structure 58 has a plurality of bores 70 extending from and 
generally perpendicular to the inner cage surface 62. Each bore 70 has an 
elongated helical spring 71 therein with a first end 72 engaging a 
respective valve plate 65 and a second end 73 engaging a bore end portion 
69. The elongated helical springs 71 urge valve plates 65 associated 
therewith into seating engagement with respective valve seat or mating 
surfaces 56. 
The several contact areas 67 have generally coaxial circular configurations 
as is shown in FIG. 6. When the valve assembly 51 is in a closed position 
each of the contact areas 67 has a first peripheral portion 75 adjacent a 
respective inlet passage or port 55 and a second peripheral portion 76 
adjacent the outlet passage 64 (FIG. 8). As with the poppet valve 
assemblies previously described, substantial contact areas 67 are 
desireable in the plate valve assembly 51 to distribute the impact upon 
closing of the valve plates 65 and thus reduce wear and increase the 
serviceable lives thereof. 
A concentric intermediate groove 77 is provided on each valve seating face 
56 between the first and second peripheral portions 75 and 76 respectively 
of each contact area 67. A plurality of relief grooves 78 extend radially 
outwardly across each of the valve seating faces 56 from first ends 79 
opening into respective intermediate grooves 77 and past the second 
peripheral portions 76 of respective contact areas 67 to second ends 80 
opening into the outlet passage 64 when the valve seat or mating surfaces 
56 engage the valve plate mating surfaces 66 and the valve assembly 51 is 
closed (FIG. 6). The relief grooves 78 are adapted for communicating fluid 
from the outlet passage 64 to the respective intermediate groove 77 and 
thus to the respective contact areas 67 to exert a lifting force against 
the valve plates 65 and to, facilitate breaking a cohesive force or seal 
which occurs between the mating surfaces 56 and 66 at respective contact 
areas 67. 
In operation as an intake valve in a piston type compressor (not shown), 
the valve plates 65 are in seating engagement as shown in FIG. 7 when the 
plate valve assembly 51 is in a closed position. A pressure differential 
across the plate valve assembly 51 is then created by decreasing the fluid 
pressure in the outlet passage 64 until the fluid pressure in the inlet 
passages 55 is sufficient to overcome the combined forces of the outlet 
passage pressure, the springs 71 and the cohesion or seal at the contact 
areas 67. The valve plates 65 are thereby lifted from seating engagement 
with the respective valve seat or mating surfaces 56 and fluid is allowed 
to flow from the inlet passages 55 to the outlet passage 64. The resulting 
fluid movement through the plate valve assembly 51 thereby reduces the 
pressure differential across same sufficiently to allow the helical 
springs 71 to reciprocate the valve plates 65 to seating engagement with 
their respective valve seats or mating surfaces 56 and close the valve 
assembly. 
In operation as an exhaust or discharge valve, the valve plates 65 are in 
their closed position as shown in FIG. 6 and the compressor piston (not 
shown) pressurizes fluid in the inlet passages 55 until the pressure 
differential across the plate valve assembly 51 is sufficient to lift the 
valve plates 65 and allow fluid to flow therethrough until the helical 
springs 71 reciprocate the valve plates 65 and the valve assembly 51 is 
closed in the same manner as above described. It has been found that by 
communicating fluid by means of the intermediate grooves 77 and the relief 
grooves 78 from the outlet passage 64 to the contact areas 67 that a lower 
pressure differential across the plate valve assembly 51 is required to 
lift the valve plates 65 to an open position. The fluid moving structure 
will thereby operate more effeciently and move equal amounts of fluid as 
compared to conventional structures with the expenditure of less energy. 
Also, because of the lower pressure required in the inlet passages 55 and 
the outlet passage 64 to reciprocate the valve plates 65, the compressed 
fluid will be moved at a lower temperature with a further resultant 
increase in compressor efficiency. 
Because the cohesion between the mating surfaces is operably lessened by 
the relief grooves 78, substantially larger contact areas 67 may be 
employed as compared to conventional structures of this type, thereby 
better distributing the impact on closing of the valve plates 65 and in 
turn reducing the wear on the valve plates 65 for longer serviceability 
thereof. The relief grooves 78 are particularly effective when used in 
combination with coaxial intermediate grooves 77 as shown, because the 
intermediate grooves 77 expose the fluid admitted by respective relief 
grooves 78 to greater portions of the contact areas 67 to exert lifting 
firce against the valve plates 65. 
FIG. 9 shows a modified embodiment generally designated 51a of the plate 
valve assembly 51 as shown in FIGS. 6, 7 and 8. Elements of the modified 
embodiment of the valve assembly 51a which are otherwise substantially the 
same as the previously described device 51 are represented by the same 
corresponding reference numerals except for the addition of the suffix "a" 
to the numerals of the modified structure. 
The plate valve 51a includes a seat structure 52a with an inlet passage 55a 
therethrough and a valve plate 65a shown in a closed position whereby a 
contact area 67a is defined. The relief groove 82 communicates fluid from 
the inlet passage 55a to the intermediate groove 77a and the contact area 
67a, unlike the plate valve assembly 51 wherein the relief grooves 78 open 
into the outlet passage. Because the fluid pressures in the inlet passage 
must exceed those in the outlet passage for the valve to open, equivalent 
relief grooves 82 of the modified valve assembly 51a will communicate 
fluid to the intermediate grooves 77a and the contact areas 67a under 
greater pressure than in the plate valve assembly 51. The required fluid 
pressure differential will be accordingly lower and, although both plate 
valve embodiments represent an improvement over conventional plate valves, 
the modified structure 51a is believed by applicant to be the more 
efficient. 
As with the poppet valve assembly 1 and the modified embodiments thereof, 
1a and 1b, other alternative configurations of the plate valve assemblies 
51 and 51a could successfully utilize the present invention with the same 
inherent advantages. For example, the relief grooves and intermediate 
grooves could be on the plate valve mating surfaces as opposed to the 
valve seats on the seat structure. Further, intermediate grooves could be 
on one of the mating surfaces and the relief grooves on the other mating 
surface whereby the respective relief and intermediate grooves would 
cooperate to communicate fluid to the contact areas when the valve plates 
are in seating engagement in their closed positions. 
In either a plate or a poppet valve assembly, the relief grooves are 
particularly effective with an intermediate groove because the 
intermediate groove exposes the fluid admitted by the relief grooves to a 
greater portion of the contact area. The amount of contact area exposed to 
the fluid may be further increased by positioning the intermediate groove 
adjacent one of the contact area peripheral portions and leaving only a 
"line" or "knife edge" contact between the valve member and valve seat to 
seal against fluid flow when the valve assembly is closed. Fluid may 
thereby be communicated further into the contact area to exert a lifting 
force against the valve member and to facilitate breaking the cohesion or 
seal at the mating surfaces. 
While the cohesive forces present at the contact areas between the mating 
surfaces of the different embodiments have been described as being 
associated with a vacuum like seal or molecular attraction, it is forseen 
that the relief means of applicants' invention would be useful for 
operably reducing other forces associated with surface engagement and 
thereby facilitating the disengagement of such objects. 
It is to be understood that while certain forms of this invention have been 
illustrated and described it is not to be limited thereto except insofar 
as such limitations are included in the following claims.