US3542438A - Control valve - Google Patents

Description

United States Patent Edward J. Falk St. Louis, Missouri April 7, 1969 Nov. 24, 1970 Wagner Electric Corporation Newark, New Jersey a corporation of Delaware [72] Inventor [21 1 Appl. No. 22] Filed [45] Patented 73] Assignee [54] CONTROL VALVE 16 Claims, 2 Drawing Figs. [52] US. Cl...l 303/84, 188/151, 200/82, 340/52 [51] Int. Cl B60t- 17/22 [50] Field ofSearch 137/(O- Dea); 200/82, 82.1, 82.2, 82.3, 82.31; 340/52, 52C; 188/151, 151.11, 152, 152.02; 303/84, 84A; 60/54.5E

[56] References Cited UNITED STATES PATENTS 3,463,554 8/1969 Bueler 200/82X 3,469,889 9/1969 Bueler 188/151X 3,475,573 10/1969 Maltais et a1. 200/82 3,480,333 11/1969 Stelzer 188/151X Primary Examiner-Milton Buchler Assistant Examiner-John J. McLaughlin, Jr. Attorney-Joseph E. Papin ABSTRACT: A control valve or driver-warning mechanism for use in a split-braking system and having a single centering piston for effecting automatic centering of the switch actuating piston when subjected to the fluid pressures of said split system subsequent to the correction of a failure of the fluid pressure in one of said split systems.

Patented Nov. 24, 1970 3,542,438

FIG. 2

INVENTOR EDWARD J. FALK CONTROL VALVE This invention relates in general to split-braking systems and in particular to control valves for indicating fluid pressure failure in one of said split systems.

In the past, a single centering piston was-utilized in conjunction with a shiftable piston to effect automatic centering thereof when subjected to separate fluid pressures, as shown in (1.8. Pat. No. 767,732 issued Aug. 16, 1904, to R. C. Bromley. One of the disadvantageous features of such past constructions was the undesirably greater number of points of close concentricity inherent between the housing bores, shiftable piston and centering piston design of such past constructions. Another disadvantageous feature of such past constructions was that the separate seals on the shiftable piston and the centering piston necessitated a longer housing to accommodate the separate sealing between said pistons. Further, another disadvantageous feature of such past constructions was that separate seals were employed on the shiftable and centering pistons which also necessitated separate retaining means therefor.

The principal object of the present invention is to provide a control valve which overcomes the aforementioned disadvantageous or undesirable features, and this, as well as other objects and advantageous features of the present invention, will become apparent hereinafter.

Briefly, the invention embodies a control valve having a housing with switch-actuating means movable therein from a normally centered position toward opposed translated positions and defining with said housing opposed chambers for subjection to separate fluid pressures, other means movable in one of said chambers for engagement with an abutment on said housing and in said one chamber and including means movable in said switch-actuating means for engagement therewith, said other means being responsive to fluid pressure in said one chamber to arrest movement of said switch-actuating means toward said one chamber.

In the drawings wherein like numerals refer to like parts wherever they occur:

FIG. 1 is a sectional view showing a control valve embodying the present invention in cross section; and

FIG. 2 is a fragmentary view taken from FIG. 1 illustrating an alternative construction also embodied in the present invention incross section.

Referring now to FIG. 1, a control valve or warning mechanism 1 is provided with a housing 2 having a bore 3 therein alined with stepped counterbores 4, 5 and 6, said counterbores 4,5 and 5, 6 defining annular shoulders or abutments 7 and 8 therebetween on said housing, respectively. Closure members or end plugs 9, 10 are threadedly received in the open ends of the housing bore 3 and counterbore 6, and fluid pressure ports l1, 12, which are adapted for connection with separate fluid pressure generating chambers of a tandem or split system master cylinder (not shown), are provided in the housing 2 intersecting with said housing bore and counterbore 3, 6 adjacent to the closure members 9, 10, respectively. A cross-bore and cross-counterbore 13, 14 are also provided in the housing 2, said cross-bore intersecting with the housing counterbore 4 and said cross-counterbore being threaded at its open end to threadedly receive an electrical switch, indicated generally at 15 (to be discussed in detail hereinafter).

A reciprocal switch actuating member or piston 16 is shown in its centered or normal operating position in the housing 2 having spaced opposed annular flanges or end portions l7, l8 slidably disposed in the housing bore and counterbore 3, 5, respectively, and a peripheral seal 19 is disposed in the flange 17 in sealing engagement with said housing bore. The sealing engagement of the seal 19 with the bore 3 defines an effective cross-sectional area A, which is subjected to fluid pressure in a chamber 20 defined in said bore between the closure member 9 and the flange l7 and in open pressure fluid communication with the port 11 at all times. The piston 16 is also provided with a switch-positioning portion or land 21 which is positioned beneath the housing cross-bore 13 when said piston. is in its centered position (as shown), and peripheral cam faces 22, 23 are provided on said piston on opposite sides of said land. The piston flange 18 is provided with opposed abutment and sealing surfaces 24, 25, and a blind bore 26 is axially provided through the sealing surface 25 having an end wall or abutment 27 on said piston flange.

A motion-arresting member or centering piston, indicated generally 28, is provided with stepped extensions 29, 30 having a seal retainer or positioning shoulder 31 therebetween, and the smaller stepped extension 29 is slidably received in the piston blind bore 26 having a free end or abutment 32 thereon for abutting and driving engagement with the piston end wall 27. A seal or O-ring 33 is disposed in sealing engagement between the housing counterbore 5, the piston flange sealing surface 25, and the periphery of the smaller extension 29, and said seal is maintained in said housing counterbore against dis placement by the seal positioning shoulder 31 of the centering piston 28. The larger stepped extension 30 extends coaxially through the housing counterbore 5 being radially spaced therefrom, and a radially extending head portion 34 is integrally formed with said larger extension. The head portion 34 is axially movable in the housing counterbore 6 being radially spaced therefrom, and an annular shoulder or abutment 35 is defined on said centering piston 28 between the larger extension 30 and said head portion for engagement with the housing shoulder 8. Another abutment surface 36 is provided on the head portion 34 opposed to the shoulder 35 for engagement with the interior end or abutment portion of the closure member 10, and a plurality of cross-passages 37 are provided across the periphery of said head portion to facilitate pressure fluid communication between the housing counterbores 5, 6 past the centering piston 28.

It should be noticed that the sealing engagement of the seal 33 between the housing counterbore 5 and the periphery of the centering piston smaller extension 29 defines an effective area A which is smaller than and opposed to the area A,, and another area A, is provided on the centering piston 28 being substantially defined by the sealing engagement of said seal about the periphery of the smaller extension 29. The area A, is less than the area A, and greater than the area A and when the centering piston 28 is drivingly engaged with the switch piston 16, the area A, is additive to the area A said additive areas A A being greater than the area A, as discussed in detail hereinafter. The areas A A, are subjected to fluid pressure in a chamber 38 defined in the housing counterbores 5,6 between the closure member 10 and the centering piston 28 and seal 33, and said chamber is connected in pressure fluid communication with the port 12 at all times.

The switch 15, as previously mentioned, includes a conductive closure or plug member 40 threadedly and conductively received in the housing cross-counterbore l4, and a metal terminal 41 extends through said plug member being insulated therefrom, said terminal having an exterior end for connection in an electrical circuit of a type well known in the art for selectively energizing a driver warning or dash lamp (not shown). A nonconductive switch member 42 is slidably received in a bore 43 provided in said plug member 40, said switch member having a lower end or follower portion 44 extending through the housing cross-bore 13 for engagement with the piston land 21 and having a conductive contact 45 on the upper end portion thereof for electrical engagement with another contact 46 on said plug member. To complete the description of the control valve 1, a current-carrying spring 47 is interposed between the interior end of the terminal 41 and the switch member contact 45 urging the follower portion 44 of the switch member 42 into positioning engagement with the piston land 21.

In the operation with the component parts of the control valve 1 positioned as shown in FIG. 1 and as described hereinabove, independent or separate fluid pressures P,, P normally having substantially equal magnitudes are supplied upon operator actuation of the split system-type master 3 Y cylinder (not shown) to the ports 11, 12 and chambers 20, 38, respectively, of said control valve. The fluid pressure P, in the chamber 20 acts on the effective area A, of the switch piston to establish a rightwardly directed force P, A, tending to urge said piston from its centered position toward a rightwardly displaced or translated position in the housing 2. The fluid pressure P in the chamber 38 acts on the effective area A, of the switch piston 16 establishing a force P, A, in opposition to the force P, A,, and the fluid pressure P also acts on the effective area A,, of the centering piston 34 creating a force P, A,, urging said centering piston leftwardly to engage the shoulder 35 thereof with the housing shoulder 8 and drivingly engage the abutment end 32 thereof with the piston wall 27. The force P, A,, is transmitted to the housing 2 and is thereby ineffective to cause translatory movement of the piston 16 in the leftward direction toward its translated position, and since the area A, is less than the area A,,the force P, A, is less than the force P, and A, and is therefore also ineffective to cause-translatory movement of the switch piston 16 toward its leftward translated position; however, since the additive areas A,, A,, are greater than the area A,, the additive forces P, A, and P A,, are greater than the opposing force P, and ,A, thereby arresting or preventing trans-latory movement of the switch piston 16 toward its rightward translated position. in view of the foregoing, it is apparent that when the separate fluid pressures P,, P are substantially equal, the switch piston 16 is maintained in its centered position, as shown in FIG. 1, against leftward or rightward displacement toward its opposed leftward or rightward translated positions.

in the event of the failure of the fluid pressure P,, the force P, A, is, of course, eliminated, and the force P A, is unopposed and effective to-move the switch piston 16 leftwardly toward its leftward translated position wherein the abutment surface 24 of the piston flange 18 is moved into abutting en gagement with the housing shoulder 7. The leftward displacement movement of the switch piston 16 into its leftward translated or disabled position also moves the piston land 21 thereof leftwardly toward a position disengaged from the follower end 44 of the switch operating member 42. The force of the switch spring 47 thereafter drives the operating member 42 downwardly moving the follower end 44 thereof into the housing counterbore 4, and the downward movement of said operating member also engages the contact 45 thereon with the switch contact 46 energizing the switch 15 to complete its electrical circuit and lighta dash lamp (not shown) for warning the vehicle operator that a portion of his brake system has failed. When the defect inthe brake system has been repaired so that the fluid pressure P, is reestablished to substantially the same magnitude ofthat ofthe fluid pressure P the force P, A, is also reestablished and is thereafter effective to drive the switch piston 16 rightwardly toward its original or centered position to disengage the piston flange surface 24 from the housing shoulder 1 and reengage the end wall 27 of the'flange 18 with the abutment 32 of the centering piston 28. As mentioned hereinbefore, the additive forces P, A, and P, A,, are greater than force P, A, and in opposition thereto to obviate centering movement of the switch piston 16 in response to the reestablished force P, A 1 past its centered position and thereby maintain said switch piston in its centered position. Of course, when the switch piston 16 is so recentered in response to the reestablished force P, A,, the cam face 23 of said switch piston is drivingly engaged with the follower end 44 of the switch member 42 urging said switch member upwardly against the switch spring 47 toward its original position disengaging the contacts 45, 46 and reengaging said follower end with the switch piston land 21.

Alternatively, in the event ofthe failure of the fluid pressure P, when the component parts ofthe control valve 1 are in their centered or normal positions, the forces P, A, and P A are, of course, eliminated, and the force P, A, is unopposed and effective to concertedly move the switch and centering pistons 16, 28 rightwardly toward their rightward translated position wherein the abutment surface 36 of said centering piston is moved into abuttingengagement with the interior end of the closure member 10. The rightward displacement movement of the switch and centering pistons 16, 28 toward the rightward translated position also moves the piston land 21 rightwardly toward a position disengaged from the follower end 44 of the switch-operating member 42. The force of the switch spring 47 thereafter drives the operating member 42 downwardly moving the follower end 44 thereof into the housing counterbore 4, and the downward movement of said operating the switch and centering pistons 16, 28 leftwardly toward their original or centered positions to disengage the centering piston abutment 36 from the closure member 10 and reengage the centering piston shoulder 35 with the housing shoulder 8. As previously mentioned, since the additive areas A,,, A,, are greater than the area A,, the reestablished additive forces P A and P, A, are also greater than the opposing force P, A, and are thereby effective to drive the centering piston 16 from its rightward translated position toward its centered position; however, the engagement of the centering piston shoulder 35 with the housing shoulder 8 transfers the force P A,, to the housing 2, and since the force P A2 is less than the opposing force P, A,, further recentering movement of the switch piston 16 in response to only the reestablished force P, A past its centered position is obviated. Of course, when the switch piston 16 is so recentered in response to the reestablished forces 1, A and P, A,, the cam face 22 of said switch piston is drivingly engaged with the follower end 44 of the switch member 42 urging said switch member upwardly against the switch spring 47 toward its original position disengaging the contacts 45, 46 and reengaging the follower end with the switch piston land 21.

It should be noted that the axial length L of the larger stepped extension 30 on the centering piston 28 between the shoulders 31, 35 thereof is predeterminately greater than the distance or'stroke through which the switch piston 16 and said centering piston move from their centered or normal operating positions toward their rightwardly translated position; therefore, the seal positioning shoulder 31 is always positioned within the housing counterbore 5 to positively retain the seal 33 against displacement therefrom into the housing counterbore 6 and thereby maintain the sealing integrity of said seal between the housing counterbore 5, the switch piston surface 25 and the periphery of the centering piston extension 29.

Furthermore, it should also be noted that only the concentricities between the housing bore and counterbore 3, 5 and between the piston flanges 17, 18 slidable therein are critical wherein very close tolerances are manifest, whereas the construction of the centering piston 28 avoids further concentricity problems. For instance, the concentricity between the piston bore 26 and the periphery of the piston flange 18 is not a critical tolerance sincethe centering piston extension 29 is supported by the resilient O-ring 33, and the concentricity between said extension 29and the extension 30 and head 34 of the centering piston .28 are, of course, obviated due to the radial spacing thereof from the housing counterbores 5,6.

Referring now to FIG. 2, an alternative construction is shown wherein the closure member 10 is provided with a blind bore 50 therein connecting with and being substantially coaxial with the housing counterbore 6. The end wall 51 of the blind bore 50 providesa seat on the closure member to form one end of a spring 52, arid the other end of said spring is engaged with the abutment surface 36 of the centering piston 28 to normally urge the shoulder 35 thereof toward engagement with the housing shoulder 8. The strength of the spring 52 is preferably rather small and should not be greater than the force needed to translate the switch piston 16 and centering piston 28 against the inherent friction thereofin the housing 2.

From the foregoing, it is now apparent that a novel control valve 1 meeting the objects and advantageous features set forth hereinbefore, as well as others, is provided and that changes as to the precise configurations, shapes and details of the construction set forth in the disclosure by way of illustration may be made by those skilled in the art without departing from the spirit of the invention.

lclaim:

l. A control valve comprising a housing having a pair of op posed chambers therein for respective connection with the separate fluid pressures of a split master cylinder, switch-actuating means movable in said housing from a normally centered position toward opposed translated positions and including opposed portions defining opposed differential areas for subjection to the separate fluid pressures in said chambers, respectively, and said switch-actuating means being urged in the direction of one of said chambers toward one of its translated positions in response to the separate fluid pressures acting on said opposed differential areas, abutment means on said housing in said one chamber, and other means for arresting said switch-actuating means in its centered position against movement to its. one translated position including piston means movable in said one chamber, extension means on said piston means movable in one of said portions defining the smaller of said differential areas in said one chamber and having a free end for engagement with said switch-actuating means, other abutment means on said extension means for engagement with said first-named abutment means, and a third area on said extension means for subjection to one of the separate fluid pressures in' said one chamber and additive to said smaller differential area, said other abutment means and said free end being respectively urged toward engagement with said first-named abutment means and said switch-actuating means to prevent movement of said switch-actuating means toward its one translated position in response to the one fluid pressure acting on said third area.

2. A control valve according to claim 1, comprising sealing means sealably engaged between said housing, said one portion, and said extension means in said one chamber, respectively, third abutment means on said housing and in said one chamber defining the one translated position of said switchactuating means, said switch-actuating means being responsive to the other of the separate fluid pressures acting on the larger of said differential areas in the event of the failure of the one separate fluid pressure to concertedly move said other means in the direction ofsaid one chamber into engagement with said third abutment means, and means on said other means for engagement with said sealing means to predeterminately limit the movement thereof in the direction of said one chamber.

3. A control valve according to claim 1, wherein said one chamber includesa pair of stepped bores, said one portion being movable in the smaller of said stepped bores, sealing means sealably engaged between said one portion, said smaller stepped bore, and said extension means, respectively, third abutment means on said housing in the larger of said stepped bores, said switch-actuating means being responsive to the other ofthe'separate fluid pressures acting on the larger of said differential areas in the event of the failure of the one separate fluid pressure to concertedly drive said piston means in the direction of said one chamber into engagement with said third abutment means, and means on said extension means for engagement with said sealing means to prevent the displacement thereof from sealing engagement with said smaller stepped bore upon the actuation of said piston means into engagement with said third abutment means.

4. A control valve according to claim 1, comprising a bore in said one portion and facing said one chamber, said extension means being slidable in said bore, and means on said switch-actuating means defining an end wall of said bore for engagement with said free end ofsaid extension means.

forces or resistances 5. A control valve according to claim 4, wherein said one chamber includes apair of stepped bores having a shoulder therebetween defining said first named abutment means, said one portion being slidable in the smaller of said stepped bores, sealing means sealably engaged between said smaller stepped bore, said one portion, and said extension means, third abutment means on said housing in the larger of said stepped bores, said switch-actuating means being responsive to the other of the separate fluid pressures acting on the larger of said differential areas in the event of the failure of the one separate fluid pressure to drivingly engage said end wall with said extension means free end and concertedly drive said piston means into engagement with said third abutment means, and retaining means on said piston means and movable in said smaller stepped bore for engagement with said sealiny means to prevent the displacement thereof from said smaller stepped bore into said larger stepped bore upon the actuatior ofsaid piston means into engagement with said third abutment means.

6. A control valve according to claim 1, comprising resilient means engaged with said piston means and urging said other abutment means toward engagement with said first-named abutment means, said resilient means exerting a force on said piston means no greater than that necessary for overcoming the friction forces inherent between said switch-actuating means and said housing.

7. A control valve comprising a housing having a bore therein alined with a pair of stepped counterbores, a shoulder on said housing between said stepped counterbores, a pair of ports in said housing intersecting with said bore and the larger of said stepped counterbores and adapted for connection with the separate fluid pressures of a split master cylinder, respectively, a first piston movable in said housing between said ports from a normally centered position toward opposed translated positions including a pair of opposed end flanges respectively slidable in said bore and the smaller of said opposed counterbores, a first effective area on one of said end flanges slidable in said bore for subjection to one of the separate fluid pressures, a second effective area on the other of said end flanges slidable in said smaller stepped counterbore and opposed to said first area for subjection to the other of said separate fluid pressures, said first area being predeterminately greater than said second area, another bore in said other end flange facing said stepped counterbores and having an end wall defined on said other end flange, said first piston being urged from its centered position toward one of its opposed translated positions in response to the one and other separate fluid pressures respectively acting on said first and second areas, means for arresting said first piston in its centered position against movement toward its one translated position including a second piston movable in said stepped counterbores, a first extension on said piston means slidable in said other bore, a free end on said first extension in said other bore for engagement with said end wall, a head portion on said piston means movable in said larger stepped counterbore and having opposed abutment surfaces thereon, one of said opposed abutment surfaces being for engagement with said housing shoulder, a second stepped extension on said piston means between'said head portion and first extension, and another shoulder on said piston means between said first and second extensions, an O-ring seal sealably engaged between said first extension, said smaller stepped counterbore, and said other end flange and defining said second area on said other end flange, the sealing engagement of said O-ring on said first extension also defining a third effective area on said piston means for subjection to the other separate fluid pressure and additive to said second area, said one abutment surface and said free end being respectively urged into engagement with said housing shoulder and said end wall in response to the other fluid pressure acting on said third area to prevent the movement of said first piston toward its one translated position, and abutment means in said larger stepped counterbore and predeterminately axially spaced from said housing 7. shoulder to define theone translated position of said first piston, said first piston being responsive to the one separate fluid pressure acting on said first area in the event of the failure of the other separate fluid pressure to drivingly engage said end wall with said free end and concertedly drive said piston means to engage the other of said opposed abutment surfaces with said'abutment means, and the axial distance between said other shoulder and said one abutment surface being predetermined to maintain said other shoulder within said smaller stepped bore for engagement with said O-ring to prevent the displacement thereof from said smaller stepped eounterbore into said larger stepped eounterbore upon the concerted actuation of said first and second pistons to engage said other abutment surface with said abutment means.

8. A control valve comprising a housing, means movable in said housing and defining therewith opposed chambers for respective subjection to separate fluid pressures, opposed differential areas on said means respectively subjected to the separate fluid pressures in said chambers, said means being urged to ward one of said chambers in response to the separate fluid pressures respectively acting on said opposed differential areas, a pair of abutment means on said housing and said first named means, respectively, and other means movable in said one chamber for engagement with one of said abutment means and including means movable in said firstnamed means for engagement with the other of said abutment means, said other means being urged into engagement with said one abutment means and said included means being with said other abutment means in response to the separate fluid pressure in said one chamber acting on said other means to arrest movement of said firstnamed means toward said one chamber.

9. A control valve according to claim 8, wherein the larger of said differential areas is subjected to the separate fluid pressure in the other of said chambers to urge said first-named means toward said one chamber in opposition to the separate fluid pressure in said one chamber acting on the smaller of urged into engagement said differential areas, and a third area'on said other means for subjection to the separate fluid pressure in said one chamber and additive to said smaller differential area, said other means being urged into engagement with said one abutment means and said included means being urged into engagement with said other abutment means to arrest the movement of said first-named means toward said one chamber in response to the separate fluid pressure. in said one chamber acting on said third area.

10. A control valve according to claim 9, wherein said smaller differential area and said third area are at least as great I as said larger differential area.

l1.'A control valve according to claim 8, comprising a third area in said other means for subjection to the separate fluid pressure in said one chamber, said other means being urged into engagement with said one abutment means and said included means being urged into engagement with said other abutment means to arrest the movement of said first-named means toward said one chamber in response to the separate fluid pressure in said one chamber acting on said third area.

12. A control valve according to claim 8, comprising a bore in said first-named means facing said one chamber and having a wall portion defining said other abutment means. and said included means defining extension means on said other means, said extension means being movable in said bore and having a free end for engagement with said wall portion.

13. A control valve according to claim 12. comprising-an end portion on said first-named means facing said one chamber, said bore extending through said end portion, sealing means in said one chamber engaged between said extension means and said housing for seating engagement with said end portion and defining the smaller of the opposed differential areas.

14. A control valve according to claim 13. wherein the sealing engagement of said extension means with said sealing means defines a third area on said other means for subjection to the separate fluid pressure in said one chamber and additive to said smaller differential area, the separate fluid pressure in said one chamber acting on said third area to establish a force urging said other means and said extension means toward engagement with said one and other abutment means, respec tively, and additive to the force of the separate fluid pressure in said onechamber acting on said sealing means to arrest the movement of said first-named means toward said one chamber in response to the opposing force of the separate fluid pressure in the other of said chambers acting on the larger of said opposed differential areas.

15. A control valve according to claim 14, wherein the additive magnitudes of said smaller differential area and said third area are greater than that of said larger differential area.

16. A control valve according to claim 13, wherein said extension means includes retainer means for engagement with said sealing means to limit displacement thereof from seating engagement with said end portion toward said one chamber.

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