Fluid handling – Self-proportioning or correlating systems – Supply and exhaust type
Reexamination Certificate
1999-09-30
2001-03-06
Hepperle, Stephen M. (Department: 3753)
Fluid handling
Self-proportioning or correlating systems
Supply and exhaust type
C137S112000, C192S003570
Reexamination Certificate
active
06196252
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to a shuttle valve for a hydraulic circuit and, more particularly, to a shuttle valve for hydraulic circuit which allows drainage back through the shuttle valve.
BACKGROUND OF THE INVENTION
Shuttle valves for multi-path hydraulic circuits are used to provide fluid pressure from several passages entering the shuttle valve to one passage exiting the shuttle valve. For instance, in 3-way hydraulic circuits in automatic transmissions, shuttle valves are used to supply transmission fluid into a first passage exiting the shuttle valve from either a second or a third passage entering the shuttle valve. The shuttle valve ensures that transmission fluid provided by the second passage is supplied to the first passage without leaking back out through the third passage. Likewise, if fluid is supplied by the third passage, the shuttle valve ensures that this fluid is supplied to the exiting first passage and not back out through the second passage. While shuttle valves employed in this fashion suitably channel fluid into the appropriate passage, several drawbacks exist when this type of valve is used in conjunction with clutch elements on automatic transmissions.
In automatic transmissions, transmission fluid is many times required to be supplied to one clutch element from different sources. As disclosed in U.S. patent application Ser. No. 09/283,567, filed on Apr. 1, 1999, and assigned to the assignee of the present application and hereinafter incorporated by reference, a transmission fluid circuit contains an OD clutch element which is actuated either by a manual shift valve or a electronic solenoid valve. As such, a 3-way shuttle valve can be used to supply transmission fluid pressure from either of these sources to the OD clutch element. This valve ensures that pressure supplied through the OD solenoid valve is provided to the OD clutch element and does not leak back through the manual shift valve. Likewise, the 3-way shuttle valve ensures that fluid pressure supplied from the manual shift valve is supplied to the OD clutch element and does not leak back through the OD solenoid valve.
However, it is important that transmission fluid contained within the OD clutch element is allowed to leak back through the shuttle valve when the OD clutch element ceases to be applied. This leak back ensures that the clutch element is released and does not, instead, burn up due to frictional engagement of rotating elements within the transmission. To provide for this leak back, hydraulic pressure from the OD clutch element pushes the slider valve either toward the passage leading from the manual shift valve or the OD solenoid valve, thereby sealing one of these two passages. The passage remaining open provides the conduit for fluid to leak back from the OD clutch element.
However, if the slider valve is positioned directly under the exiting passage to the OD clutch element, hydraulic force from the clutch element is unable to push the slider valve in either direction. As a result, transmission fluid is trapped in the OD clutch element, thereby maintaining the OD clutch element in an engaged state. The present invention was developed in light of this drawback.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a shuttle valve having a slider valve which will allow drainage of fluid back through the shuttle valve even if the slider valve is positioned directly under the exiting passage.
To achieve these and other objects, the present invention provides a shuttle valve for a multipath hydraulic circuit comprising a valve body having a main passage extending along an axis and having a uniform inner periphery. The valve body has a first passage intersecting the inner periphery of the main passage at a first intersection area. The first intersection area has an intersection length extending parallel to the axis. The valve body has a second passage intersecting the inner periphery of the main passage at a second intersection area. The second intersection area is positioned away from the first intersection area in a direction parallel to the axis. The valve body has a third passage intersecting the inner periphery of the main passage at a third intersection area. The third intersection area is located away from the first intersection area and positioned on an opposite side of the first intersection area from the second intersection area. The shuttle valve further has a slider valve positioned within the main passage which has a first section adjacent and attached to a second section. The first section has a first outer periphery substantially similar to the inner periphery of the passage such that the first section of the slider valve and the main passage substantially prevent fluid flow therebetween. The first outer periphery extends a predetermined length parallel to the axis and which is shorter than the intersection length. The second section has a second outer periphery with a recessed portion being recessed from the outer periphery of the main passage such that fluid is able to pass between the second section and the inner periphery of the main passage. As a result, fluid is able to pass from the first passage and around the slider valve and to the second passage or the third passage.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are intended for purposes of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
REFERENCES:
patent: 2610859 (1952-09-01), Wilcox
patent: 3338257 (1967-08-01), Ferguson
patent: 3850274 (1974-11-01), McLean
patent: 3963383 (1976-06-01), Hill
patent: 3996965 (1976-12-01), Peters
patent: 4121499 (1978-10-01), Hay
patent: 4217934 (1980-08-01), Peters
patent: 4250795 (1981-02-01), Martinic
patent: 4253481 (1981-03-01), Sarlls, Jr.
patent: 4261451 (1981-04-01), Strong
patent: 4324311 (1982-04-01), Farris
patent: 4485876 (1984-12-01), Speller
patent: 4592382 (1986-06-01), Rubin et al.
patent: 4736965 (1988-04-01), Smith
patent: 4819609 (1989-04-01), Tippmann
patent: 4843920 (1989-07-01), Hayasaki et al.
patent: 4850192 (1989-07-01), Mitsumasa et al.
patent: 4852663 (1989-08-01), Hunt
patent: 4856549 (1989-08-01), Ueno
patent: 5163474 (1992-11-01), Rizk
patent: 5234031 (1993-08-01), Pickett et al.
patent: 5297860 (1994-03-01), Nakamura
patent: 5299859 (1994-04-01), Tackett et al.
patent: 5682791 (1997-11-01), Liesener
Botosan Valentin
Martin Berthold
Streetman Charles K.
DaimlerChrysler Corporation
Fuller III Roland A.
Hepperle Stephen M.
LandOfFree
Shuttle valve for a multipath hydraulic circuit with bypass... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Shuttle valve for a multipath hydraulic circuit with bypass..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Shuttle valve for a multipath hydraulic circuit with bypass... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2516477