Spring devices – Vehicle – Comprising compressible fluid
Reexamination Certificate
1998-10-27
2001-03-13
Oberleitner, Robert J. (Department: 3613)
Spring devices
Vehicle
Comprising compressible fluid
Reexamination Certificate
active
06199838
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to gas springs and more particularly to filler valves for gas springs.
BACKGROUND OF THE INVENTION
Gas springs may be utilized to yieldably resist movement of a body, such as a clamping ring for a metal blank of a die in a press for forming sheet metal parts. The springs are generally constructed with an actuating rod connected to a piston slidably received in a cylinder having a chamber charged to a predetermined pressure with an inert gas, such as nitrogen. This provides a spring effect or cushion permitting the rod to yieldably move towards its retracted position when a force applied externally to the rod exceeds the opposing force produced by the gas in the chamber acting on the piston. The gas springs can be operated with an external source of gas or can be pre-charged and operated as a self-contained unit.
A valve received in a gas fill passage through the cylinder selectively communicates the chamber filled with pressurized gas with the exterior of the cylinder. The valve permits the compressed gas to be removed from the chamber when desired, enables the addition of compressed gas to the chamber and prevents the gas from leaking from the chamber when it is desired to maintain the pressurized gas in the chamber. Conventional valves used with gas springs have an intricately shaped body with a generally frusto-conical or tapered side wall portion which is constructed to mate with a complementary frusto-conical tapered portion of the gas fill passage in the cylinder to provide a seal between the valve and the cylinder to prevent leakage of the gas from the chamber. Due to the small size of conventional filler valves and the intricately shaped gas fill passage required with these valves, it is extremely difficult to accurately machine the gas fill passage to provide a sufficient seal between the tapered portions of the valve and the cylinder. Further, any scratching or scuffing of the tapered portion on the valve body or in the fill passage compromises or destroys the seal between them and requires replacement of the valve or the entire cylinder body.
Additionally, conventional valves have a threaded brass swivel which is rotatable relative to the valve body to permit the swivel to be rotatably received in complementary threads in the gas fill passage while the valve body is slidably engaged with the interior of the gas fill passage, substantially without rotation of the valve body, to prevent damage to the valve body as it is assembled into the fill passage. The brass swivel is fragile and can be over-torqued when the filler valve is assembled into the gas fill passage thereby jamming or distorting the brass swivel such that the filler valve cannot be removed from the fill passage without damaging it. Further, the brass swivel has a small number of very small threads which may be easily damaged or stripped when assembled into the fill passage, thereby destroying the valve and making it very difficult, if not impossible, to remove the filler valve from the fill passage.
SUMMARY OF THE INVENTION
A gas spring has a casing defining a chamber constructed to be filled with a gas under pressure, a piston rod received in the chamber for reciprocation between extended and retracted positions and having a free end projecting beyond the casing, a gas fill passage formed in the casing and through which pressurized gas is admitted into the chamber and a filler valve disposed in the fill passage to selectively permit the flow of gas through the fill passage. The filler valve has a body with a passage formed therethrough, a valve seat defined in the passage between opposed ends of the body and a poppet received in the passage and engagable with the valve seat to selectively permit gas flow through the filler valve and hence, through the fill passage of the gas spring casing. The filler valve body preferably has mechanical threads formed in its exterior and constructed to be mated with complementary threads in the gas fill passage to firmly and releasably hold the filler valve within the fill passage. Preferably, an O-ring carried by the valve body provides a gas-tight seal between the valve body and the fill passage within a generally cylindrical portion of the fill passage. The valve body preferably has one or more integral tabs which retain the poppet within the valve body in assembly.
The poppet preferably has a valve stem extending through the valve seat at least when the poppet is in its closed position and a valve head integral with the valve stem and constructed to engage the valve seat to prevent the flow of gas through the filler valve when the poppet is closed Preferably, an O-ring is disposed between the valve head and the valve seat to improve the seal between them. Also preferably, the poppet has an end portion extending from the valve head opposite the valve stem and constructed to project the beyond the valve body at least when the poppet is in its open position to engage a wall of the fill passage to limit the travel of the poppet towards its open position. The poppet is generally loosely received within the passage of the valve body and is normally in an open position. The pressure of the gas in the chamber of the gas spring exerts a force on the poppet moving the poppet to its closed position with the valve head firmly engaged with the valve seat to prevent the flow of gas through the filler valve. To open the filler valve, the valve stem is displaced from the opposite side of the valve seat to displace the valve head from the valve seat. With the poppet in its open position, gas may be removed or added to the chamber of the gas spring as desired.
Objects, features and advantages of this invention include providing a gas spring with a filler valve which has very few parts, has integral, durable threads, is larger than conventional valves to facilitate machining of the passage in which the valve is received, does not require an intricate passage to provide a seal between the filler valve and the gas spring, is rugged, reliable, durable, easy to assemble into and remove from a gas spring and of relatively simple design, economical manufacture and assembly.
REFERENCES:
patent: 2862515 (1958-12-01), Breichle
patent: 4016900 (1977-04-01), Shipp et al.
patent: 4792128 (1988-12-01), Holley
patent: 5172892 (1992-12-01), Wallis
patent: 5275387 (1994-01-01), Cotter et al.
patent: 3031026 (1982-03-01), None
patent: 19520192 (1996-12-01), None
patent: 0282626 (1988-09-01), None
patent: 2190478 (1987-11-01), None
Diebolt International, Inc.
King Bradley
Oberleitner Robert J.
Reising Ethington Barnes Kisselle Learman & McCulloch
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