Brakes – Internal-resistance motion retarder – With means for locking parts together temporarily
Reexamination Certificate
1999-12-29
2001-03-27
Graham, Matthew C. (Department: 3613)
Brakes
Internal-resistance motion retarder
With means for locking parts together temporarily
C188S382000, C188S322150, C297S362120
Reexamination Certificate
active
06206153
ABSTRACT:
BACKGROUND OF THE INVENTION
Locking gas springs are well known and widely used in applications in which a member is moved by a spring force to a selected position and locked in that position. Perhaps the most well-known and common use of locking gas springs is in the seat support columns of office chairs. When most or all of the user's weight is off the seat and a control lever is moved to a release position, the spring force extends the spring and raises the seat. When the user sits on the seat and the gas spring is released, the user's weight overcomes the gas spring force, thus compressing the spring and lowering the seat. The user can adjust the seat to any desired height and by releasing the control lever when the desired height has been attained lock the seat in the desired position. Locking gas springs can be used for other adjustable installations, such as hospital beds, various forms of work tables and stands, and adjustable vehicle seat backs, such as for motor vehicles and aircraft.
Safety standards for the seat backs of motor vehicles and aircraft are readily met by locking gas springs used in tandem, that is, a locking gas spring on each side of the seat back. The necessity for tandem installations arises from the need to carry the very high forces imposed on the seat back in a crash, such as the rearward forces that occur when a motor vehicle is rear-ended and the seat occupant is forced back against the seat back by inertial forces or during the rebound phase of a front end collision when the occupant is forced back against the seat back by a restraint system. The tandem use of locking gas springs in vehicle applications requires synchronous control of the two springs by means of relatively costly control linkages.
SUMMARY OF THE INVENTION
One object of the present invention is to provide an adjustable installation, such as a vehicle seat back, that uses gas springs in tandem but does not require linking them, thus eliminating costly and complicated components. Another object is to provide an installation, especially for use in vehicles, in which two gas springs are locked and thus able to sustain the high forces that may be imposed on them in a crash. Yet a further object is to provide a gas spring that normally functions as a non-locking gas spring but that locks when a high force is imposed on it or is caused to lock by the sensing of a high acceleration of the installation in which it is used.
The foregoing objects are attained, in accordance with one aspect of the present invention, by an adjustable installation comprising a body and a member carried by the body for adjustment among a plurality of positions by movements substantially in tandem of two spaced-apart locations on the member. A controllable locking gas spring is coupled between the body and the member at one of the locations, and an emergency locking gas spring is coupled between the body and the member at the other of the locations. The emergency locking gas spring normally acts like a non-locking gas spring and is thus in a follower relationship to the controllable locking gas spring but is locked automatically in either of two ways, depending on its design. The term “follower relationship” is used herein to mean that the emergency locking gas spring (1) extends and exerts a spring force when the controllable locking gas spring is released and extends and (2) is compressed when the controllable gas spring is released and is compressed by an external force applied to the installation. In some designs of the emergency locking gas spring, the emergency locking gas spring locks when a force greater than a predetermined force is imposed on it. In other designs, the emergency locking gas spring is locked in response to a signal generated by, an acceleration detector upon detection of an acceleration of the installation greater than a predetermined acceleration.
An emergency locking gas spring for an installation according to the present invention will include a cylinder, a body of liquid in the cylinder, a rod piston movably received in the cylinder in sealed relation and having a bypass through which the liquid flows upon movement of the piston, and a system for preventing liquid from flowing through the bypass in the event of an emergency that could cause the movable member to move under a high force against the restraint of the emergency locking gas spring. Suitable systems for closing the bypass in an emergency include: a valve that is normally open to allow liquid flow through the bypass but closes when a force in excess of a predetermined force is applied to the rod piston; a quantity of an electro-rheological liquid contained in the cylinder and a detector and energization installation responsive to an acceleration of the installation in excess of a predetermined acceleration for energizing the liquid to increase its viscosity such as to substantially prevent the liquid from flowing through the bypass; a quantity of a magneto-rheological liquid contained in the cylinder and a detector and energization system for sensing acceleration of the installation in excess of a predetermined acceleration and imposing a magnetic field on the liquid to increase its viscosity such as to substantially prevent the liquid from flowing through the bypass.
In some embodiments of systems using a valve to close the bypass, the valve is a member that normally is in clearance from a port of the bypass to allow liquid flow through the bypass when the piston moves under a force less than a predetermined force but is movable into sealing relation to the port by a force due to hydrodynamic pressure imposed on the valve member when the force on the piston exceeds the predetermined force. Such a valve member may be of elastomeric material and is shaped and dimensioned to deform and close the bypass under a high hydrodynamic pressure. With such a valve, a high force imposed on the piston in an emergency produces a high acceleration of the piston, thus producing a high hydrodynamic pressure that acts on the valve member such as to close it.
Another suitable valve member is a member of an elastomeric material having walls defining a passage that forms at least a portion of the bypass, the walls and passage being shaped and dimensioned such that the walls collapse and close the passage in response to liquid flow through the passage at a velocity in excess of a predetermined velocity. In particular, the walls may define a passage having a variable cross-sectional area, the area increasing in the direction of the liquid flow to which the valve responds by closing. In such a design, the increase in the area in the direction of flow produces a zone of reduced pressure within the passage which, along with the high pressure outside the walls of the passage, causes the walls to collapse and close the passage.
In preferred embodiments, the emergency locking gas spring includes a cylinder having a closed end and an open end, a piston rod having a portion received in the cylinder and a portion extending out of the cylinder through the open end, and a seal package received in the open end of the cylinder in sliding and sealed relation to the piston rod and sealed and fixed relation to the cylinder and defining within the piston member a closed chamber. A rod piston is affixed to the portion of the piston rod within the chamber and has a piston seal in sliding and sealed relation to the cylinder and defining in the chamber a closed end section and an open end section, each of a volume that varies in accordance with the position of the rod piston axially of the cylinder. A floating piston received in the open end section in sliding and sealed relation to the cylinder and the piston rod defines in the open end section a gas part between the seal package and the floating piston and a liquid part between the floating piston and the rod piston. A body of liquid, such as oil, is contained in the closed end section and the liquid part of the open end section. A body of gas under pressure substantially above atmospheric pressure is c
Baker & Botts L.L.P.
Fichtel & Sachs Industries, Inc.
Graham Matthew C.
Sy Mariano
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