Brakes – Internal-resistance motion retarder – Having a thrust member with a variable volume chamber
Reexamination Certificate
1998-12-11
2001-04-24
Oberleitner, Robert J. (Department: 3613)
Brakes
Internal-resistance motion retarder
Having a thrust member with a variable volume chamber
C188S322190
Reexamination Certificate
active
06220408
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a spring-and-damper unit for installation between a vehicle body and a wheel guidance part of a motor vehicle. More specifically, the present invention relates to a spring and damper unit including a vibration damper and a spring, wherein the vibration damper has a piston rod having a piston which runs in a cylinder and divides the cylinder into a first working space surrounding the piston rod and a second working space remote from the piston rod. The vibration damper further includes a storage space arranged outside of the cylinder hydraulically connected to the second working space and serves as a compensation space for the piston rod volume moving into and out of the cylinder.
2. Description of the Related Art
A prior art vibration damper is disclosed in reference DE 42 33 701 A1. This reference discloses a storage device and/or compensation space arranged outside of a cylinder of the vibration damper and in which a gas space is separated from a fluid space in the interior of the storage space by a diaphragm. An embodiment with a second compensation space also exists. This type of vibration damper is designed to combine the advantages of a two-pipe vibration damper with those of a one-pipe vibration damper, to achieve a vibration damper with improved damping properties. However, the separating element between the gas space and the fluid space in the storage device is essential in this type of vibration damper to prevent the gas from going into solution in the damping fluid and to thus preclude the formation of a gas cushion in one working space. This is needed to ensure a correct response by the vibration damper even in the event of small strokes.
Another type of prior art vibration damper is disclosed, for example, in references DE 28 21 492 A1 and DE 28 55 561 A1. These spring-and-damper units include a spring or compensation space located outside of a cylinder of a vibration damper with a diaphragm between the gas filling and the damping fluid filling in the spring or compensation space. An embodiment with a spring space whose gas filling is separated from the damping fluid filling by a separating piston is also described. Such spring-and-damper units are used for the suspension and damping of the rear wheel in motorcycles and are installed between the rear wheel rocker arm and the frame so that the units do not have to absorb any wheel guidance forces.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a spring-and-damper unit arrangeable within a predetermined installation space in a motor vehicle that has the greatest possible supporting length for the piston rod in the cylinder and, in addition, is subject to low bending moment of the parts axially movable relative to each other so that the spring-and-damper unit can absorb wheel guidance forces, and has a simple and economical overall structure.
This object is attained by the present invention in that a storage device is connected to a spring plate on which a carrying spring of the spring-and-damper unit rests. The spring plate is arranged in a pressure-tight fashion on a cylinder or a container surrounding the cylinder of the vibration damper. The interior of the cylinder or the container is hydraulically connected to the storage device via a connecting channel in the spring plate. This arrangement in which the storage device is located outside the cylinder or container and is connected to the spring plate permits full utilization of the installation length available to support the piston rod so that a relatively great supporting length for the piston rod in the cylinder is ensured even when the spring-and-damper unit is in the rebound state. Because such spring-and-damper units usually must absorb wheel guidance forces, the large supporting length of the piston rod prevents the parts axially movable relative to each other from jamming, and thus ensures high functional reliability and good response behavior of the spring-and-damper unit. Moreover, the extra function of the spring plate as accommodating the storage device and forming the connecting channel to the interior of the vibration damper, a simple and economical overall structure is attained.
The smallest possible bending moment is exerted by the wheel guidance forces on the relatively-moving parts of the spring-and-damper unit when the spring-and-damper unit is attached as close to the vehicle wheel as possible. Mounting of the spring-and-damper unit in close proximity to the vehicle wheel is possible in the inventive device because the spring plate is connected to the storage device to form a structural and assembly unit and because the storage device is located on the side of the vibration damper away from the vehicle wheel. The spring plate is seated above the tire so that the cylinder or container of the vibration damper may be installed in the vehicle at a very close proximity to the tire.
In a further embodiment, the spring plate has an interior embodied as the storage device and preferably formed by two shells, which are produced, for example, as stamped or pressed parts from steel sheet. Moreover, according to a further feature of the invention, an advantageous and economical embodiment is obtained by forming a structural and assembly unit with the spring plate, the storage device, and a steering lever. The storage device is connected to the spring plate so that its axis is arranged parallel or somewhat inclined relative to the axis of the vibration damper and so that the storage device wall is located at a slight radial distance from the outer wall of the cylinder or the container.
According to the invention, an especially strong connection between the storage device and the vibration damper is attained by the fact that a bottom of the storage device has a fastening journal connectable with a connecting part of the vibration damper for securely connecting the storage device to the vibration damper. As a result, the storage device is connected at a first connection to the spring plate and at a second connection to the vibration damper.
To permit the deepest possible travel of the piston rod into the cylinder, a bottom valve is usually arranged in the cylinder to be installed in the storage device. In a highly advantageous embodiment, the bottom valve is arranged and secured in the connection cover, thus creating a structural unit that may be checked before being assembled with the other storage device parts.
In a further embodiment, the axis of the storage device is arranged approximately perpendicular to the axis of the vibration damper, whereby the bottom of the storage device is connected with a steering lever. Thus, the storage device can be embodied both as a spring plate and as a steering lever, especially when this combination part is produced in a casting process.
There is great freedom in embodying the storage device. For example, it may be embodied as a separating piston storage device, whereby the storage device wall and the storage device bottom are produced in a single piece, or the storage device wall and the connecting cover may be produced in a single piece with the connecting cover using, for example, an extrusion method. The bottom valve can be arranged in the fluid space of the storage device to permit the deepest possible travel of the piston rod into the cylinder.
The objects of the present invention, which are to provide the greatest possible bearing distance of the piston rod in the cylinder and to provide an installation of the vibration damper in close proximity to the vehicle wheel, is attained in one embodiment by connecting the storage device to the cylinder bottom so that the axis of the storage device is inclined relative to the axis of the vibration damper and a length of the storage device runs by a drive shaft of the vehicle wheel at a distance. Such a design of a spring-and-damper unit or of a vibration damper is especially suitable for motor vehicles with front-wheel drive.
The various features of novelty
Handke Gunther
Pradel Robert
Cohen & Pontani, Lieberman & Pavane
King Bradley
Mannesmann Sachs AG
Oberleitner Robert J.
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