Brakes – Internal-resistance motion retarder – Position of thrust member relative to chamber
Reexamination Certificate
1999-11-10
2002-09-10
Lavinder, Jack (Department: 3613)
Brakes
Internal-resistance motion retarder
Position of thrust member relative to chamber
C188S319100, C188S319200, C188S314000, C188S322130
Reexamination Certificate
active
06446771
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a shock absorber which works with a bleed function. In this connection, the bleed function can interact with a non-return valve function. In certain embodiments, the shock absorber is preferably arranged so as to have both the bleed and the non-return valve functions. The shock absorber is also of the type which has a cylinder and, working in the latter in working medium and arranged on the piston rod, a piston arrangement which comprises at least two first and second pistons arranged at a distance from one another. At least one of said pistons can, in connection with an end position in the cylinder or the shock absorber, be introduced into a first space so as, depending on its position in or at the space, to bring about a modified or varied damping force compared with the case when the piston in question is located outside the space.
STATE OF THE ART
This type of shock absorber is previously known and reference can in this connection be made to inter alia U.S. Pat. No. 3,195,645. The present invention can be seen as a development in relation to this known shock absorber. The known shock absorber comprises a dual-piston arrangement in which the first or front piston enters and exits a cup-shaped container so as to bring about an increased damping force in the shock absorber end position concerned. A second piston of full-size diameter is made with fixed throttles via which the damping forces or damping capacity of the shock absorber can be implemented in positions outside said end positions. The known shock absorber also demonstrates that increased damping force can be obtained in both the end positions of the shock absorber.
Reference can also be made to UK Patent Specification 2 202 921 which indicates that, instead of a cup-shaped part which is arranged in the shock absorber end concerned, use can be made of a pin-shaped element which interacts with a recess in the piston rod end and in this way acts on an arrangement which increases the damping force via the shock absorber end concerned.
Reference can also be made very generally to European Patent Specification 565 832 B1.
It is also known per se to arrange for a bleed function in a shock absorber. What is known as return bleed is used in order to make the wheels of the vehicle follow the surface of the ground better. By arranging a bleed flow past a member which is arranged on the piston in question and acts on the medium, forward, upward and return (downward) movements are made easier. The use of a non-return valve in the return bleed makes possible separation of compression bleed and return bleed to different degrees, which can be selected depending on the non-return valve selected.
DESCRIPTION OF THE INVENTION
Technical Problem
It is desirable to be able, in accordance with said U.S. Patent Specification, to arrange a dual-piston arrangement of the type disclosed also on those types of shock absorber which have on the one hand a cylinder for a piston rod and a dual-piston arrangement in working medium essentially in the form of hydraulic oil, and on the other hand a container for an accumulator function, which is connected to the cylinder via an intermediate part, a hose or a pipe connection etc. In this respect, it is essential to be able to arrange an appropriate bleed function, if appropriate together with a non-return valve function, in the structure so that an integrated construction which functions well is obtained. The invention aims to solve this problem inter alia.
In the use of a bleed or non-return valve function, it is often advantageous to be able to arrange the member performing the bleed function so that regulatability or adjustability can be achieved. It is to be possible to implement this adjustability by means of members known per se in a manner known per se. The invention solves this problem also.
As claimed in the present invention, it is also desirable that dual-piston and bleed and non-return valve arrangements can work with a piston function provided with shims, by means of which a speed-dependent damping force function can be achieved. The invention solves this problem also.
In connection with said UK Patent Specification, the arrangement of a conical pin-shaped element involves a problem associated with being able to use the interior of the piston rod for mounting and positioning members which can effect said bleed and/or non-return valve functions. The invention solves this problem also and indicates a basic structure with a cup-shaped element as claimed in said U.S. Patent Specification or a corresponding arrangement.
In connection with the device or shock absorber as claimed in said UK Patent Specification, there is also a problem associated with being able to clearly and unambiguously separate the functions of the first and second pistons. As claimed in the invention, the first piston is to be capable of effecting its end damping force function without being influenced by the second piston. The invention solves this problem also by proposing a basic concept based on the U.S. Patent Specification.
As claimed in the invention, seat and nozzle functions are to be arranged for effecting said bleed function. The invention solves this problem also and proposes in this connection a unique arrangement for a piston rod, construction and arrangement of the second piston with its associated shims and also construction and arrangement of the first piston on the piston rod.
There is also a requirement to be able to use alternative constructions and functions in connection with the bleed function in a shock absorber of said type with a dual-piston arrangement and shims arranged on the latter. The invention solves this problem also and proposes an alternative or additional arrangement in which the bleed function is separated from or integrated with the non-return valve function.
The Solution
A shock absorber of the type described in the introduction can be considered to be mainly wherein either the piston rod is provided with an inner second space which is arranged so as to accommodate said bleed function and any non-return valve function arranged with the latter, or the second piston is made with a bleed function and any non-return valve function interacting with the latter.
In developments of the inventive idea, it is proposed that said first space is to be arranged in a cup-shaped or sleeve-shaped part which is located in said end position in question in the cylinder or the shock absorber. In this connection, a cup-shaped or sleeve-shaped part can be located in each end position in the cylinder. The first cup-shaped part can then serve the first piston in the first end position, and the second cup-shaped part can serve a third piston in the second end position. Said first and/or third piston can then have a sleeve-shaped part which, in the end position in question, is involved in forming said first space in the end position concerned. An alternative to forming the first space with a cup-shaped part is to make the cylinder wall with a thickened wall in the portion concerned.
In further embodiments, both a member performing the bleed function and a member performing the non-return valve function are arranged in the second space. In this connection, the member performing the bleed function can be arranged so that it can be controlled in order to obtain a bleed function which can be regulated by controls. The second space can also consist of a recess extending in the longitudinal direction of the piston rod, at the first end of which the member performing the bleed function is arranged and in which an operating rod extending in the recess, toward the second end of the recess, is arranged. At said second end, the operating rod can be acted on by means of a wheel or equivalent adjusting member. The member performing the non-return valve function is located outside the member performing the bleed function, that is to say closer to the free end of the piston rod in a case where the outer piston of the piston arrangement or the first piston can be introduced int
Löfgren Oskar
Sintorn Torkel
Connolly Bove & Lodge & Hutz LLP
Lavinder Jack
Öhlins Racing AB
Williams Thomas J.
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