Brakes – Internal-resistance motion retarder – Valve structure or location
Reexamination Certificate
1999-02-24
2001-11-06
Oberleitner, Robert J. (Department: 3613)
Brakes
Internal-resistance motion retarder
Valve structure or location
C188S266600
Reexamination Certificate
active
06311812
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a device for realizing an opening and/or closing function in terms of its force/velocity curves. The device is of the type which comprises two parts working away from and towards each other, at different velocities and accelerations. Examples of the said working parts can be cone and seat, slide and housing, etc. The said working parts work with a stroke and determine, in dependence upon the present stroke sizes, the passage of a fluid by way of a restrictor function realized by the parts. At least the one part, e.g. the cone, slide, etc., is subjected to force on both its sides.
The invention is also assignable to a device for achieving in a pressure regulator or pressure-limit valve an opening or closing process between two parts working away from and towards each other and which work with a stroke and determine, in dependence upon the present stroke size, the passage of a fluid by way of a restrictor function realized by the parts, in which at least the first part is subjected to force such that pressure regulation is realizable by means of equilibrium between the obtaining regulator force and the corresponding cumulative force, e.g. realized by one or more springs, flow forces, pilot pressure forces, etc.
The invention also relates to an application of at least two series-connected restrictors in a device which realizes an opening and/or closing function in terms of its force-velocity curves. The application is effected in a device comprising two parts which work away from and towards each other at different velocities and accelerations and which work with a stroke and determine, in dependence upon the sizes of the strokes, the passage of a fluid by way of a restrictor function realized by the parts and in which the one part is subjected to force on both its sides.
In purely general terms, the invention can be assignable to various types of governor valves for shock absorbers intended for use in vehicles. The new device and the application can specifically be used in shock absorbers which are intended to form part of wheel suspension systems for vehicles (cars, motor cycles, etc.)
The invention relates primarily to valves which are used to control pressure, i.e. to generate shock-absorption forces/shock-absorption pressure as a function of the shock absorber strokes and piston velocities/flows. The said shock absorber forces and shock absorber strokes constitute an energy absorption function for controlling or monitoring wheel motions and chassis motions.
PRIOR ART
Reference is made, inter alia, to the following
FIGS. 1
,
2
and
5
. Valves (governor valves) which are currently used in shock absorbers normally utilize a pressure-controlling device (denoted as
1
in
FIG. 5
) equipped, for example, with shims, cone or plate, which form a main restrictor (
2
in FIG.
5
). The pressure control is achieved with the aid of force equilibrium between the regulator force
3
, i.e. the regulator pressure force on the one hand, and supplementary forces
4
, i.e. spring force, flow force, valve-damping force, friction force and, in certain cases, pilot pressure force on the other hand. Depending on the level in the flow force and the spring force level, the pressure control can be carried out with different governor characters (
5
in FIG.
1
), i.e. a certain increase in force as a function of the increase in velocity (piston velocity). Such types of arrangement are designated in hydraulic terms as pressure regulators.
The pressure regulator in question has a pronounced opening point (
6
in FIG.
1
), at which the governor valve, during a shock absorber acceleration, is about to open or close the pressure control facility as a function of velocity. Before the point, at low velocities, the pressure is dependent only upon a fixed restrictor or restrictors (
7
in FIG.
5
), which give rise to a leak or bleed curve (
8
in FIG.
1
). This restrictor function is often designated as “bypass”.
Normal pressure regulators for shock absorbers are constructed with the aid of preselected leak curves and governor characters.
Account of the Invention
TECHNICAL PROBLEM
In conventional shock absorbers and valve constructions, for example, there are difficulties in adapting the adjustment of the damping character of the shock absorber to a small bleed and flat/plane governor character. Rough or jerky functioning is unavoidable in these cases. There is a need to be able to obtain smooth shock absorber behaviour in the shock absorbers in question given different types of adjustments. The invention solves this problem.
The change in force level at the pronounced opening point (“blow-off point”) always causes vibrations whenever the shock absorber shifts between positive and negative velocities, i.e. changes between compression (C in
FIG. 1
) and expansion (R in FIG.
1
). The lower the said “by pass” level the more accentuated becomes this behaviour in those cases in which the pressure regulator has to be constructed with a flat governor character, i.e. has to have a low increase in damping force combined with increased velocity. Valves of this type produce a pronounced roughness or jerkiness whenever the shock absorber is working. The invention sets out to solve this problem also.
There are traditional ways of smoothing the roughness and the jerkiness. The most common and easy method is to use soft rubber springing between the shock absorber and the chassis. This method, like other similar methods, of finding a solution to the raised problem gives rise to unwanted springing (
9
in
FIG. 2
) of the damping force. This problem can be seen with the aid of, for example, a diagram showing the damping force relative to the velocity during cycles between compression and expansion. In connection herewith, it is also apparent that the roughness and jerkiness are transformed into unwanted damped vibrations (
10
in
FIG. 2
) in the rubber springing, which thus constitutes an insulation problem. The invention solves these problems also.
The vibrations which arise in the opening and closing processes in conventional valves have to be damped inside the valve in order to avoid undamped or stationary oscillations. Such inner dampings provoke, in turn, an inertia in the valve, which inertia produces delays and greater amplitude in the damped oscillations. The invention solves these problems also.
In valves of this kind, the problem arises of making the valves more seal-tight at higher modulation levels. Likewise, there may be a requirement to alter the curves in the static velocity and force diagram by means of a simple adjustment procedure. There is also a need in certain cases to avoid tolerance sensitivities. In one embodiment it is also important, especially in the opening function, to be able to prevent a tendency for the fluid to adhere to a surface or surfaces of the cone and/or seat. The invention solves these problems also.
It is important that the problems in question can be solved by intrinsically technically simple means. The invention solves this problem also.
THE SOLUTION
What can primarily be considered characteristic of a device of the type first named above is that the said restrictor function is made up of at least two part-restrictors which can be simultaneously actuated by a respective stroke and thereupon vary, preferably successively, their restrictor sizes differently from each other in dependence upon the respective stroke size in order in the restrictor function to give rise to a passage of fluid which produces a smooth curve shape in the introductory or concluding part of the respective opening or closing function.
In refinements of the device, the two part-restrictors are each related to their own governor area and the governor areas differ in size. The governor areas are arranged so as to alter their sizes in dependence upon the sizes of the common stroke and the part-restrictors mutually vary their sizes in dependence upon how quickly the areas of the part-restrictors grow or diminish as a function of the common stroke. In a furthe
Lindholm Martin
Malmborg Håkan
Sonsterod Lars
Connolly Bove & Lodge & Hutz LLP
Oberleitner Robert J.
Ohlins Racing AB
Williams Thomas J.
LandOfFree
Device and application involving two parts working away from... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Device and application involving two parts working away from..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Device and application involving two parts working away from... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2618599