US4587850A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Arrangement for determining the travel of a piston
Assignee: ZF Boge GmbH
•
Filing: 1984-09-24
•
Granted: 1986-05-13
•
Expires: 2004-09-24
Abstract
Abstract An arrangement for determining and measuring the position or travel of a piston in a cylinder, e.g., suspension component such as a vibration damper, gas-spring or hydropneumatic suspension, uses a structure having no moving electrical contacts, nor any movable electrical leads. The arrangement measures a variable impedance, e.g., a capacitance which is created by first and second electrodes formed within the suspension component and is distinguished in that the electrodes are fixed and are immovable with respect to each other. Capacitance variation is achieved, for example, by allowing a dielectric medium, such as a ceramic or epoxy resin cylinder to enter between two electrodes, the extent of the entry of the dielectric medium being made to be proportional to the relative travel of the piston in the cylinder. In a variation, an additional electrode forming a fixed reference capacitance with the first electrode is provided. The fixed reference capacitance is used together with the measured variable capacitance in a measuring bridge, e.g., Wheatstone bridge, so that undesirable effects of varying temperature and pressure on the capacitances inside the suspension component are compensated during measurement. By virtue of the fact that all the electrodes are fixed relative to one another, the conductive leads from the fixed electrodes can be made immovable relative to each other, whereby measurement problems owing to improper leads and connections are eliminated.
Inventors
- 👤 Bernd Moser
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 16:48
CPC Classifications
F; F15; F15B; F15B15/00; F15B15/20; F15B15/28; F15B15/2815; F15B15/2861; G; G01; G01B; G01B7/00; G01B7/02; G01D; G01D5/00; G01D5/12; G01D5/14; G01D5/24; G01D5/241; G01D5/2412
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
168 words
A damping cylinder in a vibration damper, said cylinder having an arrangement for measuring relative travel of a piston in said cylinder, comprising: a supporting member housing a first electrode which is mounted substantially fixed but substantially electrically insulated with respect to the supporting member; a second electrode spaced from the first electrode to define a space therebetween, said second electrode being substantially fixed with respect to the first electrode said first and second electrodes in use forming a capacitative reactance; a reactance varying member which is mounted to move in accordance with said relative travel between the pistion and the cylinder, said reactance varying member being so disposed that its movement changes the capacitance between said first and second electrodes in accordance with said relative movement between the piston and the cylinder; and electrical connecting means connected to said fixed first and second electrodes for measuring the capacitance formed therebetween and for producing in use a signal indicative of relative movement between the piston and the cylinder.
Claim 2
Dependent Claim
168 words
A damping cylinder in a vibration damper, said cylinder having an arrangement for measuring relative travel of a piston in said cylinder, comprising: a supporting member housing a first electrode which is mounted substantially fixed but substantially electrically insulated with respect to the supporting member; a second electrode spaced from the first electrode to define a space therebetween, said second electrode being substantially fixed with respect to the first electrode said first and second electrodes in use forming a capacitative reactance; a reactance varying member which is mounted to move in accordance with said relative travel between the pistion and the cylinder, said reactance varying member being so disposed that its movement changes the capacitance between said first and second electrodes in accordance with said relative movement between the piston and the cylinder; and electrical connecting means connected to said fixed first and second electrodes for measuring the capacitance formed therebetween and for producing in use a signal indicative of relative movement between the piston and the cylinder.
Claim 3
Dependent Claim
39 words
The damping cylinder in said vibration damper, said cylinder having an arrangement according to claim 1 wherein said reactance varying member is made of a substantially electrically insulating material which on entering said space, acts as a dielectric medium.
Claim 4
Dependent Claim
25 words
The damping cylinder in said vibration damper, said cylinder having an arrangement according to claim 2 wherein said reactance varying member comprises a ceramic tube.
Claim 5
Dependent Claim
28 words
The damping cylinder in said vibration damper, said cylinder having an arrangement according to claim 2 wherein said reactance varying member comprises a tube made of epoxy resin.
Claim 6
Dependent Claim
29 words
The damping cylinder in said vibration damper, said cylinder having an arrangement according to claim 2, wherein said reactance varying member of insulating material includes an electrically conductive coating.
Claim 7
Dependent Claim
47 words
The damping cylinder in said vibration damper, said cylinder having an arrangement according to claim 1 wherein said first and second electrodes are tubular and substantially coaxial, and wherein said supporting member comprises a hollow piston rod which is substantially coaxial with said first and second electrodes.
Claim 8
Dependent Claim
78 words
The damping cylinder in said vibration damper, said cylinder having an arrangement according to claim 1 wherein said cylinder is filled with a dielectric fluid so as to fill said space, and wherein said reactance varying member at least partly displaces said dielectric fluid upon entering said space, whereby said capacitive reactance is a sum of a first capacitive reactance formed by the electrically insulating reactance varying member, and a second capacitive reactance formed by said dielectric fluid.
Claim 9
Dependent Claim
64 words
The damping cylinder in said vibration damper, said cylinder having an arrangement according to claim 1 wherein the reactance varying member comprises electrically conductive material and wherein the cylinder is filled with a dielectric fluid to fill said space, whereby, the reactance varying member upon entering said space partly displaces said dielectric fluid, thereby reducing the measured capacitance between the first and second electrodes.
Claim 10
Dependent Claim
154 words
A damping cylinder in a vibration damper, said cylinder having an arrangement for measuring relative travel of a piston in said cylinder, comprising: a supporting member in the form of a hollow piston rod and housing having fixed first and second spaced substantially coaxial tubular electrodes which are both substantially electrically insulated from the supporting member and mounted in a substantially fixed relationship with respect to each other to form a substantially annular gap; electrical leads connected to said first and second electrodes, said first and second electrodes in use forming a variable capacitance; a sleeve-like member which is mounted for movement reflecting said relative travel of the piston in said cylinder, said sleeve-like member being disposed to enter said substantially annular gap to vary in use said capacitance between said first and second electrodes; and said variable capacitance producing in use a signal indicative of relative travel of said piston in said cylinder.
Claim 11
Dependent Claim
154 words
A damping cylinder in a vibration damper, said cylinder having an arrangement for measuring relative travel of a piston in said cylinder, comprising: a supporting member in the form of a hollow piston rod and housing having fixed first and second spaced substantially coaxial tubular electrodes which are both substantially electrically insulated from the supporting member and mounted in a substantially fixed relationship with respect to each other to form a substantially annular gap; electrical leads connected to said first and second electrodes, said first and second electrodes in use forming a variable capacitance; a sleeve-like member which is mounted for movement reflecting said relative travel of the piston in said cylinder, said sleeve-like member being disposed to enter said substantially annular gap to vary in use said capacitance between said first and second electrodes; and said variable capacitance producing in use a signal indicative of relative travel of said piston in said cylinder.
Claim 12
Dependent Claim
23 words
The damping cylinder in said vibration damper, said cylinder having an arrangement according to claim 9 wherein said sleeve-like member comprises insulating material.
Claim 13
Dependent Claim
24 words
The damping cylinder in said vibration damper, said cylinder having an arrangement according to claim 10 wherein said sleeve-like member comprises a ceramic sleeve.
Claim 14
Dependent Claim
79 words
The damping cylinder in said vibration damper, said cylinder having an arrangement according to claim 10 wherein said cylinder is substantially filled with a fluid having dielectric properties so as substantially to fill said space, and wherein said reactance varying member at least partly displaces said dielectric fluid upon entering said space, whereby said capacitance becomes a combination of a first capacitance formed by the electrically insulating reactance varying member, and a second capacitance formed by said dielectric fluid.
Claim 15
Dependent Claim
29 words
The damping cylinder in said vibration damper, said cylinder having an arrangement according to claim 10, wherein said reactance varying member of insulating material has an electrically conductive coating.
Claim 16
Dependent Claim
27 words
The damping cylinder in said vibration damper, said cylinder having an arrangement according to claim 9 wherein said sleeve-like member comprises a sleeve made of epoxy resin.
Claim 17
Dependent Claim
90 words
The damping cylinder in said vibration damper, said cylinder having an arrangement according to claim 14 wherein said cylinder is substantially filled with a fluid having dielectric properties so as substantially to fill said space, and wherein said reactance varying member at least partly displaces said dielectric fluid upon entering said space, whereby said capacitance becomes a combination of a first capacitance formed by said first and second electrodes and said sleeve-like member, and a second capacitance formed by said dielectric fluid in association with said first and second electrodes.
Claim 18
Dependent Claim
158 words
An arrangement for measuring relative travel of a piston in a damping cylinder of a vibration damper for a mechanical suspension assembly for a vehicle, comprising: a hollow piston rod housing first and second, substantially coaxial tubular electrodes which are spaced from one another and which are both substantially electrically insulated from the piston rod and mounted in a substantially fixed relationship with respect to each other to form a substantially annular gap, said first and second electrodes forming a variable capacitance; a sleeve-like member which is mounted for movement reflecting said relative travel of the piston in said cylinder, said sleeve-like member being disposed to slidingly enter said substantially annular gap to vary said variable capacitance; a third electrode substantially electrically insulated from both the first and second electrodes and spaced from the second electrode to form a substantially fixed reference capacitance in use; and electrical connecting means connected to said fixed first, second and third electrodes.
Claim 19
Dependent Claim
158 words
An arrangement for measuring relative travel of a piston in a damping cylinder of a vibration damper for a mechanical suspension assembly for a vehicle, comprising: a hollow piston rod housing first and second, substantially coaxial tubular electrodes which are spaced from one another and which are both substantially electrically insulated from the piston rod and mounted in a substantially fixed relationship with respect to each other to form a substantially annular gap, said first and second electrodes forming a variable capacitance; a sleeve-like member which is mounted for movement reflecting said relative travel of the piston in said cylinder, said sleeve-like member being disposed to slidingly enter said substantially annular gap to vary said variable capacitance; a third electrode substantially electrically insulated from both the first and second electrodes and spaced from the second electrode to form a substantially fixed reference capacitance in use; and electrical connecting means connected to said fixed first, second and third electrodes.
Claim 20
Dependent Claim
38 words
The arrangement for measuring relative travel of a piston in a damping cylinder of a vibration damper for a mechanical suspension assembly for a vehicle according to claim 16 wherein said sleeve-like member comprises an epoxy resin sleeve.
Claim 21
Dependent Claim
37 words
The arrangement for measuring relative travel of a piston in a damping cylinder of a vibration damper for a mechanical suspension assembly for a vehicle according to claim 16 wherein said sleeve-like member comprises a ceramic cylinder.
Claim 22
Dependent Claim
37 words
The arrangement for measuring relative travel of a piston in a damping cylinder of a vibration damper for a mechanical suspension assembly for a vehicle according to claim 16 wherein said sleeve-like member comprises a metallic cylinder.
Claim 23
Dependent Claim
57 words
The arrangement for measureing relative travel of a piston in a damping cylinder of a vibration damper for a mechanical suspension assembly for a vehicle according to claim 16 wherein said mechanical suspension assembly comprises a liquid dielectric filled and sealed assembly, whereby said sleeve-like member by its movement displaces said liquid dielectric from said annular gap.
Claim 24
Dependent Claim
74 words
The arrangement for measuring relative travel of a piston in a damping cylinder of a vibration damper for a mechanical suspension assembly for a vehicle according to claim 16 wherein an electrical measuring bridge connected to at least said first, second and third electrodes to measure said variable capacitance to produce a signal, by using said fixed capacitance as a reference, said signal indicating the extent of movement of said piston in said cylinder.
References Cited (Backward Citations)
DE1248959B
Cited
US2978638A
Cited
DE1299432B
Cited
DE1933640A1
Cited
US3805150A
Cited
US3833094A
Cited
US4107975A
Cited
DD136069A5
Cited
US4206401A
Cited
DE3212433A1
Cited
GB2106651A
Cited
DE3244891A1
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-05-12 | 1989-11-11 | 1990-05-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-05-12 | 1993-11-11 | 1994-05-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-05-12 | 1997-11-11 | 1998-05-13 | $7700.00 | Window Closed / Lapsed |