FR2699997A1 - Stroke measuring system for the compression stroke of a shock absorber. - Google Patents

Abstract

a) Stroke measuring system to detect the compression stroke of a shock absorber. b) It is in the form of an ultrasonic stroke measuring system with a permanent magnet (22) constituting one of the components of the system and a magnetostrictive waveguide (26) constituting the other component of the system, the magnet permanent (22) being mounted adjacent to the discharge element (15) integral with the cylinder (10) and the magnetostrictive waveguide (26) being provided along an axial bore (16b) of the element delivery unit by being connected to the measurement electronics and the delivery element (15) is made of a non-magnetic material.

Description

"Race measurement system for the race of com

  The present invention relates to a two-component displacement measuring system which is movable relative to one another and to a measurement electronics associated with each other.

  to detect the compression stroke of an amor-

  weaver, with a cylinder having a closed bottom and a

  movable element of displacement alternately in

  inside the cylinder, in particular in the form of a piston / piston rod assembly which slidably passes through the front wall;

  the cylinder opposite to the bottom of the cylinder, a component of the system being integral with the cylinder and the other component of the system being integral with the discharge element.

  A travel measuring system of this type is known from DE-OS 40 29 633. In this known stroke measuring system, the components of

  system, mobile in relation to each other,

  carry at least one measuring coil attached to the cylinder piston of the damper and at least

  an element of a material influencing the inductance of the measuring coil on each occasion the other part of the piston / cylinder assembly; the element which influences the inductance has a structure marking the posi-

  setting in the direction of relative motion

piston and cylinder.

  According to DE-OS 38 21 569,

  a magnetically operated stroke measuring system

  to-inductive, comparable for the damper compression stroke, describing at the same time capacitive effect and opto-electric effect measuring systems. According to a publication by Balluff Company 7303 Neuhausen (Catalog No. 507 D, edition 9001, page 4), an ultrasonic stroke measuring system is also known (BTL transsonar stroke sensor) In this device a measuring rod is introduced with a magnetostrictive waveguide through the bottom of the cylinder of a piston / cylinder assembly within the cylinder and through the piston of the cylinder; this piston itself carries a permanent magnet serving as

  position detector The use of the measuring system

  sure of ultrasonic stroke according to which in principle the travel time of the torsion waves is measured along a magnetostrictive effect wire, for a high reliability, we reach a high measurement accuracy

  for the cylinder stroke Furthermore, the use of

  tion of an ultrasonic stroke measuring system in the manner described, is not applicable to a shock absorber if

  however, it is possible that at the expense of

  important factors at the piston and / or the

  of the cylinder, it is indeed, in the case of a damping

  generally control and damping valves.

  which completely use the entire volume

  available at this location For the assembly of

  of the system, mobile in relation to

  others in the ultrasonic stroke measuring system

  sounds, we would not have a sufficient place in

  additionally, in the described assembly of system components,

  me for a damper, it would have considerable sealing difficulties Part of the useful surface of the piston would be lost what could not be

  compensated only by larger dimensions of

  However, an increase in the dimensions would result, regardless of the weight

  higher, would not allow the fitting of an amor-

  weaver equipped with a race measuring system

  ultrasound instead of a conventional damper.

  The present invention aims, starting from

  the state of the art and the problems mentioned above.

  above, to perfect a system of measurement of

  of the type defined above for the compression stroke.

  damping in order to achieve accurate, safe measurement results, which are particularly

  independent of thermal influences.

  For this purpose, the invention relates to a device

  corresponding to the type defined above,

  rised in that it is in the form of a measuring system of

  ultrasonic race with permanent magnet constitut

  killing one of the system components and an on-line guide

  magnetostrictive component constituting the other component of the system, the permanent magnet being mounted adjacent to the discharge element integrally with the

  cylinder and the magnetostrictive waveguide being pre-

  seen along an axial bore of the compression element

  by being connected to the measuring electronics and

  the delivery element is made of a non-magnetic material

tick.

  The stroke measuring system according to the in-

  In particular, the invention offers the advantage of being able to use the high measuring accuracy of the ultrasound travel measuring system and its very great independence from thermal influences without increasing the dimensions of the damper compared to those of a conventional damper and without requiring special means to ensure the tightness of the damper.

  According to other advantageous features

  of the invention, in particular, in the

  of the invention, the permanent magnet can be

  protected in the cylinder and preferably adjacent to the front surface of the cylinder opposite the bottom of the cylinder, where there is sufficient space and

  for example by renouncing

  using the gluing of the

mant to the cylinder wall.

  It is also possible in a favorable way

  to develop permanent magnets like ring magnets surrounding the piston rod, in

  particular in the form of annular magnets with several

  poles, to generate at the level of the waveguide at

  magnetostrictive effect, intense magnetic fields

  its, which lead to very strong torsion pulses for an electrical measurement pulse; these pulses move at the speed of ultrasound along the filiform waveguide to a converter

of measurement electronics.

  In addition, it has proved to be advantageous

  mount the converter at the extreme end of the

  the piston rod while at the end

  of the latter is the damping path of the ultrasonic pulses because it is possible to

  this way a measuring path extending practically

  the entire length of the piston rod.

  Drawings. Embodiments of the invention are shown schematically in the drawings in which: FIG. 1 is a longitudinal section of a preferred embodiment of a shock absorber

  equipped with a stroke measuring system according to the invention.

  tion. FIG. 2 is a fragmentary sectional view on an enlarged scale along line 2-2 of FIG. 1. FIG. 3 is a longitudinal section.

  another preferred embodiment of an amorphous

  weaver equipped with a stroke measuring system according to the invention.

  Description of the exemplary embodiments.

  In a detailed manner, FIG. 1 shows a damper comprising a cylinder 10 with a bottom of damper or cylinder 12, closed and a discharge element 15 which in the embodiment consists of a piston 14 and a piston rod 16 Inside the cylinder 10 is thus the piston 14; the piston rod 16 and its free end 16 opposite the piston 14 is projecting from the cylinder 10 A

  the end of the cylinder 10 opposite the bottom 12 of the cy-

  lindre, the piston rod 16 is guided behind the scenes.

  by reciprocating movement in a joint 18 by dipping more or less deeply into the cylinder 10.

  As the drawing indicates by

  when terminated, the piston 14 may comprise, if appropriate, a damping valve 20 which may be electrically adjustable in connection pipes (no

  represented) arriving from the outside through a

axial drilling 16b through.

  The stroke measuring system incorporated in the shock absorber is in the form of an ultrasonic stroke measuring system consisting of a permanent magnet 22

  which, in the exemplary embodiment, is a magnet

  quadrupole ring handle surrounding a piston rod 16 of a non-magnetic material and secured to

  the inside of the cylinder 10 in the vicinity of its end.

  mity opposed to the bottom 12, especially by gluing.

  permanent mantle 22 forms one of the two components of the

  measuring system, moving relative to each other.

  The second component of the system is a rod-shaped subsystem 24 housed in the bore 16b of the piston rod 16 and comprising as main element a

magnetostrictive waveguide 26.

  The waveguide 26 extends axially between

  a damping path 28 and a converter circuit

  weaver 30 at the free end 16a of the piston rod

  your 16; the waveguide 26 is surrounded between the

  min 28 damping and converter mounting

  by a non-magnetic bearing tube 32

  current being used as a measurement pulse supplied to the magnetostrictive waveguide or to a

  electrical line passing through this waveguide of a

  current, gives a circular magnetic field surrounding the waveguide and which, cooperating with the magnetic field or the magnetic fields of the permanent magnets 22 results in a magnetostrictive torsion pulse This pulse moves from the position of the permanent magnet 22 at speed

  ultrasound, on the one hand towards the path of damping

  22 to be absorbed, and on the other hand, it arrives on the converter 30 which transforms it into a

  electrical signal supplied to an electronic

  tation or measurement (not shown) The travel time of the torsion pulse between the position

  of the permanent magnet 22 and the converter 30 con-

  thus a measure of the road traveled by the impulse

  torsion; this time corresponds exactly to the position of the piston 14 in the cylinder 10 As the mounting and operation of an ultrasonic stroke measuring system corresponding to the type envisaged

  are still known and the description will not resume

  not here the structure of the converter and the electro-

  operating network connected by lines 32; 34 to

converter 30.

  According to FIG. 2, the waveguide 26 in

  magnetostrictive is a tubular waveguide 26

  hollow; inside this waveguide we have,

  already indicated, a separate power line 27 forming part of a current loop whose return branch passes as a conductor 27 '(insulated) along the inner wall of the protection tube 32 A current pulse serving as measurement pulse, sent by the power line 27 going to

  inside the ultrasonic waveguide 26, hollow, as-

  sure because of the circular magnetic field that

  is applied, cooperating with at least one

  gnetic created by the permanent magnet 22, a pulse

  of torsion generated by magnetostriction, which is

  the position of the permanent magnet 22, at the ultrasonic speed, is then placed on the one hand towards the damping path 28 to be absorbed and on the other hand to the converter 30.

  torsion converter, transforms the impulse

  ultrasonic wave arriving in the waveguide 26 in

  an electrical signal supplied to the measurement electronics

  In this way, it is possible to measure very precisely the time between the emission of the current pulse in the current loop 27, 27 'and the arrival

  of a torsion pulse thus generated on the con-

  vertisseur 30 It is possible to delete complete-

  the protective tube because the parts

  the measuring system are in any case

  inside the piston rod 16.

  According to Figure 3 of the drawing, the discharge element 15 is made in a manner comparable to the piston rod 16 of the first example of

  production; however, this element has a diameter

  be slightly larger and is not completed by a

  piston guided tightly against the wall

  of the cylinder 10 For the material correspondence

  the outline sketched above, the basic body of the

  The delivery member 15 will be designated by the reference numeral 16 as the piston rod. Correspondingly, the base body bore bears the reference 16b and the upper end the reference 16a. For the other parts of the stroke measuring system according to FIG. FIG. 3 will use the same references as for the corresponding parts of the measuring system of

run of Figure 1.

  As a variant of the first example of

  In the stroke measuring system of FIG. 3, the influence of the damping effect is effected by means of a damping coil, where appropriate.

  adjustable damping coil form or a

  damping valve adjustable in the line 36 from an opening 38 at the lower end of the cylinder 10 to an accumulator 40 in which there is optionally a gas bubble 40a delimited by a membrane allowing a greater or lesser volume of hydraulic fluid to pass from the cylinder

  in the accumulator 40 When the refueling element

  15 enters the cylinder 10, the liquid

  hydraulic pump can pass into the accumulator 40,

  the pressure drop being regulated by the throttle element

  cushioning or valve 20.

  In addition or in replacement, it is possible,

  in the embodiment of FIG.

  the pressure and / or the volume of a fluid of pres-

  inside the cylinder 10 by means of a pump 42 connected to an opening 44 at the lower end

  The pump 42 also allows a

  active part of the shock absorber equipped with the stroke measuring system.

  The above description clearly shows

  that an ultrasonic stroke measuring system

  the type envisaged can be integrated into an amor-

  weaver so that the piston 14 and the bottom 12 of the cylinder

  dre remain available for mounting the damping valves and that the active surfaces of the piston are not diminished by the integration of the stroke measuring system In addition, the permanent magnet 22 can be protected without this causing problems of construction, by integrating it into

  the bore of the cylinder, the subsystem 24 with the guiding

  waveguide 26 being protected inside a piercing of the piston rod which exits conventionally from the

  cylinder and is sealed with respect to the cylinder.

  This makes it possible to use an ultrasonic stroke measurement system, which is very accurate in detecting the race of

  compression of a shock absorber, a system whose accuracy

  sion is practically unaffected by variations in

  considerable temperature

  produce inside a damper.

  It is clear that from the examples of

  described above, those skilled in the art

  many possibilities for modifying and / or completing

  the means available without departing from the

  In particular, it is possible to

  embodiment of the invention, to use the piston rod

  digs itself as a protection tube for the guiding

  this is particularly advantageous for small dampers whose piston rod has a

relatively small diameter.

Claims (2)

R E V E N D I C A T IO N S   1) Two-stroke stroke measuring system   movable speakers relative to each other and a   associated measurement electronics to detect the   compression of a shock absorber, with a cylinder   having a closed bottom and a moderate displacement element   bile alternately by diving inside the cy-   lindre, especially in the form of a pis-   piston rod which slidably traverses the front wall of the cylinder opposite to the   bottom of the cylinder, a component of the system being   cylinder and the other component of the system   being integral with the element of repression,   in that it is in the form of an ultrasonic stroke measuring system with a permanent magnet (22) constituting one of the components of the system and a guide   magnetostrictive waveform (26) constituting the other   of the system, the permanent magnet (22) being mounted adjacent to the discharge element (15) integrally with the cylinder (10) and the magnetostrictive waveguide (26) being provided along an axial bore (16b) of the discharge element being connected to the measurement electronics and the discharge element   (15) is of a non-magnetic material.   2) Running measurement system according to the   claim 1, characterized in that the permanent magnet   nent (22) is mounted inside the cylinder (10).   ) Stroke measuring system according to the   claim 1 or 2, characterized in that the magnet   (22) is mounted on the cylinder (10) of   adjacent to the end of the opposite cylinder (10) at the bottom of the cylinder.   ) Race measurement system according to one   claims 1 to 3, with an element of   piston-piston assembly, with it a damping piston housed movably in translation inside the cylinder and whose end face opposite the bottom of the cylinder is connected to the inner end of the cylinder; piston rod, the second component being integral with the piston, characterized in that the magnetostrictive waveguide (26) is provided along an axial bore (16b) of the piston rod (16) and the rod of piston (16) is of a non-magnetic material.   50) Travel measuring system according to the   claim 4, characterized in that the waveguide (26) is connected to the measurement electronics at the level of   the outer end of the piston rod (16).   ) Stroke measuring system according to the   claim 4 or 5, characterized in that the magnet   permanent magnet (22) is in the form of a permanent magnet   surrounding the piston rod (16).   ) Stroke measuring system according to the   6, characterized in that the permanent magnet   The annular ring (22) is a multipolar permanent magnet   to at least two partial magnets having a pole   radially on the inside and a magnet pole tick radially outward.   ) Stroke measuring system according to the   7, characterized in that the permanent magnet   The annular ring (22) has four partial magnets.   ) Race measurement system according to one   Claims 1 to 8, characterized in that at the   inner end of the waveguide (26), in the   (16b) of the discharge element (15), there is a damping path (28) for the pulses of   torsion flowing along the waveguide (26).