JPH06241261A - Detecting method of position of adjustment and stroke measuring device for executing said method - Google Patents

Abstract

PURPOSE: To minimize the tolerance of a parameter exerting influence on accuracy of a measuring result by generating a marking signal for at least one prescribed adjusting position of a first member by an auxiliary device. CONSTITUTION: A certain degree rough measurement for one or slight adjusting position is superimposed on very highly sensitive continuous precise measurement having a parameter based on time and a temperature to thereby obtain auxiliary information over an instantaneous value of one or a large number of parameters of an adjusting stroke to then correspondingly correct these parameters to minimize a measurement error. The measurement error is continuously minimized not only in one or a large number of prescribed adjusting positions but also over the whole measuring strokes. As a rule, a marking signal for one or a large number of adjusting positions is obtained by an opening/closing device for working mechanically or in a noncontact state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects the adjusted position of a first member relative to a second member of a device, in particular a shock absorber, which comprises two members which are movable relative to one another during an adjusting stroke. A method for producing a position signal by a measuring device which is continuously variable during an adjusting stroke depending on the adjusting position of a first member, and a stroke measuring device for carrying out this method. Regarding

[0002]

2. Description of the Prior Art Such a method is known, for example, from DE-A-4029633. In this known method or the known stroke measuring device for carrying out this method, it is designed to work according to the principle of the built-in stroke stroke sensor (Einfeder-weg sensor), in which case the measuring coil The inductance is influenced either by the magnetisable material or by a material with good conducting properties either directly on the basis of the adjusting position or indirectly according to the eddy current principle as follows. In other words, it is influenced in such a way that a sensor output signal is produced which is continuously variable over the adjustment process.

In such a known device, the sensor element is connected via a cable beam to the evaluation electronics provided in the sensor casing of the drive mechanism controller. In such a structure, the sensor elements cannot be balanced, which may result in large tolerances in relation to temperature changes, zero offset and sensitivity or amplification.

[0004]

Therefore, the object of the present invention is to reduce the tolerance of the parameters affecting the accuracy of the measurement results to a minimum, starting from the known method or the known stroke measuring device as described above. It is to provide a new method or stroke measuring device capable of performing the above.

[0005]

According to a method for detecting the adjusted position of a first member relative to a second member according to the invention for solving this problem, at least one of the first members is provided. A marking signal for a given adjustment position is produced by an auxiliary device. Also,
According to the inventive stroke measuring device for carrying out this method, an auxiliary device is provided which produces a marking signal for at least one predetermined adjustment position of the first member.

[0006]

According to the invention, the high sensitivity of the known continuous stroke measurement is fully utilized on the one hand, and on the other hand the marking signal for at least one predetermined adjustment position influences the measurement result. The advantage is that the parameters given can be modified during operation.

The basic idea of the method and the stroke measuring apparatus of the present invention is as follows. That is, a very sensitive continuous precise measurement with parameters based on time and temperature is overlaid with some coarse measurement for one or a few adjustment positions, which results in one or a few adjustment strokes. On passing through the position, one obtains ancillary information over the instantaneous value of one or several parameters and then modifies this parameter accordingly so that the measurement error is reduced to a minimum. . It is also intended to be continuously reduced to a minimum over all measuring strokes, not only at one or several predetermined adjusting positions. This measuring stroke may be the same as the adjusting stroke or may have one or several mechanically relevant ranges of this adjusting stroke.

In principle, the marking signals for one or several adjustment positions are obtained by mechanical or contactless working switchgear devices. The elements of the switchgear are mounted in predetermined positions on members which are movable relative to each other, in which case the position of the at least one adjusting position is actually Is also selected to be passed once after the shortest time. For example, as the adjustment position, a neutral position of members that are relatively movable with respect to each other is selected for a predetermined purpose of use.

According to another feature of the invention, the auxiliary device influences the inductance and / or the effective resistance of the measuring coil in the at least one predetermined adjusting position of the first member as follows: It is particularly advantageous to have a material which influences the pulsed marking signal produced by the measuring coil as the first member passes through this adjusting position. In this case, the material is preferably a magnet-operated, particularly highly magnetically permeable material, which has a direct effect on the inductance and / or the effective resistance of the measuring coil or on the measuring coil with an alternating current. To produce an eddy current,
It may be a material with good conductivity, which indirectly influences the inductance and / or the effective resistance of the measuring coil in relation to the frequency.

In addition, the inductance of the measuring probe and /
Alternatively, the material that affects the effective resistance is a material having good conductive characteristics, and an alternating current or an alternating voltage having a predetermined frequency is supplied to the measuring coil that produces an eddy current in the conductive material. Is particularly advantageous. In such an arrangement, which is capable of producing a continuously variable measuring signal over the adjusting stroke, the auxiliary device preferably supplies an alternating current for supplying the measuring coil with a second alternating current. The frequency of the eddy current having a source is significantly higher than the predetermined frequency for the first alternating current in order to obtain a deeper radial penetration depth in the material with good conductivity properties. At least one discontinuity corresponding to a predetermined adjustment position is provided in a material having a low and good electrical conductivity, the discontinuity being measured as the first member passes through; A pulsed marking signal is produced by the measuring coil on the basis of the lower frequency alternating current acting on the coil.

Advantageous configurations and variants of the method and the stroke-measuring layer according to the invention as defined in claims 1 and 2 are set forth in claims 3 and below.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows a single-tube shock absorber 2, but parts which are not essential to the invention have been omitted so that the parts important to the invention can be enlarged. There is. The shock absorber 2 mainly includes a cylinder 4, a shock absorbing piston 10, and a piston rod 12. The cylinder 4 has a peripheral wall 5, a first end face side 6 and a second end face side 8. The buffer piston 10 has a peripheral wall 5 inside the cylinder 4.
Is supported slidably in the axial direction along the inner peripheral surface 14. One end of the piston rod 12 is connected to the buffer piston 10, and the other end of the piston rod 12 penetrates the first end surface side 6 of the peripheral wall 5 of the cylinder 4 and projects from the cylinder 4. The seal member 15 provided on the first end face side 6
Seals the leak gap between this first end face 6 and the piston rod 12. The end of the piston rod 12 that projects axially beyond the cylinder 4 is connected to a first mass 16 (first member). The second end surface side 8 of the cylinder 4 is hingedly connected to the second mass body 18 (second member). The first mass body 16 is, for example, an automobile body, and the second mass body 18 is, for example, an axle. The inner chamber of the cylinder 4 is partitioned by the buffer piston 10 into a first working chamber 21 and a second working chamber 22. The first working chamber 21 is on the side of the cushioning piston 10 facing the first end surface side 6, and the second working chamber 22
Is on the side of the damping piston 10 facing the second end face side 6. In the drawing, the first working chamber 21 is above the cushioning piston 10 and the second working chamber 22 is below the cushioning piston 10. In order to compensate for the volume difference when the piston rod 12 moves in and out, for example, the second working chamber 2
2 is connected to the pressure accumulator 24. Two working chambers 21,
22 and the accumulator are at least partially filled with a pressure medium.

The two work chambers 21 and 22 have at least one
They are connected to each other by two flow connections 26. An electrically controlled magnet valve 28 is provided in the flow connection 26, for example. Through this magnet valve 28, the flow connection 26
It is possible to adjust the restriction of the pressure medium as it flows through. In addition to the flow connection 26, another flow connection 34 is provided for connecting the two working chambers 21, 22. In this further flow connection 34, for example a check valve 35
Can be provided. The flow connection 26 and the further flow connection 34 are arranged in the damping piston 10 in the exemplary embodiment shown. An annular groove 38 is provided on the outer peripheral surface 36 of the buffer piston 10. A measuring coil 40 is arranged in the annular groove 38. This measuring coil 40 comprises at least one coil 42 and preferably one core 44.
And have. The core 44 is made of, for example, a material having weak magnetism and high magnetic permeability, and sufficiently surrounds the coil 42. However, the coil 42 is
The side facing toward is not surrounded by the core 44 and is exposed. The coil 42 preferably comprises electrically conductive wire that is insulated and wound in multiple layers. Coil 42
Are likewise connected to the electronics 30 by lines 32. The core 44 significantly improves the operation of the measuring coil 40.

In addition to or instead of the measuring coil 40, another measuring coil 46 or measuring coil 4
8 may be provided. Another measuring coil 46 is arranged on the damping piston 10 on the side facing the first working chamber 21, and the other measuring coil 48 of the damping piston 10 facing the second working chamber 22. It is located on the end face side. The measuring coils 46, 48 likewise have a coil 42 and a core 44. For the stroke measuring system according to the invention, in principle only one coil 42 and thus one of the measuring coils 40, 46, 48 is sufficient, and if necessary these measuring coils 40 or 46 may be used. Or only one of the 48 is placed as conveniently as possible. The description of the measuring coil 40 also applies to the other measuring coils 46, 48.

The peripheral wall 5 of the cylinder 4 has an outer peripheral surface 54. A material layer 60 that affects the inductance of the coil 42 is disposed on the outer peripheral surface 54 of the cylinder 4.

Material layer 60 affecting inductance
For example, German Patent Application Publication No. 40296
As shown in FIG. 2 of U.S. Pat. No. 33, it has a notch 68 that is axially V-shaped, which allows a continuously varying position signal to be generated ( See FIG. 2). Further possibilities for the material or the shape of the material layer 60 for this purpose are described in the above-mentioned German Patent Application DE 4029633 A1.

The measuring coil 40 is an adjustment stroke which extends axially, ie in a direction parallel to the longitudinal axis of the shock absorber 2, and which is considerably shorter than the maximum permissible adjustment stroke. On the other hand, the material affecting the inductance extends over at least the entire length of the measuring stroke, in which case the material layer 60 has a greater circumferential angle than in the illustrated embodiment on the side of the second end face 8. At the first end face side 6
It is wrapped around the range. Therefore, depending on the adjustment position of the measuring coil 40 or the coil 42 with respect to the cylinder 4, the influence of the material layer 60 is large to some extent. In addition, the measurement coil 4 may be used in addition to the inductance.
The influence of the material layer 60 on the zero or the effective resistance of the coil 42 is a measure for the adjusting position of the measuring coil 40 along the adjusting stroke or in relation to the cylinder 4.

In the illustrated embodiment, the material affecting the inductance and / or the effective resistance is a good material, such as a material having a special structure or geometrical shape as described above, such as copper or aluminum. It is a material that is as non-magnetic as possible, having conductive properties. The peripheral wall 5 extends over at least the length of the adjusting stroke and is preferably made of a non-magnetically non-magnetic material, for example a suitable high-alloy steel. In this case, the inductance of the measuring coil 40 or the coil 42 is relatively large if the measuring coil 40 or the coil 42 exists within the range of the second end face side 8. This is because no eddy current is formed within the relatively wide notch 68 at this position. This eddy current can reduce the inductance of the measuring coil and / or its effective resistance based on the return effect acting on the measuring coil. On the other hand, the inductance of the measurement coil 40 or the coil 42 is relatively small in the range on the first end face side 6. This is because an eddy current is generated in the material layer 60 at substantially the entire circumference of the measuring coil at this point. The width of the notch 68 over the adjustment stroke is constantly changing, so that any detected adjustment position can be detected using the detected inductance of the measuring coil. Thus, the measuring coil 4
On the basis of supplying an alternating current having a predetermined frequency f1 to 0 or to the coil 42, it is possible to obtain a position signal which continuously changes over the adjusting stroke (see FIG. 2).

The structured material layer 60 is surrounded by a shield tube 80, as shown in FIG. 1, which is disposed within the shield tube 80 at predetermined intervals along the adjustment stroke. A plurality of notches 82 are provided. Now, when the measuring coil 40 is additionally supplied with an alternating current having a frequency f2 which is significantly lower than said frequency f1, a large radial outward penetration depth for the alternating magnetic field generated by the coil 40 is obtained. For the second frequency f2 as it passes through one of the cutouts 82 in the shield tube 82 made of a material having good electrical conductivity when the adjusting stroke is performed. The inductance of the measuring coil changes dramatically. A dramatic change in the coil inductance and / or the effective resistance of the coil is thus obtained, which change is superimposed on the continuous change in the parameters of the coil on the basis of the material layer 60. Therefore, the continuous “Fein signal” shown in FIG.
In addition to f, "Grob signal" shown in FIG.
g is obtained. This signal is transmitted by the electronics 30 at an adjustment position defined by the shield tube 80.
(Corresponding to the position of the notch 82 in FIG. 3) is adjusted so that a defined marking signal or marking pulse M is obtained (shown at the bottom of FIG. 3). This and corresponding results are shown in the schematic diagram of FIG. 4, where notches 82 'are made at appropriate points in the material layer 60.
Can also be obtained by providing. The shield tube can be omitted in some cases, especially if the markings or notches are provided directly in the magnetically actuated material.

As is apparent from the above description, in the method according to the invention, an adjustment step can be carried out and at the same time produce the fine signal shown in FIG. 2 and the coarse signal shown in FIG. In this case, the coarse signal is used to scale the fine signal, which changes continuously along the adjustment process. Particularly, in order to detect one marking signal M, according to the present invention, it is possible to detect and correct the shift of the zero point of the fine signal. Then, as soon as another marking signal M is detected during the course of the measuring process, the possibility of additionally adjusting the sensitivity of the sensor system in relation to the fine signal is obtained, and in FIG. There is a possibility to modify the slope of the straight line shown to some extent. As a result, based on the detection of the two marking signals, the sensitivity and the zero point shift for the fine signal can be detected and this can be corrected as required. This is preferably obtained by a microprocessor. This microprocessor calculates the necessary corrections from the measured values, stores them in the associated storage device and, if necessary, stores them as data (aufdatieren), so in some cases (except for a short start-up phase) A modified measurement is provided. This modified measurement value is very accurate, and thus a very accurate control signal for the magnet valve 28, for example, can be obtained.

The signal and voltage curve f or g shown in FIGS. 2 and 3 during the adjustment process is shown only as a qualitative curve and in this case the evaluation circuit. (Advantageously a microprocessor as described above)
Is well known to the expert and will not be described in detail here, but it is set up and programmed in such a way that a sequence is obtained for obtaining the signal and for evaluating this signal.

Further, the continuously variable position signal or the continuous measurement signal is a signal generated during the whole or a part of the measurement process. In this case, the digital signal causes a signal change different from the analog signal only at a predetermined small pitch, but the digital signal can be regarded as a continuous signal within the scope of the present invention.

[Brief description of drawings]

FIG. 1 is a longitudinal cross-sectional view taken along the axial direction of a single-tube shock absorber provided with a stroke measuring system according to an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between an adjustment process and a continuously variable position signal.

FIG. 3 is a diagram showing the relationship between an adjustment process and an auxiliary signal having an individual marking signal.

FIG. 4 is a schematic view showing a modified example of a structure portion for forming a marking signal.

[Explanation of reference numerals] 2 single tube type shock absorber, 4 cylinders, 5 peripheral wall,
6 1st end surface side, 8 2nd end surface side, 10 buffer piston, 12 piston rod, 14 inner peripheral surface,
15 seal member, 16 first mass body, 18 second mass body, 21 first working chamber, 22 second working chamber, 22 second working chamber, 24 pressure accumulator, 26 flow connection, 28 electrically controlled magnet valve, 30 electronics (Electronic control device), 32 lines, 34 flow connection, 35
Check valve, 36 outer peripheral surface, 38 annular groove, 40 measuring coil, 42 coil, 44 core, 54 outer peripheral surface, 60 material layer, 68 cutout, 80 shield tube, 82, 82 'cutout

Front page continuation (72) Inventor Horst Furman, Ludwigsburg, Germany Germany Ludwigsburg Strasse 8 (72) Inventor, Ralf Nortemaier Wernau Goethesutrasse 62 (72) Inventor, Wolfgang Welsch Heidelberg Schrader Strasse 16

Claims (11)

[Claims] 1. A method for detecting the adjusted position of a first member relative to a second member of a device, in particular a shock absorber, which comprises two members which are movable relative to one another during an adjusting stroke. A method for producing by the measuring device a position signal, which is continuously variable over the adjusting stroke in dependence on the adjusting position of the first member, by means of at least one predetermined adjusting position of the first member. A method for detecting an adjusted position, characterized in that the marking signal of (1) is generated by an auxiliary device. 2. A stroke measuring device for detecting the adjusted position of a first member with respect to a second member of a device, in particular a shock absorber, which comprises two members which are movable relative to one another during the adjusting stroke. A device of the type provided with a measuring device for producing a position signal which is continuously variable over the adjusting stroke in dependence on the adjusting position of the first member, at least of the first member A stroke measuring device for detecting an adjusting stroke, characterized in that an auxiliary device is provided which produces a marking signal for one predetermined adjusting position. 3. The first member is provided with a measuring coil, and the second member is provided with a material which influences the inductance of the measuring coil, which material is adjusted during the adjusting process. A position-analogically connected structure, wherein the auxiliary device is connected to the inductance and / or the effective resistance of the measuring coil by at least one of the first members.
Having a material which influences at one given adjustment position as follows: a pulsed marking signal is produced by the measuring coil as the first member passes through this adjustment position. The stroke measuring device according to claim 2. 4. A measuring device comprising two coils is provided, wherein one coil of the two coils is
The second member is configured as an exciting coil for supplying an electric alternating voltage and is connected to the first member, and the other coil of the two coils is configured as a measuring coil. And a variable position signal is generated on the basis of an electromagnet-type connection which is variable according to the distance between the two coils, the auxiliary device being arranged to /
Or, effectively, at least one predetermined adjustment position of the first member influences as follows: a pulsed marking signal is produced by the measuring coil as the first member passes through this adjustment position. 3. The stroke measuring device according to claim 2, comprising a material which influences so as to be produced. 5. The auxiliary device is configured to generate a marking signal for each of the at least two adjusting positions of the first member during the adjusting stroke.
The stroke measuring device according to any one of claims 2 to 4. 6. The material affecting the inductance and / or the effective resistance of the measuring probe is a material having good conductive properties, and a predetermined frequency is applied to a measuring coil which produces an eddy current in the conductive material. The auxiliary current is supplied to the measuring coil.
Has an alternating current source for supplying the alternating current of
The frequency of the eddy current is significantly lower than the predetermined frequency for the first alternating current in order to obtain a deeper radial penetration depth in the material with good conducting properties, At least one discontinuity corresponding to a predetermined adjustment position in the material with electrically conductive properties, which acts on the measuring coil as the first member passes through the discontinuity, the lower 4. The stroke measuring device according to claim 3, characterized in that a pulse-shaped marking signal is generated by the measuring coil on the basis of an alternating current of a frequency. 7. An evaluation device is provided, by means of which the position signal produced by the measuring device can be changed in order to increase the measuring accuracy on the basis of the marking signal produced. Item 7. The stroke measuring device according to any one of items 1 to 6. 8. The stroke measuring device according to claim 7, wherein the evaluation device is configured such that the deviation of the zero point of the position signal can be corrected by the evaluation device based on the marking signal. 9. The evaluation device determines, by the evaluation device, at least another parameter of the position signal in order to increase the measurement accuracy on the basis of the at least one other marking signal assigned to the further predetermined adjustment position. The stroke measuring device according to claim 8, wherein the stroke measuring device is configured to be variable. 10. The evaluation device comprises:
10. The stroke measuring device according to claim 9, wherein two predetermined position signals are assigned in response to the two marking signals, and the displacement of the zero point of the position signal and the sensitivity of the measuring device can be corrected. 11. A calculation and storage device is provided,
10. The calculation and storage device according to claim 7, wherein at least one correction value for the position signal or the measuring device can be calculated and stored on the basis of the at least one marking signal. The stroke measuring device according to item 1.