JPH0342501A - Range finder - Google Patents

Abstract

PURPOSE: To perform desired measurement even when the distance between two bodies is relatively long by disposing a short circuit coil at the other part of an equipment coupled with the other body. CONSTITUTION: One body moves with respect to the other body such that the intervals between a short circuit coil 60 and coils 50, 52, 54 are kept constant. More specifically, the insertion depth is varied but the interval 64 is kept constant. Alternatively, the coils 50, 52, 54 may be arranged on two bodies such that not the insertion depth but the interval between the surface of the coil 60 and the coil 50 and/or the coils 52, 54 are varied when one body slides on the other body. In this regard, first and/or second measuring voltage is varied and an electronic circuit 76 can detect the interval between two bodies mutually. Consequently, desired measurement can be carried out even when the distance between two bodies is relatively long.

Description

[Detailed description of the invention] l.

3. Industrial Field of Application The present invention provides a distance (
(interval) measuring device.

A part of the distance measuring device that already has one part of the body,
BACKGROUND OF THE INVENTION Distance measuring devices are known which are connected to another part of the distance measuring device with the other part of the body and can measure the adjusted position of one body with respect to the other body.

Known distance measuring devices function according to the so-called transformer method. A supply voltage is applied to the first coil. The measured voltage induced in the second coil can be measured, displayed on a display and evaluated by some means. The two coils are connected to one body. A soft core connected to the other body is slid between the two coils. 2
The degree of electromagnetic coupling between the two coils differs depending on the mutual positional relationship of the two members, and therefore the measured voltage of the second coil also differs. The measured voltage of the second coil is a measure of the adjusted position of one body relative to the other body.

In known distance measuring devices, the soft magnetic core of one body must be placed fairly closely to the coil of the other body. If the distance is relatively large, the coupling between the two coils is insufficient and it is not possible to obtain a meaningfully estimable measured voltage from the second coil.

Problems to be Solved by the Invention An object of the present invention is to provide a distance measuring device that can perform desired measurements even when the distance between two main bodies is relatively large.

Means for Solving the Problem The above problem is solved by configuring the other part of the distance measuring device, which is connected to the other main body, in each case to have a short-circuit coil.

If one part of the distance β window device is equipped with only two coils, a feed coil and a measuring coil, short structural dimensions are obtained.

If one part of the distance measuring device has one supply coil and two measuring coils, a measuring signal that can be evaluated particularly easily is obtained.

Embodiment The distance measuring device of the present invention is applied to a device in which the relative adjustment position of one body with respect to another body is to be detected. Depending on the adjusted position of one body relative to the other, a predetermined measurement signal is obtained. A predetermined measurement signal is assigned to each adjustment position. By evaluating this measurement signal, e.g.
It is detected whether one body is at a distance from the other body.

Although not limited thereto, in the embodiments of the present application for the distance measuring device of the invention, a shock attenuator is chosen as an example of application.

The embodiment shown in the drawing is a so-called two-tube shock attenuator (
shock absorber). The two-tube shock damper essentially comprises an inner cylinder 2, an outer cylinder 4, a damper piston 6, a piston rod 8 and a protective cap 10. The inner cylinder 2 has a first front face (end face) 12 and a second front face 14 . The outer cylinder 4 likewise has a first front face 16 and a second front face 18 . A first end surface 12 of the inner cylinder 2 is coupled to a first end surface 16 of the outer cylinder 4 via a tube member 19. A piston rod 8 projects on the first front surface 4 of the external cylinder 4 . The piston rod 8 is connected to both first front surfaces 1 of the two cylinders 2.4.
2.16 into the internal cylinder 2. The piston rod is connected with the damper piston 6 by its end lying in the inner cylinder 2. With its other end projecting from the outer cylinder 4, the piston rod 8
is connected to a mass body 20. The second end face 18 of the outer cylinder 4 is connected to the second mass 22 . First mass body 2
0 is, for example, a vehicle structure, and the second mass body 22 is, for example, a vehicle axle. The damper piston 6 is able to slide along the inner circumferential wall surface 24 of the inner cylinder 2 in the axial direction. The interior space of the inner cylinder 2 is divided by the damper piston 6 into a first working chamber 26 and a second working chamber 28 .

In the drawing, the first working chamber 26 is located above the damper piston 6,
A second working chamber 28 is present on the lower side. external cylinder 4
surrounds the inner cylinder 2 at a distance, so that an equilibrium chamber 30 is formed between the outer cylinder 4 and the inner cylinder 2.
is formed. The two working chambers 26, 28 and the balancing chamber 30 are at least partially filled with pressure medium.

The two working chambers 26 , 28 are interconnected via a first valve 32 and a second valve 34 provided on the damper piston 6 . A third valve 3 is provided on the second front surface 14 of the internal cylinder 2.
6 and a fourth valve 38 are provided.

When the piston rod 8 enters the inner cylinder 2 , pressure medium flows from the second working chamber 28 through the first valve 32 into the first working chamber 26 . At that time, in the second working chamber 28, the first
More pressure medium is forced out than can enter the working chamber 26.

Therefore, when the piston rod 8 enters, a part of the pressure medium also passes from the second working chamber 28 through the fourth valve 38 to the equilibrium chamber 30.
flows into. When the piston rod 8 enters the inner cylinder 2, the second valve 34 and the third valve 36 are closed. The pressure medium is transferred from the second working chamber 28 to the first working chamber 26 through the first valve 3
2 and flows in without being restricted in any way. The throttling of the pressure medium, which determines the damping of the shock damper, takes place when the piston rod 8 enters the inner cylinder 2 by throttling the pressure medium by means of the fourth valve 38 .

When the piston rod leaves the inner cylinder 2, pressure medium flows from the first working chamber 26 through the second valve 34 into the second working chamber. However, the first working chamber 2
It is possible for more pressure medium to flow in than to be forced out from 6. From the balance chamber 30, the pressure medium thus flows into the second working chamber 30 via the third valve 36. The pressure medium flows through the third valve 36 almost unrestricted. The throttling of the pressure medium defining the damper when the piston rod 8 exits is effected by the second valve 34 . When the piston rod 8 emerges from the internal cylinder 2, the first valve 32 and the fourth valve 38 are closed.

Internal 7 cylinder 2 and external cylinder 4 in tube member 19
A seal 42 provided between the first front faces 12 and 16 prevents leakage from the first working chamber 26 to the outside along the guide gap 44 between the piston rod 8 and the tube member 19.

The hole portion 46 communicates and connects a portion of the guide gap between the packing 42 and the first working chamber 26 and the equilibrium chamber 30 .

The hole 46 is used to protect the seal 42 against excessively high pressure caused by the bow flow when the piston rod 8 exits.

A protective cap IO is connected together with the piston 8 to the end of the piston rod 8 which is connected to the first mass 20 . A protective cap IO at least partially surrounds the outer cylinder 4.

The cylindrical portion 48 of the protective cap 10 includes a power supply coil 5.
0, a first measuring coil 52 and a second measuring coil 54 are provided. The cylindrical part of the protective cap IO is preferably made of plastic. The feeding coil 50 and the two measuring coils 52,54 are connected to the cylindrical part 48 of the protective cap lO.
It is infused into. A short circuit coil is arranged on the outer circumferential wall surface 56 of the outer cylinder 4. The short-circuit coil is at least partially surrounded by a plastic casing 62 to protect it from environmental influences.

The cylindrical part 48 of the protective cap 10 is connected to the piston rod 8 only on one side, and due to the harsh environmental influences to which part of the shock damper is exposed, a short-circuited coil 60 with the cylindrical part 48 and the casing 62 A relatively large spacing 64 must be provided between the two.

The feeding coil 50 is positioned and arranged in the cylindrical portion 48 of the protective cap 10 as follows. That is, the feeding coil 50 is positioned and arranged to surround the short-circuiting coil 60 no matter where the piston rod 8 is located. The feeding coil 50 is located between the two measuring coils 52,54. The first measuring coil 52 is connected to the feeding coil 50 in the axial direction.
A second measuring coil 54 is connected to the feeding coil 50 on the side opposite to the feeding coil 50 in the axial direction. The first measuring coil 52 is arranged on the side of the power supply coil 50 facing the first mass body 20 . The second measuring coil 54 is the feeding coil 50 facing the second mass body 22.
placed on the side of The length of the first measuring coil 52 is preferably as follows. That is, the length is such that even when the piston rod 8 is completely inserted, the first measurement coil 52 protrudes slightly more axially toward the first mass body 20 than the shorting coil 60. The second measuring coil 44 has the following length. That is, the length is such that even when the piston rod is fully extended, the second measuring coil protrudes a little further toward the second mass body 22 in the axial direction than the shorting coil 60.

The short-circuit coil 60 is preferably wound mainly in -layers;
It consists of a conductive material 66 surrounded by an insulating material. Depending on the case, it may be wound in multiple layers. Conductive material 66
is an insulated copper wire, for example. The conductive material 66 is the short circuit coil 6
0 on the front side facing the first mass 20 and terminating with a first end 68 on the front side facing the first mass 22 of the shorting coil 60 .
c2 end 70 terminates. The first conductive material 66
End 68 is connected to second end 70 of conductive material 66 by conductive member 72 . The conductive member 72 is, for example, a copper wire wrapped in plastic.

Power supply coil 50. The first measuring coil 52 and the second measuring coil 54 are connected to an electronic circuit 76 via a cable 74 . The cable 74 consists of a plurality of electrical lines, two lines each leading to the feeding coil 50 and the two measuring coils 52,54. The electronic circuit 76 is connected to the cable 74
A supply voltage is supplied to the power supply coil 50 via the power supply coil 50 . The first measurement voltage induced in the first measurement coil 52 is
can be supplied to the electronic circuit 76 via. A second measurement voltage induced in the second measurement coil 54 can likewise be supplied via a cable 74 to an electronic circuit 76 .

Due to the supply voltage developed in the feeding coil 50, the supply current flows through the feeding coil 50. The supply voltage is an alternating voltage and preferably has a sinusoidal profile. Power feeding coil 50
The supply current within acts on the intersecting magnetic fields. This magnetic field induces a voltage in the shorting coil 60. However, this voltage is shorted. The short-circuit current flowing as a result is the short-circuit coil 6
0 through the entire winding of conductive material 66, again forming a magnetic field over the entire length of the shorted coil. Short circuit coil 60
The current flowing through the electrically conductive material 66 induces a first measuring voltage in the first measuring coil 52 depending on the penetration distance of the shorting coil 60 into the first measuring coil 52 . However, the current flowing through the conductive material 66 also induces a second measurement voltage in the second measurement coil 54 depending on the penetration distance of the shorting coil 60 into the second measurement coil 54 .

The first measured voltage and the second measured voltage are measures for the relative adjustment position of the shorting coil 60 of the supply coil 50 and of the two measuring coils 52 , 54 with respect to the protective cap 10 .

The first and second measured voltages can be evaluated in a known manner by an electronic circuit 76 and displayed and/or displayed if desired.
or for example to be supplied as an actual value to a control circuit.

Particularly advantageously, the short-circuiting coil 60 can be provided anywhere, and there is no need to lead out cables or other elements from the short-circuiting coil 60. The short-circuit coil 60 can be completely cast in plastic, so that it is optimally protected against environmental influences.

The configuration of the feeding coil 50, the two measuring coils 52, 54 and the shorting coil 60 is exemplary. Of course, it is also possible to arrange the short-circuiting coil 60 on the protective cap lO and the supply coil together with the two measuring coils 52, 54 on the outer circumferential wall surface 56 of the outer cylinder 4. Preferably, however, the coils 50, 52.54 are connected to the electrode 76 and the coil 5052.5.
4 can be easily and problem-free connected via cable 76. - A particular advantage is that there is no need to connect a cable to the short-circuit coil 60. As a result, short-circuiting coils can be placed without problems even in components where cable connection is impossible or problematic.

Feeding coil 50, first measuring coil 52, second coil 54
, cable 74, electronic circuit 768 and shorting coil 60 together form a distance measuring device. First mass body 20, piston rod 8, damper piston 6, coil 50.52.5
The protective caps IO with 4 are relatively fixed to each other and can therefore be considered as one body. The inner cylinder 2, the outer cylinder 4, the second mass and the short-circuit coil 60 are likewise not movable relative to each other and are therefore considered to be two bodies. Both bodies are part of the device. Both bodies of the device are slidable relative to each other. The distance measuring device according to the invention makes it possible to detect the adjustment position of one body relative to the other body.

In the illustrated embodiment, one body moves relative to the other body as follows. That is, the spacing of the shorting coil 60 relative to the coils 50, 52, 54 is moved to remain substantially the same. In other words, although the insertion depth varies, the spacing is 6
4 stays the same. However, when one body is slid relative to the other body, the spacing of the surface of the short-circuiting coil 60 with respect to the feeding coil 50 and/or with respect to the first and second measuring coils 52, 54, rather than the insertion depth, changes. Additionally, it is also possible to arrange the coils 50,5254.60 in two bodies. In this case, the first and/or second measuring voltage changes and the electronic circuit 76 is able to detect the distance between the two bodies relative to each other.

Measuring coil 52 instead of two measuring coils 52,54
．． Only one of 54 can be used. If only one measuring coil 52 is used, the cylindrical part of the protective cap 10 can be constructed shorter than when two measuring coils 52,54 are used. Either the feeding coil 50 or the measuring coil 52 or 54 is always short-circuited.
It is proposed to surround 0.

If there are two measuring coils 52,54, the difference between the two measuring voltages can advantageously be used for further evaluation.

The supply coil 50 and the two measuring coils 52, 54 can be connected in common to an electronic circuit 76 in a known manner. For example, "'Handbuch furelektr
isches Messen mechanics
her Groeβen1967 Hayabusa, Christop
h Rohrbach, p. 190. There, a soft magnetic iron core is used instead of the short circuit coil 60 of the present invention. The author cites low efficiency as a drawback of his distance measuring device, shown on page 190. R
If the soft magnetic iron core of the distance measuring device shown by Ohrbach is replaced by a short circuit coil 60 as in the present invention,
The working efficiency and linearity area are clearly increased. Thereby, advantageously, the short-circuit coil 60 and the other coils 50.52.5
4 can be selected to be relatively large, and a sufficiently large and easily estimable measuring voltage is obtained from the measuring coil 52,54.

A great advantage of the distance measuring device according to the invention is that the spacing 64 can be chosen larger than in known distance measuring devices, so that even though the distances are sufficiently large, the signal amplitude can still be evaluated well. is obtained. The spacing 64 can obviously be selected to be greater than 6 mm.

The fact that the spacing 64 can be sufficiently selected greatly simplifies the construction and, in particular, the manufacture and selection of the materials used in the case of the shock damper. Plus protective cap 10
Even if the cylinders 2 and 4 slide only slightly, the relatively large spacing 64 hardly falsifies the measurement result.

If the spacing 64 is relatively large, the measuring coil 52.54
The measuring voltage induced in the damper piston is approximately linear over the entire measuring distance (which corresponds to the stroke of the damper piston).

If the frequency of the supply voltage of the feeding coil 50 is suitable, temperature has no or very little influence on the measurement results. The appropriate frequency depends on the configuration and type of coils 50, 52, 54, 60.

With the distance measuring device according to the invention, distances can be measured contactlessly and quickly with slight temperature dependence. Power supply and evaluation can be done using ICs available on the market.

The distance measuring device of the present invention can be applied to any device in which two bodies are slid facing each other and their adjusted positions are to be detected relative to each other. The distance measuring device of the invention is not limited to shock attenuator applications only. In particular, the distance measuring device can be applied to each type of telescoping fork, for example a telescoping 7-orc with an air spring element.

Effects of the Invention The invention provides a distance measuring device which is capable of performing satisfactory measurements even when the distance distance between two bodies is relatively large.

4

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of a distance measuring device according to the present invention. 2...Inner cylinder, 4...Outer cylinder, 6...
・Attenuator piston, 8...Piston rod, lO...
・Protection camp

Claims (1)

[Claims] 1. A distance measuring device that has two members that are slidable relative to each other and that detects the adjusted position of one member with respect to the other member, and that includes a plurality of coils. A distance measuring device in which the distance measuring device part is coupled to one of the two members, characterized in that the other part of the distance measuring device, each coupled to the other member, has a short-circuit coil (60). Distance measuring device. 2. The distance measuring device according to claim 1, wherein one part of the distance measuring device includes a feeding coil (50) and one measuring coil (52, 54). 3. Distance measuring device according to claim 1, characterized in that one part of the distance measuring device has a feeding coil (50) and two measuring coils (52, 54).