JPS60249002A - Moving distance sensor - Google Patents

Abstract

PURPOSE:To measure the moving distance of a movement detecting member or an object which is to be measured and is coupled thereto always with good accuracy and high resolving power by detecting the change of the restoring force of a spring by means of a lod cell and measuring the moving distance of said member or object. CONSTITUTION:The load cell 11 is constituted with a straight gage and detects the stress to be exerted thereto in the vertical direction. The detection signal is supplied via a lead wire 14 to a detecting circuit (not shown). The restoring force F=kx is generated by the contraction of a spring 12 (spring constant k) by (x) and is applied to the cell 11 if it is assumed here that a movement detecting rod 13 moves by (x) from the state shown in the figure. The cell 11 generates the signal proportional to the force exerted thereto and therefore the determination of (x) is made possible by said signal. The moving distance is thus measured always with good accuracy and high resolving power.

Description

DETAILED DESCRIPTION OF THE INVENTION (υ Industrial Application Field) The present invention relates to a moving distance sensor that detects the entire moving distance of a moving object.

(2) Conventional technology and its problems Figure 1 shows a conventional moving distance sensor.
It utilizes the principle of a so-called potentiometer, and a movement detection member (2) is in sliding contact with a resistor (IJ).A predetermined DC voltage is applied between both terminals (3) and (4) of the resistor (1). The movement distance (resistor (1) as shown by the arrow) is determined by the magnitude of the voltage generated between the movement detection member (2) and the output terminal (5) depending on the position of the movement detection member (2).
t-' in the vertical direction along the . However, if used many times, the sliding part (2a) of the movement detection member (2) (which is pressed against the resistor (11)) will wear out the resistor (1).In general, the resistor (1) will wear out. (The winding resistance is used as υ, but in such a case, in a certain winding part, the sliding part (2) of the movement detection member (2)
There may be no contact with a). This reduces measurement accuracy or resolution. Further, although the resolution is determined by the winding pitch, it cannot be made smaller due to its structure, and it further deteriorates due to wear.

(3) Object and Structure of the Invention The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a moving distance sensor that is always accurate and has high resolution. This purpose is achieved according to the invention by a load cell;
a spring coupled at one end to the load cell; and a movement detection member guided in the direction of expansion and contraction of the spring and coupled to the other end of the spring; This is achieved by a movement distance sensor, which detects a change in the restoring force of the spring using the load cell and measures the movement distance of the movement detection member or the object to be measured coupled thereto. Ru.

(4) Embodiments Hereinafter, moving distance sensors according to embodiments of the present invention will be described with reference to FIG.

In Fig. 2, a load cell aη is fixed to one part of the casing QQ, and a coil spring is attached to it.
are joined at one end. A movement detection rod (to) is fixed to the other end. The movement detection rod (to) is inserted into the hole (l) in the guide part formed on the bottom wall of the casing αQ.
oaf) and is guided so as to be movable in the extending direction of the coil spring (2), that is, in the direction shown by the arrow. The load cell east is constituted by a strain gauge as is well known, and is used to detect stress applied in the vertical direction. This detection signal is supplied to a detection circuit (not shown) via the signal line 141t.

Now, assume that the movement detection rod (2) has moved upward by X from the illustrated state. If the spring constant of the coil spring (2) is Qk, when this spring (2) contracts by X, F
A restoring force sound of = kx is generated, and this is added to all load cells Qv. Incidentally, it is assumed that the casing QQ is fixed to a stationary body even though it is not shown in the drawings. The load cell (b) generates a signal sound proportional to the applied force, so it can be charged using this signal.

A more detailed explanation is as follows.

Namely, a certain position! , to X, move the detection rod (2
) moves, then the restoring force F of the carp spring (b) is
k(XIx・) (where XO is the position of the movement detection rod (2) in the natural length of the coil spring (2)) is F, = k
(x, -x・). Accordingly, the lever difference Ft-F+
= k (, XI XI ), the moving distance can be measured by the load cell Oυ.

Since the restoring force of the coil spring 4 changes continuously and linearly with the magnitude of its expansion and contraction, the resolution of moving distance measurement can be further improved compared to the conventional method. 1+sensitivity can also be changed arbitrarily by selecting the spring constant ki. In the conventional example shown in Fig. 1, the movement detection member (2) slides @
(2m) becomes undetectable if it is even slightly separated from the resistor (1), but this does not occur in the present invention. Furthermore, in the conventional example, when the resistor (1) t or the sliding part (2a) of the movement detection member (2) wears out, the detection accuracy decreases, but in the present invention, the spring (2) and load cell (2) for detecting the movement amount decrease. 6)
Since no wear occurs on the tk, a constant precision tk can be guaranteed at all times. Note that sliding contact may occur between the movement detection rod (to) and the inner wall of the hole (10a) of the guide portion (to) of the casing QO, and wear may occur on these. Since the expansion and contraction of the spring (2) due to the moving distance in the vertical direction (2) is hardly affected, the measurement accuracy does not decrease completely.

In addition, although the case where the movement distance of the movement detection rod (2) itself is measured has been described above, by connecting or bringing an object into contact with this movement detection rod (2),
Of course, it is also possible to measure the distance traveled by the object.

The embodiments of the present invention have been described above, but of course the present invention is not limited thereto, and various modifications can be made based on the technical idea of the present invention.

For example, in the above embodiments, the moving distance in the vertical direction is measured, but of course it is also possible to measure the moving distance in the horizontal direction. In this case, the entire sensor t in Fig. 2 is
All you have to do is K in the direction of iFjR.

Further, in the above embodiments, a coil spring (2) is used as the spring, but the spring is not limited to this (for example, a rubber spring may be used. Also, a plurality of coil springs connected in series or in parallel may be used). .

(5) Effects of the invention As described above, according to the moving distance sensor of the present invention,
Travel distance can always be measured with high accuracy and high resolution.

[Brief explanation of drawings]

Figure 1 is a schematic side view showing a conventional example of a moving distance sensor;
and FIG. 2 are schematic cross-sectional views of a moving distance sensor according to an embodiment of the present invention. In the figure, 0・・・・・・・・・・・・・・・・・・Load cell (6)・・・・・・・・・・・・・・・・・・・・・
・Coil spring (to)・・・・・・・・・・・・・・・
...Movement detection rod agent Yasuo Iisaka Figure 2

Claims (1)

[Claims] A load cell: a spring coupled to the load cell at one end; and a movement detection member guided in the direction of expansion and contraction of the spring and coupled to the other end of the spring, the movement of the movement detection member in the direction of expansion and contraction of the spring. The moving distance sensor is characterized in that a change in the restoring force of the spring is detected by the load cell' to measure a moving distance of the movement detecting member or the object to be measured coupled thereto.