JPH0455720A - Displacement detector - Google Patents

Abstract

PURPOSE:To obtain the stable output from a magnetic sensor by alternately forming N poles and S poles in the direction of an axial line on the respective surfaces of both side surface parts of a channel-shaped body. CONSTITUTION:Magnet plates 24 and 25 on which N poles and S poles are alternately magnetized are stuck in the direction of axial line on inner surface sides of both side surface parts 22 and 23 of a channel-shaped body 20. When a saturable coil 27 is moved from an original point O in the direction X, the output of a detecting circuit which is applied on the coil 27 is proportional to the moving amount. When the coil 27 is moved in the direction Y by vibration and the like, the amount of the magnetic flux which is interlinked with the coil 27 is not changed when the coil 27 is positioned in a groove part 26. This is because the direction Y in the groove part 26 has the approximately parallel magnetic field. Therefore, the output voltage of the detecting circuit is not changed. When the coil 27 is moved in the direction Z, the approximately constant strength of the magnetic field is obtained since both magnetic plates 24 and 25 are present. Therefore, the output of the detecting circuit which is applied on the coil 27 is hardly changed. Thus, the stable output is obtained from the coil 27 even under the vibrating environment.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a displacement detection device suitable for application to, for example, a mechanical device or an inspection device under a vibration environment.

[Summary of the Invention] The present invention provides a displacement detection device suitable for application to, for example, a mechanical device or an inspection device under a vibration environment. a channel-like body having By forming these alternately, for example, even if the magnetic sensor fluctuates in a direction perpendicular to the axial direction under a vibration environment, a stable detection output can be obtained from the magnetic sensor.

[Prior Art] Conventionally, a potentiometer, which is a variable resistor, has been used as a displacement detection device, for example.

Since the resistor and movable contact of this potentiometer slide, the life cycle of this potentiometer is relatively short, and poor contact is likely to occur in a vibrating environment. There was a problem in adopting this method because there is a risk of sparks being generated due to sliding or the like since there is a current flowing through the wire.

In order to solve this difficulty, a non-contact type, for example, a magnetic displacement detection device has been proposed. FIG. 12 shows an example of this type of magnetic displacement detection device (hereinafter referred to as displacement detection device). This displacement detection device has a magnet (
2) (3) is arranged, and a detection head (5) having a magnetic sensor (4) is arranged above the magnet (2> (3) with a clearance d).

In use, by relatively displacing the detection head (5) in the direction of the arrow X, an output voltage proportional to the displacement can be obtained within a fixed section from the origin O in the X direction.

[Problems to be Solved by the Invention] However, in this displacement detection device, when the detection head (5) changes relatively in the Z direction in the figure, that is, in a vibration environment etc. magnet(
2> When the clearance d with (3) changes,
As shown in Fig. 13, even a slight change in the clearance d causes an extremely large change in the output voltage. The drawback was that it could not be adopted.

In this case, in order to keep the clearance d constant, for example, as in the displacement detection device shown in FIG. 14, a ribbon-shaped magnetized scale (7) is placed on an iron base (6).
(Magnetization pitch is, for example, 4 mm).A stainless steel cover (8) with a thickness of 1 mm is tightly fixed thereon.
It is also possible to obtain a sine wave output and a cosine wave output by relatively displacing the detection head (11) having the magnetic sensors (9) and (10) upward in the direction of the arrow X.

However, due to the contact type configuration, the life cycle is relatively short, and when used in a vibrating environment, clearance fluctuations occur, resulting in sudden fluctuations in the output voltage. , detection head (11)
There was a limitation in that the use was limited to precision mechanical devices that had a structure that had a member that held the parts.

The present invention has been made in view of this point, and it is possible to obtain a stable detection output from the magnetic sensor even under a vibration environment, in other words, even if the clearance between the magnetic sensor and the magnet changes. The present invention also aims to provide a non-contact displacement detection device.

[Means for Solving the Problems] The displacement detection device of the present invention has, for example, as shown in FIG.
A channel-shaped body 20) having a bottom part (24), both side parts (22) (23), and a groove part (26) formed by the bottom part (24) and both side parts (22) (23>); a magnetic sensor (27) disposed in groove #B (26>) of the channel-shaped body (20); N pole and S pole in the axis X direction of the channel-like body (20)
The poles are alternately formed.

[Function] According to the present invention configured as described above, the direction perpendicular to the axis X of the channel-like body (2Q) (Y-Z plane ) is approximately constant, the magnetic sensor (27) disposed within the groove (26) of the channel-shaped body (20) is moved in the direction perpendicular to the axis X due to vibration etc.
In other words, the magnetic sensor (27) outputs an output even if it moves toward both side surfaces (22) and (23), or moves toward the bottom (24) or the opposite side of the bottom (24). An effect is obtained in which the amplitude of the output signal is substantially constant, that is, does not fluctuate. Therefore, even under a vibration environment, stable output can be obtained from the magnetic sensor (27).

[Embodiment] An embodiment of the displacement detection device of the present invention will be described below with reference to the drawings. In Fig. 1, (20) is a channel-shaped body made of iron (thickness 1 mm) made by bending, etc.
It has side parts (22), (23) and a bottom part (24). The size of this channel-like body (20) is the depth yi
=tsmm, length xl=2Qmm.

The inner width Z1 is 17 mm. In addition, this channel-like body (2
Both side surfaces of (22) and (23) have a thickness of 03 gmm with N and S poles alternately magnetized, respectively.
The magnet plates (24) and (25) are arranged so that the N and S poles face each other and in the axial direction of the channel-like body (20) (X in the figure).
direction).

Furthermore, the internal space groove a'B (2) of the channel-like body (20)
A saturable coil <27) as a magnetic sensor is arranged at 6). This saturable coil (27) has saturable coils (27a) and (27b) as shown in FIG.
Cut a rectangular shape in the center (1 x 3rnm)
A rectangular core (28) having a winding (29) (30
) is arranged so that the plane part of the core (28) coincides with the Y-2 plane in FIG.
8) are arranged so that the vertical line portions in the figure coincide with the Z direction. Note that the saturable coil (27) is actually attached to a head holder (27) that is movable in the X direction, as shown in FIG.
31) is configured in a fixed manner.

The output terminals of the saturable coils (27a) and (27b) are the fourth
It is connected to the detection circuit (32) shown in the figure. This detection circuit (32) is a pulsed voltage oscillator (3) of approximately 50kHz.
4), and is configured to be supplied with the output voltage of the saturable coil (27). In Figure 4, (35) is a transformer, (36) (36) is a series resistor, (37) (
37) is a diode, (38) (38) is an output resistor,
(39) (39) (40) is a capacitor, which generates an analog voltage output at the output terminals (33a) and (33b). To explain in detail the process of generating analog voltage output, the saturable coil (27a), (
The cores (27b) are brought into a substantially magnetically saturated state in opposite directions by a pulsed current supplied from the transformer (35) based on the pulsed voltage oscillator (34), and the cores (27b)
When a DC magnetic field is applied to 8), the inductance of one saturable coil (for example, the saturable coil (27a)) increases, and the inductance of the other saturable coil (therefore, the saturable coil (27b)) decreases. It changes like this. The diode (
The pulsed voltage supplied to the anode side of 37), (37) changes, and the output resistance (38), (38) changes accordingly.
The rectified voltage generated will also change. Since changes in these rectified voltages occur in opposite directions, the difference between these two rectified voltages becomes the output of the detection circuit (32). In addition, the detection circuit (3
2) is designed to generate a voltage of ±5 volts when a magnetic field of ±50 Gauss acts on the saturable coil (27). Further, the output of the detection circuit (32) is not limited to analog output, but may be digital output.

In FIG. 1 again, the -Y direction in the figure is the normal direction of the bottom part (24), and the X direction is the direction of the bottom part (24) and the side part (24).
This is the so-called axial direction parallel to each of the planes 2) and (23). That is, the xSy and z axes constitute an orthogonal three-dimensional coordinate system, and in the figure, the origin O is selected to be the center point of the depth yl, the length xl, and the inner width z1, respectively.

Therefore, the X-axis coincides with the axis of the channel-like body (20).

Next, the operation of the above embodiment will be explained.

First, when the saturable coil (27) moves from the origin ○ in the X direction, the detection circuit (
32) is an output proportional to the amount of movement, that is, the amount of displacement (see characteristic a1 in FIG. 5). This is similar to the characteristic curve shown in FIG. 13 described above. Furthermore, the fifth
On the right side of the figure, one scale on the horizontal axis indicates 0.5 mm in the X direction,
One scale on the vertical axis indicates 1 volt. In addition, in the same figure, the characteristics a2 to a6 are obtained by changing the sizes of the magnets (24) and (25) as shown in FIG.
=3.6.5.8.10. This is the output characteristic when attached to the inner surface of the side surface (22) (23) of the channel-shaped body (20) with ) and the magnet plate (25b') becomes wider, the slope becomes gentler.

Next, referring to FIG. 1 again, assume that the saturable coil (27) moves in the Y direction due to vibration or the like. In this case, since the Y direction inside the groove (26) has a substantially uniform magnetic field, when the saturable coil (27) is located in the rectangular parallelepiped groove (26) formed by the channel-shaped body (24), Since the amount of magnetic flux linked to the saturable coil (27) does not change, the output voltage of the detection circuit (32) does not change (7th
(see figure). In FIG. 7, ΔY is a parameter and indicates the amount of movement in the Y direction from the origin ◯ (unit: mm). In addition,
In FIG. 7, one scale on the horizontal axis indicates 1 mm in the X direction,
One scale on the vertical axis indicates 1 volt. The figure also shows the characteristic a4 shown in Fig. 5 (in Fig. 6, p = 3 m
This shows the characteristics of the displacement detection device m).

Next, referring again to FIG. 1, the saturable coil (27) is
A case where the direction changes will be explained. In this case, if it is assumed that only the upper magnet plate (24) in the figure exists, the strength of the magnetic field in the groove (26) will be as shown in characteristic b1, as shown in FIG. It has a characteristic that it is maximum at the surface of the magnet plate (24) and gradually weakens as it moves away from the magnet plate (24) in the Z direction. Similarly, the magnetic plate (
If only 25) exists, the characteristic will be as shown in characteristic b2. Therefore, when both magnet plates (24) and (25) are present, their characteristics b1 and b2 become characteristic b3, which results in a substantially constant magnetic field strength in the Z direction. The output of the detection circuit (32) applied to the saturable coil (27) hardly changes as the saturable coil (27) moves in the Z direction (see FIG. 9). In FIG. 9, ΔZ is a parameter and indicates the amount of movement in the Z direction from the origin 0 (unit: mm). In FIG. 9, one scale on the horizontal axis indicates 1 mm in the X direction, and one scale on the vertical axis indicates 1 volt. Also, the same figure also shows the fifth
This shows the characteristics of the displacement detection device having the characteristic a4 shown in the figure.

In this case, according to the embodiment described above, the channel-like body (20
) The strength of the magnetic field in the direction perpendicular to the axis X of the channel-like body (20) (any direction in the Y-Z plane) within the groove (26) is approximately constant. , even if the saturable coil (27) serving as a magnetic sensor disposed in the groove (26) of the channel-shaped body (20) moves toward both side surfaces (22) and (25) (Z direction) due to vibration etc. The amplitude of the output signal output from this saturable coil (27) remains approximately constant even if it fluctuates toward the bottom surface ais (24) side (Y direction) or the side opposite to the bottom surface portion (24) side (-Y direction). Therefore, there is an advantage that it is possible to construct a displacement detection device that can obtain a stable output from the saturable coil (27) even under a vibration environment. .

FIG. 10 shows the configuration of another embodiment of the displacement detection device of the present invention, and FIG. 11 is a circuit diagram related to this embodiment.

In FIG. 10, the channel-like body (40) has a bottom surface I (
40a), side portions (40b), (40c), and a groove portion (40d) formed by these, and is formed by bending a 1 mm thick iron plate. The inner width z2 of this channel-like body (40) is z2=12
mm, and the depth y2 is 5'2=13 mm. Two rubber magnets (40a) and (40b) each having a magnetic scale with a pitch of 4 mm are placed on the inner side surfaces (40a) and (40b).
41a) and (41b) are bonded so that the north pole and the south pole face each other. It has a so-called magnetic scale configuration. Stainless steel plates (42a) (42b) are attached to the surfaces of the rubber magnets (41a) and (41b) for protection. Then, the groove l (
40 (1) has a detection head (with a thickness of about 7 mm in two directions).
43) is placed. Therefore, the detection head (43) and the stainless steel plates (42a) (42b) in the Z direction
The clearance between the surfaces is 2.
5 mm, but even if the detection head (43) varied during this period, there was almost no change in its detection output.

Note that inside this detection head (43) there is a saturable coil (27) (10th coil) as a magnetic sensor shown in FIG.
(not shown in the figure) are fixed. The interval between the saturable coils (27), (27) is 3 mm in the X direction, and the plane portions of both cores (28) (28) coincide with the YZ plane. In this case, as shown in FIG. 11, the circuit connected to the detection head (43) includes two detection circuits (32) as described above, and a well-known interpolation circuit (
44) and a counter (45).

The interpolation circuit (44) receives sine wave and cosine wave voltages from the detection circuit (32) (32) when the detection head (43) moves in the X direction, and generates a plurality of pulses, for example, 40 pulses per cycle. Occur. This pulse output is output by a counter (
45) to obtain an output signal representing the position.

Note that the present invention is not limited to the above-described embodiments, and it goes without saying that various configurations can be adopted without departing from the gist of the present invention.

[Effects of the Invention] According to the displacement detection device of the present invention, the strength of the magnetic field in the direction perpendicular to the axis of the channel-like body within the groove formed by the channel-like body is approximately constant. Even if the magnetic sensor placed in the groove of the shaped body moves in a direction perpendicular to the axis due to vibration, etc., in other words, to both side surfaces, or to the bottom side or the opposite side from the bottom side, etc. , it is possible to obtain an effect that the amplitude of the output signal outputted from this magnetic sensor is a substantially constant amplitude, that is, it does not fluctuate. Therefore, there is also an advantage that a stable output can be obtained from the magnetic sensor even under a vibration environment.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the configuration of an embodiment of the displacement detection device according to the present invention, FIG. 2 is a front view showing the detailed configuration of the saturable coil shown in FIG. 1, and FIG. 4 is a detection circuit diagram, FIG. 5 is a characteristic diagram when the magnetic sensor is moved in the X direction, FIG. 6 is a perspective view showing a modification of the magnet arrangement, and FIG. 7 is a diagram of the magnetic sensor. A characteristic diagram when the magnetic sensor is moved in the Y direction, FIG. 8 is a characteristic diagram explaining the strength of the magnetic field in two directions, FIG. 9 is a characteristic diagram when the magnetic sensor is moved in the Z direction, and FIG. 10 is a characteristic diagram of the present invention. FIG. 11 is a circuit diagram applied to the displacement detection device shown in FIG. 10, and FIG. 12 is a side view of the displacement detection device according to the prior art. , FIG. 13 is a characteristic diagram for explaining the operation of the displacement detection device shown in FIG. 12, and FIG. 14 is a perspective view showing the configuration of another conventional displacement detection device. (4) is a namannel shape, and the enemy is a flexible coil. Agent Hide Mori Matsukuma Figure 2 Figure 4rllI Rakuten scale l2 #A] Output circuit Figure 11 Figure 14

Claims (1)

[Scope of Claims] A channel-shaped body having a bottom surface, both side surfaces, and a groove formed by the bottom surface and both side surfaces, and a magnetic sensor disposed in the groove of the channel-shaped body, 1. A displacement detection device characterized in that N and S poles are alternately formed on each side of the channel-shaped body in the axial direction of the channel-shaped body.