JPH01302101A - Position detecting device - Google Patents

Abstract

PURPOSE:To improve accuracy and resolution and simplify a structure by a method wherein a plurality of magnetic materials are arranged in an axial direction of a movable rod in accordance with a magnet and change in inductance of coils wound around the respective magnetic materials is detected as a digital signal. CONSTITUTION:While voltage of high level is generated in resistors R1 to R8 connected in series with magnetic sensors M1 to M8 consisting of a coil 11 wound around a magnetic material 10 which corresponds to a protruding portion 4 of a rod 2a, voltage of low level is generated in resistors R9 to R16 connected in series with magnetic sensors M9 to M16 which correspond to a groove 3 of the rod 2a. A digital signal of ON-OFF is specified with the intermediate voltage of this high-level voltage and the low-level voltage as a threshold level. This digital signal is taken out as binary output by a latch circuit 15 and a code conversion circuit 17.

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention [Field of Industrial Application] The present invention relates to a device for detecting a movable rod device.

[Problems to be solved by conventional techniques and inventions 1 Conventionally,
One way to directly measure the distance traveled by a rod is to create multiple grooves in the rod in parallel in the axial direction and count the pulses of these grooves using a photoelectric or electromagnetic method. It has been difficult to obtain high accuracy and high resolution (for example, a rod movement distance of 0.1 mm) due to restrictions on the groove width that can be achieved.

The excitation coil and the detection coil are set as one set, and four sets are arranged around the outer circumference of the rod, and two sets of each are set i [such as a resolver that detects position changes due to eddy current by adding a sinusoidal waveform and a cosine waveform. There are ways to do this, but the problem is that the circuit is complex and adjustment is difficult.

Other methods have used ultrasonic sensors, differential transformers, potentiometers, etc., but it has been difficult to incorporate them into the rod.

An object of the present invention is to cover the structure in a cylinder in a device that directly detects the position using the rod itself as a scale.

Structure of the Invention [Means for Solving the Problems] The position detection device according to the present invention has been realized for this purpose, and includes a movable rod in which a plurality of grooves are arranged in parallel in the axial direction, and a magnetic field on the movement locus of the movable rod. A magnet to act on, a plurality of magnetic bodies arranged in parallel in the axial direction of the movable rod in correspondence with the magnet,
Detecting means for detecting a change in the magnetic field due to the movement of the movable rod as a change in permeability of the magnetic body is shown on the right.

Further, the position detection device according to the present invention detects changes in the inductance of a coil wound around each magnetic body as a digital signal.

[Function] In the position detection device according to the present invention, when the movable rod moves, the magnetic field of the magnet changes, and due to the change in the magnetic field, the permeability of each magnetic body also changes, and this change can be detected. can. For example, if a coil is wound around each magnetic material, the inductance of each coil will change due to a change in the magnetic permeability of each magnetic material, and this change can be detected as a digital signal.

[Example] An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, a position detecting device 1 according to this embodiment is incorporated into the outer periphery of a screw rod 2a (movable rod) of an air cylinder 2. As shown in FIG. As shown in FIG. 2, a plurality of grooves 3 and convex portions 4 between them are formed on the outer periphery of the screws 1 to 2a in correspondence with the position detection device 1. They are arranged alternately in parallel in the line direction. ) 83 and the axial length [4] of the convex portion 4 are close to each other, and the depth [] of the groove 3 and the height H of the convex portion 4 are also equal to each other. Each filler 3 is filled with a non-magnetic material 5 made of synthetic resin, and the entire outer peripheral surface of the non-magnetic material 5 and the entire outer peripheral surface of the convex portion 4 is coated with copper plating 6.

A permanent magnet 7 is disposed on the outer circumference side of the piston rod 2a, and a magnetic holder 8 is disposed on the other side of the outer circumference of the rod 2a corresponding to the permanent magnet 7. The axial length [7] of the permanent magnet 9 is equal to the sum of the axial length L3 of the groove 3 and the axial length L4 of the convex portion 4.

As shown in FIG. 3, 16 holding holes 9 are formed in the magnetic material holder 8, and on one side 8a of the holder 8 opposite to the rod 2a, the opening 9a of each holding hole 9 has 3 holes. They are arranged in staggered rows.

Magnetic sensing bodies M1 to M16 are inserted into each holding hole 9, and are arranged in parallel in the axial direction at the same pitch P so that one end thereof faces the convex portion 4 and the groove 3. Each of the magnetic sensing bodies M1 to M16 is formed by winding a coil 11 around a magnetic body 10 (core), as shown in FIG.

As shown in FIG. 4, the magnetic permeability μ of each magnetic body 10 decreases as the magnetic bias becomes stronger due to the magnetic force G (Gauss) applied from the outside. The magnetic material 10 is preferably a material with a large magnetic permeability μ (and a small coercive force), such as an amorphous alloy or a permalloy alloy. Examples of amorphous alloys include those with a magnetic permeability μ of 14000 and a coercive force of 0.2 G. The diameter of the cross-sectional shape of the magnetic body 10 is suitably Q, about 1 mm.

Also, the pitch P between each magnetic sensing body M1 to M16 is 0°2m.
It has become m.

As shown in FIG. 5, an oscillator 12 is connected to the coil 11 of each of the magnetic sensing bodies M1 to M16. 100 kl- from this oscillator 12 to each coil 11.
A sine waveform of 17 is applied to 1z to 500 to cool down. Furthermore, resistors R1 to R16 are connected in series to the coils 11 of the magnetic sensing bodies M1 to M16, respectively, so that the voltage across each resistor (1 to R16) can be taken out by the operational amplifier 14. The output signals from the operational amplifiers 14 are guided to latch circuits 15 each consisting of a flip-flop, and are oscillated for one cycle in synchronization with the output of the oscillator 12 by a start pulse or a reset pulse from a timing generation circuit 16 connected to the output 12. The output signal from the latch circuit 15 is a code signal corresponding to the position of the rod 2a, and is fed to a code conversion circuit 17 consisting of a logic circuit. After being converted into a binary signal by 17, it is taken out via an amplifier 18.

The magnetic body 10 made of an amorphous alloy receives a magnetic force of about 10 G at the convex portion 4 of the rod 2a having a large diameter, and when the diameter of the rod 2a is small, the magnetic force becomes 3 G or less. This magnetism (A10 has a permeability μ of 14000 or more,
At a magnetic force of 5G or more, the 'f1 magnetic flux μ decreases rapidly. The inductance of the coil 11 wound around this magnetic material 10 similarly changes rapidly as the magnetic permeability μ changes. A voltage change occurs in the resistors R1 to R16 connected in series to the coil 11 in accordance with a change in inductance. The state of this voltage change is shown in FIG. 6, and in response to the applied waveform from the oscillator 12, the coil detection waveform shown in the figure is output to the coil 11 of each magnetic sensor M1 to M16.

In state 1 shown in FIG. 2, resistors [)1 to R
At the same time, a high-level voltage is generated at the resistors R9 to R16 connected in series to the magnetic sensing bodies M9 to M16 corresponding to the third rods 2a, and this high-level voltage and the low-level voltage are generated Threshold 1 between the voltages
The hold level is an ON-OFF digital signal. This digital signal is taken out as a binary output by the latch circuit 15 and code conversion circuit 17. Note that since the rod 2a usually has a length of 100 mm or more, it is possible to deal with a better rod 2a by adjusting the binary output.

FIG. 1 shows an example in which the position detection device 1 configured as described above is applied to the positioning control of the air cylinder 2, and the above-mentioned binary output is fed back to the controller 19. The positioning of the air cylinder 2 is controlled by controlling the electromagnetic valve 20 through a decoding process.

In particular, in this embodiment, the movement 1! of the rod 2a is used as a means for detecting the position of the rod 2a in which a plurality of grooves 3 are arranged in parallel in the axial direction. +Permanent magnet 7 that applies a magnetic field on the trajectory
By arranging a plurality of magnetic bodies 10 in parallel in the axial direction of the rod 2a correspondingly, changes in the magnetic field accompanying the movement of the rod 2a are detected as changes in the magnetic permeability μ of the magnetic body 10. The rod 2a itself can be used as a scale to directly detect the position using the plurality of magnetic bodies 10, and the position detection device can be made simple and compact. In addition, multiple! In this embodiment, as a means for detecting changes in the magnetic permeability μ of each magnetic body 10, changes in the inductance of the coil 11 wound around each magnetic body 10 are detected as a digital signal.

Moreover, since an amorphous alloy is used as the magnetic material 10, minute displacement of the rod 2a (for example, 0.1ml1
), a large change in magnetic permeability μ can be obtained, and it can be changed up to the saturation region, making it possible to reduce a large electrical output by 1.

Effects of the Invention According to the present invention, changes in the magnetic field of the magnet acting on the movement locus of the movable rod can be observed through a plurality of magnetic bodies. Since the change is detected as a change in 1f8, the structure of the position detection device is simplified.

[Brief explanation of the drawing]

FIG. 1 is a system block diagram using a position detection device according to an embodiment of the present invention, FIG. 2 is a partial sectional view showing the position detection device, FIG. 3 is a perspective view showing a magnetic material holder, and FIG.
The figure is a graph showing the relationship between magnetic force and magnetic permeability, and Figure 5 shows the permeability of magnetic materials! FIG. 6 is a detection circuit diagram for detecting a change in the rate of 1, and is a waveform diagram showing the waveforms applied to the coils wound around each magnetic material and the detected waveforms of each coil. DESCRIPTION OF SYMBOLS 1... Position detection device, 2a... Piston rod (movable rod), 3... Groove, 7... Permanent magnet, 10...
- Magnetic material, 11... Coil, M1-M16... Magnetic sensing body, μ... Magnetic permeability, R1-R16... Resistance. Magnetic force G

Claims (1)

[Claims] 1. A movable rod having a plurality of grooves (3) arranged in parallel in the axial direction (
2a), a magnet (7) that applies a magnetic field on the movement locus of the movable rod (2a), and a plurality of magnetic bodies arranged in parallel in the axial direction of the movable rod (2a) in correspondence with the magnet (7). (10); and a detection means for detecting a change in the magnetic field accompanying the movement of the movable rod (2a) as a change in magnetic permeability (μ) of the magnetic body (10). Device. 2. In the first claim, the detection means includes each magnetic body (10).
A position detection device characterized in that a coil (11) is wound around the coil (11) and a change in inductance of each coil (11) is detected. 3. The position detecting device according to claim 1, wherein the detecting means detects as a digital signal.