JPH052005U - Rod position detector - Google Patents

Abstract

(57) [Summary] [Object] The present invention aims to downsize a sensor of a device for detecting rod positions of various actuators and to simplify a signal processing circuit. [Constitution] The width has a maximum width and a minimum width which are alternately repeated at a constant pitch, or the bottom surface is inclined so that the depth continuously increases (angle θ). Position markers 59 having different ratios are attached along the axial direction of the rod 58, and a sensor 60 composed of one electromagnetic coil is provided facing the position markers.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 INDUSTRIAL APPLICABILITY The present invention relates to a device for detecting the rod position of various actuators, and can be applied to hydraulic actuators, electric actuators, valve control actuators of various plants, and the like.

[0002]

[Prior Art]

 Conventionally, for example, a rod position detection device of a hydraulic cylinder has a dissimilar metal having a magnetic characteristic different from the magnetic characteristic of the rod base material, which is intermittently embedded at equal intervals in the axial direction of the rod as a position marker. A method of detecting by a coil arranged on the inner circumference is used, and it is disclosed in Japanese Utility Model Application Publication No. 64-173604 "Eddy Current Rod Position Sensor".

As shown in FIG. 7 and FIG. 8, this device uses a hydraulic cylinder to detect displacement caused by the movement of a dissimilar magnetic metal 9 embedded in a sensing rod 8 with an axial length a equal to a gap b. The detection is performed by the head sensor 10 including two sets of detection coils 10-1 and 10-2, which are arranged with a phase shifted by 1/4 cycle from 1. A displacement detection signal of the dissimilar magnetic metal 9 due to the movement of the sensing rod 8 is output as shown in FIG.

That is, the amount of movement of the sensing rod 8 is detected by the detection value of either one of the detection coils 10-1 or 10-2 or the average of the detection values of both of the detection coils 10-1 and 10-2. The moving direction of the sensing rod 8 is detected by the differential of the detection coils 10-1 and 10-2 (difference in phase change).

[0005]

[Problems to be solved by the device]

 In the conventional device, in order to specify the moving direction of the sensing rod 8, two sets of ring-shaped and large detection coils 10-1 and 10-2 and the detection coils 10-1 and 10-2 output from both of them. A signal processing circuit 12 1 having a moving direction determination unit for processing 11 is required. Therefore, the device becomes complicated and expensive.

[0006]

[Means for Solving the Problems]

 The structure of the actuating rod position detection device according to the present invention for solving the above-mentioned problems is such that the displacement of the position marker in the axial direction of the rod is detected by a sensor fixed facing the position marker, and the axis of this rod is detected. In a device that detects the amount of movement and the direction of movement of the rod, the maximum width and the minimum width are alternately arranged in a row in the long direction, and the bottom surface is formed to be inclined in the longitudinal direction. The base material is characterized in that a position marker made of a substance having a different electrical conductivity is embedded in the axial direction of the rod, and a sensor made of one electromagnetic coil is provided facing the position marker.

[0007]

[Action]

 The sensor is applied to the current to generate an eddy current on the surface of the rod in which the facing position marker is embedded. When the rod moves in the axial direction, the depth due to the bottom slope of the facing position marker changes, and at the same time, the periodic shape arranged in the length direction also changes. The output of the sensor at this time is a combination of the first-order tilt component due to the bottom surface tilt and the periodic component due to the periodic shape change. By combining these two signal components appropriately. (That is, by appropriately determining the bottom surface inclination and the periodic shape of the position marker), the moving direction and the moving amount of the rod can be detected at the same time.

[0008]

【Example】

 Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.

In FIGS. 1 to 3, 59 is a position marker made of a metal having a lower conductivity than the base material of the rod 58, such as nickel chrome alloy, and is a top view of FIG. As shown in, the maximum width w1 and the minimum width w2 are alternately arranged at the same pitch p, and the bottom surface thereof is formed with a slope by the inclination angle θ, and the rod 58 of the rod 58 integrated with the plunger 58a in the cylinder 51 is formed. It is buried in the axial direction. Reference numeral 60 denotes a sensor head composed of one coil, which is embedded at the outlet of the cylinder 51 so as to face the position marker 59 and is connected to the hydraulic servo circuit 53 via a signal processing circuit 62 and a stroke controller 54. .

It should be noted that the surfaces of the rod 58 and the position marker 59 may be plated with Cr of about 20 to 40 μm or the like to prevent abrasion due to sliding of the cylinder 51 on the seal, which does not hinder the measurement. ..

Next, the operation of this device will be described. When a current is applied to the sensor head 60 and the rod 58 and the position marker 59 move due to the movement of the plunger 58a, the widths w1 and w2 of the portion of the position marker 59 facing the sensor head 60 change periodically, and The height h increases or decreases depending on the moving direction. Since the conductivity of the position marker 59 is lower than that of the rod 58, the eddy current generated on the surface of the rod 58 changes due to the axial movement of the rod 58 (widths w1 and w2 of the position marker 59). And the eddy current becomes smaller as the depth h becomes larger.) In comparison, the coil output b1 also changes.

As shown in FIG. 4, the change in the coil output 61 is caused by the change in the periodic component a and the depth h caused by the change in the periodic widths w1 and w2 of the position marker 59. And a first-order gradient component generated as a result.

Therefore, by appropriately determining the amounts of the periodic component and the first-order slope component, the positions of the coil output 61 and the rod 58 can be made to correspond one-to-one, and the sensor head 60 can be connected via the signal processing circuit 62. The position of the rod 58 can be detected from the coil output 61 of the. If the position of the rod 58 needs to be corrected, the correction signal is transmitted to the stroke controller 54, and the stroke controller 54 moves the plunger 58a and the rod 58 via the hydraulic servo circuit 53 according to the received signal. , Control its position.

FIG. 5 shows a width shape of the position marker 69 according to the second embodiment of the present invention, which is a curve connecting the maximum width w1 and the minimum width w2 for the convenience of the work, and the like. The configuration is the same as that of the first embodiment. Even such a width shape does not hinder the detection of the movement amount of the rod 58 due to the change of the periodic component a.

[0015]

[Effect of the device]

 In the present invention, the maximum width and the minimum width embedded in the axial direction of the rod are alternately arranged in the length direction at equal intervals, and the bottom surface is inclined in the length direction so that the position of the material having a different conductivity from the rod is positioned. By simultaneously detecting the moving amount and the moving direction of the marker by the sensor composed of one electromagnetic coil, the sensor becomes a spot-like small size and can be simplified, and the signal processing circuit thereof can also be simplified. Therefore, the cost of the actuator and its associated device can be reduced.

[Brief description of drawings]

FIG. 1 is a conceptual view of a rod position detecting device according to a first embodiment of the present invention and a cutaway side view showing a rod, a position marker and a sensor head.

FIG. 2 is a sectional view taken along the line III-III in FIG.

FIG. 3 is a plan view showing the shape of the position marker shown in FIGS. 1 and 2.

FIG. 4 is a diagram showing a coil output by moving a rod.

FIG. 5 is a plan view showing a width shape of a position marker of a rod position detecting device according to a second embodiment of the present invention.

FIG. 6 is a conceptual diagram showing a conventional rod position detecting device.

FIG. 7 is a conceptual diagram showing a positional relationship between the sensor head of FIG. 6 and a different magnetic metal.

8 is a diagram showing a coil output by moving the rod in FIG. 7. FIG.

[Explanation of symbols]

51 ... Cylinder, 53 ... Hydraulic servo circuit, 54 ... Stroke controller, 58 ... Rod, 59 ... Position marker, 60 ... Sensor head, 62 ... Signal processing circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuo Ideue 4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture Mitsubishi Heavy Industries, Ltd. Hiroshima Research Institute (72) Hiroaki Shimatsutsu 4 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture 6-22 No. 6 Hiroshima Research Center, Mitsubishi Heavy Industries, Ltd.

Claims (1)

Claims for utility model registration Claims 1. The displacement of the axial position marker of the rod is detected by a vertical sensor fixed facing the position marker, and the axial movement amount and movement direction of the rod are detected. In the device for detecting, the maximum width and the minimum width are alternately arranged in a row in the length direction at equal intervals, and the bottom surface is formed to be inclined in the length direction, and the base material of the rod has a conductivity of A rod position detecting device for an actuator, characterized in that a position marker made of a different substance is embedded in the axial direction of the rod, and a sensor constituted by one electromagnetic coil is provided facing the position marker.