JPH11108605A - Non-contact linear displacement sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized linear displacement sensor which can detect the linear displacement of an object with high accuracy, can be used for hydrau lic cylinders, and has a simplified structure. SOLUTION: A non-contact linear displacement sensor A comprises a sensor main body 10 and a driving means for the main body 10. The main body 10 is composed of a main body frame 13, a slider 11 which is housed in the frame 13, mounted with a permanent magnet, and moves in the axial direction of the frame 13, and a galvanomagnetic transducer section 12 which is fixed on a mounting base 15 closely to the slider 11. The driving means is provided with a connecting wire 5 one end of which is fixed to the slider 11, a triangular plate 4 attached to the other end of the wire 5, a compression spring 3 one end of which is attached to the frame 13, and a spring retainer 8 attached to the other end of the spring 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact linear displacement sensor using a Hall IC, and more particularly to a sensor having a high measurement accuracy, a small size and a low cost, and a simplified configuration.

[0002]

2. Description of the Related Art Conventionally, a potentiometer 50 as shown in FIG. 10 has been used for measuring a linear displacement amount in various devices. In the figure, reference numeral 50a denotes a closed cylindrical metal cover, and an insulating substrate 51 having a substantially rectangular cross section is attached to the inside thereof by a fastener.
On the insulator substrate 51, a resistor 52 and a conductor 53 are provided.
Are extended in parallel. A shaft 54 is inserted into the center of the metal cover 50a, and has a rectangular slider 56 to which a sliding contact 55 is attached. A guide rod 57 is pivotally supported so that the slider 56 slides linearly. When the sliding contact 55 makes contact with the resistor 52 and the conductor 53, respectively, the slider 56 and the substrate 5 are moved.
1 is kept constant.

[0003] The potentiometer thus constructed is mounted on a movable part of various equipment, and is provided with a shaft 5.
A movable part (not shown) is connected to the tip of
The sliding contact 55 attached to the slider 56 slides on the resistor 52 and the conductor 53 by the reciprocating motion of 4. Since the voltage of the resistor 52 also changes with this sliding, the voltage value is read to determine the position of the sliding contact point 55, that is, the stroke position of the movable portion.

As shown in FIG. 11, a non-contact displacement sensor 60 for hydraulic pressure using an MR element which is a magnetoresistive element is used in a place where a working environment such as a hydraulic cylinder of a construction machine is severe. I was In the figure, reference numeral 61 denotes a cylindrical metal case, and a mounting portion 61a having a thread formed thereon.
And is screwed to a plunger of a hydraulic cylinder.
A reciprocating shaft 62 is inserted through the case 61, and a tip of the shaft 62 is a spool 63 of a hydraulic cylinder.
, And a tapered portion 62a is formed on the rear end side of the shaft 62. Terminals 64 and 65 having spring properties sandwiching the tapered portion 62a are connected to the pressure-resistant connector 6.
6 and the terminal 64 has an MR element 6
6, and a permanent magnet 67 is attached to the terminal 65 so as to be close to the MR element 66. Further, the MR element 66 is connected to a substrate 68, and the substrate 68 to which the circuit components are attached is attached to a housing 69 together with a circuit section 68 a attached to the substrate 68. The circuit section 68a is sealed in a filler 70 such as a silicon gel and protected from humidity and mechanical vibration.

[0005] The non-contact type displacement sensor 60 thus configured follows the shaft 62 following the reciprocation of the spool 63.
Also, when the terminals 64 and 65 are pushed apart by the tapered portion 62a of the shaft 62 and the relative position between the magnet 67 and the MR element 66 changes, the magnetic resistance of the MR element 66 changes. The change in the output voltage due to the change in the magnetic resistance is amplified by the substrate 68 and the circuit section 68a, and the position of the shaft 62, that is, the stroke position of the spool 63 is determined by reading the amplified change in the output voltage. .

[0006]

However, in the potentiometer 50 described above, the sliding contact 55 moves together with the movable part of the measuring instrument, so that a movable range corresponding to the stroke is required, and a costly resistor element is required. 52 and conductor 5
The electrode portion 3 needs to be larger than the stroke in order to allow dimensional margins at both ends of the stroke. When the measuring device becomes large, the potentiometer also becomes large, and the expensive resistor required for this is required. 52 and conductor 5
3 also has a problem that the cost is extremely high because the size is large. In addition, when the device is used in a place with bad environment such as generating dust, high temperature and high humidity, or sulfide gas, even if the closed metal cover 50 is used, the metal cover 50 may be used for a long time. Dust, humidity, gas, and the like enter the inside and adhere to the resistor 52 and the conductor 53, thereby causing poor contact with the sliding contact 55, and the position of the movable part of the device is accurately determined. The problem that detection became impossible occurred.

Also, in the non-contact type displacement sensor 60, since the shaft 62 moves together with the spool 63 of the hydraulic cylinder, a movable range corresponding to the stroke of the spool is required. Space is required and the stroke size is further increased, so that the place where the non-contact type displacement sensor 60 is mounted is limited. Further, the MR element 66
A power supply circuit, an amplifying circuit, a temperature compensating circuit, and the like are required for the substrate 68 and the circuit portion 68a for amplifying the output of the circuit 68, and the number of circuit components for the circuit is increased. It takes time and labor to assemble the circuit part 68a with the non-contact displacement sensor 60.
There was also a problem that the cost of the system increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a simple and small linear displacement sensor which is small, has high accuracy, and can be used for a hydraulic cylinder. .

[0009]

In order to solve the above-mentioned problems, the present invention comprises a sensor main body and a driving means for the sensor main body, wherein the sensor main body includes a main body frame, and a permanent magnet provided inside the main body frame. A slider attached to the slider and movable in the axial direction in the main body frame; and a magnetoelectric converter fixed to a mounting base in close proximity to the slider, wherein the driving means has one end fixed to the slider. A connection wire, a triangular plate attached to the other end of the connection wire, a compression spring having one end attached to the body frame, and a spring retainer attached to the other end of the compression spring.

Further, the slider is characterized in that two permanent magnets are mounted with opposite poles opposite to each other by a predetermined distance and slide along a guide pin parallel to the main body frame. . Further, the magnetoelectric conversion section includes a Hall element, a temperature compensation circuit, and an amplification circuit therein, and is formed as an IC. Further, the triangular plate is formed in a substantially triangular shape by a metal plate having a spring property, and a support portion of the compression spring is formed and bent near each vertex, and one of the support portions is bent at its tip in an arc shape. It is fixed to the compression spring, and the other two ends of the support portion are formed in a V-shape to support an intermediate portion of the compression spring.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings. 1 is a perspective view showing a general non-contact linear displacement sensor according to the present invention, FIG. 2 is a sectional view of the non-contact linear displacement sensor of FIG. 1, and FIG. 3 is a shaft of the non-contact linear displacement sensor of FIG. FIG. 4 is a perspective view of the triangular plate of the non-contact linear displacement sensor of FIG. 1, FIG. 5 is a cross-sectional view of the sensor body of the non-contact linear displacement sensor of FIG. 1, and FIG. Is a schematic diagram showing a magnetoelectric conversion unit of the non-contact linear displacement sensor of FIG. 1, FIG. 7 is a graph showing characteristics of the non-contact linear displacement sensor of FIG. 1, and FIG. FIG. 9 is a schematic view showing the operation, and FIG. 9 is a sectional view showing a non-contact linear displacement sensor for hydraulic pressure according to the present invention.

As shown in FIGS. 1 and 2, a non-contact linear displacement sensor A for general use according to the present invention has a main body frame 13 of a sensor main body 10 attached to a rear end of a cylindrical case 1. A shaft 2 projecting from the tip of the case 1
However, when the movable part of the measurement object (not shown) is reciprocated and displaced, the triangular plate 4 is reduced by being received by the compression spring 3.
, And the displacement of the triangular plate 4 is transmitted through the connection wire 5 to displace the slider 11 of the sensor body 10, whereby the permanent magnet 11 mounted on the slider 11 is displaced.
The positions of a and 11b are detected by the magnetoelectric conversion unit 12.

The case 1 is formed of a non-magnetic cylindrical metal such as aluminum, and has a front plate 6 attached to a front end thereof. The shaft 2 is slidably mounted on the center of the front plate 6. A metal bearing 7 to be penetrated is attached. Further, a body frame 13 of the sensor body 10 is provided at a rear end of the case 1.
A connection terminal 14 for connecting to an external circuit (not shown) is protruded from the rear side surface of the sensor body 10, or a lead wire is drawn out.

As shown in FIG. 2, a spring retainer 8 is attached to the end of the shaft 2 inside the case 1, and the distal end 3a of the compression spring 3 is interposed in the spring retainer 8. Accordingly, the distal end portion 3a of the compression spring 3 can move together with the movement amount of the shaft 2. A rear end 3b of the compression spring 3 is fitted into a spring receiving portion 10a of the sensor body 10, and a triangular plate 4 is attached to an intermediate portion near the rear end 3b. Since the triangular plate 4 is contracted by the resilience of the compression spring 3, as shown in FIG. 3, the triangular plate 4 is displaced by a movement amount of 1/10 with respect to the movement amount (stroke) of the shaft 2.

As shown in FIG. 4, the triangular plate 4 is formed in a substantially triangular shape by a metal plate having a spring property, and a support portion for the compression spring 3 is formed near each vertex to be bent. One end of the compression spring 3 is folded back in an arc shape.
A spring holder 4a for fixing the end of the compression spring 3, and the other two ends of the support portion are formed in a V-shape to form spring support portions 4b and 4c for supporting an intermediate portion of the compression spring 3. . The compression spring 3 is fixed by inserting a predetermined portion near the end into a spring retainer 4a of the triangular plate 4 and fixing the middle portion of the compression spring 3 to V-shaped spring support portions 4b and 4c formed at two positions of the triangular plate 4. The valleys are supported so that they can be loosely fitted. The triangular plate 4 prevents the compression spring 3 from changing its inclination depending on the degree of compression and adversely affecting the stroke. A hole 4d is formed in the center of the triangular plate 4, one end of a connection wire 5 is inserted into the hole 4d, and a spherical bead 5a is attached to the end of the connection wire 5, and the bead 5a is It is held down by a bead holder 4 e formed on the triangular plate 4. Further, the other end of the wire 5 is connected to a hook 18 attached to the slider 11.
Is fixed by soldering or the like.

As shown in FIG. 5, the sensor body 10 attached to the rear end of the case 1 has a body frame 13 of the sensor body 10 attached to the rear end of the case 1 by screws. Has a slider 11 slidably mounted thereon. Further, a mounting base 15 for mounting the magnetoelectric conversion unit 12 is provided in the vicinity of the slider 11.

The slider 11 of the sensor body 10 is formed by blocking two permanent magnets 11a and 11b with opposite poles facing each other and providing a gap at the center thereof by molding. The guide pins 17a and 17b are fixed, and the slider 11 slides along the guide pins 17a and 17b. Two permanent magnets 11a,
By making the opposite poles 11b opposite to each other with a predetermined interval, the center position of the magnetic flux comes to the midpoint between the magnets and becomes clearer than when one magnet is used, and the measurement accuracy is improved. . The rear end of the connection wire 5 is fixed to the front end of the slider 11, so that the slider 11 moves following the movement of the connection wire 5.

The magnetoelectric conversion unit 12 for detecting the displacement of the slider 11 is provided near the
5 is fixed. As shown in FIG. 6, the magnetoelectric conversion unit 12 includes a Hall element 12a therein, and further incorporates an amplifier 12b having a temperature compensation circuit and an amplification circuit into an IC and packaged by molding. Thus, the intensity of the magnetic field can be converted into electric resistance by the Hall element. Since the magnetoelectric converter 12 can measure the distance from the permanent magnets 11a and 11b by the strength of the magnetic field, it is possible to accurately detect the axial displacement of the permanent magnets 11a and 11b without being affected by the temperature of the external environment. Has become.

The magnetoelectric converter 12 has a power supply terminal 12c, an output terminal 12d, and a ground terminal 12e.
These three terminals are connected to the three terminals or the lead wires of the connection terminal 14 of the external circuit, and the output of the magnetoelectric conversion unit 12 is connected to an external circuit (not shown). Can be read. FIG. 7 is a graph showing the relationship between the distance (stroke) between the permanent magnets 11a and 11b read by the magnetoelectric converter 12 and the output voltage. According to this graph, since the stroke, which is the use range, changes linearly between -1.0 to +1.0 mm, a minute displacement can be detected by reading the voltage output from the magnetoelectric conversion unit 12, Highly accurate measurement is possible.

In the non-contact linear displacement sensor A thus configured, the shaft 2 is attached to a movable part of a device (not shown), and is used for detecting the stroke position. The detection operation will be described with reference to FIGS. First, as shown in FIG. 8A, since the shaft 2 is extended by the compression spring 3, the triangular plate 4 attached to the rear end 3b of the compression spring 3 is also displaced. The slider 11 connected to the
a, 17b, the permanent magnets 11a, 11b mounted on the slider 11 are displaced to a voltage of 1.0 V corresponding to a predetermined position (for example, P1 in FIG. 7).
Is generated, the position of the stroke is specified.

Next, as shown in FIG. 8 (b), when the shaft 2 is pushed by a movable part of a device (not shown), the distal end 3a of the compression spring 3 is pushed close to the center of the case 1, so that the compression is performed. The wire 5 fixed to the rear end 3b side of the spring 3 via the triangular plate 4 is pushed, and the slider 11 connected to the wire 5 also moves along the guide pins 17a and 17b and is attached to the slider 11. Permanent magnet 11
a and 11b are displaced to generate a voltage of 4.0 V corresponding to the position of P2 in FIG.
The position of 0 mm can be specified.

As described above, according to the embodiment of the present invention, the amount of movement of the shaft 2 is reduced to 1/1 by the compression spring 3.
Since it is reduced to 0 and transmitted to the triangular plate 4, the displacement of the slider 11 of the sensor body 10 is only 1/10, and the size of the non-contact linear displacement sensor A can be reduced. Also, the slider 11
Since the magneto-electric conversion unit 12 that detects the displacement of the sensor uses a Hall IC that is a non-contact sensor, it can be a long-life, highly accurate, simplified linear displacement sensor.

Next, a non-contact linear displacement sensor B for hydraulic pressure used in a hydraulic cylinder for a construction machine will be described with reference to FIG. The non-contact linear displacement sensor B for hydraulic pressure is such that the sensor main body 10 of the non-contact linear displacement sensor A is directly attached to a plunger such as a hydraulic cylinder using a pressure-resistant connector 20. An O-ring 21 is inserted to prevent oil leakage. Compression spring 3
Of the plunger shaft 2
The triangular plate 4 attached to the compression spring 3 is operated by a 1/10 stroke of the distal end portion 3a of the compression spring 3 by being pressed against the spool 2 and following the spool 22. Further, the slider 11 is displaced by the wire 5 having one end attached to the triangular plate 4, and the slider 11 is displaced.
An output voltage is generated from the magnetoelectric conversion unit 12 by the two permanent magnets 11a and 11b attached to the
More output.

In the non-contact linear displacement sensor B for hydraulic pressure configured as described above, a case is not required, and the sensor body 10 is significantly reduced in size as compared with the conventional one because the magnetoelectric conversion unit 12 is integrated. Since it has a very small dimension protruding from the plunger, it can be effectively used as a hydraulic sensor.

[0025]

The present invention comprises a sensor body housed in a case and driving means for the sensor body, wherein the sensor body has a slider mounted with a permanent magnet and movable in the axial direction of the case, A magneto-electric conversion part fixed to a mounting base in proximity to the slider, the driving means comprising: a connection wire fixed to one end of the slider; and a triangular plate mounted to the other end of the connection wire; The displacement amount of the object to be measured is constituted by a compression spring having one end mounted on the triangular plate, and a shaft fixed to the other end of the compression spring via a spring retainer and sliding in the case in the axial direction. The displacement of the permanent magnet of the sensor body is 1/10
Therefore, it is possible to provide a simple and compact non-contact linear displacement sensor. Further, since an expensive resistor or conductor is not used, the cost can be reduced. In addition, since the sensor body contained in the sealed case is non-contact, a highly reliable and long-life non-contact linear displacement sensor can be provided. Further, since the two permanent magnets are separated from each other by a predetermined distance and the opposite poles are opposed to each other in the slider, the center position to be measured is clarified, and highly accurate measurement can be performed. In addition, the magnetoelectric conversion unit includes a Hall element, a temperature compensation circuit, and an amplification circuit therein, and is integrated into an IC, so that the sensor body is downsized. The size can be reduced and the labor for assembling the circuit unit is not required, so that the cost can be reduced.
Further, the triangular plate is formed into a substantially triangular shape by a metal plate having a spring property, a support portion of the compression spring is formed near each vertex and bent, and one end of the support portion is folded back in an arc shape to form the triangular plate. The compression spring is stabilized by providing a spring retainer for fixing an intermediate portion of the compression spring and forming the remaining two tips of the support portion in a V-shape to serve as a spring support for supporting the intermediate portion of the compression spring. And the inclination of the end due to the degree of compression of the compression spring can be absorbed, so that the measurement accuracy can be improved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a general non-contact linear displacement sensor according to the present invention.

FIG. 2 is a cross-sectional view of the non-contact linear displacement sensor of FIG.

FIG. 3 is a graph showing a stroke of a shaft and a displacement of a triangular plate of the non-contact linear displacement sensor of FIG. 1;

FIG. 4 is a perspective view of a triangular plate of the non-contact linear displacement sensor of FIG.

FIG. 5 is a sectional view of a sensor body of the non-contact linear displacement sensor of FIG. 1;

FIG. 6 is a schematic diagram showing a magnetoelectric converter of the non-contact linear displacement sensor of FIG. 1;

FIG. 7 is a graph showing characteristics of the non-contact linear displacement sensor of FIG. 1;

FIG. 8 is a schematic diagram showing the operation of the non-contact linear displacement sensor of FIG.

FIG. 9 is a sectional view showing a non-contact linear displacement sensor for hydraulic pressure according to the present invention.

FIG. 10 is a partially broken perspective view showing a conventional potentiometer.

FIG. 11 is a sectional view showing a conventional non-contact linear displacement sensor for hydraulic pressure.

[Explanation of symbols]

 A non-contact linear displacement sensor for general use B non-contact linear displacement sensor for hydraulic pressure 1 case 2 shaft 3 compression spring 3a tip 3b rear end 4 triangular plate 4a spring retainer 4b spring support 4c spring support 4d hole 4e bead retainer 5 connection Wire 5a Bead 6 Front plate 7 Metal bearing 8 Spring retainer 10 Sensor body 11 Slider 11a Permanent magnet 11b Permanent magnet 12 Magnetoelectric converter 13 Body frame 14 Connection terminal 15 Mounting base 17 Guide pin 18 Hook 20 Pressure-resistant connector 21 O-ring

Claims (4)

[Claims] 1. A sensor body comprising: a sensor main body; and a driving means for the sensor main body. The sensor main body includes a main body frame, and a slider mounted on the main body frame and having a permanent magnet mounted thereon and movable in the main body frame in an axial direction. And a magnetoelectric conversion section fixed to a mounting base in proximity to the slider, wherein the driving means comprises: a connection wire having one end fixed to the slider; and a triangular plate mounted to the other end of the connection wire. A non-contact linear displacement sensor, comprising: a compression spring having one end mounted on the body frame; and a spring retainer mounted on the other end of the compression spring. 2. The slider according to claim 1, wherein the two permanent magnets are spaced apart from each other by a predetermined distance, are mounted with opposite poles opposite each other, and slide along guide pins parallel to the body frame. 2. A non-contact linear displacement sensor according to item 1. 3. The non-contact straight line according to claim 1, wherein the magnetoelectric conversion unit includes a Hall element, a temperature compensation circuit, and an amplification circuit therein, and is formed as an IC. Displacement sensor. 4. The triangular plate is formed in a substantially triangular shape by a metal plate having a spring property, and a support portion of the compression spring is formed and bent near each vertex, and one end of the support portion has an arc shape. 4. The compression spring is fixed by folding back, and the other two ends of the support portion are formed in a V-shape to support an intermediate portion of the compression spring.
The non-contact linear displacement sensor according to any one of the above.