JP3822731B2 - Non-contact linear displacement sensor - Google Patents

Description

[0001]
BACKGROUND 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 simplified configuration with high measurement accuracy, small size, and low cost.
[0002]
[Prior art]
Conventionally, a potentiometer 50 as shown in FIG. 10 has been used to measure a linear displacement amount in various devices.
In the figure, reference numeral 50a denotes an airtight cylindrical metal cover, and an insulating substrate 51 having a substantially rectangular cross section is attached to the inside thereof with a stopper. A resistor 52 and a conductor 53 extend in parallel on the insulating substrate 51. A shaft 54 is inserted into the central portion of the metal cover 50a, and a square slider 56 to which the sliding contact 55 is attached is attached.
Further, a guide rod 57 is pivotally supported so that the slider 56 slides linearly, and the distance between the slider 56 and the substrate 51 when the sliding contact 55 moves in contact with the resistor 52 and the conductor 53, respectively. Is kept constant.
[0003]
The potentiometer thus configured is attached to a movable part of various devices, a movable part (not shown) is connected to the tip of the shaft 54, and a sliding contact 55 attached to the slider 56 by reciprocation of the shaft 54. Slides on the resistor 52 and the conductor 53. 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 55, that is, the stroke position of the movable part.
[0004]
Further, as shown in FIG. 11, a hydraulic non-contact displacement sensor 60 using an MR element, which is a magnetoresistive element, is used in a severe working environment such as a hydraulic cylinder of a construction machine or the like.
In the figure, reference numeral 61 denotes a cylindrical metal case, which is screwed to a plunger or the like of a hydraulic cylinder by a mounting portion 61a formed with a thread. A reciprocating shaft 62 is inserted into the metal case 61, the tip of the shaft 62 is pressed against 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 characteristics sandwiching the taper portion 62 a are provided upright from a pressure-resistant connector 66, and an MR element 66 is attached to the terminal 64, and the terminal 65 is permanent so as to be close to the MR element 66. A magnet 67 is attached.
Moreover, MR element 66 is connected to the substrate 68, the substrate 68 the circuit components are mounted is attached to the housing base 69 with the circuit part article 68a which is attached to the substrate 68. Circuit parts 68a are protected from by humidity and mechanical vibrations enclosed within a filler material 70 such as silicone gel.
[0005]
The contactless displacement sensor 60 configured in this manner follows the reciprocating movement of the spool 63 and the shaft 62 also reciprocates. Therefore, the terminals 64 and 65 are expanded by the taper portion 62 a of the shaft 62, and the magnet 67. When the relative position with respect to the MR element 66 changes, the magnetoresistance of the MR element 66 changes. The change in output voltage due to the change of the magnetic resistance is amplified by the substrate 68 and the circuit unit product 68a, by reading the change in the output voltage amplified, the position of the shaft 62, i.e. those that determine the stroke position of the spool 63 is there.
[0006]
[Problems to be solved by the invention]
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 the expensive resistor 52 and the conductor 53 have electrode portions. In order to provide a dimensional margin at both ends of the stroke, it is necessary to make it larger than the stroke, and when the measuring instrument becomes larger, the potentiometer becomes larger, and the expensive resistor 52 and conductor 53 necessary for this increase. There is also a problem that the cost is very high because the size is increased.
Further, when used in a poor environment where dust, high temperature and high humidity, sulfide gas, or the like is generated, the metal cover 50 can be used for a long time even if the sealed metal cover 50 is used. dust and humidity within, and gas or the like from entering, to generate contact failure between the sliding contact 55 so adheres to the resistor 52 and conductor 53, is precisely the position of the movable portion of the device There was a problem that it could not be detected.
[0007]
Also in a contactless type displacement sensor 60, the shaft 62 moves together with the spool 63 of the hydraulic cylinder, requires the movable range of the stroke of the spool, more space for mounting components such as circuit parts 68a Is required, and the size of the non-contact type displacement sensor 60 is limited.
In addition, the substrate 68 and the circuit section article 68a for amplifying the output of the MR element 66, the power supply circuit, amplifier circuit, temperature compensation circuit and the like are required, the circuit components for is increased, the substrate 68 and the circuit section article 68a is with large, man-hours for assembling the board 68 and the circuit unit products 68a-consuming, there is also a problem that eventually the cost of the non-contact type displacement sensor 60 is increased.
[0008]
The present invention has been made to solve the above-described problems, and provides a simplified and small linear displacement sensor that is small in size and high in accuracy, and that can also be used in a hydraulic cylinder.
[0009]
[Means for Solving the Problems]
The present invention in order to solve the above problems, the sensor body (10) includes a body frame (13), the body frame permanent magnets are furnished to (13) (11a, 11b) and is mounted by the body frame (13 ) A slider (11) movable in the axial direction, a magnetoelectric conversion part (12) fixed to the mounting base (15) in the vicinity of the slider (11) , and the slider (11) movable in the axial direction drive means and drive means, said slider (11) which is includes a slider (11) connecting wire of which one end is fixed to (5), the other end of the connection wire (5) is engaging A triangular plate (4) , a compression spring (3) having one end (3b) attached to the body frame (13) and locking the triangular plate (4 ), and the other end (3a) of the compression spring (3) a loaded spring retainer (8) and fixed to the spring retainer (8) axis The triangular plate (4) is formed in a substantially triangular shape by a metal plate, and is connected to the compression spring (3) in the vicinity of each apex (4a, 4b, 4c). ), And one of the locking portions (4a) is bent and fixed at one point of the compression spring (3), and the remaining two (4b) of the locking portions are fixed. , 4c) has a V-shaped tip, so that the triangular plate (4) is slidably locked horizontally to the compression spring (3) at right angles to the axial direction. The locking fixing position of one locking portion (4a) of the triangular plate (4) to one point of the compression spring (3) is the compression spring (3) pushed by the shaft (2). The compression spring (3) received by the spring receiver (10a) with respect to the expansion / contraction stroke of the tip (3a) of A small position stretch stroke in the vicinity of the rear end portion (3b), a non-contact linear displacement sensor, characterized in that.
[0010]
The slider (11) is mounted with two permanent magnets (11a, 11b) separated from each other by a predetermined distance and facing different poles, and slides along a guide pin (17) parallel to the main body frame (13). and to the two permanent magnets (11a, 11b) to vary the opposing distance with respect to the magnetoelectric converting part (12).
The magnetoelectric converter (12) includes a Hall element, a temperature compensation circuit, and an amplifier circuit inside, and is integrated into an IC.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
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 sectional view of the sensor main body of the non-contact linear displacement sensor of FIG. FIG. 7 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 sectional view showing a hydraulic non-contact linear displacement sensor according to the present invention.
[0012]
As shown in FIGS. 1 and 2, a general non-contact linear displacement sensor A according to the present invention has a main body frame 13 of a sensor main body 10 attached to a rear end portion of a cylindrical case 1. The shaft 2 protruding from the tip of 1 is reduced by receiving a displacement of a movable part of a measurement object (not shown) reciprocated by a compression spring 3 to displace the triangular plate 4. The position of the permanent magnets 11 a and 11 b attached to the slider 11 is detected by the magnetoelectric conversion unit 12 by transmitting to the slider 11 via the connection wire 5 and displacing the slider 11 of the sensor body 10.
[0013]
The case 1 is made of a non-magnetic cylindrical metal such as aluminum, and a front plate 6 is attached to the tip of the case 1. A metal that allows the shaft 2 to slidably pass through the center of the front plate 6. A bearing 7 is attached.
Further, a body frame 13 of the sensor body 10 is attached to the rear end portion of the case 1, and a connection terminal 14 for connecting to an external circuit (not shown) protrudes from the rear side surface of the sensor body 10 or a lead wire. Has been pulled out.
[0014]
In addition, as shown in FIG. 2, a spring retainer 8 is attached to the end of the shaft 2 inside the case 1, and the tip 3 a of the compression spring 3 is interposed in the spring retainer 8, so that the shaft The tip 3a of the compression spring 3 can be moved together in accordance with the amount of movement 2.
A rear end portion 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 portion 3b. Since the triangular plate 4 is reduced by the spring property 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.
[0015]
The triangular plate 4, as shown in FIG. 4, is formed in a substantially triangular with a metal plate, the locking portion 4a, 4b, by bending 4c formed on the compression spring 3 in the vicinity of each vertex, the locking portion one 4a is a front end folded in a circular arc shaped engaging fixed at one point of the compression spring 3, and the remaining two 4b of the locking portion, 4c is formed the tip in a V-shaped, which is the The triangular plate 4 is locked to the compression spring 3 so as to be slidable horizontally at a right angle with respect to the axial direction, and one point of the compression spring 3 of one locking portion 4a of the triangular plate 4 The locking and fixing position is in the vicinity of the rear end portion 3b of the compression spring 3 received by the spring receiving portion 10a with respect to the expansion / contraction stroke of the tip portion 3a of the compression spring 3 pushed by the shaft 2. It is a position with a small expansion / contraction stroke.
Since the triangular plate 4 is formed as described above and is locked to the compression spring 3 as described above, the inclination of the triangular plate 4 changes depending on the degree of compression of the compression spring 3 and adversely affects the stroke. It is to prevent.
In addition, a hole 4d is formed at the center of the triangular plate 4, and one end of the connection wire 5 is inserted into the hole 4d, and a spherical bead 5a is attached to the end of the connection wire 5. The bead presser 4e formed on the triangular plate 4 is pressed. Further, the other end of the wire 5 is fixed to a hook 18 attached to the slider 11 by soldering or the like.
[0016]
As shown in FIG. 5, the sensor main body 10 attached to the rear end of the case 1 has a main body frame 13 of the sensor main body 10 attached to the rear end of the case 1 with screws, and a slider 11 is provided inside the main body frame 13. Is slidably mounted.
In addition, a mounting base 15 for mounting the magnetoelectric conversion unit 12 in the vicinity of the slider 11 is provided.
[0017]
The slider 11 of the sensor main body 10 is formed by blocking two permanent magnets 11 a and 11 b with different poles facing each other and providing a gap at the center portion with a mold. Two guides are provided at the rear end of the sensor main body frame 13. The pins 17a and 17b are fixed, and the slider 11 slides along the guide pins 17a and 17b.
By making the two permanent magnets 11a, 11b face each other with a predetermined gap, the center position of the magnetic flux comes to the midpoint position between the magnets and becomes clearer than when one magnet is used. Accuracy is improved.
The rear end portion of the connection wire 5 is fixed to the front end of the slider 11, and the slider 11 is configured to move following the movement of the connection wire 5.
[0018]
The magnetoelectric conversion unit 12 that detects the displacement of the slider 11 is fixed to the mounting base 15 in the vicinity of the slider 11.
As shown in FIG. 6, the magnetoelectric conversion unit 12 includes a hall element 12 a inside, and further, an amplifier 12 b including a temperature compensation circuit and an amplifier circuit is incorporated into an IC and packaged in a mold. Thus, the Hall element can convert the strength of the magnetic field into electric resistance. Since the magneto-electric conversion unit 12 can measure the distance from the permanent magnets 11a and 11b by the strength of the magnetic field, the axial displacement of the permanent magnets 11a and 11b can be accurately detected regardless of the temperature of the external environment. It has become.
[0019]
The magnetoelectric converter 12 is provided with three terminals, a power supply terminal 12c, an output terminal 12d, and a ground terminal 12e. These three terminals are the connection terminals 14 of the external circuit. Are connected to the three terminals or lead wires so that the output of the magnetoelectric converter 12 can be read by an external circuit (not shown).
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, fine displacement can be detected by reading the voltage output from the magnetoelectric converter 12, Highly accurate measurement is possible.
[0020]
In the non-contact linear displacement sensor A configured as described above, the shaft 2 is attached to a movable part of a device (not shown) and 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 side of the compression spring 3 is also displaced. Since the slider 11 connected to 5 also moves along the guide pins 17a and 17b, the permanent magnets 11a and 11b mounted on the slider 11 are displaced to correspond to a predetermined position (for example, P1 in FIG. 7). Since a voltage of 1.0V is generated, the position of the stroke is specified.
[0021]
Next, as shown in FIG. 8B, when the shaft 2 is pushed by a movable part of a device (not shown), the distal end portion 3 a of the compression spring 3 is pushed to the vicinity of the center portion of the case 1. The wire 5 fixed via the triangular plate 4 is pushed to the rear end 3b side, and the slider 11 connected to the wire 5 is also moved along the guide pins 17a and 17b and is attached to the slider 11. Since the permanent magnets 11a and 11b are displaced to generate a voltage of 4.0 V corresponding to the position of P2 in FIG. 7, the position of +1.0 mm of the stroke can be specified.
[0022]
As described above, according to the embodiment of the present invention, the amount of movement of the shaft 2 is reduced to 1/10 by the compression spring 3 and transmitted to the triangular plate 4, so that the displacement amount of the slider 11 of the sensor body 10 is 1. / 10, and the contactless linear displacement sensor A can be downsized.
In addition, since the magnetoelectric conversion unit 12 that detects the displacement of the slider 11 uses a Hall IC that is a non-contact sensor, a long-life, high-precision, simplified linear displacement sensor can be obtained.
[0023]
Next, a non-contact linear displacement sensor B for hydraulic pressure used for hydraulic cinders such as construction machines will be described with reference to FIG.
The non-contact linear displacement sensor B for hydraulic pressure is obtained by directly attaching the sensor body 10 of the non-contact linear displacement sensor A to a plunger such as a hydraulic cylinder using a pressure-resistant connector 20. An O-ring 21 is inserted to prevent oil leakage.
The tip 3 a of the compression spring 3 is directly brought into pressure contact with the spool 22 of the plunger shaft and operates following the spool 22, so that the triangular plate 4 attached to the compression spring 3 is connected to the tip 3 a of the compression spring 3. It operates with a stroke of 1/10.
Further, the slider 11 is displaced by the wire 5 having one end attached to the triangular plate 4, and an output voltage is generated from the magnetoelectric conversion unit 12 by the two permanent magnets 11 a and 11 b attached to the slider 11 and output from the connection terminal 14. To do.
[0024]
The hydraulic non-contact linear displacement sensor B configured in this way does not require a case, and the magnetoelectric conversion unit 12 is integrated with an IC, so the sensor body 10 is significantly smaller than the conventional one. Since the dimension protruding from the plunger is extremely small, it can be used effectively as a hydraulic sensor.
[0025]
【The invention's effect】
According to the present invention, a sensor main body includes a main body frame, a slider mounted in the main body frame and mounted with a permanent magnet and movable in the axial direction in the main body frame, and a magnetoelectric unit fixed to a mounting base in the vicinity of the slider. a conversion unit, and a driving means for said slider is movable in the axial direction, the driving means of said slider, a connecting wire having one end fixed to the slider, the triangular plate to which the other end of the connection wire is engaging A compression spring in which one end is attached to the main body frame and the triangular plate is locked, a spring retainer in which the other end of the compression spring is attached, and an axially movable shaft fixed to the spring retainer, The triangular plate is formed in a substantially triangular shape by a metal plate, and is formed by bending a locking portion to the compression spring in the vicinity of each apex, and one of the locking portions has its tip folded back in an arc shape. Lock to one point The remaining two of the locking portions have V-shaped tips, which are locked to the compression spring so that the triangular plate is perpendicular to the axial direction and can slide horizontally. The locking fixing position of one locking portion of the triangular plate to one point of the compression spring is a spring with respect to the expansion / contraction stroke of the distal end portion of the compression spring pushed by the shaft. Since the position of the expansion / contraction stroke is small in the vicinity of the rear end portion of the compression spring received by the receiving portion, the displacement amount of the permanent magnet of the sensor body can be reduced to 1/10 with respect to the displacement amount of the object to be measured. The contactless linear displacement sensor reduced in size can be provided.
Further, since expensive resistors and conductors are not used, the cost can be reduced.
Further, since the sensor main body housed in the sealed case is non-contact, a highly reliable long-life non-contact linear displacement sensor can be provided.
In addition, since the slider has two permanent magnets separated from each other by a predetermined distance to face different poles, the center position to be measured is clarified, and high-precision measurement can be performed.
In addition, the magnetoelectric converter has a Hall element, a temperature compensation circuit, and an amplifier circuit inside, and since it is integrated into an IC, the sensor body is miniaturized, thus simplifying the entire contactless linear displacement sensor. since time is not required for assembling the circuit unit products it is possible to miniaturize, it is possible to reduce the cost.
Further, the triangular plate, the metallic plate formed in a substantially triangular, bent to form an engagement portion of the compression spring in the vicinity of each vertex, the compressed folded one tip of the locking portion in an arc shape No intermediate portion of the spring to lock the fixed and the remaining two tips of the engaging portion is formed in a V-shape, which in a sliding horizontally the triangular plate is at right angles to the axial direction Since the triangular plate can be stably attached to the compression spring and the inclination of the triangular plate due to the degree of compression of the compression spring can be absorbed, the measurement accuracy can be increased.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a general non-contact linear displacement sensor according to the present invention.
2 is a cross-sectional view of the non-contact linear displacement sensor of FIG.
FIG. 3 is a graph showing a shaft stroke and a displacement amount of a triangular plate of the non-contact linear displacement sensor of FIG. 1;
4 is a perspective view of a triangular plate of the non-contact linear displacement sensor of FIG. 1. FIG.
5 is a cross-sectional view of a sensor main body of the non-contact linear displacement sensor in FIG.
6 is a schematic diagram showing a magnetoelectric conversion unit of the non-contact linear displacement sensor of FIG. 1;
7 is a graph showing characteristics of the non-contact linear displacement sensor of FIG.
8 is a schematic diagram showing the operation of the non-contact linear displacement sensor of FIG.
FIG. 9 is a cross-sectional view showing a hydraulic non-contact linear displacement sensor according to the present invention.
FIG. 10 is a partially broken perspective view showing a conventional potentiometer.
FIG. 11 is a cross-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 holder 4b Spring support 4c Spring support 4d Hole 4e Bead press 5 Connection Wire 5a Beads 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 (3)

The sensor body (10) includes a body frame (13), a slider (11 to movable main body frame (13) is furnished to permanent magnets (11a, 11b) the main body frame and mounted inside (13) in the axial direction ) , A magnetoelectric conversion part (12) fixed to the mounting base (15 ) in the vicinity of the slider (11) , and a drive means for moving the slider (11) in the axial direction ,
Said drive means of the slider (11) includes a slider (11) connecting wire of which one end is fixed to (5), the triangular plate whose other end is engaging the connecting wires (5) and (4), said body A compression spring (3 ) in which one end (3b) is attached to the frame (13) and the triangular plate (4) is locked; and a spring retainer (8) in which the other end (3a) of the compression spring (3 ) is attached. And the axially movable shaft (2) fixed to the spring retainer (8),
The triangular plate (4) is formed in a substantially triangular shape by a metal plate, and is formed by bending a locking portion (4a, 4b, 4c) to the compression spring (3) in the vicinity of each apex. One (4a) has its tip folded back in an arc shape and is locked and fixed at one point of the compression spring (3), and the remaining two (4b, 4c) of the locking portion are formed with a V-shaped tip. The triangular plate (4) is locked to the compression spring (3) so as to be perpendicular to the axial direction and slidable horizontally.
The locking fixing position of one locking portion (4a) of the triangular plate (4) to one point of the compression spring (3) is the tip of the compression spring (3) pushed by the shaft (2). It is a position where the expansion stroke is small in the vicinity of the rear end portion (3b) of the compression spring (3) received by the spring receiving portion (10a) with respect to the expansion stroke of (3a).
A non-contact linear displacement sensor characterized by that. The slider (11) is mounted with two permanent magnets (11a, 11b) separated from each other by a predetermined distance and facing different poles, and slides along a guide pin (17) parallel to the main body frame (13). and to the two permanent magnets (11a, 11b) to vary the opposing distance with respect to the magnetoelectric converting part (12),
The contactless linear displacement sensor according to claim 1. The non-contact linear displacement sensor according to claim 1 or 2, wherein the magnetoelectric converter (12) includes a Hall element, a temperature compensation circuit, and an amplifier circuit inside and is formed as an IC. .

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