JP3161399U - Pointer reader - Google Patents

Abstract

The present invention provides a pointer reading device that is easy to mount and can accurately read a pointer indication value remotely. A magnet 71 is provided on the front side of a rotation center portion 30 of the pointer 3 so that the direction of the magnetic pole rotates in conjunction with the rotation of the pointer 3, and the pointer 3 rotates opposite to the magnet 71. A plurality of Hall elements 72 having different magnetic field detection directions are arranged adjacent to each other on a plane parallel to the plane, the measurement circuit unit 73 is connected to the Hall element 72, and the Hall element 72 and the measurement circuit unit 73 are exchanged transparent plates. The pointer reading device 7 is configured by being attached to 74. And the measurement circuit part 73 was set as the structure which calculates the signal output from the Hall element 72, and outputs the electrical signal corresponding to the rotation angle of the pointer 3. Therefore, it is not necessary to replace the detector main body 1, the pointer 3, the scale plate 2, and the internal mechanism 12 installed at the site. [Selection] Figure 2

Description

  The present invention relates to a pointer reading device applied to an aneroid type detector having a pointer and a scale plate.

In the process apparatus, various types of detectors such as a mechanical pressure gauge and a differential pressure gauge are used. For example, in order to monitor the liquid level in the liquid storage tank, a differential pressure gauge that measures the differential pressure above and below the tank and detects the liquid level, that is, a differential pressure level gauge is used. There is an advantage that the liquid level of the tank, which is a state quantity, can be read and monitored from the outside even without it.
On the other hand, there is a desire to remotely monitor the pressure gauge reading without adding or replacing a new electric pressure sensor to these existing process equipment. A remote reading device of values has been devised.

As a pointer reading value remote reading device, for example, an electric value converter for converting rotation into an electric value is provided on the front glass provided on the front surface of the pointer and the scale plate, and a follow-up axis which is a rotation axis of the electric value converter is provided. The guide is connected to the drive arm, and a guide that engages the tip of the pointer is formed at the tip of the drive arm so that the rotation of the pointer is directly transmitted to the drive arm, and the rotation of the drive arm is detected by an electric value converter. There is a pointer reading device (Patent Document 1).
In addition, a magnet is attached to each of the tip side and the rear side away from the rotation axis of the pointer, and a rotor having a shape similar to the pointer is connected to a pulse motor disposed opposite to the pointer, and the pointer side magnet is connected to the rotor. There is a pointer reading device that mounts magnets facing each other, transmits the rotation of the pointer to the rotor via the magnetic force of the magnets facing each other, and reads the rotation of the rotor with a pulse motor (Patent Document 2).
Further, a magnet is attached to the tip side from the rotating shaft of the pointer, and a plurality of hall elements are arranged side by side on the back surface of the glass plate positioned on the annular movement line of the magnet as the pointer rotates, and the position of the magnet on the pointer side There is a device that detects this with a Hall element (Patent Document 3).

CD-ROM of Japanese Patent Application No. 62-200787 (Japanese Utility Model Publication No. 1-102996) CD-ROM of Japanese Patent Application No. 3-36516 (Japanese Utility Model Publication No. 4-123499) CD-ROM of Japanese Patent Application No. 2-125315 (Japanese Utility Model Publication No. 4-85111)

In the conventional examples shown in Patent Document 1 and Patent Document 2, a rotating body such as an electric value converter or a pulse motor that is rotationally driven by the movement of the pointer is added, which becomes a load of the movement of the pointer, There is a problem that the error of the value tends to increase.
In the conventional example shown in Patent Document 3, since the magnet is attached with the rotation center of the pointer removed, the weight of the magnet becomes an unbalanced load of the pointer, which affects the movement of the pointer, and the error of the indicated value increases. There is a problem that it is easy.

  An object of the present invention is to provide a pointer reading device that is easy to mount and can accurately read a pointer indication value remotely.

  In the pointer reading device of the present invention, a scale plate is provided on the detector body, and the pointer plate of the detector is replaced by replacing the transparent plate that covers the front of the aneroid type detector having a pointer that rotates on the scale plate. A pointer reading device that electrically converts a dynamic displacement, the magnet being provided on the front side of the center of rotation of the pointer and rotating in conjunction with the direction of the magnetic pole with respect to the rotation of the pointer, Oppositely arranged on a plane parallel to the rotation surface of the pointer and having different magnetic field detection directions, signals output from these magnetic sensors are calculated to calculate the rotation of the pointer. A measurement circuit unit that outputs an electrical signal corresponding to a moving angle, a magnetic sensor and the measurement circuit unit are provided, and a replacement transparent plate that can be attached to the detector body is provided.

In the present invention with this configuration, in order to mount the pointer reading device to the detector, first, the transparent plate mounted on the detector body is removed, a magnet is attached to the center of rotation of the pointer, and the magnetic sensor and measurement circuit A replacement transparent plate, to which a magnetic orientation sensor including a portion is mounted in advance, is attached to the detector body.
For this reason, in the present invention, by replacing the transparent plate with a replacement transparent plate and attaching the magnet to the pointer that is exposed when the transparent plate is removed, the pointer reader can be easily attached. That is, it is not necessary to replace the detector main body installed at the site. Further, since the magnet is installed at the center of rotation of the pointer, the pointer is not subjected to a load due to an offset load.
After the pointer reading device is attached to the detector, normal detection can be performed. That is, when the pointer of the detector rotates with a change in physical quantity such as pressure, the magnet provided on the pointer rotates, and the rotation angle is detected by the magnetic azimuth sensor. As a result, the movement of the pointer can be visually read on the scale plate in a non-contact state with the pointer as well as the movement of the pointer is taken out as an electric signal, so that the pointer indication value can be read remotely.

Here, in the present invention, the magnet is fixed in a magnetic orientation with respect to the magnet fixture, and the magnet fixture can be attached to and detached from the pointer. The first side portion located at the first side portion is set to have a larger width than the second side portion located at the distal end side of the pointer, and the magnet fixture is fitted to the first side portion. It is preferable to include a joint portion and a second fitting portion that fits to the second side portion, and in the vicinity of the outer periphery of the replacement transparent plate, a marking corresponding to the magnetic field detection direction of the magnetic sensor is provided. .
In the present invention having this configuration, since the magnetic orientation of the magnet is determined in advance with respect to the magnet fixture, the magnet orientation is uniquely determined with respect to the orientation of the pointer simply by attaching the magnet fixture to the pointer. The magnet can be easily mounted so that the orientation is right.
Furthermore, the magnetic orientation sensor can correctly measure the orientation of the pointer relative to the scale plate by setting the marking position of the replacement transparent plate so that it is in a specific direction of the scale plate of the detector. A correct indication value is obtained as an electrical signal.

It is preferable that an elastic member for urging the magnet toward the magnet fixture is provided between the center of rotation of the pointer and the magnet.
In the present invention having this configuration, since the magnet is biased and positioned by the magnet fixing member by the elastic member, the pointer rotates together with the magnet, and the detection accuracy of the detector can be increased. .

The magnet fixing tool preferably includes a cover that covers the magnet and a hook that is provided on the cover and is engaged with the back side of the pointer.
In the present invention having this configuration, the magnet can be prevented from being accidentally removed from the pointer by the cover and the hook, so that the detection accuracy of the detector can be increased.

A bottomed cylindrical sensor case that covers the peripheral edge of the opening formed in the replacement transparent plate, and a support member that is provided in the sensor case and the opening of the replacement transparent plate and supports the measurement circuit unit The sensor case includes a bottom portion in which a through hole through which a cable having one end connected to the measurement circuit portion is formed, and a cylindrical portion in which an opening end portion is sealed by the replacement transparent plate. The structure which has is preferable.
In the present invention with this configuration, the sensor case is sealed with the replacement transparent plate, so that the main part of the detector is hardly affected by the outside, and the detection accuracy of the detector can be prevented from being lowered.

The exploded perspective view of the detector incorporating the pointer reading device concerning one embodiment of the present invention. Sectional drawing of the detector incorporating the said pointer reader. The disassembled perspective view of the principal part of the said pointer reader. The disassembled perspective view which shows the position of a magnet fixing tool and a magnet. The back view which shows the state in which the magnet fixing tool was attached to the pointer. The graph which shows the relationship between the rotation angle of a magnet, and the output voltage of a Hall element. The graph which shows the relationship between the rotation angle of a magnet, and the output voltage with respect to a power supply voltage.

An embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is an exploded perspective view of a detector incorporating the pointer reading device according to the present embodiment, and FIG. 2 is a cross-sectional view thereof.
1 and 2, the detector of the present embodiment is an aneroid type pressure gauge installed in a liquid storage tank, and includes a detector main body 1, a scale plate 2 provided on the detector main body 1, and the scale. A pointer 3 that pivots on the plate 2, a transparent plate 4 that covers the front of the pointer 3 and the scale plate 2, a cover 5 that covers the outer peripheral edge of the transparent plate 4, the transparent plate 4, and the detector body 1 And a turn 6 sandwiched between the two.
In this embodiment, a pointer reading device 7 that electrically converts the rotational displacement of the pointer 3 is provided in the detector.

The detector main body 1 includes a bottomed cylindrical casing 11, a pressure introducing portion (not shown) provided in the casing 11, and a rotating shaft 120 connected to the pointer 3 with pressure introduced from the pressure introducing portion. And an internal mechanism 12 for converting into rotation.
Although the illustration of the specific structure of the internal mechanism 12 is omitted, for example, a structure such as a Bourdon tube or a bellows that is displaced by the pressure introduced from the pressure introducing portion can be exemplified. The pressure introduction part has a stock provided on the outer peripheral wall of the casing 11 and a threaded part that is screwed to the installation part of the liquid storage tank, and a pressure introduction hole that communicates with the internal space of the liquid storage tank inside. A structure in which is formed can be illustrated.
The scale plate 2 is a disc having a scale 20 on its front surface, and an insertion hole 21 through which the rotating shaft 120 is inserted is provided at the center thereof. The scale 20 is a plurality of line segments whose tips are formed in the insertion holes 21, and these line segments are separated from each other by a predetermined interval. A numerical value is displayed near the scale 20.

The pointer 3 indicates the pressure as the value of the scale 20 on the scale plate 2 by making the rotation of the rotation shaft 120 a large rotational displacement, and the rotation center 30 connected to the rotation shaft 120. And a first side portion 31 and a second side portion 32 that are fixed to the rotation center portion 30 and arranged to face each other with the rotation center portion 30 interposed therebetween.
The rotation center part 30 has a disk part 30B and a shaft part 30A for connecting and fixing the rotation shaft 120 to the center part of the back surface of the disk part 30B.
The first side portion 31 is formed in a fan shape whose width dimension increases as the distance from the rotation center portion 30 increases. The second side portion 32 displays the pressure value together with the scale 20, and the width dimension decreases as the distance from the rotation center portion 30 increases. The size of the pointer width t1 at the portion of the first side portion 31 in contact with the rotation center portion 30 is set larger than the pointer width t2 at the portion of the second side portion 32 in contact with the rotation center portion 30 (see FIG. 3 and FIG. 3). (See FIG. 5).
The transparent plate 4 is a transparent disc formed from an inorganic material such as glass, or a plastic material such as acrylic or polycarbonate.

The cover 5 includes a ring-shaped portion 51 that supports the outer peripheral edge of the transparent plate 4, and a cylindrical portion 52 that is integrally formed on the outer peripheral edge of the ring-shaped portion 51 and is attached to the outer peripheral surface of the casing 11.
The turn 6 includes a ring-shaped portion 61 that sandwiches the transparent plate 4 between the cover 5 and a cylindrical portion 62 that is integrally formed with the inner peripheral edge of the ring-shaped portion 61 and engages with the inner peripheral wall of the casing 11. Have. The outer peripheral wall of the ring-shaped part 61 abuts on the inner peripheral wall of the cylindrical part 52 of the cover 5. The outer peripheral wall of the ring-shaped part 61 may be separated from the inner wall part of the cylindrical part 52 of the cover 5.

The pointer reading device 7 is provided on the front side of the rotation center portion 30 of the pointer 3 and has a magnet 71 that rotates in association with the direction of the magnetic pole with respect to the rotation of the pointer 3. Hall elements 72 as a plurality of magnetic sensors arranged adjacent to each other on a plane parallel to the three rotation planes, and an electric signal corresponding to the rotation angle of the pointer 3 by calculating a signal output from these Hall elements 72 A measurement circuit unit 73 for outputting a signal, a Hall element 72 and a measurement circuit unit 73 are provided, a replacement transparent plate 74 that can be attached to the casing 11, and a magnet fixture 75 for fixing the magnet 71 to the pointer 3. Configured.
A magnetic orientation sensor 70 is configured including the Hall element 72 and the measurement circuit unit 73.

The specific structure of the main part of the pointer reading device 7 is shown in FIGS. 3 is an exploded perspective view of the main part of the pointer reading device 7, FIG. 4 is an exploded perspective view showing the positions of the magnet fixture 75 and the magnet 71, and FIG. It is a back view which shows the state performed.
3 to FIG. 5, the magnet 71 is formed in a short cylindrical shape, and is provided at the rotation center portion 30 of the pointer 3 with a magnetic orientation with respect to the magnet fixture 75.
The magnet fixture 75 is integrally formed from a material such as plastic or aluminum, and includes a cover 75A that covers the magnet 71 and a substantially cylindrical mounting portion 75B that is provided on the cover 75A. The center part 30 can be attached and detached.

The cover 75 </ b> A has an internal space sufficient to cover the front and side portions of the magnet 71.
The attachment portion 75B includes a ring-shaped portion 75B1 whose inner peripheral portion is formed by bending outward from the lower end portion of the cover 75A, and a cylindrical portion 75B2 formed integrally with the ring-shaped portion 75B1.
The plane of the ring-shaped portion 75B1 is parallel to the plane of the cover 75A.
The attachment portion 75B includes a first fitting portion 751 fitted to the first side portion 31 of the pointer 3, a second fitting portion 752 fitted to the second side portion 32, and the first fitting portions 751. And two hooks 753 that are formed at positions away from the second fitting portion 752 and are engaged with the back surface side of the rotation center portion 30.

The first fitting portion 751 is a notch formed from the lower end of the cylindrical portion 75B2 to the ring-shaped portion 75B, and the width dimension thereof is a pointer width of a portion close to the rotation center portion 30 of the first side portion 31. Same as t1. A slit 75A1 is formed continuously from the lower end portion of the cover 75A toward the top portion of the cover 75A.
The second fitting portion 752 is a notch formed from the lower end of the cylindrical portion 75B2 to the ring-shaped portion 75B, and the width dimension thereof is a pointer width of a portion close to the rotation center portion 30 of the second side portion 32. Same as t2. Then, a slit (not shown) is formed from the lower end portion of the cover 75A toward the top portion continuously from the second fitting portion 752. Since the dimension t1 is larger than the dimension t2, the position where the magnet fixing tool 75 is fixed to the pointer 3 is uniquely determined.
The magnet 71 arranges the S pole and the N pole along the longitudinal direction of the pointer 3 so that the orientation of the SN pole of the magnet 71 with respect to the pointer 3 is determined simply by installing the magnet fixture 75 on the rotation center portion 30. Then, it is fixed to the magnet fixture 75.

The hook 753 includes a main body portion 753A formed in the same arc as the cylindrical portion 75B2, and a bent portion 753B continuously formed on the lower end side of the main body portion 753A. The bent portion 753B includes a support portion 753C that supports the back side of the rotation center portion 30 and an extension portion 753D that extends outward from the main body portion 753A. The two hooks 753 are arranged opposite to each other with the magnet 71 interposed therebetween.
An elastic member 76 that urges the magnet 71 toward the magnet fixture 75 is provided between the rotation center portion 30 of the pointer 3 and the magnet 71. The elastic member 76 is arranged to suppress the backlash of the magnet fixture 75 and is constituted by a disk-shaped leaf spring.

As shown in FIGS. 1 and 2, the replacement transparent plate 74 is a disc having substantially the same thickness and diameter as the transparent plate 4 provided in advance in the detector, is less likely to chip than glass, and has weather resistance. A transparent acrylic plate and a polycarbonate plate are used because of their properties.
Two markings 74M corresponding to the magnetic field detection orientation of the Hall element 72 are provided from the outer peripheral edge to the center of the replacement transparent plate 74. The marking 74M is used for alignment with the scale 20 disposed on both sides of the scale plate 2.

A circular opening 74A is formed at the center of the replacement transparent plate 74, and a bottomed cylindrical sensor case 77 is provided in the vicinity of the inner peripheral edge of the opening 74A. A support member 78 that supports the measurement circuit unit 73 is provided in the sensor case 77 and the opening 74 </ b> A of the replacement transparent plate 74.
The sensor case 77 has a bottom portion 771 in which a through hole 77A through which a cable 79 connected at one end to the measurement circuit portion 73 is formed, and a cylindrical portion 772 whose opening end portion is sealed on the front surface of the replacement transparent plate 74. And are integrally formed. An O-ring is used to seal the cylindrical portion 772 and the replacement transparent plate 74. An internal thread portion that is screwed into the sensor case 77 is formed on the inner peripheral portion of the opening end of the cylindrical portion 772.
The support member 78 is a cylindrical member that houses the columnar measurement circuit portion 73 therein, and a flange 78A that sandwiches the replacement transparent plate 74 with the sensor case 77 is formed on the outer periphery thereof.
The Hall element 72 is provided at the end of the measurement circuit unit 73 on the magnet 71 side, and the surface thereof is embedded by a resin mold 78B to be protected from condensation and the like.

The plurality of Hall elements 72 are arranged orthogonal to each other so that the magnetic field detection directions are different from each other. That is, when the pointer 3 is rotated, the direction of the magnetic pole is interlocked, so that a plurality of Hall elements 72 having different magnetic field detection directions are provided at positions facing the magnet 71.
The measurement circuit unit 73 has a structure in which a circuit board (not shown) is housed in a cylindrical case. The circuit board is an orientation of a magnetic field detected based on signals output from a plurality of Hall elements 72, that is, a magnet 71. A calculation unit (not shown) for calculating the magnetic orientation of the calculation unit is included, and the calculation result calculated by the calculation unit is output to the outside through the cable 79 as an electrical signal. The cable 79 is connected to a power supply device (not shown) and a device that uses an electrical signal from the pointer reading device 7.

For example, the technique described in Japanese Patent No. 4111813 can be used for the angle detection device including the Hall element 72 and the calculation unit of the measurement circuit unit 73.
When a plurality (two) of Hall elements are arranged orthogonal to each other in a predetermined plane, a magnet is placed on these Hall elements, and the magnet is rotated in a plane parallel to the plane, As shown in FIG. 6, the hall output voltage obtained is two sine waves V1 and V2 whose phases are shifted by 90 degrees. As shown in FIG. 7, the ratio of the voltage output from the Hall element to the power supply voltage continuously increases from the minimum value to the maximum value when the rotation angle of the magnet is 0 ° to 360 °, and increases to 360 °. Then, it returns to the minimum value and rises again when the rotation angle increases from 360 degrees. Since the ratio of the output voltage to the power supply voltage is largely switched when the rotation angle reaches 360 degrees, there is a possibility that a detection error will occur if the actually used magnet rotates over the position of 360 degrees. In the embodiment, the rotation range of the pointer 3 is set to 0 to 270 degrees, and the angle of this range does not cross 360 degrees in FIG. 7, for example, the zone H in FIG.

Next, a method for mounting the pointer reading device 7 of this embodiment will be described.
In order to attach the pointer reading device 7 to the detector, a magnetic azimuth sensor 70 including a Hall element 72 and a measurement circuit unit 73 is attached to a support member 78 in advance. A replacement transparent plate 74 is held.
Then, the cover 5 and the transparent plate 4 attached to the detector main body 1 of the detector are removed, and the elastic member 76 and the magnet fixture 75 are attached to the pointer 3 at the rotation center portion 30 of the pointer 3. A magnet 71 whose magnetic orientation has been previously positioned is fixed to the magnet fixture 75. Further, the replacement transparent plate 74 to which the support member 78 and the like are attached is attached to the measuring device main body 1, and the replacement transparent plate 74 is fixed to the measuring device main body 1 with the cover 5. In attaching the replacement transparent plate 74 to the measuring instrument main body 1, the marking 74 </ b> M formed in the vicinity of the outer periphery of the replacement transparent plate 74 corresponding to the magnetic field detection direction of the Hall element 72 is aligned with the scale 20 of the scale plate 2. Thus, the output signal from the measurement circuit unit 73 is a signal that matches the direction of the pointer of the detector.

In the detector to which the pointer reading device 7 is attached, when the liquid level of the stored liquid in the liquid storage tank changes, the pressure difference across the tank changes, and the change in pressure is transmitted to the detector. Then, the pointer 3 rotates together with the rotation shaft 120 of the internal mechanism 12 of the detector.
When the pointer 3 is rotated, the magnet 71 provided at the rotation center portion 30 of the pointer 3 is rotated in the rotation plane of the pointer 3, and the rotation angle is detected by the magnetic direction sensor 70. A signal detected by the magnetic azimuth sensor 70 is output to the outside through the cable 79.

Therefore, in the present embodiment, the following operational effects can be achieved.
(1) A magnet 71 that rotates in association with the orientation of the magnetic pole with respect to the rotation of the pointer 3 is provided on the front side of the rotation center 30 of the pointer 3, and the rotation surface of the pointer 3 faces the magnet 71. A plurality of Hall elements 72 having different magnetic field detection directions are arranged adjacent to each other on a plane parallel to the surface, a measurement circuit unit 73 is connected to the Hall element 72, and the Hall element 72 and the measurement circuit unit 73 are replaced with a transparent plate 74 for replacement. The pointer reading device 7 is configured by being attached to the head. And the measurement circuit part 73 was set as the structure which calculates the signal output from the Hall element 72, and outputs the electrical signal corresponding to the rotation angle of the pointer 3. Therefore, by replacing the transparent plate 4 of the detector with the replacement transparent plate 74 and attaching the magnet 71 to the pointer 3, the attaching operation of the pointer reading device 7 can be easily performed. That is, it is not necessary to replace the detector main body 1, the pointer 3, the scale plate 2, and the internal mechanism 12 installed at the site. After the pointer reading device 7 is attached to the detector, the operator reads the movement of the pointer 3 in an analog manner with the scale plate 2 and takes out as an electric signal with the magnet 71, the hall element 72 and the measurement circuit unit 73. Can do.

(2) The magnet 71 is fixed to the magnet fixture 75 with a magnetic orientation determined, and the magnet fixture 75 can be attached to and detached from the pointer 3. Then, the pointer 3 is set so that the pointer width of the first side portion 31 positioned on the rear side in the vicinity of the rotation center portion 30 is larger than the pointer width of the second side portion 32 positioned on the distal end side of the pointer. The magnet fixing tool 75 includes a first fitting portion 751 that fits the first side portion 31 and a second fitting portion 752 that fits the second side portion 32. Therefore, since the magnetic orientation of the magnet 71 is determined in advance with respect to the magnet fixture 75, the magnet 71 can be uniquely determined with respect to the direction of the pointer 3 simply by attaching the magnet fixture 75 to the pointer 3. Thus, the magnet 71 can be easily mounted.

(3) Since the marking 74M corresponding to the magnetic field detection direction of the Hall element 72 is provided in the vicinity of the outer periphery of the replacement transparent plate 74, the marking position of the replacement transparent plate 74 is set in a specific direction with respect to the scale plate 2 of the detector. The magnetic orientation sensor 70 can correctly measure the orientation of the pointer 3 with respect to the scale plate 2.

(4) By providing the elastic member 76 between the rotation center portion 30 of the pointer 3 and the magnet fixture 75 on which the magnet 71 is mounted, rattling of the magnet fixture 75 is suppressed, and the detection accuracy of the detector is improved. To do.

(5) The magnet fixture 75 includes a cover 75A that covers the magnet 71, and a hook 753 that is provided on the cover 75A and that engages with the back side of the pointer 3. Therefore, it is possible to prevent the magnet 71 from being detached from the pointer 3 by the cover 75A and to prevent the magnet fixing tool 75 itself from being accidentally detached from the pointer 3 by the hook 753, so that the detection accuracy can be increased.
(6) Since a plurality of hooks 753 are arranged so as to face each other with the magnet 71 interposed therebetween, the support to the pointer 3 is stabilized.

(7) The hook 753 includes a bent portion 753B that is continuously formed on the lower end side of the main body portion 753A, and the bent portion 753B includes a support portion 753C that supports the back side of the rotation center portion 30. The main body portion 753A includes an extending portion 753D that extends outward. Therefore, the bent portion 753B has a convex shape toward the center portion of the magnet fixture 75. Therefore, when the hook 753 is attached to and detached from the rotation center portion 30 of the pointer 3, the bent portion 753B is the center of rotation. It will be displaced smoothly with respect to the outer peripheral part of the part 30, and the mounting | wearing operation | work to the pointer | guide 3 of the magnet fixing tool 75 can be performed easily.

(8) The periphery of the opening 74A formed in the replacement transparent plate 74 is covered with a bottomed cylindrical sensor case 77, and a support member 78 is attached to the sensor case 77 and the opening 74A of the replacement transparent plate 74. The measurement circuit portion 73 is supported by the support member 78, and the sensor case 77 has a bottom portion 771 in which a through hole 77A through which a cable 79 is connected to the measurement circuit portion 73 at one end, and an opening end portion is formed. The cylindrical portion 772 sealed with the replacement transparent plate 74 is used. Therefore, since the measurement circuit unit 73 and the magnet 71 are sealed inside the replacement transparent plate 74, the internal mechanism 12 and the measurement circuit unit 73 of the detector are shielded from external dust and rainwater. Thus, the reliability of the detector and the pointer reading device 7 is prevented from being lowered.

(9) The support member 78 is configured to be screwed into the female thread portion of the cylindrical portion 772 of the sensor case 77 and to sandwich the replacement transparent plate 74 between the flange 78A formed on the outer peripheral portion and the sensor case 77. Since the measurement circuit unit 73 and the hall element 72 are supported by the support member 78, the measurement circuit unit 73 and the hall element 72, which are main components of the pointer reading device 7, are simply attached to the replacement transparent plate 74. Can do.

It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
For example, in the above-described embodiment, a pair of screw portions that are screwed to the sensor case 77 and the support member 78 are formed to sandwich the replacement transparent plate 74 between the sensor case 77 and the support member 78. The sensor case 77 may be fixed to the replacement transparent plate 74 with a plurality of screws.
Further, as the plurality of Hall elements 72 having different magnetic field detection directions, a commercially available sensor integrally molded in one package may be used.

Furthermore, in the present invention, if the fixing position of the magnet fixing tool 75 to the pointer 3 can be uniquely determined, a structure other than the above embodiment, for example, the back surface of the rotation center portion 30 is used instead of the hook 753. A structure in which the pin to be supported is penetrated to the opening end side of the magnet fixture 75 may be employed. Even if the hook 753 is employed, the number may be one.
In the above embodiment, the detector is a pressure gauge. However, in the present invention, the differential pressure gauge may be a detector. Although the Hall sensor 72 is used as the magnetic sensor, a magnetoresistive element may be used instead of the Hall element 72.
The detector of the present invention is not limited to the one installed in the liquid storage tank, and may be one installed in piping used in the plant.

  The present invention can be used for a pressure gauge, a differential pressure gauge, and other detectors.

  DESCRIPTION OF SYMBOLS 1 ... Detector main body, 2 ... Scale plate, 3 ... Pointer, 4 ... Transparent plate, 5 ... Cover, 7 ... Pointer reader, 11 ... Casing, 12 ... Internal mechanism, 30 ... Center of rotation, 31 ... First Side part 32 ... Second side part 70 ... Magnetic orientation sensor 71 ... Magnet 72 ... Hall element (magnetic sensor) 73 ... Measurement circuit part 74 ... Transparent transparent plate 74A ... Opening part 74M ... Marking 75 ... Magnet fixture, 77 ... Sensor case, 77A ... Through-hole, 78 ... Support member, 79 ... Cable

Claims (5)

A pointer reading is provided in which a scale plate is provided in the detector body, and the transparent plate covering the front of the aneroid detector having a pointer rotating on the scale plate is replaced to electrically convert the pointer rotation displacement of the detector. A device,
A magnet that is provided on the front side of the center of rotation of the pointer and rotates in association with the orientation of the magnetic pole with respect to the rotation of the pointer, and a surface that faces the magnet and is parallel to the rotation surface of the pointer A plurality of magnetic sensors arranged adjacent to each other and having different magnetic field detection directions, and a measurement circuit unit that calculates signals output from these magnetic sensors and outputs an electrical signal corresponding to the turning angle of the pointer And a replacement transparent plate which is provided with the magnetic sensor and the measurement circuit unit and which can be attached to the detector body. In the pointer reading device according to claim 1,
The magnet is fixed in a magnetic orientation with respect to a magnet fixture, the magnet fixture is detachable from the pointer, and the pointer is a first side portion located on the rear side in the vicinity of the center of rotation. The width of the pointer is set to be larger than the width of the pointer on the second side located on the tip end side of the pointer, and the magnet fixture is fitted to the first side and the second side. And a second fitting part fitted to the part, and a marking corresponding to the magnetic field detection direction of the magnetic sensor is provided in the vicinity of the outer periphery of the replacement transparent plate. In the pointer reading device according to claim 2,
A pointer reading device characterized in that an elastic member for biasing the magnet toward the magnet fixture is provided between a rotation center portion of the pointer and the magnet. In the pointer reading device according to any one of claims 1 to 3,
2. The pointer reading device according to claim 1, wherein the magnet fixture includes a cover that covers the magnet, and a hook that is provided on the cover and engages with the back side of the pointer. In the pointer reading device according to any one of claims 1 to 4,
A bottomed cylindrical sensor case that covers the peripheral edge of the opening formed in the replacement transparent plate, and a support member that is provided in the sensor case and the opening of the replacement transparent plate and supports the measurement circuit unit The sensor case includes a bottom portion in which a through hole through which a cable having one end connected to the measurement circuit portion is formed, and a cylindrical portion in which an opening end portion is sealed by the replacement transparent plate. A pointer reading device comprising:

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