JP5027191B2 - Pressure sensor and adjustment method thereof - Google Patents

Description

  The present invention relates to a pressure sensor that detects a displacement of a diaphragm that responds to the pressure of a fluid using a Hall element, and an adjustment method thereof.

When detecting the pressure of the fluid, the pressure of the fluid is guided to one side of the diaphragm, and the force of the fluid that moves the diaphragm against the spring force biased against the other side of the diaphragm is detected as pressure. To be done. There are known ones that actuate a mechanical switch by a diaphragm that is displaced by the pressure of the fluid and output a signal indicating that the pressure has reached a predetermined value, or that output an analog output signal corresponding to the displacement of the diaphragm. .
Piezoresistive (semiconductor) pressure sensors and capacitive pressure sensors are known as devices that output a signal having a magnitude corresponding to the displacement of the diaphragm, but these are expensive.
In addition, pressure sensors using Hall elements have been proposed in which a permanent magnet is attached to the diaphragm and the displacement of the diaphragm is detected using a Hall element (Patent Documents 1 to 7).

As the magnetic flux density acting on the Hall element increases, the output voltage of the Hall element increases. By detecting this output voltage, the pressure of the introduced fluid can be measured. At this time, if the magnet is displaced in a region where the displacement of the magnet with respect to the Hall element and the output voltage of the Hall element are linear, the displacement of the magnet and the output of the Hall element are in a proportional relationship, and accurate pressure detection is possible. Become.
There is a predetermined proportional relationship between the output voltage of the Hall element and the magnetic flux density, but the relationship between the position of the magnet and the output voltage of the Hall element depends on the individual variations of the Hall element and the magnet, the Hall element and the magnet. Each product will be different due to variations in distance. Even with such various variations, it is necessary to adjust the span so that each product has a constant pressure and output voltage characteristics.

The pressure sensor described in Patent Document 1 (Japanese Patent Laid-Open No. 56-86324) detects pressure based on a change in the distance between a magnet interlocked with a diaphragm and a Hall IC, and the first poles facing the same pole A permanent magnet and a second permanent magnet are provided, and a pressure operating point is set by a fine adjustment screw or a cap. Further, adjustment is possible by laser trimming the adjustment resistor.
The pressure sensor described in Patent Document 2 (Japanese Patent Application Laid-Open No. 09-170958) is a method of inserting a prescribed coil spring after selecting a spring constant necessary for span adjustment. There was a problem that the variation was large and the load scale (span) was not stable.
The pressure sensor described in Patent Document 3 (Japanese Patent Laid-Open No. 2000-18997) performs span adjustment by adjusting a variable resistor installed on a substrate, but the parts are expensive and have a drip-proof structure. For this reason, it is necessary to apply a waterproof paint, and it takes time and effort, and the resistance value of the trimmer resistor may shift during application. In addition, there is a problem that adjustment equipment for adjusting the variable resistance is expensive.
The pressure sensors described in Patent Document 4 (Japanese Patent Laid-Open No. 56-155824), Patent Document 5 (Japanese Patent Laid-Open No. 08-327483) and Patent Document 6 (Japanese Patent Laid-Open No. 2000-214036) are a pair of the same polarity. This is a structure in which a hall element is disposed in the middle and two magnets are used to adjust the magnetic flux density. Moreover, since two expensive magnets (rare earth neodymium, samarium cobalt (CoSm), etc.) are used, there is a problem in terms of cost.
Patent Document 7 (Japanese Patent Application Laid-Open No. 08-327484) describes a pressure sensor including a magnetic plate (iron plate) for the purpose of reducing temperature drift.

JP-A-56-86324 JP 09-170958 A JP 2000-18997 A JP-A-56-155824 Japanese Patent Application Laid-Open No. 08-327483 Japanese Patent Laid-Open No. 2000-214036 Japanese Patent Laid-Open No. 08-327484

As described above, in the pressure sensor using the conventional Hall element, the span (output voltage range) is adjusted within the standard with the variable resistor. Although a pressure sensor using a Hall element is relatively inexpensive, there is a problem in that an electronic component and a substrate for processing the signal of the Hall element are necessary, and the cost for circuit configuration is high.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a pressure sensor and an adjustment method thereof that can eliminate the adjustment resistor, reduce the size of the substrate, reduce the size, and simplify the adjustment process.

In order to solve the above problems, a pressure sensor of the present invention includes a joint body having an inlet for a fluid to be measured, an upper body provided with a guide chamber into which a pressure receiving plate is inserted, and the joint body and the upper body. A diaphragm having a peripheral edge sandwiched, a pressure receiving plate slidably provided in the guide chamber of the upper body on the upper surface of the diaphragm, a permanent magnet fixed to the sliding surface of the pressure receiving plate, and a guide for the upper body A linear Hall IC having a Hall element and a circuit for amplifying the output of the Hall element, disposed on the side surface of the chamber so as to face the permanent magnet, and opposite to the permanent magnet side of the linear Hall IC In addition, a magnetic plate having a gap provided so that the center position thereof coincides with the center position of the linear Hall IC is mounted.
The magnetic plate is a magnetic plate in a plate formed by laminating a plurality of resin plates and a single magnetic plate.
Furthermore, a plate selected in the adjustment step from among a plurality of plates with different positions of the laminated magnetic plates is mounted.
Still further, a magnetic plate selected in the adjusting step from among a plurality of magnetic plates having different lengths in the vertical direction of the gap is mounted.

Furthermore, the pressure sensor adjustment method of the present invention includes a joint body having an inlet for a fluid to be measured, an upper body provided with a guide chamber into which a pressure receiving plate is inserted, and the joint body and the upper body. A sandwiched diaphragm, a pressure receiving plate slidably provided in the guide chamber of the upper body on the upper surface of the diaphragm, a permanent magnet fixed to the sliding surface of the pressure receiving plate, and a guide chamber of the upper body A method for adjusting a pressure sensor having a Hall element and a linear Hall IC having a circuit for amplifying an output of the Hall element, which is installed on a side surface so as to face the permanent magnet, the permanent magnet of the linear Hall IC on the side opposite to the side, by mounting a plate and a plurality of resin plates and one of the magnetic plates are laminated, by measuring the output voltage range of the pressure sensor, the measurement result is given When not in囲内, it laminated to have the position of the magnetic plate is fitted with different other plate, or, by removing the plate, by adjusting the focusing degree of the magnetic flux passing through the linear Hall IC , and controls the output voltage range of the pressure sensor.
Furthermore, another pressure sensor adjustment method of the present invention includes a joint body having an inlet for a fluid to be measured, an upper body provided with a guide chamber into which a pressure receiving plate is inserted, and the joint body and the upper body. A diaphragm having a peripheral edge sandwiched, a pressure receiving plate slidably provided in the guide chamber of the upper body on the upper surface of the diaphragm, a permanent magnet fixed to the sliding surface of the pressure receiving plate, and a guide for the upper body A method for adjusting a pressure sensor having a Hall element and a linear Hall IC having a circuit for amplifying an output of the Hall element, which is installed on a side surface of the chamber so as to face the permanent magnet, A magnetic plate provided with a gap whose center position coincides with the center position of the linear Hall IC on the side opposite to the permanent magnet side is mounted, and the output voltage range of the pressure sensor When the measurement result is not within a predetermined range, the degree of convergence of the magnetic flux passing through the linear Hall IC is changed by changing the magnetic plate to another magnetic plate having a different gap size. It adjusts and controls the output voltage range of the pressure sensor .

According to the pressure sensor and the adjustment method of the present invention as described above, the span can be adjusted by mounting the plate for the use of only the linear Hall IC. Further, by creating a parallel magnetic field by mounting a plate with a square hole, span adjustment can be performed in a more stable state (position variation is canceled), and the accuracy of characteristics including linearity is improved.
Since the electronic circuit for adjustment such as the adjustment resistor can be eliminated and the structure can be simplified, the effects of cost reduction and size reduction can be achieved.
In addition, it is possible to realize a pressure sensor that is more excellent in environmental resistance and durability than a bare substrate product. There are also features such as a relatively easy drip-proof structure compared to a substrate with low drip-proof properties.
Furthermore, the span adjustment method is simple and does not require complicated adjustment equipment.
Furthermore, there is an effect that the total cost is reduced and the quality is stabilized by preventing the adjustment resistor from being shifted due to the waterproof coating.

It is a figure which shows the structure of 1st Embodiment of the pressure sensor of this invention, (a) is sectional drawing of the pressure sensor of this embodiment, (b) is the sectional view on the AA line of (a), (C) is a side view. It is a figure which shows an example of the plate 40 used in the 1st Embodiment of this invention. It is a figure for demonstrating the state of the pressure sensor in each state of a maximum pressurization state, a magnet displacement zero position, and an atmospheric pressure state. It is a figure for demonstrating the operating characteristic of a pressure sensor when a plate is not mounted | worn and when a different kind of plate is mounted | worn. It is a figure which shows the simulation result of magnetic flux density distribution when changing the distance between a magnet and an iron plate (SPCC). It is a figure for demonstrating concretely the span adjustment by this invention. It is a figure for demonstrating the dimension in the square hole of a plate. It is a figure for demonstrating 2nd Embodiment of the pressure sensor of this invention, and is for demonstrating the operating characteristic of a pressure sensor when a plate is not mounted | worn and when a different kind of plate is mounted | worn. FIG. It is a figure which shows the simulation result of magnetic flux density distribution when changing the magnitude | size of the space | gap formed between iron plates. It is a figure which shows the example of the plate which provided the slit-shaped space | gap. It is a figure which shows the example of the plate in which the space | gap is not provided.

FIG. 1 is a diagram showing a configuration of a first embodiment of a pressure sensor according to the present invention, where (a) is a cross-sectional view of the pressure sensor of this embodiment, and (b) is an A-A view of (a). Line sectional drawing and (c) are side views. In addition, the pressure sensor of this invention is used as a fine pressure sensor for rice cookers, for example.
In this figure, 10 is a joint body, 20 is a diaphragm, and 30 is an upper body. A joint portion 11 having an inlet for introducing a fluid to be measured is provided at the center of the bottom surface of the joint body 10, and a step portion 12 is formed on the upper surface of the joint body 10. The diaphragm 20 is made of, for example, high hardness silicone rubber. A pressure receiving plate support portion 21 is formed at the center portion, a spring force applying portion 22 formed in a donut shape around the periphery, and a flange portion 23 formed at the peripheral portion. Has been. As shown in the drawing, a protruding portion on the lower surface of the lower end flange portion 31 of the upper body 30 is fitted to the step portion 12 formed on the upper surface of the joint body 10, and the step portion 12 of the joint body 10 is The flange portion 23 of the diaphragm 20 is sandwiched and fixed by the lower end flange portion 31 of the upper body 30.

A substantially cylindrical guide chamber 32 is provided inside the upper body 30. A part of the wall surface of the guide chamber 32 is a flat portion 33, and a linear Hall IC 34 is attached to the flat portion 33. The linear Hall IC 34 is an IC in which a Hall element and an amplification circuit for amplifying the output signal of the Hall element are packaged, and outputs a signal obtained by amplifying an analog signal proportional to the magnitude of the magnetic field output from the Hall element. . An analog output signal from the linear Hall IC 34 is output from the external connection terminal 35 to the outside of the apparatus.
In the guide chamber 32 of the upper main body 30, a substantially cylindrical pressure receiving plate 24 is slidably arranged in the vertical direction in the figure. The lower end of the pressure receiving plate 24 is fixed on the pressure receiving plate supporting portion 21 of the diaphragm 20 described above. A portion of the pressure receiving plate 24 facing the flat portion 33 of the guide portion 32 is a flat portion 25, and the pressure receiving plate 24 can be moved up and down without rotating by fitting the both. A permanent magnet 26 is fixed at a position facing the linear Hall IC 34 disposed in the flat portion 33 of the guide chamber 32 of the upper body 30 of the flat portion 25 of the pressure receiving plate 24. As the permanent magnet (hereinafter simply referred to as “magnet”) 26, a magnet having a constant magnetic permeability such as Nd (neodymium) or CoSm (samarium cobalt) is used.

Further, a rectangular box-shaped plate storage portion 36 is provided outside the position where the linear Hall IC 34 is attached to the upper body 30. A plate 40 having a magnetic plate is stored in the plate storage portion 36, and the plate 40 is mounted in a recess 37 provided in the upper body 30. As a result, the plate 40 is mounted on the opposite side of the linear Hall IC 34 from the magnet 26. As will be described later, in the present invention, a plurality of types of plates are prepared, and when adjusting the pressure sensor, the most suitable type of plate for the individual is selected and stored in the plate storage unit 36, and the upper side. It is fixed to the concave portion 37 of the main body 30 by adhesion or heat welding. In some cases, the plate 40 is not attached.
The upper end surface of the pressure receiving plate 24 is pressed by a coil spring 27 supported by an adjustment screw 28 screwed into the upper portion of the upper body 30 so as to balance the spring force by the spring force applying portion 22 of the diaphragm 20. . The initial position of the magnet 26 can be adjusted with the adjusting screw 28.
The guide chamber 32 is provided with an air vent hole 38 so that the region B formed by the inside of the diaphragm 20 and the upper main body 30 is maintained at atmospheric pressure.

FIG. 2 is a diagram showing an example of a plurality of types of plates 40 used in the first embodiment of the present invention.
In the example shown in this figure, the plate 40 is formed by laminating one magnetic plate 41 having two horizontally long square holes 44 formed in the center and two resin plates 42 and 43 as shown in the figure. Structure. The magnetic plate 41 may be any material having a high magnetic permeability, but here, it is assumed that an iron plate (SPCC) is used. (Hereinafter, the magnetic plate is simply referred to as “iron plate”.) And, the first type plate (plate I) shown in FIG. The second type of plate (Plate II) shown in FIG. 2 is centered on the iron plate 41, and the third type of plate (Plate III) shown in FIG.
By inserting the plate 40 into the plate housing portion 36 and mounting it in the concave portion 37 of the upper body 30, the plate 40 is positioned so that the center position of the square hole 44 coincides with the center position of the linear Hall IC 34. Installed.
A distance between the linear Hall IC 34 and the iron plate 41 is selected by selecting any one of these three types of plates (Plate I, Plate II, Plate III) and mounting the plate on the plate storage 36. It becomes possible.

  In the pressure sensor 1 configured as described above, the joint portion 11 provided in the joint body 10 is connected to a pipe for introducing a fluid to be measured. When the fluid to be measured does not exist in the pipe, the pressure receiving plate 24 maintains a predetermined initial position against the weight of the coil spring 27 and the pressure receiving plate 24 by the spring force of the diaphragm 20 itself. . When fluid is present in the pipe and fluid is introduced into the region A, the fluid pressure acts on the lower side of the diaphragm 20 and raises the pressure receiving plate 24. As a result, the magnet 26 is also lifted, and the displacement is detected by the linear Hall IC 34 as a change in magnetic flux density, whereby the fluid pressure can be detected.

(A), (b), and (c) of FIG. 3 are sectional views showing the state of the pressure sensor in each of a maximum pressure state, a magnet displacement zero position, and an atmospheric pressure state, respectively. Is a diagram showing magnetoelectric conversion characteristics, and (e) is a diagram showing displacement output characteristics.
In the present invention, the magnet 26 is attached so that the magnetization direction is the vertical direction in the figure, and the Hall element in the linear Hall IC 34 is perpendicular to the mounting surface near the boundary between the N pole and S pole of the magnet. Only the magnetic field component is detected. The detected magnetic field is zero at the boundary between the N pole and the S pole, and in this vicinity, the magnetic flux density changes linearly with respect to the movement of the magnet, so that an output with good linearity can be obtained.

As shown in FIG. 3A, in the atmospheric pressure state (C), as described above, the spring force of the diaphragm 20 and the pressure receiving plate 24 pressed by the coil spring 27 are balanced, and the center position of the magnet 26 is The position is 0.5 mm lower than the center position of the linear Hall IC 34 (displacement amount -0.5 mm). At this time, in this pressure sensor, the magnetic flux density of the linear Hall IC 34 is −23 [mT], and the output voltage is 1.0 [V].
In the magnet displacement zero position (B) shown in FIG. 3B, the displacement amount (the center position of the magnet with respect to the center position of the linear Hall IC) is 0 mm, the magnetic flux density at that time is 0 [mT], and the output voltage Becomes 2.5 [V].
At the time of maximum pressurization (A) shown in FIG. 3C, the central portion of the diaphragm 20 and the pressure receiving plate 24 are raised so that the central position of the magnet 26 is 0.5 mm above the central position of the linear Hall IC 34. (The displacement is + 0.5mm), the magnetic flux density is 23 [mT], and the output voltage is 4.0 [V].
As a result, as shown in the magnetoelectric conversion characteristics of FIG. 3D and the displacement output characteristics of FIG. 3E, the fluid pressure is detected from the output voltage that responds to the fluid pressure using the portion with good linearity. be able to.

However, as described above, the relationship between the position of the magnet and the output voltage of the Hall element varies depending on each product due to individual variations of the Hall element and the magnet, and variations in the distance between the Hall element and the magnet. It is necessary to adjust the span so that the product has a certain pressure and output voltage characteristics.
Therefore, in the present invention, according to the characteristics of each pressure sensor, the plate most suitable for the individual is selected and mounted, or the plate is not mounted, thereby adjusting the span without using an adjustment resistor. I do.

FIG. 4 is a diagram for explaining the operating characteristics of the pressure sensor when the plate is not mounted and when different types of plates are mounted.
4 (a) is a cross-sectional view of the pressure sensor of the present invention, similar to FIG. 1 (a), and FIGS. The figure explaining the magnetic field lines passing through the linear Hall IC 34 when the plate I is mounted, when the plate II is mounted, and when the plate III is mounted, (f) is each of the cases (b) to (e) The figure which shows the magnetoelectric conversion characteristic (displacement of a magnet with respect to magnetic flux density and an output voltage characteristic) in (g) is a displacement output characteristic in each case of said (b)-(e) (the output voltage and magnetic flux density characteristic with respect to the displacement of a magnet). ).

FIG. 4B is a diagram for explaining magnetic lines of force that are emitted from the magnet 26 and pass through the linear Hall IC 34 when the plate 40 is not mounted, and in the vicinity of the plate housing portion 36 in the cross-sectional view on the left side. In this case, the lines of magnetic force emitted from the magnet 26 and passing through the linear Hall IC 34 are shown on the right side. As shown in this figure, when the plate 40 is not mounted (the distance from the plate is infinite). Equivalent to being large), it can be said that the lines of magnetic force are most spread and there is no focusing of the lines of magnetic force. In this case, the range (span) of the output voltage is reduced as compared with the case where the plate I of (c) described later is mounted.

FIG. 4C is a diagram showing a case where the plate I is mounted. The state where this plate I is attached is the reference state. As shown in the figure, in this case, the iron plate 41 in the plate 40 is mounted so as to be the farthest position from the linear Hall IC 34, and the degree of convergence of the magnetic lines of force from the magnet 26 is the same as that when another plate is mounted. It can be said that it is small in comparison.
(D) of FIG. 4 is a figure which shows the case where plate II is mounted | worn. In this case, the iron plate 41 is located at the center of the plate 40, and the iron plate 41 is attached at a position closer to the linear Hall IC 34 than in the case of the plate I in (c). In this case, the degree of convergence of the magnetic flux can be said to be medium, and the span is increased as compared with the case (c).
(E) of FIG. 4 is a figure which shows the case where plate III is mounted | worn. In this case, the iron plate 41 in the plate 40 is mounted so as to be closest to the linear Hall IC 34. As a result, the degree of convergence of the magnetic flux from the magnet 26 is maximized, that is, the magnetic flux density passing through the Hall element is greater than in other cases, and the span is maximized.

As a result of the above, in the magnetoelectric conversion characteristics of FIG. 4 (f), the gradient of the displacement of the magnet with respect to the magnetic flux density is greater when the plate is not mounted (N in the figure) than when the plate I is mounted (I in the figure). growing. In addition, when plate II is attached (II in the figure), the inclination of the change of the magnet with respect to the magnetic flux density is smaller than when plate I is attached, and when plate III is attached (III in the figure), it is further inclined. Becomes smaller.
In the displacement output characteristics of FIG. 4 (g), the slope of the output voltage with respect to the displacement of the magnet is smaller when the plate is not attached (none in the figure) than when the plate I is attached (I in the figure). Become. When plate II is attached (II in the figure), the slope of the output voltage relative to the displacement of the magnet is larger than when plate I is attached, and when plate III is attached (III in the figure), it is further inclined. Becomes larger.
In this way, based on the case where plate I is installed, the characteristic is evaluated after removing the plate or changing to plate II or plate III after evaluating the characteristic, and the required characteristic is absorbed. Can be adjusted.

FIG. 5 is a diagram showing a result of simulating the magnetic flux density distribution when the distance between the magnet and the iron plate having a gap is changed.
In this figure, (a) is a graph showing a simulation result of the relationship between the distance between the linear Hall IC 34 and the iron plate and the magnetic flux density, and (b) to (e) are the distances between the Linear Hall IC 34 and the iron plate being 3.2 mm and 3.5 mm. FIG. 4 is a diagram showing a simulation result of a magnetic flux density distribution in each case when there is no 4.2 mm and an iron plate.
As shown in this figure, as the distance between the iron plate and the linear Hall IC becomes smaller, the converged magnetic flux passes through the Linear Hall IC, and as shown in FIG. You can see that it is getting bigger. That is, the result shown in FIG.
Thus, the convergence of the magnetic flux detected by the Hall element changes according to the installation position of the iron plate provided with a gap, that is, the distance between the iron plate and the linear Hall IC, and the span can be adjusted. .

A method for adjusting a pressure sensor according to the present invention will be described.
Assume that the assembly of the pressure sensor shown in FIG. However, at this point, the reference plate I is temporarily attached to the plate storage portion 36.
In this state, the adjusting screw 28 is adjusted, and the characteristics of the pressure sensor are measured.
As a result, when the output voltage range is within the predetermined range, the plate I is fixed to the upper body 30 as it is, and the adjustment operation is finished.
On the other hand, when the output voltage range is not within the predetermined range, the plate I is removed or replaced with another plate II or plate III to measure the characteristics. As a result, when the output voltage range is within the predetermined range, the plate is fixed to the upper body 30 when the plate is attached, and when the plate is attached, the adjustment work is performed. Exit.
In this way, accuracy adjustment, that is, span adjustment can be performed without using an electronic circuit.

The span adjustment according to the present invention will be described more specifically with reference to FIG.
Assume that the accuracy required for the pressure sensor is ± 6% FS (full scale) for offset accuracy at room temperature and + 12% FS / −8% FS for sensitivity accuracy.
Factors of sensitivity error are as follows: (1) Distance between sensor (Hall element) and magnet (100% Span at 1 mm, 5% FS when shifted 50 μm), (2) Magnetic flux density variation (permeability, magnet size) ) ± 3% FS, (3) spring load (+ 4% FS / −2% FS), (4) sensor sensitivity (sensor ability ± 5% FS), and the like.
The maximum total error is 5% + 3 + 4 + 5 = 17%, and 5 + 3 + 2 + 5 = −15%. In this example, the sensitivity accuracy requirement is allowed up to +12% /-8%, so if there is an adjustment range of +5% /-7%, it is theoretically possible to enter the required accuracy.
Since the control of sensitivity by inserting an iron plate as in the present invention is limited to about + 10%, the design target value is set to a point that is lowered by -5%, and when the actual measurement value is insufficient than the target value, It becomes possible to adjust the sensitivity within an allowable range by inserting.
That is, as shown in FIG. 6, when the tolerance is exceeded, the accuracy within the tolerance can be achieved by performing compensation using the mechanical method according to the present invention.

  In the above description, the case of preparing three types of plates, Plate I to Plate III, and adjusting the span depending on whether one of the plates is attached or not attached is described. There is no limitation, and the type of plate to be prepared is arbitrary. For example, only one type of plate may be prepared, the characteristics may be measured without (or attached) the plate, and the plate may be attached (or removed) according to the result.

Here, the dimensions of the square hole 44 will be described with reference to FIG.
7A is an upper cross-sectional view of the pressure sensor of the present invention, similar to FIG. 1B described above, and FIG. 7B is an enlarged view of the magnet 26 and the plate 40.
Assuming that the horizontal dimension of the magnet 26 is A and the horizontal dimension of the square hole 40 is X, the horizontal dimension X of the square hole 40 is the magnet width from the left and right ends of the magnet 26 so as not to disturb the magnetic field in the lateral direction. (A) It is desirable to have the above, that is, X ≧ A + (2A). For example, when the magnet width (A) is 2 mm, the lateral dimension (X) of the square hole 40 may be 6 mm or more.

7C is a cross-sectional view of the pressure sensor of the present invention, similar to FIG. 1A described above, and FIG. 7D is an enlarged view of the magnet 26 and the plate 40.
When the vertical dimension of the magnet 26 is B and the vertical dimension of the square hole 44 is Y, the vertical dimension Y of the square hole 44 is not particularly specified, but as a guide, the stroke amount of the magnet 26 (example shown in FIG. 2) In this case, it is desirable to have a dimension of about 1 mm), and on the other hand, it is desirable to keep the dimension to less than half of the longitudinal dimension (B) of the magnet 26. From the above, when the vertical dimension (B) of the magnet 26 is 4 mm, the vertical dimension (Y) of the square hole 44 may be about 1 mm to 2 mm.

Next, a second embodiment of the pressure sensor of the present invention will be described.
In the first embodiment of the present invention described above, span adjustment is performed by selecting one of different types of plates I to III so that the distance between the linear Hall IC 34 and the iron plate (SPCC) 41 is different. In this embodiment, a plate selected from a plurality of types of plates having different dimensions in the vertical direction (the same direction as the magnetizing direction of the magnet 26) of the provided square hole 44 is mounted. Thus, the span adjustment is performed as in the case of the first embodiment.

  FIG. 8 is a diagram for explaining a second embodiment of the present invention, in which (a) is a cross-sectional view of the pressure sensor, similar to (a) of FIG. 1, (b), (c), ( d) and (e), respectively, describe magnetic lines of force that pass through the linear Hall IC 34 when the plate 40 is not mounted, when the plate I is mounted, when the plate II is mounted, and when the plate III is mounted. (F) is a diagram showing magnetoelectric conversion characteristics (magnet displacement and output voltage characteristics with respect to magnetic flux density) in each of the cases (b) to (e), and (g) is a graph of (b) to (e). It is a figure which shows the displacement output characteristic (The output voltage with respect to the displacement of a magnet, and a magnetic flux density characteristic) in each case.

In this embodiment, as shown in FIGS. 4C to 4E, the vertical dimension (size of the gap) of the square hole 44 formed in the iron plate (SPCC) 41 of the plate 40 is as follows. Three different types of plates 40 (Plate I, Plate II and Plate III) are used. The distance between the iron plate 41 and the linear Hall IC 34 in each plate is constant.
Then, when the size of the gap of the plate I is a, the size of the gap of the plate II is b, and the size of the gap of the plate III is c, c <b <a. The plate I with the largest gap is taken as the reference plate.
As shown in the figure, the smaller the gap between the plates, the higher the degree of convergence of the magnetic flux passing through the linear Hall IC 34. As a result, as shown in FIGS. 4F and 4G, the span (output voltage range) increases as the gap between the plates decreases. Further, when the plate 40 of (b) is not mounted, the degree of focusing of the magnetic flux becomes small and the span becomes small.

FIG. 9 is a diagram illustrating a result of simulating the magnetic flux density distribution when the size of the gap (gap) formed between the iron plates is changed.
In this figure, (a) is a graph showing a simulation result of the relationship of magnetic flux density to displacement of the magnet when the gap is 0.1 mm, 0.4 mm, and 1.0 mm and when the iron plate (SPCC) is not mounted, (b (E)-(e) is a figure which shows the simulation result of magnetic flux density distribution in case the magnitude | size of the clearance gap between iron plates is 1.0 mm, 0.4 mm, 0.1 mm, and a corner without an iron plate.
As shown in this figure, the smaller the gap is, the higher the magnetic flux is focused. That is, the magnetic flux is focused in the order of (e), (b), (c), and (d). You can see that it is getting higher.

  In this way, by mounting a plate selected from one or a plurality of plates having different lengths (gap sizes) in the vertical direction of the square holes 44 formed in the plate, or by not mounting the plate, As in the case of the first embodiment described above, span adjustment can be performed.

  In FIG. 8, the position of the iron plate on the plates having different lengths in the vertical direction of the square holes is fixed, but the position of the iron plate may be changed as in the case of FIG. 4. For example, the plate III in FIG. 8E may be mounted so that the position of the iron plate is closest to the linear Hall IC 34 as shown in FIG. As a result, finer adjustments can be made.

In each of the above-described embodiments, the square holes 44 are formed in the plate 40. However, the present invention is not limited to this.
For example, a slit-shaped gap may be provided instead of the square hole 44.
FIG. 10A is a diagram showing a plate in which square holes 44 are formed as described above, and FIG. 10B is a diagram showing a configuration example of a plate in which slit-like gaps are formed instead of square holes. As shown in (b), the above-described various plates may be configured by using two long plates arranged with a gap Y therebetween.
Alternatively, instead of the square holes 44, holes having other shapes such as an ellipse may be formed.
Furthermore, you may make it provide the iron plate provided with the part of the medium whose magnetic permeability is close to 1 instead of a hole or a space | gap.

Furthermore, in the above-described embodiment, a plate including an iron plate having a square hole or a gap is used, but a square hole or a gap may not be provided.
FIG. 11 is a view showing an example of a plate in this embodiment. In the plate I shown in FIG. 11A, an iron plate 41 is arranged on the rightmost side in the drawing, and the plate storage in this direction is shown in FIG. When mounted on the portion 36, the distance from the linear Hall IC 34 to the iron plate 41 is farthest compared to other plates. In the plate II shown in (b), the iron plate 41 is arranged at the center, and the distance from the linear Hall IC 34 to the iron plate 41 is an intermediate value. The plate III shown in (c) is such that the iron plate 41 is arranged on the leftmost side in the drawing, and when mounted on the plate storage portion 36 in this direction, the distance from the linear Hall IC 34 to the iron plate 41 is different from other plates. Compared to be closest.
When the distance between the linear Hall IC 34 and the iron plate 41 is different, the degree of convergence of the magnetic flux density from the magnet is different. Therefore, either of the plates shown in (a) to (c) is selected and mounted or By not mounting the plate, the range of the output voltage from the linear Hall IC can be changed, and the span adjustment can be performed as in the above-described embodiment. However, in this case, the amount of adjustment is smaller than when the square hole 44 is formed.

  In the above-described embodiment, the description has been given by taking as an example a plate in which two resin plates 42 and 43 and one iron plate 41 are stacked. However, the present invention is not limited to this, and three or more resins are used. You may make it use the plate of the structure which laminated | stacked the board and the one iron plate 41. FIG. As a result, the span can be adjusted more finely.

  10: Joint body, 11: Joint part, 12: Step part, 20: Diaphragm, 21: Pressure receiving plate support part, 22: Spring force applying part, 23: Flange part, 24: Pressure receiving plate, 25: Flat part, 26: Permanent magnet, 27: coil spring, 28: adjustment screw, 30: upper body, 31: flange part, 32: guide chamber, 33: flat part, 34: linear Hall IC, 35: external connection terminal, 36: plate storage part, 37: recessed portion, 40: plate, 41: magnetic plate (iron plate), 42, 43: resin plate, 44: square hole

Claims (6)

A joint body having an inlet for a fluid to be measured;
An upper body provided with a guide chamber into which the pressure receiving plate is inserted;
A diaphragm having a periphery sandwiched between the joint body and the upper body;
A pressure receiving plate slidably provided in the guide chamber of the upper body on the upper surface of the diaphragm;
A permanent magnet fixed to the sliding surface of the pressure plate, and
A linear Hall IC having a Hall element and a circuit for amplifying the output of the Hall element, installed on the side surface of the guide chamber of the upper body so as to face the permanent magnet;
On the opposite side of the linear Hall IC from the permanent magnet side, a magnetic plate having a gap provided so that the center position thereof coincides with the center position of the linear Hall IC is mounted. Pressure sensor.   The pressure sensor according to claim 1, wherein the magnetic plate is a magnetic plate in a plate formed by laminating a plurality of resin plates and a single magnetic plate.   The pressure sensor according to claim 2, wherein a plate selected in the adjustment step is mounted from a plurality of plates having different positions of the laminated magnetic plates.   2. The pressure sensor according to claim 1, wherein a magnetic plate selected in the adjusting step from a plurality of magnetic plates having different lengths in the vertical direction of the gap is mounted. A joint body having an inlet for a fluid to be measured, an upper body provided with a guide chamber into which a pressure receiving plate is inserted, a diaphragm sandwiched at the periphery by the joint body and the upper body, and the upper body on the upper surface of the diaphragm A pressure receiving plate slidably provided in the guide chamber, a permanent magnet fixed to the sliding surface of the pressure receiving plate, and a side surface of the guide chamber of the upper body so as to face the permanent magnet. A method of adjusting a pressure sensor having a linear Hall IC having a Hall element and a circuit for amplifying the output of the Hall element,
The opposite side to the permanent magnet side of the linear Hall IC, by mounting the plate to a plurality of resin plates and one of the magnetic plates are laminated, by measuring the output voltage range of the pressure sensor,
When the measurement result is not within a predetermined range, the magnetic flux passing through the linear Hall IC can be obtained by attaching another plate having a different position where the magnetic plates are stacked or by removing the plate. by adjusting the focusing degree adjusting method of the pressure sensor and controlling the output voltage range of the pressure sensor. A joint body having an inlet for a fluid to be measured, an upper body provided with a guide chamber into which a pressure receiving plate is inserted, a diaphragm sandwiched at the periphery by the joint body and the upper body, and the upper body on the upper surface of the diaphragm A pressure receiving plate slidably provided in the guide chamber, a permanent magnet fixed to the sliding surface of the pressure receiving plate, and a side surface of the guide chamber of the upper body so as to face the permanent magnet. A method of adjusting a pressure sensor having a linear Hall IC having a Hall element and a circuit for amplifying the output of the Hall element,
On the opposite side of the linear Hall IC from the permanent magnet side, a magnetic plate having a gap whose center position coincides with the center position of the linear Hall IC is attached, and the output voltage range of the pressure sensor is reduced. Measure and
When the measurement result is not within a predetermined range, the convergence of the magnetic flux passing through the linear Hall IC is adjusted by changing the magnetic plate to another magnetic plate having a different size of the gap. A method for adjusting a pressure sensor , wherein an output voltage range of the pressure sensor is controlled .

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