CN211927164U - Pressure sensor having corrosion-resistant magnet - Google Patents
Pressure sensor having corrosion-resistant magnet Download PDFInfo
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- CN211927164U CN211927164U CN202020989092.1U CN202020989092U CN211927164U CN 211927164 U CN211927164 U CN 211927164U CN 202020989092 U CN202020989092 U CN 202020989092U CN 211927164 U CN211927164 U CN 211927164U
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- pressure
- receiving plate
- accommodating chamber
- metal plating
- plating film
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- 238000005260 corrosion Methods 0.000 title claims abstract description 29
- 230000007797 corrosion Effects 0.000 title claims abstract description 29
- 238000007747 plating Methods 0.000 claims abstract description 32
- 238000000576 coating method Methods 0.000 claims abstract description 24
- 239000011248 coating agent Substances 0.000 claims abstract description 23
- 239000000463 material Substances 0.000 claims abstract description 23
- 229920005989 resin Polymers 0.000 claims abstract description 22
- 239000011347 resin Substances 0.000 claims abstract description 22
- 238000004891 communication Methods 0.000 claims abstract description 21
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 claims abstract description 16
- 229910000037 hydrogen sulfide Inorganic materials 0.000 claims abstract description 16
- 229910052751 metal Inorganic materials 0.000 claims abstract description 16
- 239000002184 metal Substances 0.000 claims abstract description 16
- 238000006073 displacement reaction Methods 0.000 claims abstract description 11
- 230000004907 flux Effects 0.000 claims abstract description 5
- 229910052761 rare earth metal Inorganic materials 0.000 claims abstract description 4
- 150000002910 rare earth metals Chemical class 0.000 claims abstract description 4
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 10
- 239000003822 epoxy resin Substances 0.000 claims description 10
- 229920000647 polyepoxide Polymers 0.000 claims description 10
- 229910052725 zinc Inorganic materials 0.000 claims description 10
- 239000011701 zinc Substances 0.000 claims description 10
- 239000010408 film Substances 0.000 description 31
- 239000010410 layer Substances 0.000 description 17
- 241000209094 Oryza Species 0.000 description 13
- 235000007164 Oryza sativa Nutrition 0.000 description 13
- 235000009566 rice Nutrition 0.000 description 13
- 238000010411 cooking Methods 0.000 description 10
- 239000011247 coating layer Substances 0.000 description 8
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 6
- 238000001514 detection method Methods 0.000 description 5
- 238000000034 method Methods 0.000 description 5
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 4
- 229920006015 heat resistant resin Polymers 0.000 description 4
- 239000012530 fluid Substances 0.000 description 3
- 229910052742 iron Inorganic materials 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- 229910052779 Neodymium Inorganic materials 0.000 description 2
- 229910019142 PO4 Inorganic materials 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 238000013459 approach Methods 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- QEFYFXOXNSNQGX-UHFFFAOYSA-N neodymium atom Chemical compound [Nd] QEFYFXOXNSNQGX-UHFFFAOYSA-N 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 230000002093 peripheral effect Effects 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 2
- 239000010452 phosphate Substances 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 239000010409 thin film Substances 0.000 description 2
- 229910000838 Al alloy Inorganic materials 0.000 description 1
- 229910009369 Zn Mg Inorganic materials 0.000 description 1
- 229910007573 Zn-Mg Inorganic materials 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 229910000828 alnico Inorganic materials 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- KPLQYGBQNPPQGA-UHFFFAOYSA-N cobalt samarium Chemical compound [Co].[Sm] KPLQYGBQNPPQGA-UHFFFAOYSA-N 0.000 description 1
- 238000005238 degreasing Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000009501 film coating Methods 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 238000005304 joining Methods 0.000 description 1
- 230000005415 magnetization Effects 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 238000005554 pickling Methods 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 229910000938 samarium–cobalt magnet Inorganic materials 0.000 description 1
- 229920002379 silicone rubber Polymers 0.000 description 1
- 239000004945 silicone rubber Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Images
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- Measuring Fluid Pressure (AREA)
- Cookers (AREA)
Abstract
The utility model provides a pressure sensor who possesses magnet that has corrosion resistance. The pressure sensor includes: a lower case having a pressure chamber communicating with a communication path for supplying a pressure to be detected; an upper housing having a pressure receiving plate accommodating chamber in the base portion and having a pressure receiving plate displacement detecting portion for detecting displacement; a diaphragm which can be elastically displaced and has a fitting portion fitted to the lower end portion of the pressure receiving plate, and which separates the pressure chamber from the pressure receiving plate accommodating chamber; and a biasing member disposed in the pressure-receiving-plate accommodating chamber and biasing the diaphragm in a direction in which an inner volume of the pressure-receiving-plate accommodating chamber increases, wherein the pressure-receiving-plate displacement detecting unit includes a magnetic sensor and detects a magnetic flux density of the rare-earth permanent magnet, and the permanent magnet includes: the metal plating film is formed on the surface of the base material and has corrosion resistance to hydrogen sulfide, and the resin coating film covers the entire metal plating film and has a film thickness larger than that of the metal plating film.
Description
Technical Field
The utility model relates to a pressure sensor who possesses magnet that has corrosion resistance.
Background
As for an electric rice cooker, for example, as shown in patent document 1, there are proposed: the cooking device includes a main body having a cooking chamber, and a vacuum device, a positive pressure device, and a pressure detection module (pressure sensor) provided in a lid body, wherein the vacuum device and the positive pressure device are controlled to operate based on a detection signal from the pressure detection module (pressure sensor), thereby controlling the pressure in the cooking chamber. In such pressure control, the vacuum apparatus is operated to evacuate to a high vacuum degree of pressure not higher than atmospheric pressure (101.33kPa) in the suction stage during cooking, and to a low vacuum degree in the cooking stage, so that the pressure in the cooking chamber is maintained at a negative pressure.
As disclosed in patent documents 2 and 3, for example, it is known that a small amount of hydrogen sulfide or ammonia components, which are one cause of an odor that hinders the aroma of rice, are generated in an electric rice cooker during cooking.
Among the above pressure sensors, as a micro pressure sensor for an electric rice cooker, the following micro pressure sensors are provided in practical use: which supplies an output signal indicating a fluid pressure by detecting a displacement of a diaphragm that is displaced according to the fluid pressure using a magnetic sensor composed of a permanent magnet and a hall element. The surface of the base material of such a permanent magnet may be subjected to nickel plating.
Documents of the prior art
Patent document
Patent document 1: japanese patent laid-open publication No. 2019-10495
Patent document 2: japanese examined patent publication No. 46-24062
Patent document 3: japanese laid-open patent publication No. 9-56343
SUMMERY OF THE UTILITY MODEL
Problem to be solved by utility model
In the rice cooker, when the pressure sensor including the magnetic sensor composed of the permanent magnet and the hall element is used to repeatedly cook rice, the permanent magnet subjected to the nickel plating treatment may be corroded by the hydrogen sulfide component. This may reduce the magnetic force of the permanent magnet, which may reduce the detection accuracy (magnetic force detection capability) of the pressure sensor. Therefore, it is desired to improve the corrosion resistance of the permanent magnet to hydrogen sulfide components.
In view of the above, an object of the present invention is to provide a method for manufacturing a corrosion-resistant magnet having a corrosion-resistant magnet with which corrosion of a magnet by hydrogen sulfide components can be avoided and the corrosion resistance of the magnet can be improved, and a pressure sensor having a corrosion-resistant magnet.
Means for solving the problems
In order to achieve the above object, the present invention relates to:
(1) a pressure sensor having a corrosion-resistant magnet, comprising:
a lower case having a pressure chamber communicating with a communication path for supplying a pressure to be detected;
an upper case having a pressure-receiving-plate accommodating chamber in which a pressure-receiving plate is movably disposed in a base portion joined around a pressure chamber of the lower case, and having a pressure-receiving-plate displacement detecting portion that detects displacement of the pressure-receiving plate in accordance with the detected pressure;
a diaphragm that is elastically displaceable, has a fitting portion that is fitted to a lower end portion of the pressure receiving plate that is displaced in accordance with a pressure of the pressure chamber, and separates the pressure chamber from the pressure receiving plate accommodating chamber; and
a biasing member that is disposed in the pressure-receiving plate accommodating chamber and biases the diaphragm in a direction in which an internal volume of the pressure-receiving plate accommodating chamber increases,
the pressure receiving plate displacement detecting unit includes a magnetic sensor for detecting a magnetic flux density of the rare-earth permanent magnet held by the pressure receiving plate,
the permanent magnet has: the metal plating film is formed on the surface of the base material and has corrosion resistance to hydrogen sulfide, and the resin coating film covers the entire metal plating film and has a film thickness larger than that of the metal plating film.
(2) The pressure sensor according to (1),
the metal plating film is a zinc plating film.
(3) The pressure sensor according to (1),
the resin coating film is an epoxy resin coating film.
Effect of the utility model
According to the pressure sensor having a corrosion-resistant magnet of the present invention, since the permanent magnet has the metal plating film formed on the surface of the base material and having corrosion resistance to the hydrogen sulfide component, and the resin coating film covering the entire metal plating film and having a film thickness larger than the film thickness of the metal plating film, corrosion of the hydrogen sulfide component to the magnet can be avoided, and corrosion resistance of the magnet can be improved.
Drawings
Fig. 1 is a diagram showing steps of a method for manufacturing a corrosion-resistant magnet according to the present invention.
Fig. 2 is a sectional view showing a structure of an example of a pressure sensor including a corrosion-resistant magnet according to the present invention.
Fig. 3 is a perspective view showing an example of a corrosion-resistant magnet according to the present invention, together with a partial cross section.
Description of the symbols
10: lower case, 10A: pressure chamber, 10 IN: communication pipe, 12: upper case, 16: communication path, 18: diaphragm, 24: pressure receiving plate, 26: permanent magnet, 26F: zinc coating, 26C: resin coating layer.
Detailed Description
Fig. 2 schematically shows a configuration of an example of a pressure sensor including a corrosion-resistant magnet according to the present invention.
The pressure sensor shown in fig. 2 is disposed in a cover of an electric cooker, for example, not shown. In fig. 2, the pressure sensor includes, as main components: an upper case 12 disposed in the lid body; a lower casing 10 having a communication pipe 10IN protruding toward an opening of a pot (not shown) IN the rice cooker main body and communicating with the pot; a pressure receiving plate 24 disposed to be movable in the pressure receiving plate accommodating chamber 12A of the upper case 12; a diaphragm 18 for lifting the pressure receiving plate 24 according to the pressure IN the cooker (i.e., the detected pressure introduced through the communication tube 10IN coupled to the pressure receiving plate 24); a coil spring 22 as an urging member that urges the pressure receiving plate 24 and the diaphragm 18 IN the direction IN which the volume of the pressure receiving plate accommodating chamber 12A increases, that is, IN the direction IN which the diaphragm 18 approaches the communication tube 10 IN; a permanent magnet 26 pressed into the magnet mounting hole of the pressure receiving plate 24; and a signal processing circuit board 28 with a connector including a hall element, which is disposed on the upper case 12 so as to face the permanent magnet 26.
The upper case 12 is molded from, for example, a heat-resistant resin material (ABS). The upper case 12 is composed of a base portion welded to the joint surface of the lower case 10, and a cylindrical portion connected to the base portion and extending upward, supporting a signal processing circuit substrate 28 with a connector.
A pressure receiving plate accommodating chamber 12A partitioned by the diaphragm 18 is formed in the lower portion of the cylindrical portion. An internal thread portion 12FMS for screwing the external thread portion 14MS of the adjusting bolt member 14 is formed on the inner peripheral portion of the upper portion of the cylindrical portion, and the adjusting bolt member 14 adjusts the biasing force of the coil spring 22. A signal processing circuit board 28 with a connector is disposed at the right end of the cylindrical portion. The signal processing circuit board with connector 28 as the pressure receiving plate displacement detecting portion includes a magnetic sensor (hall element) for detecting the magnetic flux density of the permanent magnet 26 supported by the pressure receiving plate 24. The pressure receiving plate accommodating chamber 12A communicates with the inside of the lid of the rice cooker through an air through hole not shown.
On the joining surface of the base portion with the lower case 10, for example, an arc-shaped protrusion 12P that fits into the grooves 10Ga and 10Gb of the lower case 10 is formed at the ultrasonic-welded portion. A groove 12G for inserting a flange 18B of the diaphragm 18, which will be described later, is formed around the pressure receiving plate accommodating chamber 12A adjacent to the projection 12P.
The diaphragm 18 is formed of, for example, silicone rubber having a predetermined thickness (for example, a thickness of 0.3mm to 0.5 mm), and includes: a flange portion 18B inserted into the outer edge of a groove 12G formed in the base portion, a circular plate portion 18Fa abutting against the end face of a hollow conical portion 24CY at the lowermost end of a pressure receiving plate 24 described later, a tapered surface portion 18Fb integrally formed with the circular plate portion 18Fa and fitted to the side face of the conical portion 24CY, an annular portion 18Fc abutting against an extending portion 24B adjacent to the conical portion 24CY of the pressure receiving plate 24, and a movable portion 18M elastically displaceable by connecting the annular portion 18Fc to the flange portion 18B. The tapered surface portion 18Fb of the diaphragm 18 forming a part of the concave portion has a taper corresponding to the taper α of the hollow conical land portion 24CY of the pressure receiving plate 24 to be fitted, for example, 5 °. That is, the fitting portion of the diaphragm 18 is formed by the tapered surface portion 18Fb and the circular plate portion 18Fa of the diaphragm 18.
The pressure receiving plate 24 is molded from, for example, a heat-resistant resin material (ABS), and has a magnet mounting hole for press-fitting the permanent magnet 26 at a position facing the connector-equipped signal processing circuit board 28. The permanent magnet 26 is formed in a thin plate shape from a rare earth magnet, for example, any one of neodymium, samarium cobalt, and alnico. As shown in exaggerated enlargement in fig. 3, the permanent magnet 26 is formed to be 5mm square, for example, with a thickness of 2 mm. As described later, the permanent magnet 26 is formed by applying a metal plating treatment (for example, a zinc plating treatment) or a phosphate treatment to the surface of the base material and then coating a resin on the metal plating film or the phosphate film. The resin coating film is, for example, a resin coating film formed of an epoxy resin. The resin coating film formed of the epoxy resin is excellent in corrosion resistance against a trace amount of hydrogen sulfide component. Thus, as shown in fig. 3, during the galvanization, a galvanized layer 26F having a film thickness in a range of about 5 μm to about 30 μm is formed on the entire surface of the base material of the permanent magnet 26, and a resin coating layer 26C made of epoxy resin having a thickness of about 36 μm ± 4 μm is formed on the entire surface of the galvanized layer 26F. The main reason why the resin coating layer 26C is formed of an epoxy resin is to improve corrosion resistance against hydrogen sulfide and to pay attention to the following points: (1) high bonding performance with the permanent magnet 26, (2) high resistance to high temperature and humidity (resistance necessary to solve inevitable problems when used in electric cookers), and (3) thin-film coating of a coating film (epoxy resin can form a uniform thin film among various coating resins).
The reason 1 for setting the thickness of the resin coating layer 26C to a value in the range of 32 μm to 40 μm is that the galvanized layer 26F and the resin coating layer 26C are less likely to be peeled off by press-fitting because the permanent magnet 26 is press-fitted into the magnet mounting hole. The reason 2 is that when the film thickness is larger than 40 μm, the coating film becomes uneven, and the coating film may be particularly concentrated on the ridge portion (corner portion of the magnet). The reason why 3 is that a coating having a predetermined strength (peel strength, scratch strength) cannot be obtained when the thickness is small, i.e., less than 32 μm.
Therefore, as will be described later, when a trace amount of hydrogen sulfide is generated in the pot in the rice cooker main body during cooking, even if the trace amount of hydrogen sulfide intrudes into the pressure receiving plate accommodating chamber 12A through the pressure chamber 10A, the galvanized layer 26F of the permanent magnet 26 having the galvanized layer 26F and the resin coating layer 26C is more excellent in corrosion resistance against hydrogen sulfide than the nickel-plated film, and the galvanized layer 26F is coated with the resin coating layer 26C (i.e., the epoxy resin coating film protecting the galvanized layer 26F), so that corrosion of the magnet by the trace amount of hydrogen sulfide can be avoided. The pressure receiving plate 24 molded from a heat-resistant resin material (ABS) is excellent in corrosion resistance against the trace hydrogen sulfide component.
A spring receiving portion connected to one end of the coil spring 22 is formed at an upper end portion of the pressure receiving plate 24 with respect to the magnet mounting hole. The other end of the coil spring 22 is received in an annular groove in the jack bolt member 14. A protruding portion 24B that abuts the annular portion 18Fc of the diaphragm 18 is formed below the pressure receiving plate 24 with respect to the magnet mounting hole, and a hollow truncated cone portion 24CY is formed at the lowermost end. Thus, the pressure receiving plate 24 is supported by the one end of the coil spring 22 and the tapered surface portion 18Fb of the diaphragm 18, and is slidably guided to the inner peripheral surface of the upper case 12 forming the pressure receiving plate accommodating chamber 12A.
The taper angle α of the hollow tapered land portion 24CY is set to an angle in the range of, for example, 3 ° to 5 °. Thus, the diameter of the tapered frustum portion 24CY increases as it approaches the communication pipe 10IN of the lower housing 10.
Therefore, when the conical surface portion 18Fb of the diaphragm 18 receives a force in a direction of separating and pulling away from the conical frustum portion 24CY of the pressure receiving plate 24 due to the negative pressure in the pan, the reaction force of the diaphragm 18 itself acts against the force of expanding the conical surface portion 18Fb of the diaphragm 18, and thus the separation of the diaphragm 18 from the pressure receiving plate 24 can be surely avoided. That is, the means for avoiding the separation of the fitting portion is formed by the hollow conical land portion 24CY, the conical surface portion 18Fb of the diaphragm 18, and the circular plate portion 18 Fa.
The lower case 10 is molded from, for example, a heat-resistant resin material (ABS). As shown in fig. 2, the lower case 10 is configured to include: plate-shaped portion 10B for welding the joint surface of the base portion of upper case 12, attachment portions 10F integrally formed at both ends of plate-shaped portion 10B IN an opposed manner, and communication pipe 10IN joined to outer surface 10R opposed to the joint surface of plate-shaped portion 10B are formed. The communication pipe 10IN protrudes toward an opening of a pot (not shown) IN the rice cooker main body and communicates with the pot. Each mounting portion 10F has a mounting hole 10a for inserting a fastening member for mounting the pressure sensor to the lid LB of the rice cooker.
Arc-shaped grooves 10Ga and 10Gb are formed adjacent to each other in a portion of the joint surface that is joined to one end of each mounting portion 10F. A pressure chamber 10A communicating with the communication passage 16 IN the communication pipe 10IN is formed IN the central portion between the grooves 10Ga and 10 Gb. The pressure chamber 10A is surrounded by the diaphragm 18 and the tapered surface portion 10IT having one end open to the joint surface. The tapered surface portion 10IT has a taper of about 30 ° to 45 °, for example. At the end of the tapered surface portion 10IT having the smallest diameter, a stepped portion 10S having a predetermined depth Dp is formed facing the circular plate portion 18Fa of the diaphragm 18. The inner diameter of the stepped portion 10S is set to be slightly larger than the diameter of the circular plate portion 18Fa of the diaphragm 18. Thereby, a small space having the tapered surface portion 10IT is formed inside the lower case 10. Since the inner volume of the small space in the lower case 10 is small, the height of the lower end surface of the plate-like portion 10B of the lower case 10 to the uppermost end surface of the upper case 12 is lower than that in the related art. As a result, the pressure sensor can be made thinner (lower in height).
On the inner side of communication pipe 10IN, a rib 16D equally dividing communication path 16 into two is integrally formed. One end surface of the rib 16D as the termination portion is located on a common plane with the surface of the stepped portion 10S, that is, on the same plane as the surface of the stepped portion 10S. The other end surface of the rib 16D extends until it coincides with the lower end surface of the communication pipe 10 IN. By providing rib 16D IN this manner, it becomes difficult to insert a rod-like cooking utensil or the like from the opening at the lower end of communication pipe 10IN, and thus membrane 18 and pressure receiving plate 24 can be prevented from being undesirably damaged.
IN such a configuration, when the pressure IN the cooker inside the rice cooker main body rises and the pressure IN the pressure chamber 10A reaches a positive pressure equal to or higher than the atmospheric pressure via the communication path 16 of the communication pipe 10IN, the pressure receiving plate 24 and the diaphragm 18 rise, and the relative position of the permanent magnet 26 with respect to the hall element of the signal processing circuit board with connector 28 changes, so that an output signal indicating the positive pressure is sent from the signal processing circuit board with connector 28. On the other hand, when the pressure IN the cooker body drops and the pressure IN the pressure chamber 10A reaches a negative pressure equal to or lower than the atmospheric pressure through the communication path 16 of the communication pipe 10IN, the pressure receiving plate 24 and the diaphragm 18 drop, and the relative position of the permanent magnet 26 with respect to the hall element of the signal processing circuit board with connector 28 changes, so that an output signal indicating the negative pressure is sent from the signal processing circuit board with connector 28.
As an example of the method of manufacturing a corrosion-resistant magnet according to the present invention, as shown in fig. 1, for example, a base material (plating bare material) (bare material having a thickness of 2mm or 5mm square) of the magnet made of neodymium described above is prepared, and plating treatment S1 is performed on the entire surface of the base material. In the plating treatment S1, for example, the surface of the base material (plating blank) is degreased, and then the degreasing solution adhered thereto is washed with water and acid. Thereby, the iron base of the base material is exposed. Next, the deposited pickling solution is washed with water, and then flux coating treatment is performed to promote the alloying reaction between iron and zinc, followed by drying. The base material thus treated is immersed in a zinc bath under predetermined plating conditions. Thereby, a galvanized layer is formed on the entire surface of the base material in a film thickness ranging from about 5 μm to about 30 μm. The zinc-plated layer may be any plating layer containing zinc as a main component, and may be a Zn-plated layer, a Zn-AL alloy plating layer, a Zn-Mg alloy plating layer, or the like.
Finally, the base material on which the zinc plating layer is formed is cooled with warm water in order to suppress the growth of the alloy layer of iron and zinc. Thereby, the plating process S1 is completed. Next, the base material on which the galvanized layer is formed is subjected to resin coating processing S2. The resin coating process S2 is performed, for example, by a fluid immersion method in which powder (epoxy resin) is melted by the heat of a heat-treated workpiece (base material on which a zinc plating layer is formed) to obtain a coating film. The flow-dip method is performed until the film thickness of the resin coating layer 26C is within a range of 32 μm to 40 μm. Next, magnetization processing S3 is performed on the base material on which the resin coating film of the epoxy resin is formed. Then, the magnetic characteristics and the like of the magnetized magnet are checked S4. Thus, after the inspection, the permanent magnet 26 that can be considered as a good product is obtained.
In the above examples, the example of the pressure sensor according to the present invention is applied to an electric rice cooker, but the present invention is not limited to this example, and the example of the pressure sensor according to the present invention may be applied to other cooking appliances. The lower case 10 has the mounting portions 10 formed integrally on both ends of the plate-like portion 10B so as to face each other, but the present invention is not limited to this example, and the mounting portions may be arranged on the plate-like portion 10B so that their central axes intersect at a predetermined angle.
Claims (3)
1. A pressure sensor having a corrosion-resistant magnet, comprising:
a lower case having a pressure chamber communicating with a communication path for supplying a pressure to be detected;
an upper case having a pressure-receiving-plate accommodating chamber in which a pressure-receiving plate is movably disposed in a base portion joined around a pressure chamber of the lower case, and having a pressure-receiving-plate displacement detecting portion that detects displacement of the pressure-receiving plate in accordance with the detected pressure;
a diaphragm that is elastically displaceable, has a fitting portion that is fitted to a lower end portion of the pressure receiving plate that is displaced in accordance with a pressure of the pressure chamber, and separates the pressure chamber from the pressure receiving plate accommodating chamber; and
a biasing member that is disposed in the pressure-receiving plate accommodating chamber and biases the diaphragm in a direction in which an internal volume of the pressure-receiving plate accommodating chamber increases,
the pressure receiving plate displacement detecting unit includes a magnetic sensor for detecting a magnetic flux density of the rare-earth permanent magnet held by the pressure receiving plate,
the permanent magnet has: the metal plating film is formed on the surface of the base material and has corrosion resistance to hydrogen sulfide, and the resin coating film covers the entire metal plating film and has a film thickness larger than that of the metal plating film.
2. The pressure sensor of claim 1,
the metal plating film is a zinc plating film.
3. The pressure sensor of claim 1,
the resin coating film is an epoxy resin coating film.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2019104704A JP7137531B2 (en) | 2019-06-04 | 2019-06-04 | Pressure sensor with corrosion resistant magnet |
| JP2019-104704 | 2019-06-04 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN211927164U true CN211927164U (en) | 2020-11-13 |
Family
ID=73321095
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202020989092.1U Active CN211927164U (en) | 2019-06-04 | 2020-06-02 | Pressure sensor having corrosion-resistant magnet |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JP7137531B2 (en) |
| CN (1) | CN211927164U (en) |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63161190A (en) * | 1986-12-23 | 1988-07-04 | Kawasaki Steel Corp | Corrosion-resistant steel having excellent corrosion resistance in hydrogen sulfide environment |
| JP2631493B2 (en) * | 1988-03-03 | 1997-07-16 | 住友特殊金属株式会社 | Manufacturing method of corrosion resistant permanent magnet |
| JPH04288804A (en) * | 1991-03-18 | 1992-10-13 | Tdk Corp | Permanent magnet and manufacture thereof |
| JP4665694B2 (en) * | 2005-09-30 | 2011-04-06 | Ｔｄｋ株式会社 | Rare earth magnet manufacturing method |
| JP2010515880A (en) * | 2007-01-08 | 2010-05-13 | キョントン ネットワーク コーポレーション リミテッド | Precision pressure sensor |
| JP5212205B2 (en) * | 2009-03-19 | 2013-06-19 | 新日鐵住金株式会社 | Methods for preventing corrosion of steel materials and peeling of coating films |
| JP5027191B2 (en) * | 2009-07-31 | 2012-09-19 | 株式会社鷺宮製作所 | Pressure sensor and adjustment method thereof |
-
2019
- 2019-06-04 JP JP2019104704A patent/JP7137531B2/en active Active
-
2020
- 2020-06-02 CN CN202020989092.1U patent/CN211927164U/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| JP2020198385A (en) | 2020-12-10 |
| JP7137531B2 (en) | 2022-09-14 |
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