JPH0528501Y2 - - Google Patents

Description

[Detailed explanation of the idea]

【0001】

[Industrial Application Field] The present invention deforms a pressure receiving diaphragm using fluid as a pressure medium, detects the deformation of the pressure receiving diaphragm with a strain gauge attached to the diaphragm, and obtains an electrical signal corresponding to the applied pressure. It is related to vessels.

【0002】

[Prior Art] Conventionally, this type of pressure transducer is
For example, it was configured as shown in FIG. In FIG. 5, reference numeral 1 indicates that this pressure transducer is connected and fixed to a device, container, pipe line, etc. as a pressure detection object, and a gas as a pressure medium is transferred from the object.
This is an introduction part for introducing fluid such as fluid.

[0003] This introduction part 1 has a fitting hole 1a which is a fluid introduction path in the center, and a threaded part 1b as a mounting part is formed on the outer peripheral surface on one end side, and the threaded part 1b is formed on the other end side as a mounting part. A step is formed with respect to 1b to form a substantially flange-like large diameter portion 1c whose outer circumferential surface is similarly threaded.

[0004] Reference numeral 2 denotes an outer cylinder portion formed in a cylindrical shape, and one end thereof is a threaded portion 2a that is threaded on the inner circumferential surface. It is threadedly engaged with a threaded portion formed in and welded to the introduction part 1 by welding or the like.

[0005] In addition, in the middle of the outer cylinder part 2, a thin plate-shaped pressure receiving diaphragm 2b is installed so as to close the hollow part.
are integrally formed. Then, on the back surface of this pressure receiving diaphragm 2b (the surface opposite to the pressure receiving surface),
A strain gauge 3 that deforms together with the pressure receiving diaphragm 2b and converts the pressure applied to the pressure receiving diaphragm 2b into an electrical signal is attached with an adhesive or the like. Reference numeral 4 denotes a relay board fixed to the other end of the outer cylinder part 2 and electrically connected to the strain gauge 3. 5 is a case in which one end is fixed to the outer periphery of the protruding end of the outer cylindrical portion 2 by welding or the like.

[0006] 6 is a waterproof connector whose one end is fitted into the other end of the case 5 and is electrically connected to the relay board 4 to output a converted output (electrical signal) to the outside;
8 is a fixing fitting for fixing the waterproof connector 6 to the case 5, and 8 is the case 5 and the waterproof connector 6.
This is an O-ring for sealing the joint of the

[0007] With such a configuration, the liquid led from the object such as a pressure vessel through the introduction section 1,
The pressure of the fluid such as gas deforms the pressure receiving diaphragm 2b, and the strain gauge 3 attached to the pressure receiving diaphragm 2b detects the strain and outputs an electrical signal corresponding to the applied pressure. Incidentally, among the members constituting this pressure transducer, the outer cylinder portion 2 including the pressure receiving diaphragm 2b is integrally formed by cutting a bar-shaped steel material such as stainless steel with a lathe or the like.

[0009] By integrally forming the pressure receiving diaphragm 2b in this way, the relationship between the output of the strain gauge 3 and the fluid pressure from the target object is made linear and hysteresis is reduced, and a highly accurate and stable pressure transducer can be obtained. It will be done.

【0010】

[Problems to be Solved by the Invention] However, when processing the outer cylinder portion 2 in this manner, several problems occurred.

[0011] First of all, the processing of the outer cylindrical portion 2 requires a large number of so-called machining steps, such as thread cutting of the threaded portion 2a, cutting of the pressure receiving diaphragm 2b, and cutting of the outer peripheral surface and end surface. The diaphragm 2b has to be formed into a thin plate shape and requires extremely high precision, so the cutting process requires great care and takes a long time. Thirdly, when assembling the pressure transducer, There is a risk that the pressure-receiving diaphragm 2b may be deformed when the introduction part 1 and the outer cylinder part 2 are screwed together, causing a change in the zero point of the conversion output, and that it is necessary to be extremely careful in the assembly work; Second, there is a problem regarding the material of the pressure receiving diaphragm 2b.

[0012] That is, it is essential for the pressure receiving diaphragm 2b to have corrosion resistance against liquid and fluid as a pressure medium for long-term stability, and the strain gauge 3 is attached to the pressure receiving diaphragm 2b. For this reason, the material is required to have high tensile strength.

[0013] Conventionally, as a pressure receiving diaphragm 2b,
There were some that used austenitic stainless steel such as 18-8 stainless steel, but in this case there was no problem in terms of corrosion resistance, but there were some problems in terms of tensile strength.

[0014] In addition, 18-8 stainless steel does not harden even after heat treatment and cannot be used as a diaphragm as an elastic material, but it shows remarkable work hardening properties when rolled into a thin plate. If the diaphragm could be formed by rolling the outer cylindrical portion 2 using the same method, it would be sufficient to use the diaphragm, but due to its shape, rolling is practically impossible.

[0015] On the other hand, when precipitation hardening stainless steel such as 17-4PH steel is used as a material, it is possible to obtain an extremely high-precision pressure transducer that satisfies both corrosion resistance and tensile strength. However, the cost of the material itself is diverse and machining is relatively difficult, so there was a problem in that the cost of the pressure transducer increased significantly.

[0016] In order to avoid this problem, if the material of the introduction part 1 is made different from the material of the outer cylinder part, if these expansion rates are different, when a temperature change occurs in the pressure transducer, the introduction part 1 A new problem arises in that thermal strain (thermal stress) occurs in the threaded portion of the large diameter portion 1c of the portion 1 and the threaded portion 2a of the outer cylinder portion 2, deforming the pressure receiving diaphragm 2b and causing errors. Occur.

[0017] Therefore, it is necessary to use a material for the introduction part 1 that is the same as the outer cylinder part 2, or at least one that can be considered to have the same expansion rate. For example, the outer cylinder part 2 is made of 17-4PH steel. If such an expensive material is used, 17-4PH steel must be used for the introduction section as well, making it impossible to reduce the overall cost of the pressure transducer.

[0018] Under these circumstances, the demand for pressure transducers has increased with the recent increase in the number of various hydraulic control devices, and it is desired that low-cost pressure transducers be supplied in large quantities for locking. It is rare.

[0019] Therefore, one of the countermeasures is to reduce the number of parts by configuring the threaded part 2a of the outer cylinder part 2 to be directly attached to the object without using the introduction part 1, thereby reducing costs. There are ways to do this.

[0020] However, in the case of this method, when the introduction part 1 is screwed onto the object, stress is generated in the threaded part 2a, and the stress deforms the pressure receiving diaphragm 2b, causing initial fluctuation (initial movement). There is a risk. Therefore, there are various restrictions in putting it into practical use. Further, it would be possible to manufacture a member that integrates the introduction part 1 and the outer cylinder part 2, but this is not possible due to its shape.

[0021] In addition, as another countermeasure, it is conceivable to construct the outer cylinder portion and the diaphragm from separate members as shown in FIG.

[0022] That is, the introduction part 9 is similar to the introduction part 1 in FIG. An edge portion 10b having a shape as if folded in is formed.

[0023] Then, the pressure receiving diaphragm 11 formed in the shape of a thin disk is held between the other end surface of the introduction part 9 and the edge part 10b of the outer cylinder part 10 screwed thereto. When configured in this way, the pressure receiving diaphragm 11
Since it is a separate member, only the pressure receiving diaphragm 11 can be made of, for example, 17-4PH steel, or it is also possible to roll inexpensive 18-8 stainless steel and increase its tensile strength through work hardening. Therefore, it is possible to manufacture a pressure transducer that is cheaper than conventional pressure transducers.

[0024] However, by simply sandwiching the pressure receiving diaphragm 11 in the introduction part 9 in this way, it is not possible to firmly fix the pressure receiving diaphragm 11 without causing stress on the peripheral edge of the pressure receiving diaphragm 11. Hysteresis in the output increases and the accuracy of the pressure transducer deteriorates.

[0025] In the end, conventional pressure transducers have the problem that if you try to manufacture a pressure transducer with high precision and long-term stability, the price increases, and conversely, if you try to reduce the cost, the precision decreases. It was hot.

[0026] The present invention was created in view of the above-mentioned problems, and its purpose is to reduce cost, weight, and ease of processing without causing deterioration of characteristics and sensitivity compared to conventional ones. The object of the present invention is to provide a pressure transducer that can be mass-produced in addition to high precision machining.

【0027】

[Means for Solving the Problems] In order to achieve the above object, the present invention deforms a pressure receiving diaphragm using fluid as a pressure medium, and detects the deformation of the pressure receiving diaphragm using a strain gauge attached to the pressure receiving diaphragm. In a pressure transducer that obtains an electrical signal corresponding to an applied pressure, a mounting portion is formed at one end so that it can be coupled and fixed to a pressure detection object, and a mounting portion is formed at one end to guide the fluid from the pressure detection object. an introduction part having an introduction passage penetrating through the side, and further formed with a thin ring-shaped protrusion having the same height on the end face of the other end side so as to surround the outlet of the introduction passage; and at least an expansion part. 18-8 stainless steel, which has approximately the same ratio as the introduction part and does not harden or increase its strength even after heat treatment, but its yield strength and tensile strength can be increased by rolling. It consists of a pressure-receiving diaphragm made of a material such as steel and formed into a thin plate shape that can be deformed in response to the pressure of the fluid, and the protruding part of the introduction part and the pressure-receiving diaphragm are pre-rolled to have a The diaphragm and the peripheral edge of the diaphragm having increased tensile strength are integrally welded together by electric welding means such as projection welding or beam welding.

【0028】

[Function] In the pressure transducer configured as described above, the introduction part and the pressure receiving diaphragm are formed separately to facilitate processing of the pressure receiving diaphragm and to increase yield strength and tensile strength. .

[0029] That is, by making the pressure-receiving diaphragm separate and plate-shaped, it is possible to perform rolling processing and punching processing, thereby facilitating processing and realizing mass production.

[0030] In addition, by using a material for the pressure receiving diaphragm that cannot increase its tensile strength even by heat treatment, such as 18-8 stainless steel, and rolling the pressure receiving diaphragm in advance, the yield strength and tensile strength can be increased. I'm trying to increase that.

[0031] As a means of fixing the pressure receiving diaphragm and the introduction part that supports it, instead of simply welding, the pressure receiving diaphragm is deformed during welding so that the zero point of the conversion output does not fluctuate and the strain is reduced. In order to prevent temperature rise due to heating of the gauge and stress on the periphery of the pressure-receiving diaphragm, a thin ring-shaped protrusion of the same height is installed on the end face of the inlet so as to surround the outlet of the inlet. The projecting portion and the peripheral edge of the pressure receiving diaphragm are welded together by projection welding or electron beam welding.

【0032】

[Embodiment] The present invention will be described in detail below based on an illustrated embodiment. FIG. 1 is a longitudinal sectional view showing the configuration of an embodiment of the present invention.

[0033] In FIG. 1, an introduction part 12 that is fixedly connected to a container, a pipe line, etc. as a pressure detection target and introduces a fluid as a pressure medium has a through hole 12a in the center that is an introduction path for the fluid. At the same time, a threaded portion 12b as a mounting portion is formed on the outer circumferential surface of one end, and a threaded portion 12b is formed on the other end.
A large-diameter portion 12c having a substantially flange-like shape is formed with a step difference relative to b.

[0034] A large diameter opening 12d has a diameter smaller than the diameter of the large diameter portion 12c and larger than the diameter of the through hole 12a, and reaches a predetermined depth from the other end surface.
is formed.

[0035] Then, on the other end side of the introduction part 12, there is a protruding part 12e that is thin and has a ring shape of the same height so as to surround the large diameter opening 12d that communicates with the outlet of the through hole 12a. It is formed.

[0036] On the other hand, the pressure receiving diaphragm 13 is rolled separately from the introduction part 12, and is made of a material with at least the same expansion rate as the introduction part 12, to the extent that it can be deformed in response to the pressure caused by the fluid. It is formed into a thin disk shape.

[0037] Then, during assembly, the introduction section 1
The peripheral edge of the pressure-receiving diaphragm 13 is brought into contact with the protrusion 12e formed protrudingly on the other end surface of the electrode 12, and in this state, a large current (several hundreds to (about several tens of KA)
energize.

[0038] Then, this current passes through the contact surface between the protrusion 12e and the pressure receiving diaphragm 13, that is, the ring-shaped contact area with a small contact area, so that the current passes through a part of the protrusion 12e and the pressure receiving diaphragm 1.
The contact portion of No. 3 is melted.

[0039] As a result, the introduction section 12 and the pressure receiving diaphragm 13 are welded and integrated, and the other end side of the introduction section 12 is closed. According to such a resistance welding method, welding can be performed in an extremely short time, and since the heat generated during welding is localized, there is almost no deformation or change in the characteristics of the pressure receiving diaphragm 13 due to thermal effects or residual stress.

[0040] FIG. 2 is a schematic cross-sectional view for explaining another method of electric welding. The method shown in this figure is called the electron beam welding (EBW) method, in which an electron beam (electron beam) accelerated by an electron gun 15 at a high voltage of tens of thousands of V in a vacuum is applied to a pressure receiving diaphragm 1.
3, shock heat is generated locally, and this heat causes wedge-shaped melting from the pressure receiving diaphragm 13 to the protruding portion 12e of the introduction part 12, and as a result, the introduction part 12 and the pressure receiving diaphragm 13 are welded together. Ru.

[0041] According to this electron beam welding, unlike in the case of resistance welding, the object to be welded does not need to be a conductor, and welding can be performed in a short time and extremely locally, and the welding can also be strong. can be done, and also
Similar to resistance welding, thermal effects and residual stress are extremely low.

[0042] Of the pressure-receiving diaphragm 13 welded to the introduction part 12 in this way, the surface (back surface) opposite to the pressure-receiving surface that receives fluid pressure has a diaphragm shown in FIGS. 3 and 4.
As shown in , four strain gauges G1, G2,
G3 and G4 are attached on a line perpendicular to the center line of the pressure receiving diaphragm 13.

[0043] Among these strain gauges G1 to G4, the strain gauges G1 and G4 attached to positions near the periphery of the pressure receiving diaphragm 13 are used for compressing when the pressure receiving diaphragm 13 receives fluid pressure, as shown in FIG. A strain gauge G that detects strain and is attached to a position near the center of the pressure receiving diaphragm 13
2, G3 detects tensile strain.

[0044] And these strain gauges G1~
For example, G4 is constructed with a Wheatstone bridge such that strain gauges G1 and G4, which detect compressive strain, are on opposite sides, and strain gauges G2, G3, which detect tensile strain, are on the other opposite side, and the input of this bridge is By applying a bridge power source to the end, an electrical signal corresponding to the fluid pressure can be obtained from the output end.

[0045] By the way, the pressure receiving diaphragm 13 is
Since its shape is a flat plate, it can be formed from various materials by rolling, as long as it can be considered to have at least the same coefficient of expansion as the introduction part 12. For example, the introduction portion 12 may be made of a bar made of 18-8 stainless steel, and the pressure-receiving diaphragm 13 may be made of 18-8 stainless steel, which is cold-worked by rolling.

[0046] Incidentally, when comparing the mechanical properties of this 18-8 stainless steel, when it is used as a bar, the yield strength is only 21Kgf/mm ² and the tensile strength is only 53Kgf/mm ² . By rolling this, the yield strength increases.
The tensile strength is 48Kgf/mm ² and the tensile strength is 80Kgf/mm ² . Therefore, in the case of a bar material, there has been a problem in the past in terms of tensile strength as the pressure receiving diaphragm 13, but a bar material that is rolled has an increased tensile strength, so there is no problem at all.

[0047] Furthermore, if the cost of the material is not important, precipitation hardening stainless steel such as 17-4PH steel may be used for the introduction part 12 and the pressure receiving diaphragm 13. Incidentally, the mechanical properties of this 17−4PH steel are such that the yield strength is
Since the tensile strength is as high as 120Kgf/mm ² and 134Kgf/mm ² , it is possible to manufacture a transducer with a higher output.

[0048] According to the embodiment configured as described above, the pressure receiving diaphragm 13 is connected to the fluid introduction part 12.
Since the pressure receiving diaphragm 13 can be formed separately and in the form of a flat plate, it is possible to freely manufacture the pressure receiving diaphragm 13 with extremely high precision by rolling, polishing, etc.

[0049] Furthermore, in the embodiment described above, a method was adopted in which the pressure receiving diaphragm 13 was separated from the introduction part 12 that supported it, and the pressure receiving diaphragm 13 was fixed by welding.

[0050] Therefore, instead of simply welding, a ring-shaped protrusion 1 is attached to the end surface of the introduction part 12.
2e, and welded the protruding portion 12e and the peripheral edge of the pressure receiving diaphragm 13 by resistance welding or beam welding, etc., so that the pressure receiving diaphragm 13 can be attached to the introduction part in a state where there is little influence of heat or residual stress. 12, the nonlinearity between the strain of the pressure receiving diaphragm 13 and the fluid pressure is almost the same as that of the conventional one, and the hysteresis characteristics are slightly worse, but We were able to keep the degree within the margin of error.

[0051] A further advantage of this embodiment is that it is possible to reduce the number of man-hours and time in the manufacturing process of the introduction section 12 and the pressure receiving diaphragm 13.

[0052] That is, there is no need to form a threaded part on the introduction part 1 as in the conventional one (FIG. 5), and there is no need to cut the outer cylinder part 2 using a time-consuming lathe. Because it can be manufactured by punching a rolled material, which takes a much faster processing time than cutting, the processing time can be significantly shortened, and together with the ability to use inexpensive materials, the cost can be significantly reduced. can be reduced to

[0053] Incidentally, when 18-8 stainless steel is used as the material, the pressure transducer of this embodiment can be manufactured at 1/5 to 1/3 the cost of a conventional one.

[0054] Furthermore, when precipitation hardening stainless steel such as the aforementioned 17-4PH steel is used as the material for the introduction part 12 and the pressure receiving diaphragm 13, a pressure transducer with a large rated output and small hysteresis characteristics can be obtained. be able to.

[0055] In this case, it is undeniable that the cost will be high because precipitation hardening stainless steel is expensive as a material, but since the manufacturing man-hours are reduced and the manufacturing time of the pressure receiving diaphragm 13 is significantly shortened, the pressure transducer Overall, it can be made cheaper than conventional products.

[0056] Furthermore, since the outer cylinder portion 2 of the conventional pressure transducer shown in FIG. 5 can be made thinner or unnecessary, the weight can be reduced accordingly.

[0057] It goes without saying that the present invention is not limited to the above-described embodiments, and that various modifications, substitutions, etc. can be made without departing from the spirit of the invention. For example, as a method for welding the introduction part 12 and the pressure receiving diaphragm 13, other welding methods other than those described above may be used as long as they do not give the pressure receiving diaphragm 13 any influence of heat or residual stress. You can do it like this.

[0059] Furthermore, as the material for the introduction part 12 and the pressure receiving diaphragm 13, other materials than stainless steel may be used as long as they have corrosion resistance and high tensile strength.

【0060】

[Effects of the invention] As detailed above, according to the invention, the pressure-receiving diaphragm is separate from the fluid introduction part, and since it is in the form of a flat plate, high precision can be achieved with a simple process of thickly rolling a plate material. To provide a pressure transducer that can be manufactured in large quantities and at low cost, and in which a pressure-receiving diaphragm with high yield strength and tensile strength can be manufactured at low cost by simply rolling a relatively inexpensive material such as 18-8 stainless steel in advance. can do.

[0061] Furthermore, according to the present invention, the pressure-receiving diaphragm and the introduction part that supports it are separated and fixed by welding. However, rather than simply welding, While solving the problems, in other words, the pressure receiving diaphragm is not deformed during welding and the zero point of the conversion output does not fluctuate, the temperature does not increase due to heating of the strain gauge, and stress is not generated at the periphery of the pressure receiving diaphragm. In order to satisfy the conditions that no damage occurs, a thin ring-shaped protrusion of the same height is formed on the end face of the introduction part so as to surround the outlet of the introduction passage, and the protrusion and the periphery of the pressure receiving diaphragm are Since the pressure-receiving diaphragm is welded by projection welding, electron beam welding, etc., the pressure-receiving diaphragm can be firmly fixed to the introduction part with less influence of heat and residual stress.

[0062] In addition, the nonlinearity between the strain of the pressure receiving diaphragm and the fluid pressure is almost the same as that of the conventional one, and although the hysteresis characteristics are slightly deteriorated, the degree of pressure conversion can be kept within the error range. equipment can be provided.

[0063] Furthermore, according to the present invention, it is possible to omit the thick-walled and highly rigid outer cylinder part formed by a diaphragm, as in the conventional example, resulting in a lighter and less expensive pressure conversion system. equipment can be provided.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing the configuration of an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view for explaining an example of the processing method of the present invention.

3 is a rear view for explaining the operation of the embodiment shown in FIG. 1. FIG.

4 is a partial vertical sectional view for explaining the operation of the embodiment shown in FIG. 1. FIG.

FIG. 5 is a longitudinal sectional view showing an example of a conventional pressure transducer.

FIG. 6 is a longitudinal sectional view showing the configuration of a reference example designed to partially improve the drawbacks of the conventional pressure transducer.

[Explanation of symbols]

12...Introduction 12a...Through hole 12b...screw part 12c...Large diameter part 12d...Large diameter opening 12e... protrusion 13...Pressure diaphragm 14...electrode 15...Electron gun G1~G4...Strain gauge.

Claims (1)

[Scope of utility model registration request] 1. A pressure transducer that deforms a pressure receiving diaphragm using fluid as a pressure medium, detects the deformation of the pressure receiving diaphragm with a strain gauge attached to the pressure receiving diaphragm, and obtains an electrical signal corresponding to the applied pressure. A mounting portion is formed at one end so as to be able to be coupled and fixed to a target object, and an introduction passage is bored through from one end side to the other end side to guide the fluid from the pressure detection target object, and further, an end face on the other end side. an introduction part in which a thin ring-shaped protrusion of the same height is formed so as to surround the outlet of the introduction passage, and the expansion coefficient is at least approximately the same as that of the introduction part and hardens even when heat treated. Strength cannot be increased even without heat treatment, but yield strength and tensile strength can be increased by rolling.18
- A pressure-receiving diaphragm made of a material such as 8 stainless steel and formed into a thin plate shape that can be deformed in response to the pressure of the fluid, and the protruding part of the introduction part and the pressure-receiving diaphragm are pre-rolled. A pressure transducer characterized in that the diaphragm and the peripheral edge of the diaphragm, which have increased yield strength and tensile strength, are integrally welded by electric welding means such as projection welding or beam welding.