JP5922090B2 - pressure switch - Google Patents

Description

  The present invention relates to a pressure switch.

  In an air conditioner or the like, generally, a pressure switch for detecting the pressure of refrigerant, carbon dioxide gas, or the like in a pipe and sending a detection output is provided in the pipe. As shown in Patent Document 1 and Patent Document 2, the pressure switch includes a main body case connected to the refrigerant passage through one end of the joint pipe, a diaphragm group that partitions the pressure receiving chamber in the main body case, and a displacement of the diaphragm group Accordingly, the movable contact and the fixed contact disposed in the main body case are configured to include an operation pin that can approach or separate.

  The diaphragm group is formed by overlapping a plurality of diaphragms according to the pressure in the refrigerant passage. The outer peripheral edge of the diaphragm group is sandwiched between the peripheral part of the main body case and the stopper member so as to form a pressure receiving chamber in the main body case. As the working pressure of the refrigerant passage becomes higher, pressure resistance between the peripheral edge of the main body case and the stopper member is required.

JP 2004-121140 A JP 2002-279875 A

  When pressure resistance between the peripheral edge of the main body case and the stopper member is required, a plate of the main body case and the stopper member is used to increase the clamping pressure generated between the peripheral edge of the main body case and the stopper member. While increasing the thickness, it is also conceivable to increase the necessary pressing pressure when caulking a caulking ring member as a connecting member that couples the peripheral edge of the main body case and the stopper member. Alternatively, as disclosed in Patent Document 2, it has been proposed that the shelf surface of the diaphragm holding container structure is an inclined surface.

  However, the manufacturing cost may increase with the increase in size of the pressure switch and the machining of the parts.

  In view of the above problems, the present invention is a pressure switch, which can increase pressure resistance without increasing manufacturing cost due to machining of parts, and further, the pressure switch is increased in size due to pressure resistance enhancement. An object of the present invention is to provide a pressure switch that can avoid the above.

In order to achieve the above-described object, a pressure switch according to the present invention includes a housing that houses therein a plurality of connection terminals having at least a pair of movable contacts and fixed contacts, and is connected to the housing and supplied with operating pressure. A diaphragm assembly having at least one diaphragm that is connected to a pipe line that is displaced according to an operating pressure, and an opening / closing means that opens and closes the movable contact and the fixed contact of the connection terminal according to the displacement of the diaphragm of the diaphragm assembly. The diaphragm assembly has a diaphragm whose outer peripheral edge is fixed inside the housing like a fixed beam at both ends, and a portion that is closer to the center side than the outer peripheral edge and that faces the peripheral edge of the opening end of the pipe line. It is supported by an annular elastic member.

According to the pressure switch of the present invention, the diaphragm of the diaphragm assembly is
The outer peripheral edge is fixed inside the housing like a fixed beam at both ends, and the part closer to the center side than the outer peripheral edge and facing the peripheral edge of the opening end of the pipe line is supported by an annular elastic member. As a result, the maximum stress of the diaphragm can be reduced, so that the pressure resistance can be increased without increasing the manufacturing cost, and the enlargement of the pressure switch accompanying the enhancement of the pressure resistance can be avoided.

It is sectional drawing which shows the principal part of an example of the pressure switch which concerns on this invention. It is sectional drawing of the diaphragm assembly used for another example of the pressure switch which concerns on this invention. (A) And (B) is a fragmentary sectional view used for operation | movement description of an example of a prior art example and a pressure switch which concerns on this invention, respectively. It is a figure with which it uses for description of the bending of the diaphragm group of a prior art example. It is a figure with which it uses for description of the bending of the diaphragm group used for an example of the pressure switch which concerns on this invention. It is a characteristic view which shows the change of the deflection coefficient according to an inside diameter radius ratio. It is a characteristic view which shows the change of the stress coefficient according to an internal diameter radius ratio.

  FIG. 1 shows a main part of an example of a pressure switch according to the present invention.

  The pressure switch is attached to, for example, a hydraulic device (not shown) or a pipe that supplies air, refrigerant, water, or the like via a connection joint 28.

  As shown in FIG. 1, the pressure switch is a normally closed switch, and is connected to a diaphragm assembly 20 coupled to one end of a connection joint 28 and a diaphragm assembly 20, and a pair of connection terminals 12 and 14 to be described later are connected. A built-in case 10, a shaft 16 </ b> P that opens and closes a fixed contact 12 a of the pair of connection terminals 12 and a movable contact 14 a of the connection terminal 14 according to the displacement of the diaphragm group 20 </ b> B, which will be described later, are disposed in the case 10. A shaft guide member 16 for guiding is included as a main element.

  The case 10 as a housing is formed of, for example, a resin material, and a fixed contact 12a of a pair of connection terminals 12 as a plurality of connection terminals, a movable piece 14b of the connection terminal 14, and a concave portion in which the movable contact 14a is accommodated inside. Have. The external connection portion of the connection terminal 12 protrudes outside through the slit of the case 10. The external connection portion of the connection terminal 14 protrudes to the outside through the slit of the case 10 so as to be substantially parallel to the external connection portion of the connection terminal 12. The external connection portions of the connection terminals 12 and 14 are connected to a control circuit (not shown), for example. Thereby, as shown in FIG. 1, when the fixed contact 12a and the movable contact 14a are in contact with each other, the connection terminals 12 and 14 supply a signal representing an ON state to the control circuit via the external connection unit. . Further, the connection terminals 12 and 14 supply a signal representing an OFF state to the external connection portion when the fixed contact 12a and the movable contact 14a are separated from each other.

  In the above example, the connection terminals 12 and 14 are single-pole single-throw types, but are not limited to such examples. For example, the single-pole double-throw type, double-pole single-throw type, double-pole double-throw type, and the like. A switch that is a three-pole single-throw type or a three-pole double-throw type may be configured.

  The shaft guide member 16 has a through hole at the center portion into which the shaft 16P is movably inserted. The outer peripheral edge of the shaft guide member 16 is fitted to an opening end portion that communicates with the recess of the case 10. An O-ring 18 is disposed across the annular groove formed at the outer peripheral edge of the shaft guide member 16 and the groove formed at the opening end of the case 10.

  As shown in FIG. 1, one end of the shaft 16 </ b> P is opposed to the protrusion of the movable piece 14 b of the connection terminal 14 through the through hole of the shaft guide member 16 with a predetermined interval. The other end of the shaft 16P is brought into contact with the substantially central portion of the end face of the diaphragm group 20B through the through hole 20a of the upper plate 20A of the diaphragm assembly 20. Thus, one end of the shaft 16P is connected to the movable piece 14b of the connection terminal 14 in accordance with the displacement of the substantially central portion of the end face of the diaphragm group 20B caused by the operating pressure of the fluid supplied through the flow path 28a in the connection joint 28. It can be moved toward or away from the protrusion. Therefore, the fixed contact 12a and the movable contact 14a in the connection terminals 12 and 14 are opened and closed by the movement of one end of the shaft 16P according to the operating pressure of the fluid supplied through the flow path 28a in the connection joint 28.

  The diaphragm assembly 20 includes an upper plate 20A that is in contact with the peripheral edge of the opening end of the case 10 and the O-ring 18, a lower plate 20C that is connected to one end of the connection joint 28, and an upper plate 20A and a lower plate 20C that face each other. The diaphragm group 20 </ b> B sandwiched between the two and the O-ring 24 as an annular elastic member are configured as main elements.

  The upper plate 20A is formed of, for example, a metal material by press molding, cutting, die casting, forging, or the like, and is disposed so as to face the end surface of the shaft guide member 16 with a predetermined gap. The upper plate 20A has a through hole 20a in the center portion through which the other end of the shaft 16P passes.

  The lower plate 20C is formed of, for example, a metal material by press molding, cutting, die casting, forging, or the like, and has a hole into which the end of the connection joint 28 is fitted. An annular groove into which the O-ring 24 is inserted is formed concentrically on the periphery of the hole of the lower plate 20C. The O-ring 24 as an elastic member is formed of a material having heat resistance. The inner diameter 2b of the O-ring 24 is set smaller than the outer diameter 2a of a plurality of diaphragms 20bi (i = 1 to n, n is a positive integer) constituting the diaphragm group 20B. At that time, the outer peripheral edge of the diaphragm group 20B is sandwiched between the upper plate 20A and the lower plate 20C. Further, a portion closer to the center side than the outer peripheral edge of the diaphragm group 20 </ b> B is supported by the O-ring 24.

  Between the lower plate 20C and the diaphragm group 20B facing each other, a pressure receiving chamber is formed by the surface of the diaphragm 20bi, the end surface of the lower plate 20C, and the inner peripheral portion of the O-ring 24.

  The plurality of diaphragms 20bi constituting the diaphragm group 20B are formed of, for example, a material having corrosion resistance against the fluid supplied through the flow path 28a in the connection joint 28. In addition, the number of the plurality of diaphragms 20bi constituting the diaphragm group 20B is appropriately selected according to the specifications of the pressure switch.

  The upper plate 20 </ b> A and the lower plate 20 </ b> C are joined together by welding their outer peripheral edges while sandwiching the diaphragm group 20 </ b> B, whereby the diaphragm assembly 20 is obtained. Thereby, the fusion | melting part 20D is formed in the outer peripheral part of 20 A of upper plates, and the lower plate 20C. Then, the obtained diaphragm assembly 20 and the above-described case 10 are coupled by the connecting metal fitting 26.

  The above-described diaphragm assembly 20 has a relatively high pressure specification even if the pressure receiving area of the diaphragm group 20B is reduced due to the reason described later as compared to the structure of the conventional diaphragm assembly as shown in Patent Document 1 and Patent Document 2. Thus, it can be seen that the structure can reduce the variation in the accuracy of the operating pressure, and reduce the maximum bending stress acting on the diaphragm group 20B while suppressing the decrease in the deflection of the diaphragm group 20B within a predetermined range. Therefore, the pressure resistance of the pressure switch is improved.

In the case of the structure of the conventional diaphragm assembly as shown in Patent Document 1 and Patent Document 2, as shown in FIGS. 3A and 4, the outer peripheral edge of the diaphragm group 20′B is the upper plate 20 ′. A and the lower plate 20'C are clamped like a fixed beam at both ends. In such a case, the deflection ω, the radial stress σ _r , and the circumferential stress σ _{θ of} the diaphragm group 20′B are obtained based on the following formulas (1) to (3).

  Where p, a, D, r, ν, and h are the load per unit area, the radius of the surface that receives the stress, the bending rigidity, the distance from the center, the Poisson's ratio, and the sum of the multiple diaphragms 20bi superimposed. The plate thickness. In addition, the bending rigidity D is represented by Formula (4). However, E is a longitudinal elastic modulus.

The maximum deflection ω _max is obtained by the following equations (5) and (5 ′) based on the equations (1) and (4).

  If ∵ν = 0.3,

The maximum radial stress σ _max is obtained by Expression (6) based on Expression (2) (r = a).

On the other hand, in the example of the pressure switch according to the present invention, as shown in FIGS. 3B and 5, the outer peripheral edge of the diaphragm group 20B is sandwiched between the upper plate 20A and the lower plate 20C like a both-end fixed beam. When the portion closer to the center than the outer peripheral edge of the diaphragm group 20B is supported by the O-ring 24, the deflection ω of the diaphragm group 20B based on the following formulas (7) to (9): Radial stress σ _r and circumferential stress σ _θ are obtained. However, p, a, D, r, ν, h, and b are respectively the load per unit area, the radius of the surface subjected to stress, the bending rigidity, the distance from the center, the Poisson's ratio, and a plurality of superimposed diaphragms 20bi. The total plate thickness and the radius of the surface subjected to stress. The bending rigidity D is represented by the above formula (4).

(I) When 0 ≦ r ≦ b

(Ii) When b ≦ r ≦ a

The maximum deflection ω _max is obtained by equation (10) obtained by substituting equation (4) into equation (7) (r = 0).

Maximum bending stress σ _max when b / a <0.569 (when stress is concentrated in the center)

  It should be noted that the place where the bending stress is maximized is when the stressed width is small, the stress collects in the center and becomes the central portion of the disk, that is, where r = 0, and the stressed width. Is large, the stress is a fixed portion of the disk, that is, where r = a. The switching point changes depending on whether the inner radius ratio b / a is larger or smaller than the value INF (= 0.568) (see FIG. 7).

  When b / a> 0.569 (when the disc is stressed widely)

Hereinafter, the next part of the expression (10 ′) is referred to as a deflection coefficient α ₆ , and the next part of the expressions (11) and (12) is referred to as a stress coefficient β ₆ and β ₆ ′, respectively.

When b / a <0.569

When b / a> 0.569

When the Poisson's ratio ν is 0.3, the deflection coefficient α _{6 and the} stress coefficients β ₆ and β ₆ ′ change as shown in FIG. 6 and FIG. 7 according to the change of the inner radius ratio b / a. To do. As is apparent from FIGS. 6 and 7, when the inner radius ratio b / a is 1, the deflection coefficient α ₆ matches the equation (5 ′), and the stress coefficient β ₆ ′ becomes the equation (6). Match.

For example, when 2a = φ20 and 2b = φ12, b / a = 0.6. Further, when the Poisson's ratio is 0.3, by applying the equations (13) and (15), as shown in FIGS. 6 and 7, α ₆ = 0.134, β ₆ ′ = 0. 443 is obtained.

Thus, when the change amount of the maximum deflection ω _{max and} the change amount of the maximum bending stress σ _max are calculated, the change amount of the maximum deflection ω _max is 21.6% (= (0.171−0.134) / 0). .171 × 100), and the amount of change in the maximum bending stress σ _max is 40.9% (= (0.75−0.443) /0.75×100). That is, the change in “deflection” that seems to be related to the pressure characteristics of the diaphragm group 20B is reduced by about 21.6%, while the “maximum bending stress σ _max ” value of the diaphragm group 20B is reduced by about 40.9%. It becomes possible to make it.

  FIG. 2 shows a main part of another example of the pressure switch according to the present invention.

  In the example shown in FIG. 2, the pressure switch is a normally closed switch as shown in FIG. 1, and is connected to the diaphragm assembly 30 coupled to one end of the connection joint 28, and the diaphragm assembly 30. A case 10 containing a pair of connection terminals 12 and 14, and a fixed contact 12a of the pair of connection terminals 12 and a movable contact 14a of the connection terminal 14 in accordance with the displacement of a diaphragm group 30B, which will be described later. A shaft 16P that opens and closes and a shaft guide member 16 that guides the shaft 16P are included as main elements.

  The diaphragm assembly 30 includes an upper plate 30A that is in contact with the peripheral edge of the opening end of the case 10 and the O-ring 18, a lower plate 30C that is connected to one end of the connection joint 28, and an upper plate 30A and a lower plate 30C that face each other. The main components are a diaphragm group 30B sandwiched between the two, an O-ring 34 as an annular elastic member, and a backup ring 36.

  The upper plate 30A is formed of, for example, a metal material by press molding, cutting, die casting, forging, or the like, and is disposed so as to face the end surface of the shaft guide member 16 with a predetermined gap. The upper plate 30A has a through hole 30a in the center portion through which the other end of the shaft 16P passes.

  The lower plate 30C is formed of, for example, a metal material by press molding, cutting, die casting, forging, or the like, and has a hole into which the end of the connection joint 28 is fitted. An annular groove into which the O-ring 24 and the backup ring 36 are inserted is formed concentrically on the periphery of the hole of the lower plate 30C. The O-ring 34 and the backup ring 36 as elastic members are formed of a material having heat resistance. An inner diameter 2b of the O-ring 34 is set smaller than an outer diameter 2a of a plurality of diaphragms 30bi (i = 1 to n, n is a positive integer) constituting the diaphragm group 30B. At that time, the outer peripheral edge of the diaphragm group 30B is sandwiched between the upper plate 30A and the lower plate 30C. Further, the portion closer to the center side than the outer peripheral edge of the diaphragm group 30 </ b> B is supported by the backup ring 36 and the O-ring 34.

  Between the lower plate 30C and the diaphragm group 30B facing each other, a pressure receiving chamber is formed by the surface of the diaphragm 30bi, the end surface of the lower plate 30C, and the inner peripheral portion of the O-ring 34.

  The plurality of diaphragms 30bi constituting the diaphragm group 30B are formed of, for example, a material having corrosion resistance against the fluid supplied through the flow path 28a in the connection joint 28. The number of the plurality of diaphragms 30bi constituting the diaphragm group 30B is appropriately selected according to the specifications of the pressure switch.

  The upper plate 30 </ b> A and the lower plate 30 </ b> C are joined together by welding the outer peripheral edges with the diaphragm group 30 </ b> B sandwiched therebetween, whereby the diaphragm assembly 30 is obtained. Thereby, the fusion | melting part 30D is formed in the outer peripheral part of 30 A of upper plates, and the lower plate 30C. Then, the obtained diaphragm assembly 30 and the above-described case 10 are coupled by the connecting metal fitting 26.

  Also in such an example, the maximum bending stress value acting on the diaphragm group 30B can be reduced while suppressing a decrease in the deflection of the diaphragm group 30B within a predetermined range.

  In the example of the present invention, the O-rings 24 and 34 are used as the elastic member, which is applied to a normally closed type switch. However, the present invention is not limited to such an example. A V-shaped ring having elasticity as an elastic member, a square ring, a sealing member having elasticity, an adhesive having elasticity, or a sealing material may be used.

12, 14 Connection terminal 12a Fixed contact 14a Movable contact 20, 30 Diaphragm assembly 20A, 30A Upper plate 20B, 30B Diaphragm group 20bi, 30bi Diaphragm 20C, 30C Lower plate 24, 34 O-ring 36 Backup ring

Claims (3)

A housing that houses therein a plurality of connection terminals having at least a pair of movable contacts and fixed contacts;
A diaphragm assembly coupled to the housing and having at least one diaphragm connected to a conduit to which an operating pressure is supplied and displaced in accordance with the operating pressure;
Opening and closing means for opening and closing the movable contact and the fixed contact of the connection terminal according to the displacement of the diaphragm of the diaphragm assembly,
The diaphragm of the diaphragm assembly is a portion whose outer peripheral edge is fixed in the housing like a fixed beam at both ends, and is a portion closer to the center than the outer peripheral edge and facing the peripheral edge of the opening end of the pipe line Is supported by an annular elastic member.   The pressure switch according to claim 1, wherein the annular elastic member is disposed adjacent to a backup ring.   The pressure switch according to claim 1, wherein the annular elastic member has a diameter smaller than a diameter of the diaphragm of the diaphragm assembly.

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