JPH11297303A - Pressure cut-off sensor and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure cut-off sensor which is capable of shortening a manufacturing time and having a diaphragm part capable of surely breaking a cut-off member. SOLUTION: In this pressure cut-off sensor 1, a cut-off member 7 is arranged in the upper side of a diaphragm part D, the diaphragm part D has a connecting part 4d formed with portion a made thin for a cover body 4, and a protrusion 4e projected toward a cut-off member 7 side in the vicinity of the central part of the connecting part 4d, an outer circumferential part side of the connecting part 4d is thinned, the vicinity of the central part of the connecting part 4d is thickened more than the outer circumferential part side, and the connecting part 4d is expanded in a direction for separating the protrusion 4e from the cut-off member 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure cut-off sensor, and more particularly to a pressure cut-off sensor used to secure safety when the pressure inside a case whose inside is airtightly shielded rises.

[0002]

2. Description of the Related Art Conventionally, primary batteries and lithium ion secondary batteries which are sealed by injecting an organic solvent-based electrolyte into a battery case, for example, have been widely used as a power source for portable equipment such as telephones and cameras. ing. However, when overcharging or recharging such a battery with a current larger than the specified current, an abnormality occurs in the battery and gas is generated in the battery. When the pressure or temperature rises, the battery expands, and a crack or the like is generated in the battery case, so that the internal electrolytic solution oozes out to adversely affect equipment in which the battery is incorporated. Also,
Even if this does not occur, if the use of the battery is continued in the abnormal state as described above, the battery may expand and the battery case may be ruptured. Had to be discontinued.

For this reason, in the above-described battery, when the internal pressure of the battery rises abnormally, the internal current circuit is interrupted to stop the flow of current, and the pressure at which the internal pressure does not further increase is reduced. An interruption sensor is incorporated. This pressure cut-off sensor includes a cover member having a cut-off member having a conductive path and a diaphragm below the cut-off member, the member being displaceable when the pressure inside the battery becomes equal to or higher than a predetermined value. Was attached by crimping or welding. When an abnormality occurs in the battery using such a conventional pressure cut-off sensor and the pressure in the battery rises, the diaphragm is pushed up to the upper blocking member side to be inverted, and the center of the diaphragm is turned upside down. Press near the center of the blocking member. Then, the pressing load is concentrated on the vicinity of the central portion of the blocking member, and the blocking member is broken from the vicinity of the central portion to cut off the conductive path. When the conductive path is cut off, the flow of current inside the battery is cut off, so that the pressure inside the battery does not increase any more.

[0004]

However, the above-described conventional pressure cut-off sensor is manufactured by joining a member having a diaphragm part, which is a separate member from the lid, to the lid by caulking or welding. It was complicated and costly. Further, in order to make the diaphragm portion easily displaced by a rise in pressure inside the battery, the thickness of the displaced portion is formed to be uniform and thin as a whole. For this reason, the diaphragm portion is easily displaced, but because the entire body is uniform and thin, the pressure rise inside the battery pushes up the diaphragm portion to the blocking member side, and even if the central portion contacts the blocking member, the central portion is crushed. In such a case, the load for breaking the blocking member is dispersed, and the blocking member may not be broken.
In addition, when the diaphragm is crushed, the height of the diaphragm is not stabilized, and the breaking member can be broken even if the internal pressure of the battery rises above a specified value. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-described problems and to surely break a blocking member at low cost.

[0005]

According to a first aspect of the present invention, there is provided a pressure cut-off sensor comprising a case, a cover for hermetically shielding the inside of the case, and a cover for the cover. A diaphragm portion formed partially and displaced when the internal pressure of the case rises above a predetermined value; and a blocking member disposed above the diaphragm portion and having a conductive path, wherein the diaphragm portion includes the lid. And a convex portion protruding in the vicinity of the central portion of the connecting portion toward the blocking member side. The outer peripheral side of the connecting portion is thinned, and the central portion of the connecting portion is thinned. The vicinity is formed to be thicker than the outer peripheral side, and the connecting portion is formed so as to bulge in a direction in which the protruding portion is moved away from the blocking member.

[0006] As a second means for solving the above-mentioned problem, the thickness of the connecting portion is gradually increased from the outer peripheral portion of the connecting portion to the convex portion. .

As a third means for solving the above-mentioned problem, the diaphragm portion has a structure in which a part of the lid is annularly recessed to form the connecting portion.

As a fourth means for solving the above-mentioned problem, a thin connection is provided to a part of a lid which is disposed below a blocking member having a conductive path and hermetically shields the inside of the case. Part, and a diaphragm portion composed of a convex portion protruding near the center of the connecting portion toward the blocking member side,
A step of forming a thin connecting portion by recessing a part of the lid, a step of forming a convex portion by projecting a portion near the center of the connecting portion toward the blocking member, and forming the convex portion. Bulging the connecting portion in a direction away from the blocking member.

According to a fifth aspect of the present invention, in the step of forming the thin connecting portion, the connecting portion is formed in an annular shape, and the outer peripheral side of the connecting portion is thinned. The assembling method was such that the vicinity of the central portion was formed thicker than the outer peripheral portion.

According to a sixth aspect of the present invention, in the step of forming the connecting portion, a part of the lid is recessed by grinding to form a thin portion, and the convex portion is formed. And an assembling method in which the step of forming the protrusion and the step of forming the connection portion are formed by press working, and the step of forming the protrusion and the step of forming the connection portion are formed in a single step at the same time. did.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the pressure cut-off sensor according to the present invention will be described below. FIG. 1 is a sectional front view of a pressure cut-off sensor of the present invention, FIG. 2 is an exploded perspective view of the pressure cut-off sensor of the present invention, and FIG. 3 is a top view and a right side view of a lid used for the pressure cut-off sensor of the present invention. 4 is a sectional front view of the lid, FIG. 5 is a bottom view of the lid, FIGS. 6 and 7 are enlarged sectional views of a safety valve portion of the lid, and FIGS. 8, 9, and 10 are lids used for the pressure cutoff sensor of the present invention. It is a figure explaining a manufacturing method of a diaphragm part.

The pressure cutoff sensor 1 of the present invention is formed in a substantially rectangular shape as a whole, and has a terminal portion 2, an insulator 3, a lid (negative case) 4, a holder 5, an external electrode 6, and a blocking member 7. , Rivets 8, and the like.

The terminal portion 2 is made of aluminum and is bent at a substantially right angle as shown in FIG. 2, and has a connection piece portion 2a welded to a connection portion 8d of the rivet 8 at one end in the longitudinal direction. Is extended. A plurality of substantially circular openings 2c are formed in the flat portion 2b. Insulator 3
Is formed of an insulating resin material, a cylindrical portion 3a through which the rivet 8 is inserted near one end, a concave portion 3b that allows the diaphragm 4c of the lid 4 to bulge inward, and a through hole formed in the bottom surface of the concave portion 3b. The formed ventilation holes 3c, 3c and the welding holes 3
d, a substantially rectangular opening 3e, 3e communicating with the safety valve portion 4d of the lid 4, and a positioning projection 3f.

The lid 4 is formed of a conductive metal plate such as a stainless steel material, and is formed in a substantially rectangular lunch box shape with a substantially rectangular outer shape as shown in FIGS. A flat bottom plate 4a is formed by projecting the inside of the flange 4j downward by drawing or the like. A ridge 4b is formed around the bottom plate 4a to connect the flange 4j and the bottom plate 4a. A hole 4c is formed near the one end of the bottom plate 4a and extends through the cylindrical portion 3a through which the rivet 8 is inserted. A diaphragm D is formed on the right side of the hole 4c in the drawing. This diaphragm part D is a bottom plate 4
a concave portion 4k in which a part of the back surface of the outer peripheral portion is annularly concave.
Is formed, and the bottom surface of the concave portion is formed to be thin to form the connecting portion 4d. A projection 4e is formed near the center of the connecting portion 4d and protrudes toward the blocking member 7 in the upper part of the figure.

The diaphragm portion D is formed by engraving a part of the lower surface side of the lid 4 into an annular shape by grinding or the like.
k is formed. When forming the recess 4k,
The outer peripheral portion side of the connecting portion 4d is formed to be thin, and the vicinity of the convex portion 4e including the convex portion 4e near the central portion of the connecting portion 4d is formed thicker than the thin portion on the outer peripheral portion side. The thickness of the connecting portion 4d in the outer peripheral portion and the vicinity of the central portion is gradually increased from the outer peripheral portion to the central convex portion. The diagram portion D is formed by bulging the connecting portion 4d downward in a bowl shape in a direction in which the central convex portion is moved away from the upper blocking member 7. The convex portion 4e is formed by projecting a central portion of a thickly formed connecting portion 4e upward as shown in FIG. 6 by a press or the like. As shown in FIG. The protrusion may be formed in a state where the material is packed inside.

A safety valve portion Z is formed on a bottom plate 4a near the other end of the lid 4 shown in FIG. The safety valve portion Z is formed on a part of the bottom plate 4a and has an annular outer shape and projects upward in the drawing, and is formed at the root of the projection 4f to connect the lid 4 and the projection 4f. The connecting portion 4g is formed to be thinner than the protruding portion 4f, and the shape of the connecting portion 4g as viewed from above is formed in an annular shape. In such a safety valve portion Z, the projecting direction of the projecting portion 4f is formed so as to project outside a case (not shown) that shields the inside of the battery. The pressure rises abnormally, and the internal pressure of the battery is applied to the protruding portion 4f, so that the thinly formed connecting portion 4g is broken. The high-pressure gas inside the battery is discharged to the outside from the broken portion of the connecting portion 4g. Also,
At the other end of the lid 4, a positioning projection 4 h is formed at a corner of the bottom plate 4 a by projecting a part of the projection 4 b inward, and an outer periphery at the upper end of the projection 4 b. The lid 4 is formed by forming a flange portion 4j extending in the direction.

The holder 5 is formed of an insulating resin material such as PPS, and has a size to be fitted into the ridge 4b of the cover 4 as shown in FIG. Near one end of the holder 5, a through hole 5a penetrating a cylindrical portion through which the rivet 8 is inserted.
And a rivet 8 provided in a recess around the through hole 5a.
And a pair of leads 9b,
9c, openings 5b and 5b respectively extending therefrom, a pedestal 5c for holding the external electrode 6, an electrode connection 9d connected to the connection 6c of the external electrode 6, and a fixing part welded to the lid 4. 9e, an opening 5d formed at a position corresponding to the safety valve portion Z, and a notch 5e into which a positioning projection 4h of the lid 4 is fitted.

The rivet connection part 9a, leads 9b, 9
c, the electrode connecting portion 9d, and the fixing portion 9e are each made of a conductive metal plate or the like, and are integrated with the holder 5 by insert molding. An electrode connecting portion 9 is provided on the lower surface of the holder 5.
A hole 5f exposing the lower surface of the hole d is formed.
f to the electrode connecting portion 9d of the holder 5 through a welding tool,
The welding tool is applied to the connecting portion 6c of the external electrode 6 from above and sandwiched therebetween to perform spot welding, thereby fixing the external electrode 6 to the holder 5 and electrically connecting the external electrode 6 to the lead 9c.

The rivet connection portion 9a and the lead 9b are connected, and the lead 9b is electrically connected to the lead 9c via the blocking member 7 and connected to the external electrode 6. On the other hand, the fixing portion 9e is independent and is not electrically connected to the other. The holder 5 is fixed to the fixing portion 9e and the bottom plate 4a of the lid 4 disposed on the lower surface thereof by spot welding or the like.

The external electrode 6 is formed by plating a metal plate such as an iron plate with nickel, and has a substantially rectangular body 6a and legs 6b and 6 bent from both side edges of the body 6a.
b and the connection part 6 connected to the electrode connection part 9 e of the holder 5
c is provided. The external electrode 6 serves as a positive electrode of the battery when the pressure cutoff sensor 1 is incorporated in the battery (not shown).

The blocking member 7 is made of a brittle insulating material such as ceramics. As shown in FIG. 2, a narrow portion 7a having a substantially band shape and having a width smaller than both ends is formed at the center.
On the upper surface side of the blocking member 7, a conductive path 7b formed by printing a conductive member or forming a metal foil by adhesion or the like is provided. The blocking member 7 is mounted with both ends of wide conductive paths 7b supported at both ends by the leads 9b and 9c of the holder 5 and electrically connected by soldering or the like. Therefore, when pressure is applied to the central narrow portion 7a, the blocking member 7 is broken from the narrow portion 7a, and the conductive path 7b is cut off.

The rivet 8 is made of aluminum, and as shown in FIG. 2, a cylindrical portion 8a having a slightly thinner tip end, a flange 8b provided at the lower end, and an upper portion extending along the outer periphery of the flange 8b. An annular ridge 8c protrudes and a connecting portion 8d protruding laterally from the flange 8b. The connecting piece 8a of the terminal portion 2 is welded to the connecting portion 8d. Has become. Further, the insulator 3, the lid 4, and the holder 5 are integrated by caulking the tip of the cylindrical portion 8a of the rivet 8,
The swaged portion is connected to the rivet connection portion 9a of the holder 5. Therefore, the external electrode 6 is electrically connected to the terminal 2 via the conductive path 7b of the blocking member 7 and the like.

The pressure cutoff sensor 1 of the present invention as described above
Is used for a battery (not shown) composed of, for example, a lithium ion secondary battery or the like. When the pressure cutoff sensor 1 is inserted from above into a case (not shown),
The flange 4j is connected over the entire periphery of the fitting portion of the case by welding or the like, and an electrolyte is injected from an electrolyte injection hole (not shown) provided on the side surface of the case. By closing with, the inside of the case is sealed. In addition, a current path when charging a battery using the pressure cut-off sensor 1 of the present invention is sequentially from the external electrode (positive electrode) 6 through the lead 9c, the conductive path 7b of the blocking member 7, the lead 9b, and the rivet 8. , To the terminal unit 2.

At this time, if overcharging is performed to continue to supply a current even after charging is completed, or if charging is performed with a current larger than a specified current, an abnormality occurs inside the battery (not shown). The pressure and temperature inside the battery rise abnormally.
Then, the increased internal pressure inside the battery is transmitted to the pressure cutoff sensor 1, and the increased internal pressure of the battery is transmitted to the vent hole 3 of the insulator 3.
The transmission is made to the diaphragm part D via c and 3c, and to the safety valve part Z via the openings 3e and 3e. Then, when the pressure inside the battery (not shown) further increases and the internal pressure reaches a predetermined pressure, the diaphragm portion D is turned upward at once from the connecting portion 4d of the thin peripheral portion. This connecting part 4
By the sudden reversal of d, the vicinity of the thick central portion is lifted to the breaking member 7 side, and the thick convex portion 4e is
Of the brittle material that collides with the narrow portion 7a of the
Is applied to the narrow portion 7a, and the blocking member 7 is broken from the narrow portion 7a. Due to the breakage of the blocking member 7, the electrical conduction of the conductive path 7b is interrupted, and the electrical conduction between the leads 9b and 9c is interrupted. By interrupting the electrical conduction between the leads 9b and 9c, the pressure cutoff sensor 1
By interrupting the current flowing between the external electrode 6 and the positive electrode of the power generation unit in the battery and stopping further charging, it is possible to suppress the pressure rise inside the battery and prevent the battery from bursting or the like. It has become.

Even if the breaking of the blocking member 7 causes the flow of current to stop, if the internal pressure of the battery further increases due to the effect of the electrolyte inside the battery, the safety valve Z of the cover 4 will be closed. The thin connecting portion 4g is broken, and the high-pressure gas in the battery is discharged from the battery through the opening 5d to the outside of the battery. For example, the operating pressure of the pressure cut-off sensor 1 of the present invention is such that the diaphragm 4d is operated in reverse at a stroke in the range of 4 to 10 atm.
The connection portion 4g of the safety valve portion Z is set to break and operate within a range of up to 20 atm.

A method of manufacturing the diaphragm D of the pressure cutoff sensor 1 according to the present invention will be described with reference to FIGS. First, the flange 4j of the lid 4 is turned downward, and a part of the lower surface 4m side of the bottom plate 4a is annularly recessed with a grinding wheel J as shown in FIG. At this time, the shape of the connecting portion 4e is a substantially triangular pyramid in which the outer peripheral portion side of the annular shape is formed to be thin and gradually thicker from the outer peripheral portion to the central portion.

Next, there is a mold K for forming the diaphragm portion D as shown in FIG. 9, and this mold K is an upper mold K1.
And a lower mold K5. The upper die K1 is cylindrical and has a flat portion K2, a protruding portion K3 for bulging the connecting portion 4d, and a protruding portion 4e of the diaphragm portion D at the center of the protruding portion K3 at the lower end in the figure. Recess K for forming
4 are formed. Further, a lower mold K5 is disposed below the upper mold K1 opposite to the lower mold K1. A flat section K6 is formed in a portion of the lower mold K4 corresponding to the flat section K2 of the upper mold K1, and a protrusion K3 of the upper mold K1 is formed. And a bowl-shaped portion K7 for forming the connecting portion 4d in a bowl-like shape at a portion corresponding to the recessed portion K4 of the upper die K1.
A protrusion forming portion K8 is formed so as to protrude at a portion corresponding to.

The mold K having such a configuration is mounted on a press or the like, and the lid 4 having the annular concave portion 4k formed on the lower mold K5 is placed with the flange 4j facing upward. At this time, the lid 4 is positioned such that a part of the flange 4j is positioned by a pilot pin (not shown) or the like, and the lower die K is inserted into the recess 4k of the bottom plate 4a.
5 flat portion K6 enters. The upper die K1 is lowered downward to the lid 4 positioned on the lower die K5 as described above, and the upper die K1 and the lower die k5 sandwich the connection part 4d ground in a substantially conical shape, and this connection is made. The part is plastically deformed. When the upper die K1 moves to the bottom dead center of the press, FIG.
As shown in (5), the concave portion K4 of the upper die K1 and the convex portion forming portion K8 of the lower die K5 form a convex portion 4e that protrudes upward near the center of the connecting portion 4d. Also, the protrusion K3 of the upper die K1
The connecting portion 4d is formed to bulge downward from the lower portion K5 and the bowl-shaped portion K7 of the lower mold K5, and the diaphragm portion D is completed.

That is, according to the method of manufacturing the pressure cut-off sensor of the present invention, a step of forming a thin connecting portion 4d by grinding a part of the lower surface 4m of the lid 4 by grinding, and the vicinity of the center of the connecting portion 4d To form a convex portion 4e by projecting the convex portion 4e toward the blocking member 7 side, and a process of bulging the connecting portion 4d in a direction in which the convex portion 4e is moved away from the blocking member 7. In the diaphragm D, the step of forming the convex portion and the step of forming the connecting portion 4d by bulging are simultaneously performed in one step by press working.

The connecting portion 4d of the diaphragm portion D formed by such a manufacturing method is formed in such a manner that the outer peripheral side formed in an annular shape is formed to be thin and the central portion is formed to be thick. Even if the internal pressure of a battery (not shown) incorporating the pressure cut-off sensor of the present invention abnormally rises, the diaphragm portion D
As a result, the flow of the current inside the battery can be instantaneously interrupted, and the rupture of the battery can be prevented. In the method of manufacturing the pressure cut-off sensor according to the present invention, the method of forming the convex portion 4e of the diaphragm portion D and the process of forming the connecting portion 4d by bulging have been described as a method of simultaneously forming one step. However, each of the above steps may be divided into two steps. Also, the method of forming the connecting portion of the diaphragm portion of the pressure cut-off sensor of the present invention has been described by a method in which a part of the lid is formed by recessing the lid by grinding, but a part of the lid is crushed by pressing or the like. May be used.

[0031]

The pressure cutoff sensor according to the present invention has a cutoff member having a conductive path, and the diaphragm has a connecting portion in which a part of the lid is made thin, and the vicinity of the center of the connecting portion is close to the cutoff member. A direction in which the outer peripheral portion side of the connecting portion is formed thinner and the vicinity of the central portion of the connecting portion is formed thicker than the outer peripheral portion, and the convex portion is moved away from the blocking member. Since the connecting portion is formed to bulge, when the thin connecting portion on the outer peripheral portion is displaced and the convex portion is lifted to the blocking member side,
The blocking member can be easily broken at the convex portion near the center formed in a thick wall, and a highly safe pressure-blocking sensor can be provided.

Further, since the thickness of the connecting portion is gradually increased from the outer peripheral portion of the connecting portion to the convex portion, it is ensured that the protruding connecting portion is surely turned upward at a stretch. Thus, the upper blocking member can be reliably broken.

Further, since the diaphragm portion has the connecting portion formed by depressing a part of the lid in an annular shape, the internal pressure of the battery can be evenly applied to the annular connecting portion, and the accuracy is further improved. Thus, it is possible to provide a high-quality pressure cut-off sensor. Further, since a part of the lid is concavely formed in an annular shape, a connecting portion of the diaphragm unit integral with the lid can be easily formed by grinding or the like, and a low-cost pressure cut-off sensor can be provided. it can.

Further, according to the method of manufacturing a pressure cutoff sensor of the present invention, a thin connecting portion is provided on a part of a lid which is disposed below a blocking member having a conductive path and hermetically shields the inside of the case. A step of forming a thin-walled connecting portion by depressing a part of the lid to form a diaphragm portion comprising a convex portion protruding near the center of the connecting portion toward the blocking member;
A step of forming the convex portion by projecting the vicinity of the central portion of the connecting portion toward the blocking member, and a step of bulging the connecting portion in a direction away from the blocking member. Therefore, the diaphragm can be formed integrally with the lid, and a low-cost, high-quality pressure cutoff sensor can be provided.

In the step of forming a thin connecting portion, the connecting portion is formed in an annular shape, and the outer peripheral side of the connecting portion is formed thinner and the central portion is formed thicker than the outer peripheral portion.
When the internal pressure becomes high, the displacement is ensured, and the upper blocking member can be reliably broken.

In the step of forming the connecting portion, a part of the lid is concavely formed by grinding to form a thin wall, and the step of forming the convex portion and the step of bulging the connecting portion are performed by pressing. Since the step of forming the convex portion and the step of bulging and forming the connecting portion are performed simultaneously in one step, the manufacturing process of the pressure cut-off sensor of the present invention can be shortened. A low-cost pressure cut-off sensor can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional front view of a main part of a pressure cut-off sensor according to the present invention.

FIG. 2 is an exploded perspective view of the pressure cutoff sensor of the present invention.

3A and 3B are a top view and a right side view of a lid used for the pressure cutoff sensor of the present invention.

FIG. 4 is a sectional front view of a lid used for the pressure cut-off sensor of the present invention.

FIG. 5 is a bottom view of a lid used for the pressure cut-off sensor of the present invention.

FIG. 6 is an enlarged sectional view of a diaphragm portion of a lid used in the pressure cutoff sensor of the present invention.

FIG. 7 is an enlarged sectional view of a diaphragm portion of a lid used for the pressure cut-off sensor of the present invention.

FIG. 8 is a schematic diagram illustrating a method for manufacturing a diaphragm portion of a lid used for the pressure cut-off sensor of the present invention.

FIG. 9 is a schematic diagram illustrating a method for manufacturing a diaphragm portion of a lid used for the pressure cut-off sensor of the present invention.

FIG. 10 is a schematic diagram illustrating a method for manufacturing a diaphragm portion of a lid used for the pressure cut-off sensor of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pressure cut-off sensor 2 Terminal part 2a Connection piece part 2b Flat part 2c Opening part 3 Insulator 3a Cylindrical part 3b Concave part 3c Vent 3d hole 3e Opening 4 Lid 4a Bottom plate 4b Protrusion 4c Hole D Diaphragm part 4d Connection part 4e Projection 4f Projection 4g Connection 4h Projection 4j Flange 5 Holder 5a Through-hole 5b Opening 5c Pedestal 5d Opening 5e Notch 5f Hole 6 External electrode 6a Body 6b Leg 6c Connection 7 Element 7a Narrow section 7b Blocking circuit 8 Rivet 8a Column section 8b Flange section 8c Annular ridge 8d Connection section 9a Riveting connection section 9b Lead 9c Lead 9d Electrode connection section 9e Fixing section K Mold K1 Upper mold K2 Flat section K3 projecting part K4 concave part K5 lower die K6 flat part K7 bowl-shaped part K8 convex part forming part

Claims (6)

[Claims] 1. A case, a lid for hermetically shielding the inside of the case, a diaphragm formed on a part of the lid and displaced when the internal pressure of the case rises above a predetermined value, and a diaphragm for the case And a blocking member disposed above the portion and having a conductive path, wherein the diaphragm portion has a connecting portion in which a part of the lid is thinned, and a portion near the center of the connecting portion protrudes toward the blocking member. And the outer peripheral side of the connecting portion is formed thinner near the center of the connecting portion than the outer peripheral portion, and the convex portion is moved away from the blocking member in a direction away from the blocking member. A pressure cut-off sensor, characterized in that the connecting portion is formed to bulge. 2. The pressure cut-off sensor according to claim 1, wherein a thickness of the connecting portion is gradually increased from an outer peripheral portion of the connecting portion to the convex portion. 3. The pressure cut-off sensor according to claim 1, wherein the diaphragm portion has the connecting portion formed by depressing a part of the lid in an annular shape. 4. A thin connecting portion provided on a part of a lid which is disposed below a blocking member having a conductive path and hermetically shields the inside of the case, and a portion near the center of the connecting portion is the blocking member. The diaphragm part consisting of the convex part protruded to the side,
A step of forming a thin connecting portion by recessing a part of the lid, a step of forming a convex portion by projecting a portion near the center of the connecting portion toward the blocking member, and forming the convex portion. Swelling the connecting portion in a direction away from the blocking member. 5. In the step of forming the thin connecting portion, the connecting portion is formed in an annular shape, the outer peripheral side of the connecting portion is formed thinner, and the central portion is formed thicker than the outer peripheral portion. The method for manufacturing a pressure cut-off sensor according to claim 4, wherein 6. The step of forming the connecting portion includes a step of forming a thin portion by recessing a part of the lid by grinding, and a step of forming the convex portion and a step of bulging the connecting portion. The pressure cut-off sensor according to claim 4, wherein the step of forming the convex portion and the step of bulging and forming the connecting portion are simultaneously performed in one step by press working. Production method.