JP2000182491A - Differentially spotting type heat sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the accuracy in detecting fires from going out of order, depending on whether ambient temperature is high or low. SOLUTION: This differentially spotting type heat sensor includes a metallic heat sensing casing 1 which is surrounded by a heat sensing plate 10, a diaphragm 11, and a diaphragm supporting plate 12, a body 2 made of a synthetic resin for binding the peripheral edge of the heat-sensing casing 1, a movable electrode moved by the displacement of a diaphragm resulting from the expansion of air in the heat-sensing casing 1 caused by the rise in ambient temperature, and a fixed electrode provided in the body, the movable electrode which moves towards and away from the fixed electrode. A reinforcing rib 22 is provided on the side of the body facing opposite the heat sensing casing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a differential spot-type heat sensing device in which a fire is detected by expanding the air inside a heat-sensitive box and causing a displacement of a diaphragm constituting the heat-sensitive box. About the vessel.

[0002]

2. Description of the Related Art A conventional technique will be described with reference to FIGS. FIG. 8 is a cross-sectional side view showing a differential spot-type heat sensor, and FIG. 9 is an enlarged cross-sectional side view of a main part of the differential spot-type heat sensor. 10A and 10B are schematic cross-sectional views illustrating how the alert accuracy of the differential spot-type heat sensor changes depending on the ambient temperature. FIG. 10A illustrates a case where the ambient temperature is high, and FIG. The cases where the ambient temperature is low are shown.

[0003] The differential spot-type heat sensor detects a rise in the ambient temperature due to a fire and detects the occurrence of the fire. Can be The differential spot type heat sensor is shown in FIG.
As shown in the figure, the heat-sensitive box 1, the body 2, and the movable electrode 3
And the fixed electrode 4.

The heat-sensitive box 1 comprises a heat-sensitive plate 10 and a diaphragm 1 made of a metal such as stainless steel which is resistant to rust.
1 and a diaphragm support plate 12. The heat-sensitive plate 10 is formed by drawing a metal plate into a substantially bowl shape. The diaphragm 11 is made of a substantially circular metal foil, and its central portion is adapted to generate a displacement corresponding to a change in the internal pressure in the heat-sensitive box 1. The diaphragm support plate 12 is an annular sheet metal processing member having a substantially L-shaped cross section for supporting the diaphragm 11. The diaphragm support plate 12 does not cause a displacement of the diaphragm 11 when there is no change in the ambient temperature, but causes a displacement in accordance with the change rate of the ambient temperature when a change occurs in the ambient temperature.
Extremely minute air holes 12a are provided.

The outer peripheral edge of the diaphragm 11 is hermetically joined to the inner peripheral edge of the diaphragm support plate 12 over the entire periphery. Further, the outer peripheral edge of the diaphragm support plate 12 is hermetically joined to the peripheral edge of the heat sensitive plate 10 over the entire periphery. In other words, the heat-sensitive box 1 is airtight except for the ventilation holes 12a, and the inner pressure and the outer pressure of the heat-sensitive box 1 are equally balanced in a state where there is no change in the ambient temperature. Occurs, a pressure difference corresponding to the rate of change of the ambient temperature is generated. Then, the diaphragm 11 generates a displacement corresponding to the change rate of the ambient temperature.

The body 2 is a substantially disk-shaped member formed of a synthetic resin such as ABS resin, and covers the diaphragm 11 and the diaphragm support plate 12 so as to cover the heat-sensitive box 1.
Detain the perimeter. Specifically, as shown in FIG.
After the outer peripheral edge of the diaphragm support plate 12 of the heat-sensitive box 1 is fitted into the circular concave portion 20 on the lower surface of the body 2, a fixing rib 21 made of synthetic resin is ultrasonically welded to the peripheral edge of the concave portion 20 to thereby form the heat-sensitive box The periphery of the body 1 is firmly held by the body 2.

The movable electrode 3 is formed of a strip-shaped metal plate which is conductive and has a spring property. One end of the movable electrode 3 is bent at a substantially right angle, is connected to the connection terminal 2a, and is implanted in the body 2. The other end is lightly in contact with the central portion of the diaphragm 11, and a contact portion 3a is provided on a surface of the other end not in contact with the diaphragm 11.

The fixed electrode 4 is made of a conductive and strip-shaped metal plate. One end of the fixed electrode 4 is bent at a right angle, connected to the connection terminal 2b and implanted in the body 2, and the other end is connected to the contact portion 3.
a, and a contact 4a is provided at the other end at a position facing the contact 3a.

[0009] The differential spot type heat sensor constructed as described above operates as follows. That is, when there is no change in the ambient temperature, the internal pressure and the external pressure of the heat-sensitive box 1 are balanced by the flow of air through the ventilation holes 12a, and the displacement of the diaphragm 11 does not occur. However, when the ambient temperature rises due to a fire or the like, the air in the heat-sensitive box 1 also rises in temperature through the heat-sensitive plate 10 and expands, and a part of the expanding air leaks through the vent hole 12a. When the ambient temperature rise rate is high, the amount of leakage with respect to the amount of air that expands cannot catch up, the internal pressure of the heat-sensitive box 1 rises, the diaphragm 11 expands and displaces, and the contact portion 3a of the movable electrode 3 Push up.

Therefore, when the ambient temperature changes relatively moderately, such as day and night or seasonal changes in the ambient temperature,
Although the contact portion 3a and the contact portion 4a do not come into contact with each other, if the surrounding temperature rises rapidly due to a fire or the like, the contact portion 3a and the contact portion 4a come into contact with each other and the connection terminal 2
a and the connection terminal 2b are electrically short-circuited, and the occurrence of a fire can be detected.

[0011]

However, in the conventional differential spot-type heat sensor, the peripheral edge of the metallic heat-sensitive box 1 is firmly fixed in the vicinity of the peripheral edge of the synthetic resin body 2. Is held. The heat-sensitive box 1 is made of metal, is robust and has a small coefficient of thermal expansion. On the other hand, the body 2 is made of a synthetic resin, is relatively soft, and has a large coefficient of thermal expansion.
Therefore, when the ambient temperature becomes low or high, the body 2 made of synthetic resin bends due to the difference in the coefficient of thermal expansion.

For example, when the ambient temperature is high, the body 2 tends to expand as a whole, but the body 2 is integrated with the heat-sensitive box 1 in the portion where the heat-sensitive box 1 is held. As a result, as shown in FIG. 10A, the body 2 is deformed in a state in which the central portion is raised upward. On the other hand, when the ambient temperature is low, the body 2 tends to shrink as a whole, but shrinks in the portion where the heat-sensitive box 1 is held because the body 2 is integrated with the heat-sensitive box 1. As a result, as shown in FIG. 10 (b), the body 2 is deformed so that the central portion hangs down. In FIG. 10, the deformation of the body 2 is emphasized.

Therefore, depending on the level of the ambient temperature, usually 4
The gap between the contact portion 3a and the contact portion 4a of about 00 micron changes slightly, and the fire detection accuracy changes,
Contact point 3a and contact point 4a do not come into contact with each other in spite of fire, or contact point 3a and contact point 4a come in contact with each other even if it is not a fire. There was a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an excellent differential spot-type heat sensor which does not cause a change in fire detection accuracy due to a change in ambient temperature. Is to provide.

[0015]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a metal heat-sensitive box surrounded by a heat-sensitive plate, a diaphragm and a diaphragm support plate, and a peripheral portion of the heat-sensitive box. A body made of synthetic resin to be held, a movable electrode operated by displacement of a diaphragm due to air expansion in the heat-sensitive box due to an increase in ambient temperature, and a fixed electrode provided on the body and to which the movable electrode comes into contact with or separates from. In the differential spot type heat sensor, a reinforcing rib is provided on a surface of the body facing the heat-sensitive box. Further, it is preferable that the reinforcing ribs are provided substantially in a radial shape. Further, it is preferable that a portion of the reinforcing rib facing the diaphragm supporting plate is provided at a height at which the reinforcing rib comes into contact with the diaphragm supporting plate.

Also, a metal heat-sensitive box surrounded by a heat-sensitive plate, a diaphragm and a diaphragm support plate, a synthetic resin body that holds a peripheral portion of the heat-sensitive box, and a heat-sensitive body caused by an increase in ambient temperature. In a differential spot-type heat sensor including a movable electrode that operates by displacement of a diaphragm caused by air expansion in a box body, and a fixed electrode that is provided on the body and to which the movable electrode comes and goes, a contact is made with the diaphragm support plate. An abutting rib is provided on the side of the body facing the heat-sensitive box so as to substantially surround the diaphragm.

Also, a metal heat-sensitive box surrounded by a heat-sensitive plate, a diaphragm and a diaphragm support plate, a synthetic resin body for holding a peripheral portion of the heat-sensitive box, and a heat-sensitive body due to an increase in ambient temperature. In a differential spot-type heat sensor including a movable electrode operated by displacement of a diaphragm caused by air expansion in a box, and a fixed electrode provided on the body and to which the movable electrode comes and goes, a heat-sensitive box of the body A metal ring is provided along the vicinity of the peripheral edge on the side opposite to the facing surface.

Further, a metal heat-sensitive box surrounded by a heat-sensitive plate, a diaphragm and a diaphragm support plate, and a heat-sensitive box holding portion for holding the heat-sensitive box by holding a peripheral portion of the heat-sensitive box. A differential comprising: a synthetic resin body having a movable electrode operated by displacement of a diaphragm caused by air expansion in a heat-sensitive box due to an increase in ambient temperature; and a fixed electrode provided in the body and to which the movable electrode comes and comes. In the spot type heat sensor, a flange portion is provided on a peripheral portion of the heat-sensitive box, a fitting portion is provided on the body so that the flange portion can be loosely fitted, and the flange portion is loosely fitted on the fitting portion. Along with
A shock-absorbing member for pressing the heat-sensitive box against the body is interposed between the flange-shaped portion and the heat-sensitive box holding portion.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of a differential spot type heat sensor according to the present invention will be described with reference to FIGS. 1 and 2, and a second embodiment will be described with reference to FIGS. 4, a third embodiment will be described in detail with reference to FIGS. 5 and 6, and a fourth embodiment will be described in detail with reference to FIG.

[First Embodiment] FIG. 1 is a sectional side view showing a differential spot-type heat sensor, and FIG. 2 is a front view showing a body of the differential spot-type heat sensor. 1 and 2, the same reference numerals are given to the same parts as those of the differential spot-type heat sensor described with reference to FIGS. 8 to 10 in the related art.

The feature of this differential spot type heat sensor is different from that of the conventional type in that a reinforcing rib 22 is provided on the lower surface of the body 2, that is, the surface facing the heat-sensitive box 1. As shown in FIG. 2, the reinforcing ribs 22 are formed substantially radially from the center of the lower surface of the body 2 so as to avoid the fixed electrode 4 and the movable electrode 3.

In the differential spot-type heat sensor configured as described above, the ambient temperature changes depending on day and night or season, and the temperature of the entire differential spot-type heat sensor becomes high or low. Even if the metal heat-sensitive box 1 or the synthetic resin body 2 undergoes expansion and contraction due to the coefficient of thermal expansion according to each material, the presence of the reinforcing ribs 22 makes the body 2 less likely to bend. The change in the gap between the contact part 3a and the contact part 4a can be reduced, the fire detection accuracy is stabilized, and the contact part of the movable electrode 3 and the contact part of the fixed electrode 4 are in contact with each other despite a fire. It is possible to prevent unreported or erroneous reports that the contacts of the movable electrode 3 and the contacts of the fixed electrode 4 come into contact with each other even when the fire is not caused.

[Second Embodiment] FIG. 3 is a sectional side view showing a differential spot type heat sensor, and FIG. 4 is a front view showing a body of the differential spot type heat sensor. In FIGS. 3 and 4, the same reference numerals are given to the same parts as those of the differential spot-type heat sensor described with reference to FIGS.

This differential spot type heat sensor is different from the conventional type in that the reinforcing rib 22 and the contact rib 23 are provided on the lower surface of the body 2, that is, the surface facing the heat-sensitive box 1.
Is provided. As shown in FIG. 4, the reinforcing ribs 22 are formed substantially radially from the center of the lower surface of the body 2 so as to avoid the fixed electrode 4 and the movable electrode 3. The contact rib 23 is formed in a substantially circular shape centered on the center of the lower surface of the body 2 as shown in FIG. The contact ribs 23 are higher than the reinforcing ribs 22, and when the peripheral edge of the heat-sensitive box 1 is held on the peripheral edge of the lower surface of the body 2, the top of the contact rib 23 just supports the diaphragm of the heat-sensitive box 1. It is configured to abut the plate 12.

In the differential spot-type heat sensor configured as described above, the ambient temperature changes depending on day and night or season, and the temperature of the entire differential spot-type heat sensor becomes high or low. Even if the metal heat-sensitive box 1 or the synthetic resin body 2 undergoes expansion and contraction due to the coefficient of thermal expansion according to each material, the presence of the reinforcing ribs 22 makes the body 2 less likely to bend. Since the contact ribs 23 are present in contact with the diaphragm support plate 12 forming the robust heat-sensitive box 1, the ambient temperature becomes low, and in particular, FIG.
As shown in (1), it is possible to prevent the central portion of the body 2 from bending so as to hang down, and to reduce the change in the gap between the contact portion of the movable electrode 3 and the contact portion of the fixed electrode 4. It is possible to stabilize the accuracy of fire detection and to prevent the contact of the movable electrode 3 from contacting the contact of the fixed electrode 4 despite a fire,
The contact portion of the fixed electrode 4 and the contact portion of the fixed electrode 4 can be prevented from being in contact or unreported or misreported.

In the differential spot type heat sensor of this embodiment, the contact rib 2 is provided separately from the reinforcing rib 22.
3 are provided, but the reinforcing ribs 2 are provided without the contact ribs 23.
Even if the portion facing the second diaphragm support plate 12 is brought into contact with the diaphragm support plate 12, the same effect can be obtained. In addition, as a matter of course, the contact rib 23 is provided, and the diaphragm support plate 1 of the reinforcing rib 22 is provided.
Needless to say, the portion facing 2 may have a height that abuts against the diaphragm support plate 12.

[Third Embodiment] FIG. 5 is a sectional side view showing a differential spot type heat sensor, and FIG. 6 is a rear view showing a body of the differential spot type heat sensor. 5 and 6, the same reference numerals are given to the same parts as those of the differential spot type heat sensor described with reference to FIGS. 8 to 10 in the related art.

This differential type spot type heat sensor is different from the conventional type in that it has a feature that the rear surface of the body 2 is provided along the peripheral portion of the side of the body opposite to the surface facing the heat sensitive box. That is, a metal ring 5 made of the same material as the metal material constituting the heat-sensitive box 1 is implanted, buried or fitted. In the differential spot type heat sensor shown in FIGS. 5 and 6, an example is shown in which the metal ring 5 is fitted around the periphery of the concave portion 23 provided on the back surface of the body 2.

In the differential spot-type heat sensor configured as described above, the ambient temperature changes depending on day and night or season, and the temperature of the entire differential spot-type heat sensor becomes high or low. Even if the metal heat-sensitive box 1 or the synthetic resin body 2 undergoes expansion and contraction due to the coefficient of thermal expansion according to each material, the metal heat-sensitive box 1 has the same thermal expansion coefficient as the heat-sensitive box 1 and is made of a robust metal. Due to the presence of the ring 5, the expansion and contraction of the synthetic resin body 2 is suppressed to the same extent as that of the heat-sensitive box 1, and the body 2 is hardly bent.

In the differential spot type heat sensor shown in FIGS. 5 and 6, the metal ring 5 is fitted around the periphery of the concave portion 23 provided on the back surface of the body 2. As shown in FIG. 10B, it is possible to prevent the central portion of the body 2 from sagging downward so that the ambient temperature becomes low, and the contact portion of the movable electrode 3 and the fixed electrode 4 can be prevented. The change of the gap with the contact part of the above can be reduced, the fire detection accuracy is stabilized, and the contact part of the movable electrode 3 and the contact part of the fixed electrode 4 do not come into contact despite fire, It is possible to prevent the contact portion of the movable electrode 3 and the contact portion of the fixed electrode 4 from contacting each other without a fire, and to prevent unreported or false reports.

When the metal ring 5 is implanted or buried in the vicinity of the peripheral edge of the rear surface of the body 2, the case where the metal ring 5 is fitted into the peripheral edge of the concave portion 23 provided on the rear surface of the body 2 is referred to. In contrast, the ambient temperature becomes
As shown in FIG. 10A, it is possible to prevent the central portion of the body 2 from being bent so as to be raised, and to reduce the ambient temperature to a lower portion as shown in FIG. 10B. Can be prevented from sagging downward, the change in the gap between the contact portion of the movable electrode 3 and the contact portion of the fixed electrode 4 can be reduced, and the fire detection accuracy can be stabilized. The contact portion of the movable electrode 3 does not come into contact with the contact portion of the fixed electrode 4 in spite of a fire, or the contact portion of the movable electrode 3 and the fixed electrode 4
And a false report or a false report, in which the contact portion contacts the contact portion, can be prevented.

[Fourth Embodiment] FIG. 7 is an enlarged sectional side view of a main part of a differential spot type heat sensor. In FIG. 7, the same reference numerals are given to the same parts as those of the differential spot type heat sensor described with reference to FIGS. 8 to 10 in the related art.

The feature of this differential spot-type heat sensor, which is different from the conventional one, is that a flange-shaped portion 1a is provided on the periphery of the heat-sensitive box 1 and a circular fitting portion on the lower surface of the body 2 is provided. An O-ring made of a soft and elastic sponge rubber or the like corresponding to a buffering and pressing member, after the corresponding recess 20 is formed with a margin enough to allow the flange 1a to be loosely fitted, and after the flange 1a is loosely fitted into the recess 20. 6, a fixing rib 21 corresponding to a heat-sensitive box holding part made of synthetic resin is provided on the periphery of the concave portion 20 by ultrasonic waves so that the flange-shaped portion 1a of the heat-sensitive box 1 is lightly abutted on the lower surface of the body 2. It is configured to be attached by an adhesive means such as welding.

The O-ring 6 presses the flange portion 1a of the heat-sensitive box 1 lightly against the surface of the concave portion 20 of the synthetic resin body 2 to make contact therewith. In the case where a sliding force due to a difference in the thermal expansion coefficient depending on each material acts, the sliding can be performed immediately.

In the differential spot type heat sensor configured as described above, the ambient temperature changes depending on day and night or season, and the entire differential spot type heat sensor becomes high or low temperature. Even if the metal heat-sensitive box 1 or the synthetic resin body 2 expands and contracts due to the coefficient of thermal expansion according to each material, the synthetic resin body 2 has a small thermal expansion coefficient and is robust. Since the expansion and contraction can be performed almost freely independently of the heat-sensitive box 1, the body 2 is hardly bent.

That is, the contact portion of the movable electrode 3 and the fixed electrode 4
The change in the gap with the contact point of
The fire detection accuracy is stabilized, and the contact portion of the movable electrode 3 and the contact portion of the fixed electrode 4 do not come into contact with each other in spite of a fire, or the contact portion of the movable electrode 3 and the fixed electrode 4 do not have a fire. And a false report or a false report, in which the contact portion contacts the contact portion, can be prevented.

[0037]

According to the first aspect of the present invention, it is possible to prevent the body from being bent due to the difference in the thermal expansion coefficient between the metal heat-sensitive box and the synthetic resin body due to the level of the ambient temperature. The change in the gap between the movable electrode and the fixed electrode can be reduced, the fire detection accuracy can be stabilized, and the movable electrode and the fixed electrode do not come into contact with each other in spite of a fire. It is possible to provide an excellent differential spot-type heat sensor capable of preventing a movable electrode and a fixed electrode from contacting each other, and preventing unreporting and false reporting.

According to the second or third aspect of the present invention, in addition to the effect of the first aspect of the present invention, it is possible to provide an excellent differential spot-type heat sensor which can enable effective reinforcement. To play.

According to the invention as set forth in claims 4 to 6, it is possible to prevent the body from being bent by the difference in the coefficient of thermal expansion between the metal heat-sensitive box and the synthetic resin body due to the level of the ambient temperature. The change in the gap between the movable electrode and the fixed electrode can be reduced, the fire detection accuracy can be stabilized, and the movable electrode and the fixed electrode do not come into contact with each other in spite of a fire. It is possible to provide an excellent differential spot-type heat sensor capable of preventing a movable electrode and a fixed electrode from contacting each other, and preventing unreporting and false reporting.

[Brief description of the drawings]

FIG. 1 is a sectional side view showing a differential spot type heat sensor according to a first embodiment of the present invention.

FIG. 2 is a front view showing a body of the differential spot type heat sensor.

FIG. 3 is a sectional side view showing a differential spot type heat sensor according to a second embodiment of the present invention.

FIG. 4 is a front view showing a body of the differential spot-type heat sensor.

FIG. 5 is a sectional side view showing a differential spot-type heat sensor according to a third embodiment of the present invention.

FIG. 6 is a rear view showing the body of the differential spot type heat sensor.

FIG. 7 is an enlarged sectional side view of a main part of a differential spot-type heat sensor according to a fourth embodiment of the present invention.

FIG. 8 is a sectional side view showing a conventional differential spot-type heat sensor.

FIG. 9 is an enlarged sectional side view of a main part of the differential spot type heat sensor.

FIG. 10 is a schematic cross-sectional view illustrating a manner in which the reporting accuracy of the differential spot-type heat sensor changes depending on the ambient temperature.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 heat-sensitive box 1 a flange portion 10 heat-sensitive plate 11 diaphragm 12 diaphragm support plate 2 body 20 fitting portion 21 heat-sensitive box holder 22 reinforcing rib 23 contact rib 3 movable electrode 4 fixed electrode 5 metal ring 6 buffering and pressing member

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5C085 AA01 AB01 AC07 BA05 CA08 FA13 5G041 AA02 BB07 CB05 CB13 CC03 CD03 CD10 5G405 AA01 AB01 AC01 CA09 FA07

Claims (6)

[Claims] 1. A metal heat-sensitive box surrounded by a heat-sensitive plate, a diaphragm, and a diaphragm support plate; a synthetic resin body that holds a peripheral portion of the heat-sensitive box; In a differential spot-type heat sensor including a movable electrode that operates by displacement of a diaphragm caused by air expansion in a box body and a fixed electrode provided on the body and to which the movable electrode comes and goes, the heat-sensitive box of the body A differential spot-type heat sensor, wherein a reinforcing rib is provided on a body facing surface side. 2. The differential spot-type heat sensor according to claim 1, wherein the reinforcing ribs are provided substantially in a radial shape. 3. The differential spot-type heat sensor according to claim 1, wherein the reinforcing rib has a portion facing the diaphragm support plate at a height at which the reinforcing rib comes into contact with the diaphragm support plate. 4. A metal heat-sensitive box surrounded by a heat-sensitive plate, a diaphragm, and a diaphragm support plate, a synthetic resin body that holds a peripheral portion of the heat-sensitive box, and heat sensitivity caused by an increase in ambient temperature. In a differential spot-type heat sensor including a movable electrode that operates by displacement of a diaphragm caused by air expansion in a box body, and a fixed electrode that is provided on the body and to which the movable electrode comes and goes, a contact is made with the diaphragm support plate. A differential spot type heat sensor, wherein a contacting rib is provided on the side of the body facing the heat-sensitive box so as to substantially surround the diaphragm. 5. A metal heat-sensitive box surrounded by a heat-sensitive plate, a diaphragm, and a diaphragm support plate, a synthetic resin body that holds a peripheral portion of the heat-sensitive box, and heat generated by an increase in ambient temperature. In a differential spot-type heat sensor including a movable electrode operated by displacement of a diaphragm caused by air expansion in a box, and a fixed electrode provided on the body and to which the movable electrode comes and goes, a heat-sensitive box of the body A differential spot-type heat sensor, wherein a metal ring is provided along a portion near a peripheral edge on a side opposite to the opposing surface. 6. A metal heat-sensitive box surrounded by a heat-sensitive plate, a diaphragm and a diaphragm support plate, and a heat-sensitive box holding part for holding the heat-sensitive box by holding a peripheral portion of the heat-sensitive box. A differential comprising: a synthetic resin body having a movable electrode operated by displacement of a diaphragm caused by air expansion in a heat-sensitive box due to an increase in ambient temperature; and a fixed electrode provided in the body and to which the movable electrode comes and comes. In the spot type heat sensor, a flange portion is provided on a peripheral portion of the heat-sensitive box, a fitting portion is provided on the body so that the flange portion can be loosely fitted, and the flange portion is loosely fitted on the fitting portion. A differential spot-type heat sensor, wherein a shock-absorbing member for pressing the heat-sensitive box against the body is interposed between the flange portion and the heat-sensitive box holding portion.