JP2019008720A - Heat sensor - Google Patents

Abstract

To provide a heat sensor capable of adjusting a suitable sensing sensibility as a differential sensor without requiring a power by using a thermoelement.SOLUTION: In a heat sensor 10, a heat medium 16 is arranged so as to be contacted to a cooling surface of a thermoelement 14 arranged so as to exposure a heat receiving surface of a sensor housing 12, a heat exchange amount is adjusted by changing a contact area of the heat medium 16 for the thermoelement 14 by the movement of the heat medium 16 with an adjustment screw 20, a fire detection part detects fire on the basis of a generated voltage corresponding to a temperature difference of the heat receiving surface of the thermoelement 14 and the cooling surface. When performing an operation test and a non-operation test in a manufacturing step, the heat exchange amount is adjusted by changing the contact region of the heat medium 16 for the thermoelement 14 by the adjustment screw 20, and an electric power generation amount is controlled by adjusting the time-variant change of the temperature difference of the thermoelement 14, and a sensing sensibility is optimally adjusted so as to satisfy a differential test and the non-operation test.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a heat detector that detects a fire without using a power source by using a thermoelectric element.

  Conventionally, a differential heat sensor using a diaphragm is known as a heat sensor for detecting a fire without requiring a power source.

  A differential heat sensor using a diaphragm is provided with a pressure-sensitive chamber as a container having an internal space of a predetermined capacity, and a diaphragm made of a thin elastic metal plate is attached to a part of the pressure-sensitive chamber. In addition, a leak hole is provided so that air can enter and exit between the pressure sensitive chamber and the outside through the leak hole. In the event of a fire, as the temperature around the sensor suddenly rises, the air in the pressure-sensitive chamber expands more rapidly than it leaks from the leak hole, and the contact is closed by pushing up the diaphragm. To the receiver (Patent Documents 1 and 2).

  However, since the differential heat sensor involves mechanical operation, fine adjustment is required during production, and since a pressure-sensitive chamber using a diaphragm is provided, a large arrangement space is required in the housing. Therefore, it has been difficult to improve the design by making the heat sensor thinner.

  On the other hand, fire alarms using thermoelectric elements known as Peltier elements are known as fire alarms that detect and alarm fires without requiring a power source (Patent Documents 3 to 5).

  This fire alarm, for example, exposes the heat receiving surface of the thermoelectric element to the outside and makes the metal substrate contact the cooling surface on the opposite side of the thermoelectric element so that the heat receiving surface of the thermoelectric element and the cooling when receiving a hot air current from a fire. Since an electromotive force is generated due to a temperature difference from the surface, the buzzer and the LED are operated by this electromotive force to output a fire alarm.

JP 2000-194967 A JP 2001-134862 A JP 2007-310795 A Japanese Unexamined Patent Publication No. 7-44784 Japanese Utility Model Publication No.59-15194

  By the way, in the conventional differential heat sensor, it is necessary to satisfy a legally defined operation test and non-operation test in order to obtain a sensitivity for detecting a fire with high accuracy.

  For example, in the case of one type, the differential heat sensor is tested to emit a fire signal within 30 seconds when it is put into a vertical airflow of 70 centimeters per second, which is 20 degrees higher than room temperature. When a horizontal air flow rising linearly at a rate of 10 degrees per minute is added, it is necessary to satisfy that a fire signal is transmitted within 4.5 minutes.

  In addition, the differential heat sensor inoperability test shows that when it is put into a vertical airflow of 50 centimeters per second, which is 10 degrees higher than room temperature, it does not operate within 1 minute, and the rate is 2 degrees per minute from room temperature. It is necessary to satisfy that it does not operate within 15 minutes when a horizontal air flow rising linearly is applied.

  However, in the conventional fire alarm using a thermoelectric element, in order to secure an electromotive force, a structure for keeping the cooling side of the thermoelectric element at a lower temperature when receiving heat from a fire is shown. There is no one that controls the electromotive force (power generation amount) of the thermoelectric element and has an appropriate sensitivity to satisfy the operation test and the non-operation test required for the differential heat detector. For this reason, there has been a risk of misreporting when the ambient temperature rises, such as in summer.

  In addition, even if a metal substrate that satisfies the above-described operation test and non-operation test at the design stage is arranged on the cooling side, a predetermined operation may occur due to variations in electromotive force characteristics with respect to temperature differences of thermoelectric elements and dimensional errors during assembly. The test and the malfunction test may not be satisfied, and this point is also left as a solution problem.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a thermal sensor that can be adjusted to an appropriate sensitivity as a differential sensor without using a power source by using a thermoelectric element.

(Heat sensor)
The present invention relates to a heat sensor,
A thermoelectric element arranged to expose the heat receiving surface of the sensor housing;
A heating medium disposed in contact with the cooling surface of the thermoelectric element;
A fire detection unit for detecting a fire based on an electromotive force according to a temperature difference between a heat receiving surface and a cooling surface of the thermoelectric element;
Is provided,
It has a sensitivity to operate as a differential heat sensor.

(Heat exchange adjustment mechanism)
The heat sensor is provided with a heat exchange amount adjusting mechanism for adjusting the heat exchange amount between the thermoelectric element and the heat medium.

(Selection of contact area)
The heat exchange amount adjusting mechanism selects and changes the contact area between the thermoelectric element and the heat medium to adjust the heat exchange amount.

(Adjustment of heat exchange amount by thermal conductivity of thermal conductive layer)
The heat capacity adjusting mechanism forms a heat conductive layer between the thermoelectric element and the heat medium, and selects the heat conductivity of the heat conductive layer to adjust the heat exchange amount.

(Heat capacity adjustment mechanism)
It has sensitivity to operate as a differential heat detector by a heat capacity adjusting mechanism that adjusts the heat capacity of the heat medium.

(Mass selection of heat medium)
The heat capacity adjusting mechanism adjusts the heat capacity by selecting the mass of the heat medium according to the sensitivity.

(Mass selection by combination of heat medium blocks)
The heat capacity adjusting mechanism adjusts the heat capacity by selecting the mass of the heat medium by combining one or a plurality of heat medium blocks.

(Mass selection by heat transfer fluid)
The heat sensor includes a container filled with a heat medium liquid as a heat medium,
The heat capacity adjusting mechanism adjusts the heat capacity of the heat medium by selecting the mass according to the amount of the heat medium liquid filled in the container.

(Specific heat selection of heat medium)
The heat capacity adjusting mechanism adjusts the heat capacity by selecting the specific heat of the heat medium according to the sensitivity.

(Fire alarm signal output)
The fire detection unit outputs a fire alarm signal to the outside when a fire is detected.

(Thermal detector's own fire alarm)
The fire detector outputs a fire alarm when a fire is detected.

(Basic effect)
The present invention relates to a heat sensor, wherein a thermoelectric element is disposed so as to expose a heat receiving surface of the sensor housing, a heat medium disposed in contact with a cooling surface of the thermoelectric element, and a heat receiving surface of the thermoelectric element. And a fire detection unit that detects fire based on the electromotive force according to the temperature difference between the cooling surface and the cooling surface. This makes it possible to realize a differential heat detector having an appropriate sensitivity that takes advantage of the fact that no power supply is required.

(Effect of heat exchange amount adjustment mechanism)
In addition, since the heat detector is provided with a heat exchange amount adjusting mechanism for adjusting the heat exchange amount between the thermoelectric element and the heat medium, the predetermined heat test and non-operation test required for the differential heat sensor are performed. Control of the amount of power generation by adjusting the temporal change of the temperature difference of the thermoelectric element by adjusting the heat exchange amount between the thermoelectric element and the heat medium by the heat exchange amount adjusting mechanism when it cannot be satisfied. Therefore, it is possible to realize a differential thermal sensor having an appropriate sensing sensitivity that can be adjusted to an appropriate sensing sensitivity that satisfies the operation test and the inoperative test, and that takes advantage of the advantage that a power source is not required.

(Effect of heat exchange adjustment by changing contact area)
In addition, since the adjustment mechanism adjusts the heat exchange amount by changing the contact area between the thermoelectric element and the heat medium, the contact of the heat medium with the thermoelectric element when receiving a hot air flow from an operation test or a non-operation test. By increasing the area, the temperature difference between the high temperature side temperature and the low temperature side temperature of the thermoelectric element is increased, thereby making it possible to adjust the power generation amount to increase the sensing sensitivity, and the contact of the heat medium with the thermoelectric element By reducing the area, the temperature difference between the high temperature side temperature and the low temperature side temperature of the thermoelectric element can be reduced, thereby making it possible to adjust the power generation amount to be low and the sensitivity to be lowered, and to satisfy the operation test and non-operation test. It is possible to obtain a thermal sensor with high detection accuracy and high sensitivity.

(Effects of adjusting the amount of heat exchange by the thermal conductivity of the heat conduction layer)
In addition, the heat capacity adjustment mechanism forms a heat conduction layer between the thermoelectric element and the heat medium, and selects the heat conductivity of the heat conduction layer to adjust the amount of heat exchange. By changing the thermal conductivity of the heat conductive layer without changing, the heat exchange amount of the heat medium can be adjusted easily and easily.

(Effect of heat capacity adjustment mechanism)
In addition, since the heat capacity adjustment mechanism that adjusts the heat capacity of the heat medium has a sensitivity to operate as a differential heat sensor, it satisfies the predetermined operation test and non-operation test required for the differential heat sensor. If this is not possible, the heat capacity adjustment mechanism adjusts the heat capacity of the heat medium to control the amount of power generated by adjusting the temporal change in the temperature difference of the thermoelectric element, thereby satisfying the operation test and the non-operation test. It is possible to realize a differential thermal sensor that can be adjusted to an appropriate sensitivity and has an appropriate sensitivity that takes advantage of the fact that a power supply is not required.

  Since the heat capacity adjustment mechanism is adjusted according to the material of the heat medium, especially when manufacturing one or two types of sensors with different sensitivities, it is possible to manufacture sensors with different sensitivities by simply replacing the heat medium. Can be shared. In addition to this, it is preferable in manufacturing that fine adjustment is performed by the heat exchange amount adjusting mechanism so as to obtain appropriate sensitivity.

(Effects of heat medium mass selection)
In addition, since the heat capacity adjustment mechanism adjusts the heat capacity by selecting the mass of the heat medium according to the sensitivity, the heat capacity is determined by the product of the mass of the heat medium and the specific heat, so the heat capacity is selected by selecting the mass of the heat medium. Adjustable.

(Effect of mass selection by combination of heat medium blocks)
Also,
The heat capacity adjustment mechanism adjusts the heat capacity by selecting the mass of the heat medium by combining one or a plurality of heat medium blocks, so the mass of the heat medium can be simplified by selecting the number of heat medium block combinations to be a unit mass. And it can be determined easily and the heat capacity of the heat medium can be adjusted.

(Effect of mass selection by heat medium liquid)
The heat detector includes a container filled with a heat medium liquid as a heat medium, and the heat capacity adjustment mechanism adjusts the heat capacity of the heat medium by selecting a mass according to the amount of the heat medium liquid filled in the container. Therefore, the mass is determined by the heat medium liquid filled in the container, and the heat capacity of the heat medium can be adjusted easily and with high accuracy.

(Effect by selecting specific heat of heat medium)
Since the heat capacity adjustment mechanism adjusts the heat capacity by selecting the specific heat of the heat medium according to the sensitivity, the heat capacity is determined by the product of the mass of the heat medium and the specific heat, so by selecting the specific heat of the heat medium (material selection) The heat capacity can be adjusted.

(Effects of fire alarm signal output)
In addition, since the fire detection unit outputs a fire alarm signal to the outside when a fire is detected, when connected to the sensor line from the receiver, the heat detector from the receiver via the sensor line There is no need to supply power to the heater, and a fire alarm signal can be sent from the heat detector to the receiver to output a fire alarm.

(Effect of fire alarm of fire detector itself)
In addition, since the fire detection unit outputs a fire alarm when a fire is detected, it can be used as a residential fire alarm that detects the fire with the heat detector itself and outputs an alarm sound and an alarm display. Since a battery power source is not required, it is possible to monitor a fire in a house for a long period of time without managing battery exhaustion.

Explanatory drawing which showed in the adjustment state which made 1st Embodiment of the heat sensor which adjusts the heat exchange amount with a contact area the maximum detection sensitivity. Explanatory drawing which showed the adjustment state which made the detection sensitivity of the heat sensor of FIG. 1 the minimum. The block diagram which showed the sensor circuit provided in the heat sensor of FIG. FIG. 1 is a time chart showing operating characteristics of a thermoelectric element when receiving a hot air flow in the embodiment of FIG. The block diagram which showed the other example of the sensing circuit provided in the thermal sensor of FIG. Explanatory drawing which showed 2nd Embodiment of the heat sensor which adjusts the amount of heat exchange with the thermal radiation amount of a heat medium. Explanatory drawing which showed 3rd Embodiment of the heat sensor which adjusts the amount of heat exchange with the heat conductivity of the heat conductive layer formed between the thermoelectric element and the heat medium. Explanatory drawing which showed 4th Embodiment of the heat sensor which adjusts a heat capacity with the mass of a heat carrier. Explanatory drawing which showed 5th Embodiment of the heat sensor which adjusts a heat capacity with the number of heat-medium blocks. Explanatory drawing which showed 6th Embodiment of the heat sensor which adjusts a heat capacity with the quantity of a heat-medium liquid. Explanatory drawing which showed 7th Embodiment of the heat sensor which adjusts a heat capacity with the specific heat of a heat medium.

[First Embodiment of Heat Sensor]
FIG. 1 is an explanatory view showing an adjustment state in which the first embodiment of the heat detector that adjusts the heat exchange amount according to the contact area is set to the maximum detection sensitivity, and FIG. 1 (A) shows a cross section seen from the side. FIG. 1B shows a plan view with the circuit housing part removed.

(Structure of heat sensor)
As shown in FIG. 1, in the heat sensor 10 of the present embodiment, a thermoelectric element 14 using a Peltier element is fixedly disposed on the lower surface of a sensor housing 12 made of synthetic resin with a heat receiving surface exposed to the outside, The thermoelectric element 14 has, for example, a rectangular thin plate shape when viewed from the plane. A heat medium 16 is disposed in contact with the back surface, which is the cooling surface of the thermoelectric element 14. The thermoelectric element 14 generates an electromotive force according to the temperature difference between the heat receiving surface exposed to the outside and the cooling surface on which the heat medium 16 is disposed in contact.

  The heat medium 16 is a rectangular block member made of, for example, aluminum having high thermal conductivity, and has a size of (W × L1 × H) in length, width, and height, and is formed inside the sensor housing 12. The box-shaped heat medium storage unit 18 is slidably disposed in the longitudinal direction.

  The heat medium 16 is provided so that the heat exchange amount can be adjusted by changing the contact area with the thermoelectric element 14 by a heat exchange amount adjusting mechanism. The heat exchange amount adjusting mechanism of the heat medium 16 is formed with a screw hole 22 having a predetermined length in the left direction from the right end, and through a through hole 21 formed in the standing wall on the right side of the heat medium storage unit 18 with respect to the screw hole 22. The adjustment screw 20 is screwed in, and a jig through hole 24 is formed in the portion of the sensor housing 12 facing the head 20a of the adjustment screw 20 and is normally closed by a removable rubber cap 25. .

  In addition, a circuit housing portion 26 is provided in the sensor housing 12, and a sensor circuit that receives a supply of power generated by the thermoelectric element 14 and detects a fire is mounted on the circuit housing portion 26.

(Adjustment of sensitivity)
In the heat medium 16 shown in FIG. 1, the area in contact with the entire cooling surface on the back side of the thermoelectric element 14 is adjusted to the maximum contact area (W × L1), and the heat to the cooling surface of the thermoelectric element 14 and the heat medium 16 is adjusted. The amount of exchange is adjusted to the maximum.

  When the thermoelectric element 14 receives a thermal airflow from a fire or a test hot airflow at the heat receiving surface in an adjusted state where the contact between the heat medium 16 and the thermoelectric element 14 is the maximum contact area (W × L1), the heat receiving surface is caused by the hot air current. Although it is heated to a high temperature side, the cooling surface of the thermoelectric element 14 is in contact with the heat medium 16 in the maximum area, so that the time change of the temperature rise with respect to the room temperature at that time is greatly suppressed, and as a result The temperature difference between the heat receiving surface and the cooling surface of the thermoelectric element 14 is increased, the voltage due to the electromotive force resulting from the temperature difference is increased, and the sensing sensitivity for detecting a fire is adjusted to a high state. As a result, it is possible to adjust to increase the sensitivity of the thermoelectric element 14 by increasing the amount of power generation.

  FIG. 2 is an explanatory view showing an adjustment state in which the sensitivity of the heat detector of FIG. 1 is minimized, FIG. 2 (A) shows a cross section seen from the side, and FIG. 2 (B) shows the circuit housing portion. The removed plane is shown.

  As shown in FIG. 2, the rubber cap 25 is removed, a screwdriver is inserted through the jig through hole 24, and the adjusting screw 20 is turned in a loosening direction, whereby the heat medium 16 is slid to the left, The contact area of the heat medium 16 that contacts the cooling surface on the back side of the thermoelectric element 14 is adjusted to the minimum contact area (W × L2) at the position in contact with the left standing wall of the medium storage unit 18. And the heat exchange amount with respect to the cooling surface of the heat medium 16 is adjusted to a minimum. As a result, it is possible to adjust the power generation amount of the thermoelectric element 14 to be small and the sensitivity to be lowered.

  When the thermoelectric element 14 receives a thermal airflow due to a fire or a hot airflow from a test in an adjusted state where the contact between the heat medium 16 and the thermoelectric element 14 is the minimum contact area (W × L2), the heat-receiving surface is caused by the hot airflow. Although it is heated to a high temperature side, since the cooling surface of the thermoelectric element 14 is in contact with the heat medium 16 with a minimum area, the action of suppressing the temperature change with respect to the room temperature at that time is reduced, As a result, the temperature difference between the heat receiving surface and the cooling surface of the thermoelectric element 14 is smaller than in the case of the maximum contact area, the voltage due to the electromotive force due to the temperature difference is also reduced, and the sensitivity for detecting a fire is increased. It will be adjusted to a low state.

  For this reason, when adjusting the heat sensor 10 of this embodiment to the sensitivity of a differential heat sensor, for example, as an operation test, a vertical airflow of 70 centimeters per second higher than the room temperature is used as an operation test. When fired, the fire signal is sent within 30 seconds, and when a horizontal air flow rising linearly at a rate of 10 degrees per minute from room temperature is added, the fire signal is sent within 4.5 minutes. In addition, the contact area of the heat medium 16 with respect to the thermoelectric element 14 is adjusted, and as a non-operation test, when it is put into a vertical airflow of 50 centimeters per second higher than room temperature, it does not operate within 1 minute, and The contact area of the heat medium 16 with respect to the thermoelectric element 14 is adjusted so that it does not operate within 15 minutes when a horizontal air flow rising linearly at a rate of 2 degrees per minute from room temperature is applied.

  In addition, since the heat exchange amount adjusting mechanism adjusts the heat exchange amount by changing the contact area between the thermoelectric element 14 and the heat medium 16, the thermoelectric element By increasing the contact area of the heat medium 16 with respect to 14, the temperature difference between the high temperature side temperature and the low temperature side temperature of the thermoelectric element 14 can be increased, thereby making it possible to adjust the power generation amount to increase the sensing sensitivity. By reducing the contact area of the heat medium 16 with the thermoelectric element 14, the temperature difference between the high temperature side temperature and the low temperature side temperature of the thermoelectric element 16 can be reduced, thereby making it possible to adjust the power generation amount to be low and the sensing sensitivity to be low. Thus, the thermal sensor 10 with high operation accuracy having appropriate detection sensitivity satisfying the operation test and the non-operation test can be obtained.

  Note that the heat exchange amount adjusting mechanism of the present embodiment is not limited to the above-described embodiment as long as the contact area of the heat medium 16 in contact with the thermoelectric element 14 is changed, and includes an appropriate mechanism structure. It is.

(Sensor circuit)
3 is a block diagram showing a sensor circuit provided in the heat sensor of FIG. 1, FIG. 3 (A) shows a circuit configuration, and FIG. 3 (B) shows a structure of a thermoelectric element.

  As shown in FIG. 3A, in the detector circuit of this embodiment, the fire detection unit 32 operates using the generated power of the thermoelectric element 14 as a power source when receiving a hot air current due to a fire or a test, and a predetermined power generation is performed. When the voltage is reached, the relay 34 is actuated to close the relay contact 35, and a fire alarm signal is output as a non-voltage contact signal from the sensor terminals 36a and 36b. The thermoelectric element 14 is expressed by an equivalent circuit in which a large number of PN junction elements 30 are connected in series.

  A sensor line drawn from the receiver is connected to the sensor terminals 36a and 36b. By closing the relay contact 35, the sensor line is short-circuited to a low impedance to flow a line current. A fire alarm can be output by sending a signal to the receiver. In this case, it is not necessary to operate the thermal detector 10 by supplying a power supply voltage from the receiver to the heat detector 10 via a sensing line as in a normal fire detector, and the power capacity of the receiver can be reduced.

(The structure of thermoelectric element)
The Peltier element is an element that generates a temperature difference between the front and back when a voltage is applied to the Peltier element, and is used for cooling electronic components. Further, when a temperature difference is applied to the Peltier element, an electromotive force is generated by an action known as the Seebeck effect, and the Peltier element can be used as the thermoelectric element 14 of the present embodiment.

  As shown in FIG. 3B, the Peltier element functioning as the thermoelectric element 14 has a plurality of electrodes 42 and 44 at predetermined intervals on the inner sides of the heat receiving side insulating substrate 38 and the cooling side insulating substrate 40, respectively. The P-type semiconductor 46 and the N-type semiconductor 48 are alternately arranged between the electrodes 42 and 44.

  When a heat difference is applied between the heat-receiving-side insulating substrate 38 and the cooling-side insulating substrate 40 due to the heat from the fire or a test being applied to the heat-receiving-side insulating substrate 38 side, an electromotive force is generated due to power generation. In this power generation action, electrons flow from the electrode 42 connected to the negative terminal 52 to the P-type semiconductor 46, and electrons flow from the P-type semiconductor 46 to the electrode 44.

 Electrons flow from the electrode 44 to the N-type semiconductor 48 and from the N-type semiconductor 48 to the electrode 42. As described above, when electrons flow in the order of the electrode 42, the P-type semiconductor 46, the electrode 44, and the N-type semiconductor 48 from the minus terminal 52 side toward the plus terminal 50 side, between the plus terminal 50 and the minus terminal 52. An electromotive force is generated, and the generated voltage can be supplied to the fire detection unit 32 shown in FIG. 3A connected between the plus terminal 50 and the minus terminal 52 to operate. The power generated by the Peltier element has a relationship proportional to the square of the temperature difference between the heating surface and the cooling surface.

(Adjustment of thermoelectric element temperature difference and generated voltage)
FIG. 4 is a time chart showing the operating characteristics of the thermoelectric element when it receives a hot air flow in the embodiment of FIG. 1, FIG. 4 (A) shows the temperatures of the heat receiving surface and the cooling surface, and FIG. Shows the generated voltage of the thermoelectric element.

  As shown in FIG. 4A, when a thermal air current is applied to the heat detector 10 at time t0, the temperature of the heat receiving surface of the thermoelectric element 14 rises as a straight line 70, and as shown in FIG. When the medium 16 is brought into contact with the thermoelectric element 14 in the maximum area, the temperature of the cooling surface rises gently like a straight line 72-1 due to a large amount of heat transfer, and a straight line 70 that becomes a temperature difference of the thermoelectric element 14 is obtained. And the temperature difference between the straight line 72-1 quickly increases, and a fire is detected at time t1 when the temperature reaches a predetermined threshold temperature ΔT.

  On the other hand, as shown in FIG. 2, the temperature of the cooling surface when the heat medium 16 is brought into contact with the thermoelectric element 14 with the minimum area is as shown by a straight line 72-2 indicated by a dotted line because the heat transfer amount is small. The temperature difference between the straight line 70 and the straight line 72-2, which rises quickly and becomes the temperature difference of the thermoelectric element 14, increases with time delay, reaches a predetermined threshold temperature ΔT at time t2 later than time t1, and fire is detected. The

  FIG. 4B shows a power generation voltage generated by the thermoelectric element 14 in proportion to the square of the temperature difference in FIG. 1A, and depends on the temperature difference between the straight line 70 and the straight line 72-1 in FIG. The power generation voltage rises as indicated by a straight line 74, and a fire is detected when a predetermined threshold voltage Vth is reached at time t1.

  Also, the voltage due to the temperature difference between the straight line 70 and the straight line 72-2 in FIG. 4A rises more slowly than the straight line 74 as shown by the straight line 76, and reaches a predetermined threshold voltage Vth at time t2. A fire is detected.

  In the embodiment of FIG. 1, by adjusting the contact area of the heat medium 14 with respect to the power generation element 14 by the heat exchange amount adjustment mechanism in the range of the maximum area contact state of FIG. 1 and the minimum area contact state of FIG. The temperature characteristics of the cooling surface of the thermoelectric element 14 when receiving the hot air flow shown in FIG. 4A can be adjusted within the range of the slopes of the straight line 72-1 and the straight line 72-2. As a result, FIG. As shown in B), the voltage corresponding to the temperature difference of the thermoelectric element 14 can be adjusted within the range of the slope of the straight line 74 and the straight line 76, thereby enabling the operation test required for the differential heat sensor and As a result, it is possible to obtain a thermal sensor 10 with high operational accuracy and having an appropriate sensing sensitivity that satisfies the inoperative test.

(Another example of sensor circuit)
FIG. 5 is a block diagram showing another example of a sensing circuit provided in the thermal sensor of FIG. As shown in FIG. 5, in the detector circuit of this embodiment, the fire detection unit 32 operates by using the generated power of the thermoelectric element 14 as a power source when a fire or a hot air current due to a test is received, and reaches a predetermined generated voltage. In this case, the buzzer 54 is driven to output a fire alarm sound, and the fire alarm display is performed by turning on, flashing, or blinking the LED 56.

  Thus, the heat sensor 10 of this embodiment which outputs a fire alarm by a fire alarm sound and a fire alarm display can be used as a residential fire alarm that is required to be installed, and does not require a battery power source. Therefore, it is possible to monitor the fire almost permanently without managing the battery exhaustion.

[Second Embodiment of Heat Sensor]
FIG. 6 is an explanatory view showing a second embodiment of the heat detector for adjusting the heat exchange amount by heat radiation of the heat medium. FIG. 6 (A) shows a case where the heat exchange amount is reduced, and FIG. ) Shows the case where the heat exchange amount is increased.

  6A, a thermoelectric element 14 using a Peltier element is fixedly disposed on the lower surface of the sensor housing 12 with the heat receiving surface exposed to the outside, and a cooling surface of the thermoelectric element 14 A flat heat medium 80-1 is arranged in contact with the back side surface, and the thermoelectric element 14 corresponds to the temperature difference between the heat receiving surface exposed to the outside and the cooling surface in which the flat heat medium 80-1 is arranged in contact. Generate electromotive force.

  The flat heat medium 80-1 is a rectangular block member made of, for example, aluminum having a high thermal conductivity, and by reducing the mass, the amount of heat exchange with the cooling surface of the thermoelectric element 14 is reduced. When the temperature change of the cooling surface of the thermoelectric element 14 is increased when receiving a hot air flow due to this, the temperature difference between the heat receiving surface and the cooling surface of the thermoelectric element 14 is reduced, thereby operating as a differential heat sensor. The sensitivity is lowered.

  On the other hand, in the heat sensor 10-2 shown in FIG. 6B, a heat medium 80-2 with a radiation fin is disposed in contact with the back surface, which is a cooling surface of the thermoelectric element 14, and the heat medium 80-2 with a heat radiation fin. Is larger in mass than the flat heat medium 80-1 in FIG. 6A, and the radiation fins 82 are integrally formed on the back side.

  As described above, the heat medium 80-2 with the heat radiation fins has a high heat radiation efficiency and has a large mass, thereby increasing the amount of heat exchange with the cooling surface of the thermoelectric element 14 and receiving a hot air current due to a fire. The temperature change of the cooling surface of the thermoelectric element 14 is reduced, thereby increasing the temperature difference between the heat receiving surface and the cooling surface of the thermoelectric element 14 and increasing the sensitivity when operating as a differential heat sensor.

  As described above, the heat exchange amount adjustment mechanism provided in the heat detector of the present embodiment can select the heat exchange amount with the thermoelectric element by the heat radiation of the heat medium and adjust the sensitivity as the operation type heat detector. it can.

[Third embodiment of heat sensor]
FIG. 7 is an explanatory view showing a third embodiment of a heat sensor that adjusts the amount of heat exchange based on the heat conductivity of the heat conductive layer formed between the thermoelectric element and the heat medium.

  As shown in FIG. 7, the heat sensor 10 of the present embodiment has a back surface serving as a cooling surface of the thermoelectric element 14 that is fixedly disposed with the heat receiving surface exposed to the outside on the lower surface of the sensor housing 12. When the heat medium 16 is arranged in contact with the heat conductive layer 96 and the heat exchange rate of the heat medium 16 is adjusted by selecting the heat conductivity of the heat conductive layer 96, The amount of heat exchange between the cooling surface of the element 14 and the heat medium 16 is increased, and the temperature change of the cooling surface of the thermoelectric element 14 when subjected to a thermal air current due to a fire is reduced, whereby the heat receiving surface and the cooling surface of the thermoelectric element 14 are reduced. The sensitivity when operating as a differential heat sensor is increased.

  On the other hand, when a material having a low thermal conductivity is selected for the heat conductive layer 96, the heat exchange amount between the cooling surface of the thermoelectric element 14 and the heat medium 16 becomes small, and the thermoelectric element in the case of receiving a hot air current due to a fire. The temperature change of the cooling surface 14 is increased, thereby reducing the temperature difference between the heat receiving surface and the cooling surface of the thermoelectric element 14 and reducing the sensitivity when operating as a differential heat detector.

  In the present embodiment, the heat exchange amount can be adjusted without changing the mass of the heat medium 16 by changing the heat conductivity of the heat conductive layer 96.

[Fourth Embodiment of Heat Sensor]
FIG. 8 is an explanatory view showing a fourth embodiment of a heat sensor that adjusts the heat capacity by the mass of the heat medium. FIG. 8A shows the case where the mass of the heat medium is increased, and FIG. Indicates a case where the mass of the heat medium is reduced.

The heat sensor of this embodiment sets the sensitivity to operate as a differential heat sensor by a heat capacity adjustment mechanism that adjusts the heat capacity of the heat medium. Here, the heat capacity C of the heat medium is represented by m as mass and c as specific heat.
C = m × c
Thus, in the present embodiment, the heat capacity C is adjusted by changing the mass m of the heat medium.

  The heat capacity adjusting mechanism of the heat detector 10-1 shown in FIG. 8A is a back side surface serving as a cooling surface of the thermoelectric element 14 fixedly arranged with the heat receiving surface exposed to the outside on the lower surface of the sensor housing 12. And the thermoelectric element 14 generates an electromotive force according to a temperature difference between the heat receiving surface exposed to the outside and the cooling surface on which the large mass heat medium 84-1 is contacted. To do.

  The large-mass heat medium 84-1 is a rectangular block member made of, for example, aluminum, and has a large heat capacity by increasing the mass, and the cooling surface of the thermoelectric element 14 when receiving a hot air current due to a fire. The temperature change is reduced, thereby increasing the temperature difference between the heat receiving surface and the cooling surface of the thermoelectric element 14 and increasing the sensitivity when operating as a differential heat detector.

  On the other hand, in the heat capacity adjustment mechanism of the heat detector 10-2 shown in FIG. 8B, a small-mass heat medium 84-2 is disposed in contact with the back surface that is the cooling surface of the thermoelectric element 14. The small-mass heat medium 84-2 has a small heat capacity by reducing the mass, and increases the temperature change of the cooling surface of the thermoelectric element 14 when receiving a hot air current due to a fire. The temperature difference between the heat receiving surface and the cooling surface is reduced to reduce the sensitivity when operating as a differential heat sensor.

[Fifth Embodiment of Heat Sensor]
FIG. 9 is an explanatory diagram showing a fifth embodiment of a heat sensor that adjusts the heat capacity according to the number of heat medium blocks. FIG. 9A shows a case where five heat medium blocks are stacked, and FIG. B) shows a case where two heat medium blocks are stacked.

  The heat capacity adjustment mechanism of the heat detector 10-1 in FIG. 9A is configured such that five heat medium blocks 86 each having a predetermined unit mass are placed in contact with each other on the back surface serving as the cooling surface of the thermoelectric element 14. Yes. In this way, the mass of the heat medium is increased by placing five small heat medium blocks 86 in contact with each other, the heat capacity is increased by increasing the mass, and the thermoelectric power in the case of receiving a hot air current from a fire. The temperature change of the cooling surface of the element 14 is reduced, thereby increasing the temperature difference between the heat receiving surface and the cooling surface of the thermoelectric element 14 and increasing the sensitivity when operating as a differential heat detector.

  On the other hand, in the heat capacity adjustment mechanism of the heat detector 10-2 in FIG. 9B, two heat medium blocks 86 each having a predetermined unit mass are placed in contact with each other on the back surface serving as the cooling surface of the thermoelectric element 14. Thus, the mass as the heat medium is reduced, the heat capacity is reduced by reducing the mass, and the temperature change of the cooling surface of the thermoelectric element 14 when subjected to a thermal air current due to a fire is increased. The temperature difference between the heat receiving surface and the cooling surface of the element 14 is reduced to reduce the sensitivity when operating as a differential heat detector.

  As described above, in the present embodiment, by arbitrarily determining the number of heat medium blocks 86 to be stacked on the cooling surface of the thermoelectric element 14, the mass of the heat medium can be selected easily and easily to adjust the heat capacity. In addition, the sensitivity when operating as a differential heat sensor can be set.

[Sixth Embodiment of Heat Sensor]
FIG. 10 is an explanatory view showing a sixth embodiment of a heat sensor that adjusts the heat capacity according to the amount of the heat medium liquid. FIG. 10 (A) shows a case where the amount of the heat medium liquid is increased, and FIG. B) shows a case where the amount of the heat medium liquid is reduced.

  In the heat capacity adjustment mechanism of the heat detector 10-1 in FIG. 10A, a tank 88 is disposed in contact with the back surface that is the cooling surface of the thermoelectric element 14, and heat such as water or a cold insulation agent is placed in the tank 88. The medium liquid 90 is filled, and in FIG. 10A, the heat medium liquid 90 is filled so as to be almost full.

  In this way, the heating medium liquid 90 is almost full in the tank 88, so that the mass as the heating medium is increased. By increasing the mass, the heat capacity is increased, and the thermoelectric power in the case of receiving a hot air current due to a fire. The temperature change of the cooling surface of the element 14 is reduced, thereby increasing the temperature difference between the heat receiving surface and the cooling surface of the thermoelectric element 14 and increasing the sensitivity when operating as a differential heat detector.

  On the other hand, in the heat capacity adjustment mechanism of the heat detector 10-2 in FIG. By reducing the mass of the heat transfer medium 90, the heat capacity is reduced, and the temperature change of the cooling surface of the thermoelectric element 14 when subjected to a hot air current due to a fire is increased, whereby the heat receiving surface and the cooling surface of the thermoelectric element 14 are increased. The temperature difference is reduced to reduce the sensitivity when operating as a differential heat sensor.

  As described above, in the present embodiment, the heat capacity of the heat medium can be easily and easily adjusted by selecting the amount of the heat medium liquid 90 filled in the tank 88 disposed in contact with the cooling surface of the thermoelectric element 14. Sensitivity when operating as a dynamic heat sensor can be arbitrarily set. Further, the heat capacity of the heat medium block 86 shown in FIG. 8 is set stepwise depending on the number of the heat medium blocks 86, but in the present embodiment, the heat medium liquid 90 can continuously change the heat capacity depending on the amount, and the differential type The sensitivity can be set more finely and accurately when operating as a heat sensor.

[Seventh Embodiment of Heat Sensor]
FIG. 11 is an explanatory view showing a seventh embodiment of the heat sensor for adjusting the heat capacity by the specific heat of the heat medium. FIG. 11A shows a case where a heat medium having a large specific heat is provided, and FIG. ) Shows a case where a heat medium having a small specific heat is provided.

  Since the heat capacity C of the heat medium is given by the product of the mass m and the specific heat c as described above, the heat capacity adjustment mechanism of the present embodiment adjusts the heat capacity C by selecting the specific heat of the heat medium. It is characterized by that.

  For this reason, in the heat sensor 10-1 in FIG. 11A, an aluminum heat medium 92 having a large specific heat of 0.913 is placed in contact with the back surface serving as the cooling surface of the thermoelectric element 14, while FIG. In the heat sensor 10-2 in (B), a lead heat medium 94 having a specific heat as small as 0.13 is placed in contact with the back surface serving as the cooling surface of the thermoelectric element 14.

  For this reason, the heat detector 10-1 in FIG. 11A has a large heat capacity by disposing an aluminum heat medium 92 having a large specific heat, and the cooling surface of the thermoelectric element 14 in the case of receiving a hot air current due to a fire. The temperature change is reduced, thereby increasing the temperature difference between the heat receiving surface and the cooling surface of the thermoelectric element 14 and increasing the sensitivity when operating as a differential heat detector.

  On the other hand, the heat detector 10-2 of FIG. 11 (B) is a cooling surface of the thermoelectric element 14 in the case where the heat capacity is reduced by arranging the lead heat medium 94 having a small specific heat and a thermal air current due to a fire is received. Thus, the temperature difference between the heat receiving surface and the cooling surface of the thermoelectric element 14 is reduced, and the sensitivity when operating as a differential heat sensor is lowered.

[Modification of the present invention]
The heat exchange amount adjustment mechanism and the heat capacity adjustment mechanism of the heat sensor shown in the above embodiment are not limited thereto, and any appropriate mechanism can be used as long as the heat exchange amount or heat capacity of the heat medium can be selected (changed). Includes structure.

  In the above embodiment, the heat detector having a structure installed on the ceiling surface is taken as an example, but the present invention is not limited to this, and may be an appropriate structure such as a wall-mounted type.

  Moreover, as a detector circuit, in addition to a fire alarm function using a buzzer and an LED, a fire alarm signal may be output to the outside.

  In the above-described embodiment, the fire alarm signal is output to the outside by the operation of the relay. However, a wireless communication unit that operates with the power generated by the thermoelectric element is provided to transmit the fire alarm signal wirelessly. Anyway.

  Further, the adjustment mechanism that changes the contact area and volume of the heat medium may be configured such that, for example, the amount of movement of the heat medium can be recognized from the outside so that the adjustment state can be confirmed. Further, adjustment may be made by direct operation by turning an operation knob or the like without using a jig such as a screwdriver.

  The present invention includes appropriate modifications without impairing the object and advantages thereof, and is not limited by the numerical values shown in the above embodiments.

10, 10-1, 10-2: Heat sensor 12: Sensor housing 14: Thermoelectric element 16: Heat medium 16-1, 16-11: First heat medium 16-2, 16-12: Second heat Medium 18: Heat medium storage unit 20: Adjustment screw 22: Screw hole 24: Jig through hole 25: Rubber cap 26: Circuit storage unit 28: Circuit board 30: PN junction element 32: Fire detection unit 34: Relay 36: Relay Contact point 38: Heat receiving side insulating substrate 40: Cooling side insulating substrate 42, 44: Conductor 46: P-type semiconductor 48: N-type semiconductor 50: Plus terminal 52: Negative terminal 54: Buzzer 56: LED
80-1: Flat heat medium 80-2: Heat medium 82 with heat radiation fins: Heat radiation fin 84-1: Large mass heat medium 84-2: Small mass heat medium 86: Heat medium block 88: Tank 90: Heat medium liquid 92 : Aluminum heat medium 94: Lead heat medium 96: Heat conduction layer

Claims (11)

A thermoelectric element disposed with the heat receiving surface exposed to the sensor housing;
A heating medium disposed in contact with the cooling surface of the thermoelectric element;
A fire detection unit for detecting a fire based on an electromotive force according to a temperature difference between the heat receiving surface and the cooling surface of the thermoelectric element;
Is provided,
A heat sensor characterized by having a sensitivity to operate as a differential heat sensor.
The heat sensor according to claim 1,
The heat sensor is
A heat sensor comprising a heat exchange amount adjustment mechanism for adjusting a heat exchange amount between the thermoelectric element and the heat medium.
The heat sensor according to claim 2,
The heat detector adjusts the amount of heat exchange by selecting a contact area between the thermoelectric element and the heat medium.
The heat sensor according to claim 2,
The heat capacity adjusting mechanism forms a heat conductive layer between the thermoelectric element and the heat medium, and selects the heat conductivity of the heat conductive layer to adjust the heat exchange amount. .
The heat sensor according to claim 1,
A heat sensor having a sensitivity to operate as the differential heat sensor by a heat capacity adjusting mechanism for adjusting a heat capacity of the heat medium.
The heat sensor according to claim 5, wherein
The heat capacity adjusting mechanism adjusts the heat capacity by selecting a mass of the heat medium according to the sensitivity.
The heat sensor according to claim 5, wherein
The heat capacity adjusting mechanism adjusts the heat capacity by selecting the mass of the heat medium by a combination of one or a plurality of heat medium blocks.
The heat sensor according to claim 4, wherein
The heat sensor includes a container filled with a heat medium liquid as the heat medium,
The heat capacity adjusting mechanism adjusts the heat capacity of the heat medium by selecting the mass according to the amount of the heat medium liquid filled in the container.
The heat sensor according to claim 5, wherein
The heat capacity adjusting mechanism adjusts the heat capacity by selecting a specific heat of the heat medium according to the sensitivity.
2. The heat sensor according to claim 1, wherein the fire detector outputs a fire alarm signal to the outside when a fire is detected.
  The heat sensor according to claim 1, wherein the fire detection unit outputs a fire alarm when a fire is detected.

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