JP2019003439A - Heat detector - Google Patents

Abstract

To provide a high precision heat detector for surely detecting fire at nominal operation temperature as a constant temperature heat detector in need of no power source by using a thermoelectric element.SOLUTION: In a heat detector 10, a heat generation element 16 for cooling is arranged whose endothermic surface 16a is made to contact with a cooling surface 14b of a thermoelectric element 14 for power generation arranged with a heat receiving surface 14a of a detector housing being exposed via a heat medium 15. A constant temperature controller 24 operates when a power generation voltage from the thermoelectric element 14 for power generation reaches a prescribed voltage to perform control such that the heat generation element 16 for cooling is energized so as to maintain temperature of the cooling surface 14b of a thermoelectric element 14 for power generation detected by a temperature sensor 30 at a prescribed cooling target temperature via the heat medium 15 for cooling.SELECTED DRAWING: Figure 2

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 constant temperature heat sensor using a bimetal is known as a heat sensor that detects a fire without requiring a power source (Patent Document 1).

  The constant temperature type heat sensor is activated when the temperature of the internal heat sensitive part rises above a certain level due to the heat of the fire. The heat sensitive part is a combination of two types of metal plates called bimetal, which have different coefficients of thermal expansion. The metal that expands well when receiving heat is bent to the outside, and the metal that does not expand much is bent to the inside. The electrical contact closes depending on the bending condition. In many cases, the nominal operating temperature at which the constant temperature type heat sensor operates is set to 75 ° C. or 65 ° C.

  However, the constant temperature type heat detector is provided with a bimetal as a heat sensitive portion, so that a large arrangement space is required in the housing and the size is increased, and it is difficult to reduce the thickness of the heat detector and improve the design. There is also a constant temperature type heat detector using a thermistor in the heat sensitive part, which can be reduced in thickness, but requires a power source.

  On the other hand, fire alarms using thermoelectric elements known as Peltier elements are known as fire alarms that detect and alert fire without requiring a power source (Patent Documents 2 to 4).

  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-A-9-147258 JP 2007-310795 A Japanese Unexamined Patent Publication No. 7-44784 Japanese Utility Model Publication No.59-15194

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

  The operation test of the constant temperature type heat sensor is a fire within a period of 120 seconds for one type and within 300 seconds for a second type when it is put into a vertical air flow of 1 meter per second at a temperature of 125% of the nominal operation test temperature. Sending a signal needs to be met.

  However, a conventional fire alarm using a thermoelectric element shows a structure that keeps the cooling side of the thermoelectric element at a lower temperature when it receives heat from a fire, but it gradually relaxes over time. However, the temperature on the cooling side also rises, and compared with the case where the cooling side is kept at a constant temperature, the delay time from when the nominal operating temperature is reached to when the fire signal is emitted is the amount by which the temperature on the cooling side has increased. In some cases, the operation test required for the constant temperature type heat sensor may not be satisfied, and this point remains as a problem to be solved.

  An object of the present invention is to provide a highly accurate heat sensor that reliably detects a fire at a nominal operating temperature as a constant temperature type heat sensor without using a power source by using a thermoelectric element.

(Constant temperature sensor)
The present invention relates to a heat sensor,
A thermoelectric element for power generation that is disposed with the heat receiving surface exposed to the sensor housing and outputs a power generation voltage according to a temperature difference between the heat receiving surface and the cooling surface;
A cooling thermoelectric element disposed in direct contact with the cooling surface of the power generation thermoelectric element directly or indirectly through a heat medium; and
A constant temperature control unit for controlling the temperature of the cooling surface of the thermoelectric element for power generation to maintain a predetermined temperature by energizing the thermoelectric element for cooling when the generated voltage is obtained from the thermoelectric element for power generation;
A fire detection unit for detecting a fire based on a power generation voltage from a thermoelectric element for power generation;
Is provided.

(Constant temperature feedback control)
The constant temperature controller
A temperature sensor for detecting the temperature on the cooling surface side of the thermoelectric element for power generation;
A power supply unit that outputs a predetermined power supply voltage when the generated voltage from the thermoelectric element for power generation reaches a predetermined voltage;
A feedback control unit that operates in response to the supply of the power supply voltage from the power supply unit and controls the cooling thermoelectric element so as to maintain the temperature of the cooling surface of the power generation thermoelectric element detected by the temperature sensor at a predetermined cooling target temperature;
Is provided.

(Constant temperature control by temperature resistance element)
The constant temperature controller
A temperature resistance element whose resistance value changes depending on the temperature disposed on the cooling surface side of the thermoelectric element for power generation; and
A power supply unit configured to supply a predetermined power supply voltage to the cooling thermoelectric element via the temperature resistance element to cool the cooling surface of the power generation thermoelectric element when the generated voltage from the power generation thermoelectric element reaches a predetermined voltage;
Is provided.

(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 detector, wherein a heat receiving surface of a sensor housing is exposed to be disposed, and a thermoelectric element for power generation that outputs a power generation voltage according to a temperature difference between the heat receiving surface and a cooling surface, A thermoelectric element for cooling arranged with the endothermic surface in direct contact with the cooling surface of the thermoelectric element directly or indirectly through a heat medium, and when the generated voltage is obtained from the thermoelectric element for power generation, the cooling thermoelectric element is energized Therefore, a constant temperature control unit that controls the temperature of the cooling surface to maintain a predetermined temperature and a fire detection unit that detects a fire based on the generated voltage from the thermoelectric element for power generation are provided. The cooling surface side of the thermoelectric element for power generation is cooled by energization of the cooling thermoelectric element by the constant temperature control unit, and is kept at a predetermined constant temperature and does not change. The generated voltage corresponding to the temperature difference from the nominal operating temperature of the surface is obtained. Fire can be detected, it is possible to perform fire detection by nominal operating temperature with high accuracy when.

(Constant temperature feedback control)
The constant temperature control unit includes a temperature detector that detects the temperature on the cooling surface side of the thermoelectric element for power generation, and a power supply unit that outputs a predetermined power supply voltage when the generated voltage from the thermoelectric element for power generation reaches a predetermined voltage And feedback control for controlling the cooling thermoelectric element so that the temperature of the cooling surface of the thermoelectric element for power generation detected by the temperature detector is maintained at a predetermined cooling target temperature. Therefore, the control to keep the cooling surface of the thermoelectric element for power generation at a constant temperature by the operation of the thermoelectric element for cooling is accurately performed and stabilized, and the fire detection at the nominal operating temperature can be performed with high accuracy. it can.

(Constant temperature control by temperature resistance element)
Further, the constant temperature control unit includes a temperature resistance element whose resistance value changes depending on the temperature disposed on the cooling surface side of the power generation thermoelectric element, and a predetermined power source when the power generation voltage from the power generation thermoelectric element reaches a predetermined voltage. For example, when a thermistor is used as the temperature resistance element, the thermistor rises in temperature because a voltage is supplied to the cooling thermoelectric element via the temperature resistance element to cool the cooling surface of the power generation thermoelectric element. Therefore, if the temperature on the cooling surface side of the thermoelectric element for power generation rises due to the hot air flow, the value of the thermistor decreases, and the resistance value decreases, and the drive that flows to the cooling thermoelectric element As the current increases, the temperature on the heat absorption surface decreases, the temperature on the cooling surface side of the thermoelectric element for power generation decreases, and when the temperature decreases, the resistance value of the thermistor increases and the drive current of the cooling thermoelectric element decreases to absorb heat. Surface temperature is Pressurized, and can be stabilized by a simple configuration the temperature of the cooling surface of the power generating thermoelectric element by the repetition.

(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 1st Embodiment of the heat sensor. 1 is a block diagram showing an embodiment of a sensor circuit provided in the thermal sensor of FIG. Explanatory drawing which showed schematic structure of the thermoelectric element for electric power generation provided in the heat sensor of FIG. 1, and the thermoelectric element for cooling Time chart showing the operation of the sensor circuit in FIG. The block diagram which showed other embodiment of the sensor circuit provided in the heat sensor of FIG.

[First Embodiment of Heat Sensor]
FIG. 1 is an explanatory view showing a first embodiment of a heat sensor, FIG. 1 (A) shows a cross section seen from the side, and FIG. 1 (B) shows a plan view with a circuit housing part removed. .

(Structure of heat sensor)
As shown in FIG. 1, in the heat sensor 10 of this embodiment, a thin rectangular thermoelectric generator 14 using a Peltier element is exposed on the lower surface of a sensor housing 12 made of synthetic resin, and the heat receiving surface 14a is exposed to the outside. And fixedly arranged. A heat medium 15 is disposed in contact with the cooling surface 14 b on the back side of the thermoelectric element 14 for power generation.

  The heat medium 15 is a rectangular block member made of, for example, aluminum having high thermal conductivity, and is disposed in the storage frame 22 in the sensor housing 12. The thermoelectric element 14 for power generation generates a power generation voltage corresponding to the temperature difference between the heat receiving surface 14a exposed to the outside and the cooling surface 14b disposed in contact with the heat medium 15.

  A cooling thermoelectric element 16 is disposed on the back surface of the heat medium 15. When a driving current flows, the cooling thermoelectric element 16 moves heat from the heat absorption surface 16a in contact with the heat medium 15 to the heat radiation surface 16b exposed on the back surface, and the thermoelectric element for power generation through the heat medium 15 The 15 cooling surfaces 14b are cooled.

  In addition, a circuit housing portion 18 is provided in the sensor housing 12. The circuit housing portion 18 is supplied with the power generation voltage of the power generation thermoelectric element 14 to detect a fire, and the cooling thermoelectric element 16 generates a thermoelectric power for generation. A sensor circuit for controlling the cooling surface 14b of the element 14 to a constant temperature is mounted.

[Sensor circuit]
FIG. 2 is a block diagram illustrating an embodiment of a sensor circuit provided in the thermal sensor of FIG.

(Fire detection part)
As shown in FIG. 2, the detector circuit of the heat detector 10 is provided with a fire detection unit 32, to which the power generation voltage Vgen generated by the power generation thermoelectric element 14 is supplied, and the power generation voltage Vgen is predetermined. A fire is detected when a fire threshold value Vf corresponding to a nominal operating temperature set in advance as a constant temperature heat sensor is reached.

  A buzzer 34, an LED 36 and a relay 38 are connected to the fire detection unit 32. When the fire detector 32 detects a fire from the power generation voltage Vgen of the thermoelectric element 14 for power generation, the buzzer 34 is sounded to output a fire alarm sound, the LED 36 is turned on, blinks or flickers to display a fire alarm, The relay 38 is operated to close the relay contact 40, and a fire alarm signal is output as a non-voltage contact signal from the sensor terminals 42a and 42b.

  A sensor line drawn from the receiver is connected to the sensor terminals 42a and 42b. When the relay contact 40 is closed, the sensor line is short-circuited to a low impedance to cause a line current to flow. Can be sent to the receiver to output a fire alarm. 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.

(Constant temperature controller)
As shown in FIG. 2, a constant temperature control unit 24 is provided in the sensor circuit of the heat sensor 10. The constant temperature control unit 24 includes a DC / DC converter 26 that functions as a power supply unit, a feedback control unit 28, and a temperature sensor 30 provided in the heat medium 15. As the temperature sensor 30, a thermistor, a PN junction element, a platinum temperature measuring element, or the like is used.

  The DC / DC converter 26 operates when the power generation voltage Vgen output from the thermoelectric element 14 for power generation reaches a predetermined start-up voltage Vst when receiving a thermal airflow due to a fire or a test, and feedback-controls the power supply voltage Vc. The unit 28 is supplied to operate.

  A temperature signal detected by the temperature sensor 30 provided in the heat medium 15 is input to the feedback control unit 28, and is detected by the temperature sensor 30 when operated with the supply of the power supply voltage Vc from the DC / DC converter 26. The driving current is supplied to the cooling thermoelectric element 16 so as to keep the temperature of the heat generating medium 15 and the temperature of the cooling surface 14b of the thermoelectric generating element 14 in contact with the heating medium 15 at the predetermined cooling target temperature To. To control the cooling surface 14b of the thermoelectric element 14 for power generation through the heat medium 15.

  The feedback control unit 28 is provided with, for example, an error amplifier and a reference voltage source for setting a reference voltage Vref corresponding to the cooling target temperature To, and a feedback signal voltage corresponding to an error between the temperature detection voltage Vt by the temperature sensor 30 and the reference voltage Vref. When Vt> Vref, the feedback signal voltage Vf is increased to increase the drive current flowing through the cooling thermoelectric element 16, and when Vt <Vref, the feedback signal voltage Vf is decreased or stopped for cooling. The drive current that flows through the thermoelectric element 16 is reduced, whereby control is performed to maintain the temperature of the cooling surface 14a of the power generation thermoelectric element 14 at a predetermined cooling target temperature To via the heat medium 15.

[Structure of thermoelectric element]
FIG. 3 is an explanatory diagram showing a schematic structure of a power generation thermoelectric element and a cooling thermoelectric element provided in the heat detector of FIG.

  The Peltier element is an element that generates a temperature difference between the front and back when a voltage is applied, and is used as the cooling thermoelectric element 16 of the present embodiment. 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 is used as the thermoelectric element 14 for power generation of this embodiment.

(Structure of thermoelectric element for power generation)
As shown in FIG. 3, in the Peltier element functioning as the thermoelectric element 14 for power generation, a plurality of electrodes 46 and 48 are alternately arranged at predetermined intervals on the inner sides of the heat receiving side insulating substrate 42 and the cooling side insulating substrate 44, respectively. The P-type semiconductor 50 and the N-type semiconductor 52 are alternately arranged between the electrodes 46 and 48.

  A voltage is generated by a power generation action when a temperature difference occurs between the heat-receiving side insulating substrate 42 and the cooling-side insulating substrate 44 due to the heat of a hot air flow from a fire or test applied to the heat-receiving side insulating substrate 42 side.

  In this power generation action, electrons flow from the electrode 46 connected to the negative terminal 66 a to the P-type semiconductor 50, and electrons flow from the P-type semiconductor 50 to the electrode 48. Electrons flow from the electrode 48 to the N-type semiconductor 52 and from the N-type semiconductor 52 to the electrode 46, and a generated voltage Vgen is generated between the plus terminal 50 and the minus terminal 52.

  The generated voltage Vgen generated between the plus terminal 50 and the minus terminal 52 of the power generation thermoelectric element 14 is supplied to the sensor circuit shown in FIG. 3A and can be operated. The power generation voltage Vgen of the Peltier element that functions as the power generation thermoelectric element 14 is proportional to the square of the temperature difference between the heat receiving surface 14a and the cooling surface 14b.

(Structure of thermoelectric element for cooling)
As shown in FIG. 3, in the Peltier element functioning as the cooling thermoelectric element 16, a plurality of electrodes 58, 60 are alternately arranged at predetermined intervals on the inner side of the heat absorption side insulating substrate 54 and the heat radiation side insulating substrate 56, respectively. The P-type semiconductor 62 and the N-type semiconductor 64 are alternately arranged between the electrodes 58 and 60 and have the same structure as the thermoelectric element 14 for power generation.

  When a driving voltage is applied between the plus terminal 68a and the minus terminal 68b drawn from the cooling thermoelectric element 16, the electrode 58, the P-type semiconductor 62, the electrode 60, and the N-type are directed from the plus terminal 68s side to the minus terminal 68b side. A current flows in the order of the semiconductor 64, heat is transferred from the heat absorption side insulating substrate 54 to the heat dissipation side insulating substrate 56, the heat medium 15 disposed on the heat absorption side insulating substrate 54 side is cooled, and further, via the heat medium 15. Thus, the cooling-side insulating substrate 42 that becomes the cooling surface of the power generation thermoelectric element 14 is cooled.

[Thermal sensor operation]
FIG. 4 is a time chart showing the operation of the sensor circuit of FIG. 2 when receiving a hot air current. FIG. 4A shows the temperature change of the heat receiving surface 14a and the cooling surface 14b in the thermoelectric element 14 for power generation. 4B shows the cooling timing of the cooling thermoelectric element by the DC / DC converter 26, and FIG. 4C shows the timing of fire detection by the fire detection unit 32.

  As shown in FIG. 4, if the heat sensor 10 of the present embodiment receives a fire or an airflow due to a test at time t 0, as shown in FIG. 4A, the heat receiving surface temperature T 1 of the power generation thermoelectric element 14 is As the time elapses, the cooling surface temperature T2 rises gently because it is in the sensor housing 12, and the thermoelectric element 14 for power generation has a temperature between the heat receiving surface temperature T1 and the cooling surface temperature T2. A power generation voltage Vg proportional to the square of the difference (T1-T2) is output.

  The DC / DC converter 26 shown in FIG. 2 operates when the power generation voltage Vgen from the power generation thermoelectric element 14 reaches a predetermined activation voltage Vst, and operates by supplying the power supply voltage Vc to the feedback control unit 28. At time t2 of (A), the temperature of the cooling surface 14b of the thermoelectric element 14 for power generation is controlled to a predetermined cooling target temperature To, and the cooling surface temperature T2 that has started to rise gradually is controlled to maintain the cooling target temperature To. Is done.

  For this reason, the thermoelectric element 14 for power generation outputs a power generation voltage Vgen proportional to the square of the temperature difference (T1-T2) between the temperature T1 of the heat receiving surface 14a and the temperature T2 of the cooling surface 14b that is controlled at the cooling target temperature To. When the fire detection unit 32 reaches the fire threshold voltage Vf corresponding to the power generation voltage Vgen proportional to the square of the temperature difference (Tθ−To) between the nominal operating temperature Tθ and the cooling target temperature To at time t2, FIG. As shown in (C), a fire detection operation is performed, and a fire alarm and a fire alarm signal are output.

  Note that the cooling target temperature To in the constant temperature control of the cooling thermoelectric element 16 is set to, for example, To = 20 ° C. corresponding to, for example, the average room temperature of the year, and FIG. 4A shows hot air from time t0. The case where the room temperature before receiving the flow is the same as the cooling target temperature To is taken as an example.

[Other Embodiments of Sensor Circuit]
FIG. 5 is a block diagram illustrating an embodiment of a sensor circuit provided in the thermal sensor of FIG.

(Fire detection part)
As shown in FIG. 5, the fire detection unit 32 provided in the sensor circuit of the heat sensor 10 of the present embodiment is the same as that of the embodiment of FIG. 2, and the generated voltage generated by the power generation thermoelectric element 14. When Vgen reaches the fire threshold value Tf corresponding to the nominal operating temperature as a constant temperature type heat detector, a fire is detected, the buzzer 34 is sounded and a fire alarm sound is output, and the LED 36 is turned on, blinks or blinks. A fire alarm is displayed, the relay 38 is operated to close the relay contact 40, and a fire alarm signal is output as a non-voltage contact signal from the sensor terminals 42a and 42b.

(Constant temperature controller)
As shown in FIG. 5, the constant temperature control unit 24 provided in the sensor circuit of the heat sensor 10 includes a thermistor 70 provided in the heat medium 15 arranged on the cooling surface 14 a side of the thermoelectric element 14 for power generation, DC that functions as a power supply unit that supplies a predetermined power supply voltage Vc to the cooling thermoelectric element 16 via the thermistor 70 and cools it when the generated voltage Vgen from the thermoelectric element 14 for generation reaches a predetermined starting voltage Vst. / DC converter 24. The thermistor 70 functions as a temperature resistance element whose resistance value decreases as the temperature rises. Further, the thermistor 30 may be disposed directly on the cooling surface 14b of the thermoelectric element 14 for power generation.

  The operation of the constant temperature control unit 24 according to the present embodiment is as follows. When the thermoelectric element 14 for power generation receives a fire or an air flow from a test, the thermoelectric element 14 for power generation generates power in proportion to the square of the temperature difference (T1-T2) between the temperature T1 of the heat receiving surface 14a and the temperature T2 of the cooling surface 14b. The voltage Vg is output.

  The DC / DC converter 26 operates when the power generation voltage Vgen from the power generation thermoelectric element 14 reaches a predetermined start-up voltage Vst, supplies a predetermined power supply voltage Vc to the cooling thermoelectric element 16 via the thermistor 70, and performs cooling. A driving current flows through the thermoelectric element 16, and the cooling surface 14 a of the power generation thermoelectric element 14 is cooled via the heat medium 70.

  At this time, the thermistor 70 disposed in the heat medium 15 gradually increases in temperature due to the temperature rise of the cooling surface 14b of the power generation thermoelectric element 14 receiving the hot air flow, and the resistance value increases due to the temperature rise. The drive current flowing through the cooling thermoelectric element 16 is increased due to the decrease in resistance value, and the heat absorbed is increased. As a result, the temperature of the heat medium 15 is decreased.

  When the temperature of the heat medium 15 is lowered, the resistance value of the thermistor 70 is increased, the drive current flowing through the cooling thermoelectric element 16 is lowered, the heat absorbed is decreased, and as a result, the temperature of the heat medium 15 is increased. By repeating this, the temperature on the cooling surface 14a side of the thermoelectric element 14 for power generation is stabilized at a certain temperature.

  When the temperature on the cooling surface 14 a side of the thermoelectric element 14 for power generation is stabilized by the constant temperature control unit 24 having a simple configuration using the thermistor 70, the temperature of the heat receiving surface 14 b at which the thermoelectric element 14 for power generation is at a high temperature. And a power generation voltage Vgen proportional to the square of the temperature difference between the temperature of the cooled cooling surface 14b and the stabilized temperature of the cooling surface 14b, and the fire detection unit 32 generates a temperature difference (Tθ−To) between the nominal operating temperature Tθ and the cooling target temperature To. When the fire threshold voltage Vf corresponding to the squarely proportional power generation voltage Vgen is reached, a fire is detected and a fire alarm is output or a fire alarm signal is output.

[Modification of the present invention]
In the above embodiment, the cooling thermoelectric element is disposed on the cooling surface of the power generation thermoelectric element via the heat medium. However, the present invention is not limited to this, and the cooling thermoelectric element is directly disposed on the cooling surface of the power generation thermoelectric element. It may be arranged.

  Moreover, although said embodiment has taken the heat sensor of the structure installed in a ceiling surface as an example, it is not limited to this, For example, it is good also as appropriate structures, such as a wall hanging type.

  In the above 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 generated voltage of the thermoelectric element for power generation is provided, and the fire alarm signal is transmitted wirelessly. You may make it do.

  In addition, if a buzzer and LED are provided to provide a fire alarm that outputs a fire alarm with a fire alarm sound and a fire alarm display, it can be used as a residential fire alarm that is obligated to be installed. This makes it possible to monitor fires almost permanently without managing battery exhaustion.

  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: Heat sensor 12: Sensor housing 14: Thermoelectric element 14a for power generation: Heat receiving surface 14b: Cooling surface 16: Heat medium 16: Thermoelectric element 16a for cooling: Heat absorption surface 16b: Heat radiation surface 18: Heat medium storage unit 20 : Circuit board 22: Storage frame 24: Constant temperature control unit 26: DC / DC converter 28: Feedback control unit 30: Temperature sensor 32: Fire detection unit 34: Buzzer 36: LED
38: Relay 40: Relay contact 42: Heat receiving side insulating substrate 44: Cooling side insulating substrate 46, 48, 58, 60: Conductor 50, 62: P type semiconductor 52, 64: N type semiconductor 54: Heat absorbing side insulating substrate 56: Heat dissipation side insulating substrates 66a, 68a: plus terminals 66b, 68b: minus terminals 70: thermistors

Claims (5)

A thermoelectric element for power generation that is disposed with the heat receiving surface exposed to the sensor housing and outputs a power generation voltage corresponding to a temperature difference between the heat receiving surface and the cooling surface;
A cooling thermoelectric element disposed in direct contact with the cooling surface of the power generation thermoelectric element directly or indirectly through a heat medium; and
A constant temperature controller that controls the temperature of the cooling surface to maintain a predetermined temperature by energizing the thermoelectric element for cooling when a generated voltage is obtained from the thermoelectric element for power generation;
A fire detection unit for detecting a fire based on a power generation voltage from the thermoelectric element for power generation;
A heat sensor characterized in that is provided.
The heat sensor according to claim 1,
The constant temperature controller is
A temperature sensor for detecting the temperature on the cooling surface side of the thermoelectric element for power generation;
A power supply unit that outputs a predetermined power supply voltage when the generated voltage from the thermoelectric element for power generation reaches a predetermined voltage;
A feedback control unit that operates in response to supply of a power supply voltage from the power supply unit and controls the cooling thermoelectric element so as to keep the temperature of the cooling surface detected by the temperature sensor at a predetermined threshold temperature;
A heat sensor characterized in that is provided.
The heat sensor according to claim 1,
The constant temperature controller is
A temperature resistance element whose resistance value changes depending on the temperature disposed on the cooling surface side of the thermoelectric element for power generation;
When the power generation voltage from the power generation thermoelectric element reaches a predetermined voltage, a predetermined power supply voltage is supplied to the cooling thermoelectric element via the temperature resistance element to cool the cooling surface of the power generation thermoelectric element. A power supply unit,
A heat sensor characterized in that is provided.
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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