JPH0672809B2 - Thermal detector - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting a thermal state of an environment in an air conditioner that provides a comfortable environment for humans.

2. Description of the Related Art A configuration considered prior to the present invention will be described with reference to FIGS. In FIG. 5, reference numeral 1 denotes a heating element using a thermistor. As shown in detail in the sectional view of FIG. 6, a cover 2 made of polyethylene resin that transmits radiant heat is provided outside the heating element 1 and Cover 2
An opening 3 and a supporting portion 4 are provided in order to attenuate the air flow and guide it around the heat generating element 1. The heating element 1 is controlled by the control means 5 to always generate heat at a constant temperature. At this time, the values of the convective heat transfer coefficient and the radiant heat transfer coefficient of the heating element 1 are substantially the same as those of the human body by the cover 2. Since they are equivalent, the determination means 6 can obtain information corresponding to the thermal sensation of the human body from the signal of the control load of the control means 5.

Problems to be Solved by the Invention However, in the above-mentioned configuration, since the thermistor is used as the heating element, the size and shape of the heating element are restricted. In particular, in order to match the sensitivity to air flow with the human body, it is necessary to reduce the convective heat transfer coefficient of the heating element, and for that purpose, the size of the element is increased.
Increase the size of the cover. A method of reducing the area of the cover opening is conceivable. However, in the above configuration, the methods of and are adopted, which causes an increase in the size of the cover, or the rate of reducing the wind velocity reaching the heating element is large. In the region, there is a problem that it is difficult to obtain the desired performance, that is, the sensitivity of the air flow while reducing the convective heat transfer coefficient.

The present invention solves the above-mentioned conventional problems. By maintaining a high productivity and a low price with a small number of parts and a simple structure, it is possible to reduce the size of the detection part and improve the detection performance. While making it easy to incorporate
An object of the present invention is to provide a comfortable warm space by controlling the air conditioner more finely than in the past based on the information corresponding to the thermal sensation of the human body.

Means for Solving the Problems In order to solve the above problems, the heat detection device of the present invention is
A heating element made of a substance whose electric resistance value changes according to its own temperature, a cap surrounding the heating element, and a cover surrounding the cap for transmitting radiant heat to the cap and reducing air flow. And a control means for maintaining the heating element at a constant temperature, and a judgment for judging the thermal state of the environment from a change in the power supplied from the control means to the heating element in order to keep the temperature of the heating element constant. It is configured by means.

Function In the present invention, by the above-mentioned configuration, the heating element generates heat, and radiant heat is exchanged between the surrounding object, solar radiation and the cap surface through the cover, and convective heat exchange is performed with the ambient air. In addition to the reduction of the convective heat transfer coefficient due to the attenuation of the air flow by the effect of the size and shape of the cap, the ratio of the convective heat transfer and the radiant heat transfer between the heat generating element and the surrounding environment can be roughly matched with that of the human body. Therefore, the magnitude of the load for maintaining the heating element at a constant temperature by the control means is obtained corresponding to the load for maintaining the body temperature of the human body constant. Since this can be taken out as an electric signal and the thermal sensation of the human body can be judged from this output, a comfortable space can be easily realized by controlling the air conditioner based on this judgment.

Embodiments Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a block diagram of a heat detection device of the present invention. Reference numeral 1 denotes a heating element using a thermistor. A cylindrical cap 7 made of aluminum is provided around the heating element 1, and a resin 8 having an electrically insulating property is provided in a gap between the heating element 1 and the cap 7. Filling. A spherical cover 2 formed of a polyethylene resin that surrounds the cap 7 and transmits radiant heat is provided, and the cover 2 has an opening 3 for attenuating the air flow and guiding the air around the heat generating element 1. Are evenly formed. The heating element 1 is controlled by the control means 5 so as to always generate heat at a constant temperature, and the determination means 6 can obtain information corresponding to the thermal sensation of the human body from the signal of the control load of the control means 5 at this time. FIG. 2 is a partially cutaway perspective view showing the configuration of the heating element 1, the cap 7 and the resin 8.

FIG. 3 shows an embodiment of the control means. The heating element 1, the operational amplifier 8, the fixed resistor 9, the fixed resistor 10,
With the fixed resistor 11, the temperature of the heating element 1 is controlled to be constant. When the circuit is operated, the heating element 1
Heats up to a certain temperature Tth determined by the resistance values of the fixed resistor 9, the fixed resistor 10, and the fixed resistor 11, where any of the ambient temperature, air flow, and radiant temperature changes. Then, when the temperature of the heating element is lowered via the cap 7, the resistance of the heating element 1 which is a thermistor rises and the potential at the point b rises. The potential difference is amplified and the potential at point c rises, and as a result, the current flowing through the heating element 1 increases. Due to this increase in current, the amount of heat generated by the heating element 1 increases, the temperature of the heating element 1 rises, and the temperature is stabilized at the original temperature Tth. At this time, the electric potential at the point b is taken out to the control means 5 and the following processing is performed. The heat balance between the surface of the heating element 1 and the environment is expressed by the following equation.

Q = α _c (T _s −T _a ) + α _r (T _s −T _r ) ... (1) However, Q: heat radiation amount per unit surface area of the cap (load α for controlling the temperature of the heating element to be constant) _c : Convective heat transfer coefficient between the cap surface and the environment T _s : Temperature of the cap surface _Ta : Temperature α _r : Radiant heat transfer coefficient between the cap and the environment T _r : Ambient radiant temperature Here, heat transfer to the material of the cap 7 The temperature of the surface of the heating element 1 is increased by using aluminum having a high rate.
Since the temperature difference between the Tth and the surface temperature T _s of the cap 7 is in a range that can be ignored at normal temperature, considered as follows Tth = T _c. The radiant heat transfer coefficient α _{r on the} surface of the cap 7 is determined by the ambient radiant temperature, the surface temperature of the cap 7 and the emissivity of the surface of the cap 7. It is possible to match. Diameter and thickness of the cover 2, the opening 3
And the diameter and length of the cylindrical cap are set so that the convective heat transfer coefficient α _c of the cap 1 is slightly lower than the average convective heat transfer coefficient of the human body. This is to correct the decrease in the radiant heat transfer coefficient due to the radiant transmittance of the cover. The thermal load to heat the heating element 1 obtained in this way has a high correlation with the load required to maintain the body temperature in the same environment. In advance, the judgment means 6 stores the relationship between the load signal obtained by the control means 5 and the thermal sensation of the human body in the form of a mathematical expression or a table, as shown in FIG. 4, in the ROM of the one-chip microcomputer. By controlling the air conditioning equipment so that the sense becomes neutral, a comfortable environment is always maintained.

In the above structure, the convective heat transfer coefficient can be reduced and the response time constant can be suppressed to a small value with a simple structure in which the heating element is covered with an aluminum cap having high thermal conductivity. In addition, since the heat capacity is small, the power consumption of the circuit can be reduced, so that there is an effect that the configuration driven by a battery is sufficiently possible.

Although aluminum is used as the material of the cap 7 in this embodiment, it is also possible to use other materials having high thermal conductivity such as copper and titanium. Further, although the resin is used as the filling material between the cap 7 and the heat generating element 1, a ceramic such as magnesium oxide or aluminum nitride, which has electrical insulation and has a large thermal conductivity, may be used. The shape of the cap 7 is also cylindrical in the present embodiment, but the same effect can be obtained with a prism, and even in the case of a spherical shape, the increase in the convective heat transfer coefficient due to the spherical shape increases the diameter of the cover 2. It can be used by supplementing by increasing.

Polyethylene resin was used as the material of the cover, but it is also possible to use silicon that transmits radiation well.

EFFECTS OF THE INVENTION As described above, according to the heat detection device of the present invention, the following effects can be obtained.

(1) With a cover that transmits radiant heat and reduces the air flow and a cap that covers the heating element, it is possible to make the ratio of convection and radiant heat transfer coefficient of the cap approximately equal to the value of the human body with a small cover shape. Since the heating element is configured to be maintained at a constant temperature, a high correlation can be obtained between the magnitude of the load and the thermal sensation of the human body, and optimal spatial equipment control can be performed.

(2) Since the structure is simple, high performance can be obtained at a low cost with a small number of parts, and therefore it is easy to manufacture and has a wide range of applications as a sensor for heating and cooling equipment.

[Brief description of drawings]

FIG. 1 is a configuration diagram including a partially cutaway perspective view of a heat detection device according to an embodiment of the present invention, FIG. 2 is a partially cutaway perspective view of a main portion of the device, and FIG. 3 is a control means of the device. Circuit diagram of the fourth
FIG. 5 is a characteristic diagram showing the contents of the judgment made by the judgment means of the same device.
FIG. 6 is a block diagram showing a configuration of a heat detection device considered prior to the present invention, and FIG. 6 is a partially cutaway perspective view showing a configuration of a heating element and a cover of the heat detection device considered prior to the present invention. is there. 1 ... Heating element, 2 ... Cover, 5 ... Control means, 6 ...
… Judgment means, 7… Cap.

Claims (1)

[Claims] 1. A heating element made of a substance whose electric resistance value changes according to its own temperature, a cap provided to surround the heating element, a radiant heat to the cap provided to surround the cap and transmitting the radiant heat to the cap. A cover for reducing the air flow, a control means for maintaining the heating element at a constant temperature,
A heat detection device comprising: a determination unit that determines the heat state of the environment based on a change in the electric power supplied from the control unit to the heat element in order to keep the temperature of the heat element constant.