JPH03274336A - Automatic ventilating fan - Google Patents

Abstract

PURPOSE:To rapidly react to indoor contaminated gas, to accurately detect contaminated gas without being influenced by operation of a ventilating fan and entrance of outside air by providing a gas sensor having an oxide semiconductor and a heater and a blower device to feed a constantly specified amount of air to the gas sensor. CONSTITUTION:Since a constantly specified amount of indoor air is fed to a gas sensor 6 with the aid of a blower device 4, there is always no difference between the temperature of the periphery of the gas sensor 6 and an indoor air temperature, and temperature is prevented from reduction due to operation of a ventilating fan and entrance of outside air. Thereby, the gas sensor 6 accurately detects contamination of indoor air, and useful operation is practicable. Since air around the ventilating fan is always induced to the gas sensor 6 with the aid of the blower device 4, a detecting time for reducing gas is shortened and reducing gas can be prevented from diffusion by outside air.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an automatic ventilation fan that automatically exhausts indoor dirty air.

2. Prior Art Conventionally, this type of automatic ventilation fan has generally been used as shown in Figs. 3 and 4.
It was as shown in the figure. That is, the main body 101 has an opening 102 for suction on the indoor side and an outlet 10 for discharging on the side.
It is attached to the ceiling with a frame body with 3. This main body 1
A casing 105 equipped with a fan motor 104 for blowing air is fixed inside the housing 01. The gas sensor 106 includes an oxide semiconductor 107 that reacts with a reducing gas and a heater 108 that heats the oxide semiconductor 107. A detection circuit 109 drives a fan motor 104 for blowing air according to the output signal of the gas sensor 106. So, gas sensor 10
6 and is housed in a case 111 and installed near the opening 102. Further, the duct 110 communicates with the outlet 103 and the outdoors, and the louver 112 is locked by a spring 113.

Problems to be Solved by the Invention In such a conventional configuration, the ambient temperature of the gas sensor 106 becomes several d below the indoor air temperature due to the heat generated by the heater 108.
It stabilizes when the EG is high.

At this time, the oxide semiconductor 107 in the gas sensor 106 detects reducing gas due to smoking etc. of the person in the room, and the detection circuit 1
When the fan motor 104 starts operating at 09 and ventilation begins, the ambient temperature around the gas sensor 106 rapidly decreases due to the inflow of room air. The reaction characteristics of the oxide semiconductor 107 depend on the ambient temperature, and as the ambient temperature decreases, the degree of reactivity increases, causing the oxide semiconductor to behave as if it has come into contact with a larger amount of reducing gas than it actually was, and the indoor air becomes cleaner. However, there is a problem in that the fan motor 104 continues to be operated for a longer time than necessary. Furthermore, since the main body 101 communicates with the outside air through the duct 110, outdoor air may enter the main body 101 due to outside wind, but this outside air may diffuse or push the reducing gas in the indoor air. Gas sensor 1 may be returned
06 and the fan motor 104 is not operated, or if the temperature of the outside air is significantly lower than the indoor air during winter, the outside air may be cold even though both the outside air and the indoor air are clean. Due to the invasion of
There is a problem in that the ambient temperature of the gas sensor 106 rapidly decreases and the fan motor 104 starts operating, which is very likely to cause malfunction.

Furthermore, in a large room, it takes a long time for the reducing gas to reach the gas sensor 106, causing a problem in that the start of operation of the fan motor 104 is delayed.

The present invention solves these problems, and prevents the ventilation fan from operating for an unnecessarily long time due to the temperature dependence of the gas sensor due to the temperature around the gas sensor dropping when the ventilation fan is in operation, and prevents outside wind from entering. The purpose of this system is to prevent large delays in the operation of the ventilation fan and malfunctions during cleanliness, and to enable the ventilation fan to operate quickly even in large rooms.

Means for Solving the Problems In order to solve the problems, the present invention provides a gas sensor including an oxide semiconductor and a heater, a blower device that always blows a certain amount of air to the gas sensor, and a fan motor for ventilation. The automatic ventilation fan includes a detection circuit that drives the fan motor in response to the detection output of the gas sensor.

With this configuration, a certain amount of indoor air is always blown to the gas sensor by the blower, so the temperature around the gas sensor is always the same as the indoor air temperature, and there is no temperature drop due to ventilation fan operation or outside wind intrusion. Since this does not occur, the gas sensor accurately detects indoor air pollution and enables efficient operation. Furthermore, since the gas sensor is constantly drawn in with the air around the ventilation fan by the blower, the detection time for reducing gas is accelerated, and the diffusion of reducing gas due to outside wind can be prevented.

EXAMPLE An example of the present invention will be described below with reference to FIGS. 1 and 2.

The main body 1 is attached to the ceiling with a frame body having an opening 2 for suction on the indoor side and an outlet 3 for discharging on the side. A casing 5 equipped with a fan motor 4 for ventilation is fixed within the main body 1. The gas sensor 6 includes an oxide semiconductor 7 that reacts with reducing gas and a heater 8 that heats the oxide semiconductor 7. A blower device 14 that always blows a certain amount of indoor air is installed in the vicinity of the gas sensor 6. The detection circuit 9 drives the fan motor 4 for ventilation according to the output signal of the gas sensor 6, and is housed in the case 11 together with the gas sensor 6 and installed near the opening 2. Further, the duct 10 communicates the outlet 3 with the outside, and the louver 12 is held by a spring 13.

In the above case, the oxide semiconductor 7 of the gas sensor 6 is heated by the heater 8, and a constant amount of indoor air is always blown to the gas sensor 6 by the blower 14, so that the ambient temperature is kept constant. When reducing gas is generated due to smoking or the like by a person in the room, the oxide semiconductor 7 reacts with the reducing gas that is quickly induced by the blower 1114, and an output signal from the gas sensor 6 is output. The detection circuit 9 drives the fan motor 4 based on this output signal, and blows the dirty air inside the room through the opening 2. Outlet 3. The air is exhausted to the outside through the duct 10. At this time, indoor air passes near the gas sensor 6, but the ambient temperature is always the same as the indoor air due to the air blowing from the air blower 14, so it does not change, and the reaction characteristics of the oxide semiconductor 7 change depending on the temperature change. will never change. This also applies to the outside wind that enters from outside, and the ambient temperature of the gas sensor 6 is kept constant. When the indoor air becomes clean, the output signal of the gas sensor 6 is stopped, and the fan motor 4 is stopped.

As described above, according to this embodiment, since a fixed amount of indoor air is always blown to the gas sensor 6 by the blower 14, the reaction characteristics of the gas sensor 6 will not change depending on the operation of the fan motor 4 or the outside wind. The detection passage 9 allows the fan motor 4 to be set to zero.
NOFF can be performed, reducing gas can be quickly induced by the blower device 14, and the operation start time can be shortened.

Effects of the Invention As is clear from the description of the embodiments above, according to the present invention, by blowing air around the gas sensor, it quickly reacts to indoor 19-staining gas and prevents the operation of ventilation fans and the intrusion of outside wind. The effect is that contaminated gas can be accurately detected without being affected by wasteful ventilation.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an automatic ventilation fan according to an embodiment of the present invention;
Figure 2 is an enlarged sectional view of the gas sensor of the automatic ventilation fan, Figure 3
The figure is a sectional view of a conventional automatic ventilation fan, and FIG. 4 is an enlarged sectional view of a gas sensor of the conventional automatic ventilation fan. 4...Fan motor, 6...Gas sensor, 7...Oxide semiconductor, 8...Heater, 9...Detection circuit.

Claims (1)

[Claims] A gas sensor including an oxide semiconductor and a heater, a blower that always blows a fixed amount of air to the gas sensor, a fan motor for ventilation, and a detection circuit that drives the fan heater in response to the detection output of the gas sensor. Automatic ventilation fan consisting of.