JPH0143263B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fire detection device for detecting fire in a thermostatic oven.

Various types of constant temperature chambers (chambers), such as low-temperature chambers, burn-in devices, aging devices, low-temperature (freezing) temperature chambers, and high-temperature temperature chambers, are often used for product development, initial defect inspection, and product storage. It's starting to look like this.

For example, in factories that produce electronic parts and equipment, products such as printed circuit boards and equipment mounted with newly developed IC parts or parts are manufactured at environmental temperatures ranging from a low temperature of around -20°C to a high temperature of around 150°C. The parts and products are placed in a constant temperature chamber called a variable low-temperature chamber, and the installed parts and products are energized to vary the environmental temperature in order to test their characteristics, usage conditions, and lifespan. In addition, the produced parts and products are placed in a constant temperature chamber called a burn-in device or an aging device, and electricity is applied to the set parts and products to age them at high temperatures of 50 to 150 degrees Celsius for several hours to several days. We strive to prevent defects after sales by stabilizing the initial characteristics of parts and products and inspecting for initial defects.

By the way, if a part or product that is being tested or aged in such a thermostatic chamber overheats abnormally due to a defect in the manufacturing process and starts to burn, the flames will spread to other parts and products housed in the thermostatic chamber, causing many problems. The parts and products of the machine are damaged, and even the thermostatic chamber is damaged, resulting in major damage. For this reason, early detection of fires in thermostatic chambers is desired. However, the temperature inside a thermostat varies over a wide range of temperatures, from below freezing to over 100°C, depending on the application, and the set temperature varies depending on the type of part or product. Fire detectors such as thermal, ionization, scattered light, dimming, and flame types cannot be used, leaving the area almost defenseless against fire.

In view of the above-mentioned points, this invention aims at a fire detection device for a thermostatic oven that can detect fires occurring in thermostatic ovens used at low or high temperatures at an early stage. A sampling chamber is set up separately from the thermostatic chamber, and the air inlet pipe of the sampling chamber is connected to the secondary side of the fan installed for air circulation inside the thermostatic chamber, and the air outlet tube is connected to the primary side of the fan. A pair of glass windows are provided facing each other in the sampling chamber, and a light emitting element of a dimming type smoke detector and the light emitted from this light emitting element are connected to one side of the pair of glass windows. A light transmitting section equipped with a lens that makes the light almost parallel to each other, and a light receiving section equipped with a photoelectric element and a lens that focuses the light from the light transmitting section on the photoelectric element on the other side of the glass window are respectively exposed from the outside. The present invention is characterized in that a space communicating with the outside air serving as a heat insulating layer is provided between each of the glass windows and each lens.

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a constant temperature bath for aging provided in a housing (not shown).This constant temperature bath 1 is surrounded by a wall 2 filled with a heat insulating material, etc. The circulating air is heated by a heater 4 and cooled by a cooler 5 to a predetermined temperature, for example, 80°C, and is then used for rectification. The flow is rectified by filters 6 ₁ and 6 ₂ and flows into tank 1.
flowing within. Reference numeral 7 denotes a smoke detection section provided outside the thermostatic oven 1, and the smoke detection section 7 is composed of a sampling chamber 8 that guides the air circulating inside the thermostatic oven 1 and a dimming type smoke sensor 9. The air inlet pipe 8 ₁ of the sampling chamber 8 is connected to the inside of the tank 1 on the secondary side of the circulation fan 3 of the thermostatic chamber 1, and the air outlet pipe 8 ₂ is connected to the tank 1 on the secondary side of the circulation fan 3 of the thermostatic chamber 1.
Connected to tank 1 on the next side. The sampling chamber 8 is also provided with a pair of glass windows 8 ₃ and 8 ₄ facing each other. The dimming type smoke detector 9 has a light emitting part 9 ₁ and a light receiving part 9 ₂ that are connected to the glass windows 8 ₃ and 8 ₄ by providing a space A as a heat insulating layer outside the glass windows 8 ₃ and 8 ₄ . It is attached to the sampling chamber 8 via a thermal insulator 10 so as to face it.

FIG. 2 shows an example of the specific structure of the smoke detection unit 7, in which the sampling chamber 8 is composed of a tubular or box-shaped housing extending coaxially with the optical axis L of the dimming type smoke detector 9. , openings are provided opposite to each other at both ends of the chamber 8,
Glass G is attached to each of these openings to form a pair of glass windows 8 ₃ and 8 ₄ . Note that the structure for attaching the glass G to the glass windows 8 ₃ and 8 ₄ is preferably a removable structure for maintenance reasons, and the glass G may be made of ordinary glass or heat-resistant glass, and the glass G may be attached to the glass windows 8 3 and 8 4 at a temperature that corresponds to the temperature of the air flowing through the sampling chamber 8. Just choose the appropriate one. Near both ends of the side wall of the sampling chamber 8, an air introduction pipe 8 ₁ connected to the secondary side of the circulation fan 3 of the constant temperature chamber 1 and an air outlet pipe 8 ₂ connected to the primary side are provided, respectively. .
The attenuation type smoke detector 9 also includes a light emitting part 91 having a light emitting element ₉₃ such as a light emitting diode, a light emitting lens ₉₄ , etc., and a solar light receiving part ₉₁ that receives the light emitted from the light emitting part ₉₁ . A photoelectric element ₉₅ such as a battery, a light receiving part _{92 having a light receiving lens 96 ,} etc. are connected to a space A communicating with the outside air, which serves as a thermal insulation layer, on the outside of the glass windows ₈₃ and ₈₄ of the sampling chamber 8, respectively. Open glass window 8
₃ and 8 ₄ , and is attached and fixed with screws 11 to a support 10 made of a thermally insulating synthetic resin or the like that supports the sampling chamber 8 .

Next, the effect will be explained.

Air in the thermostatic chamber 1 is circulated within the chamber 1 by a fan 3, and this circulating air is heated by a heater 4 and cooled by a cooler 5 to a predetermined set temperature.
For example, it is heated to 80℃. In this hot air flow, the pressure on the secondary side of the circulation fan 3 is higher than the pressure on the primary side. Due to the pressure difference between the secondary side and the primary side of the circulation fan 3, a part of the hot air flow flows into the sampling chamber 8 from the secondary side of the fan 3 through the introduction pipe ₈₁ . The hot air flow that has entered the sampling chamber 8 is sucked by the negative pressure on the primary side of the fan 3 and flows out into the tank 1 through the outlet pipe 8 ₂ . In this way, sampling chamber 8
Due to the pressure difference between the secondary side and the primary side of the circulation fan 3, a part of the hot air current circulating inside the thermostatic chamber 1 flows inside. Also, the light emitting part 9 of the dimming type smoke detector 9
₁ emits light continuously or intermittently toward the light receiving section ₉₂ . The light emitted from the light projector 9 ₁ passes through the glass window 8 ₃ and enters the sampling chamber 8.
The incident light passes through the sampling chamber 8 and the glass window 8 ₄ and is received by the light receiving section 9 ₂ .

By the way, if an aging component or product (not shown) housed in the thermostatic chamber 1 abnormally heats up due to a manufacturing defect and burns out, generating smoke, the hot air flow containing the smoke flows into the inlet pipe from the secondary side of the fan 3. 8
₁ into the sampling chamber 8, the inflowing smoke passes through the sampling chamber 8 and is discharged into the tank ₁ through the outlet pipe 82. The light transmitted into the sampling chamber 8 is attenuated by the smoke contained in the hot air flow passing through the sampling chamber 8, and the light receiving section 9 ₂
The amount of light received by the photoelectric element 95 decreases, and the output of the photoelectric element ₉₅ decreases. When the output of the photoelectric element ₉₅ falls below a predetermined value, a detection circuit (not shown) is activated, and the detector 9 transmits the fire signal to a fire receiver (not shown) or a thermostat 1 (not shown).
The signal is sent to the control panel of the vehicle to notify that a fire has occurred. Note that when the detector 9 detects a fire, a fire extinguisher may be controlled in conjunction with the fire extinguishing equipment to automatically release a fire extinguisher such as carbon dioxide into the thermostatic chamber 1.

In addition, in the case of constant temperature chambers such as low-temperature insulation chambers for storing chemicals, low-temperature chambers used for experiments, etc., the inlet pipe of the sampling chamber should be connected to the secondary side of the circulation fan, as in the above example. The outlet pipe is connected to the primary side of the circulation fan, and the low-temperature airflow of, for example, -10℃ or the high-temperature airflow of, for example, 100℃, circulating in the thermostatic chamber is guided to the sampling chamber by the pressure difference between the airflows, and the airflow is connected to the sampling chamber. Smoke contained in the airflow may be detected by a thermally insulated dimming type smoke detector. In addition, in dimming type smoke detectors, only the light emitting part and the light receiving part may be placed facing the sampling chamber, and the detection circuit part may be installed in the receiver or control panel. It is also possible to use a device with variable detection sensitivity. Furthermore, by covering the sampling chamber, air inlet pipe, and air outlet pipe with a heat insulating material, except for the glass window, the airflow flowing through the sampling chamber can be prevented from changing due to the influence of outside air. be able to.

According to this invention, the airflow circulating in the thermostatic chamber is guided to the sampling chamber having a pair of glass windows by using the pressure difference, and the smoke contained in the airflow flowing into the sampling chamber is removed from the outside of the sampling chamber. Since the light emitting part and the light receiving part of the dimming type smoke detector installed in a thermally insulated manner are used to monitor the smoke detector, fires that occur inside the thermostatic chamber can be detected with a simple configuration and a dimming type smoke detector. This has the effect of providing a constant temperature oven fire detection device that can reliably detect a smoke detector without being affected by temperature.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of a fire detection device for a thermostatic oven according to the present invention, and FIG. 2 is a sectional view of essential parts of an embodiment of a smoke detection section used in the fire detection device for a thermostatic oven of the invention. It is. 1... Constant temperature chamber, 3... Air circulation fan, 7...
...Smoke detection section, 8...Sampling chamber, 8 ₁ ...Air introduction pipe, 8 ₂ ...Air outlet pipe, 8 ₃ , 8 ₄ ...1
Pair of glass windows, 9... dimming type smoke detector, 9 ₁ ...
Light projecting section, 9 ₂ ... Light receiving section, A... Space.

Claims (1)

[Scope of Claims] 1. A sampling chamber is provided for introducing air in the thermostatic chamber, and an air introduction pipe of the sampling chamber is connected to the secondary side of a fan provided for air circulation in the thermostatic chamber, and an air outlet pipe is connected to the secondary side of a fan provided for air circulation within the thermostatic chamber. are connected to the primary side of the fan, and a pair of glass windows are provided in the sampling chamber facing each other, and a light emitting element of a dimming type smoke detector and a light emitting element of the dimming type smoke detector are connected to one of the pair of glass windows. A light receiving section including a light projecting section including a lens that makes the light emitted from the element substantially parallel, and a photoelectric element on the other side of the glass window and a lens that focuses the light from the light projecting section on the photoelectric element. 1. A fire detection device for a constant temperature oven, characterized in that the respective glass windows and lenses are provided with a space communicating with the outside air as a heat insulating layer between the glass windows and the lenses from the outside. 2 The sampling chamber is covered with a heat insulating material except for a pair of gas windows.
Fire detection device for thermostatic chambers as described in section. 3. A fire detection device for a thermostatic chamber according to claim 1 or 2, wherein the pair of glass windows of the sampling chamber are provided in a removable manner.