JPS605430Y2 - Thermal fire detector - Google Patents

Description

[Detailed description of the invention] This invention connects the end faces of optical fibers installed at a predetermined distance in the sensor housing with a soft hollow pipe, and uses a heat-receiving response such as an inverted bimetal when heat from a fire is detected. This invention relates to a thermal fire detector that detects fire by crushing a soft hollow pipe by deforming its parts and blocking the propagation of light.

In conventional fire alarm systems, a fire detector is connected to a power signal line drawn out from a receiver, and a switch contact is closed when a change in physical phenomena such as heat or smoke due to a fire is detected. It is designed to send a fire detection signal to the receiver and receive and display a fire alarm.

By the way, in conventional fire detectors, 24 volts DC voltage is generally supplied from the receiver through the signal line that also serves as a power supply, so it is not suitable for use in, for example, places filled with explosive gas or explosion-proof areas where open flames are strictly prohibited. It is not possible to install fire detectors that require a power supply, and there are no other effective means of detecting fire.

Furthermore, conventional fire detectors that use signal line connections are susceptible to various types of induced noise, and malfunction of the fire alarm system due to this noise becomes a problem. A solution is needed.

The present invention was developed in view of the above, and has an essentially explosion-proof structure that does not require a power supply, has high fire detection sensitivity, and is furthermore safe and secure as it can completely eliminate the effects of various electrical noises. The purpose is to provide a thermal fire detector with excellent reliability.

FIG. 1 is an explanatory cross-sectional view showing one embodiment of the present invention.

First, to explain the configuration, reference numeral 1 is a sensor housing, and inside the sensor housing 1 there is an outbound optical fiber 2 that guides light from a light source provided on the receiver side, and an outbound optical fiber 2 that guides light from a light source provided on the receiver side. A return optical fiber 3 for outputting to the side or another sensor is drawn in, and a starting end face 3a of the return optical fiber 3 is provided at a predetermined distance from the terminal end face 2a of the outgoing optical fiber 2.

Between the terminal end face 2a of the outbound optical fiber 2 and the start end face 3a of the return optical fiber 3, a silicon rubber tube,
A soft hollow pipe 4 made of a soft material such as a Teflon rubber tube is connected, and the incident light Lt from the outgoing optical fiber 2 is incident on the incoming optical fiber 3 through the soft hollow pipe 4, and is sent out as received light Lr. are doing.

A shape-memory metal 6 formed in the shape of a coil spring that operates as a heat-receiving sensitive part is housed below the soft hollow pipe 4, and the heat collected by the heat-collecting plate 5 is transferred to the shape-memory metal 6. I'm trying to make it happen.

The shape memory metal 6 stores a shape that expands in the axial direction at the fire detection temperature, for example, 7.5°C, and at room temperature it contracts to the state shown in the figure, and at this room temperature, the deformation force in the axial direction is Nothing has happened.

Next, the operation of the embodiment shown in FIG. 1 will be explained.

First, in the steady state monitoring state, the shape memory metal 6 has a contracted shape as shown in FIG. The signal enters the optical fiber 3 for the return trip through the optical fiber 3, and is sent to the receiver side or another sensor.

Next, if the shape memory metal 6 is heated to a predetermined temperature at which shape memory is performed due to a fire, the shape memory metal 6 expands into the memorized shape and crushes the soft hollow pipe 4, as shown in FIG.

Due to the collapse of the soft hollow pipe 4, the incident light Lt that enters the soft hollow pipe 4 via the outgoing optical fiber 2 is transmitted to the soft hollow pipe 4 that has been crushed due to the expansion of the shape memory metal 6.
, and the propagation of light to the return optical fiber 3 is blocked.

Therefore, by detecting the interruption of the light on the receiver side into which the light from the return optical fiber 3 is incident, it is determined that a fire has been detected, and a fire alarm is displayed.

FIG. 3 is an explanatory cross-sectional view showing another embodiment of the present invention.

This embodiment is characterized by using a bimetal that deforms due to thermal expansion when heat from a fire is detected as the heat-receiving response section.

That is, a soft hollow pipe 4 connecting the terminal end face 2a of the outbound optical fiber 2 and the start end face 3a of the return optical fiber 3 is supported by a bimetal 7 that is heated and deformed by the heat collected by the heat collecting plate 5. When a fire is detected, as shown in Fig. 4, the bimetal 7 bends upward due to thermal expansion, pushing up the pressing pin 8 and pushing up the soft hollow pipe. 4 is crushed to block light from the outbound optical fiber 2 to the return optical fiber 3 to detect a fire.

Further, as a feature of the fire detector of the present invention as clarified in the above embodiments, the end face of the optical fiber is isolated from the outside by the connection of the soft hollow pipe 4, so that the adhesion of dust etc. to the end face of the optical fiber can be prevented. , it is possible to reliably prevent an increase in optical loss due to the end face of the optical fiber becoming dirty during use.

In addition, since it does not use a reflection method, the loss of light passing through the fire detector is extremely small, and compared to a fire detector using an optical fiber that uses a reflection method, the distance between the receiver and the fire detector is reduced. This has the advantage that the transmission distance can be increased and the number of fire detectors connected in series to one optical transmission line can be increased.

Furthermore, by forming the inner surface of the hollow pipe into a mirror surface,
Light loss in the hollow pipe section can be further reduced.

In all of the above embodiments, the hollow pipe is completely crushed in the event of a fire, and the light is completely blocked. It may also be configured to detect a fire.

As explained above, according to the present invention, the terminal end surface of the outgoing optical fiber and the starting end surface of the returning optical fiber are opposed to each other with a predetermined distance apart in the sensor housing, and the terminal end surface and the starting end surface of both optical fibers are A hollow pipe made of a soft material is used to connect the space between the two, and when heat from a fire is detected, the heat-receiving/responsive part deforms, crushing the hollow pipe and cutting off the propagation of light, thereby detecting a fire. , there is no need to supply power to the fire detector, so it has an essentially explosion-proof structure that can be installed as is in areas filled with explosion-proof gas, etc., and there are no restrictions on the installation location, and it eliminates induced noise etc. It has a simple structure that allows fire detection by simply crushing a soft hollow pipe installed inside the sensor housing by thermal deformation of a heat-receiving part such as a bimetal. Therefore, when optical fiber cables become popular, it will be possible to significantly reduce equipment costs, and since there are no parts that will deteriorate over time, excellent durability can be obtained.

Furthermore, by forming the hollow pipe with a soft material having elasticity, the restoring force can be increased, and the durability can be further improved.

On the other hand, since the end face of the optical fiber inside the sensor is covered with a soft hollow pipe, the end face of the optical fiber is prevented from becoming dirty due to adhesion of dust, etc., and there is no risk of increased transmission loss even after long-term use. Furthermore, since it is not a reflection method, the transmission loss of light passing through the detector is extremely small, and the transmission distance of the optical transmission line from the receiver to the fire detector can be lengthened, and each line can be connected in series. Another advantage is that the number of sensors can be increased.

[Brief explanation of the drawing]

FIG. 1 is an explanatory cross-sectional view showing one embodiment of the present invention, FIG. 2 is an explanatory cross-sectional view showing the operating state of the embodiment of the present invention, and FIG.
The figure is an explanatory cross-sectional view showing another embodiment of the present invention, and FIG. 4 is an explanatory cross-sectional view showing the operating state of the embodiment of FIG. 3. 1...Sensor housing, 2...Outbound optical fiber 2
a... Termination surface, 3... Return path optical fiber, 3a...
... Starting end surface, 4... Soft hollow pipe, 5... Heat collecting plate, 6... Shape description tM metal, 7... Bimetal, 8...
...Press pin.

Claims (1)

[Scope of utility model registration request] Inside the sensor housing, the end face of the outbound optical fiber and the start end face of the return optical fiber are placed opposite to each other with a predetermined distance apart, and the end face and start end face of both optical fibers are connected by a hollow pipe made of a soft material. . A thermal fire detector, characterized in that the hollow pipe is collapsed by deformation of the heat-receiving response part when heat from a fire is detected.