JPS5836049Y2 - temperature detector - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a temperature sensor in which the sensitivity of the detection element and the installation workability are improved.

As a temperature sensor that has a wider monitoring area than before, internal pressure is applied by fluid to the sensing element made of a thermoplastic tube, and when the tube softens as the ambient temperature rises, the internal pressure causes the tube to localize. There is a well-known temperature sensor which detects an increase in ambient temperature based on the drop in internal pressure that occurs when the tube expands and eventually ruptures.

In the detection element of this type of temperature detector, it takes time for the temperature to rise to the point where the plastic tube softens and melts, so it may take several hundred seconds after the ambient temperature reaches the temperature that should be detected as a fire condition. This causes a drop in internal pressure, causing a delay in activation, and the delay in response has become a problem for the detector.

In order to shorten the above delay time, it is possible to reduce the thickness of the plastic tube that is the sensing element, but since this plastic tube is constantly under internal pressure, it is in a state where stress in the circumferential direction, that is, hoop stress, is constantly applied. In order to withstand such hoop stress over a long period of time, stable fire monitoring must be performed over a long period of several years or more, and in order to withstand such hoop stress for a long period of time, it is essential that the plastic tube has a wall thickness that exceeds a certain level determined by its creep rupture characteristics.

For this reason, in conventional sensing elements of this type, the thick wall causes the sensing element itself to spring back, making it difficult to bend when installing the sensing element, and special holding tools are required to maintain the bent shape. there were.

In general, the hoop stress σ that acts on a cylindrical tube is expressed by the following formula, %, where the tube outer diameter is D (cm), the internal pressure is P (kg/-), and the tube wall thickness is d (crrL'l). As the wall thickness d decreases, the hoop stress increases, and as shown in Figure 1, as shown in Figure 1, the time it takes for the tube to break under normal monitoring conditions at the same internal pressure value, that is, the life span, shortens. .

FIG. 1 shows an example of a creep rupture curve of a low-density polyethylene tube, and shows that an increase in hoop stress leads to a shortened life.

Furthermore, if the wall thickness of the tube is too thin, the mechanical strength during handling will be reduced, making installation work difficult, and the wall thickness must be adequate in this respect as well.

This idea was made in view of the problems mentioned above, and the second
As schematically shown in the figure, a long flexible sensing element A to which internal pressure is applied by gas or liquid is connected to a detector body consisting of a pressure holding device B and a pressure sensing device C, and the sensing element In a temperature sensor that detects the ambient temperature of an abnormal location by detecting a pressure drop due to local thermal rupture of A temperature sensor characterized by using a composite tube in which a thin-walled metal tape is continuously combined in the length direction of the temperature-sensitive tube so that the metal tape forms continuous slits in the length direction of the temperature-sensitive tube. In order to increase the heat receiving efficiency on the surface, a metal tape with good thermal conductivity is attached closely to the thermosensitive tube that constitutes a thin sensing element that can withstand hoop stress, and the rigidity of this metal tape allows for detection. An object of the present invention is to provide a temperature sensor equipped with an improved sensing element that suppresses springback and has flexibility.

To explain this invention in detail together with the drawings of the embodiments, Fig. 3 is an explanatory diagram of the structure of the sensing element in the temperature sensor of the invention, and 1 is a temperature-sensitive tube made of thermoplastic resin such as polyethylene or polyvinyl chloride; Depending on the material selected, the tube 1 softens and even melts at a predetermined temperature.

A thin metal tape 2 made of a metal material with good thermal conductivity, such as aluminum, copper, or nickel silver, is tightly placed on the outer periphery of the temperature-sensitive tube 1, and the surface of the temperature-sensitive tube is covered between both edges of the metal tape 2. A slit 3 is formed through which the is exposed.

Both the metal tape 2 and the slit 3 are continuous in the length direction of the tube 1, and in the drawings of the embodiment, the slit 3 is formed in a straight line, but if it is continuous in the length direction of the tube 1, it has a positive strong wave shape or a rectangular wave shape. , or may be formed in a triangular wave shape.

Further, the metal tape 2 may be provided inside the tube 1.

The sensing element in the temperature sensor of this invention having such a configuration is used with a fluid such as N2 gas sealed in the temperature sensing tube 1 to apply internal pressure, and it is installed, for example, in a corner of the ceiling of a room. Conduct fire monitoring.

In this case, the rise in ambient temperature caused by the fire is efficiently received by the metal tape 2, and the temperature-sensitive tube 1 is softened by heat conduction from the metal tape 2.

The thermosensitive tube expands due to internal pressure at the slit 3 portion, and finally melts and bursts at the slit 3 portion.

In this case, a sudden drop in internal pressure is detected by a pressure detection device and a fire alarm is issued.

According to the temperature sensor of this invention, the sensing element effectively captures radiant heat and convective heat by attaching the metal tape and transmits it to the temperature-sensitive tube, so the operating time is shortened despite the wall thickness of the temperature-sensitive tube. Delays can be shortened, and the springback of the temperature-sensitive tube can be suppressed by the rigidity of the metal tape, making it easy to create bends, making it easy to bend during installation, and eliminating the need for separate restraints to maintain the bent shape. Many practical effects can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an example of the creep rupture characteristics of a low-density polyethylene tube, Fig. 2 is a functional schematic diagram of the temperature sensor of the present invention, and Fig. 3 is a partial perspective view showing an embodiment of the invention. be. 1...Thermosensitive tube, 2...Metal tape, 3...
Slint.

Claims (1)

[Scope of utility model registration request] A long flexible sensing element to which internal pressure is applied by gas or liquid is connected to a detector body consisting of a pressure holding device and a pressure sensing device, and detects a pressure drop due to local thermal rupture of the sensing element. In a temperature sensor that detects the ambient temperature of the abnormal location by using the flexible sensing element, a thin metal tape is continuously connected in the length direction of the temperature-sensitive tube that softens when heated to a predetermined temperature. A temperature sensor characterized by using a composite tube made of tape so that continuous slits are formed in the length direction of the temperature-sensitive tube.