JPH057674Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to an ionization type smoke detector.

[Background Art] Ionization type smoke detectors have been provided in the past, and are disclosed in U.S. Reissue Patent No. 30323 and the like. This smoke detector basically has the following configuration. That is, an internal electrode having a chamber inside the external electrode, an internal electrode having a radiation source inside the chamber, and an intermediate electrode having at least one through hole through which radiation from the radiation source can pass. It is. However, the air inside the chamber is ionized by radiation, and when smoke particles are introduced into the external electrode, the ions contained in the air are absorbed by the smoke particles, which also interferes with the ionization of the air. . This reduces the ionic current compared to when no smoke is present, and if a voltage is applied between the inner and outer electrodes, the potential of the intermediate electrode will change as the ionic current changes. This results in a large change, which allows the presence of smoke to be detected.

By the way, this kind of conventional smoke detector has a shape in which a shield case is further provided outside the external electrode, and there is a problem that the smoke detector becomes large in size.

[Purpose of the invention] The present invention has been made in view of the above points, and its purpose is to electrically connect the external electrode and the shield case so that the external electrode can also be used as a shield. Another object of the present invention is to provide an ionization type smoke detector that has a reduced number of component parts and is miniaturized.

[Disclosure of the invention] The ionization smoke detector according to the invention includes an internal electrode that holds a radiation source, and an external electrode that has an inlet hole that surrounds the outside of the internal electrode and introduces smoke into the inside. an intermediate electrode having at least one through hole disposed between the inner electrode and the outer electrode through which radiation from the radiation source can pass;
In the sensor unit of an ionization smoke detector, which detects smoke by detecting changes in ion current when smoke comes into contact with gas ionized in the external electrode, an internal electrode, an intermediate electrode, and an external electrode are used. A circuit board is placed between the electrode base to be held, the circuit board on which the circuit section is mounted and placed on the opposite side of the electrode base from the external electrode, and the electrode board formed in a cylindrical shape with a bottom. The external electrode is formed into a cylindrical shape with a bottom, and the opening edge of one of the shield case and the external electrode has a concave and convex surface that engages with a clip hole formed in the other peripheral wall from the inside. A clip piece with a convex portion that protrudes is provided, and when the shield case and the external electrode are connected with their opening surfaces facing each other, the external electrode and the shield case are connected mechanically and electrically through the clip piece. By electrically coupling the external electrode and the shield case, the external electrode also serves as a shield. In addition, the shield case and the external electrode are both formed in a cylindrical shape with a bottom and are coupled with their opening surfaces facing each other, and at the coupling site, a clip hole provided in one peripheral wall has a clip protruding from the edge of the other opening. Since the protrusions of the clip piece are engaged from the inside, the shield case and the external electrode can be easily attached and detached.Moreover, the shield case and the external electrode can be easily connected without applying external force to the protrusion of the clip piece. Since it does not fall off, even if it falls off during a fire, the radiation source will not be dissipated.

(Example) As shown in FIG. 1, the case 10 is formed into a cylindrical shape, including a bottomed cylindrical body 11 whose upper surface is closed, and a protective cover 12 that is fitted onto the lower surface of the body 11. Ru. Furthermore, the protective cover 12 includes a cylindrical windproof cover 13 that is bonded to the body 11 by adhesive or heat bonding, an insect net 14 that covers the side surface of the windproof cover 13, and a cap that closes the lower end surface of the windproof cover 13. 15. body 1
1. Both the windproof cover 13 and the cap 15 are made of synthetic resin molded products. A pair of mounting pieces 11b extend around the upper end of the body 11. The windproof cover 13 has an introduction hole 13a formed around the entire circumference thereof, and the insect net 14 is disposed so as to cover the entire surface of the introduction hole 13a. The insect screen 14 is formed by punching or etching a sheet metal to have a mesh shape that prevents small insects from entering the case 10 through the introduction hole 13a. Also,
The windproof cover 13 has a through hole 1 that passes through the top and bottom at the appropriate place.
3b is formed, and one end of this through hole 13b is open facing the outer surface of the case 10.

An ionization type smoke sensor is built into the case 10. This smoke sensor includes an internal electrode 22 holding a radiation source 21, an external electrode 23 disposed to cover the internal electrode 22, and a through hole 24a through which radiation emitted from the radiation source 21 passes.
The intermediate electrode 24 is formed with at least one
It is equipped with an internal electrode 22, an external electrode 2
3. The intermediate electrode 24 is mounted on an electrode base 25 made of an insulating material such as synthetic resin. Internal electrode 2
2 consists of a board part 22a formed of a sheet metal and a cover part 22b formed of a sheet metal and coupled to the board part 22a in a fitted manner.
The radiation source 21 is sandwiched between the cover portion 2a and the cover portion 22b. A terminal piece 22c is provided on the substrate portion 22a. A transmission window hole 22d for transmitting radiation from the radiation source 21 is formed in the cover portion 22b. On the other hand, the external electrode 23 is formed of sheet metal into a closed-bottomed cylindrical shape with a flange 23a formed on the upper edge, and has an introduction hole extending almost all the way around the side circumferential surface. 23b is formed. Here, the introduction hole 23b is set to a size that prevents the internal electrode 22 from scattering outward from the external electrode 23.
A plurality of clip pieces 23c are provided upwardly projecting at appropriate positions on the outer periphery of the flange 23a, and terminal pieces 23d are cut and raised at other parts of the flange 23a. Furthermore, a notch 23e is formed at one location of the flange 23a, and this notch 23e is formed to correspond to the through hole 13b of the windproof cover 13. The intermediate electrode 24 is formed into a disk shape from a sheet metal, and a through hole 24a through which radiation passes is formed in the center corresponding to the internal electrode 22.
Further, the terminal piece 24b is formed by cutting and bending. By the way, the electrode base 25 is formed into a disk shape, and a cylindrical partition wall 25 is provided at the center of the lower surface of the electrode base 25.
a stands upright, and the intermediate electrode 24 is housed in a portion surrounded by the partition wall 25a. Further, an upwardly recessed storage recess 25b is formed in the center of the portion surrounded by the partition wall 25a, and the internal electrode 22 is accommodated in this storage recess 25b. However, terminal insertion holes 25c are formed at appropriate locations on the bottom surface of the storage recess 25b, inside the partition wall 25a, and outside the partition wall 25a so as to vertically penetrate through the electrode substrate 25. Each terminal piece 22c, 24b, 23d of the external electrode 23 is inserted through the terminal piece. Further, a plurality of pins 25f are protruded from the lower surface of the electrode substrate 25, and these pins 25f are inserted into pin holes 23f and 24c formed in the external electrode 23 and the intermediate electrode 24, respectively, and heated. By crushing the external electrode 23
and an intermediate electrode 24 are fixed to an electrode substrate 25. A notch 25d is formed at a suitable location on the circumference of the electrode substrate 25, and this notch 25d
are formed to correspond to the notch 23e of the external electrode 23 and the through hole 13e of the windproof cover 13. Further, a plurality of legs 25e are provided protruding from the upper surface of the electrode substrate 25.

In this way, the air between the external electrode 23, the intermediate electrode 24, and the internal electrode 22 is ionized by the radiation from the internal electrode 22 mounted on the electrode substrate 25, and the air between the external electrode 23, the intermediate electrode 24, and the internal electrode 22 is ionized. When smoke is introduced into the electrode 23, the ionic current changes due to the smoke coming into contact with ionized air, and as a result, the potential of the intermediate electrode 24 changes, making it possible to detect the presence of smoke.

Changes in the ion current are detected by a detection circuit mounted on the printed circuit board 26. The printed circuit board 26 is housed in a cylindrical shield case 27 made of sheet metal and having a closed top and a closed bottom. A light emitting diode 26a is mounted on the periphery of the printed circuit board 26 for checking the operating state, and this light emitting diode 26a is connected to the notch 23.
e, 25d, and is inserted into the through hole 13b and exposed to the outside. Therefore,
Whether the sensor is operating normally can be confirmed by the blinking state of the light emitting diode 26a. The detection circuit mounted on the printed circuit board 26 includes an internal electrode 22, an external electrode 23, and an intermediate electrode 24.
The respective terminal pieces 22c, 23d, and 24b are connected and fixed by soldering. Further, between the printed circuit board 26 and the electrode substrate 25, there are legs 2 protruding from the electrode substrate 25.
5e. Insulation between the back surface of the printed circuit board 25 and the bottom surface of the shield case 27 can be achieved by interposing an insulating sheet between the two, or by interposing an insulating sheet between the two.
Alternatively, the printed circuit board 25 can be attached to the shield case 27.
This is done by holding it so that it floats from the bottom. A clip hole 27b that engages with a clip piece 23c formed on the external electrode 23 is formed at a suitable location on the peripheral wall of the shield case 27, so that the middle part of the clip piece 23c is made to protrude outward. The curved convex portion is inserted into the clip hole 2.
By engaging 7b from the inside, the electrode section and the circuit section are surrounded by the external electrode 23 and the shield case 27, and the whole is made into a unit. In other words, the smoke sensor can be constructed simply by placing the components unitized in this way into the case 10, making the assembly work extremely easy. Furthermore, by engaging the clip piece 23c and the clip hole 27b, the external electrode 23 and the shield case 27 are electrically coupled, and the external electrode 23 can also be used as a shield, which is better than the conventional case. There is no need for a shield case that covers the outside of the external electrode 23, resulting in a reduction in the number of parts and storage space. Moreover, since the shield case 27 and the external electrode 23 are connected by the uneven engagement between the clip piece 23c and the clip hole 27b, the shield case 27 and the external electrode 23 are connected during assembly.
3 can be combined in a short time, and the shield case 27 and the external electrode 23 can be easily separated by pressing the convex part of the clip piece 23c from the outside, making it easy to remove the radiation source after a fire. can be easily done. A lead wire 26b for connecting to an external circuit is protruded from the top surface of the printed circuit board 26, and the lead wire 26b is inserted into a feedthrough capacitor 27a provided on the bottom surface of the shield case 27 and soldered. It's summery. on the other hand,
A cylindrical terminal pin 11a is insert-molded in the body 11 constituting the case 10 at a position corresponding to the feedthrough capacitor 27a provided in the shield case 27, and the lead wire 26b is inserted into the terminal pin 11a. A lead wire 26 is connected to the tip of the terminal pin 11a by soldering or spin processing.

Incidentally, since the case 10 is made of synthetic resin, the case 10 may melt in the event of a fire or the like, and the electrode portion may fall off from the case 10. However, in this embodiment, the external electrode 23
and the shield case 27 are combined, and the internal electrode 22 is disposed therein, and the introduction hole 23b through which smoke is introduced into the external electrode 23 is set smaller than the internal electrode 22. Therefore, even if the electrode part falls off from the case 10, the internal electrode 22 holding the radiation source 21 will not fly out, making it easy to recover the radiation source 21 and prevent the loss of the radiation source, which is a dangerous substance. It is possible to prevent this.

Sensor unit A formed as above
is used with a cover C attached to a base B fixed to a ceiling or the like as shown in FIG. That is, the base B has an opening 41 in the center into which the upper end of the sensor unit A can be inserted. A fitting groove 41b running in the circumferential direction is formed. The end of the fitting groove 41b is open at the ear hole 41a. Furthermore, an electrode (not shown) connected to the terminal pin 11a is provided within the base B. However, when the mounting piece 11b is inserted into the ear hole 41a and the sensor unit A is rotated along the fitting groove 41a, the mounting piece 11b fits into the fitting groove 41a and the sensor unit A is attached to the base B. It will be done. Further, the cover C has a claw (not shown) on the inner circumferential surface of the upper end, and this claw is attached to the cover B.
The cover C is attached to the base B by engaging with a hook hole 41c formed around the periphery of the cover C. It goes without saying that the cover C is also formed with an opening 42a into which the sensor unit A is inserted. In this way, since the sensor unit A and the cover C are separately attached to the base B, there is an advantage that the range of design choices for the sensor unit A and the cover C is widened. Furthermore, by housing various functional units within the cover C, various functions can be added to the sensor unit A.

[Effects of the invention] As described above, the present invention includes an internal electrode that holds a radiation source, an external electrode that is arranged to surround the outside of the internal electrode and has an introduction hole that introduces smoke into the inside. an intermediate electrode disposed between the inner electrode and the outer electrode and having at least one through hole through which radiation from the radiation source can pass, the smoke coming into contact with the ionized gas within the outer electrode; In the sensor unit of an ionization smoke detector that detects smoke by detecting changes in ion current when
An electrode base holding an internal electrode, an intermediate electrode, and an external electrode, a circuit board on which a circuit section is mounted and disposed on the opposite side of the external electrode across the electrode base, and the circuit board is formed into a cylinder shape with a bottom. The outer electrode is formed into a cylindrical shape with a bottom, and the opening edge of one of the shield case and the outer electrode is formed on the peripheral wall of the other. A clip piece with a convex portion that engages with the concave and convex portions from the inside is protruded into the clip hole, and the external electrode and the shield case are connected in a state where the shield case and the external electrode are connected with their opening surfaces facing each other. The external electrode and the shield case are electrically and mechanically connected via a clip piece, so the external electrode can also serve as a shield. Unlike the conventional method, there is no need to further provide a shield case outside the external electrode, and the number of parts and storage space can be reduced, resulting in advantages such as cost reduction and miniaturization. In addition, the shield case and the external electrode are both formed in a cylindrical shape with a bottom and are coupled with their opening surfaces facing each other, and at the coupling site, a clip hole provided in one peripheral wall has a clip protruding from the edge of the other opening. Since the protrusions of the clip piece are engaged from the inside, the shield case and the external electrode can be easily attached and detached.Moreover, the shield case and the external electrode can be easily connected without applying external force to the protrusion of the clip piece. Since it does not fall off, it has the advantage that the radiation source will not be dissipated even if it falls off during a fire or the like.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view showing an embodiment of the present invention;
FIG. 2 is an exploded perspective view showing the usage pattern of the same as above. 21... Radiation source, 22... Internal electrode, 23...
...External electrode, 23b...Introduction hole, 23c...Clip piece, 24...Intermediate electrode, 25...Electrode base,
26...Printed circuit board, 27...shield case, 27b...clip hole.

Claims (1)

[Scope of claim for utility model registration] (1) An internal electrode that holds a radiation source, an external electrode that is arranged to surround the outside of the internal electrode and has an introduction hole that introduces smoke into the internal electrode, and an internal electrode. and an intermediate electrode having at least one through hole disposed between the external electrode and the radiation source through which radiation from the radiation source can pass, and when smoke comes into contact with the ionized gas in the external electrode. A sensor unit of an ionization type smoke detector that detects smoke by detecting changes in ion current includes an electrode base that holds an internal electrode, an intermediate electrode, and an external electrode, and an electrode base on which a circuit is mounted. The circuit board is disposed on the opposite side of the external electrode, and the shield case is shaped like a cylinder with a bottom and houses the circuit board between the electrode board and the external electrode. The bottom is formed into a cylindrical shape, and a clip piece with a convex portion protruding from the opening edge of one side of the shield case and the external electrode is provided to engage the clip hole formed in the other peripheral wall from the inside. An ionization type smoke detector comprising an external electrode and a shield case that are mechanically and electrically connected via a clip piece in a state in which the external electrode and the external electrode are connected with their opening surfaces facing each other. (2) The ionization type smoke sensor according to claim 1, wherein the introduction hole of the external electrode is formed smaller than that of the internal electrode.