CN2144852Y

CN2144852Y - Overcurrent protection quick response forward temp. coefficient thermal resistor

Info

Publication number: CN2144852Y
Application number: CN 92238602
Authority: CN
Inventors: 蔡雅凤
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-10-29
Filing date: 1992-10-29
Publication date: 1993-10-27
Anticipated expiration: 2002-10-29

Abstract

The utility model relates to a thermistor which has overcurrent protection and fast responds positive temperature coefficient. Electrode lead-out sheets (2) and (3) and a ceramic PTC thermistor sheet (4) are all arranged in a ceramic or metallic outer shell (1), and the tight and elastic pressure connection is formed. As the electrode lead-out sheets and the outer shell increase the heat radiation area, the ceramic PTC thermistor sheet with small size has thermal equilibrium. The utility model achieves the purposes of no thermal breakdown and fast response, and overcomes the defects of easy thermal breakdown, leading wires drop and long response time in the existing ceramic PTC thermistor which is packaged by soldering leading wires and plastic. The utility model can be used for SPC telephone exchangers and other electronic devices with weak overcurrent resistance ability.

Description

Overcurrent protection quick response forward temp. coefficient thermal resistor

The utility model relates to a kind of overcurrent protection and responds positive temperature coefficient (PTC) thermistor fast, is used for the overcurrent protection of SPC telephone exchange and other electronic equipments.

Existing overcurrent protection PTC themistor is when requiring to weld; all adopt soldering lead-in wire on ceramic PTC thermosensitive resistor film; in order to reach heat balance; avoid thermal breakdown; require to strengthen the size of ceramic PTC thermosensitive resistor film, ceramic PTC thermistor chip size is big, and then thermal capacity is big; response time is long, does not play protective effect.Come off for fear of overheated soldering lead-in wire, often adopt the soldering lead-in wire to add powdered plastic and seal, its result causes ceramic PTC themistor to be difficult for heat radiation, and running current (130mA was failure to actuate in 1 hour) be can't pass.

The utility model has solved an above-mentioned difficult problem, we adopt undersized ceramic PTC thermosensitive resistor film (4), pack in the good pottery or metal shell (1) of heat conduction, heat radiation with electrode lead-out tablet (2) and (3), adopt this structure to satisfy the requirement of the weak electronic equipment of SPC telephone exchange and other anti-overcurrent capability fully.Its principle is: ceramic PTC thermistor chip size is little, and thermal capacity is little, so response speed is fast, switches on moment in abnormal electrical, and ceramic PTC thermosensitive resistor film at first generates heat to switch temperature (T ₂) more than, become high-impedance state (off-state), again heat is passed to ceramic package or metal shell and exhale.Therefore, owing to increase electrode lead-out tablet and ceramic package or metal shell, only can increase the area of dissipation of ceramic PTC thermosensitive resistor film, make running current (130mA, be failure to actuate in 1 hour) be able to by, and don't can influence response time of ceramic PTC thermosensitive resistor film, reach quick response purpose.

Below in conjunction with drawings and Examples the utility model is further specified:

Fig. 1 is the cutaway view of the structure of first embodiment of the utility model;

Fig. 2 is the cutaway view of the structure of second embodiment of the utility model;

Fig. 3 is the outline drawing of the structure of the 3rd embodiment of the utility model;

Fig. 3-A is the A-A profile of Fig. 3;

Fig. 3-B is the B-B profile of Fig. 3;

Among the figure: 1. shell, 2.3. electrode lead-out tablet, 4. pottery (PTC) thermosensitive resistor film, 5. conduction insulating cement, 6.7. insulating trip.

Embodiment of the present utility model:

In first embodiment shown in Figure 1, shell is a ceramic package, a side of electrode lead-out tablet (3) closely is connected with an electrode of ceramic PTC thermosensitive resistor film (4), another side of electrode lead-out tablet (3) contacts closely with the inwall of ceramic package (1), and electrode lead-out tablet (2) is connected with the another side electrode elastic pressure of ceramic PTC thermosensitive resistor film (4).

In second embodiment shown in Figure 2, shell is a metal shell, a side of electrode lead-out tablet (3) closely is connected with an electrode of ceramic PTC thermosensitive resistor film (4), another side of electrode lead-out tablet (3) contacts closely with the metal shell inwall, electrode lead-out tablet (2) is connected with the another side electrode elastic pressure of ceramic PTC thermosensitive resistor film, insulating trip (6) is contained between electrode lead-out tablet (2) and the metal shell (1), and insulating trip (7) makes the periphery and metal shell (1) insulation of ceramic PTC thermosensitive resistor film (4).

In the 3rd embodiment shown in Figure 3, two unit are arranged, a side of the electrode lead-out tablet (3) of each unit closely is connected with an electrode of ceramic PTC thermosensitive resistor film (4), another side of electrode lead-out tablet (3) contacts closely with the inwall of ceramic package (1), and electrode lead-out tablet (2) is connected with the another side electrode elastic pressure of ceramic PTC thermosensitive resistor film (4).

Employed insulating trip can be with ceramic sheet or mica manufacturing among the embodiment.Thermosensitive resistor film can be circular, also can be quadrangle.

Adopt switch temperature

Be 80 ± 5 ℃, volume resistivity ρ v=30 Ω .cm, lift-drag ratio is greater than 10 ⁵, compressive resistance u 〉=150V _～The ceramic ptc material of/mm; pottery PTC thermosensitive resistor film is of a size of: disk diameter of phi=7～8mm; thickness t=1.5～2.0mm; rectangle length of a film L=8～9mm, wide b=5～6mm, thick t=1.5～2.0mm; according to the utility model Fig. 1; Fig. 2 and structure shown in Figure 3 are made the overcurrent protection that is used for the SPC telephone exchange Security Unit and are responded ceramic PTC themistor fast, reach following performance index: room temperature resistance R ₂₅=15～22 Ω; Switch temperature T ₂=80 ± 5 ℃; Withstand voltage u=220V _～, do not puncture in 15 minutes; Impact the life-span: impulse current 2A, 100 times, △ R/R ₂₅≤ ± 10%, fictitious load RJ-2W-50 Ω metal film resistor does not burn; Running current: 130mA was failure to actuate in 1 hour; Response time: 2A, t≤0.40s; 1A, t≤1s; 0.75A, t≤5s; 0.5A, t≤10s.

Advantage of the present utility model, with present welding with seal the ceramic PTC thermal resistor and compare tool

Have response speed to bring disaster to, protect effectively, can be overheated do not fall lead-in wire, be difficult for thermal breakdown, its response speed contrasts as follows:

	2A.t≤	1A,t≤	0.75A,t≤	0.5A,t≤
					The utility model embodiment	0.4s	1.0s	5s	10s
Weld packaged products at present	0.5s	1.5s	10s	20s

Claims

1; a kind of overcurrent protection responds positive temperature coefficient thermistor fast; comprise pottery (PTC) thermosensitive resistor film (4); pair of electrodes lead-out tablet (2) and (3); shell (1); thermal conductive insulation glue (5); insulating barrier (6) and (7); its characteristic is: a side of electrode lead-out tablet (3) closely is connected with an electrode of ceramic PTC thermosensitive resistor film (4); another side of electrode lead-out tablet (3) closely contacts with shell (1); electrode lead-out tablet (2) is connected with ceramic PTC thermosensitive resistor film (4) another side electrode elastic pressure; the ceramic PTC thermosensitive resistor film (4) that electrode lead-out tablet (2) and (3) will be housed is packed in the shell (1), makes electrode lead-out tablet (2) form tight the contact with (3) with the double-sided electrode of ceramic PTC thermosensitive resistor film.

2, the overcurrent protection according to claim 1 responds positive temperature coefficient thermistor fast, it is characterized in that: ceramic PTC thermosensitive resistor film (4) is a disk, and it is of a size of diameter phi=7～8mm, thickness t=1.5～2.0mm.

3, the overcurrent protection according to claim 1 responds positive temperature coefficient thermistor fast, it is characterized in that: ceramic PTC thermosensitive resistor film (4) is a rectangle, and it is of a size of long L=8～9mm, wide b=6～7mm, thickness t=1.5～2.0mm.

4, the overcurrent protection according to claim 1 to 3 responds positive temperature coefficient thermistor fast, it is characterized in that: shell is the ceramic package of high heat conduction, heat radiation.

5, the overcurrent protection according to claim 1 to 3 responds positive temperature coefficient thermistor fast, it is characterized in that: shell is the metal shell of high heat conduction, heat radiation.

6, the overcurrent protection according to claim 5 responds positive temperature coefficient thermistor fast; it is characterized in that: between electrode lead-out tablet (2) and metal shell (1), be added with insulating barrier (6), between the periphery of metal shell (1) and ceramic PTC thermosensitive resistor film (4), be added with insulating barrier (7).

7, the overcurrent protection according to claim 6 responds positive temperature coefficient thermistor fast, it is characterized in that: insulating barrier is a ceramic sheet.

8, the overcurrent protection according to claim 6 responds positive temperature coefficient thermistor fast, it is characterized in that: insulating barrier is a mica sheet.