JPS5829880Y2 - Automotive cylinder fuse - Google Patents

Description

[Detailed description of the invention] This invention relates to the improvement of cylinder fuses for automobiles.
The purpose is to provide a cylinder fuse for automobiles that can ensure melting under overcurrent, has a long life even under currents below the rated value, and is easy to confirm when the fusible material breaks.

Generally, automotive fuses are required to have the following performance.

(a) Overcurrent exceeding the rated current must be fused within a specified time.

(b) When repeatedly using ON-OFF at a current lower than the rated current, it must not melt down more than the specified number of times.

(c) Conditions (a) and (b) above must also be met with respect to shocks and vibrations during driving.

By the way, as shown in FIG. 1, a commonly used automotive tube fuse has conductive caps 2, 2 fixed to both ends of a transparent glass tube 1, respectively. Both ends of the strip-shaped fusible body 3 are soldered 4
It is used by fixing and holding the bases 2, 2 into clip-type terminals (not shown) and connecting them to a circuit to be protected.

The fusible body 3 is generally made of pure zinc material, has a narrow constriction 3a in its center, and has a shape and dimensions determined to provide prescribed fusing characteristics against overcurrent.

The glass tube 1 protects the fusible body 3 together with the caps 2 and 2 from water, dust, etc., and allows the inside to be seen through to check the state of melting of the fusible body.

Conventional cylinder fuses for automobiles like this have a rating of 70%.
Load current, 10 seconds ON, 10 seconds OFF condition (JA
30,000 to 50,000 to 50,000
It will melt after about 10,000 cycles, and depending on the load, the lifespan may be very short.

Therefore, like the stop lamp load of a car (load current is about 7A for 23W 4 lamps), etc.
If used in applications where there is a high frequency of

This is thought to be due to the following reasons.

That is, as shown in FIG.
, 2. If the material is fixed and held by soldering, stress accumulates inside the fusible material due to repeated thermal expansion when the current is applied and contraction when the current is interrupted, and this causes material fatigue, which accelerates the breakage of the fusible material. It turns out.

The present invention was devised in view of these facts, and includes a tube fuse for automobiles in which a strip-shaped fusible material is held between a base fixed to a glass tube, in which at least one end of the fusible material is By holding the fusible material in a slidable manner so as not to hinder its expansion and contraction due to temperature changes, a clamping member made of an elastic conductive material provided in close contact with the cap prevents the cause of premature fuse blowout as described above. In addition to improving durability when the fusible material is removed, when the fusible body breaks, the gap at the breakage portion is enlarged so that the breakage can be easily confirmed.

Hereinafter, the structure of the present invention will be specifically explained with reference to FIG. 2 and subsequent figures of the accompanying drawings.

FIG. 2 is a sectional view of both ends of a tube fuse showing an embodiment of the present invention, in which figure a shows a cross section perpendicular to the fusible body 3 along the center line of the tube fuse, and b shows the same cross section. A cross section parallel to the fusible body 3 is shown.

FIG. 3 is a perspective view of the holding member 5 shown in FIG. 2.

In this embodiment, the clamping member 5 is made of an elastic conductive material such as a phosphor plate, and has a fixed portion 6 in the center and a pair of tongue pieces 7, 7.
have.

Arc-shaped peripheral portions 8, 8 on both sides of the fixing portion 6 in the X-axis direction in FIG. 3 are held between the glass tube 1 and the cap 2, as shown in FIGS.

In this way, the holding member 5 can be fixed such that the back surface of the fixing portion 6 is in close contact with the base 2 without requiring riveting or soldering.

The tongue piece 7.7 has a developed shape and extends in a rectangular shape on both sides of the fixing part 6 in the X-axis direction in FIG. I was told,
The clamping member 5 as a whole is integrally formed in a C-shape.

Both ends of the strip-shaped fusible body 3 are slidably held between the tongues 7, 7, and electricity is applied to the fusible body 3 from the base 2 through the contact surfaces.

The contact pressure of the tongues 7, 7 with respect to the fusible body 3 is set so as to ensure electrical conduction of the contact surface and not to prevent the fusible body 3 from expanding and contracting due to temperature changes.

In addition, the relationship between the distance between the caps 2, 2 and the length of the fusible body 3 is as follows:
The setting is such that when the fusible body 3 thermally expands, both ends thereof do not come into contact with the fixed portion 6 of the holding member 5 at the same time.

Therefore, even if one end of the fusible body 3 hits the fixed portion 6 of the clamping member 5 during assembly, this does not hinder the achievement of the object of the present invention.

Next, considering the influence of thermal expansion of the holding member 5, even if the fixed part 6 expands due to heating during energization, the extension of the fixed part 6 in the Y-axis direction and the extension of the tongues 7, 7 in FIG. Since the component in the Y-axis direction generally takes approximately the same value, the tongue pieces 7, 7
There is almost no change in the contact pressure against the fusible body 3.

That is, the influence of thermal expansion can be ignored.

Furthermore, with respect to the elongation of the fixed part 6 in the X-axis direction, if a sufficient dimensional margin is provided between the peripheral part 8 and the cap 2,
there is no problem.

The holding member 5 can also be fixed to the base 2 by riveting, soldering, or the like.

The clamping member 5 shown in FIG.
and a U-shaped notch 11 extending from the tip of the tongue piece 7 to the vicinity of the fixing part 6, so that a riveting tool can be inserted into this notch 11.

In this case, the fixed portion 6 may be rectangular.

Further, although FIG. 2 shows a case where both ends of the fusible body 3 are held between the holding members 5, only one end of the fusible body 3 is slidably held between the holding members 5, and the other end is held between the holding members 5. The object of the present invention can be distantly related even if it is fixedly held on the base 2 by soldering.

As explained above, in the present invention, at least one end of the fusible body is slidably clamped by the clamping member, so that when the fusible body contracts due to thermal expansion and heat radiation, the fusible body and the clamping member The expansion and contraction of the fusible material will not be hindered due to misalignment of the contact surface.

Therefore, the accumulation of mechanical stress on the fusible body is avoided, and the lifespan can be expected to be improved against repeated intermittent energization, and the contact pressure between the fusible body and the clamping member remains almost constant even during their thermal expansion. Therefore, it is possible to ensure the specified fusing performance as an automobile cylinder fuse.

Further, according to the present invention, when the fusible body thermally ruptures, it breaks in a thermally expanded state, that is, in a state where the contact position with respect to the clamping member is shifted by the elongation of the fusible body, and then the fusible body breaks due to heat dissipation. The shrinkage occurs while the divided fusible bodies are being held by the clamping members at the contact positions at the time of breakage, so the gap at the breakage portion is enlarged, which also has the effect of making it easier to confirm the breakage.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a conventionally used cylinder fuse for an automobile, Fig. 2 a, l) is a sectional view of both end portions of a cylinder fuse for an automobile showing an embodiment of the present invention, and Fig. 3 is a perspective view of a cylinder fuse for an automobile conventionally used. , a perspective view of the holding member shown in FIG. 2, and FIG. 4 is a partial perspective view showing another example of the holding member. Explanation of symbols 1. Glass tube, 2: Cap, 3: Fusible material, 5
: Holding member, 6: Fixed part, 7: Tongue piece, 8: Peripheral part, 1
0: Chain type, 11: U-shaped notch.

Claims (5)

[Scope of utility model registration request] (1) In an automobile tube fuse in which a strip-shaped fusible material is held between caps fixed to both ends of a glass tube, at least one end of the fusible material is provided with an elastic material in close contact with the cap. A cylindrical fuse for an automobile, characterized in that it is slidably held by a holding member made of a conductive material so as not to prevent the expansion and contraction of the fusible material due to temperature changes. (2) The holding member is formed into a C-shape consisting of a fixed part in the center and a pair of tongues extending from the fixed part on both sides and bent so that their tips are close to each other and face each other. A cylinder fuse for an automobile according to claim 1 of the utility model registration claim, characterized in that: (3) A tube fuse for an automobile according to claim 2, wherein a peripheral portion of the fixed portion of the holding member is held between the glass tube and the cap. (4) The tube fuse for an automobile according to claim 2, wherein the fixed portion of the holding member is riveted to the cap. (5) The cylinder fuse for an automobile according to claim 4, wherein the holding member is provided with a U-shaped notch extending from the tip of the tongue piece to the vicinity of the fixing part.