JP4194928B2 - High sensitivity fuse - Google Patents

Description

  The present invention relates to a high-sensitivity fuse used for protection of an electric system such as a vehicle.

  In recent years, occupant protection devices using supplemental restraint systems such as airbags and seat belt pretensioners are becoming popular in order to protect occupants in vehicles and the like. In such an occupant protection device, an auxiliary restraint device is disposed at a necessary place, and when an impact is applied to the vehicle, the sensor detects this and the auxiliary restraint device prevents the occupant from colliding with an object in the passenger compartment. Temporarily restrain and protect.

  Conventionally, since the number of auxiliary restraint devices arranged in the vehicle is small, the connection between the control device that controls the auxiliary restraint device and the ignition device that operates the auxiliary restraint device is, for example, a simple one-to-one connection ( Recently, the number of auxiliary restraint devices tends to increase because the auxiliary restraint devices are arranged at various locations in the vehicle. Between the control device and the control device and the ignition device of the auxiliary restraint device, It is required to reduce the number of connecting wires (harness) to be connected as much as possible. Therefore, the connection between the control device and the ignition device of the auxiliary restraint device is connected by a bus line capable of transmitting electric power and a control signal, and a plurality of auxiliary restraint devices connected to the bus line are subjected to ignition control by communication. A method of using one control device for control has been proposed (see, for example, Patent Document 1).

Further, in the conventional method of connecting the control device and the ignition device of the auxiliary restraint device by a bus line, a plurality of auxiliary restraint devices can be efficiently controlled by one control device, but a plurality of auxiliary restraint devices can be controlled. Since the connection line for transmitting power or control signals to the apparatus is only a bus line, there is a problem that the transmission of power or control signals through the bus line must be highly reliable. In particular, when the ignition device includes a communication circuit between the control device and an ignition circuit that operates the auxiliary restraint device as in the conventional ignition device, the ignition provided in the activated auxiliary restraint device. It is necessary to give sufficient consideration so that the device does not electrically affect the bus line, and to further improve the reliability of the bus line.
Therefore, in order to disconnect the ignition device provided in the activated auxiliary restraint device from the bus line, it is detected by detecting a current that needs to be melted in the connection line between the bus line and the ignition device of the auxiliary restraint device. For example, a method of inserting a fuse as described in Patent Document 2 is conceivable.
Japanese Patent Laid-Open No. 10-154992 JP-A-8-64106

  By the way, in the conventional method, the communication by the bus line between the control device and the ignition device of the auxiliary restraint device is performed at a speed of the microsec order. On the other hand, conventional fuses have the property that if the difference between the rated current of the fuse and the current that needs to be blown is small, it takes time until the fuse element blows. Therefore, for the purpose of separating the ignition device provided in the actuated auxiliary restraint device from the bus line, the connection line between the bus line and the ignition device of the auxiliary restraint device is described in, for example, Patent Document 2 Even if a conventional fuse is inserted, there is a problem that the effect of improving the reliability of the bus line may not be obtained sufficiently, and when a current that requires fusing flows, the connection between both terminals is short A fuse that can be cut in is needed.

  The present invention has been made in view of the above problems, and includes a fuse element that blows in a short time when a current that requires fusing flows even when the difference between the rated current of the fuse and the current that requires fusing is small. The purpose is to provide a highly sensitive fuse.

In order to solve the above-mentioned problem, a high-sensitivity fuse according to the invention of claim 1 is a fuse element at a temperature near the melting point of titanium constituting a fuse element (for example, a fuse element 3 or a fuse element 6 in an embodiment described later). Boron that causes a chemical reaction with titanium and explodes (for example, a reactive substance 4 and a reactive substance 7 in Examples described later) is disposed adjacent to the fuse element.

  In the high-sensitivity fuse having the above configuration, when the material constituting the fuse element is about to be blown by an electric current that needs to be blown, the reactant disposed adjacent to the fuse element causes the material of the fuse element to be A chemical reaction is rapidly caused with the material at a temperature close to the melting point, and the fuse element is blown off by explosion. Therefore, the fusing time of the fuse element can be further shortened.

Furthermore , when the titanium constituting the fuse element is about to melt, the boron disposed adjacent to the titanium causes a rapid chemical reaction with the titanium at a temperature near the melting point of the titanium and explodes and blows off the titanium. The fusing time of fuse elements made of titanium can be shortened

  According to the high sensitivity fuse of the first aspect, the fusing time of the fuse element can be further shortened. Therefore, the effect that the connection between both terminals of the fuse can be cut in a short time when a current that requires fusing flows. In particular, for example, in an occupant protection device that connects the connection between the conventional control device and the ignition device of the auxiliary restraint device by a bus line, for the purpose of separating the ignition device provided in the operated auxiliary restraint device from the bus line, When this high-sensitivity fuse is inserted into the connection line between the bus line and the ignition device of the auxiliary restraint device, the ignition device provided in the activated auxiliary restraint device is assisted so as not to electrically affect the bus line. An effect is obtained that the ignition device in which a current that requires fusing flows when the restraint device is operated can be disconnected in a short time, and the reliability of the bus line can be further improved.

In particular, by using titanium for the fuse element and boron for the reactant, the fusing time of the fuse element made of titanium can be shortened more reliably, and the reliability of the bus line can be further improved. The effect that it can be obtained.

  Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a configuration of a high-sensitivity fuse according to an embodiment of the present invention.
In FIG. 1, for example, a high-sensitivity fuse has two conductive caps 2 a and 2 b bonded to both ends of a glass tube 1, and a fuse element 3 is disposed in the glass tube 1. Further, a reactive substance 4 that causes an abrupt chemical reaction with the material and explodes at a temperature near the melting point of the material constituting the fuse element 3 and blows off the material (fuse element 3) is attached to the fuse element 3. Then, both ends of the fuse element 3 and the reactive substance 4 are fixed to the two conductive caps 2a and 2b together with the lead wires 5a and 5b by soldering, and the fuse element 3 and the reactive substance 4 are enclosed in the glass tube 1. .

  As a result, when the current flowing through the high-sensitivity fuse becomes a current that needs to be blown above the rated current of the high-sensitivity fuse, the temperature of the fuse element 3 rises due to Joule heat. When the temperature of the fuse element 3 reaches the melting point temperature of the fuse element 3, the fuse element 3 is melted and the reactant 4 explodes due to a rapid chemical reaction with the material constituting the fuse element 3, The fuse element 3 is blown off in the A direction, for example.

  FIG. 2 shows the configuration of the high-sensitivity fuse when the high-sensitivity fuse is realized by a chip component for surface mounting. As shown in FIG. 2, when a high-sensitivity fuse is constituted by a chip component for surface mounting, a fuse element 6 and a reactive substance 7 attached to the fuse element 6 are formed on the ceramic substrate 9 by vapor deposition or sputtering. At the same time, the fuse element 6 is sandwiched between two solder-plated electrodes 8a and 8b, and the fuse element 6 and the electrodes 8a and 8b are connected to form a current path by the fuse element 6 between the electrodes 8a and 8b. To do.

  Therefore, similarly, when the current flowing through the high-sensitivity fuse becomes a current that needs to be blown above the rated current of the high-sensitivity fuse, the temperature of the fuse element 6 rises due to Joule heat. When the temperature of the fuse element 6 reaches the melting point temperature of the fuse element 6, the fuse element 6 is melted and the reactant 7 explodes due to a rapid chemical reaction with the material constituting the fuse element 6, The fuse element 6 is blown off in the A direction, for example.

  In the above-described embodiment, the material constituting the fuse element 3 or the fuse element 6 and the reactant 4 that explodes by causing a rapid chemical reaction with the material at a temperature near the melting point of the material and blows off the material. Examples of the combination of the reactants 7 include a combination of titanium and boron (boron). Specifically, when boron is attached as the reactive substance 4 or the reactive substance 7 to the fuse element 3 or the fuse element 6 made of titanium, the fuse element 3 or the fuse element 6 is caused by Joule heat when a current that requires fusing flows. When the temperature of the fuse element 3 and the fuse element 6 exceeds, for example, 1668 [° C.] which is the melting point temperature of titanium, the fuse element 3 and the fuse element 6 are melted, and the reactant 4 and the reaction Boron, which is the substance 7, and titanium constituting the fuse element 3 and the fuse element 6 cause an abrupt chemical reaction to explode and blow off the fuse element 3 and the fuse element 6, so that the fuse element is blown out in a shorter time.

As described above, according to the high-sensitivity fuse of the present embodiment, the material constituting the fuse element 3 or the fuse element 6 is attached to the fuse element 3 or the fuse element 6 when attempting to blow by the current that needs to be blown. Since the reactive substance 4 and the reactive substance 7 are suddenly chemically reacted with the material at a temperature near the melting point of the material constituting the fuse element 3 or the fuse element 6 and explode to blow off the fuse element 3 or the fuse element 6. The fusing time of the fuse element 3 and the fuse element 6 can be further shortened. Specifically, for example, the time required for a normal fuse to blow is about 100 milliseconds, whereas the time required for the high-sensitivity fuse of this embodiment to blow can be about 10 to 50 microseconds. .
Therefore, when a current that requires fusing flows, the connection between the two conductive caps 2a, 2b of the fuse or between the electrodes 8a, 8b can be cut in a short time.

  In particular, for example, in an occupant protection device that connects a connection between a conventional control device and an ignition device of an auxiliary restraint device by a bus line, for the purpose of separating the ignition device provided in the activated auxiliary restraint device from the bus line, If this high-sensitivity fuse is inserted into the connection line between the bus line and the ignition device of the auxiliary restraint device, the ignition device provided in the activated auxiliary restraint device will be assisted so as not to electrically affect the bus line. An effect is obtained that the ignition device can be disconnected in a short time when the restraint device is operated, and the reliability of the bus line can be further improved.

It is a figure which shows the structure of the high sensitivity fuse of one Example of this invention. It is a figure which shows the structure in the case of implement | achieving the high sensitivity fuse of the Example with the chip components for surface mounting.

Explanation of symbols

3, 6 Fuse element 4, 7 Reactant

Claims (1)

A high-sensitivity fuse, wherein boron that explodes due to a chemical reaction with titanium of the fuse element at a temperature near the melting point of titanium constituting the fuse element is disposed adjacent to the fuse element.

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