Yazaki Corporation

Osamu Soda

Satoshi Ishikawa

Hisafumi Maruo

A safety device of an electric circuit is provided, in which a thermal fuse securely prevents an accident from occurring when an overcurrent protector is extraordinarily overheated. The safety device includes: first protective means in an overcurrent protector for protecting the electric circuit from an overcurrent, which generates heat to increase its electrical resistance when an overcurrent flows in the electric circuit, whereby reducing or cutting off the overcurrent; and second protective means including a thermal fuse situated in the vicinity of the overcurrent protector containing: a first electrode having a first conductor pattern connected to the overcurrent protector; a second electrode having a second conductor pattern insulated from the first electrode by a gap; and solder connecting the first and second electrodes and melting by heat from the overcurrent protector so as to split into two parts toward the first and second electrodes. According to the safety device, the thermal fuse can quickly operate when the overcurrent protector is extraordinarily overheated and be easily formed by employing an automatic soldering machine and the like.

Safety device of electric circuit and process for producing the same

A safety device for preventing a trouble caused by an abnormal overheating of an electric circuit is provided, which includes: a circuit board; a first circuit pattern; a second circuit pattern; a first electrode connected to the first circuit pattern; a second electrode connected to the second circuit pattern, while enclosing the first electrode without a break, the second electrode being standoff-insulated from the first electrode; and a solder fuse portion made of a solder and formed over and inside the second electrode for bridging the first and second electrodes, wherein the solder fuse portion in a melted state separates onto the first and second electrodes by surface tension of the solder, whereby a circuit between the first and second circuit patterns is broken. Thus, a safety device for an electric circuit, which can be easily formed with the same and normal solder as used for connecting electrical parts, while having high reliability as a fuse and simultaneously being capable of reducing manufacturing cost, can be realized.

Safety device for electric circuit

A circuit protective device with a positive temperature coefficient element is provided, which includes: a positive temperature coefficient (hereinafter 'PTC') element, made of a conductive composition having a PTC characteristics, provided for shutting off an electric circuit; a circuit board having the PTC element and electrodes to be connected with the PTC element; and a slot formed on the circuit board so as to prevent a low resistance conductive passage from being formed between the electrodes, the low resistance conductive passage being made of powder of the conductive composition released from the PTC element. And also an electric junction box with the above circuit protective device is provided. Thus, the circuit protective device or the electric junction box with the circuit protective device wherein a low resistance conductive passage made of a carbonaceous powder to be released from the PTC element is not formed between the electrodes of the PTC element can be realized.

Circuit protective device with positive temperature coefficient element

The connection structure of a circuit protection element for securely connecting at least two lead terminals of the circuit protection element to a circuit board includes terminal connection elongated holes each provided in the circuit board for connecting the lead terminals to the circuit board by soldering. The circuit board is positioned in such a way that the elongated direction of the elongated terminal connection hole is positioned in a downward direction. When an abnormal current is applied to the circuit, or when the circuit protection element fails to heat itself up to a high temperature, the solder melts. Thereby, the lead terminals easily disengage from the terminal connection holes so that the circuit protection element falls freely from the circuit board. Thus, the circuit is surely cut off easily.

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Shizuoka, Japan

Osamu Soda