Overheat protection device and electrical system having same
First Claim
1. An overheat protection device comprising a variable resistive element for which resistance varies depending on temperature and which is a polymer PTC element, characterized in that the device further comprises a switching element which controls a current flowing through an electrical system depending on an applied voltage thereto, and a resistor having a resistance R, said electrical system comprising a secondary battery, and the variable resistive element is composed of a plurality of variable resistive elements at least some of which are electrically connected in series with each other, the variable resistive element being located on and thermally combined with a certain position of the electrical system and interrupts the current flowing through the electrical system by changing the applied voltage to the switching element when the certain position comes to be under a high temperature condition, the variable resistive element having a resistance in a high temperature state PH and a resistance in a low temperature state PL, the relationship between the resistance of the variable resistive element and the resistor being R/PL>
- 10 and R/PH<
1/10.
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Accused Products
Abstract
The present invention provides an overheat protection device which is capable of effectively preventing a secondary battery from overheating. In the overheat protection device (20), a variable resistive element(s) (11) of which resistance varies depending on a temperature is located on and thermally combined with a certain position(s) of an electrical system (1), and a switching element (15) for controlling a current depending on an applied voltage thereto is arranged so as to control the current flowing through the electrical system (1). When the certain position of the electrical system (1) comes to be under a high temperature condition, the variable resistive element (11) interrupts the current flowing through the electrical system (1) by changing the applied voltage to the switching element (15).
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Citations
8 Claims
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1. An overheat protection device comprising a variable resistive element for which resistance varies depending on temperature and which is a polymer PTC element, characterized in that the device further comprises a switching element which controls a current flowing through an electrical system depending on an applied voltage thereto, and a resistor having a resistance R, said electrical system comprising a secondary battery, and the variable resistive element is composed of a plurality of variable resistive elements at least some of which are electrically connected in series with each other, the variable resistive element being located on and thermally combined with a certain position of the electrical system and interrupts the current flowing through the electrical system by changing the applied voltage to the switching element when the certain position comes to be under a high temperature condition, the variable resistive element having a resistance in a high temperature state PH and a resistance in a low temperature state PL, the relationship between the resistance of the variable resistive element and the resistor being R/PL>
- 10 and R/PH<
1/10. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
- 10 and R/PH<
Specification