# US 10,483,061 B2 · Protective device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,483,061 B2 - Document ID: US10483061B2 - Status: Granted - Kind: B2 - Application number: 14/901,987 - Filed: 2014-07-01 - Published: 2018-02-08 - Granted: 2019-11-19 - Earliest claimed: 2013-07-02 - Assignees: Littelfuse Japan G.K. - Applicants: Littelfuse Japan G.K. - Inventors: Takayuki Yokota; Masaaki Iwai; Hirotsugu Takegawa; Naotaka Ikawa - Web page: https://patentgrep.com/patent/US10483061B2 ## CPC - H01H 37/34: Means for transmitting heat thereto, e.g. capsule remote from contact member - H01H 37/60: Means for producing snap action (inherent in bimetallic element H01H37/54; caused by a magnet H01H37/66) - H01H 85/46: Circuit arrangements not adapted to a particular application of the protective device - H02H 3/085: {making use of a thermal sensor, e.g. thermistor, heated by the excess current (also responsive to the temperature of the protected device H02H5/041, thermal images H02H6/00)} - H01C 7/02: having positive temperature coefficient - H01H 37/761: {with a fusible element forming part of the switched circuit (H01H37/767 takes precedence)} - H01H 61/02: wherein the thermally-sensitive member is heated indirectly, e.g. resistively, inductively - H01H 85/0241: {Structural association of a fuse and another component or apparatus (switches with built-in fuses H01H9/10, spark-gap arresters H01H85/44, transformers and inductances H01F27/402, capacitors H01G2/14, lamps H01K1/66, semiconductors H10W20/493 or H10W42/80)} - H01H 2235/01: Spiral spring - H01H: ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES (contact cables H01B7/10; electrolytic self-interrupters H01G9/18; emergency protective circuit arrangements H02H; switching by electronic means without contact-making H03K17/00) - H02H: EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS (indicating or signalling undesired working conditions G01R, e.g. G01R31/00, G08B; locating faults along lines G01R31/08; emergency protective devices H01H) - H01C: RESISTORS ## Abstract A protection device including: (i) a protection component having a first thermal fuse and a resistive body, the resistive body being supplied with a current in an abnormal state to generate heat, the heat activating the first thermal fuse to cut off the current; (ii) a PTC component; and (iii) a second thermal fuse, the second thermal fuse being electrically connected in series to the PTC component, the first thermal fuse of the protection component being electrically connected in parallel to the PTC component and to the second thermal fuse, and the protection component being activated in the abnormal state so that the PTC component trips to generate heat, the heat blowing the second thermal fuse. ## Claims ### Claim 1 A protection device comprising: (i) a protection component comprising a first thermal fuse and a resistive body wherein in an abnormal state the resistive body is supplied with a current to generate heat, and by the heat the first thermal fuse activates to cut off the current; (ii) a PTC component; and (iii) a second thermal fuse, wherein the second thermal fuse is electrically connected to the PTC component in series, the first thermal fuse of the protection component is electrically connected to the PTC component and to the second thermal fuse in parallel, and by activating the protection component in the abnormal state, the PTC component trips to generate heat, and the heat fuses the second thermal fuse; wherein an activating time of the PTC component is longer than an insulation time of a fuse element of the first thermal fuse. ### Claim 2 (depends on 1) The protection device according to claim 1, wherein the protection component is a fusing resistor. ### Claim 3 (depends on 2) The protection device according to claim 2, wherein the fusing resistor has a pair of lead fixed electrodes, a guide shaft is juxtaposed to the lead fixed electrodes, wherein a movable electrode is disposed such that it bridges the lead fixed electrodes while being inserted into the guide shaft, a tip of each of the lead fixed electrodes and the movable electrode are joined with a low-melting-point alloy, and the guide shaft and the movable electrode is joined with a low-melting-point alloy, a compression spring is provided which applies a force to the movable electrode in a direction away from the lead fixed electrodes, and when the low-melting-point alloy is melted, the compression spring presses the movable electrode so that the movable electrode separates from the lead fixed electrodes. ### Claim 4 (depends on 3) The protection device according to claim 3, wherein in the fusing resistor, one lead conductor of a resistor having lead conductors fitted to both ends of the resistive body is used as the guide shaft, a coil spring is used as the compression spring, the coil spring is inserted in the one lead conductor between the resistive body and the movable electrode, and a circuit applying a current to a resistor for generating a heat is connected between the one lead conductor of the resistor and either one of the two lead fixed electrodes. ### Claim 5 (depends on 1) The protection device according to claim 1, wherein the PTC component is a polymer PTC component. ### Claim 6 (depends on 1) The protection device according to claim 1, wherein a resistance value of the PTC component at a use temperature is equal to or less than a rated voltage of the protection component/abnormal current. ### Claim 7 (depends on 5) The protection device according to claim 5, wherein a resistance value of the PTC component at a temperature lower 10° C. than a softening point of a polymer material of the polymer PTC component is equal to or less than a rated voltage of the protection component/abnormal current. ### Claim 8 (depends on 1) The protection device according to claim 1, wherein an activating time of the PTC component is 3 milliseconds or more. ### Claim 9 (depends on 1) The protection device according to claim 1, further comprising one or more PTC components electrically connected to the PTC component in parallel and electrically connected to the second thermal fuse in series. ### Claim 10 (depends on 1) The protection device according to claim 1, wherein an activation temperature of the second thermal fuse is lower than a trip temperature of the PTC component. ### Claim 11 (depends on 1) The protection device according to claim 1, wherein a fusing time of the second thermal fuse at an abnormal current is longer than a tripping time of the PTC component. ### Claim 12 (depends on 1) The protection device according to claim 1, wherein the second thermal fuse has a withstand voltage equal to or more than an abnormal voltage at a leak current when the PTC component is in its tripping state.