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US 5,645,746 AGranted
Use of PTC devices
AssigneeRaychem Corporation
InventorMalcolm R. Walsh
Life of this patent
Estimating the term…
Abstract
Use of PTC circuit protection devices in motor vehicle wiring systems. The devices can replace some or all of the fuses conventionally used. Preferred devices contain PTC conductive polymers. Because the PTC devices can be reset without physical access to them, the wiring system can be arranged more efficiently and more economically. For example, the size of at least some of the wires of the harness can in many cases be reduced.
Claims52
An electrical system which is installed in a road vehicle, an airplane, or a ship, and which comprises
- (1) a source of electrical power;
- (2) a supply connection means which is electrically connected to a first pole of the power source, and which has, at its weakest current-carrying point, a current-carrying capacity of I.sub.LINK amps,
- (3) a return connection means which is electrically connected to a second pole of the power source;
- and
- (4) a plurality of branch circuits which are electrically connected in parallel between the supply connection means and the return connection means, at least two of the branch circuits being PTC-protected branch circuits, each of said branch circuits comprising
- (a) a branch PTC circuit protection device which
- (i) is electrically connected to the supply connection means directly or via at least one other PTC-protected branch circuit, and
- (ii) is taken from a batch of PTC devices made by the same manufacturing process, the largest steady state current which will not cause any of the devices in the batch to trip being I.sub.PASS and the smallest steady state current which will cause all of the devices in the batch to trip being I.sub.TRIP, I.sub.TRIP being less than I.sub.LINK ;
- (b) an operative electrical device which is spaced apart from the branch PTC circuit protection device;
- and
- (c) an elongate PTC-protected branch connection means which
- (i) electrically connects the branch PTC device and the operative device, and
- (ii) has at all points a current-carrying capacity of at least I.sub.DAMAGE amps, I.sub.DAMAGE being more than I.sub.TRIP ;
- whereby, if the PTC-protected branch connection means is accidentally connected to the first and second poles of the power source by connections which do not include the operative device, there is created a fault circuit which contains the branch PTC circuit protection device and in which the current is initially greater than I.sub.TRIP, thus causing the branch PTC device to trip and reduce the current to a steady state value substantially below I.sub.TRIP ;
- wherein at least one of the following conditions is fulfilled:
- (A) in at least one of the PTC-protected branch circuits,
- (i) at all temperatures between 0.degree. and 80.degree. C. the I.sub.PASS of the branch PTC device in that PTC-protected branch circuit is at least 1.1 times I.sub.LOAD, and
- (ii) at at least one temperature between -40.degree. C. and 85.degree. C., the I.sub.PASS of the branch PTC device in that PTC-protected branch circuit is at most 1.3 times I.sub.LOAD,
- where I.sub.LOAD is the maximum steady state current in that PTC-protected branch circuit under normal operating conditions;
- (B) in at least one of the PTC-protected branch circuits,
- (i) at all temperatures between 0.degree. and 80.degree. C., the I.sub.DAMAGE of the branch connection means in that PTC-protected branch circuit is at least 1.1 times the I.sub.TRIP of the branch PTC device in that PTC-protected branch circuit and
- (ii) at at least one temperature between -40.degree. and 85.degree. C., the I.sub.DAMAGE of the branch connection means in that PTC-protected branch circuit is at most 1.5 times the I.sub.TRIP of the branch PTC device in that PTC-protected branch circuit;
- (C) the total number of PTC-protected branch circuits is p, and at all temperatures between 0.degree. and 80.degree. C., in q of the PTC-protected branch circuits, where q is at least 0.1 p, the I.sub.DAMAGE of the branch connection means in that PTC-protected branch circuit is equal to or lower than I.sub.22, where I.sub.22 is the I.sub.DAMAGE of PVC-insulated copper wire having a cross-sectional area of 0.324 mm.sup.2 (22 AWG);
- or
- (D) some of the PTC-protected branch connection means are insulated copper wires having an I.sub.DAMAGE equal to or less than I.sub.22, and some of the PTC-protected branch connection means are insulated copper wires having an I.sub.DAMAGE greater than I.sub.22, where I.sub.22 is the I.sub.DAMAGE of a PVC-insulated copper wire having a cross-sectional area of 0.324 mm.sup.2 (22 AWG), and at all temperatures between 0.degree. and 80.degree. C., the total length of the PTC-protected branch connection means having an I.sub.DAMAGE greater than I.sub.22 is not more than x times the total length of the PTC-protected branch connection means in which I.sub.DAMAGE is equal to or less than I.sub.22, where x is 10.
22 more elements
An electrical system which is installed in a road vehicle, and which comprises
- (1) a battery;
- (2) a supply connection means which is electrically connected to a first pole of the battery, and which has, at its weakest current-carrying point, a current-carrying capacity of I.sub.LINK amps,
- (3) a return connection means which is electrically connected to a second pole of the battery;
- and
- (4) a plurality of PTC-protected branch circuits which are electrically connected in parallel between the supply connection means and the return connection means, each of said branch circuits comprising
- (a) a branch PTC circuit protection device which
- (i) is electrically connected to the supply connection means directly or via at least one other PTC-protected branch circuit,
- (ii) is taken from a batch of PTC devices made by the same manufacturing process, the largest steady state current which will not cause any of the devices in the batch to trip being I.sub.PASS and the smallest steady state current which will cause all of the devices in the batch to trip being I.sub.TRIP, I.sub.TRIP being less than I.sub.LINK, and
- (iii) contains a PTC element which is composed of a conductive polymer;
- (b) an operative electrical device which is spaced apart from the branch PTC circuit protection device;
- and
- (c) an elongate PTC-protected branch connection means which
- (i) electrically connects the branch PTC device and the operative device, and
- (ii) has at all points a current-carrying capacity of at least I.sub.DAMAGE amps, I.sub.DAMAGE being more than I.sub.TRIP ;
- whereby, if the PTC-protected branch connection means is accidentally connected to the first and second poles of the battery by connections which do not include the operative device, there is created a fault circuit which contains the branch PTC circuit protection device and in which the current is initially greater than I.sub.TRIP, thus causing the branch PTC circuit protection device to trip and reduce the current to a steady state value substantially below I.sub.TRIP ;
- in which system, the total number of PTC-protected branch circuits is p, and at all temperatures between 0.degree. and 80.degree. C., in q of the PTC-protected branch circuits, where q is at least 0.1 p, the I.sub.DAMAGE of the branch connection means in that PTC-protected branch circuit is equal to or lower than I.sub.22, where I.sub.22 is the I.sub.DAMAGE of PVC-insulated copper wire having a cross-sectional area of 0.324 mm.sup.2 (22 AWG).
13 more elements
An electrical system which is installed in a road vehicle, and which comprises
- (1) a battery;
- (2) a supply connection means which is electrically connected to a first pole of the battery, and which has, at its weakest current-carrying point, a current-carrying capacity of I.sub.LINK amps,
- (3) a return connection means which is electrically connected to a second pole of the battery;
- and
- (4) a plurality of PTC-protected branch circuits which are electrically connected in parallel between the supply connection means and the return connection means, each of said branch circuits comprising
- (a) a branch PTC circuit protection device which
- (i) is electrically connected to the supply connection means directly or via at least one other PTC-protected branch circuit,
- (ii) is taken from a batch of PTC devices made by the same manufacturing process, the largest steady state current which will not cause any of the devices in the batch to trip being I.sub.PASS and the smallest steady state current which will cause all of the devices in the batch to trip being I.sub.TRIP, I.sub.TRIP being less than I.sub.LINK, and
- (iii) contains a PTC element which is composed of a conductive polymer;
- (b) an operative electrical device which is spaced apart from the branch PTC circuit protection device;
- and
- (c) an elongate PTC-protected branch connection means which
- (i) electrically connects the branch PTC device and the operative device, and
- (ii) has at all points a current-carrying capacity of at least I.sub.DAMAGE amps, I.sub.DAMAGE being more than I.sub.TRIP ;
- whereby, if the PTC-protected branch connection means is accidentally connected to the first and second poles of the battery by connections which do not include the operative device, there is created a fault circuit which contains the branch PTC circuit protection device and in which the current is initially greater than I.sub.TRIP, thus causing the branch PTC circuit protection device to trip and reduce the current to a steady state value substantially below I.sub.TRIP ;
- in which system some of the PTC-protected branch connection means are insulated copper wires having an I.sub.DAMAGE equal to or less than I.sub.22, and some of the PTC-protected branch connection means are insulated copper wires having an I.sub.DAMAGE greater than I.sub.22, where I.sub.22 is the I.sub.DAMAGE of a PVC-insulated copper wire having a cross-sectional area of 0.324 mm.sup.2 (22 AWG), and at all temperatures between 0.degree. and 80.degree. C., the total length of the PTC-protected branch connection means having an I.sub.DAMAGE greater than I.sub.22 is not more than x times the total length of the PTC-protected branch connection means in which I.sub.DAMAGE is equal to or less than I.sub.22, where x is 10.
13 more elements
An electrical system which is installed in a road vehicle, and which comprises
- (1) a battery;
- (2) a supply connection means which is electrically connected to a first pole of the battery, and which has, at its weakest current-carrying point, a current-carrying capacity of I.sub.LINK amps,
- (3) a realm connection means which is electrically connected to a second pole of the battery;
- and
- (4) a plurality of PTC-protected branch circuits which are electrically connected in parallel between the supply connection means and the return connection means, each of said branch circuits comprising
- (a) a branch PTC circuit protection device which
- (i) is electrically connected to the supply connection means directly or via at least one other PTC-protected branch circuit,
- (ii) is taken from a batch of PTC devices made by the same manufacturing process, the largest steady state current which will not cause any of the devices in the batch to trip being I.sub.PASS and the smallest steady state current which will cause all of the devices in the batch to trip being I.sub.TRIP, I.sub.TRIP being less than I.sub.LINK, and
- (iii) contains a PTC element which is composed of a conductive polymer;
- (b) an operative electrical device which is spaced apart from the branch PTC circuit protection device;
- and
- (c) an elongate PTC-protected branch connection means which
- (i) electrically connects the branch PTC device and the operative device, and
- (ii) has at all points a current-carrying capacity of at least I.sub.DAMAGE amps, I.sub.DAMAGE being more than I.sub.TRIP ;
- whereby, if the PTC-protected branch connection means is accidentally connected to the first and second poles of the battery by connections which do not include the operative device, there is created a fault circuit which contains the branch PTC circuit protection device and in which the current is initially greater than I.sub.TRIP, thus causing the branch PTC circuit protection device to trip and reduce the current to a steady state value substantially below I.sub.TRIP ;
- in which system in at least one of the PTC-protected branch circuits,
- (i) at all temperatures between 0.degree. and 80.degree. C., the I.sub.PASS of the branch PTC device in that PTC-protected branch circuit is at least 1.1 times I.sub.LOAD, and
- (ii) at at least one temperature between -40.degree. and 85.degree. C., the I.sub.PASS of the branch PTC device in that PTC-protected branch circuit is at most 1.3 times I.sub.LOAD,
- where I.sub.LOAD is the maximum steady state current in that PTC-protected branch circuit under normal operation conditions.
16 more elements
An electrical system which is installed in a road vehicle, and which comprises
- (1) a battery;
- (2) a supply connection means which is electrically connected to a first pole of the battery, and which has, at its weakest current-carrying point, a current-carrying capacity of I.sub.LINK amps,
- (3) a return connection means which is electrically connected to a second pole of the battery;
- and
- (4) a plurality of PTC-protected branch circuits which are electrically connected in parallel between the supply connection means and the return connection means, each of said branch circuits comprising
- (a) a branch PTC circuit protection device which
- (i) is electrically connected to the supply connection means directly or via at least one other PTC-protected branch circuit,
- (ii) is taken from a batch of PTC devices made by the same manufacturing process, the largest steady state current which will not cause any of the devices in the batch to trip being I.sub.PASS and the smallest steady state current which will cause all of the devices in the batch to trip being I.sub.TRIP, I.sub.TRIP being less than I.sub.LINK, and
- (iii) contains a PTC element which is composed of a conductive polymer;
- (b) an operative electrical device which is spaced apart from the branch PTC circuit protection device;
- and
- (c) an elongate PTC-protected branch connection means which
- (i) electrically connects the branch PTC device and the operative device, and
- (ii) has at all points a current-carrying capacity of at least I.sub.DAMAGE amps, I.sub.DAMAGE being more than I.sub.TRIP ;
- whereby, if the PTC-protected branch connection means is accidentally connected to the first and second poles of the battery by connections which do not include the operative device, there is created a fault circuit which contains the branch PTC circuit protection device and in which the current is initially greater than I.sub.TRIP, thus causing the branch PTC circuit protection device to trip and reduce the current to a steady state value substantially below I.sub.TRIP ;
- in which system in at least one of the PTC-protected branch circuits,
- (i) at all temperatures between 0.degree. and 80.degree. C., the I.sub.DAMAGE of the branch connection means in that PTC-protected branch circuit is at least 1.1 times the I.sub.TRIP of the branch PCT device in that PTC-protected branch circuit, and
- (ii) at at least one temperature between -40.degree. and 85.degree. C., the I.sub.DAMAGE of the branch connection means in that PTC-protected branch circuit is at most 1.5 times the I.sub.TRIP, of the branch PTC device in that PTC-protected branch circuit.
15 more elements
Dependencies are inferred from the claim text.