Device and method for determining intermittent short circuit

• US 20030142449A1
• Filed: 01/25/2002
• Published: 07/31/2003
• Est. Priority Date: 01/25/2002
• Status: Active Grant

• Current Assignee: Pacific Engineering Corporation (Stantec Incorporated)
• Original Assignee: Pacific Engineering Corporation (Stantec Incorporated)
• Inventors: Ohta, Manabu, Iwata, Toshinori
• Granted Patent: US 6,870,720 B2
• Time in Patent Office: Days
• US Class Current: 361/58
• CPC Class Codes: H01L 2224/45014 Ribbon connectors, e.g. rectangular cross-section
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48137 the bodies being arranged next to each other, e.g. on a common substrate
• CPC Class Codes: H01L 2224/4903 Connectors having different sizes, e.g. different diameters
• CPC Class Codes: H01L 2224/49113 the connectors connecting different bonding areas on the semiconductor or solid-state body to a common bonding area outside the body, e.g. converging wires
• CPC Class Codes: H01L 2224/49171 Fan-out arrangements
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/13091 Metal-Oxide-Semiconductor Field-Effect Transistor [MOSFET]
• CPC Class Codes: H01L 2924/181 Encapsulation
• CPC Class Codes: H01L 2924/3011 Impedance
• CPC Class Codes: H02H 1/0015 Using arc detectors
• CPC Class Codes: H02H 3/087 for dc applications
• CPC Class Codes: H02H 3/0935 the timing being determined by numerical means

Abstract

A miniaturized cost-saving intermittent short circuit determining device located between a power source and an electric load in a vehicle electric circuit. The determining device includes detecting means for detecting current flowing through the electric circuit, determining means for determining whether the current detected by the detecting means is an intermittent short circuit, and disconnecting means for disconnecting the electric circuit when the determining means judges that there is an abnormality. The determining means is connected to an external switch circuit, which selectively supplies and stops current to the electric load of the electric circuit. The determining means determines whether the external switch circuit is switched on or off, and switches the disconnecting means on or off according to the determination.

Claims

1. An intermittent short circuit determining device located between a power source and a load circuit in a vehicle electric circuit, the intermittent short circuit determining device compromising:

means for detecting current flowing through the load circuit;

means for determining whether the current detected by the detecting means is an intermittent short circuit;

means for disconnecting the load circuit when the determining means determines that there is an intermittent short circuit;

wherein the determining means is selectively connected to an external switch circuit, which supplies and stops current to the load circuit, and wherein the determining means determines whether the external switch circuit is switched on or off, and switches the disconnecting means on or off according to said determination.

2. The intermittent short circuit determining device according to claim 1, wherein a fuse is included in the detecting means.

3. The intermittent short circuit determining device according to claim 1, wherein a semi-conductor relay is included in the disconnecting means.

4. The intermittent short circuit determining device according to claim 1, wherein the detecting means, the determining means, and the disconnecting means are integrally packaged.

5. The intermittent short circuit determining device according to claim 1, wherein the detecting means is one of a plurality of detecting means, and each of the detecting means corresponds to a load circuit from a plurality of load circuits, respectively, wherein the disconnecting means is one of a plurality of disconnecting means, and each of the disconnecting means corresponds to a load circuit from said plurality of load circuits, respectively, wherein the determining means is connected to the plurality of detecting means and the plurality of disconnecting means, and the determining means is connected to a plurality of external switch circuits corresponding to the plurality of load circuits, respectively, and each external switch circuit selectively supplies and stops current to the load circuit, and wherein the determining means determines whether the plurality of external switch circuits are switched on or off, and selectively switches the disconnecting means on or off according to said determination.

6. The intermittent short circuit determining device according to claim 1, wherein the detecting means is one of a plurality of detecting means, and each of the detecting means corresponds to a load circuit from a plurality of load circuits, respectively, wherein the disconnecting means is connected between a power source and the plurality of detecting means, and the disconnecting means is able to stop load current supplied to all of the load circuits, and wherein the determining means is one of a plurality of determining means, and each determining means is selectively connected to one of a plurality of external switch circuits, and the plurality of external switch circuits corresponds to the plurality of load circuits, respectively, and each external switch circuit selectively supplies and stops current to the load circuit, and wherein each determining means determines whether the external switch circuit is switched on or off, and selectively switches the disconnecting means on or off according to said determination.

7. The intermittent short circuit determining device according to claim 1, wherein the detecting means is one of a plurality of detecting means, and each of the detecting means corresponds to a load circuit from a plurality of load circuits, respectively, wherein the disconnecting means is one of a plurality of disconnecting means, and each of the plurality of disconnecting means corresponds to a load circuit from the plurality of load circuits, respectively, and wherein the determining means is one of a plurality of determining means, and each determining means is selectively connected to one of a plurality of external switch circuits, and each external switch circuit from the plurality of external switch circuits corresponds to a load circuit from the plurality of load circuits, respectively, and each external switch circuit selectively supplies and stops current to the load circuit, and wherein each determining means determines whether the external switch circuit is switched on or off, and switches the disconnecting means on or off according to the determination.

8. The intermittent short circuit determining device according to claim 7, wherein each of the plurality of detecting means is connected to a corresponding separate power source, and each of the plurality of disconnecting means is able to stop the load current supplied from the corresponding power source.

9. An intermittent short circuit determining device for determining whether an intermittent short circuit has occurred in a load circuit, the intermittent short circuit determining device comprising:

means for detecting a load current flowing through the load circuit and for generating a detection signal;

determining means connected to the detecting means, wherein the determining means determines whether an intermittent short circuit has occurred based on the detection signal;

and disconnecting means connected to the determining means, wherein the disconnecting means stops supply of the load current to the load circuit when it is determined that an intermittent short circuit has occurred, wherein the determining means determines whether an intermittent short circuit has occurred based on at least one of four characteristic quantities, which include the load current flowing through the load circuit, a time period during which the load current exceeds a predetermined current threshold value, an ON-duty ratio indicating the ratio of a time period when the load current exceeds the current threshold value relative to a predetermined time period, and an actual over-current number indicating the number of times that the load current exceeds the current threshold value during a predetermined time period, and wherein the determining means switches the disconnecting means on or off according to said determination.

10. The intermittent short circuit determining device according to claim 9, wherein the detecting means, the determining means, and the disconnecting means are integrally packaged.

11. The intermittent short circuit determining device according to claim 9, wherein when at least two of the four characteristic quantities exceed predetermined reference values, the determining means determines that an intermittent short circuit has occurred.

12. The intermittent short circuit determining device according to claim 11, wherein the detecting means, the determining means, and the disconnecting means are integrally packaged.

13. The intermittent short circuit determining device according to claim 9, wherein the determining means includes a processing circuit which generates a current flow permission signal and a current shutdown signal wherein the current flow permission signal activates the disconnecting means and allows the load current to flow, and the current shutdown signal inactivates the disconnecting means and stops the load current.

14. The intermittent short circuit determining device according to claim 9, wherein the current threshold value is one of a plurality of current threshold values, and the plurality of current threshold values defines a plurality of load current ranges, and each of the plurality of load current ranges is associated with at least one of a reference ON-duty ratio and a reference over-current number, and the determining means compares the load current with the plurality of current threshold values and identifies a load current range wherein the load current belongs, and when at least one of the ON-duty ratio and the actual over-current number exceeds the corresponding reference value associated with the identified load current range, the determining means determines that an intermittent short circuit has occurred.

15. The intermittent short circuit determining device according to claim 14, wherein the determining means includes a storage device for storing the plurality of current threshold values and at lease one of the reference ON-duty ratio and the reference over-current number.

16. A method for determining the occurrence of an intermittent short circuit in a load circuit, wherein the method includes performing at least one of four comparing steps including a current comparison step, a time period comparison step, a duty ratio comparison step, and an over-current number comparison step, wherein the current comparison step comprises comparing the value of load current flowing through the load circuit with a current threshold value, the time period comparing step comprises comparing a time period during which the load current exceeds the current threshold value with a reference time period, the duty ratio comparison step comprises comparing an ON-duty ratio with a reference ON-duty ration, where the ON-duty ratio indicates the ratio of a time period during which the load current exceeds the current threshold value relative to a predetermined time period, and the over-current number comparison step comprises comparing an actual over-current number indicating the number of the times that the load current exceeds the current threshold value during the predetermined time period with a reference over-current number.

17. The determining method according to claim 16, wherein the current threshold value is one of a plurality of current threshold values, and the plurality of current threshold values defines a plurality of load current ranges, and each of the plurality of load current ranges is associated with at least one of the reference ON-duty ratio and the reference over-current number, wherein the current comparing step includes comparing the load current with the plurality of current threshold values and determining a load current range to which the load current belongs, and the determining method further includes determining that an intermittent short circuit has occurred when at least one of the ON-duty ratio and the actual over-current number exceeds the corresponding reference value associated with the determined load current range.

18. A method for determining the occurrence of an intermittent short circuit in a load circuit, wherein the method includes at least two of four comparing steps including a current comparison step, a time period comparison step, a duty ratio comparison step, and an overcurrent number comparison step, wherein the current comparison step comprises comparing the value of a load current flowing through the load circuit with a current threshold value, the time period comparing step comprises comparing a time period during which the load current exceeds the current threshold value with a reference time period, the duty ratio comparison step comprises comparing an ON-duty ratio with a reference ON-duty ratio, and the ON-duty ratio indicates the ratio of a time period during which the load current exceeds the current threshold value relative to a predetermined time period, and the over-current number comparison step comprises comparing an actual over-current number indicating the number of times that the load current exceeds the current threshold value during the predetermined time period with a reference over-current number.

19. The determining method according to claim 18, wherein the current threshold value is one of a plurality of current threshold values, and the plurality of current threshold values define a plurality of load current ranges, and each of the plurality of load current ranges is associated with at least one of the reference ON-duty ratio and the reference over-current number, wherein the current comparing step includes comparing the load current with the plurality of current threshold values and determining a load current range to which the load current belongs, and the determining method further includes determining that an intermittent short circuit has occurred when at least one of the ON-duty ratio and the actual overcurrent number exceeds the corresponding reference value associated with the determined load current range.

20. A method for determining whether an intermittent short circuit has occurred in a load circuit, the method compromising:

comparing a load current that flows in the load circuit with a first current threshold value;

comparing the load current with a second current threshold value, the second current threshold value being greater than the first current threshold value;

comparing a first time period, during which the load current exceeds the first current threshold value, with a first reference time period;

comparing a second time period, during which the load current exceeds the second current threshold value, with a second reference time period;

comparing an ON-duty ratio with a reference ON-duty ratio wherein the on-duty ratio is the ratio of a time period when the load current exceeds the second current threshold value relative to a predetermined time period; and

comparing an overcurrent number with a reference overcurrent number, wherein the overcurrent number is the number of times that the load current exceeds the second current threshold value during a predetermined time period.

21. The determining method according to claim 20, wherein the method further comprises:

determining that when the load current exceeds the first current threshold value and when the first time period exceeds the first reference time period, an intermittent short circuit has occurred;

determining that when the load current exceeds the second current threshold value and when the second time period exceeds the second reference time period, an intermittent short circuit has occurred;

determining that when the load current exceeds the second current threshold value and when the ON-duty ratio exceeds the reference on-duty ratio an intermittent short circuit has occurred; and

determining that when the load current exceeds the second current threshold value and when the actual over-current number exceeds the reference over-current number, and intermittent short circuit has occurred.