Protector for electricity supply circuit

Patent metadata

Field	Value
Publication number	US-10700511-B2
Application number	US-201414513346-A
Country	US
Kind code	B2
Filing date	Oct 14, 2014
Priority date	Apr 24, 2012
Publication date	Jun 30, 2020
Grant date	Jun 30, 2020

Abstract

A protector for an electricity supply circuit includes: a power switch for switching between connection and disconnection of the electricity supply circuit; a controller configured to output a switching command signal to the power switch in accordance with an input signal; and a current detector for detecting current flowing to the electricity supply circuit. The controller includes: a lower limit threshold determination unit configured to determine whether or not an estimated temperature of a power line has dropped below a lower limit threshold; a timer for counting the time that passes after a load has been turned off, when the load is turned off by the power switch; and a mode switching unit configured to switch the controller to a sleep mode when a predetermined time is counted by the timer and the lower limit threshold determination unit determines that the estimated temperature has dropped below the lower limit threshold.

First claim

What is claimed is:

1. A protector for an electricity supply circuit including a power line, the protector installed on a vehicle to monitor a temperature of the power line connected to a load and configured to disconnect the electricity supply circuit when the temperature of the power line exceeds a preset threshold temperature, the protector comprising:
a power switch configured to switch between connection and disconnection of the electricity supply circuit to the load;
a controller configured to output a switching command signal to the power switch in accordance with an input signal from an operation switch; and
a current detector configured to detect current flowing to the power line,
wherein the controller comprises:
a temperature estimation unit configured to estimate temperature increase of the power line based on the current detected by the current detector and conducting time when the electricity supply circuit is connected to the load, estimate temperature decrease of the power line based on an elapsed time when the electricity supply circuit is disconnected from the load by the controller, and estimate a temperature of the power line based on the temperature increase and the temperature decrease;
a timer configured to count an elapsed time after the disconnection of the electricity supply circuit from the load by the power switch;
a lower limit threshold determination unit configured to determine that the estimated temperature of the power line estimated by the temperature estimation unit has dropped below a predetermined temperature determined by an ambient temperature of the power line; and
a mode switching unit configured to switch the controller to a low power consumption mode in which power consumption of the controller is lower than the power consumption in a normal operation mode of the controller, in response to the elapsed time counted by the timer being greater than a predetermined time and the lower limit threshold determination unit determining that the estimated temperature of the power line estimated by the temperature estimation unit drops below the predetermined temperature, wherein

at least a part of the power line is heated by high temperature air from an engine in an engine room of the vehicle, and
the predetermined time is determined based on the temperature increase of the power line by the high temperature air when forced air cooling operation of the engine room is stopped during the disconnection of the power switch.

2. The protector for the electricity supply circuit according to claim 1 , wherein
the temperature estimation unit does not estimate the temperature of the electricity supply circuit when the operation is switched to the low power consumption mode by the mode switching unit.

3. The protector for the electricity supply circuit according to claim 1 , wherein the mode switching unit switches the controller to the low power consumption mode in response to the elapsed time being greater than the predetermined time and the estimated temperature of the electricity supply circuit being lower than the predetermined temperature occurring at a same time.

Assignees

• Yazaki Corp

Inventors

• Nakamura Yoshihide
• Maruyama Akinori
• Ueta Keisuke

Classifications

• H02H6/00 Primary

  Emergency protective circuit arrangements responsive to undesired changes from normal non-electric working conditions using simulators of the apparatus being protected, e.g. using thermal images · CPC title

• H02H5/04 Primary

  responsive to abnormal temperature {(specially adapted for electric machines H02H7/0852)} · CPC title

• G06F1/26

  Power supply means, e.g. regulation thereof (for memories G11C) · CPC title

• H02H7/226

  for wires or cables, e.g. heating wires · CPC title

• H02H3/085

  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) · CPC title