Load drive apparatus and sensor control apparatus

Patent metadata

Field	Value
Publication number	US-9752958-B2
Application number	US-201414481210-A
Country	US
Kind code	B2
Filing date	Sep 9, 2014
Priority date	Sep 10, 2013
Publication date	Sep 5, 2017
Grant date	Sep 5, 2017

Abstract

A load drive apparatus ( 1 ) includes a pulse drive circuit ( 51 ) which applies a pulse voltage PS to a resistive load ( 4 ); current detection means (S 14 ) for detecting the current flowing to the resistive load ( 4 ) through the pulse drive circuit ( 51 ); level detection means (S 1, S 7 ) for determining whether an output terminal voltage VD of the pulse drive circuit ( 51 ) is a high potential level or a low potential level; anomaly detection means (S 8, S 9, S 18 ) for detecting a wire breakage anomaly, a short-to-power anomaly, and a short-to-ground anomaly based on the level of the output terminal voltage VD detected by the level detection means (S 1, S 7 ) and the current detected by the current detection means (S 14 ), when the pulse drive circuit 51 is turned on and off.

First claim

What is claimed is:

1. A load drive apparatus comprising:
a pulse drive circuit which has an output terminal connected to a second end of a resistive load whose first end is grounded, the pulse drive circuit being disposed between the resistive load and a power supply, the pulse drive circuit repeatedly applying a pulse voltage to the resistive load by repeatedly turning the pulse drive circuit on and off;
current detection means for detecting a current flowing from the power supply to the resistive load through the pulse drive circuit when the pulse drive circuit turns on;
level detection means for determining whether an output terminal voltage at the output terminal of the pulse drive circuit is at a high potential level or a low potential level; and
anomaly detection means for detecting a wire breakage anomaly, a short-to-power anomaly, and a short-to-ground anomaly based on the level of the output terminal voltage detected by the level detection means and the current detected by the current detection means when the pulse drive circuit is turned on and off,
the wire breakage anomaly being an anomaly in which at least one of a first connection path which connects the output terminal of the pulse drive circuit and the second end of the resistive load and a second connection path which grounds the first end of the resistive load is broken,
the short-to-power anomaly being an anomaly in which the first connection path is short-circuited to a power supply potential, and
the short-to-ground anomaly being an anomaly in which the first connection path is short-circuited to a ground potential.

2. The load drive apparatus as claimed in claim 1 , wherein the anomaly detection means includes:
wire-breakage determination means for determining that a wire breakage anomaly has occurred, when the level of the output terminal voltage changes between the high potential level and the low potential level as a result of turning the pulse drive circuit on and off, and the current flowing to the resistive load detected by the current detection means when the pulse drive circuit is turned on is smaller than a predetermined lower limit current value;
short-to-power determination means for determining that a short-to-power anomaly has occurred, when the level of the output terminal voltage remains at the high potential level irrespective of turning the pulse drive circuit on and off; and
short-to-ground determination means for determining that a short-to-ground anomaly has occurred, when the level of the output terminal voltage remains at the low potential level irrespective of turning the pulse drive circuit on and off.

3. The load drive apparatus as claimed in claim 1 , wherein the anomaly detection means comprises energization period anomaly detection means for detecting a wire breakage anomaly, a short-to-power anomaly, and a short-to-ground anomaly by turning the pulse drive circuit on and off during a pulse energization period during which the pulse voltage is repeatedly applied to the resistive load.

4. The load drive apparatus as claimed in claim 1 , further comprising energization stoppage means for stopping the supply of electric current to the resistive load by the pulse drive circuit when the anomaly detection means detects any of a wire breakage anomaly, a short-to-power anomaly, and a short-to-ground anomaly.

5. A sensor control apparatus which comprises the load drive apparatus as claimed in claim 4 , said sensor control apparatus controlling a sensor including a heater which is the resistive load and which generates heat when energized by the load drive apparatus and a detection element formed of solid electrolyte and heated by the heater, the sensor control apparatus comprising:
an element drive circuit for driving the detection element of the sensor; and
element drive stoppage means for stopping the drive of the detection element by the element drive circuit when the anomaly detection means of the load drive apparatus detects any of a wire breakage anomaly, a short-to-power anomaly, and a short-to-ground anomaly.

6. The sensor control apparatus according to claim 5 , wherein the sensor is a gas sensor which has, as the detection element, a gas detection element including a pump cell which is formed of an oxygen-ion-conductive solid electrolyte and pumps oxygen into or out of a measurement chamber of the gas detection element in accordance with a pump current flowing through the pump cell;
the element drive circuit includes a pump current control circuit for supplying the pump current to the pump cell; and
the element drive stoppage means includes pump current stoppage means for causing the pump current control circuit to stop the supply of the pump current to the pump cell.

Assignees

• Ngk Spark Plug Co

Inventors

• Yazawa Katsunori
• Inoue Yoshinori

Classifications

• G01R31/50

  Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections (testing of sparking plugs H01T13/58) · CPC title

• H02M3/156

  with automatic control of output voltage or current, e.g. switching regulators · CPC title

• Y02T10/40

  Engine management systems · CPC title

• F01N2560/20

  Sensor having heating means · CPC title

• F01N2550/00

  Monitoring or diagnosing the deterioration of exhaust systems · CPC title