Title:
CURRENT DETECTOR FOR CONTROL LOAD AND FAILURE DIAGNOSTIC UNIT EMPLOYING IT
Document Type and Number:
Japanese Patent JP3307005
Kind Code:
B2
Abstract:
PURPOSE: To enhance the current detection accuracy of a current detector and the abnormality detection accuracy of a failure diagnostic unit employing it.
CONSTITUTION: Current flowing through the heater 2 in an oxygen sensor 1 is detected by a current detection resistor 5 in the form of a voltage and amplified by means of a differential amplifier circuit 6 before it is converted into a digital value through an A/D converter 13. The A/D converter 13 provides a reference voltage VC for the differential amplifier circuit 6 as reference of the amplification. Resistors 8-11 constituting the amplifier circuit 6 have resistances being set so that (R1/R2)<(R3/R4) and thereby, the output voltage VOUT comes within the processing range of the A/D converter 13 when the heater 2 is not conducting. A microcomputor 14 updates the offset voltage based on the output voltage VOUT every time when the heater 2 is not conducting. When the heater 2 is conducted, the microcomputor 14 calculates the heater current iH using the offset voltage and judges the heater 2 to be abnormal.
Inventors:
Hiroyuki Ina
Yukihide Niimi
Toshiyuki Iwasaka
Yukihide Niimi
Toshiyuki Iwasaka
Application Number:
JP16190793A
Publication Date:
July 24, 2002
Filing Date:
June 30, 1993
Export Citation:
Assignee:
株式会社デンソー
International Classes:
G01N27/12; G01N27/26; G01R19/00; G01R19/25; G05F1/10; H03M1/12; (IPC1-7): G01R19/25; G01N27/12; G01N27/26; G01R19/00; G05F1/10; H03M1/12
Domestic Patent References:
| JP3165245A | ||||
| JP5134021A | ||||
| JP616775U | ||||
| JP224387U | ||||
| JP3121733U |
Attorney, Agent or Firm:
Hironobu Onda