Control apparatus

Patent metadata

Field	Value
Publication number	US-10048240-B2
Application number	US-201514849910-A
Country	US
Kind code	B2
Filing date	Sep 10, 2015
Priority date	Sep 23, 2014
Publication date	Aug 14, 2018
Grant date	Aug 14, 2018

Abstract

A control apparatus that controls a gas concentration sensor includes a sweep circuit, a current detection resistor, and a calculation portion. The sweep circuit supplies the gas concentration sensor with a sweep current. The calculation portion calculates impedance of the gas concentration sensor. The gas concentration sensor and the current detection resistor are sequentially connected in series along a direction from the sweep circuit to a reference voltage. The sweep circuit has a constant voltage circuit and a reference resistor. An increasing and decreasing tendency of a manufacturing variation of the reference resistor and an increasing and decreasing tendency of a manufacturing variation of the current detection resistor are identical. The calculation portion divides a product of a resistance value of the current detection resistor and a time variation of applied voltage to the gas concentration sensor by a time variation of applied voltage to the current detection resistor.

First claim

What is claimed is:

1. A control apparatus that controls a gas concentration sensor, the control apparatus comprising:
a sweep circuit supplying the gas concentration sensor with a sweep current having a current value temporally fluctuating, by temporally fluctuating applied voltage;
a current detection resistor detecting a current flowing through the gas concentration sensor; and
a calculation portion calculating an impedance of the gas concentration sensor,
wherein:
the gas concentration sensor and the current detection resistor are sequentially connected in series along a direction from the sweep circuit to a source of a reference voltage that has constant voltage;
the sweep circuit has a constant voltage circuit and a reference resistor;
the sweep current of the sweep circuit depends on constant voltage outputted from the constant voltage circuit and a resistance value of the reference resistor;
an increasing and decreasing tendency of a manufacturing variation of the reference resistor and an increasing and decreasing tendency of a manufacturing variation of the current detection resistor are identical;
the calculation portion divides a product of a resistance value of the current detection resistor and a time variation of applied voltage to the gas concentration sensor by a time variation of applied voltage to the current detection resistor, so that the impedance of the gas concentration sensor is calculated;
the resistance value of the reference resistor is expressed as Rref;
the increasing and decreasing tendency of the manufacturing variation of the current detection resistor corresponds to a manufacturing error of the current detection resistor;
a manufacturing error of the reference resistor is expressed as ΔRref;
the resistance value of the current detection resistor is expressed as Rs;
the manufacturing error of the current detection resistor is expressed as ΔRs;
the reference resistor and the current detection resistor are provided so that a relation expressed as: ΔRref/Rref=ΔRs/Rs, is established;
voltage between the sweep circuit and the gas concentration sensor is expressed as V 1 ;
voltage of the current detection resistor on a side of the gas concentration sensor is expressed as V 2 ;
voltage of the current detection resistor on a side of the reference voltage is expressed as V 3 :
a time variation of V 1 is expressed as d(V 1 );
a time variation of V 2 is expressed as d(V 2 );
a time variation of V 3 is expressed as d(V 3 ); and
the calculation portion
stores Rs,
detects d(V 1 ), d(V 2 ), and d(V 3 ), and
calculates Rs×(d(V 1 )−d(V 2 ))/(d(V 2 )−d(V 3 )),

so that the calculation portion calculates the impedance of the gas concentration sensor.

2. The control apparatus according to claim 1 , wherein:
the sweep current is expressed as Iopr;
a time variation of the sweep current Iopr is expressed as d(Iopr); and
the calculation portion
stores Rs and d(Iopr),
detects d(V 1 ) and one of d(V 2 ) and d(V 3 ), and
calculates the impedance of the gas concentration sensor.

3. The control apparatus according to claim 2 , wherein:
the calculation portion
detects d(V 1 ) and d(V 2 ),
calculates Rs×(d(V 1 −d(V 2 ))/(Rs×d(Iopr)), and
calculates the impedance of the gas concentration sensor.

4. The control apparatus according to claim 2 , wherein:
the calculation portion
detects d(V 1 ) and d(V 3 ),
calculates Rs×(d(V 1 )−(d(V 3 )−Rs×d(Iopr))/(Rs×d(Iopr)), and
calculates the impedance of the gas concentration sensor.

5. The control apparatus according to claim 2 , wherein:
the calculation portion
detects d(V 1 ) and d(V 2 ),
calculates Rs×(d(V 1 )−d(V 2 ))/(Rs×d(Iopr)), and
calculates the impedance of the gas concentration sensor.

6. The control apparatus according to claim 2 , wherein:
the calculation portion
detects d(V 1 ) and d(V 3 ),
calculates Rs×(d(V 1 )−(d(V 3 )−Rs×d(Iopr))/(Rs×d(Iopr)), and
calculates the impedance of the gas concentration sensor.

7. The control apparatus according to claim 1 , further comprising:
a reference circuit generating the reference voltage,
wherein:
the gas concentration sensor and the current detection resistor are sequentially connected in series along a direction from the sweep circuit to the reference circuit.

8. The control apparatus according to claim 1 , wherein:
the sweep circuit enables to change a maximum current value and a minimum current value of the sweep current.

9. The control apparatus according to claim 1 , wherein:
the current detection resistor and the reference resistor are provided on an identical semiconductor chip.

10. The control apparatus according to claim 1 , wherein:
the current detection resistor is a network resistor that is provided by combining a plurality of resistors into one piece; and
the reference resistor is a network resistor that is provided by combining a plurality of resistors into one piece.

11. A control apparatus that controls a gas concentration sensor, the control apparatus comprising:
a sweep circuit supplying the gas concentration sensor with a sweep current having a current value temporally fluctuating, by temporally fluctuating applied voltage;
a current detection resistor detecting a current flowing through the gas concentration sensor; and
a calculation portion calculating an impedance of the gas concentration sensor,
wherein:
the gas concentration sensor and the current detection resistor are sequentially connected in series along a direction from the sweep circuit to a source of a reference voltage that has constant voltage;
the sweep circuit has a constant voltage circuit and a reference resistor;
the sweep current of the sweep circuit depends on constant voltage outputted from the constant voltage circuit and a resistance value of the reference resistor;
an increasing and decreasing tendency of a manufacturing variation of the reference resistor and an increasing and decreasing tendency of a manufacturing variation of the current detection resistor are identical;
the calculation portion divides a product of a resistance value of the current detection resistor and a time variation of applied voltage to the gas concentration sensor by a time variation of applied voltage to the current detection resistor, so that the impedance of the gas concentration sensor is calculated;
the resistance value of the current detection resistor is expressed as Rs;
the sweep current is expressed as Iopr;
voltage between the sweep circuit and the gas concentration sensor is expressed as V 1 ;
voltage of the current detection resistor on a side of the gas concentration sensor is expressed as V 2 ;
voltage of the current detection resistor on a side of the reference voltage is expressed as V 3 ;
a time variation of the sweep current Iopr is expressed as d(Iopr);
a time variation of V 1 is expressed as d(V 1 );
a time variation of V 2 is expressed as d(V 2 );
a time variation of V 3 is expressed as d(V 3 ); and
the calculation portion
stores Rs and d(Iopr),
detects d(V 1 ) and one of d(V 2 ) and d(V 3 ), and
calculates the impedance of the gas concentration sensor.

Assignees

• Denso Corp

Inventors

• Nishimoto Satoshi
• Umeno Masafumi
• Yamada Yuji

Classifications

• G01N33/0073 Primary

  Control unit therefor · CPC title

• G01N27/045

  Circuits (measuring resistance per se G01R27/00, e.g. G01R27/22) · CPC title

• G01N27/028 Primary

  Circuits therefor (measuring impedance per se G01R27/02) · CPC title