JPS606038A - Air-fuel ratio controller - Google Patents

Abstract

PURPOSE:To excellently relieve the load of a power source and to improve starting ability of an engine, by a method wherein a given state, such as during the starting of an engine, during reduction in the voltage of a power source, is detected to stop energization to a heater incorported in an air-fuel ratio sensor. CONSTITUTION:An analogue switch 10 stops energization to each part of a sensor control part 100 according to the operating condition of an engine, and an energization control circuit 11 controls a switch 10. The energization control circuit 11 monitors the presence of an operating signal STA of a starter switch, and the terminal voltage of a battery mounted on a car, the output voltage of a power source part to open the analogue switch 10 during operation of a starter and decrease in a given voltage to stop energization to a heater 5 and a sensor part 4. This prevents reduction in the voltage of a power source through shut off of a load such as the heater 5 when a large amount of a current is needed during the starting of an engine, and permits improvement of starting ability of an engine.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is an improvement of an air-fuel ratio control device that controls the air-fuel ratio of an air-fuel mixture to a target value by detecting the oxygen concentration contained in engine exhaust gas and feedback-controlling the fuel supply amount. It is related to.

Generally, by controlling the fuel supply amount so that the oxygen concentration contained in the exhaust gas becomes a predetermined value, the air-fuel ratio can be controlled to an optimal value. In this case, the air-fuel ratio sensor detects the oxygen concentration contained in the exhaust gas. This air-fuel ratio sensor differs depending on the type of sensor, but
If the temperature is not higher than 650'C, the oxygen concentration cannot be measured accurately.

Therefore, this senna with a built-in heater,
This is disclosed in Japanese Patent Application Laid-Open No. 57-140539. However, since this heater is always controlled to maintain a predetermined YAK a, when starting with a low battery voltage,
This resulted in a drop in voltage, and in severe cases, the spark plug could no longer ignite. In addition, since the heater is made of cotton, etc., the resistance value of the heater becomes small when the heater temperature is low, and a larger current flows than when the current is running, resulting in a fairly low voltage drop. was encouraging. In addition to the sensor that detects the stoichiometric air-fuel ratio of λ=1, this air-fuel ratio sensor also detects the lean side empty burst of λ>1 and generates an output current (so-called limit current) proportional to the oxygen concentration. Similar problems existed with other types of sensors.

In order to solve the second problem, the present invention detects a predetermined state such as when the engine is started or when the power supply voltage drops, and stops supplying electricity to the 1-keater built in the air-fuel ratio sensor. It is an object of the present invention to provide an air-fuel ratio control device that can improve the startability of an engine.

Hereinafter, the present invention will be explained with reference to embodiments shown in the drawings.

FIG. 1 shows a first embodiment of the invention. The air-fuel ratio control device in this embodiment can be roughly divided into an oxygen sensor control section 100
and an air-fuel ratio control device 200. The oxygen sensor Ili control unit 100 has a determination circuit 1 that receives the operating state signal P as input, determines whether the exhaust gas temperature is high or low, and sends out a determination signal Q. In this case, the driver's license credit%
P may be, for example, a 1 m rotational speed signal of the engine, a fuel injection ratio of 1<Russ, an intake air amount, or an intake negative pressure of 1. A combination of these signals, the opening signal of the diaphragm button, and the opening signal of the diaphragm button is used. 2 is a resistor 3 and an air-fuel ratio sensor connected between both ends of a power source (battery) 6 via a heater 5 of an oxygen sensor 4; It is closed only when the discriminating signals W and Q1 indicating that 7 is an analog switch connected across the switch 2 via a resistor 8;
&1 to U [closes only when 4'II separate signal Q2 indicating that the temperature is high is sent. 9 is sink 7 included i
The flow control circuit controls and integrates the current flowing into the sensor section of the oxygen sensor in relation to the exhaust temperature discrimination signal supplied from the c1 discrimination circuit 1.

In the engine air-fuel ratio control device configured as described above, the sensor section 4 detects the oxygen concentration contained in the engine's () [outgas] and sends the oxygen concentration signal 1 to the air-fuel ratio control section 2.
Supply to 00. The air-fuel ratio control unit 200 performs calculations to obtain the optimum air-fuel ratio based on oxygen concentration signal), engine rotational speed, air flow meter output signal, cooling water temperature, etc. Each time the fuel injection amount is controlled using the fuel injection valve, soid pack control is performed so that the optimum operating condition can be obtained.

On the other hand, discrimination 1iiJ lfP+ I Let i! l!
4J Co state (i Tsukasa'I' manually) 1 Discriminate the air temperature, for example (I! In operation in the load range, it is determined that the low exhaust is 6μ degrees and low temperature determination borrow (, 11. When the low temperature determination signal Q1 is sent out, only the switch 2 is closed, and the output of the power supply 6 is supplied to the heater 5 only through the resistor 3, and the heater 5 is supplied with a high voltage. Power leaf 1
1 is added to increase the amount of heat generated by the heater 5.

Next, when the engine is operated in a high load range, the special circuit 1 determines that the temperature is at the commercial exhaust temperature and sets the Ai MA
When the 6-high d1 discrimination signal Q2 that transmits the discrimination signal Q2 is transmitted, the switch 7 is closed and the output of the electric current i+/Ijc is supplied to the heater 5 via 8.3. As a result, the voltage applied to the heater 5 is equal to the voltage drop across the resistor 8 (+!
In addition to this, the amount of heat generated by the ζ heater 5 decreases. Therefore, since the sensor section 4 is always maintained at a substantially constant temperature regardless of the exhaust temperature that changes depending on the operating condition, the M(JQ: -1! sensor has a stable output that is not affected by temperature changes due to the exhaust temperature). You will get it.

Further, IO is a control switch for stopping energization to each part of the sensor control unit 100 depending on the engine condition, and 11 is an energization control circuit for controlling this switch 10. This energization control circuit 1] is the activation signal for the starter switch (not shown)! It monitors the terminal voltage of the S'VA, the terminal voltage of the on-board battery, the output voltage of the power supply 81, etc., and activates the analog 1'1 switch when the starter is activated (when starting the twin engine) and when the predetermined voltage is low. When the heater 5 and the sensor JJi7t (4, etc.) are not energized by opening the lO, the anodes R1 and D10 are always closed.

Kneading generates a large amount of current (electricity), such as when starting an engine.
When necessary, by cutting off the 1" 1 load such as the heater 5, a low power supply voltage can be prevented, and the engine start
Having the same gender, the whole thing becomes i+J ability.

Note that air-fuel ratio sensors No. 4 and 1, for example, Japanese Patent Application Laid-Open No. 57-48
G48 publication, Japanese Patent Application Publication No. 57-140539 +K,
This structure is already known from Japanese Patent Laid-Open No. 57-192852'j.

Next, FIG. 2 shows a second embodiment of the present invention. In this embodiment, the discrimination circuit 1 shown in the ¥81 embodiment is included in the discrimination circuit 1△.
It is designed to provide both the function of 1 and the function of the energization control circuit 110. When e = and h, the discrimination circuit IA detects them when the engine is started or when the power supply voltage is A or F, and sends a signal to open both analog switches 2.7:
is generated, and the energization of the heater 5-1 is stopped. J: I'm using sea urchins. However, in this example, the power supply to the heater 11 is stopped]
2, the energization to the sensor portion of the air-fuel ratio sensor 4, etc. will continue as is.

In this embodiment, the determination at the time of starting the engine is made by using the starter operation signal, but it may also be indirectly detected by the engine rotational speed.

As described above, in the present invention, when the engine is started or when the electrical voltage drops, the a-power to the heater built in the air-fuel ratio sensor is stopped in a predetermined state, so that the predetermined It is possible to satisfactorily reduce the negative effects on the power supply when the engine is in the state, and it becomes possible to further improve the startability of the engine.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a first embodiment of the invention, and FIG. 2 is a Zorrock diagram C showing a second embodiment of the invention. ■...fil separate episode +1A, 2. 7. 1 (1...
Analog τ1 switch, 4... Air-fuel ratio sensor, 5...
Heater, 6...Power supply. 9... Current control circuit, 11... Energization control circuit, 1 (
Hl...Sensor control unit, 2(1(1...Air-fuel ratio control unit.

Claims (1)

[Scope of Claims] (1) An air-fuel ratio control device having an air-fuel ratio sensor with a built-in heater in the exhaust system of the engine, and controlling the engine state according to the output of the air-fuel ratio sensor, An air-fuel ratio: 1+q control device, comprising means for stopping energization to the heater when the heater is in a predetermined state. (The air-fuel ratio control device according to claim 1 rfi, characterized in that the 21nil notation means is configured to stop energization of the heater ＼ when the engine is started. (3) The means includes: The air-fuel ratio M I++ according to claim 1, wherein the air-fuel ratio M I++ is configured to stop energizing the heater when the power supply voltage decreases.
Device.