JPH01200041A - Idle revolution speed controller for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent the generation of excess or shortage in the engine intake quantity by calculating the cooling water temperature from the intake quantity of a bypass passage which is opened and closed by a wax and determining an aimed idle revolution speed on the basis of the cooling water temperature, when a water temperature sensor is in fail. CONSTITUTION:During the operation of an engine 1, a control part 9 judges if an idle state exists or not, from the output of an idle switch 6, and in case of idle state, the water temperature information is read from the output of a water temperature sensor 4, and a aimed idle revolution speed is determined. Further, the water temperature sensor 4 judges fail-safe or not, and in case of fail-safe, the intake quantity information is read from the output of an air flow sensor 2. Then, the intake quantity of a branch 11b which is detected by a controller 9 is subtracted from the output of the air flow sensor 2, and the intake quantity of a branch 11a which is opened and closed by a wax 8 is calculated. The cooling water temperature is detected in correspondence to the intake quantity of the branch 11a, and the aimed idle revolution speed is determined on the basis of the cooling water temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an idle speed control device for an internal combustion engine.

[Conventional technology]

A flowchart showing the operation of a conventional idle speed control device for an internal combustion engine is shown in FIG. In step 20, the engine rotation speed is detected, and in step 21, it is detected whether the idle switch is on, that is, whether it is in the idle state,
If it is in the idle state, water temperature information is read in step 22. In step 23, it is determined whether the water temperature sensor has failed. Failure is determined when the output of the water temperature sensor shows a value that is impossible under common sense. If the water temperature sensor fails, in step 24 the water temperature is read as a predetermined value of high temperature Tt as the engine water temperature, and in step 25 the target idle rotation speed is calculated from the engine water temperature using the relationship shown in FIG. In step 26, the deviation between the target idle speed and the engine speed is calculated, and in step 27, the amount of movement of the actuator of the regulating valve that opens and closes the bypass passage for intake air of the engine is calculated in accordance with this deviation. In step 28, the actuator is actuated to adjust the regulating valve, thereby adjusting the amount of air flowing through the bypass passage.

In the conventional device described above, the water temperature is set to a high temperature when the water temperature sensor fails for the following reason.

The engine water temperature is high during most of the operating time, and the engine water temperature is low only during cold start and for a while afterwards. or,
If we control the water temperature by determining it as a low temperature T, and if it is actually high temperature, then the relationship between the engine water temperature and the optimal intake air amount is as shown in Figure 2 ■, where the lower the temperature, the larger the intake air amount. , the amount of intake air required to maintain the idle rotation becomes excessive, and the idle rotation speed increases as shown in Figure 4 (■).
Increased fuel consumption, Ensamp V-100 becoming less effective (no sense of deceleration), high engine noise, large shock during N-D shift in AT cars, large cleave, etc. This is because failures may occur. Note that FIG. 4 ■ is the same as FIG. 3.

[Problem to be solved by the invention]

As described above, in the conventional device, when the water temperature sensor fails, it is determined that the water temperature should be high, and the actuator of the bypass path regulating valve is controlled to supply the necessary amount of air at the high temperature. Therefore, if the actual water temperature is low,
The amount of air supplied is insufficient, and the engine cannot be supplied with enough air to maintain idle operation at that temperature.
As shown in FIG. 4 (■), there is a risk that the idle speed will become low, leading to the engine stalling, and in the worst case, the engine will not be able to start at low temperatures.

This invention was made in order to solve the above-mentioned problems, and provides an idle speed control device for an internal combustion engine that can normally control the idle speed when the water temperature sensor is installed. The purpose is to obtain.

[Means to solve the problem]

The idle speed control device for an internal combustion engine according to the present invention includes:
The apparatus is provided with a wax intake air amount calculation means for calculating the intake air amount due to wax by subtracting the intake air amount by the regulating valve from the output of the intake air amount detection means, and a cooling water temperature detection means for detecting the cooling water temperature from the wax intake air amount.

[Effect]

In this invention, when the water temperature sensor fails, the wax intake amount is calculated, the cooling water temperature is detected from this wax intake amount, and the target idle rotation speed is detected based on the detected cooling water temperature.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. 1st
The figure shows the configuration of this embodiment device, where l is an engine, 2 is an air flow sensor that detects the amount of intake air, 3 is a rotation speed sensor that detects the engine rotation speed, 4 is a water temperature sensor that detects the temperature of engine cooling water, 5 is a throttle valve provided in the intake pipe 10 to adjust the amount of intake air; 6 is an idle switch that detects an inactive state, that is, an idle state of the throttle valve 5; 11 is connected to the intake pipe 10 so as to bypass the throttle valve 5; This bypass path consists of shunt paths 11a and llb. 8 is a wax that automatically operates mechanically according to the temperature of the engine coolant to open and close the shunt 11a, 7 is a regulating valve that opens and closes the shunt tib, and 9 is an air flow sensor. 2,
Rotation speed sensor 3, water temperature sensor 4 and idle switch 6
This is a control section that controls the actuator of the regulating valve 7 according to the output of the control valve 7.

Next, the operation of the above device will be explained with reference to the flowchart shown in FIG. In step 20, the engine speed is calculated from the output of the rotation speed sensor 3, and in step 21, it is determined from the output of the idle switch 6 whether or not the engine is in an idle state.

In the case of the idle state, in step 22, the water temperature sensor 4
Read water temperature information from the output of . In step 23, it is determined whether or not the water temperature sensor 4 has failed in the same manner as in the past. If it has failed, the intake air amount information is read from the output of the air flow sensor 2 in step 29, and in step 3o, the controller 9 reads the intake air amount information from the output of the air flow center t2. Subtract the intake air amount of the shunt ttb detected by the shunt ILa by the wax 8.
Calculate the intake air amount.

The relationship between the cooling water temperature and the intake air amount in the shunt 11a is as shown in FIG. 2, and the cooling water temperature can be detected from the intake air amount in the shunt 11a. Therefore, in step 31, the shunt 11a
The cooling water temperature is detected from the intake air amount. In step 25,
The cooling water temperature and idle target rotational speed are calculated from the relationship shown in FIG. 3, and steps 26 to 28 are the same as in the prior art.

〔Effect of the invention〕

As described above, according to this invention, when the water temperature sensor fails, the water temperature of the Enson cooling water that has a predetermined relationship with the wax intake amount is detected, and it is possible to detect a water temperature that is close to the actual water temperature. This eliminates excess or deficiency in the intake air amount as in the past, and prevents an increase in noise, an increase in fuel consumption, a decrease in idling speed, and engine stalling.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the configuration of the device of this invention, Figure 2 is a diagram showing the relationship between cooling water temperature and intake air amount at idle, Figure 3 is a diagram showing the relationship between cooling water temperature and target rotational speed at idle, and Figure 4 is a diagram showing the relationship between cooling water temperature and the target rotational speed at idle. FIG. 5 is a flowchart showing the operation of the conventional device, and FIG. 6 is a flowchart showing the operation of the present invention device. ■... Engine, 2... Air flow sensor, 3...
・Rotational speed sensor, 4... Water temperature sensor, 6... Idle switch, 7... Adjustment valve, 8... Wax, 9...
...control unit, lO...intake pipe, 11...pi/cess passage.

Claims (1)

[Claims] An intake air amount detection means that detects the intake air amount of the engine, an idle state detection means that detects the idle state of the engine, a water temperature sensor that detects the engine cooling water temperature, and a wax that opens and closes the bypass path of the engine intake pipe according to the cooling water temperature. ,
A regulating valve that opens and closes the bypass passage, a rotational speed sensor that detects the engine rotational speed, a target idle rotational speed that is detected from the cooling water temperature, and a control valve according to the deviation between the target idle rotational speed and the engine rotational speed. In the idle speed control device for an internal combustion engine including a control unit, a wax intake amount calculation means for calculating an intake air amount due to wax by subtracting an intake air amount by a regulating valve from an output of an intake air amount detection means;
A cooling water temperature detection means for detecting the cooling water temperature from the wax intake amount and a fail detection means for detecting a failure of the water temperature sensor are provided, and when the water temperature sensor fails, the target idle rotation speed is detected from the output of the cooling water temperature detection means. An idle speed control device for an internal combustion engine, characterized by: