JPS6165046A - Method of controlling idle rotational speed of internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent engine-stalls and extraordinary drops in idle rotational speed of an engine, by controlling the amount of intake-air such that it is increased in accordance with the temperature of cooling water during a predetermined period after start of the engine, and then the increment of it is gradually decreased after lapse of the predetermined period. CONSTITUTION:Upon starting of an internal combustion engine, if the temperature of cooling water exceeds a predetermined temperature (P1), the amount of intake-air is controlled to be increased during a predetermined period after start of the engine (P2). After lapse of the predetermined period (P3) the increment of amount of intake-air is gradually decreased (P4). It is possible to prevent the lowering of torque of the engine caused by vapor which is generated in a fuel pipe line upon starting at a high temperature so that engine stalls and abnormal drops in idle rotational speed of the engine may be prevented. With this arrangement, the idle rotational speed is prevented from unreasonably increasing so that a stable idle rotational speed may be maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to an idle rotation fault suppression device for an internal combustion engine. The present invention relates to an idle speed control device for an internal combustion engine that prevents a decrease or fluctuation in speed.

[Prior art] By electrically controlling the opening degree of an idle speed control valve (hereinafter referred to as 15CV) provided in the bypass path of the throttle valve, the amount of air flowing bypassing the throttle valve is controlled to control the idle speed of the internal combustion engine. [S
The opening of the CV is clever ■.

[Problem to be Solved by the Invention 1] However, when an internal combustion engine is operated at high speed or under a high load for a long period of time and is then stopped and then started at a high temperature, the temperature of the engine may rise due to reasons such as stopping the cooling fan. As a result, the fuel thirst level in the fuel pipe increases abnormally, and vapor is generated in the fuel pipe 31. Therefore, when restarting in a high temperature condition, the fuel density decreases, the air-fuel ratio of the flooded air becomes extremely lean, the torque decreases, the rotation speed at idle becomes extremely unstable, the engine stalls, and the rotation speed decreases. There was a problem that caused an abnormal decrease in

Therefore, according to Japanese Patent Application Laid-Open No. 56-81230,
The fuel temperature is detected, and when the fuel temperature is higher than the set value, the amount of fuel injection is increased for a certain period of time from the time of starting, depending on the fuel temperature. It was proposed to prevent deterioration of drivability, but if there is no vapor generated in the fuel piping, the air-fuel ratio becomes excessively rich, causing problems such as worsening emissions in exhaust gas and worsening fuel efficiency. Ta.

[Means for Solving the Problems] The present invention has been made in consideration of the above points, and solves the above problems by having the following configuration.

That is, the method for determining the idle speed υj of an internal combustion engine according to the present invention is as follows:
As shown in FIG. 1, in a method for controlling the idle speed of an internal combustion engine in which a cooling water temperature of the internal combustion engine is detected and the amount of intake air is controlled using the cooling water temperature as one parameter, when the internal combustion engine is started, the cooling water is (If the temperature is above the predetermined temperature (Pl), the intake air amount is increased according to the cooling water temperature for a predetermined time after startup (P2) L, after a predetermined time (P3).
) is to gradually reduce the increase in the amount of intake air (P4), thereby preventing a decrease in torque due to vapor generation at high temperature startup, and reducing or stopping the opening/opening rotation speed. It can be prevented.

[Example] The present invention will be described below with reference to examples and drawings.

First, FIG. 2 is a schematic system diagram showing a four-stroke, four-cylinder internal combustion engine and its peripheral equipment in an embodiment to which the method of the present invention is applied.

1 is an engine, 2 is a piston, 3 is a spark plug, 4 is an exhaust manifold, 5 is provided in the exhaust manifold 4,
An oxygen sensor detects the residual oxygen concentration in exhaust gas, 6 is a fuel injection valve provided for each cylinder and injects fuel, 7 is an intake manifold, 7a is an intake manifold 7
7b is an intake valve, 8 is an intake air temperature sensor provided in the intake manifold 7 and detects 1 degree of intake air sent to the engine body 8, and 9 is a water temperature sensor that detects the engine cooling water temperature. , 10 is a throttle valve, 11 is a throttle position sensor that is linked to the throttle valve 10 and outputs a signal according to the opening degree of the throttle valve 10, 12 is a bypass passage that is an air passage that bypasses the throttle valve 10, and 13 is a bypass Road 12
An idle speed control valve (ISCV) controls the idle speed by controlling the frontage area, 14 represents an air meter 70 that measures the amount of intake air, and 15 represents an air cleaner that purifies the amount of intake air. Here, the above-mentioned 18cV13 is used in this embodiment to realize the idle rotation speed dynamic control method of the present invention, and is driven according to a control signal whose pulse duty ratio is controlled. Equipped with an electromagnetic solenoid that controls the opening area.

Further, 16 is an igniter that connects the ignition coil and outputs the high voltage necessary for ignition, and 17 is linked to a crankshaft (not shown) and distributes the high voltage generated by the igniter 16 to the spark plugs 3 of each cylinder. distributor, 18
19 is a rotation angle sensor that is installed in the distributor 17 and outputs 24 pulse signals for one revolution of the detripter 17, that is, two revolutions of the crankshaft; and 19 is a cylinder that outputs one pulse signal for one revolution of the distributor 17. The discrimination sensor and 20 each represent an electronic control circuit.

Next, FIG. 3 shows a block diagram of the electronic control circuit 20. As shown in FIG.

A central processing unit (CPU) 30 inputs and calculates data output from each sensor according to a control program, and performs processing to control the operation of various devices such as the fuel injection valve 6 and the igniter 16.
1 is a read-only memory (ROM) in which data such as the control program and a map for calculating the ignition advance angle are stored.
, 32 is a random access memory (RAM) in which data input to the electronic control circuit 20 and data necessary for the arithmetic control 2iI are temporarily read and written; 33 is a random access memory (RAM) in which data input to the electronic control circuit 20 and data necessary for the arithmetic control 2iI is temporarily read/written; A backup random access memory (backup RAM) backed up by a battery is used to store data necessary for the CPU 30, and 34 is an input port (not shown), a waveform shaping circuit provided as necessary, and an output signal from each sensor. Each of the figures represents an input section equipped with a multiplexer for selectively outputting signals, an A/D converter for converting an analog signal into a digital signal, and the like. 35 is provided with an output port in addition to an input port (not shown), and a fuel injection valve 6, an igniter 16, etc. are connected to the CP as necessary.
An input/output section 36 is provided with a drive circuit etc. that is driven according to a control signal from the CPU 30. The path lines connecting each element such as the ROM 31, the input section 34, and the output section 35 and through which each data is sent are shown.

The electronic i:, it sin circuit 20 takes in the detection data input from each sensor, calculates the optimal fuel injection amount and ignition timing according to the driving conditions, and when idling, it calculates the optimal fuel injection amount and ignition timing according to the driving conditions. The pulse duty ratio of the 1BII In signal is determined so that the engine speed matches the target speed, and this control signal is output to +5CV13 to control the opening degree of 15CV13 and control the idle speed.

Next, with reference to the flowcharts in Figures 4 and 5, CP
The idle rotation speed control processing routine executed by U30 will be explained.

FIG. 4 shows a part of the main routine. When entering this routine, first, in step 100, the rotation angle sensor 18 is
The engine rotation speed NE is calculated by counting the pulse signals sent from the engine. Next, in step 110, it is determined whether or not the flag X5TA, which is always set at the time of startup, is in the set state.
Proceed to step 20 and the engine speed NE at idle is 400.
It is determined whether or not the engine rotational speed NE reaches 400 [rJ)JO,], and steps 130 to 150 are executed.

That is, first, in step 130, flag
A series of processes such as determining the cooling water temperature as a parameter from a map as shown in FIG. 6 in which the duty ratio DHOT [%] is stored in the ROM 31 and is an increase correction term for the duty ratio of the control signal of l5CV13 at 0. Execute. Therefore, in the graph representing the map of FIG. 6, when the cooling water temperature is 80["C1 or higher, the duty ratio DHOT for the increase correction is set with the upper limit of 20%, so in step 150, the cooling water is When starting at a high temperature when the water temperature is 8.0 [℃] or higher, a duty ratio value corresponding to that temperature is recognized, and that value is RA ~ 132
will be stored within a predetermined area.

On the other hand, in step 120, the engine speed NE is 4.
00 [1:l), m, When judged as 1 or more,
Proceeding to step 170, the flag X5TA is reset to handle the processing of this routine, and when it is determined in step 101 that the flag is in the reset state, the process proceeds to step 160, where the engine speed NE is 300 [r, l
), 11. ] If the engine speed NE is less than 300 [r, p, m, ], steps 130 to 150 are executed in the same manner as above, and the duty ratio DHOT of the increase correction term is calculated.

This causes the engine to stall when starting at a high temperature, and the flag
It is also possible to deal with the case where the 5TA is started without being reset. On the other hand, if it is determined in step 160 that the engine speed NE is 300 [r, l), m, ] or more, the process in step 170 is executed and the process exits from this routine.

Next, FIG. 5 shows an interrupt routine that interrupts every 180 [' CAI of the crankshaft.
The pulse duty ratio given to the control signal of 13 as a control amount corresponding to the opening degree of l5CV13, that is, the amount of intake air is calculated.

When entering this routine, first, step 200 is executed, and the water duty ratio DQ is calculated based on the cooling water temperature and the engine rotation speed N.
E as a parameter, and then step 210
Counter value C that counts the time since startup
It is determined whether 3TA has reached 2 seconds or not, and if it is before 2 seconds, jumps to step 250, and executes step 200 above.
The final pulse duty ratio is calculated by adding the duty ratio DHOT of the increase correction term at the time of high temperature start calculated in step 150 of the main routine of FIG. 4 to the basic duty ratio Do obtained in step 1.

On the other hand, in step 210, when it reaches 2 seconds after starting, the process proceeds to the next step 220, and from the increase correction IDHOT 0.1 [
%], and in step 230, this increase correction term D
It is determined whether HCAT is 0 or more, and when the increase correction term DHOT is less than 0, it is set to O in step 240,
In other cases, the process directly proceeds to step 250, and the final pulse duty ratio is calculated by adding the increase correction term DHOT to the basic duty ratio DO. The pulse duty ratio calculated in this way is set in the counter of the input/output section 35, and is given as a control amount to the control signal (pulse signal) output to l5CV13.
The opening degree is controlled based on the pulse duty ratio,
15CV when starting at a high temperature when the cooling water temperature is 80 [C1 or higher]
13 is increased to increase the amount of intake air, thereby preventing torque from decreasing due to vapor generation at high temperatures. Furthermore, by repeatedly executing step 220, such an intake air amount increase control device is controlled to gradually reduce the amount of increase after 2 seconds have passed from the high temperature startup, and the cooling fan rotates to start the intake air amount. After that, the engine temperature gradually decreases, preventing the idle speed from increasing rapidly during a high temperature start.

In addition, in the above embodiment, the opening degree of the electromagnetic solenoid type ISC■ is controlled by the pulse duty ratio of the control signal, but in the 15CV using a step motor, the number of steps is calculated and the opening degree of rscv is controlled according to the number of steps in the same way as above. The amount of intake air is controlled to be 1 11H.

[Effects of the Invention] As explained above, according to the internal combustion Isoseki idle speed control method of the present invention, the intake air amount is controlled to increase for a certain period of time at the time of high temperature startup, and then the increased amount is gradually decreased. It is possible to prevent a torque drop during idling due to vapor generated in the fuel pipe during a high-temperature start, thereby preventing engine stalling and an abnormal drop in idling speed. Also,
At this time, it is possible to maintain a stable idle speed without increasing the idle speed pointlessly.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the present invention, FIGS. 2 to 6 show embodiments of the present invention, and FIG. 2 is a schematic block diagram including an internal combustion opening/closing control system to which the method of the present invention is applied. 3 is a block diagram of the electronic control circuit, FIGS. 4 and 5 are flowcharts showing the operation of the electronic control circuit, and the sixth factor is a graph showing the relationship between the cooling water temperature and the duty ratio DHOT of the additive correction term. 9...Water temperature sensor 12...Bypass path 13...
・l5CV 20...Electronic suburban circuit Figure 4 Figure 5

Claims (1)

[Scope of Claims] A method for controlling an idle rotation speed of an internal combustion engine, which detects a cooling water temperature of the internal combustion engine and controls an intake air amount using the cooling water temperature as one parameter, wherein when the internal combustion engine is started, the cooling water temperature is If the temperature is above a predetermined temperature, the intake air amount is controlled to increase according to the cooling water temperature for a predetermined time after startup, and after the predetermined time has elapsed, the increase in the intake air amount is gradually reduced. A method for controlling the idle speed of an internal combustion engine.