JPS6022034A - Engine-speed controlling method for internal-combustion engine - Google Patents

Abstract

PURPOSE:To stabilize rotation of an engine at the time of starting, by controlling an idling-speed control valve by way of feedback control such that a target value of current corresponding to the duty ratio is supplied to said control valve at the time of ordinary operation of the engine, but controlling the control valve by a relatively large duty ratio by interrupting the above feedback control at the time of starting the engine. CONSTITUTION:An electromagnetic idling-speed control valve 16 is disposed in a by-pass passage 14 which is extended to by-pass a throttle valve 8 and to communicate the upstream side of the throttle valve 8 and a surge tank 12 disposed on the upstream side of the throttle valve 8 with each other. In controlling the idling speed of an engine by controlling the control valve 16 by an electronic control circuit 44, a current detector 17 is provided for detecting the mean current passed through a solenoid of the control valve 16. At the time of ordinary operation of the engine, the solenoid of the control valve 16 is feedback-controlled such that the mean value of the above current passed through the solenoid is rendered equal to the target value corresponding to the duty ratio detected from the operational conditions of the engine. At the time of starting the engine, on the other hand, the above feedback control is interrupted and the solenoid is controlled by a duty ratio larger than the above duty ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling the rotation speed of an internal combustion engine, and in particular to a method for controlling the rotation speed of an internal combustion engine, in which a detour is provided to bypass a throttle valve, seven solenoid valves are provided, and a C
The present invention relates to a method for controlling the rotation speed of an internal combustion engine, which controls the engine rotation speed by controlling the opening degree of a solenoid valve.

In modern internal combustion engines, there is a trend to reduce the weight of the engine and to set the idle speed low in order to improve fuel efficiency.

For this reason, when idling, even if a slight load is applied, such as by turning on the IPEM, driving an electric fan, or operating the shift lever on an engine equipped with an automatic transmission, the engine speed will drop, causing the engine speed to drop. The engine speed may become unstable.

Furthermore, when deposits accumulate on the throttle valve due to changes over time, the engine speed gradually decreases and the engine speed during idle link becomes unstable.

For this reason, a detour is provided to bypass the throttle valve so that the throttle valve is fully closed T' and the vehicle speed is at a predetermined point (for example, 0).
~2.5 When +n/h is less than 1, that is, when idling, the air flowing through this detour is controlled to feed the engine speed to the target speed. There are known methods of controlling On this detour.

An idle rotation speed control valve fIsc Pulp, which is composed of a solenoid valve equipped with a linear solenoid, is installed, and the current flowing through the solenoid controls the duty ratio and the opening degree of the solenoid valve is controlled. The amount of air flowing through the engine is controlled, and the engine speed is controlled by feedback control so that the engine speed is near the target speed determined according to the engine load, shift position, etc. In addition.

Without feedback control 7, the ISC valve will remain at a predetermined abdominal position.

With the ISO pulp mentioned above, the opening degree is controlled when the electromagnetic force and spring force are balanced, so when the electrical resistance of the solenoid changes due to temperature changes, etc.
c Current stops flowing, making it impossible to control the IsC pulp to a predetermined opening degree. Therefore, the average frequency of the current flowing through the solenoid is detected.

It has been proposed to perform feed/drop control by correcting the duty ratio by 7 so that this average value becomes a target current value corresponding to the duty ratio.

However, when starting one engine, power is supplied to the starter, so the battery voltage decreases and the current supplied to the ISO loop decreases, and the current detector that detects the current flowing to the solenoid is also positive. Because it does not work properly, I
The SC pulp opening cannot be controlled accurately and the engine speed becomes unstable at startup. There was a problem.

The present invention has been made to solve the above problems, and I
An object of the present invention is to provide a method for controlling the rotational speed of an internal combustion engine, which can accurately control the opening degree of an SO pulp and also stabilize the engine rotational speed at startup.

In order to achieve the above object, the present invention bypasses the throttle valve and connects the throttle valve 111C, (tut) to the downstream side of the throttle valve. By controlling the duty ratio of the supplied LE flow and controlling the amount of air flowing to the detour, the engine speed is reduced by controlling the engine speed 151.
In the control method, the average value of the current supplied to the solenoid valve is detected and feedback control is performed so that the detected average value becomes a target current of 1 shift corresponding to the tute ratio, and the feedback control is performed when starting 1 engine. There is a configuration in which f1'# is configured to stop the control and perform control with an duty ratio larger than the duty ratio.

According to the above configuration of the present invention, the pulp opening degree can be accurately controlled because the feedback control field is controlled so that the target current value corresponds to the duty ratio during normal operation.

At the time of starting, the feedback control is stopped and the duty ratio is increased, so that the rotation at the time of starting can be stabilized without being influenced by the current detector and the battery voltage drop. This effect can be obtained.

Next, an example of an internal combustion engine 1y11 (engine) to which the present invention is applied will be explained with reference to FIG. This engine is equipped with an automatic transmission 7.

It is controlled by an electronic control circuit such as a microcomputer, and is equipped with an air flow meter 2 downstream of an air cleaner (not shown) to detect the amount of intake air. The air flow meter 2 includes a convention plate rotatably provided in the damping chamber, a measuring plate connected to the convention plate, and a potentiometer 4 for detecting the opening degree of the convention plate. Therefore, the amount of intake air,
It is determined from the intake air amount signal outputted from the potentiometer as the voltage r. [ζ An intake air temperature sensor 6 is provided near the air flow meter 2 to detect the intake air temperature [2] and output an intake air temperature signal.

A throttle valve 8 is arranged downstream of the air flow meter 2, and the throttle valve 8 is in a fully closed state (
An idle switch lO that is turned on at idle position @) is installed, and a surge tank 2 is provided downstream of the throttle valve 8. Also.

pir bypassing the throttle valve 8 and above the throttle valve;
1ull and throttle valve downstream side tank 12 and y
7'1. ing.

An SC valve 16 whose opening degree can be adjusted by controlling the excitation current of the solenoid is attached to this detour 4, and a current detector for detecting the average current of the solenoid is attached to this ISC pulp 16. 17 is installed. The surge tank 12 communicates with the combustion chamber of the engine 20 through an intake manifold 18 and an intake boat 22Y valve. That's right.

A fuel injection valve 24 is attached to each cylinder so as to protrude into the intake manifold 18.

The combustion chamber of the engine 20 is connected via an exhaust port 26 and an exhaust manifold 28 to a catalytic converter (not shown) filled with a three-way catalyst. A 0□ sensor 30 is attached to the exhaust manifold 28 for detecting the residual oxygen concentration in the exhaust gas and outputting an air-fuel ratio signal. An additional engine cooling water temperature sensor 34 is attached to the engine block 32 so as to penetrate through the block 32 and protrude into the water jacket.

This cooling water temperature sensor 34 detects the engine cooling water temperature and outputs a water temperature signal.

A spark plug 38 is attached to each cylinder so as to penetrate the cylinder head 36 of the engine 20 and protrude into the combustion chamber.

An electronic control circuit 4 configured with a microcomputer or the like is connected via a distributor 40 and an igniter 42.
Connected to 4. Inside the distributor 40, there are installed an oil/oil discrimination sensor 46 and a crank angle sensor 48, which each consist of a signal rotor fixed to the distributor shaft and a pickup fixed to the distributor housing. In the case of a 6-cylinder engine, the cylinder discrimination sensor 46 is, for example, 720
゜A cylinder discrimination signal is output for each CA, and the crank angle sensor 4
8 outputs an engine rotational speed signal every 30° CA, for example.

The electronic control circuit 44 also includes a key switch 50°, a neutral start switch 52. Air conditioner switch 54
．． A vehicle speed sensor 56 and a battery 58 are connected. The key switch 50 outputs a starter signal when starting the engine, the neutral start switch 52 outputs a neutral signal only when the transmission is in neutral reliability, and the air conditioner switch 54 outputs a starter signal when the engine is started. l], the air conditioner signal is output.

[The vehicle speed sensor 56 is composed of a magnet fixed to the speedometer cable, a reed switch, and a magnetically sensitive element, and outputs a vehicle speed signal in accordance with the rotation of the speedometer cable.

As shown in FIG. 2, the electronic control circuit 44 includes a central processing unit (CPU 160) and a read-only memory (ROM).
62. RAM 4゛Moo access memory + RAM) 64.
Backup RAM (BU-RAM) 66, input/output capotro 8. The analog-to-digital converter (ADC 170) and a data bus, control bus, etc. that connect these are included.

Cylinder discrimination signal, engine speed signal, idle switch] A fully open throttle signal from 0, an air-fuel ratio signal, a starter signal, a neutral signal, and an air conditioner signal are input. In addition, the input/output capotro 8 outputs to the drive circuit an ISC pulp control signal for controlling the opening degree of the SC pulp, a fuel injection signal for opening and closing the fuel injection valve, and an ignition signal for turning on and off the igniter. Meanwhile, the drive circuit controls the ISO pulp, the fuel injection valve, and the igniter in accordance with these signals. Further, the ADC 70 receives a pulp drive current, an intake air amount signal, an intake air temperature signal, a battery voltage, and a water temperature signal as input, and the ADC sequentially converts these signals into digital signals in accordance with instructions from the CPU. R
O=M62 contains data on the target rotation speed determined according to the engine cooling water temperature, intake temperature, load condition, shift lever range position, etc., and the expected amount for performing feedforward control when a load is applied. The target current value for the output duty ratio and other control programs are stored in advance.

Next, an embodiment in which the present invention is applied to the engine as described above will be described in detail.

FIG. 3 shows the middle of the main routine according to the present invention. In step 100, seven engine operating states are determined based on the air conditioner signal, neutral signal, etc., and the target rotation speed NF and B are determined according to the operating states. An expected duty ratio De corresponding to an expected air amount according to the operating state of the controller is set in a predetermined area of the RAM. [Next step] In step 02, it is determined whether the idle speed control (ISC) timing has come by determining whether it is every 120° CA, for example. When the ISC timing is reached, in step 104, the average engine speed 1i? is determined based on the engine speed signal. fNEYfH%
Then, in step 106, it is determined whether the feedback control conditions are satisfied. This feedback control condition is 5, for example, the throttle valve is fully closed, the vehicle speed is below a predetermined speed (for example, 2.5 Km/hl or less), and the engine cooling water temperature is above a predetermined temperature (for example, 70° C.).

If the feedback control condition is satisfied, in step 110, the basic duty ratio Do for feedback controlling the average injection of the engine speed to the target engine speed is calculated, and the feed is adjusted when a load is applied. Forward 1u1] Estimated duty ratio for controlling 1)e
is added to the basic duty ratio Do to calculate the control duty ratio.

In the next step 112, it is determined whether the learning control condition is satisfied or not.7. If it holds true, learning control is performed in step 114, and then the control duty ratio is set in the register as the output duty ratio])out in step 116. An example of this learning control is as follows.

One of them is a fixed time elapsed shift after feedback control.
The average value NE of the engine rotation speed is set to a predetermined value (for example, the target rotation speed NF).

Output duty ratio when the output duty ratio is within 25 r, p, ml 1) Gradually increase or decrease the learned value when the deviation between out and the learned value stored in BtJ-RAM is less than a predetermined value. This is a method to bring the learned value closer to ])out.
The first method is to constantly compare the average value NE of the engine rotation speed with the target rotation speed, and increase or decrease the number of learning shifts based on the magnitude relationship in order to bring the learned value closer to Dout.

Further, if it is determined in step 106 that the feedback control condition is not satisfied, in step 108, the control duty ratio is set to the duty ratio at the end of the feedback control or the learning value, and the ISO oven loop control is performed. and in step 116 this control tutee ratio D
Set Y output duty ratio Dout and set 1-.

FIG. 4 shows an interrupt routine that is executed every predetermined time (for example, 4m5ec) to control the ISO valve. In step 118, output a l5C-'' lube control signal to energize the ISC pulp solenoid;
In step 120, the ISO valve off time for demagnetizing the solenoid is calculated from the output duty ratio Dout, and in the first step 122, the off time is stored in the conveyor register. As a result, when the off time comes, the ISC solenoid demagnetizes.

As explained above, the basic duty ratio (basic duty ratio so that the average value of the engine rotation speed becomes the target rotation speed when the control condition is satisfied)).

When there is a change n and an expected duty ratio 1) e, the opening degree of the ISC pulp is controlled by adding the expected duty ratio. In addition, during automatic loop control,
Since the control duty ratio becomes a predetermined value, the iSC pulp opening degree is kept constant.

Next, with reference to FIG. 5, a routine for controlling the loop drive current kefeed bank will be described.

First, in step 124, it is determined whether or not it is time to start. Whether it is time to start or not is determined based on the starter signal and the engine speed, and when the starter signal is on or the engine speed is 1 predetermined value (for example).

When it is less than 500 r, pom, 3, it is determined that it is time to start.

When the engine is not starting, that is, the engine is completely exploded [7] and pu, step 128 is the valve drive flowing to the iSC pulp solenoid? The average value of the χ current is detected, and in step 130, a correction coefficient K is calculated that is proportional to the deviation between this 1(f) average 1111 of the current and the current value for the current output duty ratio. '.

Since the target current is directly proportional to the duty ratio, the larger the drop group from the target current for one cycle of detected current average, the larger δ is added to the correction coefficient. In the next step 132,
Step 108 (Step 1) Multiplies the control duty ratio determined by O by the correction transmission/convergence and outputs the duty ratio Dout.

As a result, the output duty ratio is corrected and the current flowing through the solenoid is controlled so as to reach the target value.

If it is determined at step 124 that it is time to start, then the process is started.

In step 126, the correction coefficient is set to a predetermined value of 1 or more (for example, 1.2), and the process proceeds to step 132.

Even if the correction coefficient K is set to a value of 1 or more, a battery voltage drop occurs due to starter drive at the time of starting, so the duty ratio is made larger than usual to compensate for the battery voltage drop. As a result of keeping the correction coefficient K constant as described above, the feedback control of the ISC valve drive current is stopped.

The changes in the output duty ratio Dout and the correction coefficient when the output voltage is controlled as described above will be explained with reference to FIG. At startup, the correction coefficient ■( is a constant value (1, 2
Since the output duty ratio Dout is set to 1, the output duty ratio Dout can also be kept constant. When the feedback 1b control of the valve drive current starts, the correction coefficient K changes gft to decrease toward 1, and the output duty ratio Dout changes accordingly as shown in the figure.

In addition, above I have explained an example in which the present invention is applied to an engine equipped with an automatic transmission, but the present invention is limited to this. Alternatively, the present invention can be applied to various types of engines, such as engines equipped with a pressure sensor that detects intake pipe pressure on the downstream side of the throttle valve.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing an example of an engine to which the present invention is applied, Fig. 2 is a block diagram showing the electronic control circuit of Fig. 1, and Fig. 3 is a main routine according to an embodiment of the present invention. FIG. 4 is a flow chart showing the 4m5ec interrupt routine of the above embodiment, FIG. 5 is a flow chart showing the routine for feedback control of the pulp drive current of the above embodiment, and FIG. FIG. 3 is a diagram showing changes in a correction coefficient and an output duty ratio. 14...Detour, 16...ISO valve, 44...
...Electronic control circuit, 50...Key switch.・9(・,゛1,− □,・) Engineering Fig. 3 Fig. 4

Claims (1)

[Claims] (1) A solenoid valve is provided in a detour route that bypasses the throttle valve and communicates the upstream side of the throttle valve with the downstream side of the throttle valve, and the duty ratio of the current supplied to the solenoid valve is controlled so that the electricity flows through the detour route. In an internal combustion engine rotation speed control method that controls the engine rotation speed by controlling the amount of electric current supplied to the solenoid valve, the average value of the electric current supplied to the solenoid valve (the average value detected by direct detection corresponds to the duty ratio) A method for controlling the rotation speed of an internal combustion engine, characterized in that feedback control is performed so that a target current value is achieved, and the feedback control is stopped when one engine is started, and control is performed at a duty ratio larger than the tutee ratio.