JPH01253542A - Control device for number of idle revolution of engine - Google Patents

Abstract

PURPOSE:To always make the accurate control of idle revolution possible in an engine having an intake air quantity control valve and a flow rate control valve which are provided in series on a bypass intake passage bypassing a throttle valve by making the control characteristics of an intake air quantity control valve variable according to the opening to the flow rate control valve. CONSTITUTION:An intake air quantity control valve 8, which is controlled in its opening and closing at least during the idle operation of an engine and changes the intake air quantity on the basis of previously established control characteristics, is provided on a bypass intake passage 7 connected to the middle of an intake passage with a detour made round a throttle valve (not shown in a figure). In addition, a flow rate control valve 23 to control intake air flow rate according to cooling water temperature is provided on the downstream of the valve 8, and the valves 8, 23 are controlled to keep the number of idle revolutions at its target value. The above-mentioned device is provided with a varying means A to make the control characteristics of the valve 8 variable for varying the intake quantity control characteristics of the valve 8 according to the opening of the valve 23.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an engine idle speed control device.

(Prior Art) An electronically controlled idle speed control device, which has been widely used in automobile engines in recent years, forms a bypass passage for intake air so as to bypass, for example, a throttle valve of the engine, and also includes a throttle valve in this bypass passage. An intake air amount adjusting means (usually composed of a current-controlled solenoid valve) is provided to adjust the intake air amount in the minimum opening state (idle state) of the The intake air m adjusting means is electrically feedback corrected and controlled in accordance with the amount of deviation of the rotation speed from the frame rotation speed, thereby operating at the set idle target rotation speed.

In addition, in such an idle speed control device, even when an external load such as an engine load (for example, an air conditioner, etc.) is applied, the duty ratio of the solenoid valve is increased in response to the load amount. This prevents the rotation from decreasing and keeps the engine speed at the constant idle speed.

By the way, the above-mentioned intake air ff1l adjustment means does not necessarily always operate normally, and failures due to valve sticking or disconnection in some cases are conceivable.

In such a case, it is not possible to control the intake air amount accurately and responsively during idling, so depending on the valve opening at the time of failure, rough idling (
This will result in engine malfunctions such as an increase in the rotation speed (in the case of a valve-opening variable car) or an increase in the rotation speed (in the case of a valve-opening variable car).

Therefore, there are two types of fail-safe measures in such cases: 1. Furthermore, as a means for compensating the control characteristics of the intake air amount control valve, as described in, for example, Japanese Patent Laid-Open No. 124038/1983, a device has been used in series with the intake air amount control valve for controlling the idle rotation speed. Install a flow regulating valve,
Some devices are designed to limit the intake air flow rate when the intake air amount control valve is malfunctioning as described above, especially when the malfunction causes an increase in rotation. Such a flow rate regulating valve is generally designed to change the valve opening depending on the engine cooling water temperature, taking into consideration cases such as when warming up and increasing the amount of water (see FIG. 6).

(Problems to be Solved by the Invention) However, when the above-described flow rate regulating valve configuration is adopted, the following problem occurs when the intake air amount control valve is normal.

That is, when the temperature of the engine cooling water is low, such as during a cold start of the engine, the opening degree of the flow rate regulating valve becomes large, as is clear from FIG. Pressure difference ΔP between upstream and downstream of the current-controlled TIE magnetic valve, which is the intake air amount adjustment means
(ΔP=P, -P, . . . see FIG. 2) is sufficiently large. Therefore, the intake air amount is controlled (
It is sufficient to perform duty ratio control).

However, on the other hand, when the warm-up of the engine progresses beyond a certain point and warm-up is almost completed, the temperature of the cooling water of the engine rises, so the opening degree of the flow rate regulating valve becomes smaller. As a result, the downstream pressure (P in Figure 2) of the current-controlled solenoid valve becomes close to positive pressure as negative pressure from the engine is less likely to act on it, and the pressure difference with the upstream pressure P1 (P+Pt =8P) becomes weaker. As a result, even if the current value applied to the current-controlled solenoid valve is increased based on the normal control characteristics, the target intake air increase ffi
No value will be obtained (see solid line in Figure 5). Therefore, with the configuration of the conventional idle speed control device described above, accurate and stable control of the idle speed cannot be performed.

(Means for Solving the Problems) The present invention was made for the purpose of solving the above problems, and in order to solve the problems, the throttle valve is bypassed in the middle of the intake passage of the engine. an intake air amount control valve that is electrically controlled to open and close at least during idle operation and that changes the amount of intake air based on preset control characteristics; and a flow rate regulating valve that regulates the amount of intake air controlled by the intake air amount control valve according to the temperature of the engine cooling water, in which the intake air amount control valve is arranged in series. A control characteristic variable means for varying the control characteristic is provided, and the intake air amount control characteristic of the intake air amount control valve is varied in accordance with the valve opening degree of the flow rate regulating valve.

(Function) According to the problem solving means of the present invention, an intake air amount control valve that controls the idle rotation speed by adjusting the intake air 1 during idle operation is provided in the bypass intake passage of the engine, By driving and controlling the intake air amount control valve according to the amount of rotational deviation between the actual engine speed and a predetermined target idle speed, the engine's intake air amount is varied and the actual idle of the engine is controlled. The rotational speed is controlled to converge to the target idle rotational speed.

Further, in the bypass intake passage, a flow rate regulation valve is arranged in series with the intake air amount control valve as in the past, and the valve opening degree of the flow rate regulation valve changes depending on the value of the engine cooling water temperature. It is made variable according to the amount of air required by the engine.

Focusing on the fact that the opening characteristic of the flow rate regulation valve itself is reliably inversely proportional to the engine cooling water temperature, the intake air amount control is adjusted according to the opening degree of the flow rate regulation valve. The duty ratio of the control signal of the intake air amount control valve is appropriately corrected. Therefore, desired intake air amount control characteristics can be ensured regardless of changes in the opening degree of the flow rate regulating valve.

(Example) First, FIGS. 2 to 4 show an idle speed control device for an automobile engine when the present invention is applied to the engine, and FIG. A schematic diagram of the system, FIG. 3 is a flowchart showing the idle speed control operation of the engine control unit in the control system, and FIG. 4 is a diagram of the operation characteristics.

First, the outline of the control system according to the embodiment of the present invention will be explained with reference to FIG. 2, and then the control operation of the main parts will be explained.

In FIG. 2, reference numeral 1 denotes the engine body, where intake air is taken in from the outside via an air cleaner 30, and then supplied to each cylinder via an air flow meter 2, a throttle chamber 3, etc. Further, fuel (gasoline) is supplied from a fuel tank (gasoline tank) 12 to the engine side by a fuel pump 13, and is injected into the intake boat of the engine body l by a fuel injector 5 in synchronization with the ignition timing. There is. The amount of air taken into the cylinder when the accelerator pedal is operated is controlled by a throttle valve 6 provided in the throttle chamber 3. The throttle valve 6 is operated in conjunction with the accelerator pedal, and is maintained at a minimum opening level in the idling state.

The throttle chamber 3 is provided with a bypass intake passage 7 that bypasses the throttle valve 6. First, the bypass intake passage 7 has an upstream side that performs feedback control of the engine speed with high accuracy during idling operation. A current-controlled solenoid valve (so-called IsC valve) 8 is provided as an intake air control means for controlling the intake air. Further, on the downstream side thereof, there is provided a flow rate regulating valve 22 that regulates the intake air flow rate controlled by the current-controlled solenoid valve 8 according to the temperature of the engine cooling water.

The flow rate regulating valve 22 is made of, for example, a wax valve,
A part of the engine cooling water passage 23 is connected thereto. Therefore, in the idling operating state, the intake air metered through the air flow meter 2 is supplied to the combustion chamber in each cylinder on the engine body side via the bypass intake passage 7, and the amount of intake air is as described above. It is adjusted by the opening degrees of the current-controlled solenoid valve 8 and the flow rate regulating valve 22. The current-controlled solenoid valve 8 has its opening/closing state r14 (valve opening) controlled according to the duty ratio of an intake air amount control signal Tl5C supplied from an engine control unit (hereinafter abbreviated as ECU) 9, which will be described later. (See the flowchart in FIG. 3...described later).

Further, the reference numeral 1O indicates, for example, an exhaust pipe that includes a three-way catalytic converter (catalyst converter) I1 in the middle of the exhaust passage and has an exhaust gas purifying function. In the upstream portion of the three-way catalytic converter 11 of the exhaust pipe 10,
0.0 for detecting the oxygen concentration (Δ/F) in exhaust gas.
A sensor 21 is provided.

On the other hand, reference numeral 14 denotes an ignition plug provided in the cylinder head of the engine body 1, and the ignition plug 14
A predetermined ignition voltage is applied to the EC via the distributor 17 and the igniter 18, and the application timing of this ignition voltage, that is, the ignition timing is determined by the above-mentioned EC.
It is controlled by the ignition timing control signal Igc supplied from U9 to the igniter I8. Furthermore, reference numeral 20 denotes a boost pressure sensor 20, which detects an engine boost pressure B corresponding to the engine load and inputs it to the ECU 9. Further, IG-9W is an ignition key switch for the engine and is turned ON when the engine is started, and its ON signal is input to the ECU 9 as an ECU trigger and an engine start state detection signal. Also, code 1
9 indicates a knock sensor. Further, reference numeral 24 is an intake air temperature sensor that detects the intake air temperature T I-I A, and 25 is a voltage sensor that detects the voltage VB of the battery BAT.

The ECU 9 is, for example, a microprocessor (CPU)
It consists of a memory (INOM and RAM) and an interface (Ilo) circuit. The interface circuit of this ECU 9 includes, for example, an engine starting state detection signal (ECU trigger) from the ignition key switch IC-5W, an engine rotation speed (and crank angle sensor) from the engine rotation speed sensor (and crank angle sensor) 15, ) detection signal NE(θ
NE), detection signal THW of the cooling water temperature of the engine body 1 detected by the water temperature thermistor 16, O! Oxygen concentration in exhaust gas (air-fuel ratio A/F) detection signal vO detected by sensor (oxygen sensor) 21, air flow meter 2
Intake air amount detection signal Q detected by intake air temperature detection signal Q vs. intake air temperature detection signal detected by intake temperature sensor T -1-I
Various detection signals such as A, ignition timing detection signal 1gc from the distributor 17, and battery voltage Va are inputted. Then, the ECU 9 determines that the actual air-fuel ratio A/F of the engine, which is indicated by the detection value ■0 of the 02 sensor 21, is the stoichiometric air-fuel ratio (14
, 7) in the exhaust gas based on the oxygen concentration detection signal ■0 of the sensor 21 installed in the exhaust system of the engine so as to converge within a predetermined target air-fuel ratio range (window) centered on from the fuel injector 5, which is set based on the intake air amount Q measured by the air flow meter 2, according to the determined value. The basic fuel supply 'ff1Tp of the engine is configured to perform feedback correction control with high accuracy. On the other hand, when the operating state of the engine is in a predetermined high load/high rotation range, for example, the feedback correction control is stopped and oven loop control is performed to an air fuel ratio richer than the stoichiometric air fuel ratio. .

On the other hand, the above engine has an ignition key switch IC.
;-When the starting state is 5W-ON, the intake air ff is adjusted according to the engine cooling water fj and T HW values at that time.
1Q is increased, and the fuel supply m is fixedly increased and controlled by the oven loop accordingly (amount increase correction at startup)
. That is, when the engine cooling water temperature value THW is low, the temperature of the fuel adhering portion is also low and the vaporization of the fuel is poor.

Therefore, with only the basic fuel injection amount based on the intake air amount, the air-fuel ratio A/F that can actually contribute to engine combustion will be considerably lower than the target air-fuel ratio. As a result, if no increase correction is performed, even if the engine is started, engine malfunctions such as unstable idle rotation, surging, and engine stalling will occur. Therefore, the fuel increase correction value at the time of engine startup is fixedly determined according to only the cooling water temperature value THW as described above, and the lower the cooling water temperature THW, the more the fuel increase correction value (engine completion (initial value until reaching the explosion) cswo increases. Therefore, the opening degree of the flow rate regulating valve 22 is also maintained at the maximum opening degree in the case of cold deafness (see FIG. 6).

The fuel whose amount has been increased in this manner is injected into the intake boat of the engine from the 72-L injector 5 of each cylinder in synchronization with the ignition timing indicated by the ignition timing control signal Igc according to the cranking rotation of the engine. be done. Then, the injection m is tailed (accurately corrected) as described later in accordance with the engine's repeated explosions as the starting state of the engine progresses.

Next, the engine control unit (ECU) 9
The control operation of the idling speed (intake air amount) including the time of starting the engine will be explained in detail with reference to the flowchart of FIG. 3 and the operating characteristic diagram of FIG. 4.

First, in step S, the engine cooling water temperature fa T
1-(Continue W. Then proceed to step S,
Basic intake air fXI G B, engine cooling water temperature correction coefficient G ow, initial increase correction coefficient at startup (based on water temperature) GS
Calculate each WO. Further, in step S3, the temperature THA of the intake air is read. Then, the process further proceeds to step S, in which an intake temperature correction coefficient GH^ and an initial increase correction coefficient at startup (intake temperature reference) GSAO corresponding to the above-mentioned intake temperature T II A are calculated.

Next, in step S, the voltage VB of battery B is further read, and in step S6, the corresponding voltage correction coefficient CBA is calculated.
Calculate T.

Then, in the following step S, it is determined whether the current engine operating state is starting (in short, cranking or not), and if YES (starting), the next step S is performed. The value of the start-up increase correction coefficient Gsv based on the above engine coolant iW T HW is the initial start-up increase value (
Water temperature)
After each setting is made to SAO, the process proceeds to the next step Sho, which determines whether the engine external load is ON or OFF.If the answer is No, which is not during starting, the process moves to the other step S, and the process is performed according to the above-mentioned water temperature and intake air temperature. The initially set starting increase m value Gsw and the value Gs^ are each tailed (reduction correction) by predetermined step values A and B up to a predetermined guard value. Then, the next load determination step S1G
Then, it is determined whether or not the external load of the engine is ON, such as the air conditioner switch ON or the power steering switch ON, and if YES (external load ON), the process advances to the next step S11 and the engine is turned on. After calculating the load correction QGL corresponding to a certain load amount (total amount), the process proceeds to the idle determination operation in step S (s).

On the other hand, in the case of No to turn off the load, the process moves to step Si1, calculates the value of the load correction mGL as 0 value, and moves to the next step S13.

In step S+3, it is further determined whether the current engine operating state is an idle operating state (idle contact ON), and if YES (idle), first step S0
After calculating and setting the idle target rotation speed No in step S13 and reading the actual engine rotation speed NH in step S13, proceed to step S.

Step 8 proceeds to calculate the feedback correction coefficient CF+3 for the intake air amount corresponding to those rotational deviations (No-Ni:), while in the case of the non-idling state (No), the feedback correction coefficient GFB for the idle rotation speed control is calculated. value 0
Step S after setting the calculation to the value.

Proceed to. When the calculation of the feedback correction coefficient GFB according to the rotational difference is completed in the above step S16, it is determined in step S16 whether the learning condition is satisfied, and if YES that the learning condition is satisfied, the learning value GLflN is first calculated. At the same time, after attenuating the correction coefficient GFB by reflecting the calculated value, step S.

Proceed to.

In step StO, the various intake temperature correction coefficients Gsw, GSA, GLSG are applied to the basic control fiiGB based on the water temperature calculated in step S above.
The final intake air amount control amount (electromagnetic valve control amount) GA value (duty ratio) is calculated by adding FBNGLAN to each value.

And then the next step S! 1, the final control amount G^ is multiplied by the intake air temperature correction coefficient Go^ to calculate the total intake air filling ff1Q^. After the calculation of Q^ is completed, step s! Proceed to step t and fill the above intake air m
Q^ and engine cooling water temperature mTI (W) are parameters (
A basic duty value Tl5CO of a solenoid valve control signal for driving the current-controlled solenoid valve 8 is calculated as a variable (variable).

Next, the process proceeds to step StS, where the basic fIiTIscO of the solenoid valve control signal is combined with a voltage correction coefficient CBAT that takes into account fluctuations in the voltage VB of the battery B and a positive coefficient CTHW of the water temperature h.
By multiplying by The current-controlled solenoid valve 8 is driven.

As a result, according to the configuration of the above embodiment, due to the presence of the above-mentioned flow rate regulating valve 22, as indicated by diagonal lines in FIG. 4, the solenoid valve control signal is If only the current value of Tl5C is increased, the original linear characteristic (broken line C in Figure 5) cannot be obtained, and even in the region where the intake air amount is insufficient (region in Figure 5 (b)), the flow rate regulating pulp 22 itself will not open. The valve characteristic is originally the engine cooling water temperature THW.
Focusing on the fact that it is definitely inversely proportional to , the duty ratio of the solenoid valve control signal Tl5C for controlling the amount of intake air is appropriately increased and corrected according to the opening degree of the flow rate regulating valve 22. ing. Therefore, the desired intake air amount control characteristic (characteristic substantially corresponding to the characteristic shown by the solid line in FIG. 4 described above) can be ensured regardless of the change in the opening degree of the flow rate regulating valve 22.

In other words, as mentioned above, when the engine cooling water temperature TI-IW is low, such as when the engine is cold started, the valve opening of the flow rate regulating valve 22 is normally large.
Therefore, the pressure difference Δ between the upstream and downstream sides of the current-controlled solenoid valve 8
P (ΔP = P IP t) is sufficiently large as shown in Figure 5 (
It is sufficient to control the intake air amount using the characteristics of the linear section in a), but if the warm-up of the engine has progressed beyond the point where warm-up is almost completed, the engine cooling water temperature TH
Since W increases, the opening degree of the flow rate regulating valve 22 becomes smaller. As a result, the downstream pressure P of the current-controlled solenoid valve 8 becomes close to positive pressure as the negative pressure from the engine is less likely to act on it, and the pressure difference P, -P with the upstream pressure P.
, =ΔP becomes smaller. As a result, even if the current value applied to the current-controlled solenoid valve 8 is increased based on normal control characteristics, the target intake increase value cannot be obtained. Therefore, in this case, accurate and stable control of the idle speed cannot be performed with the configuration as it is.
・However, as mentioned above, the current control type solenoid valve 8
When the current value Tl5C applied to the engine cooling water temperature Tl5C is increased by the corresponding amount in anticipation of the engine cooling water temperature Tl5C as shown in step S above, the decrease in the intake air amount due to the closing of the flow rate regulating valve 22 is corrected. can be appropriately offset by increasing the opening of the current-controlled solenoid valve 8, and the idle rotation speed can be controlled with substantially linear characteristics as in the case where the flow rate regulating valve 22 is not provided. You will be able to do this.

(Effects of the Invention) As explained above, the present invention includes a bypass intake passage formed by bypassing a throttle valve in the middle of the intake passage of an engine, and electrically connects the bypass intake passage to the bypass intake passage at least during idling operation. an intake air amount control valve that controls opening and closing of the valve and changes the amount of intake air based on preset control characteristics; In an engine in which a flow rate regulating valve for regulating a flow rate is disposed in series with each other, a control characteristic variable means for varying the control characteristic of the intake air amount control valve is provided to control the intake air amount of the intake air amount control valve. The present invention is characterized in that the characteristics are made to vary depending on the opening degree of the flow rate regulating valve.

That is, according to the configuration of the present invention, an intake air amount control valve is provided in the bypass intake passage of the engine to control the idle rotation speed by adjusting the amount of intake air during idling operation, and the intake air amount is adjusted. By driving and controlling the control valve according to the amount of rotational deviation between the actual engine speed and a predetermined target idle speed, the amount of intake air of the engine is varied, and the actual engine idle speed is adjusted to the above level. Control is performed to converge to the target idle rotation speed.

Also, in the bypass intake passage, as in the past, J:,
A flow rate regulating valve is disposed in series with the intake air amount control valve, and the valve opening degree of the flow rate regulating valve is made variable in accordance with the amount of air required by the engine, which changes depending on the value of the engine cooling water temperature. .

Focusing on the fact that the opening characteristic of the flow rate regulation valve itself is reliably inversely proportional to the engine cooling water temperature, the intake air amount control is adjusted according to the opening degree of the flow rate regulation valve. The duty ratio of the control signal of the intake air amount control valve is appropriately corrected. Therefore, desired intake air amount control characteristics can be ensured regardless of changes in the opening degree of the flow rate regulating valve.

Therefore, according to the configuration of the present invention, when the intake air pressure difference between the upstream side and the downstream side of the intake air amount control valve changes due to a change in the opening degree of the flow rate regulation valve, the intake air amount control valve changes accordingly. The opening degree is appropriately corrected with good responsiveness to the predetermined opening degree increasing side or decreasing side compared to the original opening degree.

As a result, it becomes possible to always achieve the desired intake air m control characteristics regardless of changes in the opening degree of the flow rate regulating valve, and it becomes possible to realize an accurate and stable idle speed control function. .

[Brief explanation of the drawing]

Fig. 1 is a diagram corresponding to the claims of the present invention, Fig. 2 is a control system diagram of an engine idle speed control device according to an embodiment of the present invention, and Fig. 3 is a diagram showing the control operation of the device according to the embodiment. FIG. 4 is a control characteristic diagram showing the effects of the device according to the embodiment in comparison with that of a conventional example, and FIG. Figure 6 is a graph showing the general relationship between the solenoid valve control current value and the intake air flow rate supplied to the engine. It is a general valve opening characteristic diagram. 1... Engine body 2... Air flow meter 4... Idle contact 5... Fuel injector 6... Throttle valve 7... Bypass intake passage 8 ...Current control type solenoid valve 15 ...Engine speed sensor 22 ...Flow rate regulation valve 23 ...Engine cooling water passage

Claims (1)

[Claims] 1. A bypass intake passage is formed in the middle of the intake passage of the engine by bypassing the throttle valve, and the bypass intake passage is electrically controlled to open and close at least during idle operation, and the amount of intake air is controlled in advance. An intake air amount control valve that changes the intake air amount based on the characteristics and a flow rate regulation valve that regulates the amount of intake air controlled by the intake air amount control valve in accordance with the temperature of the engine cooling water are arranged in series with each other. In the engine, a control characteristic variable means is provided to vary the control characteristic of the intake air amount control valve, and the intake air amount control characteristic of the intake air amount control valve is varied in accordance with the valve opening degree of the flow rate regulating valve. An engine idle speed control device characterized by: