JPS6128733A - Method of controlling number of idle revolutions of engine - Google Patents

Abstract

PURPOSE:To prevent sudden decreases in the number of revolutions of an engine and stop of an engine, by a method wherein the one of an amount of air sucked and the fuel injecting time of a fuel injection valve is maintained at a specified value, and the other is varied according to the set number of idle revolutions. CONSTITUTION:In a step 201, an amount Q of air sucked and a signal N for the number of revolutions of an engine are inputted. In a step 204, an intake air amount supplied to an engine after bypassing a throttle valve is calculated. In a step 206, an injecting time tau of an injector is controlled. Through repetition of the aboves, an intake air amount is converged to a set indle intake air amount, and the number of revolutions of an engine is converged to the set number of idle revolutions. This causes the number of idle revolutions of an engine to be kept at a specified value, resulting in the possibility to prevent stop of an engine.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for controlling the idle speed of an engine.

[Conventional technology]

In recent years, engines have been made lighter and have lower friction, and the amount of intake air during idling has tended to decrease. At the same time, efforts have been made to lower the idling speed in order to improve fuel efficiency. However, when the engine is started or a load from a power steering pump or the like is applied in such a state, there is a problem in that the rotational speed suddenly drops suddenly, eventually leading to the engine stalling.

The main cause of this phenomenon is the absolute insufficient amount of intake air during idling operation. As a countermeasure, measures are used such as detecting the load effect and increasing the amount of intake air that bypasses the throttle valve using a valve using an electromagnetic solenoid, but there is a delay in response before it is reflected in combustion, and the engine stalls. We have not yet reached the point where it has been resolved.

[Problem that the invention seeks to solve]

The problem to be solved by the present invention is the sudden drop in engine speed due to the effect of load on the engine, and the risk of engine stalling due to this.The purpose of the present invention is to solve the above problem. The object of the present invention is to provide an engine idle speed control method that is strong against load effects on the engine.

[Means to solve the problem]

In order to solve the above problem, in the present invention, the amount of intake air that is fed into the engine by bypassing the throttle valve in the intake pipe and the fuel injection time of the fuel injection valve that supplies fuel to the engine are adjusted. By keeping one constant and changing the other according to the set idle speed,
The idle speed of the engine is controlled to be kept at a predetermined constant value.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram of an engine to which the present invention is applied. An intake pipe 2 that feeds intake air into an engine 1 has an air cleaner 3, an air flow meter 4, a throttle valve 5, an air cleaner 3, an air flow meter 4, a throttle valve 5, and an intake manifold 6, and a fuel injection valve 7 (hereinafter referred to as an "injector") is provided at the most downstream portion of the intake pipe 2, immediately before the engine 1.

Also, a bypass passage 8 is provided so as to bypass the throttle valve 5.
is provided from the upstream side of the throttle valve 5 of the intake pipe 2 to the intake manifold 5, and this bypass passage 8
An idle air amount control valve 9 (hereinafter referred to as rlAcVJ) that controls the amount of intake air sent to the engine 1 via the bypass passage 8 is provided in the middle of the engine.

The throttle valve 5 is provided with an idle switch 5a that detects the fully closed state of the throttle valve 5 and turns it on at that time, and a signal from the idle switch 5a is input to the computer 10. The computer 10 also receives an intake air amount signal from the F-flow meter 4, an engine rotation speed signal from a distributor 11 provided in the engine 1, and a water temperature signal from a water temperature sensor 12 that detects the cooling water temperature of the engine 1. These signals are used to output signals to the IACV 9 and the injector 7 to drive them in accordance with the state of the engine 1.

Next, the process executed by the computer 10? A method for controlling the idle rotation speed of the engine 1 will be explained using the flowchart shown in FIG.

First, in step 201, the intake air amount Q from the air flow meter 4 and the current engine speed signal N from the distributor 11 are taken in. Next, in step 202, it is determined whether the throttle valve 5 is fully closed, that is, whether the idle switch 5a is in the on state, and it is determined whether the engine 1 is in the idle operating state. If it is determined that the engine is in an idling state, the process proceeds to step 203, where it is determined whether the cooling water temperature U of the engine 1 is higher than a predetermined water temperature value uO. In other words, it is determined whether or not the engine 1 is in a predetermined warm-up state, and it is determined that the cooling water temperature U is higher than the predetermined water temperature value uo, that is, the engine 1 is in a predetermined warm-up state. If so, proceed to step 204. In step 204, the bypass intake air amount A passing through the bypass passage 8 is calculated. Step 2
Bypass intake air amount is increased or decreased in inverse proportion to the difference (Q - Q o ) between the intake air amount Q taken in at 01 and the set idle intake air amount Qo. Note that a□ in the formula is a proportionality constant, and ao<O. Also, bypass intake air amount A
The value Am detected from the map is used as the first value of .

Then, in step 205, an output is output to the IACV 9 to open the opening according to the bypass intake air amount A just calculated. Next, proceeding to step 206, the current engine rotation speed N and the set idle rotation speed N acquired in step 201 are obtained.

The injection time τ of the injector is increased or decreased in inverse proportion to the difference (N No). Note that to in the formula is a proportionality constant, and to is <0. Also, the value τm detected from the map is used as the first value of the injection time τ. Then, in step 210, the injector 7 is
Outputs to open the valve. Thereby, the injector 7 supplies a predetermined amount of fuel to the engine 1 through normal synchronous injection. After the output of the injection time τ to the injector 7 is completed in step 207, the process returns to step 201 and repeats the above-mentioned routine, and through this repetition, the intake air amount Q is set to the idle intake air by the bypass air amount control by the IACV9. At the same time, the current engine speed N converges to the set idle speed NO due to the injection time τ of the injector, and the desired idle-like engine operation is maintained.

Note that if it is determined in step 202 that the idle switch 5a is off, that is, the throttle valve 5 is not in the fully closed state, the process proceeds to step 208, where Q/ is determined from the intake air amount Q and the current engine speed N. Normal operation is performed with the current injection time τ of the injector 7 proportional to H.

(Stoichiometric air-fuel ratio control) Also, in step 202 it is determined that the idle switch 5a is on, and in step 203
Even if the engine 1 cooling water temperature U reaches the predetermined water temperature value u(
If it is determined that it is lower than 1, the process proceeds to step 209, where the bypass intake air amount A is set to a value A (u) according to the cooling water temperature U determined in advance by the map, and the bypass intake air amount A is set to a value A (u) according to the cooling water temperature U determined in advance by the map. output to the IACV 9 to open the opening, and proceed to step 208, supply fuel from the injector 7 to the engine 1 with an injection time τ proportional to Q/N, and warm up the engine 1 until the engine 1 is warmed up. Drive. Note that Ko in the equation of step 208 is a coefficient (constant), and K+(u) is a coefficient whose value changes depending on the water temperature.

Here, the above-mentioned set idle intake air amount Qo and set idle rotation speed No will be described. For example, A/F=14.
When idling at a stoichiometric air-fuel ratio of 5, there is an idle intake air amount Q at which the engine 1 rotates at a rotational speed N1. Here, if this idle intake air amount Q is maintained and the air-fuel ratio is made lean, the idle rotation speed N+ decreases to a certain rotation speed N2 (N2<Nl). Therefore, the above-mentioned idle intake air amount Q may be set as the set idle intake air amount QO, and the idle speed N2 that is low enough to maintain the rotation of the engine 1 may be set as the set idle speed N.

In the end, it is possible to set the idle intake air amount to a large amount, make the air-fuel ratio at that time lean, and keep the idle rotation speed low (suppressed). By pre-setting the amount of intake air to be large, it is possible to reduce the load generated during idling operation.
A sufficient amount of idle intake air is ensured, making it possible to control the idle speed of the engine, which is resistant to loads.

Note that, as described above, the lean air-fuel ratio during idling operation naturally falls within the possible air-fuel ratio range, and although the rotation of the engine 1 does not stop due to misfire, rotational fluctuations tend to increase. However, countermeasures can be taken by improving the ignition system and the swirl control pulp installed near the intake port, such as improving ignition performance by using a platinum plug with a large gap length in the ignition system.

Next, another embodiment of the present invention will be described with reference to FIG.

FIG. 3 shows an engine 1 having the same configuration as shown in FIG.
Steps 301 to 303 and steps 308 and 309 are similar to those in the previous embodiment, and in steps 304 to 307, the bypass intake air amount A is applied to the current engine in step 301. Difference between rotation speed N and set idle rotation speed No. (N-
No), and IACV9 accordingly.
Then, the injection time τ of the injector is increased or decreased in inverse proportion to the difference between the current injection time τ and the set time τ0, and the fuel from the injector 7 to the engine 1 is increased or decreased accordingly. The amount is increased or decreased. When this routine is repeated, the injection time τ becomes the set time τ0, and the idle speed N becomes the set idle speed N due to the bypass intake air amount A.

converges to maintain the desired idle state of operation.

In addition, low (suppressed set idle rotation speed N).

When the idle speed is maintained at , the air-fuel ratio is controlled to be lean for the fuel amount determined by the injector set time τ0, and the bypass intake air amount A is set to the set idle speed No. that is kept low. This is determined by time τ0.

Further, aOr tO in FIG. 3 is a proportionality constant of a negative value, similar to the embodiment shown in FIG. Further step 3
04. At '306, the first values of the bypass intake air amount A and the injection time τ are obtained in the same manner as in the previous embodiment.

Therefore, in this embodiment, the predetermined injection time (set time τ0)
The amount of fuel determined by As in the above-described embodiment, the idle intake air amount is set to be relatively large, making it possible to control the idle rotation speed of the engine that is resistant to loads.

Next, still another embodiment of the present invention will be described using FIG. 4.

FIG. 4 is a flowchart showing this embodiment, but this embodiment differs from the above-mentioned embodiments in that the IA in FIG.
This is commonly used in engines that do not have a CV9 and the amount of bypass intake air is manually set using an idle adjustment screw.

First, in step 401, the intake air amount Q and the current engine speed N are taken in, as in the previous embodiment, and in step 402, it is determined whether the idle switch 5a is on. If the idle switch 5a is on, the process proceeds to step 403, where it is determined whether the coolant temperature U of the engine 1 is higher than the set water temperature value un, and if it is higher, the process proceeds to step 40.
Proceed to step 4. In step 404, the injection time τ of the injector is increased or decreased in inverse proportion to the difference between the current engine speed N taken in in step 401 and the set idle speed No. Note that to in the formula is a negative proportionality constant as in the above embodiment. Further, as the first value of the injection time, the value τm detected from the map is used as in the above embodiment.

Then, in step 405, an output is issued to open the injector 7 for the injection time τ just calculated, whereby a predetermined amount of fuel is supplied from the injector 7 to the engine 1. After this, the process returns to step 401 and by repeating this routine, the idle speed converges to the set idle speed No., and the desired idle state operation is maintained.

Further, when it is determined in step 402 that the idle switch 5a is off, in step 406, the injection time τ of the injector 7 is determined by a common calculation method, and is outputted, and the injection time τ is determined in step 406. Return to 402. Furthermore, if it is determined in step 403 that the cooling water temperature U is lower than the set water temperature value uQ, the process proceeds to step 407, where the amount of intake air is increased by a mechanism such as an air valve according to the value of the cooling water temperature U, and the process proceeds to step 406. In response to this increased amount of intake air, the injection time τ of the injector increases, the amount of fuel supplied to the engine 1 increases, and idle up is performed.

If the opening degree of the adjustment screw is set to flow enough intake air to withstand the load, the idle speed will be equal to the set idle speed NO.
If the injection time τ of the injector converges to a predetermined time and the set idle speed No. at this time is set low, the air-fuel ratio at that time will settle to a lean state. .

Accordingly, in this embodiment as well, the amount of intake air during idling can be set to a relatively large amount, and the injection time of the injector is determined so that a predetermined idling speed is achieved for the set amount of intake air. Even when a load occurs, a sufficient amount of intake air is ensured and control that is strong against the load can be obtained.

Note that the first value of the injection time τ in FIG. 4 is obtained in the same manner as in the previous embodiment.

〔Effect of the invention〕

As described above, in the present invention, either the intake air amount of the intake air that bypasses the throttle valve in the intake pipe and is sent into the engine, or the fuel injection time of the fuel injection valve that supplies fuel to the engine is determined. is maintained constant and the other is changed according to the set idle speed to maintain the engine idle speed at a predetermined constant value, so it is necessary to set the intake air amount to a large amount in advance. This makes it possible to prevent idling problems and engine stalling due to an absolute insufficient amount of intake air, and since the engine is controlled to a lean state, it has the excellent effect of reducing fuel consumption.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an engine in which an embodiment of the present invention is adopted, FIG. 2 is a flowchart showing a control method of an embodiment of the present invention, and FIG. 3 is a diagram showing another embodiment of the present invention. Flowchart showing an example control method. FIG. 4 is a flowchart showing still another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Engine, 2... Intake pipe, 4... Air flow meter, 5... Throttle valve, 5a... Idle switch, 7... Injector (fuel injection valve), 8...
- Bypass passage, 9...IACV (idle air volume control pulp), 10...computer.

Claims (1)

[Claims] 1. When the engine is in a predetermined warm-up state, the amount of intake air that bypasses the throttle valve in the intake pipe and is sent to the engine, and the amount of intake air that is supplied to the engine by bypassing the throttle valve in the intake pipe, and the amount of intake air from the fuel injection valve that supplies fuel to the engine. Maintain either the fuel injection time or the fuel injection time constant,
1. A method for controlling an engine idle speed, the method comprising controlling the idle speed of the engine so as to maintain the engine idle speed at a predetermined constant value by changing the other speed according to a set idle speed. 2. The engine idle speed control method according to claim 1, wherein the intake air amount of the intake air is changed by an idle air amount control valve.