JPS644061B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an engine intake air amount control device that performs feedback control of the idle speed to a target value.

(Prior Art) Recently, in many automobile engines, feedback control is performed to converge the idle rotation speed to a target value set in consideration of the warm-up state and the like. For this reason, as shown in Japanese Patent Application Laid-Open No. 55-60636, for example, an intake air amount adjusting means such as a proportional solenoid valve is provided in the bypass air passage that bypasses the throttle valve, so that during idling operation,
The amount of intake air flowing through the bypass air passage is adjusted depending on the difference between the current engine speed and the target engine speed. And, JP-A-54-
As shown in Publication No. 72319, the above feedback control is performed when at least two conditions are met: the engine speed is below a predetermined value, and the throttle valve opening is below a predetermined value. There is one that determines that the vehicle is being driven.

Incidentally, when starting an engine, it is common practice to increase the amount of intake air in order to make starting easier. However, in the case of this kind of engine, if the two conditions mentioned above are used to determine whether or not it is idling, the engine speed will change to the idling speed due to the increase in intake air at the time of starting. In some cases, the engine speed may not drop below a predetermined value, which is one of the conditions for determining that It was happening.

(Object of the Invention) The present invention has been made in consideration of the above circumstances, and provides an engine intake air amount control device that prevents the engine speed from remaining high even immediately after the engine is started. The purpose is to provide

(Structure of the Invention) In order to achieve the above-mentioned object, in the present invention, immediately after starting the engine, it is necessary to determine whether or not the engine is in idle operation, which is a precondition for starting feedback control. , the condition that the engine speed is less than or equal to a predetermined value is excluded.

Specifically, as shown in Figure 1, as in the past,
For example, an intake air amount adjusting means such as a proportional solenoid valve equipped with a bypass air passage that bypasses the throttle valve, and an intake air amount adjusting means such as a proportional solenoid valve that has a bypass air passage that bypasses the throttle valve, and at least when the engine speed is below a predetermined value and the opening degree of the throttle valve is below a predetermined value, the engine is idle. The engine includes idle determining means for determining that the engine is in operation, and feedback intake air control means for performing feedback control on the intake air amount adjusting means so that the engine speed converges to a target value during idle operation. and a startup intake air control means for controlling the intake air amount adjusting means to supply a predetermined amount of intake air when starting the engine;
Immediately after the engine is started, idle determination correction means is provided to exclude the condition that the engine speed is below a predetermined value in determining whether or not the engine is in idle operation.

(Example) In Fig. 2, 1 is the engine body, and the intake air is supplied by an air cleaner 2, an air flow chamber 3,
It is supplied to the combustion chamber 9 via the throttle valve body 4, the surge tank 5, the intake manifold 6, and the intake port 8 which is opened and closed by the intake valve 7. It consists of The amount of intake air flowing through this intake passage 10 is controlled by a throttle valve 11 and measured by an air flow meter 12.
The fuel injected from No. 3 is mixed. Further, exhaust gas from the combustion chamber 9 is discharged to the atmosphere through an exhaust port 15 opened and closed by an exhaust valve 14, an exhaust manifold 16, and the like.

A bypass air passage 17 is attached to the intake passage 10, which has an upstream end 1
7a is on the upstream side of the throttle valve 11,
Further, the downstream end 17b is the throttle valve 11.
are connected to the intake passage 10 on the downstream side thereof. And this bypass air passage 17
A solenoid valve 18, which is a proportional solenoid valve, is connected to the intake air amount adjusting means.

Reference numeral 19 in FIG. 2 is a control unit consisting of a microcomputer, and the control unit 19 receives the cooling water temperature as the engine temperature from the water temperature sensor 20, the engine speed from the rotation speed sensor 21, and the engine speed from the idle switch 22. ON whether or not the throttle valve 11 of is below a predetermined opening degree (in the embodiment, whether it is fully closed or not);
While the OFF signal and the amount of intake air from the air flow meter 12 are inputted, the control unit 19 outputs them to the fuel injection valve 13 and the solenoid valve 18. In addition, 23 in FIG. 2 is a starter motor, and the starter motor 23 is a starter switch (starter contact) of a key switch 24 operated by the driver.
It is connected to the battery 25 via 24a.

Next, the details of control by the control unit 19 will be explained based on the flowchart shown in FIG. 3, but explanations of parts not directly related to the present invention, such as fuel injection, will be omitted. In this embodiment, the period during which the engine speed is excluded from the idle determination condition immediately after the engine is started is mainly the period from when the engine is completely detonated until a predetermined time _T1 has elapsed. In addition, in this embodiment, during non-idling operation, the intake air amount is oven-controlled so that the amount of intake air is increased by a certain amount relative to the intake air amount corresponding to the target rotation speed by feedback control. , regardless of whether the feedback control is stable (converged to the target rotation speed), the above-mentioned increase in the fixed amount of intake air is added to the intake air amount corresponding to the target rotation speed. This includes control details. Further, the amount of intake air is adjusted by adjusting the opening degree of the solenoid valve 18, and the opening degree of the solenoid valve 18 is adjusted according to the duty ratio of the pulse output from the control unit 19. (The larger the duty ratio, the larger the opening degree of the solenoid valve 18).

First, in step 26, n ₁ is initialized to the above-mentioned time T ₁ , and n ₂ , which will be described later, is set to 0, and the integral duty ratio D _I becomes the basic duty ratio _DT , and the basic duty ratio
D _T is set to a set value B (for example, equivalent to 1000 rpm).

Next, in step 27, the cooling water temperature, engine speed, and information from the idle switch 22 are determined.
An ON or OFF signal is input as data.

After that, in step 28, a target rotation speed N _T during idling operation is calculated based on the cooling water temperature, and in step 29, a basic duty ratio D _T corresponding to this target rotation speed N _T is calculated.
Move to step 30.

From step 30 onward, the control of the intake air amount is roughly divided into engine startup, immediately after engine startup, and immediately after engine startup, so these are classified below with reference to FIGS. 4 and 5. However, for the sake of explanation, the period immediately after the engine starts (the 5th
We will start by explaining the control contents in the figure area (after the elapse of ○).

Immediately after engine startup In this case, the process moves from step 30 to step 35 via steps 31, 32, and 33, which will be described later.
In this step 35, as one of the conditions for determining that the engine is idling, it is first determined whether or not the engine speed N is smaller than a predetermined value _N0 , and if N is smaller than _N0 , the process moves to step 36. do. In this step 36, as another condition for determining whether or not the engine is in idle operation, it is determined whether or not the idle switch 22 is turned on while the throttle valve 11 is in a fully closed state. And the idle switch 22
If it is ON, this means that all the conditions for determining that the engine is idling are satisfied, so feedback control, which will be described later, is performed. Further, when it is determined that the engine speed N is greater than the predetermined value _N0 or that the idle switch 22 is off in step 36, it is determined that the engine is not in idle operation, and open control is performed. .

The feedback control and open control will be further explained below.

-1 During feedback control First, in step 37, the integral duty ratio D _I is calculated. This integral duty ratio D _I corresponds to the previous integral duty ratio D _I plus the deviation between the target rotational speed N _T and the current rotational speed N. This is always the basic duty ratio D _T for the solenoid valve 18.
This is to correct the above-mentioned deviation with respect to this basic duty ratio _DT since it is designed to output .

Next, in step 38, it is determined whether the timer _n2 is 0 or not, but since _n2 =0 has been initialized, the process first moves to step 39.

In step 39 above, the integral duty ratio
The basic duty ratio D _T is subtracted from D _I , and
A duty ratio D _TFB is calculated for use in open control, which will be described later. Then, in step 40, the integral duty ratio _DI is set as the final duty ratio _DW , and this final duty ratio _DW is outputted in step 41.
In other words, the target rotation speed N _T and the current rotation speed N
When the rotation speed N is larger than the target rotation speed N _T , a pulse with a duty ratio that compensates for the deviation between the
7, and conversely, when the rotation speed N is smaller than the target rotation speed N _T , the opening degree of the solenoid valve 18 is increased to increase the amount of intake air flowing through the bypass air passage 17 In this way, the engine rotation speed N is converged to the target rotation speed N _T.

Note that if n ₂ =0 is not determined in step 38, the timer is counted down in step 42, but this step 42 will be described later.

-2 During open control First, in step 43, it is determined whether or not n ₂ = 0. If n ₂ = 0, the process moves to step 44, and the intake air amount corresponding to the additional intake air amount during open control is determined. duty ratio
D ₀ is set. In addition, this additional amount D ₀ is
It is always assumed to be a constant value.

Next, in step 45, the above-mentioned additional duty ratio _D0 is added to D _TFB calculated in step 39 to calculate the corrected duty ratio _DM , and then in step 46, the above-mentioned corrected duty ratio D0 is added. D _M
A duty ratio D _I is calculated by adding the basic duty ratio D _T to the basic duty ratio D T .

After that, in step 47, the duty ratio D _I is set as the final duty ratio Dw, and then in step 41, a timer is set to n ₂ =T ₂ , and in step 41, the final duty ratio D _W is set to the solenoid valve 18. Output.

If it is determined in step 43 that n ₂ = not 0, the process moves to step 49,
Basic duty ratio D _T to corrected duty ratio D _M
The duty ratio D _I obtained by adding , that is, the duty ratio D _I obtained in step 46
However, in step 47, the final duty ratio is
It is said to be D _W.

Now, based on FIG. 4, further explanation will be given focusing on feedback control, open control, and switching between these times. In this Figure 4, region (1) represents a state in which feedback control is stable and converged to the target rotation speed N _T , and regions (2) and (6) represent a state in which feedback control is stable and transitions to open control. The state of
Region (3) represents a state in which feedback control is not yet stable, region (4) represents a state in which feedback control has transitioned from an unstable state to open control, and region (5)
shows the transition from open control to feedback control and then the feedback control becomes stable.
are shown respectively.

(b) When transitioning from open control to feedback control, set n ₂ in step 48 during open control.
= T ₂ , so until the relevant time T ₂ in which the feedback control becomes stable has elapsed,
This is the flow from step 38 to step 42 where timer n ₂ is counted down, and this time T ₂
After the process has passed, the flow moves from step 38 to step 39.

(b) When transitioning from a state where feedback control is stable to open control, the timer has finished counting in step 42, so n ₂ is set to 0 in step 43. The flow is from to 44. The duty ratio D _W output at this time is D _I +D ₀ , which is the sum of the duty ratio D _I for the deviation from the basic duty ratio D _T and the additional duty ratio D ₀ for open control. ,
45, 46). What this D _I + D ₀ means is that since D _I is the deviation from D _T , the overall duty ratio output to the solenoid valve 18 is the same as the basic duty ratio D _T. This is the sum of the duty ratio D ₀ added during open control.

From the next time onwards, the original step 43 will be used.
When processing from step 44 onward, step
Since n ₂ = T ₂ is set in step 48, the process moves from step 43 to step 49 and the duty ratio originally set in step 46 is set.
D _I is output as is as the final duty ratio D _W.

(c) When transitioning from a state in which feedback control is not stable to open control, the timer has not counted down completely in step 42, so _n2 in step 43 has not reached 0, and the process continues from step 43. This will lead to 49. At this time, the output duty ratio
D _W becomes the duty ratio D _M +D _T =D _I +D ₀ previously set in step 46.

In this way, in this embodiment, regardless of whether or not the feedback control stably converges to the target value, the duty ratio output during open control, that is, the amount of intake air flowing through the bypass air passage 17, is always , corresponds to the basic duty ratio D _T corresponding to the final target value of feedback control plus an additional amount D ₀ for open control.

When starting the engine (area ○a in Figure 5) In this case, the process moves from step 30 to step 50, where the final duty ratio D _W is set as
A duty ratio DS added by a predetermined amount at the time of starting to the basic duty ratio _DT (DS>D ₀ ) is set. After this final duty ratio D _W is set to D _I in step 51, it is output to the solenoid valve 18 in step 41, and an amount of intake air corresponding to the final duty ratio D _W is supplied. Note that whether or not it is time to start is determined based on the following conditions: the starter switch 24a is ON (of course, the key switch 24 is ON), and the engine rotation speed N is lower than the cranking rotation speed Ne by the starter motor 23. be done. Also, the reason why _DW is set to _DI in step 51 is because the integral duty ratio DI in step 37 was set during the feedback control described above _.
This is to provide an initial value for calculating .

Immediately after the engine is started (areas ○B and ○C in FIG. 5) When the engine is started with a complete explosion, the process moves from step 30 to step 31, where it is determined whether or not the timer _n1 is 0. Initially, n ₁ is initialized to be T ₁ , so the step
The timer moves to 52, and timer n ₁ starts counting down here. Thereafter, the process moves to step 36, where the same processing as described above is performed. In this case, immediately after starting the engine, even if the throttle valve 11 is fully closed, a situation may occur in which the engine speed N does not fall below the predetermined value _N0 .
35, i.e. engine speed N
The condition that N is less than or equal to a predetermined value N ₀ is excluded from the conditions for determining whether or not the vehicle is idling. Therefore, the idle switch 22 is turned on, that is, the throttle valve 11 is turned on.
As long as the engine is fully closed, the feedback control described above is performed regardless of the engine speed N, and the target engine speed is maintained.
It will converge to N _T.

In this embodiment, steps 32, 33, and 34 are performed in consideration of the case where the engine speed N does not decrease to the predetermined value _N0 even after the timer _n1 in step 52 has finished counting down. By providing _{each step of}
The process is configured to proceed to step 36 without passing through step 35. That is, if the engine speed N has not become equal to or lower than N _T +α in step 32, the process moves to step 34, where F (flag) is determined, but since this F has been initialized as 1, the to step 36, and skips step 35. And the engine speed N is
If it becomes smaller than N _T +α, the process moves from step 32 to step 33, where it is determined for the first time whether or not the engine speed N is equal to or less than a predetermined value N ₀ as a determining factor for the idling operating condition. After passing through step 35, even if the engine speed N becomes larger than N _T +α again, the route from step 34 to step 35 is continued. This is the engine speed N
When becomes N _T + α, the engine speed N
This is because even if there is some variation in the engine speed N, the engine speed N is maintained at a predetermined value _N0 or less, which is a prerequisite for performing feedback control. Note that normally, the time _T1 is set so that the engine speed N becomes equal to or less than the predetermined value _N0 after the elapse of the time _T1 , so steps 32, 33, and 34 described above are not necessarily necessary. be.

Although the embodiments have been described above, the present invention is not limited thereto, and includes, for example, the following cases.

The opening degree of the electromagnetic valve 18 may be adjusted by changing the cycle of pulses output thereto.

The intake air amount can be adjusted by adjusting the opening degree of the throttle valve 11 by using the throttle valve 11 also as an intake air amount adjusting means without providing a separate bypass air passage 17. Good too.

The control unit can be constructed by either an analog or digital computer.

(Effects of the Invention) As is clear from the above description, the present invention eliminates conditions related to engine speed immediately after starting the engine when determining whether or not the engine is idling. Therefore, even if the amount of intake air is increased when starting the engine, feedback control to converge the idle speed to the target speed is performed reliably, and the engine speed remains high. You can definitely avoid situations like this.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of the present invention. FIG. 2 is an overall system diagram showing one embodiment of the present invention. FIG. 3 is a flowchart showing an example of control contents of the present invention. Figure 4,
FIG. 5 is a diagram schematically showing an example of control contents of the present invention. DESCRIPTION OF SYMBOLS 1...Engine body, 17...Bypass air passage, 18...Solenoid valve, 19...Control unit, 21...Rotational speed sensor, 22...Idle switch.

Claims (1)

[Scope of Claims] 1. A rotation speed detection means for detecting the rotation speed of the engine; a throttle opening detection means for detecting the opening degree of a throttle valve; and an output of the rotation speed detection means and the throttle opening detection means. idling determination means for determining that idling operation is being performed when the engine rotational speed is at least a predetermined value or less and the opening degree of the throttle valve is at least a predetermined value or less; and an intake air amount adjusting means for adjusting the intake air amount of the engine. and feedback intake air control means that receives the output of the idle detection means and controls the intake air amount adjustment means during idle operation to control the engine rotation speed back to the target value, and the intake air control means when the engine starts. a starting intake air control means that controls the means to supply a predetermined amount of intake air suitable for starting; and a condition that the idle determining means is controlled immediately after the engine is started so that the engine speed is below a predetermined value. An intake air amount control device for an engine, comprising: idle determination correcting means for excluding the engine from determining whether or not the engine is idling.