JP2751330B2 - Idle speed control device for internal combustion engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an idle speed control device for an internal combustion engine, and more particularly to an idle speed control in a running state in addition to a stop state, and a control start timing during deceleration. Even if the engine speed is reduced during deceleration and feedback control is started, the second target idle speed during traveling set higher than the first target idle speed during stoppage can be obtained. (2) The rotation difference between the feedback control start rotation speed and the second target idle rotation speed can be reduced, and the target idle rotation speed can be controlled with a small control amount. The present invention relates to an idle speed control device for an internal combustion engine, which has good followability and can prevent a problem that engine stall occurs.

[Conventional technology]

In some internal combustion engines, an idle speed control device is provided to control the idle speed. The idle speed control device is provided with a bypass intake passage that bypasses the intake throttle valve of the internal combustion engine and communicates with the intake passage, a bypass intake amount control valve is provided in the bypass intake passage, and the bypass intake amount control valve is set to a duty value. To control the idle speed by feedback so that the engine speed becomes the target idle speed. As shown in FIGS. 9 and 10, the idle speed control device for the internal combustion engine performs idle speed control at a speed lower than the control start speed so that the engine speed reaches a target idle speed set in accordance with the coolant temperature. In addition, the idle speed control device includes the eleventh and twelfth
As shown in the figure, when all of the idle speed control start conditions of the intake throttle valve opening, the vehicle speed, and the engine speed of the internal combustion engine are satisfied, the engine speed is set to the target idle speed so that the engine speed becomes the target idle speed. Start control.

That is, when the idle switch is turned on, the intake throttle valve opening becomes the idle opening and the delay time elapses (idle switch ON + delay time), and when the vehicle speed detected by the vehicle speed sensor is lower than the control start vehicle speed (vehicle speed <control) Start engine speed) and the condition that the engine speed detected by the speed sensor is less than the control start speed (engine speed <control start speed), the engine speed becomes the target idle speed. The idle speed control is started as much as possible. Alternatively, when the idle switch is turned on, the intake throttle valve opening is set to the idle opening (idle switch O
N), the engine speed is lower than the target idle speed (engine speed <target idle speed), the condition that the vehicle speed detected by the vehicle speed sensor is lower than the control start vehicle speed (vehicle speed <control start vehicle speed), When both of the conditions that the engine speed detected by the speed sensor is less than the control start speed (engine speed <control start speed) are satisfied, the engine speed is set to the target idle speed so that the engine speed becomes the target idle speed. Start rotation speed control.

Further, when any one of the idle speed control start conditions is not satisfied, for example, when the idle speed control is stopped because the vehicle speed becomes equal to or higher than the control start vehicle speed, the duty value of the bypass intake air amount control valve is set to a fixed value. To maintain. The fixed value may be maintained at a preset constant value, or a duty value during idle speed control before stopping the idle speed control may be stored and maintained at the stored duty value. There is.

Such an idle speed control device is disclosed in
There is one disclosed in JP-A-63-215855. The technique disclosed in this publication prevents an increase in the idle speed in a no-load operation state when the bypass intake air amount shifts from a large amount to a small amount, and quickly stabilizes the idle speed to a predetermined idle speed.

[Problems to be solved by the invention]

By the way, as in the case of deceleration, when the idle switch is turned on, the intake throttle valve opening becomes the idle opening, the clutch is disengaged, the clutch switch is turned off, and the vehicle speed detected by the vehicle speed sensor is equal to or higher than the control start vehicle speed, As described above, the idle speed control is stopped, the duty value of the bypass intake air amount control valve is maintained at a fixed value, and the engine speed decreases toward the target idle speed.

However, at this time, if the bypass intake air amount of the bypass intake air amount control valve that is operated with the duty value being a fixed value is smaller than the required bypass intake air amount due to the load of the electric load or the load of the air conditioner or the like as an auxiliary device. When the engine speed drops, the engine speed may drop more than the target idle speed, causing engine stall. If the bypass intake air amount of the bypass intake air amount control valve that is operated with the duty value being a fixed value is larger than the required bypass intake air amount, the descending engine speed does not drop to the target idle speed, and conversely, May rise.

In this case, it is possible to additionally provide a load switch for detecting the contribution of the electric load or the like, and to start the idle speed control under the condition that the load is equal to or more than the control start load.
There is a disadvantage that the cost increases due to the addition of the load switch.

[Object of the invention]

Therefore, an object of the present invention is to stop the idle speed control when any one of the idle speed control start conditions is not satisfied, and then determine whether the intake throttle valve opening of the internal combustion engine is the idle opening and the vehicle speed. A condition that is equal to or higher than the control vehicle speed,
If any of the conditions that the engine speed is equal to or less than the second feedback control start speed set lower than the first feedback control start speed is satisfied, the control means sets the engine speed to the first target idle speed. By starting the feedback control of the idle speed as much as possible to reach the second target idle speed set higher than the idle speed, the idle speed control is performed not only in the stopped state but also in the running state, so that the control start timing at the time of deceleration can be advanced. Even if the engine speed is reduced during deceleration and feedback control is started, the second feedback control is performed based on the second target idle speed during traveling set higher than the first target idle speed during stoppage. The rotational difference between the start rotational speed and the second target idle rotational speed can be reduced, and the target idle rotational speed can be controlled with a small control amount. Come, then the good follow-up property of the control by the control width load can afford be varied greatly, in implementing an idle speed control system for an internal combustion engine capable of preventing the problem that generates engine stall.

[Means for Solving the Problems] In order to achieve this object, the present invention provides a condition that an intake throttle valve opening of an internal combustion engine is an idle opening, a condition that a vehicle speed is lower than a control vehicle speed, When both the condition that the engine speed is less than the first feedback control start speed and each of the idle speed control start conditions are satisfied, the intake throttle valve is bypassed so that the engine speed becomes the first target idle speed. In the idle speed control device for the internal combustion engine that starts controlling the bypass intake air amount, after stopping the idle speed control because any one of the idle speed control start conditions is not satisfied, an intake throttle valve of the internal combustion engine is provided. A condition that the opening is an idle opening, a condition that the vehicle speed is equal to or higher than the control vehicle speed, and a condition that the engine speed is lower than the first feedback control start speed. If both of the conditions that are equal to or less than the second feedback control start rotation speed are satisfied, the engine rotation speed is set to be higher than the first target idle rotation speed so as to reach the second target idle rotation speed. The present invention is characterized in that a control means for starting the feedback control is provided.

[Action]

According to the configuration of the present invention, after the idle speed control is stopped because any one of the idle speed control start conditions is not satisfied, the condition that the intake throttle valve opening of the internal combustion engine is the idle opening and the vehicle speed are If both the condition that the engine speed is equal to or higher than the control vehicle speed and the condition that the engine speed is equal to or lower than the second feedback control start speed set lower than the first feedback control start speed are satisfied, the control means causes the engine to operate. Feedback control of the idle speed is started so that the speed reaches the second target idle speed set higher than the first target idle speed. The control start timing can be advanced, and even if the engine speed decreases during deceleration and feedback control starts, the second target The rotation speed is set higher than the first target idle rotation speed at the time of stop, the rotation difference between the second feedback control start rotation speed and the second target idle rotation speed is reduced, and the target idle rotation speed is reduced with a small control amount. Even if the load subsequently fluctuates greatly, the controllability of the control is improved by a marginal control width, thereby preventing the problem of engine stall.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

 1 to 8 show an embodiment of the present invention.

In FIG. 1, 2 is an internal combustion engine, and 4 is an idle speed control device. The idle speed control device 4 bypasses the intake throttle valve 8 provided in the intake passage 6 of the internal combustion engine 2, and upstream and downstream of the intake throttle valve 8 and the downstream intake passage 6.
-2 bypass tank 12 for communication with surge tank 10
Is provided. The bypass intake passage 12 is provided with a bypass intake amount control valve 14 that is operated by a duty value. The bypass intake air amount that passes through the bypass intake passage 12 is adjusted by the bypass intake air amount control valve 14, and the idle rotational speed is controlled by feedback so that the engine rotational speed becomes the target idle rotational speed.

The bypass intake air amount control valve 14 is connected to a control unit 16 as control means. The control unit 16 includes a temperature sensor 18 for detecting the temperature of the cooling water of the internal combustion engine 2, a rotation speed sensor 20 for detecting the engine speed, and an on / off state when the intake throttle valve 8 is at the idle opening. An idle switch 22 that is turned off when the opening degree is exceeded or more, and a vehicle speed sensor 24 that detects a vehicle speed are connected. Thus, the idle speed control device 4 controls the idle speed at a speed lower than the control start speed so that the engine speed reaches the target idle speed set according to the coolant temperature.

The idle speed control device 4 includes an idle switch
The condition that the opening degree of the intake throttle valve 8 detected by 22 is the idling opening degree, the condition that the vehicle speed detected by the vehicle speed sensor 24 is lower than the control vehicle speed, and the engine speed detected by the speed sensor 20 are the first to be described later. When both the condition that the engine speed is less than the feedback control start speed and the idle speed control start condition are satisfied, the bypass intake air that bypasses the intake throttle valve 8 so that the engine speed becomes a first target idle speed that will be described later. Start controlling the volume.

As shown in FIG. 2, the control unit 16 has two first and second feedback control start rotation speeds NFB1 and NFB1 depending on the vehicle speed.
NFB2 and two first and second target idle speeds NE1 and NE2 are set.

More specifically, the first feedback control start rotation speed NFB1
Is used when the opening of the intake throttle valve 8 becomes the idle opening when the idle switch 22 is turned on and the vehicle speed detected by the vehicle speed sensor 20 becomes lower than the determination vehicle speed. The second feedback control start rotation speed NFB2 Is set to be lower than the first feedback control start rotation speed NFB1,
When the idle switch 22 is turned on, the opening of the intake throttle valve 8 becomes the idle opening, and is used when the vehicle speed becomes equal to or higher than the determination vehicle speed.

Further, as shown in FIG. 4, the first target idle speed NE
1 is a condition that the vehicle speed is lower than the determined vehicle speed (vehicle speed <determined vehicle speed), a condition that the engine speed Ne is equal to or lower than the first feedback control start speed NFB1 (Ne ≦ NFB1), The setting is used when both the condition that the opening of the throttle valve 8 becomes the idle opening (ID switch ON) is satisfied. The second target idle speed NE2
Are set higher than the first target idle speed NE1, the vehicle speed is equal to or higher than the determined vehicle speed (vehicle speed ≧ determined vehicle speed), and the condition that the engine speed Ne is equal to or lower than the second feedback control start speed NFB2. This setting is used when both (Ne ≦ NFB2) and the condition that the opening of the intake throttle valve 8 becomes the idle opening due to the turning on of the idle switch 22 (ID switch ON) are satisfied.

Then, the first and second feedback control start rotation speeds NF
B1 and NFB2 and the first and second target idle speeds NE1 and NE2 are set to have a magnitude relationship as shown in FIG.

The control unit 16 is configured to control the idle rotation speed control after stopping the idle rotation speed control due to the failure of any one of the idle rotation speed control conditions. If the engine speed Ne does not reach the lower one of the first and second feedback control start speeds NFB1 and NFB2 set and used according to each condition, as shown in FIG. Idle speed control duty value DTYA, DT set by
The idle speed control is performed using one of YB and DTYC.

At this time, the idle speed control duty value DTYA is
As shown in FIG. 6, the condition that the opening of the intake throttle valve 8 becomes the idle opening by turning on the idle switch 22 (ID switch ON), and the engine speed Ne is equal to or more than the first feedback control start speed NFB1. The condition is used when both of the conditions (Ne ≧ NFB1) are satisfied, the condition that the opening of the intake throttle valve 8 becomes the idle opening by turning on the idle switch 22 (ID switch ON), and the engine rotation The condition that the number Ne is equal to or more than the second feedback control start rotation speed NFB2 (Ne ≧
(Determined vehicle speed) is also set and used.

When the engine speed Ne reaches one of the first and second feedback control start speeds NFB1 and NFB2 set according to the vehicle speed, the first and second target idle speeds NE are set.
Control to be one of NE1 and NE2.

Further, when the condition (Ne ≦ NFB1) that the engine speed Ne is equal to or less than the first feedback control start speed NFB1 is satisfied, the control unit 16 performs the feedback control of the idle speed. Conditions between the first and second feedback control start rotation speeds NFB1 and NFB2 (NFB1 ≧ Ne ≧ NFB
2) In the case of idle speed control duty values DTYA, D
TYB and DTYC have lower limit GARO.

The lower limit value GARD is a case where the duty value during idle speed control before stopping the idle speed control is stored and the duty value is maintained at the stored duty value before the idle speed control is stopped. , There is. At this time, the operation of storing the duty value at the time of the previous idle speed control as the lower limit value GARD is performed by turning on the idle switch 22, as shown in FIG. Elapsed condition (ID switch ON
+ Tilay time) and the condition that the vehicle speed detected by the vehicle speed sensor 24 is lower than the control start vehicle speed (vehicle speed <control start vehicle speed)
A condition that the engine speed Ne is close to the first target idle speed NE1 (Ne = NE1 ± χ); and a condition that the cooling water temperature detected by the temperature sensor 18 is equal to or higher than the set water temperature (cooling water temperature ≧ set water temperature). Is performed only when any of the above is satisfied.

In FIG. 1, reference numeral 26 denotes an air regulator. The air regulator 26 is controlled by an air valve 28 that operates by using the displacement of a temperature-sensitive displacement body such as thermowax.
The air passage 30 provided around the intake throttle valve 8 is opened and closed in accordance with the temperature of the cooling water to correct the amount of intake air to the downstream intake passage 6-2 of the intake throttle valve 8 when the temperature is low. Also, the sign
32 is a combustion chamber, 34 is an exhaust passage, and 36 is a battery.

 Next, the operation will be described with reference to FIG.

When the idle switch 22 is turned off from on during operation of the internal combustion engine 2, the idle speed control device 4 determines the idle speed control duty value of DTYA, DTYB, or DTYC depending on the engine load as shown in FIGS. Set any one.

When the idle switch 22 is turned on from off and the engine speed Ne is equal to or higher than the first feedback control start speed NFB1, the state of the set duty value is maintained,
When the engine speed Ne is between the first and second feedback control start speeds NFB1 and NFB2 (NFB1 ≧ Ne ≧ NFB2) and the vehicle speed is equal to or higher than the determined vehicle speed, the duty value is set to DTYA.

If the engine speed Ne is less than the first feedback control start speed NFB1 and the vehicle speed is lower than the determined vehicle speed, feedback control of the idle speed is performed to set the first target idle speed E1.

In this feedback control, the engine speed
When Ne is NFB1 ≧ Ne ≧ NFB2, a lower limit value GARD is provided for the duty value.

The engine speed Ne is the second feedback control start speed NF
When the vehicle speed is equal to or lower than B2 and the vehicle speed is equal to or higher than the determination vehicle speed, feedback control of the idle speed is performed to obtain the second target idle speed NE2. In this state, if the vehicle speed falls below the determination vehicle speed, the first target idle speed NE1
In this case, feedback control of the idle speed is performed.

The feedback control of the idle speed is performed by the following formula.

In other words, the duty value F /
The B duty value is: F / B duty value = duty value P + duty value I duty value P = ΔNe × coefficient χ ... ΔNe = target engine speed−engine speed ΔNe: coefficient χa when minus, coefficient χb when plus χa <＝ b Duty value I = previous duty value + ΔI... ΔI = ΔNe × coefficient y ΔNe: Coefficient ya when minus. Coefficient ybya <yb when plus. It is determined by a variation with respect to the engine speed.

In addition, the duty value I (integral component) of the equation is obtained by a variation with respect to the target engine speed similarly to the duty value P.

Further, the duty values P and I change the coefficients χ and y multiplied by ΔNe depending on whether the engine speed is higher or lower than the target engine speed, and the engine speed falls below the target engine speed. The recovery has been accelerated.

As a result, the start timing of the idle speed control can be advanced without requiring an additional load switch for detecting the contribution of the electric load or the like.

For this reason, since the start timing of the idle speed control can be advanced, it is possible to prevent the inconvenience of causing the engine stall due to the falling engine speed exceeding the target idle speed. In addition, since it is not necessary to additionally provide a load switch for detecting the load such as an electric load for starting the idle speed control under the condition that the load is equal to or greater than the control start load, the cost does not increase. .

Further, in addition to the stop state, the bypass intake air amount is controlled during idling even during traveling to control the engine speed to be the first and second target idle speeds, and the second feedback control in the deceleration state The start rotation speed is set lower than the first feedback control start rotation speed in the stop state, and the second target idle rotation speed in the deceleration state is set higher than the first target idle rotation speed in the stop state. By doing so, the idle speed control is performed even in the running state in addition to the stop state, and the control start timing at the time of deceleration can be obtained earlier, and the engine speed drops excessively below the target idle speed at the time of deceleration. The problem of engine stall can be prevented.

Further, when the engine speed falls to the second feedback control start speed at the time of deceleration and the idle speed control is started, the first target idle speed at the time of stop is reduced to the first target idle speed at the time of stopping.
By setting the rotation speed higher than the target idle speed, the rotation difference between the second feedback control start rotation speed and the second target idle speed is reduced, and the target idle speed can be controlled with a small control amount. Even if the value fluctuates greatly, there is a margin in the control width, so that the control followability is improved,
The problem of engine stall can be prevented, which is practically advantageous.

〔The invention's effect〕

As described above, according to the present invention, after the idle speed control is stopped due to the failure of any one of the idle speed control start conditions, the condition that the intake throttle valve opening of the internal combustion engine is the idle opening and the vehicle speed If both the condition that is equal to or higher than the control vehicle speed and the condition that the engine speed is equal to or lower than the second feedback control start speed set lower than the first feedback control start speed are satisfied, the control means By starting feedback control of the idle speed so that the engine speed reaches the second target idle speed set higher than the first target idle speed,
In addition to the stop state, the idle speed control is performed even in the running state, so that the control start timing at the time of deceleration can be obtained earlier, and the engine speed falls below the target idle speed at the time of deceleration and engine stall occurs. Failure can be prevented. In addition, since it is not necessary to additionally provide a load switch for starting the idle speed control under the condition that the load is equal to or greater than the control start load, the cost does not increase. Further, at the time of deceleration, when the engine speed falls to the second feedback control start speed and the idle speed control is started, the second target idle speed during traveling is set to be lower than the first target idle speed when stopped. By setting the rotation speed high, the rotation difference between the second feedback control start rotation speed and the second target idle rotation speed is reduced, and the target idle rotation speed can be achieved with a small control amount. , The controllability of the control is improved, and the problem of engine stall can be prevented, which is practically advantageous.

[Brief description of the drawings]

1 to 8 show an embodiment of the present invention, FIG. 1 is a schematic configuration diagram of an idle speed control device, FIG. 2 is a diagram showing conditions for establishing feedback control of the idle speed control device, and FIG. FIG. 4 is a logic circuit diagram of the first and second target idle speeds, FIG. 5 is a diagram showing selection of an idle speed control duty value by an engine load, FIG. 7 is a logic circuit diagram of the duty value DTYA, FIGS. 7 (A), (B), (C), and (D) are timing charts of idle speed control start conditions, and FIG. 8 is a logic circuit diagram of duty value storage. 9 to 12 show a conventional example, FIG. 9 shows the relationship between the cooling water temperature and the target idle speed, and FIG. 10 shows the relationship between the cooling water temperature and the engine speed. FIG. 11 is a logic circuit diagram of an idle speed control start condition, and FIGS. 12 (A), (B), (C), and (D) are timing charts of an idle switch, a duty value, an engine speed, and a load. is there. In the figure, 2 is an internal combustion engine, 4 is an idle speed control device, 6 is an intake passage, 8 is an intake throttle valve, 10 is a surge tank, 12 is a bypass intake passage, 14 is a bypass intake amount control valve, and 16 is a control unit. , 18 is a temperature sensor, 20 is a rotation speed sensor,
22 is an idle switch, and 24 is a vehicle speed sensor.

Claims (1)

(57) [Claims] 1. A condition that an intake throttle valve opening of an internal combustion engine is an idle opening, a condition that a vehicle speed is less than a control vehicle speed, and a condition that an engine speed is less than a first feedback control start speed. When all of the idle speed control start conditions are satisfied, the idle speed control device of the internal combustion engine starts control of a bypass intake air amount that bypasses an intake throttle valve so that the engine speed reaches the first target idle speed. In the above, after the idle speed control is stopped due to failure of any one of the idle speed control start conditions, the condition that the intake throttle valve opening of the internal combustion engine is the idle opening, and the vehicle speed is the control vehicle speed The above condition and the condition that the engine speed is equal to or less than a second feedback control start speed set lower than the first feedback control start speed. A control means is provided for starting feedback control of the idle speed so that the engine speed reaches a second target idle speed set higher than the first target idle speed when these conditions are satisfied. An idle speed control device for an internal combustion engine.