JP2917062B2 - Engine idle speed control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an idle speed control device for an engine that performs feedback control of an idle speed to a target speed.

[0002]

2. Description of the Related Art Conventionally, an intake air amount, an ignition timing, and the like are adjusted based on a control signal corresponding to a deviation between the two so that an idle speed of an engine becomes a predetermined target speed, thereby obtaining idle stability. Since the power generation load of the alternator changes according to the operation state of the electric load and affects the idle speed, as disclosed in Japanese Patent Application Laid-Open No. 2-130244, for example, A technique for controlling the idle speed in accordance with the output current of the alternator is also known.

[0003] The idle speed control according to the output current of the alternator is performed by turning on an electric load such as driving an air conditioning fan or turning on a headlamp in accordance with the current consumed by the electric load. Since the drive load of the motor increases and the idle speed decreases due to the increase of the drive load, the operation of the electric load is detected from the output current of the alternator before the idle speed actually decreases, and the idle speed increases. The correction control is performed in the direction in which the correction is performed.

[0004]

According to the above-described correction control in which the idle speed is increased in accordance with the output current of the alternator, the electric load is instantaneously turned on when the electric load is turned on. A rush current to the load (rush current) is generated, and the generated current of the alternator increases instantaneously, then decreases once and then changes to a characteristic that becomes a steady current (see FIG. 7). On the contrary, the idle control may become unstable due to the correction control, and hunting may occur, and the engine may stop due to a drop in rotation.

That is, in response to the above-described change in the generated current of the alternator, the generated current instantaneously exceeds the operation determination level of the electric load when the rush current occurs, and it is determined that the electric load is on. Correction control is performed to increase the rotation speed and reduce the idle rotation speed due to the increase in the electric load. Immediately thereafter, the alternator generated current decreases below the operation determination level, and the steady state becomes higher than the operation determination level again. When the current value rises, the target rotational speed is also corrected to be lowered by the determination that the electric load is actually operating but temporarily turned off, and the driving load is increased by the operation of the electric load. However, the target rotation speed is low, causing a drop in rotation, which reduces the alternator's generated current and delays the correction of the rotation speed, causing a large rotation drop. In some cases it leads to a down stop.

In view of the above circumstances, an object of the present invention is to provide an idle speed control device for an engine which can improve the instability of the idle speed due to rush current.

[0007]

In order to achieve the above-mentioned object, an engine idling speed control apparatus of the present invention, as shown in FIG. An idle speed adjusting means F for changing an idle speed is provided, and the idle speed is set to a target by setting a control amount corresponding to a deviation between the actual idle speed and the target speed for the idle speed adjusting means F. A control signal is output from feedback means G for performing feedback control on the number of revolutions. The target speed in the feedback means G is set by a target speed setting means H described later.

The engine E is provided with an alternator J that is rotated and driven by the engine to generate electric power. The alternator J changes the generated current according to the operation of the electric load K and the engine speed. A current sensor M for detecting the generated current of the alternator J is provided, and a detection signal of the current sensor M is output to the operation determining means P via the limiting means N. The operation determining means P compares the current value detected by the current sensor M with the set value, and determines that the electric load K has been operated in the ON operation state when the generated current is equal to or larger than the set value. . A determination signal of the operation state of the electric load K by the operation determination means P is output to the target rotation speed setting means H. When the electric load K is in the operation state, the target rotation speed setting means H outputs the feedback signal. The setting is changed so as to increase the target rotation speed of G.

The limiting means N receives the signal from the current sensor M and sets the target rotation speed based on the generated current by the target rotation speed setting means H when the degree of change in the generated current of the alternator J is large. It functions to limit the change. This limiting means N is, for example,
When a predetermined smoothing process is performed on the current value used in the operation determining means P, and when the degree of change in the generated current of the alternator J is large, the reflection rate of the change is reduced to slow down, and the electric load K is changed by the rush current fluctuation. The change of the target rotation speed is limited so as not to affect the operation determination of the target rotation speed. The limitation on the change of the target rotation speed includes not only changing the target rotation speed but also reducing the change amount of the target rotation speed with respect to the variation amount of the electric load.

[0010]

In the engine idle speed control device as described above, basically, the idle speed is feedback-controlled to the target speed by the feedback means, and the generated current of the alternator detected by the current sensor is controlled. Is greater than or equal to the set value, it is determined that the electric load is in the operating state, the target rotational speed is increased, and a decrease in the engine rotational speed due to an increase in the drive load of the alternator is suppressed. When the degree of change of the generated current such as rush current during operation is large,
Limiting means restricts the change of the target rotation speed corresponding to the sudden change of the generated current, and prevents the occurrence of hunting due to an over-control state accompanying the change of the target rotation speed or the engine stop due to a drop in the rotation speed. Stable idle speed control can be performed.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is an overall configuration diagram of an engine including an idle speed control device according to one embodiment.

An intake port 4 and an exhaust port 5 communicate with each other in a combustion chamber 3 formed above the piston 2 of the engine body 1 so as to be variable in volume. Is opened and closed.

An intake passage 8 connected to the intake port 4
An air flow sensor 11 for detecting the amount of intake air from the upstream side and a throttle valve 12 are interposed, and a downstream portion of a surge tank 13 is formed to be branched into each cylinder, and an injector 14 for injecting and supplying fuel is provided here. Have been.

A bypass air passage 15 is formed in the intake passage 8 so as to bypass the throttle valve 12 and to be connected to the upper and lower intake passages 8. A control valve 16 for adjusting the amount of air is interposed. Further, an ignition plug 17 is provided facing the combustion chamber 3, and a discharge voltage is supplied to the ignition plug 17 via an ignition coil 18 and a distributor 19 to adjust the ignition timing.

On the other hand, an alternator 30, which is rotated and driven by a crankshaft (not shown) of the engine body 1 to generate electric power, is provided. It is configured to supply power to the electric load 32 and to charge the battery 33, and to supply power from the battery 33 to the electric load 32 when the amount of power generated by the alternator 30 is insufficient. I have. Further, a current sensor 34 for detecting the generated current of the alternator 30 is provided.

A control signal is output from the controller 20 to the ignition coil 18 to control the ignition timing in accordance with the operating state. At the time of idling, the control of the ignition timing controls the idle speed to the target speed. Idle speed control for feedback control is performed. Further, the bypass air control by the control valve 16 of the bypass air passage 15 and the fuel injection control of the injector 14 are performed according to the operation state by the control signal from the controller 20.

The controller 20 includes a rotation signal for detecting the engine speed from a distributor 19, an intake air amount signal from an air flow sensor 11, an engine water temperature signal from a water temperature sensor 22, and a throttle valve 12 for detecting an operation state. A signal from the idle switch 23 that operates in the fully closed state, a shift sensor that detects the neutral position of the transmission
24, a signal from a clutch switch 25 for detecting the engaged / disengaged state of the clutch, a signal from a cooler switch 27 for operating the operation of a cooler compressor, and a detection signal of a generated current from the current sensor 34. You.

Further, the controller 20 performs the feedback control of the idle speed to the target speed by setting a control amount in accordance with the deviation between the idle speed and the target speed. The function of the operation determining means P for determining that the electric load 32 is in the operating state when the current value detected by the sensor 34 is equal to or more than the set value, and the target rotation speed of the feedback means G when the operating state of the electric load 32 is determined. The function of the target rotation speed setting means H for changing the current sensor
When the alternator 30 receives the signal of 34 and the degree of change in the generated current of the alternator 30 is large, the alternator 30 has a function of limiting means N for limiting the change in the target rotation speed based on the generated current.

The processing of the controller 20 will be described with reference to the flowcharts of FIGS. FIG. 3 shows a processing routine for the generated current el (5 ms routine). In step S1, the generated current el of the alternator 30 is input from the value obtained by A / D converting the output signal of the current sensor 34. And step S
In step 2, the average value eld of the generated current el is calculated. This smoothed value eld is used as a generated current in a later process, and is calculated by a smoothing process (smoothing process) using a digital low-pass filter.
(i-1) is multiplied by 0.863, and this detection generated current el
Multiplied by 0.137 and add the average value eld (i)
It is calculated using a weighted average method to find out, even if the detected generated current el fluctuates suddenly, the effect is reduced and the fluctuation amount of the smoothed value eld (i) is reduced. . The reflection ratio can be arbitrarily changed.

Subsequently, in step S3, the above-mentioned average value el
The operation state of the electric load 32 is determined with hysteresis by comparing d (i) with the set value 30A or 33A, and the operation flag Xel as an electric load internal switch is updated and set. The operation flag Xel is set to 1 when the smoothed value eld is higher than a set value as the operation state of the electric load 32, and is reset to 0 as the operation state of the electric load 32 when the average value eld is lower than the set value. Then, after the processing of the detected current el as described above, the target rotational speed No of the engine is calculated in step S4.

The calculation process of the target rotational speed No is shown in a subroutine (5 ms routine) of FIG. 4. In step S11, the reference target rotational speed Nobs under no load condition is calculated. The reference target rotational speed Nobs is obtained from the table of characteristics shown in FIG. 8 corresponding to the engine water temperature, and a stable idle rotation can be obtained in a no-load state where the electric load 32 and the air conditioner load are not applied. The engine speed is set to a higher value as the engine water temperature is lower.

Step S12 determines whether or not the cooler switch 27 is on. If the determination is YES and the cooler compressor is being driven, the process proceeds to step S12.
In step S13, a predetermined value 860 rpm is set to the correction target rotation speed Not. Then, in step S14, it is determined whether or not the reference target rotation speed Nobs is greater than the correction target rotation speed Not (860 rpm). If it is higher, the correction target rotation speed Not is written in step S15 with the reference target rotation speed Nobs. Replace. When the cooler switch 27 is off, the reference target rotational speed Nobs is written in the corrected target rotational speed Not.

Next, at step S16, the operation flag Xel set according to the operation of the electric load 32 in the routine of FIG.
Is set to 1 or not.
If the electric load 32 is operating in the ES, step S17
Then, it is determined whether or not the correction target rotation speed Not is lower than a predetermined value 810 rpm. If it is low, the correction target rotation speed Not is rewritten to a predetermined value 810 rpm in step S18.

The correction target rotation speed N set as described above
In step S19, it is determined whether or not ot is higher than the current target rotation speed No. If it is higher, in step S20, the target rotation speed No is corrected so as to be increased by 10 rpm. If it is not high, it is determined in step S21 whether or not the corrected target rotational speed Not is lower than the target rotational speed No. If it is lower, in step S22, the target rotational speed No is corrected so as to be reduced by 10 rpm. Note that the target rotation speed N in steps S20 and S22
The correction of o is clipped to the value of the correction target rotation speed Not when the difference from the correction target rotation speed Not is small.

FIG. 5 shows a routine (20 ms routine) for determining the execution of the ignition feedback control of the idle speed.
In step S31, various signals are input, and in steps S32 to S35
To determine the feedback start condition. That is, in step S32, it is determined whether or not the engine rotation speed Ne is higher than 500 rpm and the start is completed. In step S33, similarly, whether or not the engine rotation speed Ne is lower than the rotation speed obtained by adding the predetermined value 500 rpm to the target rotation speed No. Is determined. In step S34, it is determined whether or not the vehicle is in a stopped state with no load. Further, in step S35, it is determined whether or not the idle switch 23 is in the ON state with the throttle fully closed.

If the engine speed Ne is in an idling state within a predetermined range (500 rpm <Ne <No + 500 rpm), it is determined in step S36 whether or not a feedback execution flag Xafb described later is set to 1. I do.
If this determination is NO and it has not yet been set, it is determined in step S37 whether or not the engine speed Ne has become equal to or less than the target rotation speed No. If this determination is YES, the feedback execution flag Xafb is set in step S38. Set to 1 to start feedback control. Under conditions other than the above, the feedback execution flag Xaf is determined in step S39.
Reset b to 0 to stop feedback control.

Next, FIG. 6 shows a feedback routine of the idle speed based on the ignition timing, which is processed at every 180 ° of the crank angle. In step S41, the idle retard amount thret is obtained from the table. In step S42, a basic advance value thtbse at which the torque becomes highest is obtained from the map. This idle retard amount thret is used to shift to a slightly lower torque ignition timing in order to perform feedback control. I have to. Then, step S43
Then, it is determined whether or not the feedback execution flag Xafb set in the routine of FIG. 5 is set to 1.

If the determination in step S43 is YES and the feedback execution condition is satisfied, the process proceeds to step S43.
At 44, it is determined whether or not the current engine speed Ne is higher than the target engine speed No. When the engine speed Ne is equal to or lower than the target speed No, a feedback correction advance value thtfb is calculated in step S45 to advance the ignition timing. This corrected advance value thtfb is determined by the idle retard amount thtr.
et at 120rpm the difference between the engine speed Ne and the target speed No
Multiply by the ratio divided by. On the other hand, step S44
Is YES and the engine speed Ne is equal to the target speed No.
If higher, step S46 is performed to retard the ignition timing.
Calculates the feedback correction advance value thtfb. The corrected advance value thtfb is obtained by subtracting the difference between the engine speed Ne and the target speed No by 120r from the negative value of the idle retard amount thtret.
Multiply by the ratio divided by pm. The step S
If the determination at 43 is NO and the feedback condition is not satisfied, at step S47 the feedback correction advance value th
Set tfb to 0. Then, the feedback correction advance value thtfb set as described above and the basic advance value thtbse are set.
In step S48, the final advance value thtig is calculated.

The characteristics of the idle speed control during the operation of the electric load based on the control of the controller 20 as described above will be described with reference to the time chart of FIG. First, (A) shows a change in the alternator generated current el. When the load switch 31 is closed and power supply to the electric load 32 is started, the generated current is instantaneously increased as the load current increases. Although the load current increases, the load current further increases as a rush current, whereas the generated current reaches the upper limit (70 A) at the limit of the power generation capacity, and beyond that, current is supplied from the battery 33, and the power is generated according to the decrease in the load current. Although the current also decreases rapidly, the generated current decreases as it is and the overshoot state decreases even though the degree of reduction of the load current gradually decreases in the middle, and then stabilizes to a steady current according to the size of the electric load 32. . In addition,
In the reduction stage, the generated current is lower than the load current and the insufficient current is supplied from the battery 33. The generated current el changing as described above is detected by the current sensor 34,
Is converted to a smoothed value eld as shown by a broken line by the smoothing process (smoothing process).

Then, the ON operation determination level of the electric load 32 is determined.
As a result of the determination of the operation of the electric load 32 by comparison with 30A, the operation flag Xel is set to 1 at the point c in the rising process after the rush current and the operation of the electric load 32 in the present invention of FIG. With this determination, the target rotational speed No gradually increases to match the corrected target rotational speed associated with the operation of the electric load 32, and the feedback control associated therewith, that is, the idle rotational speed Ne and the target rotational speed Ne, are performed. A lead angle feedback correction value is calculated from the deviation from the number No, and the ignition timing is advanced when the target rotational speed No increases, the rotational speed is increased by increasing the torque, and the ignition timing is increased when the target rotational speed No decreases. The actual idle speed Ne does not fluctuate during the rush current and gradually rises after the point c to reach the target speed No. It is stable.

On the other hand, in the comparative example shown in (C), the generated current el detected by the current sensor 34 is directly used as the electric load.
The operation flag Xel 'is set to 1 between the point a when the rush current rises sharply and the point b when the rush current suddenly falls by comparing the on-operation determination level 30A with the on-operation determination level 30A. Then, the operation of the electric load 32 is determined, and is set to 1 again at the point d in the rising process after the rush current. Since the rotation speed No 'is set high and is set low in the non-operation determination between b and d, the engine rotation speed Ne' is accompanied by the feedback control corresponding to the reduction of the target rotation speed No 'between b and d. The drop of the large (about 100rp
m) This may cause the engine to stop at this time. Such a variation does not occur in the above-described present invention.

According to the above-described operation, the engine speed is hardly affected by the sudden change in the current generated by the alternator 30 when the electric load 32 is operated. A stable idle operation can be secured by not reacting sensitively in the smoothing process (smoothing process) of the generated current of the alternator 30 so as not to change the target rotation speed.

In the above-described embodiment, an example has been shown in which the idle speed is feedback-controlled to the target speed by adjusting the ignition timing. However, the feedback control of the idle speed is also performed by adjusting the bypass air amount. The present invention is also applicable to the case where the correction control according to the generated current of the alternator 30 is performed. Further, in the above-described embodiment, the target rotation speed is not substantially changed by performing smoothing by a smoothing process that reduces the influence rate of the new detection value instead of using the detection value of the generated current by the current sensor 34 as it is. However, when a sudden change in the generated current is detected, the amount of change in the target rotation speed may be reduced.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram of an engine idle speed control device of the present invention.

FIG. 2 is a schematic configuration diagram of an engine including an idle speed control device according to an embodiment of the present invention.

FIG. 3 to FIG. 6 are flowcharts for explaining processing of a controller, respectively;

FIG. 7 is a time chart showing, together with a comparative example, a variation in the generated current of the alternator during an electric load operation and an example of idle speed control based on the variation.

FIG. 8 is a characteristic diagram showing a table in which a reference target rotation speed is set in accordance with an engine coolant temperature;

[Explanation of symbols]

 1 Engine body 17 Spark plug 20 Controller 30, J Alternator 32, K Electric load 34, M Current sensor G Feedback means H Target speed setting means N Limiting means P Operation judging means

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Hideki Kobayashi 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd. (56) References JP-A-59-1555547 (JP, A) JP-A-2 -146241 (JP, A) JP-A-2-185646 (JP, A) JP-B-60-38544 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) F02D 41/16

Claims (2)

(57) [Claims] A feedback means for feedback-controlling the idle speed to a target speed by setting a control amount according to a deviation between the idle speed and the target speed; a current sensor for detecting a generated current of the alternator; An operation determining unit that determines that the electric load is in an operating state when a current value detected by a current sensor is equal to or greater than a set value; and a target rotation speed of the feedback unit when the operating state of the electric load is determined by the operation determining unit. And a target speed setting means for changing the output speed of the alternator to a higher value. An engine eye comprising a limiting means for limiting a change in a target rotation speed based on a generated current. Dollar rotation speed control device. 2. The idle speed control device for an engine according to claim 1, wherein the limiting means performs a predetermined smoothing process on a current value used by the operation determining means.