JPH01277648A - Idle speed control device for engine - Google Patents

Abstract

PURPOSE:To prevent an idle speed from its drop by increasing a feedback again when an engine is in the hot time left as decreasing its temperature to a half-warmed condition after warming the engine, in the case of an idle speed control device provided with a feedback means. CONSTITUTION:The hot time of an engine, left as cooled with its temperature reaching a half-warmed condition after warming the engine, is detected by a hot time detecting means G, and by outputting its signal to a correcting means H, a control gain by a feedback means F is corrected so as to be increased. Thus while preventing an idle speed from its drop when a feedback control is started, the engine enhances its responsibility of increasing a speed.

Description

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

(Prior art) Conventionally, the idle speed is feedback-controlled by adjusting, for example, the amount of bypass air so that the idle speed of the engine becomes a predetermined speed. For example, a technique for starting the process after the
This is known as seen in Japanese Patent No. 44431.

(Problem to be Solved by the Invention) However, when performing feedback control of the idle speed as described above, it is necessary to restart the engine from a warm state in which the engine temperature has been left to cool until the warm-up state. However, there is a problem in that the idle speed drops when feedback control is started as the engine shifts to an idle state.

When the engine temperature increases due to engine operation from a cold state, the temperature of the sliding parts of the engine increases due to the characteristics of the road, and the clearance remains approximately constant, so the sliding resistance does not particularly increase. Even when the temperature at which feedback of the idle speed starts is reached, the deviation between the initially set basic control amount and the actual amount required by the engine is small, and stable feedback control can be started.

However, when the engine is left to cool from a warm-up state where the engine temperature has risen sufficiently to a half-warm state as the engine is stopped, the engine temperature decreases due to heat radiation to the outside, so The temperature drop in the cylinder is greater than the temperature drop inside, and while the internal piston is still maintained at a high temperature, the temperature of the outer cylinder part decreases, and the clearance of the sliding part decreases due to the difference in thermal expansion between the two. As a result, the sliding resistance, that is, the mechanical resistance increases, and the required output (for example, required intake air amount) to maintain the idle rotation speed increases. When idle feedback is started using the control characteristics, the idle rotation speed drops because the mechanical resistance is larger than the set value, and there is a delay in the control response until the target rotation speed is reached.

In particular, this rotation feedback control performs control after detecting a change in the idle rotation speed, so feedback is provided when the sliding resistance of the engine increases during a warm restart in a semi-warmed state. Even when switching to control,
After detecting a drop in rotation, the control signal is corrected to increase the rotation speed, and during this control delay, the rotation speed will further decrease. Furthermore, for example, in an engine whose target idle speed is set to a low value in order to improve fuel efficiency, the drop in engine speed during the above-mentioned half-warm-up restart may cause the driver to feel anxious or cause the engine to stop. This may occur.

In addition, when controlling the idle rotation speed, in addition to the rotation feedback control that feedback controls the intake air amount etc. so that the detected idle rotation speed becomes the target rotation speed as described above, it is also possible to In parallel, intake air amount feedback control is performed according to the deviation of the intake air amount so that the expected intake air amount corresponds to the state, etc., and even when the engine speed is not changing, it is There are also known systems that can immediately respond to this problem. In the above case, in order to prevent the rotation feedback and intake air amount feedback from interfering with each other and causing rotation hunting, the control period of the rotation feedback control is set to be slower than the control period of the intake air amount feedback control. Even in such a case, when feedback control is started at the time of half-warm-up and warm restart, the rotational speed increase to the target rotational speed is delayed because the control cycle of the rotational feedback control is slow.

Therefore, in view of the above-mentioned circumstances, the present invention has been developed to reduce the drop in engine speed at the start of feedback control of the idle speed during a warm restart in a semi-warmed state where mechanical resistance increases, which causes rotational fluctuations due to feedback at normal temperature. It is an object of the present invention to provide an engine idle speed control device that can prevent engine idle speed from occurring.

(Means for Solving the Problems) In order to achieve the above object, the air-fuel ratio control device of the present invention provides feedback control of the rotation speed adjustment means so that the idle rotation speed is set to the target rotation speed based on a predetermined control gain. a warm state detection means for detecting a warm time when the engine temperature is left to cool down to a half-warm state; and a feedback means that receives an output of the warm state and detects a warm state. and a correction means for correcting so as to increase the control gain.

FIG. 1 is an overall configuration diagram for clearly showing the configuration of the present invention.

A rotation speed adjustment means is provided for changing the idle rotation speed of the engine E by, for example, adjusting the amount of bypass air through a bypass passage C that bypasses the throttle valve B of the intake passage A, and this rotation speed adjustment means is provided with a feedback means. A control signal is output from F. The feedback means F performs feedback control on the amount of bypass air, etc. so that the engine speed during idling becomes the target speed.

Further, a warm detection means G is provided for detecting a warm time when the engine temperature is left to cool down to a half-warm-up state, and a signal from the warm detection means G is outputted to the correction means H. The correction means H corrects to increase the control gain by the feedback means F when a warm state is detected, and prevents a drop in rotation at the start of feedback control of the idle rotation speed and improves the responsiveness of an increase in rotation. It is intended to be controlled.

(Function) In the engine idle speed control device as described above,
Basically, feedback control is performed so that the idle rotation speed becomes the target rotation speed, and in normal idle operation, the control gain of the feedback control is set low to reduce rotation fluctuations, while the warm detection means When a half-warm restart condition is detected, the control gain in feedback control of the idle rotation speed is increased to reduce the rotation drop that occurs at the beginning of the feedback transition due to an increase in mechanical resistance, and to stabilize the rotation speed to the target rotation speed with good response. That's what I do.

(Example) The present invention will be described in detail below with reference to the drawings.

FIG. 2 is an overall configuration diagram of a specific example.

The combustion chamber 2 of the engine 1 has an intake boat 3 and an exhaust boat 4.
is opened, and the openings of both boats 3 and 4 are opened and closed at predetermined timings by the intake valve 5 and the exhaust valve 6, respectively. The intake passage 7 that communicates with the intake boat 3 and supplies intake air to the combustion chamber 2 includes an air cleaner 8 from the upstream side,
An intake air amount sensor 9 that measures the intake air amount and a throttle valve 10 that controls the intake air amount are interposed, and an injector 12 that injects and supplies fuel is provided downstream of the surge tank 11.

Further, a bypass passage 14 is provided to bypass the throttle valve 10, and a control valve 15 (duty solenoid valve) for adjusting the amount of bypass air is interposed in the bypass passage 14.

The control valve 15 installed in the bypass passage 14 receives a control signal (
A duty signal) is output, and the idle speed is controlled by controlling the amount of bypass air.

In order to detect the operating state of the engine, the controller 16 receives an intake air amount signal from an intake air amount sensor 9 that detects the intake air amount, as well as a rotation signal from a rotation sensor 17 that detects the engine rotation speed, and an engine rotation signal. In order to detect the warm-up state of the engine, a water temperature signal from a water temperature sensor 18 that detects the engine water temperature, an idle signal from an idle switch 19 that is turned on when the throttle valve 10 is fully closed, and the like are input.

Then, when the feedback control condition is satisfied, the controller 16 outputs a control signal to the control valve 15 that corresponds to the bypass air amount according to the deviation between the detected engine speed and the target engine speed in the normal idle state. and performs rotation feedback so that the idle rotation speed becomes the target rotation speed, and outputs a control signal according to the difference between the detected intake air amount and the expected intake air amount to the control valve 15 to maintain the predetermined idle rotation speed. The rotation feedback processing cycle is set longer than the intake air volume feedback processing cycle. In addition, when a half-warm restart state is determined from the water temperature state, the intake air amount feedback is stopped, the rotation feedback processing cycle is shortened, and the amount of correction in the rotation downward direction of this rotation feedback control is modified in the upward direction. This control is performed so as to increase the control gain, reduce the amount of drop in rotational speed, and increase the increase in rotational speed.

Note that the above-mentioned detection at the time of a half-warm restart is performed when the engine temperature when the engine is stopped before restart is equal to or higher than the warm-up completion water temperature (e.g. 80°C), and the water temperature at the time of restart increases mechanical resistance. When the temperature is within a predetermined range (for example, 20 to 80 degrees Celsius), the above-mentioned process is performed as a half-warm restart.

Next, the processing by the controller 16 will be explained based on the flowcharts of FIGS. 3 and 4.

FIG. 3 shows a rotation feedback routine. After an interrupt is started every 100 m5ec, this routine determines in step S1 whether or not the idle rotation speed feedback condition is satisfied based on the detection signals from each of the sensors. This feedback condition is, for example, when the engine rotation speed is below a predetermined rotation speed (for example, 1200 rpm),
Feedback is started when the idle switch 19 is ON (throttle fully open) and there is no load.

Then, when the feedback condition is satisfied, first,
In step S2, the engine rotation N is measured, and in step S3
The rotation range N1 to N where the drop in engine rotation becomes a problem
It is determined whether or not the speed is within Z (for example, 800 to 900 rpm). If this determination is YES, in step S4 the water temperature Tw changes to the temperature range T1 to T2 where mechanical resistance increases (
For example, it is determined whether or not it is time for a warm restart in the range of 20 to 80°C. Note that, as a premise of this determination, it is determined that the water temperature when the engine was stopped last time was equal to or higher than the warm-up completion temperature (for example, 80° C.).

If the determination in step S4 is No and during normal idling operation, after resetting flag F, which will be described later, in step S5,
It is determined whether the counter C has reached 0 or not. 20 Counter C is for setting the output cycle to the control valve 15 by rotation feedback to 500 m5ec, and the initial value is set to 5 in step S7, and this is gradually subtracted in step S10, and the determination in step S6 is performed. When the value becomes 0 (YES), the process proceeds to the step for feedback output.

That is, in step S8, the deviation ΔN between the target rotational speed N0 and the detected rotational speed N is determined, and in step S9, the correction coefficient k is set to 1, and then the process proceeds to step 516, where correction is made from the table according to the deviation ΔN. Air amount ΔQt'b
In step S17, the value obtained by multiplying the corrected air amount ΔQf'b by the correction coefficient k is added to the previous bypass air amount Qo to obtain bypass air ff1Q, and in step 318, the duty signal corresponding to this bypass air ff1Q is determined. It is output to the control valve 15.

On the other hand, when the determination in step S4 is YES and a warm restart is performed after half-warming, a flag F is set to 1 in step Sll to stop intake air amount feedback (FIG. 4), which will be described later. Then, in step S12, a deviation ΔN between the target rotational speed N0 and the detected rotational speed N is determined, and in step S13, it is determined whether or not this deviation ΔN is a negative value. If the determination in step S13 is YES and the detected rotation speed N is higher than the target rotation speed No, the correction coefficient k is set to a small value (
For example, if the determination in step S13 is No and the detected rotational speed N is lower than the target rotational speed No, the correction coefficient k is set to the normal value 1 in step S15. Then, proceeding to step 31B, the deviation Δ
The corrected air amount ΔQfb is determined from the table in accordance with It outputs a duty signal corresponding to air flQ to the control valve 15.

At that time, the detected rotation speed N is higher than the target rotation speed No.
When correcting the bypass air amount in the direction of reducing the engine rotational speed, since the correction coefficient k is set to a small value, the amount of correction is also small, thereby suppressing a reduction in rotational speed. Further, at the time of warm restart after 20-1/2 warm-up, step S6. S7. Since it does not go through SIO processing, the feedback output is 100 at each side entry.
It is performed every m5ec to shorten the processing cycle and improve responsiveness.

Note that even during a warm restart after half-warming up, if the determination in step S3 is NO and the engine speed is high, in order to quickly reduce the idle speed to near the target speed,
Step SL4 is not passed through.

FIG. 4 shows an intake air amount feedback routine, and after this routine starts with an interruption every 75a+sec, it is similarly determined in step S20 whether or not the feedback condition of the idle speed is satisfied.

When the feedback condition is satisfied, it is determined in step S2L whether the flag F has been reset to 0. During normal control when the flag F is reset to 0, the intake air amount Qe is detected in step S22, and the deviation ΔQ between the estimated intake air amount Qmb corresponding to the current operating state and the detected intake air ff1Qe is determined in step 523.
seek. Further, in step S24, the corrected air amount ΔQ['b is determined from the table according to the deviation ΔQ, and in step S25, the corrected air amount ΔQf is added to the previous bypass air mQo.
'b is added to obtain bypass air ff1Q, and a duty signal corresponding to this bypass air ff1Q is output to the control valve 15 in step S2B.

On the other hand, when the determination in step S21 is NOl, that is, when the flag F is set to 1 during a warm restart after half-warming, the intake air amount feedback in steps 823 to S2B is stopped.

In the embodiment described above, during a warm restart after half-warming up when the mechanical resistance of the engine increases, intake air amount feedback is stopped and idle speed control is performed only by rotation feedback, and this idle speed control is also performed. The control gain is increased by shortening the processing cycle and reducing the correction amount in the direction of lowering the engine speed, thereby suppressing the drop in engine speed at the start of feedback and reducing the speed of increase in engine speed. By increasing the number of rotations, the idle rotation speed can be quickly converged to the target rotation speed.

In addition to the above-mentioned embodiments, known methods such as switching the reflection rate of the correction value in the feedback control can be appropriately employed to increase the control gain of the feedback control.

(Effects of the Invention) According to the present invention as described above, when the idle speed is feedback-controlled to set the idle speed to the target speed based on a predetermined control gain, the engine temperature is cooled until the warm-up state is left until the warm-up state. When the warm time is detected, the control gain by the feedback means is corrected to increase.In normal idling operation, the control gain of the feedback control is set low to reduce rotational fluctuations, while the warm time is When a half-warm restart state is detected by the detection means, the control gain in the feedback control of the idle speed is increased to reduce the rotation drop that occurs at the beginning of the feedback transition due to an increase in mechanical resistance, and to adjust the target rotation speed with good response. It is something that can be stabilized in numbers.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram for clearly showing the configuration of the present invention, Fig. 2 is an overall configuration diagram of an engine idle speed control device showing a specific example of the invention, and Figs. 3 and 4 are diagrams of a controller. FIG. 3 is a flowchart diagram for explaining processing. E, 1...engine, D...rotation speed adjustment means, F...feedback means, G.
...Warm detection means, H...Correction means, 9
...Intake air amount sensor, 15...Control valve,
16... Controller, 17... Rotation sensor, 18... Water temperature sensor. Figure 1 Figure 2

Claims (1)

[Claims] (1) Engine idling comprising a rotation speed adjustment means for changing the idle rotation speed, and a feedback means for feedback controlling the rotation speed adjustment means so that the idle rotation speed is set to a target rotation speed based on a predetermined control gain. In the rotation speed control device, there is provided a warm state detecting means for detecting a warm time when the engine temperature is left to cool from warm-up to a half-warm state, and when a warm state is detected by receiving an output of the warm state detecting means. An engine idle speed control device comprising: a correction means for correcting so as to increase a control gain by the feedback means.