JPH07103826B2 - Idle speed control device for internal combustion engine - Google Patents

Description

Description: Outline When an internal combustion engine is idle, a determination level is set according to the rotational speed or the difference between the rotational speed and a target rotational speed, and the time change rate of the rotational speed exceeds the determination level. The fluctuation of the rotation speed is detected when
The control amount of the flow control valve provided in the bypass side passage for idling is suddenly changed. Accordingly, when the time rate of change of the rotation speed becomes close to zero, the target value of the parameter related to the torque of the internal combustion engine at that time can be set, and the target value can be maintained or gently changed. The control amount of the flow rate control amount is rapidly changed to the value.

Therefore, for example, when the rotation speed drops, the intake air flow rate is increased at a relatively large time rate of change, and engine stall can be prevented. Further, when the time change rate of the rotational speed starts to rise after reaching the minimum value, the intake air flow rate is sharply reduced to a value at which the torque at that time can be maintained, so that so-called upward blowing due to overcontrol is prevented. . In this way, when the rotation speed is unstable, a slight change in the rotation speed is detected sensitively, and control is performed with a high control gain. On the other hand, when the rotation speed is high and stable, unnecessary control operation is prevented and safety is improved. In addition, the target rotation speed is changed, so that the rotation speed can be quickly converged even if the rotation speed is far from the target rotation speed.

FIELD OF THE INVENTION The present invention relates to a device for controlling the idle speed of an internal combustion engine.

2. Description of the Related Art In an internal combustion engine, the rotational speed fluctuates due to a slight load fluctuation during idling when a small torque is generated. For example, the rotation speed drops when the power load of an audio device or the like, the use of an air conditioner or the like is started, and the power steering is stationary or the D range of the automatic transmission is turned on.

On the other hand, in recent years, the idle rotation speed has been kept relatively low in order to improve fuel economy, and therefore, if the factors causing the load fluctuation as described above are duplicated, there is a risk of engine stall.

Therefore, in a typical conventional technique, the control device for controlling the flow control valve provided in the bypass side passage for idling incorporates the outputs of various devices and the detection results of sensors that cause load fluctuations, for example, When the air conditioner is used, the idle rotation speed is controlled by increasing the idle rotation speed by 250 rpm. Further, integral control is performed with a small control gain for suppressing overcontrol so that the rotation speed thus set is obtained.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In the above-described related art, the control device needs to capture outputs from various devices and detection results of sensors,
The structure becomes complicated and the cost increases. Further, since the control gain is low, the response is poor, and it takes a long time to reach the target rotation speed. On the other hand, if the control gain is increased, the response is improved but the stability is deteriorated. In other words, over-control occurs, resulting in over-control, which causes an undesired situation such as so-called hunting blow-up.

An object of the present invention is to provide an idle speed control device for an internal combustion engine, which can have a simplified structure, improved stalling resistance, and both responsiveness and stability.

Means for Solving the Problems According to the present invention, the upstream side and the downstream side of a throttle valve are communicated with each other by an idle bypass side passage, and a control amount of a flow control valve provided in the side passage is changed. In the idle rotation speed control device of the internal combustion engine for maintaining the rotation speed of the internal combustion engine at a predetermined target rotation speed, a determination level is set according to the rotation speed, and the time change rate of the rotation speed is equal to or lower than the determination level. The control amount is rapidly increased with a relatively large change rate, and at the time when the time change rate of the rotation speed becomes zero or almost zero, the parameter related to the torque of the internal combustion engine at that time is changed. An idle speed control device for an internal combustion engine, wherein a target value is set, and the control amount is rapidly reduced to a value that can maintain or gently change the target value. A.

Further, according to the present invention, the upstream side and the downstream side of the throttle valve are communicated with each other by a bypass bypass passage for idling, and the rotational speed of the internal combustion engine is changed by changing the control amount of the flow control valve provided in the bypass passage. In an idle speed control device for an internal combustion engine that maintains a predetermined target rotation speed, a determination level is set according to the rotation speed, and a time change rate of the rotation speed is relatively higher than the determination level. The control amount is rapidly increased with a large change rate, and when the time change rate of the rotational speed becomes zero or almost zero, the target value of the parameter related to the torque of the internal combustion engine at that time is set, The idle speed control device for an internal combustion engine is characterized in that the control amount is rapidly increased to a value at which the target value can be maintained or gently changed.

Further, according to the present invention, the upstream side and the downstream side of the throttle valve are communicated with each other by a bypass bypass passage for idling, and the rotational speed of the internal combustion engine is changed by changing the control amount of the flow control valve provided in the bypass passage. In an idle speed control device for an internal combustion engine that maintains a predetermined target rotation speed, a determination level is set according to the difference between the rotation speed and the target rotation speed, and the time change rate of the rotation speed is equal to or higher than the determination level. The control amount is suddenly increased with a relatively large change rate when, and at the time when the time change rate of the rotational speed becomes zero or almost zero, the parameter related to the torque of the internal combustion engine at that time is changed. An idle speed control device for an internal combustion engine, characterized in that a target value is set, and the control amount is sharply reduced to a value that can maintain or slowly change the target value. It

Further, according to the present invention, the upstream side and the downstream side of the throttle valve are communicated with each other by a bypass bypass passage for idling, and the rotational speed of the internal combustion engine is changed by changing the control amount of the flow control valve provided in the bypass passage. In an idle speed control device for an internal combustion engine that maintains a predetermined target rotation speed, a determination level is set according to the difference between the rotation speed and the target rotation speed, and the time change rate of the rotation speed is equal to or higher than the determination level. Then, the control amount is rapidly reduced with a relatively large change rate, and when the time change rate of the rotational speed becomes zero or almost zero, the parameter related to the torque of the internal combustion engine at that time is changed. An idle speed control device for an internal combustion engine, characterized in that a target value is set, and the control amount is rapidly increased to a value at which the target value can be maintained or gently changed. It

Further, the present invention is characterized in that the parameter is a value related to an intake pipe pressure or a product value of the intake pipe pressure and a rotation speed.

Further, the present invention is characterized in that the intake pipe pressure is obtained in consideration of a response delay of the torque generated by the internal combustion engine with respect to a change in the control amount of the flow control valve.

According to the present invention, when the internal combustion engine is idle, the determination level is set according to the rotation speed or the difference between the rotation speed and the target rotation speed, and the time change rate of the rotation speed exceeds the determination level. At times, fluctuations in the rotational speed are detected, and the control amount of the flow control valve provided in the bypass side passage for idle is rapidly changed at a relatively large rate of change. As a result, when the time rate of change of the rotational speed becomes close to zero, the torque of the internal combustion engine at that time, such as the intake pipe pressure or the value related to the product value of the intake pipe pressure and the rotational speed, becomes A target value of a related parameter is set, and the control amount of the flow control valve is rapidly changed to a value that can maintain or slowly change the target value.

Therefore, when the rotation speed is decreased, the intake air flow rate is increased at a relatively large time rate of change, and the engine stall can be prevented. Further, when the time change rate of the rotational speed starts to rise after passing zero, the intake air flow rate is rapidly reduced to a value at which the torque at that time can be maintained, so that so-called upward blowing due to overcontrol is prevented.

In this way, when the rotation speed is low and unstable, a slight change in the rotation speed is detected sensitively, and control is performed with a high control gain. On the other hand, when the rotation speed is high and stable, unnecessary control operation is prevented and stability is improved. Further, even if the target rotation speed is changed and the rotation speed is far from the target rotation speed, the target rotation speed is quickly converged.

First Embodiment FIG. 1 is a block diagram showing a control device 1 for an internal combustion engine and a configuration related thereto according to an embodiment of the present invention. Inlet 2
The combustion air introduced from the air is purified by the air cleaner 3, and the inflow amount of the combustion air is adjusted by the throttle valve 5 interposed in the intake pipe 4 through the intake pipe 4, and then the surge tank 6
Flow into. Combustion air flowing out of the surge tank 6 is mixed with fuel injected from a fuel injection valve 8 interposed in an intake pipe 7 and supplied to a combustion chamber 11 of an internal combustion engine 10 via an intake valve 9. A spark plug 12 is provided in the combustion chamber 11, and exhaust gas from the combustion chamber 11 is discharged through an exhaust valve 13 and is discharged from the exhaust pipe 14 into the atmosphere through a three-way catalyst 15.

The intake pipe 4 is provided with an intake air temperature detector 21 for detecting the temperature of intake air, a throttle valve opening detector 22 is provided in association with the throttle valve 5, and the surge tank 6 is provided with an intake pipe 7 An intake pressure detector 23 for detecting pressure is provided. A cooling water temperature detector 24 is provided near the combustion chamber 11, an oxygen concentration detector 25 is provided upstream of the three-way catalyst 15 in the exhaust pipe 14, and a downstream side of the three-way catalyst 15. An exhaust temperature detector 26 is provided. The rotation speed of the internal combustion engine 10, that is, the number of rotations per unit time is determined by the crank angle detector.
Detected by 27.

In the control device 1, together with each of the detectors 21 to 27, a vehicle speed detector 28 and a start detector 29 that detects whether or not a starter motor 33 that starts the internal combustion engine 10 is activated.
When an automobile equipped with the internal combustion engine 10 is equipped with an automatic transmission, an air conditioner detector 30 for detecting the use of an air conditioner, etc., and whether or not the shift stage of the automatic transmission is in the neutral position The detection result from the neutral detector 31 for detecting is input.

Furthermore, the controller 1 is energized by the battery 34, and the controller 1 detects the detection results of the detectors 21 to 31 and the battery 34 detected by the voltage detector 20. The fuel injection amount, the ignition timing, etc. are calculated based on the power supply voltage and the like, and the fuel injection valve 8 and the spark plug 12 are calculated.
And control.

The intake pipe 4 is also formed with a side passage 35 that bypasses the upstream side and the downstream side of the throttle valve 5.
A flow control valve 36 is provided at 35. Flow control valve 36
Is duty-controlled by the control device 1, and adjusts and controls the flow rate of combustion air at the time of idling when the throttle valve 5 is almost fully closed. The control device 1 also drives the fuel pump 32 when the internal combustion engine 10 is operating.

FIG. 2 is a block diagram showing a specific configuration of the control device 1. The detection results of the detectors 20 to 25 are output from the input interface circuit 41 via the analog / digital converter 42.
It is given to the processing circuit 43. Further, the detection results of the detectors 22, 27 to 31 are given to the processing circuit 43 via the input interface circuit 44. The processing circuit 43 is provided with a memory 45 for storing various control maps and learning values, and the processing circuit 43 has the above-mentioned battery 34.
Is supplied via the constant voltage circuit 46.

The control output from the processing circuit 43 is an output interface circuit.
47 and is supplied to the fuel injection valve 8 to control the fuel injection amount, and is supplied to the ignition plug 12 via the igniter 48 to control the ignition timing, and further to the flow rate control valve 36. The flow rate of the inflowing air through the side passage 35 at the time of idling is controlled and the fuel pump 32 is driven.

The detection result of the exhaust temperature detector 26 is given to the exhaust temperature detection circuit 49 in the control device 1, and when the detection result is abnormally high, the warning lamp 51 is turned on via the drive circuit 50.

FIG. 3 is a timing chart for explaining the operation of the control device 1 configured as described above. It is assumed that the air-fuel ratio control is being performed based on the output from the oxygen concentration detector 25 and the like. As shown before time t1 in FIG. 3 (2), when the rotational speed NE of the internal combustion engine 10 is relatively stable, the control duty of the flow control valve 36 is based on the actual rotational speed NE. The advance rotation speed NEADV and the target rotation speed N that are predicted and obtained as follows.
From the difference from T, as shown in FIG. 4 (2), integral control is performed in increments of a relatively small increment ΔD1.

In performing the integration control, as shown in FIG. 4 (1), the target rotation speed NT is used as a center, for example, ± 15
A dead zone W1 of rpm is provided, and the integral control is stopped when the advance rotational speed NEADV is within this dead zone W1, and is executed when it is outside W1. During steady operation of the internal combustion engine 10, the rotational speed NE is stable within this dead zone W1.

The prediction calculation of the advance rotational speed NEADV is performed as follows. First, the rotational speed NE, which is the number of revolutions per unit time, is calculated based on the first equation from the time T180 required for the crankshaft to rotate by 180 ° CA.

Next, the rotation speed NEO at the previous calculation timing,
180 ° C from the rotational speed NE at the current calculation timing
The change amount ΔNEa of the rotation speed NE between A is calculated. That is, ΔNEa = NE−NEO (2) From the change amount ΔNEa thus obtained, using the third equation,
The change rate ΔNE converted per unit time (32 msec) is obtained.

Further, from the rate of change ΔNE and the advance time TADV based on the difference between the rotation speed NE and the target rotation speed NT shown in FIG. 5, the advance rotation speed NEADV is obtained by the fourth equation.

By using the advance rotational speed NEADV obtained in this way, it is possible to prevent overshoot due to overcontrol, and to increase the gain during integral control, that is, to increase the increment ΔD1 relatively. It is possible to improve stability.

Further, the increment ΔD1 of the integral control is, as shown in FIG. 6, when the difference between the advance rotational speed NEADV and the target rotational speed NT is within the dead zone W1 of NT ± 15 rpm as described above. It is set to zero, and is set to a value corresponding to the difference NEADV-NT outside the dead zone W1. Thus, at steady state, the rotation speed NE
Are controlled to enter the dead zone W1.

The target rotation speed NT is set to 700 rpm when there is no load, and is set to 950 rpm when the air conditioner is used.

As shown in FIG. 3 (1) at time t1, when the gear position of the automatic transmission is switched from the neutral position to the drive position by the neutral detector 31, the load on the internal combustion engine 10 increases and the rotational speed NE Starts to drop as shown in FIG. 3 (2).

Due to this drop, the rate of change ΔNE is shown in Fig. 3 (3).
When the rotation speed NE is less than a predetermined threshold L2 and the rotation speed NE is less than a threshold L4 higher than the target rotation speed NT by 100 rpm, for example, as shown in FIG. A relatively large increment ΔD2 corresponding to the change rate ΔNE is added to the calculated value of the control duty of the control valve 36, whereby the intake pressure of the surge tank 6 is increased as shown in FIG. 3 (5). P _M rises sharply and the intake air flow rate increases.

As shown in FIG. 7, the relationship between the rate of change ΔNE and the increment ΔD2 is such that when it is greater than one threshold L2 smaller than zero and less than the other threshold L1 larger than zero, Δ
It is set to the dead zone W2 of D2 = 0. The rate of change ΔNE
Is less than the threshold value L2 and more than L1, the increment ΔD2 is set corresponding to the rate of change ΔNE.
The graph shown in FIG. 7 and the graphs shown in FIGS.
The graph shown in the figure is stored as a map in the memory 45 in advance.

The decrease of the rotational speed NE is suppressed by the increase of the intake air flow rate, and the change rate ΔNE goes through the minimum state at the time t3, and then, at the time t4, as shown in FIG.
When the NE exceeds the threshold L2 and enters the dead zone W2 again, that is, when the rate of change ΔNE becomes substantially zero, the parameter related to the intake air flow rate becomes substantially equal to a target value α described later (time t4a), The calculated control duty value is repeatedly subtracted by a predetermined value ΔD3 as shown in FIG. As a result, excessive control is suppressed due to the delay in the response of the torque generated by the internal combustion engine 10 to the change in the control duty.

Further, when a parameter described later becomes substantially equal to the target value α, at that time, the control duty set in advance is set to 2
After the increment ΔD4 of about 3% is added, the integral control corresponding to the difference between the actual rotation speed NE and the target rotation speed NT is performed.

However, even if this control does not stabilize the rotation speed NE well and shows an increase, the rate of change ΔNE becomes equal to or greater than the threshold value L1 as shown at time t5, and the rotation speed NE
Exceeds a threshold value L3 lower than the target rotation speed NT by, for example, 50 rpm, the control duty is subtracted by an increment ΔD2 corresponding to the rate of change ΔNE, as shown in FIG. When the rate of change ΔNE enters the dead zone W2 in this way, the control duty is repeatedly increased by the increment ΔD3 at the time t6, and when the parameter to be described later becomes substantially equal to the target value α, at that time, the control duty is preset to 2 to 2. After the increment ΔD4 of about 3% is added, the integral control corresponding to the difference between the actual rotation speed NE and the target rotation speed NT is performed. In this way, the intake pressure P _M becomes stable as shown in FIG. 3 (5).

In the present embodiment, the value of the increment ΔD2 is set according to the value of the rate of change ΔNE. However, when the capacity of the flow control valve 36 is small or when the capacity of the surge tank 6 is large, the value of the increment ΔD2 is increased.
There is no problem even if the value of D2 is constant. That is, if the decrease in the rotational speed NE is detected, the flow rate control valve 36 will be fully opened,
Even if it is controlled to be almost fully closed by detecting an increase in the rotational speed NE,
Equivalent performance can be obtained.

Further, as shown from time t7 onward, when the shift stage of the automatic transmission is switched to the neutral position, the rotation speed NE increases and is quickly stabilized by the same operation.

The threshold value L2, which is the determination level, is a value obtained by subtracting the correction value h1 shown in FIG. 9 from the value KDPC obtained corresponding to the rotation speed NE shown in FIG. 8, that is, KDPC-h1,
It is set to the larger value of the value KDPCa updated by the change rate ΔNE. Therefore, L2 = max (KDPC-h1, KDPCa) (5) The value KDPC is set such that when the rotational speed NE is 600 rpm or less, the change rate ΔNE per 32 msec is set to 9.375 rpm, and the rotational speed NE is 21.875 rpm when above 800 rpm
When the rotation speed NE is 600 to 800 rpm, the rotation speed NE is set between 9.375 and 21.875 rpm in proportion to the rotation speed NE.

The correction value h1 is the target rotation speed NT and the actual rotation speed.
When the difference from N2 is 50 rpm or less, it is set to zero and 5
It is set to a value of 3 to 10 in proportion to the difference between 0 and 200 rpm, and set to 10 when it is 200 rpm or more. Therefore, for example, when the target rotation speed NT is 650 rpm and the actual rotation speed NE is 600 rpm, the rate of change ΔNE is 9.375-3 = 6.375 (rpm / 32 msec) or more and the rotation speed NE is decreasing. , The time t2
The control duty is rapidly increased as indicated by.

Also, for example, when the target rotation speed NT is 800 rpm and the actual rotation speed NE is 600 rpm, the change rate ΔNE is 9.375−10 = −0.625 (rpm / 32 msec), so the rotation speed NE is in a substantially steady state. Even so,
A sudden increase in control duty is performed. That is, the farther the rotational speed NE is from the target rotational speed NT, the easier it is to execute the sudden increase control of the control duty.

On the other hand, by using the value KDPCa, at the time of pulsation of the rotation speed NE shown in FIG. 10, for example, when the change rate ΔNE changes from positive to negative, the change rate ΔNE is in the positive period.
W21, that is, the rotational speed NE is the threshold value L5 (NT-150 rpm) or more L
When the rate of change in the period W22 is small when the rate of change ΔNE is negative with respect to the value KDPCa updated in the period of 4 (NT + 100 rpm) or less, the abrupt control by the increment ΔD2 is abandoned.
This is because the control duty of the flow control valve 36 is changed as shown in FIG. 11 (2) in response to the fluctuation of the rotational speed NE shown in FIG. Although the control duty is in the vicinity of the value that should be stable due to the balance with the load, the rotational speed NE is
This is to prevent unnecessary fluctuation of the control duty as shown by the broken line in FIG. 11 (2) when the pulse is pulsating.

Further, the threshold value L1 which is another determination level is obtained by subtracting a correction value h2 determined corresponding to the difference between the actual rotation speed NE and the target rotation speed NT shown in FIG. 12 from a predetermined constant value. Will be asked for. That is, L1 = 9.375-h2 (6) The correction value h2 is the same as the correction value h1 and is the actual rotational speed NE.
When the difference between the target rotation speed NT and the target rotation speed NT is 50 rpm or less, it is set to zero, when it is 50 to 200 rpm, the difference is changed in the range of 3 to 10, and when it is 200 rpm or more, it is set to 10. It

That is, for example, when the target rotation speed NT is 700 rpm and the actual rotation speed NE is 750 rpm, the threshold value L1 is 6.37.
5 (rpm / 32 msec), and when the rate of change ΔNE of the rotation speed NE is equal to or greater than this threshold value L1, the control duty is rapidly reduced as shown from the time t7 onward.

In this way, the thresholds L1 and L2 are changed in accordance with the difference between the target rotation speed NT and the actual rotation speed NE, whereby the execution condition of the sudden increase / decrease control of the control duty is changed, The target rotation speed NT can be quickly converged.

On the other hand, the detection output of the intake pressure detector 23 used in the control calculation of the idle speed and the fuel injection amount is shown in FIG.
As shown by, the fluctuation occurs due to the opening / closing operation of the intake valve 9, and the fluctuation range is 50 to 100 mm at 4000 rpm, for example.
It is a large value of about Hg. In order to absorb this fluctuation and detect an accurate intake pressure, the detection output of the intake pressure detector 23 is subjected to filter processing in the control device 1.

Therefore, even if the flow rate control valve 36 is suddenly opened as shown in FIG. 13 (2) due to the delay due to the filter processing, the pressure waveform after the filter processing is the 13th.
In reference to the change in the pressure waveform of the actual intake pressure indicated by reference numeral 1 in FIG. (3), the reference numeral is delayed by time Δt2.
Appears as shown in l2.

Therefore, in FIG. 13 (3), the calculation timing t11
If the control duty is calculated based on the intake pressure at, the intake pressure that should originally be used to calculate the control duty will be reduced by the pressure difference ΔP2 corresponding to the filter processing time Δt2. Therefore, the pressure difference ΔP2 corresponding to the delay of the time Δt2 is predicted and calculated, and the calculation timing t1
Intake pressure in 1 needs to be corrected.

As shown in FIG. 13 (3), the pressure waveform l2 after the filtering process is almost equal to the pressure waveform 1 of the actual intake pressure, and therefore the time change rate dP / dt of the intake pressure P is accurately obtained. Therefore, it is possible to accurately correct such a delay.

The time change rate dP / dt is obtained as follows. That is, the intake air flow rate to the surge tank 6
And when the outflow air amount from the surge tank 6 is Qout, However, ΔQ is the amount of change in the intake air flow rate, and K1 is a constant. When the control duty of the flow rate control valve 36 is DUTY and the rotation speed of the internal combustion engine 10 is N, Qout = K3 · η · N · P (9) However, K2, K3 are constants, η is the intake efficiency, P _O
Is atmospheric pressure. Therefore, from the first equation, the intake pressure P after delay correction is However, Pi is the intake pressure at the above calculation timing, and K1
a = 1 / K1.

On the other hand, if the time between 180 ° CA is T, Becomes In this 11th formula, Δt2 is constant with respect to the time axis, and if this is set to B, That is, with regard to the delay due to the filter processing, by accurately obtaining ΔQ, these corrections can be obtained with generality and high precision.

Next, a method of calculating ΔQ / N will be described. The change in the intake air flow rate Qin when the flow rate control valve 36 suddenly opens is
It is as indicated by the reference numeral l3 in the figure. On the other hand, due to the influence of the surge tank 6 and the like, the outflow air flow rate Qout from the surge tank 6 is indicated by reference numeral l4. These flow rates Qin and Qout are shown by the above-mentioned formula 8 and formula 9, respectively.

During steady operation of the internal combustion engine 10, Qin = Qout and the flow rate Qin
Is the control duty of the flow control valve 36 and the intake pressure P.
Is used as a parameter and the flow rate Qout in the steady state is measured and obtained in advance. That is, the value corresponding to N · P in the above equation 9 is the control duty as shown in FIG.
A product value MAP of N and P in each control duty DUTY when the intake pressure P is changed while keeping DUTY constant is used. As a result, the flow rate Qin can be expressed as in Expression 13. The graph shown in FIG.
Stored as a map in 45.

Qin ＝ K3 ・ η ・ MAP… (13) It can be expressed as.

However, in the 14th equation, MAP / N and P _M are due to variations in manufacturing of the internal combustion engine 10, aging, etc.
During actual control, the values may not match in the steady state. Therefore, in this embodiment, the intake pressure P _M is used by replacing it with the value P c calculated. Even if the intake pressure P _M is deviated due to such variations as described above, the rate of change over time
dP / dt is almost the same, and therefore, similar to the delay correction described above by the tenth equation, It can be expressed as. However, Pci is the calculated value of this time, and Pci _-1 is the calculated value of the previous time. Therefore, MAP / N
, And the calculated value Pc always coincides with the steady state, and during the transition, the MAP / N changes abruptly with the change of the control duty DUTY, and the value Pc changes following so as to coincide with it. Therefore, the value Pc is successively calculated based on the 16th equation, for example, every 4 msec.

However, K5 = K1a · K3 · η.

As described above, the correction value Pc was obtained in consideration of the delay due to the filter process and the variation of the internal combustion engine 10. However, when the delay is small or when the control is desired to be simpler, the value Pc is used instead. It is also possible to control using the actual intake pressure P _M. It was but connexion, what is described in Pc in the following description, the case of substitute P _M is assumed to replace the P _M.

Further, for the internal combustion engine 10, when the calculated value Pc of the intake pressure obtained as described above is used, for example, when the control duty of the flow control valve 16 is increased, the value Pc increases corresponding to the increase. Therefore, there is a considerable response delay until the generated torque actually increases and the rotation speed NE increases.

Therefore, in the present embodiment, in response to the response delay, the value Pc obtained as described above is further subjected to the delay processing shown in the seventeenth equation to correspond to the actual response characteristic of the internal combustion engine 10. Obtain the calculated value PcFa of the intake pressure.

However, PcFO is the calculated value of the previous PcFa, and h3 is a constant and is selected to be 4, for example.

The smaller of this value PcFa and the value Pc is the delayed inspiratory pressure PcF.
Then, the control duty calculation of the flow rate control valve 36 is performed using the delayed intake pressure PcF. That is, when the values Pc and PcFa are indicated by reference signs l5 and l6 in FIG. 16, respectively, the delayed intake pressure PcF is a value indicated by reference sign l7. This delayed inspiratory pressure P
By using cF, the control duty can be stably converged after the abrupt control shown at the times t2 and t5 is performed.

17 to 20 are flow charts for explaining the above-described idle rotation speed control operation. FIG. 17 shows an operation for obtaining the rotational speed NE of the internal combustion engine 10. This operation is performed at a timing with a small error due to a stroke difference between the cylinders of the internal combustion engine 10, for example, every 180 ° CA when there are four cylinders. Be seen. In step s1, the rotational speed NE is measured by the crank angle detector 27, and in step s2, the time change rate ΔNE is calculated from the measurement result in step s1 and the previous measurement result, and then the other operation is performed. Move.

FIG. 18 shows the operation for obtaining the intake pressure P _M , and the step
In s11, the measurement result of the intake pressure detector 23 is digitally converted by the analog / digital converter 42 and read into the processing circuit 43. This operation is performed, for example, every time a conversion operation is performed every 2 msec.

FIG. 19 is a flow chart for explaining the correction calculation shown in the above-mentioned Expression 16, for example, an analog signal of the throttle valve opening θ detected by the throttle valve opening detector 22 every 4 msec. It is performed for each digital conversion operation. At step s21, the throttle valve opening θ is read,
In step s22, from the throttle valve opening θ obtained in step s21 and the value Pc obtained in step s30 described later, the map value MA is calculated based on the graph shown in FIG.
P is read.

In step s23, the value MAP and the rotational speed NE are divided,
In step s24, the value Pc is subtracted from the division result. At step s25, the sign for the approximation operation of the value Pc at step s30 described later is set according to whether the result of the subtraction at step s24 is positive or negative. In step s26, it is judged whether or not the set sign is positive, and if not, in step s27, the absolute value of the subtraction result in the step s24 is calculated and then the process proceeds to step s28, and if so, Go directly to step s28.

At step s28, the subtraction result at step s24 is multiplied by the rotation speed NE. In step s29, the above value K5
Is multiplied by the calculation result obtained in step s28, and the value Pc is updated in step s30 based on the code set in step s25 using this multiplication result. In this way, the approximate calculation of the value Pc shown in the 16th equation is performed. As described above, when the actual intake pressure P _M is used instead of the value Pc, the operation shown in FIG. 19 is unnecessary.

FIG. 20 is a flow chart for explaining the duty control operation of the flow rate control valve 36 for controlling the idle rotation speed. At step n1, it is determined whether the internal combustion engine 10 is stopped, and if so, step n2
Then, the control duty DUTY of the flow rate control valve 36 is set to 0%, and the actual intake pressure P _M is set as the initial value of the value PcFa at step n2a.
If is being driven, the process proceeds to step n3.

At step n3, whether or not a change in the rotational speed NE between 180 ° CA can be detected, that is, at the steps s1 and s
It is determined whether or not the predetermined operation timing is reached when the operation of 2 is completed, and if not, the process moves to step n41, and if so, to step n4.

In step n4, the arithmetic processing shown by the first equation is performed based on the time T180 required for the internal combustion engine 10 to rotate by 180 ° CA. At steps n5, n6, and n7, the arithmetic processings shown by the second, third, and fourth equations are performed, respectively, and thus the advance rotational speed NEADV is obtained at steps n4 to n7.

In step n7a, the value obtained in step s30
The value PcFa is calculated from Pc based on the above-mentioned expression 17. At step n8, the idle speed increment determined in accordance with the cooling water temperature detected by the cooling water temperature detector 24.
NTADD1 is required.

At step n9, it is determined whether or not a predetermined time, for example, 2 seconds has elapsed since the internal combustion engine 10 was started by the starter motor 33 and started, and if not, at step n10, the idle speed The increment NTADD2 is moved to step n11 after being set to, for example, 300 rpm and, if so, directly to step n11. This increment NTADD
2 is a value for promptly supplying the lubricating oil to each part of the internal combustion engine 10, and as shown in steps n42 to n44 described later, decreases with the passage of time after the passage of 2 seconds. Being done.

In step n11, the air conditioning detector 30 and the neutral detector 3
The basic idle rotation speed NTBASE is required according to the detection result of 1 and the usage status of the electric load. In step n12, the basic idle speed NTBASE is incremented by N
The target rotation speed NT is obtained by adding TADD1 and NTADD2. However, at this time, the maximum value of the target rotation speed NT is 1250.
Set to rpm.

At step n13, it is judged based on the output of the start detector 29 whether or not the starter motor 33 is being started, and if so, at step n14,
The control duty DUTY is set to the control duty DSTART at the time of start, which is determined corresponding to the cooling water temperature, and then the process proceeds to step n15. When the engine is not started at step n13, the routine proceeds to step n16, where it is judged whether or not the throttle valve 5 is in the idle state in which the throttle valve 5 is fully closed. If not, at step n15, the sudden control flag FPCS described later becomes zero. After reset, move to step n41,
If so, move to step n17.

In step n17, the value P obtained in steps s21 to s30 is calculated.
c, it is determined which of the value PcFa obtained based on the 17th equation in step n7a using the value Pc is larger,
The smaller value of step n18 or n19 is the delayed inspiratory pressure PcF.
Is set to step n21.

In step n21, it is judged whether or not the time change rate ΔNE obtained in step s2 is less than or equal to the threshold value L2 shown in the fifth equation, and if so, that is, the rotation speed NE.
Is decreasing, the process proceeds to step n22, where it is determined whether or not the rotational speed NE is equal to or higher than the threshold value L4. If not, that is, the control duty DUTY is rapidly increased at the time t2. If necessary, move to step n23. In step n23, the sudden control flag FP
A flag FPSML, which is provided corresponding to CS and indicates whether the increase control or the decrease control needs to be performed, is set to 1 to indicate that the increase control needs to be performed, and the process proceeds to step n31.

When the rate of change ΔNE is larger than the threshold value L2 in the step n21, and in the step n22, the rotation speed NE is
Is higher than the threshold value L4, that is, when it is not necessary to control the sudden increase of the control duty, step n25
Move on to. In step n25, it is judged whether or not the change rate ΔNE is equal to or more than the threshold value L1 shown in the above equation 6, and if so, that is, when the rotational speed NE is increasing, in step n26 the rotational speed NE is It is determined whether or not the threshold value is less than or equal to the threshold value L3. If not, that is, when it is necessary to perform the rapid decrease control, the process proceeds to step n27. In step n27, the flag FPSML is reset to 0 and the process proceeds to step n31.

At step n31, the abrupt control flag FPCS is set to 1, which means that the control duty is being abruptly increased or decreased.

In step n32, the control duty until then,
Based on the time change rate ΔNE of the rotational speed NE, the increment ΔD2 obtained from FIG. 7 is added to obtain the control duty DUTY.
Will be updated. At step n33, this updated control duty DUTY is limited to within the range of 10-90%. This operation is performed so that the control duty DUTY is accurately controlled by the flow control valve 36, that is, within the range in which the correct operation of the flow control valve 36 can be guaranteed.

In step n34, it is determined whether or not the rotation speed NE is increasing, and if so, it is determined in step n35 whether or not the rotation speed NE is equal to or more than the threshold value L5 and less than or equal to L4. At some point, move to step n36. Step n
At 36, the value KDPCa is updated by the rate of change ΔNE, as indicated by the period W21 in FIG.
Go to 41. Further, in step n34, the rotation speed NE
Is not rising, and when the rotation speed NE is out of the range of the threshold value L5 or more and L4 or less in step n35, the process directly proceeds to step n41.

At step n41, the control duty at the time of abrupt increase / decrease control obtained at steps n32, 33, or the control duty at the time of integral control obtained at steps n55, n33 described later, or at steps n62 to n64 described later is obtained. Flow control valve 36 based on the control duty during return control
Is duty controlled.

In step n42, it is determined whether or not a predetermined time, for example, 1 second has elapsed. If not, the operation is ended, and if so, the process proceeds to step n43. In step n43, it is judged whether or not the increment NTADD2 is 0, and if so, the operation is ended. Otherwise, in step n44, the increment NTADD2 is subtracted by 10 rpm and updated, and then the operation is performed. finish.

When the rate of change ΔNE is less than the threshold L1 at the step n25 and at the step n26, the rotation speed NE is at the threshold L.
When it is higher than 3, that is, when the abrupt control as described above is not performed, the process proceeds to step n50. At step n50, the rotation speed NE is a value that is predetermined from the target rotation speed NT, for example,
It is determined whether or not the threshold value is equal to or lower than the threshold value L6 lower by 200 rpm, and if so, that is, if the engine is in a very stalled state, the process proceeds to step n51, and if not, the process proceeds to step n52.

At step n51, it is judged whether or not the sudden control flag FPCS is 1, and if so, that is, the control duty DU
Immediately after the rapid increase / decrease control of TY is performed, the process proceeds to step n61. At step n61, the target rotation speed
The target value α of the intake air flow rate, which is a parameter related to the torque of the internal combustion engine 10, is set from the product value of NT and the delayed intake pressure PcF. At step n62, a predetermined increment ΔD3 is added to or subtracted from the control duty DUTY. That is, when the flag FPSML is 0, the increment ΔD3 is added,
When it is 1, the increment ΔD3 is subtracted.

In step n63, the value MAP is read from the graph shown in FIG. 15 based on the control duty DUTY and the delayed intake pressure PcF updated in step n62, and this value MAP is set in step n61. It is determined whether or not the target value α is approximately equal. If not, these steps n62,
Repeat n63, and when it becomes almost equal to the target value α,
Move to step n64.

At step n64, the control duty at the time of the return control obtained as described above is updated by adding the increment ΔD4. In step n65, the abrupt control flag FPCS is reset to 0, and then the process proceeds to step n34.

The flag FPSML is set to 1 at step n52, and the rapid control flag FPCS is set to 1 at step n53. After the increment ΔD2 is set to 50% in step n54, the operation after step n32 is started, and the control duty D
A sudden increase control of UTY is performed, thus preventing stalling.

When the abrupt control flag FPCS is not 1 in step n51, that is, after the return control shown in steps n61 to n65 has been performed, the process proceeds to step n55, and the advance angle rotational speed obtained in steps n4 to n7. NEADV,
Corresponding to the difference from the target rotational speed NT, the increment ΔD1 is read out based on the graph shown in FIG. 6 and the control duty DUTY is updated. Then, the routine proceeds to step n33, where the integral control is performed.

As described above, in the control device 1 according to the present invention, when a sudden drop in the rotational speed NE due to a load change is detected, the control duty DUTY of the flow control valve 36 is increased by an increment ΔD2 corresponding to the change rate ΔNE of the rotational speed NE. Change only and suppress the drop promptly. When the drop in the rotational speed NE subsides,
The control duty DUTY corresponding to the target value α of the intake air flow rate at that time is rapidly decreased by a predetermined increment ΔD3, and then the increment ΔD4 is added. Therefore, it is possible to secure good stability with a large control gain and without excessive control that causes a blow-up, and also to reliably prevent engine stall during return control by the increment ΔD3. You can

Also, when the rotational speed NE increases due to load fluctuation, similarly, it is possible to quickly suppress blow-up, etc. and reliably prevent engine stall due to overcontrol, thus providing both responsiveness and stability. Idle rotation speed control can be performed.

Furthermore, thresholds L3 and L4 are provided near the target rotation speed NT, and the abrupt control by the increment ΔD2 is performed at the measured rotation speed.
If the NE is higher than the threshold L3 during rising, the threshold is falling during falling
Since it is executed when it is less than L4, unnecessary control can be prevented, and thereby stability can be further improved.

Further, by the step n52, when the rotation speed NE is stopped below the threshold value L6 and it is very easy to stall, and when the rotation speed further decreases, the control duty is unconditionally changed at steps n54, n32, n33. Since it is increased by 50%, the engine stall can be surely prevented also by this.

Furthermore, since the thresholds L1 and L2, which are the determination levels for executing the sudden control, are changed corresponding to the rotation speed NE and the difference between the rotation speed NE and the target rotation speed NT, the difference is large. At the same time, it is possible to quickly converge to the target rotation speed NT, prevent unnecessary control at high rotation speed where the rotation speed NE is stable, and reduce slightly when the rotation speed NE is not stable at low rotation speed. It is possible to detect various fluctuations sensitively and prevent engine stall reliably.

Further, by improving the responsiveness to load fluctuations in this way, various device outputs to be taken into the control device 1, measurement results of sensors, etc. can be minimized,
As a result, the structure can be simplified.

As described above, according to the present invention, when the internal combustion engine is idle, the determination level is set according to the rotation speed or the difference between the rotation speed and the target rotation speed, and the time change rate of the rotation speed is When the rotation speed is exceeded, the fluctuation of the rotation speed is detected, and the control amount of the flow control valve for idle is changed rapidly at a relatively large change rate. The intake air flow rate can be increased with a relatively large time change rate to prevent engine stalling. Further, when the time rate of change of the rotational speed becomes close to zero, the target value of the parameter related to the torque of the internal combustion engine at that time is set, and the target value is maintained or abruptly changed to a value that can be changed gently. In addition, the control amount of the flow control valve is reduced, and the rising of air due to overcontrol is prevented.

Further, when the rotation speed is low and unstable, a slight change in the rotation speed can be detected sensitively, and a control with good responsiveness can be performed with a high control gain.

On the other hand, when the rotation speed is high and stable, unnecessary control operation is prevented and stability can be improved.
Furthermore, even if the target rotation speed is changed and the rotation speed is far from the target rotation speed, the target rotation speed can be quickly converged.

In addition, the number of loads output from various devices and sensors that are loads can be reduced, and the configuration can be simplified.

[Brief description of drawings]

FIG. 1 is a block diagram showing a control device 1 of an internal combustion engine according to an embodiment of the present invention and a configuration related thereto, FIG. 2 is a block diagram showing a concrete configuration of the control device 1, and FIG. 4 is a timing chart for explaining the idle rotation speed control operation, FIG. 4 is a timing chart for explaining the integral control operation, and FIG. 5 is a rotation speed NE and a target rotation speed.
Graph showing the change in advance time TADV corresponding to the difference with NT,
FIG. 6 is a graph showing changes in the increment ΔD1 during integral control, FIG. 7 is a graph showing changes in the increment ΔD2 during sudden control, and FIG. 8 is a graph showing changes in the value KDPC with respect to the rotational speed NE. Fig. 10 is a graph showing changes in the correction value h1 corresponding to the difference between the target rotation speed NT and the rotation speed NE. Fig. 10 shows the value KDPC.
FIG. 11 is a graph showing the change of the rotational speed NE for explaining the updating operation of a, FIG. 11 is a timing chart for explaining the erroneous control prevention operation for the vibration of the internal combustion engine 10, and FIG. 12 is the rotational speed NE and the target. Fig. 13 is a graph showing the change in the correction value h2 with respect to the difference from the rotation speed NT, Fig. 13 is a timing chart for explaining the operation during a transition when the control duty DUTY is changed, and Fig. 14 is the intake air to the surge tank 6. Flow rate Qi
Fig. 15 is a graph showing the relationship between n and the outflow air flow rate Qout, Fig. 15 is a graph showing changes in the value MAP with respect to changes in the intake pressures P, Pc, PcF in each control duty DUTY, and Fig. 16 is the internal combustion engine 10
FIG. 17 to FIG. 20 are graphs showing changes in the delayed intake pressure PcF in consideration of the response delay of the torque generated by the engine, and FIGS. 17 to 20 are flow charts for explaining the idle speed control operation. 1 ... Control device, 4, 7 ... Intake pipe, 5 ... Slot valve, 6 ...
Surge tank, 8 ... Fuel injection valve, 10 ... Internal combustion engine, 14 ... Exhaust pipe, 20-31 ... Detector, 35 ... Bypass, 36 ... Flow control valve, 43
… Processing circuit, 45… Memory

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-59-110843 (JP, A) JP-A-54-96628 (JP, A) JP-A-56-116119 (JP, A) JP-A-61- 223246 (JP, A) JP-A-60-19934 (JP, A)

Claims (6)

[Claims] 1. A rotational speed of an internal combustion engine is provided by connecting an upstream side and a downstream side of a throttle valve with an bypass bypass passage for idle, and changing a control amount of a flow control valve provided in the bypass passage. In an idle speed control device for an internal combustion engine that maintains a predetermined target rotation speed, a determination level is set according to the rotation speed, and a time change rate of the rotation speed is relatively lower than the determination level. The control amount is rapidly increased with a large rate of change, and when the time rate of change of the rotational speed becomes zero or almost zero, the target value of the parameter related to the torque of the internal combustion engine at that time is set, An idle speed control device for an internal combustion engine, characterized in that the control amount is rapidly reduced to a value at which a target value can be maintained or gently changed. 2. A rotational speed of an internal combustion engine is provided by connecting an upstream side and a downstream side of a throttle valve by an bypass bypass passage for idling and changing a control amount of a flow control valve provided in the bypass passage. In an idle speed control device for an internal combustion engine that maintains a predetermined target rotation speed, a determination level is set according to the rotation speed, and a time change rate of the rotation speed is relatively higher than the determination level. The control amount is rapidly reduced with a large change rate, and when the time change rate of the rotational speed becomes zero or almost zero, the target value of the parameter related to the torque of the internal combustion engine at that time is set, An idle speed control device for an internal combustion engine, characterized in that the control amount is rapidly increased to a value at which a target value can be maintained or gently changed. 3. A rotational speed of an internal combustion engine is provided by connecting an upstream side and a downstream side of a throttle valve by an bypass bypass passage for idling and changing a control amount of a flow control valve provided in the bypass passage. In an idle speed control device for an internal combustion engine that maintains a predetermined target rotation speed, a determination level is set according to the difference between the rotation speed and the target rotation speed, and the time change rate of the rotation speed is equal to or lower than the determination level. The control amount is rapidly increased with a relatively large change rate, and at the time when the time change rate of the rotation speed becomes zero or almost zero, the parameter related to the torque of the internal combustion engine at that time is changed. An idle speed control device for an internal combustion engine, wherein a target value is set, and the control amount is rapidly reduced to a value at which the target value can be maintained or gently changed. 4. A rotational speed of an internal combustion engine is provided by connecting an upstream side and a downstream side of a throttle valve by an bypass bypass passage for idling, and changing a control amount of a flow control valve provided in the bypass passage. In an idle speed control device for an internal combustion engine that maintains a predetermined target rotation speed, a determination level is set according to the difference between the rotation speed and the target rotation speed, and the time change rate of the rotation speed is equal to or higher than the determination level. Then, the control amount is rapidly reduced with a relatively large change rate, and when the time change rate of the rotational speed becomes zero or almost zero, the parameter related to the torque of the internal combustion engine at that time is changed. An idle speed control device for an internal combustion engine, wherein a target value is set, and the control amount is rapidly increased to a value that can maintain or gently change the target value. 5. The internal combustion engine according to claim 1, wherein the parameter is a value related to an intake pipe pressure or a product value of the intake pipe pressure and a rotation speed. Idling speed control device. 6. The idle speed of an internal combustion engine according to claim 5, wherein the intake pipe pressure is determined in consideration of a response delay of the torque generated by the internal combustion engine with respect to a change in the control amount of the flow control valve. Control device.