JPH0364639A - Idle rotation frequency control device of internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent an engine stop by converting the control amount of a flow control valve for idling, and converting suddenly the control amount of the flow control valve when the time variation rate of the rotation speed comes close to zero, at the time when a variation of the rotation speed is detected in an idling operation. CONSTITUTION:A flow control valve 36 is provided to a side passage 35 connected to a suction pipe 4 which detours a throttle valve 5, and by duty- controlling the flow control valve 36 with a control device 1, the engine rotation speed is maintained at the object rotation speed. In this case, in the control device 1, a drop or a rise of the rotation speed calculated depending on the output of a crank angle detector 27 is detected, and responding to the time variation rate of the drop or the rise, the control amount to be given to the flow control valve 36 is increased or decreased in a relatively large time variation rate. And at the time when the time variation rate of the rotation speed comes to zero or about zero, a parameter related to the engine torque is set, and the control amount is to be decreased or increased suddenly up to the value to maintain the set value.

Description

[Detailed Description of the Invention] Overview When a fluctuation in the rotational speed is detected when the internal combustion engine is idling, the flow rate provided in the bypass side passage for idling is increased at a relatively large rate of change in accordance with the time rate of change of the fluctuation. Change the control amount of the control valve.

As a result, when the time rate of change of the rotational speed approaches zero rt, parameters related to the torque of the internal combustion engine are set for that point, and the set value is maintained or rapidly changed to a value that can be changed gradually. The control amount of the flow control valve is changed.

Therefore, for example, when the rotational speed drops, the intake air flow rate is increased at a relatively large rate of change over time, making it possible to prevent engine stalling. Furthermore, when the time rate of change in rotational speed begins to rise after reaching the minimum value, the intake air flow rate is rapidly reduced to a value that can maintain the torque at that point, preventing so-called blow-up due to overcontrol. . In this way, idle rotation speed control with high control gain and good stability is performed.

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

In conventional internal combustion engines, when the engine is idling and the generated torque is small, the rotational speed fluctuates due to slight load fluctuations. For example, the rotational speed decreases when a power load such as an audio device or an air conditioner starts to be used, when the power steering is turned off, or when the automatic transmission is placed in the D range.

On the other hand, in recent years, the idle speed has been kept relatively low in order to improve fuel efficiency, and therefore P4. i, there is a risk of engine stalling.

For this reason, in typical conventional technology, the control device that controls the flow rate control valve installed in the idle bypass side path incorporates the outputs of various devices that cause load fluctuations, the detection results of sensors, etc. When the cooler is in use, the idle speed is controlled such that the idle speed is increased by 250 rpm. In addition, a predetermined control amount is added to each load etc. so that the rotation speed set in this way is achieved, and integral control is performed with a small control gain to suppress overcontrol.

Problems to be Solved by the Invention In the conventional technology as described above, the control device needs to receive outputs from various devices, detection results of sensors, etc.
The configuration becomes complicated and costs increase, and the control gain is low, resulting in poor responsiveness and a long time required to reach the target rotational speed. On the other hand, when this control gain is increased, responsiveness improves, but stability deteriorates. That is, excessive control occurs, resulting in overcontrol, which leads to undesirable situations such as so-called blow-up.

An object of the present invention is to provide an idle rotation speed control device for an internal combustion engine that can simplify the configuration and achieve both responsiveness and stability.

Means for Solving the Problems The present invention communicates the upstream side and the downstream side of the throttle valve with an idle bypass side passage, and changes the control amount of a flow control valve provided in the side passage, thereby reducing internal combustion. In an idle rotation speed control device for an internal combustion engine that maintains the rotation speed of the engine at a predetermined target rotation speed, a drop/rise in the rotation speed is detected, and a relatively The control amount is increased/decreased at a large rate of change, and when the rate of change over time of the rotational speed becomes zero or almost zero, a parameter related to the torque of the internal combustion engine at that point is set, and the parameter is set. The idle rotation speed control device for an internal combustion engine is characterized in that the control amount is rapidly decreased/increased to a value that can maintain a value or change smoothly.

Further, in the present invention, the increase/decrease control of the control amount by detecting a drop or increase in the rotational speed is such that when the rotational speed drops, the rotational speed is near the target rotational speed and is higher than the target rotational speed in advance. The rotation speed is executed when the rotation speed is lower than a predetermined first value, and when the rotation speed increases, the rotation speed is executed when the rotation speed is near the target rotation speed and higher than a predetermined second value that is lower than the target rotation speed. This is an idle rotation speed control device for an internal combustion engine.

Furthermore, the present invention provides an idle rotation speed control device for an internal combustion engine, wherein the parameter is an intake pipe pressure.

According to the present invention, when a relatively large fluctuation in the rotational speed is detected when the internal combustion engine is idling, the engine is installed in the idling bypass side passage at a relatively large rate of change depending on the time rate of change of the fluctuation. The amount of control of the flow 1 control valve is changed. As a result, when the time rate of change of the rotational speed approaches zero, parameters related to internal combustion engine torque, such as intake pipe pressure, are set at that point, and the set value is maintained or gradually reduced. The control amount of the flow control valve is suddenly changed to a value that can be changed.

Therefore, for example, when the rotational speed drops, the intake air flow rate is increased at a relatively large rate of change over time, making it possible to prevent engine stalling. Further, when the time rate of change of the rotational speed starts to increase after passing through the minimum value, the intake air flow rate is rapidly reduced to a value that can maintain the torque at that point, and so-called blow-up is prevented. In this way, idle rotational speed control with high control gain and good stability is performed.

Embodiment FIG. 1 shows a control device 1 for an internal combustion engine according to an embodiment of the present invention.
FIG. 2 is a block diagram showing a configuration related to the configuration. Combustion air introduced from the intake port 2 is purified by an air cleaner, passes through an intake pipe 4, and after adjusting its inflow amount with a throttle valve 5 interposed in the intake pipe 4, it is sent to a surge tank 6. Inflow.

Combustion air flowing out of the surge tank 6 is mixed with fuel injected from a fuel injection valve 8 disposed in an intake pipe 7 , and is 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 into the atmosphere from an exhaust pipe 14 via 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 connection with the throttle valve 5, and a surge tank 6 is provided with a throttle valve opening degree detector 22.
An intake pressure detector 23 for detecting the pressure in the intake pipe 7 is provided. Further, 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 an oxygen concentration detector 25 is provided downstream of the three-way catalyst 15. An exhaust temperature detector 26 is provided.

The rotational speed of the internal combustion engine 10, that is, the number of rotations per unit time, is detected by the crank angle detector 27.

The win device 1 includes each of the detectors 21 to 27,
A vehicle speed detector 28, a start detector 29 that detects whether the starter motor 33 that starts the internal combustion engine 10 is activated, an air conditioning detector 30 that detects the use of the air conditioner, etc. When the vehicle equipped with an automatic transmission is equipped with an automatic transmission, a detection result from a neutral detector 31 that detects whether the gear position of the automatic transmission is in the neutral position is input.

Furthermore, the control device 1 is powered by a battery 34, and the suppression device 1 is connected to each of the detectors 21 to 34.
31 and the power supply voltage of the battery 34 detected by the voltage detector 20, the fuel injection amount, ignition timing, etc. are calculated, and the fuel injection valve 8, the spark plug 12, etc. are controlled.

The intake pipe 4 is also formed with a side passage 35 that bypasses the upstream and downstream sides of the throttle valve 5, and a flow rate rfII control valve 3 36 is provided in this side passage 35. The flow rate l1iIJ control valve 36 is configured using, for example, a diaphragm, and the control device 1 performs duty control on a vacuum switching valve that introduces negative intake pressure into the diaphragm chamber, so that the throttle valve 5 is almost fully closed during idle. Adjust and control the flow rate of combustion air at the time.

The l1ffi device 1 also drives the fuel pump 32 when the internal combustion engine 10 is operating.

FIG. 2 is a block diagram showing one specific commandment of the control device 1. The detection results of the detectors 20 to 25 are supplied from an input ink face circuit 41 to a processing circuit 43 via an analog/digital converter 42.
The detection results of 2.27 to 31 are provided to the processing circuit 43 via the input ink face 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 is provided with a memory 45 for storing various control maps and learning values. Supplied via.

The control output from the processing circuit 43 is derived via an output interface circuit 47, is applied to the fuel injection valve 8 to control the fuel injection amount, and is also applied to the spark plug 12 via the igniter 48 to spark the ignition. The timing is controlled, which is also applied to the flow control valve 36 to control the flow rate of incoming air through the side passage 35 during idle, and to drive the fuel cylinder 132.

The detection result of the exhaust gas 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 temperature, the warning light 5 is turned on via the drive circuit 50.
1 is lit.

FIG. 3 is a timing chart for explaining the operation of the control device Ill configured as described above. 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 the actual rotational speed N.
Based on the difference between E and target rotational speed NT, integral control is performed in relatively small increments ΔD1, as shown in FIG. 3 (4).

As shown in FIG. 4, the increment ΔD1 of this integral control is the difference between the actual rotational speed NE and the target rotational speed NT.
For example, when it is within the dead zone of NT±15 rpm, it is set to zero, and outside the dead zone, it is set to a value corresponding to the difference NE-NT. In this way, during steady state, the rotational speed NE is controlled to fall within the dead zone.

The target rotational speed NT is, for example, 700 at no load.
RP theory and is set to 950 rpm when the air conditioner is used.

As shown in FIG. 3(1) at time tl, when the gear stage of the automatic transmission is switched from the neutral position to the drive position by the neutral detector 31, the internal combustion engine 1
0 increases, and the rotational speed NE starts to drop as shown in FIG. 3 (2>).

Due to this drop, when the rate of change ΔNE of the rotational speed NE per unit time becomes equal to or less than the predetermined threshold L2 as shown in FIG. As shown in FIG. 3 (5>), a relatively large increment ΔD2 corresponding to the rate of change ΔNH is added to the control duty of the flow rate control valve 36, thereby increasing the intake pressure P of the surge tank 6, as shown in FIG. 3 (5>). , rises rapidly.

Note that the relationship between the rate of change ΔNE and the increment ΔD2 is based on the fifth
As shown in the figure, when it is larger than one threshold L2 smaller than zero and less than the other threshold L1 larger than zero, it is set to the dead zone W2 of ΔD2=o. Further, when the rate of change ΔNE is less than or equal to the threshold L2, and L
When it is 1 or more, the increment ΔD2 is set corresponding to the rate of change ΔNE. The graph shown in FIG. 5 and the graph shown in FIG. 4 are stored in advance as a map in the memory 45.

The drop in rotational speed NE is suppressed by the increase in the intake pressure Pi, and the rate of change ΔNE reaches the minimum value at time t3,
At time t4, as shown in FIG. 3(3), when the rate of change ΔNE exceeds the threshold L2 and enters the dead zone W2 again, the intake pressures P, I decrease as shown in FIG. 3(4). The time rate of change ΔP, l (Fig. 3 (6〉〉) becomes almost zero (
Until time t4a>, the control duty is repeatedly subtracted by a predetermined value ΔD3 and rapidly decreased. This allows the internal combustion engine 10 to respond to changes in control duty.
Prevents excessive control due to delayed response of generated torque.

However, even with this control, in case 1 where the rotational speed NE does not stabilize well and shows an increase, the rate of change ΔNE reaches the threshold value I as shown at time t5.

When it becomes 1 or more, the control duty is subtracted by an increment ΔD2 corresponding to the rate of change ΔNE, as shown in FIG. 5. In this way, the rate of change ΔNE enters the dead zone W2 and stabilizes, and when the time rate of change ΔPH of the intake pressure P7 becomes almost zero as shown in Fig. 3 (6>), from that time t6, the actual rotational speed NE and The integral control is performed in accordance with the difference from the target rotational distance NT.

Further, as shown from time 1Jit7 onwards, when the gear stage of the automatic transmission is switched to the neutral position,
The rotational speed NE increases and is quickly stabilized by a similar operation.

6 to 8 are flowcharts for explaining the above-mentioned idle rotation speed control operation.

FIG. 6 shows an operation for determining the rotational speed NE of the internal combustion engine 10, and this operation is performed, for example, every 180 degrees of crank angle (hereinafter referred to as CA).

In step S1', the rotation speed NE is measured by the crank angle detector 27, and in step S2, the time rate of change ΔNE is calculated from the measurement result in step S1 and the previous measurement result. In step S3, a flag FNE indicating that the rotational speed NE has been measured is set to 1, and the process moves on to other operations.

FIG. 7 shows the operation for determining the intake pressure P, and this operation is performed, for example, every 2IIISec, when the intake pressure PH detected by the intake pressure detector 23 is converted into digital by the analog/digital converter 42. It is done every. In step sll, 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. In step S12, the rate of change ΔP9 of the intake pressure is calculated based on the measurement result in step all and the previous measurement result. Step S13
Now, the intake pressure P. The flag FF indicating that the measurement process has been performed is set to 1, and the process moves on to other operations.

FIG. 8 is a flowchart for explaining the duty control operation of the flow rate control valve 36 for controlling the idle rotation speed. In step S21, it is determined whether or not the flag FNE is 1. If so, that is, when the rotational speed NE measurement process is completed and a predetermined calculation timing has arrived, the process moves to step S22. Step S
In step S22, it is determined from the measurement result in step S2 whether the rate of change ΔNE is greater than or equal to the threshold value L1, and if so, that is, if the rotational speed NE is increasing, the process moves to step S23.

In step 523, it is determined whether or not the rotational speed NE measured in step S1 is less than or equal to a threshold value of 3, which is 50 rpm lower than the target rotational speed NT. If there is, in step S24, a flag FΔN3 indicating a change in rotational speed is set.
After setting 1 to indicate that the rotational speed NE is increasing, the process moves to step S25.

Further, in step S22, when the rate of change ΔNE is less than the threshold 1, the process moves to step S26, where it is determined whether the rate of change ΔNE is less than the threshold 2, and if so, that is, the rotational speed NE decreases. If it is inside, the process moves to step S27. In step S27, it is determined whether or not the rotational speed NE is a threshold value higher than the target rotational speed NT by l OQ rpm, which is 4 or more. If not, that is, if the control is to be executed, step S28 is performed. , after resetting the flag FΔN3 to zero to indicate that the rotational speed NE is decreasing,
The process moves to step S25.

In step S25, the corresponding increment ΔD2 is read from the graph shown in FIG. 5 based on the time rate of change ΔNE, and the control duty DUTY is updated by adding this increment ΔD2. In this way, sudden control as shown at time t2 is performed, and the sudden control flag FΔN1 representing this is set to 1 in step S29, and the dead zone flag FΔN2 is reset to zero in step S30, indicating that the control is outside the dead zone. , and the process moves to step S31.

Further, when it is determined in step S23 and step S27 that the situation is such that sudden control should not be executed, and through step 522s26, the rate of change Δ
When it is determined that NE is within the dead zone W2, the dead zone flag FΔN2 is set to 1 in step S50, and then the process moves to step 931.

In step s31, a flag FNE indicating that the rotational speed NE has been measured is reset to zero. In step s32, it is determined whether or not the sudden control flag FΔN1 is 1. If not, that is, if it is not immediately after performing sudden control, then in step s33, the actual rotational speed NE and the target rotational speed NT are determined. Based on the difference,
The increment ΔD1 is read from the graph shown in FIG. 4, the control duty DUTY is updated by this increment ΔD1, and gentle integral control is performed, and step s34
Move to.

Further, when the flag FNE is not 1 in step s21, that is, after the rotational speed NE measurement process has been performed, and when the operations shown in steps s22 to s33 have already been completed, and in step s32, the sudden control flag When FΔN1 is 1, that is, the step s
When the abrupt control in step S25 is performed, the process moves directly to step S34.

In step s34, it is determined whether the sudden control flag FΔN1 is 1, and if so, step s
In step s35, it is determined whether the dead zone flag FΔN2 is 1, and if so, in step s36, it is determined whether the flag FF, which indicates that the measurement process of the intake pressure P9 has been performed, is 1. If so, step s37
Move to.

That is, after sudden control is performed by performing steps s34 to s36, the process enters the dead zone W2 and moves to step s37 at a calculation timing that coincides with the measurement timing of the intake pressure PM.

In step s37, the intake pressure P. It is determined whether or not the time rate of change ΔP is approximately zero, and if so, the sudden control flag FΔN1 is reset to zero in step s38, and then the process moves to step s39, and if not, the process moves directly to step s39.

In step s39, the step 524t or s28
A predetermined increment ΔD3 is added or subtracted from the control duty DUTY in accordance with the flag FΔN3 set in . That is, when the flag FΔN3 is 1, the increment Δ
D3 is added, and when the flag FΔN3 is zero, the increment Δ
D3 is subtracted, and the control duty DUTY is thus updated.

In step s40, the flag FF indicating that the intake pressures P and l have been measured is reset to zero, and then the process moves to step s41. Further, in steps s34 to s36, each of the 7 lags FΔNl.

FΔN2. If either FP or I is not l, the process directly moves to step s41. In step s41, step s25. The opening degree of the flow rate control valve 36 is actually controlled by the control duty DUTY determined in s33 or s39.

To summarize the above operation, when the rotational speed NE suddenly drops or rises, steps s22, s23. s2
4. s25 or step s22°s26. s27. s
28. By the operation of s25, the control duty DUTY is suddenly changed by an increment ΔD2 corresponding to the time rate of change ΔNH. After performing such rapid control, when entering the dead zone W2, rapid return control is performed in steps s34 to s39 by an increment of ΔD3 in order to maintain the intake pressure PH at that point, thereby preventing excessive control. is prevented. When the rotational speed NE is stabilized in this way, normal integral control in step s33 is performed, and stable control is performed with a small gain.

In this way, in the control device 1 according to the present invention, when a sudden drop in the rotational speed NE due to load fluctuation is detected,
The control duty DUTY of the flow rate control valve 36 is changed by an increment ΔD2 corresponding to the rate of change ΔNH of the rotational speed NE to promptly suppress the drop, and when the drop in the rotational speed NE has subsided, the control duty DUTY is changed in advance. Since the control value is rapidly decreased by the predetermined increment ΔD3, it is possible to achieve good stability with a large control gain and without overcontrol that would cause over-boosting.

In addition, even when the rotational speed NE increases due to load fluctuations, it is possible to quickly suppress engine racing and prevent engine stalling due to overcontrol. Speed control can be performed.

Furthermore, threshold values L3 and L4 are set near the target rotational speed NT.
, and the sudden increase in mm due to the increment ΔD2 is unnecessary because it is executed when the measured rotational speed NE is higher than the threshold value L3 during the rise, and when it is less than the threshold value 4 during the fall. This can further improve stability.

In addition, by improving the responsiveness to load fluctuations in this way, the various equipment outputs and sensor measurement results that should be input into the IIJII device fl can be minimized, which simplifies the configuration. be able to.

In addition, when measuring the intake air flow rate, the torque-related parameter may be determined from the pressure and target rotational speed at that time, and the control amount is rapidly adjusted to achieve the target air flow rate. However, the same effect can be obtained.

Effects of the Invention As described above, according to the present invention, when a fluctuation in the rotational speed is detected while the internal combustion engine is idling, the flow rate control valve for idling is controlled at a relatively large rate of change in accordance with the time rate of change of the fluctuation. When the control amount is changed and the time rate of change of the rotational speed approaches zero, a parameter related to the torque of the internal combustion engine at that point can be set, and the set value can be maintained or gradually changed. Since the control amount of the flow control valve is changed rapidly up to this value, for example, when the rotational speed drops, the intake air flow rate is increased at a relatively large rate of change over time, making it possible to prevent engine stalling. Further, when the time rate of change of the rotational speed starts to increase after passing through the minimum value, the intake air flow rate is rapidly reduced to a value that can maintain the torque at that point, and over-control is prevented.

In this way, it is possible to improve responsiveness with a high control gain and to simultaneously improve stability. Furthermore, the number of outputs taken in from various devices and sensors serving as loads can be reduced, and the configuration can be simplified.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a control device 1 for an internal combustion engine according to an embodiment of the present invention and related configurations, FIG. 2 is a block diagram showing a specific configuration of the control device 1, and FIG. 3 is a block diagram showing a specific configuration of the control device 1. 4 is a graph showing changes in the increment ΔD1 during integral control, and FIG. 5 is a graph showing the increment with respect to the control duty DUTY of the flow jl control valve 36 during sudden M control. ΔD2
The graphs showing the changes in FIGS. 6 to 8 are flowcharts for explaining the idle rotation speed control operation. DESCRIPTION OF SYMBOLS 1... Control device, 4.7... Intake pipe, 5... Throttle valve, 6... Surge tank, 8... Fuel injection valve, 10... Internal combustion engine, 14... Exhaust pipe , 20-31・
...detector, 35...side passage, 36...flow control valve,
43... Processing circuit, 45... Memory

Claims (3)

[Claims] (1) The upstream and downstream sides of the throttle valve are connected through an idling bypass side passage, and the rotational speed of the internal combustion engine can be adjusted in advance by changing the control amount of the flow control valve provided in the side passage. In an idle rotation speed control device for an internal combustion engine that maintains a predetermined target rotation speed, a drop/rise in the rotation speed is detected, and the control is performed at a relatively large rate of change in accordance with a time change rate of the drop/rise. When the rate of change over time of the rotational speed becomes zero or almost zero, parameters related to the torque of the internal combustion engine at that point are set, and the set values of the parameters are maintained or gradually reduced. An idle rotation speed control device for an internal combustion engine, characterized in that the control amount is rapidly decreased/increased to a value that can change to a value that can be changed to . (2) The increase/decrease control of the control amount by detecting a fall/increase in the rotational speed is such that when the rotational speed falls, the rotational speed is near the target rotational speed and a predetermined first value higher than the target rotational speed is applied. and when the rotational speed increases, the execution is performed when the rotational speed is near the target rotational speed and higher than a predetermined second value lower than the target rotational speed. The idle rotation speed control device for an internal combustion engine according to item 1. (3) The idle rotation speed control device for an internal combustion engine according to claim 1 or 2, wherein the parameter is an intake pipe pressure.