JP3324772B2 - Engine speed control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine speed control method which improves convergence when the engine speed drops.

[0002]

2. Description of the Related Art In recent years, for the purpose of improving fuel efficiency, the return rotation speed of fuel cut executed at the time of engine deceleration and the idle rotation speed in idle operation tend to be set to a low rotation side. In the mode converging to the idle speed, a delay in the generation of the torque or a shortage of the torque near the idle speed occurs, so that an undershoot of the engine speed tends to occur.

Further, in an engine equipped with a supercharger, an intercooler, or the like in order to increase output, the capacity of the intake system is increased. Occurs, similarly causing an undershoot of the engine speed and, in the worst case, engine stall.

In either case, the cause of the engine speed undershoot or the engine stall is the insufficient engine torque. To cope with this, a dashpot has been conventionally used, The amount of bypass air in the bypass passage that bypasses the throttle valve is increased to compensate for the engine torque shortage. For example, Japanese Patent Application Laid-Open No. 61-197736 discloses that the degree of decrease in the engine speed is not less than a predetermined value. A technique for increasing the amount of bypass air when it is detected is disclosed.

[0005]

However, when the engine decelerates from a higher rotation side to near idle rotation, for example, after racing the engine, the degree of decrease in the amount of air in the intake system increases and the undershoot occurs. It is more likely to occur.

Further, there are many factors that change the deceleration of the engine, such as the presence or absence of an electric load such as a headlight, the aging of the engine, and the atmospheric pressure change with altitude. By controlling the amount of bypass air according to the deceleration of the engine and increasing the generated torque of the engine, undershoot and engine stall can be prevented and good control can be performed. In addition, the control of the bypass air amount becomes inappropriate, resulting in undershoot due to insufficient torque or deterioration in convergence and fuel consumption due to excessive torque.

The present invention has been made in view of the above circumstances, and accurately controls the amount of bypass air drawn into the engine by bypassing the throttle valve to prevent undershoot of the engine speed and stall of the engine. It is an object of the present invention to provide an engine speed control method capable of obtaining optimal convergence.

[0008]

Means for Solving the Problems To achieve the above object,
Therefore, the present invention provides a rotational speed set from an actual engine rotational speed.
The target suction pipe pressure is set based on the target value, and the target suction pipe pressure is set.
Bypass throttle valve according to pressure and suction pipe pressure
An engine that controls the amount of bypass air drawn into the engine
Setting based on the cooling water temperature in the engine speed control method
Between the set target idle speed and the current engine speed
The rotation speed is divided into predetermined ratios based on the
Target which is the target value of engine speed at the time of imaging
Set the number of rotations and set the suction pipe pressure at the previous processing timing.
, Engine speed, current engine speed, and above
Next processing time based on equation of motion from target rotation speed
Target suction pipe pressure at the time of
Target suction pipe pressure, current suction pipe pressure, previous processing
Equation of state of gas from suction pipe pressure at timing
Control of idle speed control valve based on
Calculate the pressure correction amount for correcting the control amount to the intake pipe pressure,
Above target rotation speed, target suction pipe at next processing timing
Pressure, target suction pipe pressure at the previous processing timing, and
And the intake pipe pressure and engine
Cylinder suction based on the number of turns and the gas equation of state
Calculate the air correction amount and set it at the previous processing timing.
The amount of bypass air is adjusted to the pressure compensation amount and the cylinder
Correction by intake air correction amount to set bypass air amount
Then, in accordance with the amount of bypass air, the throttle valve
Installed in a bypass passage connecting the upstream side and the downstream side
It is characterized by controlling an idle speed control valve .

[0009]

[0010]

[0011]

[0012]

According to the present invention, a target set based on a cooling water temperature is set.
Both times based on idle speed and current engine speed
Divide the interval between turns into a predetermined ratio, at the next processing timing
Set the target engine speed at
Set. And the suction pipe pressure at the previous processing timing
, Engine speed, current engine speed, and above
Next processing time based on equation of motion from target rotation speed
Calculate the target suction pipe pressure during running. In addition, the next processing
Target suction pipe pressure at the time of processing and the current suction pipe pressure
And the suction pipe pressure at the previous processing timing
Idle speed control based on the gas state equation
Pressure to correct the control amount of the roll valve for the intake pipe pressure
In addition to calculating the correction amount, the target rotation speed and the next processing
Target suction pipe pressure at timing, previous processing timing
Target suction pipe pressure at the time of
Equation of state of gas from suction pipe pressure and engine speed
Based on this, a cylinder intake air correction amount is calculated. Soshi
And the bypass air volume set at the previous processing timing
Is corrected by the pressure compensation amount and cylinder intake air compensation amount
To set the bypass air flow rate.
In response, communicate the upstream and downstream sides of the throttle valve.
Idle speed control installed in the bypass passage
Control the valve.

[0013]

[0014]

[0015]

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention, FIG. 1 is a flowchart of a rotational speed control process, FIG. 2 is a flowchart of a rotational speed control process, FIG. 3 is a flowchart of a feedback control subroutine, and FIG. FIG. 5 is a time chart showing changes in the engine speed, and FIG. 6 is a time chart showing changes in the engine speed, the suction pipe pressure, and the amount of bypass air.

In FIG. 4, reference numeral 1 denotes an engine (in the figure, an in-line four-cylinder engine). An intake manifold 3 is connected to an intake port 2a formed in a cylinder head 2 of the engine 1, and the intake manifold 3 is connected to the engine. An injector 4 is attached to 3.

Further, an air chamber 5 is connected to the intake manifold 3, and an air cleaner 7 is attached to the upstream side of the air chamber 5 via a throttle valve 6. The air chamber 5 is provided with an intake air temperature sensor 8 and a suction pipe pressure sensor 9.

The throttle valve 6 has a built-in throttle switch which is turned on when the throttle valve is fully closed, a movable switch which moves in accordance with the throttle opening, and a full switch which is turned on when the throttle valve is fully opened. 10 are connected in series. Further, an idle speed control valve (ISCV) 25 is interposed in a bypass passage 24 that connects the upstream side and the downstream side of the throttle valve 6.

The cylinder head 2 of the engine 1
A cooling water temperature sensor 12 faces a cooling water passage 11 formed in the cylinder head 2.
In the collection part of the exhaust manifold 13 communicating with b,
An O2 sensor 14 is provided. Reference numeral 15 denotes a catalytic converter, and reference numeral 16 denotes a muffler.

An ignition plug 17 faces the combustion chamber of the engine 1. The ignition plug 17 is connected to a secondary side of an ignition coil 19 via a distributor 18, and a primary side of the ignition coil 19 For example, it is connected to an igniter 20 integrally provided.

The distributor 18 has a built-in crank angle sensor 21 including an electromagnetic pickup for detecting a crank angle and a cylinder discriminating sensor 22 including an electromagnetic pickup for discriminating a cylinder. The rotor 23 is installed so as to face the outer periphery of the rotating rotor 23.

The crank angle sensor 21 and the cylinder discrimination sensor 22 are not limited to magnetic sensors such as electromagnetic pickups, but may be optical sensors.

On the other hand, reference numeral 31 denotes a control unit (ECU) comprising a microcomputer or the like.
The OM 33, the RAM 34, and the I / O interface 35 are connected to each other via a bus line 36, and a predetermined stabilized voltage is supplied from a constant voltage circuit 37 to each unit.

Reference numeral 38 denotes a battery. The constant voltage circuit 37 of the ECU 31 and the ignition coil 19 are connected to the battery 38 via a relay contact of an ECU relay 39.
And a relay coil of the ECU relay 39 is connected via an ignition switch 40.

The I / O interface 35
Are input port, intake air temperature sensor 8, suction pipe pressure sensor 9, throttle switch 10, cooling water temperature sensor 12, O
The two sensors 14, the crank angle sensor 21, the cylinder discrimination sensor 22, and the vehicle speed sensor 26 are connected, and the battery 38 is connected to monitor the battery voltage. On the other hand, the igniter 20 is connected to the output port, Further, via the drive circuit 41, the injector 4, the ISCV
25 are connected.

The ROM 33 stores a control program and fixed data such as various maps.
The RAM 34 stores data obtained by processing output signals of the sensors and switches and the CPU 32.
The data processed by the calculation is stored.

The CPU 32 sets various control amounts such as a fuel injection amount and an ignition timing based on various data stored in the RAM 34 in accordance with a control program stored in the ROM 33, and outputs corresponding signals to the injector 4. In order to perform air-fuel ratio control, ignition timing control and the like by outputting to the igniter 20 and the like, and to quickly and smoothly converge the engine speed to the idle speed when the engine speed drops when the accelerator is released from the depressed state.
Performs rotation speed control.

Next, a description will be given of a rotation speed control process by the ECU 31. The routine of the rotational speed control process shown in FIGS. 1 and 2 is interrupted every predetermined time (for example, 100 ms), and the engine is released from the high engine speed state by racing until the accelerator pedal is released and converges to the idle speed. This is a routine for controlling the number of revolutions.

In this rotation speed control processing routine, first, in step S101, the vehicle speed VSP is read from the vehicle speed sensor 26, and it is determined whether or not the vehicle speed VSP is zero.
When SP is 0 and the vehicle is stopped, it is determined in step S102 whether or not the idle switch of the throttle switch 10 is ON.

In the above step S101, when VSP ≠ 0,
Alternatively, when VSP = 0 and the idle switch is not ON, the process branches from each step to step S112,
ISCV25 drive pulse signal duty ratio DUTY
Is set to a set value SET (for example, 70%), and in step S113, the rotation speed control end flag F is cleared (F ←
0), indicating that this rotation speed control process is ongoing,
Exit the routine.

On the other hand, when VSP = 0 and the idle switch is ON as a result of the determination in steps S101 and S102, the process proceeds to step S103 via steps S101 and S102, and based on the cooling water temperature TW from the cooling water temperature sensor 12, Set the target idle speed NIDL. The target idle speed NIDL is a target value of the feedback control during the idling operation, and as shown in step S103, smoothly shifts from the engine warm-up state at low temperature to the normal state of warm-up completion. The value is set according to the cooling water temperature TW.

Next, from step S103 to step S1
In step 04, it is determined whether or not the rotation speed control process is being continued by referring to the value of the rotation speed control end flag F. Then, when F = 0, that is, when the rotation speed control process is not completed, the process proceeds from step S104 to step S105, and a target rotation speed Nd which is a target value of the engine rotation speed at the next processing timing is set.

The target engine speed Nd is, as shown in FIG. 5, a current engine speed NE and a target idle engine speed NI.
A value that divides the interval between DL and 1-K1: K1 (K1 is a constant) is defined as (Nd ← K1 ・ (NE-NIDL) + NID
L), the engine speed NE is the reciprocal A / exp of the natural logarithm e
It converges to the target idle speed NIDL along (kt) (A and k are constants).

The value of the constant K1 can be set in the range of 0 to 1, and the convergence time of the engine speed NE can be adjusted by changing the value of K1.

Next, proceeding to step S106, the suction pipe pressure Pr0 at the previous processing timing, the engine speed NE0 at the previous processing timing, the current engine speed NE, and the target rotation set at step S105. From the number Nd,
The target suction pipe pressure Pd at the next processing timing is calculated based on the equation of motion of the rotating body (Pd ← Pr0−K2 ·
{(Nd-NE)-(NE-NE0)}; where K2 is a constant.

That is, since the change in the engine load appears as the behavior of the suction pipe pressure Pr and the engine speed NE, the target suction pipe pressure Pd according to the load change is calculated.
Based on this target suction pipe pressure Pd, a later-described bypass air amount Gd is calculated.

Thereafter, the flow advances to step S107 to correct the amount of air passing through the ISCV 25 (by-pass air amount) from the target suction pipe pressure Pd, the current suction pipe pressure Pr, and the suction pipe pressure Pr0 at the previous processing timing. , A pressure correction amount Gp, which is a correction value of the suction pipe pressure, is calculated based on a gas state equation (Gp ← K3Ｋ (Pd−Pr) − (Pr−Pr).
0)｝; where K3 is a constant). In step S108, the target engine speed Nd, the target suction pipe pressure Pd, and the suction pipe pressure Pr0 at the previous processing timing and the engine speed NE0 are similarly used to determine the gaseous state. Based on the equation of state, a cylinder intake air correction amount Gcy, which is a correction value of the amount of air taken into the cylinder, is calculated (Gcy ← K4 · (Nd · Pd−NE0 · Pr0); where K4 is a constant).

Next, from step S108 to step S1
09, the pressure correction amount Gp obtained in step S107,
The cylinder intake air correction amount Gcy obtained in step S108
Is calculated from the current processing timing until the next processing timing (Gd ← Gr).
+ Gp + Gcy; where Gr is the bypass air amount controlled from the previous processing timing to the current processing timing).

Next, the process proceeds to step S110,
When the duty ratio DUTY corresponding to the bypass air amount Gd set in S109 is set in the drive pulse signal of the ISCV 25, the end of the rotation speed control mode is checked in step S111. It is determined whether the engine speed NE is within a predetermined speed range including the target idle speed NIDL, or whether the amount of change in the engine speed NE is equal to or less than a predetermined value. Is determined by checking whether or not is established continuously for a predetermined number of times.

If it is determined in step S111 that the control has not been completed, the rotational speed control end flag F is cleared in step S113 (F ← 0), and the routine exits. Then, the flow branches to step S114 to execute a normal idle speed control by calling a feedback control subroutine. In step S115, a speed control end flag F is set (F ← 1), and the routine exits.

That is, the target rotation speed Nd is set for each predetermined time, and the bypass air amount Gd is determined so that the engine rotation speed after the lapse of the predetermined time becomes the target rotation speed Nd.
In order to repeat the control of step 5, the control error is cleared every predetermined time and the trajectory is corrected. Even if a deviation between the target and the actual occurs, there is no unreasonable correction to the target, and as shown in FIG. Good convergence is obtained.

Also, since the change in load is always grasped from the behavior of the engine speed and the suction pipe pressure, and the amount of bypass air is determined in accordance with the load, the change with time of the engine, the electric load such as headlights, There is no deterioration in rotation convergence due to a change in the power steering load or the like, a fall in the engine speed is prevented, and engine stall can be avoided.

When the engine speed NE converges to the target idle speed NIDL in the above-described speed control routine,
The routine shifts to the normal idle feedback control shown in FIG. 3, and in step S201, a differential rotation DELTAN between the current engine speed NE and the target idle speed NIDL is calculated (DELTAN ← NE-NIDL). Based on the differential rotation DELTAN and the engine speed NE,
Set the feedback speed DFB.

The feedback speed DFB is a correction value (%) of the duty ratio DUTY when performing feedback control of the engine speed NE to the target idle speed NIDL. As shown in step S202, the engine speed NE is calculated. When the differential rotation DELTAN is a negative value, that is, when the current engine rotation speed NE is lower than the target idle rotation speed NIDL, the differential rotation DEL is stored.
When the absolute value of TAN is large and the engine speed NE is high, the correction value is such that the duty ratio DUTY is increased. When the differential rotation DELTAN is a positive value,
When the current engine speed NE is higher than the target idle speed NIDL, the correction value is such that the differential rotation DELTAN is large, and the higher the engine speed NE, the smaller the duty ratio DUTY.

Then, steps S202 to S2 are performed.
Proceeding to 03, the feedback speed DFB set in step S202 is added to the duty ratio DUTY set in the previous execution of the routine to set the current duty ratio DUTY (DUTY ← DUTY + DFB), and in step S204
This duty ratio DUTY is set in the drive pulse signal of the ISCV 25, and the routine exits.

In this embodiment, the deceleration from the high engine speed in the engine racing when the vehicle is stopped has been described. However, the present invention is not limited to this, and can be applied to the deceleration in coasting traveling. ,
Further, the idle speed can be controlled to be constant by the speed control of the present invention instead of the feedback control.

[0048]

As described above, according to the present invention, the cold
The target idle speed set based on the cooling water temperature and the current
The engine speed is divided into a predetermined ratio based on the engine speed.
Engine speed at the next processing timing
Set the target number of revolutions, which is the target
Revolution speed to target idle speed along reciprocal of natural logarithm
It is possible to converge, and when the engine speed converges
The interval can be set accurately. And the previous processing
The suction pipe pressure at the timing, the engine speed, and the current
Equation of motion is calculated from the engine speed and the above target speed.
Calculate the target suction pipe pressure at the next processing timing
Output, it depends on the behavior of the suction pipe pressure and the engine speed.
The change in engine load accurately and respond to the load change.
The target suction pipe pressure can be properly obtained. In addition,
Target suction pipe pressure at the time of each processing and current suction
Pipe pressure and suction pipe pressure at previous processing timing
And idle speed based on the equation of state of the gas from
To compensate the control amount of the control valve for the intake pipe pressure
Of the target rotation speed and the next
Target suction pipe pressure at the processing timing of
Target suction pipe pressure at the time of
From the suction pipe pressure and engine speed during
Calculate the cylinder intake air correction amount based on the equation
The amount of bypass air set at the time of
By these pressure compensation amount and cylinder intake air compensation amount
Compensate and set the bypass air amount.
Corresponding to the upstream and downstream sides of the throttle valve.
Idle speed control installed in the bypass passage
Controls the troll valve, so the engine speed and suction
Always grasp changes in engine load from behavior with inlet pressure
Target the amount of bypass air in response to changes in engine load.
It is possible to accurately correct for changes in the engine over time.
And changes in electrical loads, power steering loads, etc.
Deterioration of the convergence of the engine speed can be eliminated. Also,
At each processing timing, at the next processing timing
Set the target engine speed, which is the target engine speed,
Target rotational engine Rotation speed at times of processing timing
Idle speed by correcting the bypass air amount to
Control error because of repeated control of
Can be corrected at each processing timing to correct the trajectory.
Possible, even if there is a deviation between the target value and the actual value,
To correct targets and improve convergence of engine speed.
Can be up. That is, the next processing timing
Pipe pressure and cylinder suction sucked into cylinder
In response to the air flow,
The bypass air amount can be corrected. Therefore, the eye
Always adequately control the bypass air flow when shifting to dollar operation
Control during the transition to idle operation.
Engine speed undershoot and engine stall
To ensure optimal convergence.
You.

[Brief description of the drawings]

FIG. 1 is a flowchart of a rotation speed control process.

FIG. 2 is a second flowchart of a rotation speed control process.

FIG. 3 is a flowchart of a feedback control subroutine.

FIG. 4 is a schematic configuration diagram of an engine control system.

FIG. 5 is a time chart showing a change in engine speed.

FIG. 6 is a time chart showing changes in engine speed, suction pipe pressure, and bypass air amount;

[Explanation of symbols]

1 Engine 24 Bypass passage 25 ISCV NE Engine speed Nd Target speed NIDL Target idle speed Gd Bypass air amount Pd Target suction pipe pressure Gp Pressure correction amount (correction value of suction pipe pressure) Gcy Cylinder suction air correction amount (to cylinder) Correction value of the amount of air taken in)

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F02D 41/16 F02D 33/00 310 F02D 41/12 315 F02D 45/00 322 F02M 69/32

Claims (1)

(57) [Claims] An engine speed target set from an actual engine speed.
The target suction pipe pressure is set based on the target suction pipe pressure.
Bypass the throttle valve according to the force and suction pipe pressure.
Engine that controls the amount of bypass air drawn into the engine
The target idle speed set based on the coolant temperature and the current idle speed.
Based on the current engine speed, a certain ratio between the two speeds
Divide the engine speed at the next processing timing
Set the target number of revolutions, which is the target value of the number of revolutions, and set the suction pipe pressure and engine
And the current engine speed and the target
Target suction at next processing timing based on dynamic equation
Calculate pipe pressure, target suction pipe pressure at next processing timing, current suction
Pipe pressure, suction pipe pressure at previous processing timing
Based on the gas state equation
Pressure for compensating intake pipe pressure for control amount of troll valve
Calculate the force correction amount, and set the target rotation speed and the target suction pipe at the next processing timing.
Pressure, target suction pipe pressure at the previous processing timing, and
And the intake pipe pressure and engine
Cylinder suction based on the number of turns and the gas equation of state
Calculate the air correction amount and increase the bypass air amount set at the previous processing timing.
According to the pressure compensation amount and the cylinder intake air compensation amount
Make the correction to set the bypass air amount, and
Correspondingly communicates upstream and downstream of the throttle valve
Speed control installed in the bypass passage
An engine speed control method characterized by controlling a roll valve .