JPH1030476A - Engine speed control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent sudden change of an engine speed by controlling by-pass air quantity at a higher value than the lower limit value subtracting the predetermined value from the learned value, when by-passing air quantity is decreased in setting the by-pass air quantity for bypassing a throttle valve, and in the case of increasing the by-pass air quantity, controlling of the by-pass air quantity lower than the higher limit value subtracting the predetermined value from the learned value. SOLUTION: During operation of an engine 1, when a control device 20 discriminates that a throttle valve 4 is closed, at first, whether or not an engine is warmed up condition is discriminated by practicing routine engine idling frequency control and if YES is discriminated, a target engine speed is set in complying with on-off condition of an air conditioning switch 12. Subsequently discriminating if the actual rotational frequency is made to converge at the target engine speed, and if NO is discriminated, the negative control gain shall be found from the deviation the engine speed, ISC valve (by-pass air quantity control valve) 13 shall be controlled by comparing the value adding the negative control gain to the last value of the by-pass air quantity for the ISC with the lower limit value subtracting the predetermined value from the learned value, and according to the resulted value.

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 device that adjusts the engine speed to a target speed by adjusting the amount of bypass air during idle operation without using an idle switch. The present invention relates to an engine speed control device that prevents sudden increase and decrease and excessive increase and decrease.

[0002]

2. Description of the Related Art As is well known, many engine control devices are provided with a throttle valve open / closed state detecting device for detecting whether or not a throttle valve of an engine is almost fully closed. Various engine controls are performed based on the detection results. Further, a means for detecting an idling operation state is provided in order to constantly control the number of revolutions during idling operation (usually referred to as ISC).

For example, Japanese Patent Publication No. 53-42854 discloses a fuel injection device that stops fuel supply when the throttle valve is closed and the engine speed is higher than a predetermined speed. ing. Japanese Patent Publication No. Sho 61-19818 discloses an engine speed control device that performs closed loop control of an engine speed to a target speed when the throttle valve is in a closed state and the engine speed is lower than a predetermined speed. It is shown.

In these conventional devices, the closed state of the throttle valve is detected by providing a throttle opening sensor that responds to opening and closing of the throttle valve, an idle switch that is turned on or off when the throttle is fully closed, and the like.

When the closed state of the throttle valve is detected, the bypass air amount is increased if the engine speed is lower than the target speed, and the bypass air amount is decreased if the engine speed is higher than the target speed. By doing
The engine speed is controlled to converge to the target speed.

However, when dedicated devices such as a throttle opening sensor and an idle switch are provided as in the device disclosed in the above-mentioned publication, the entire device becomes expensive,
Cost reduction cannot be realized.

Therefore, as disclosed in, for example, Japanese Patent Application Laid-Open No. 7-34941, an apparatus for detecting the open / close state of a throttle valve based on the intake pipe pressure without using a dedicated device has been proposed.

In this case, a pressure value Pba obtained by adding a predetermined value to the predicted fully closed intake pipe pressure and an actually detected intake pipe pressure P
b, and if Pba> Pb, it is determined that the throttle valve is closed, and the engine speed is feedback controlled. However, in such idle speed control, the speed may suddenly increase or decrease under various conditions.

For example, when the driver slightly steps on the accelerator pedal, the throttle valve is slightly opened and the engine speed slightly increases. Therefore, the amount of bypass air is reduced to reduce the engine speed to the target speed. To converge. However, when the foot is released from the accelerator pedal in such a state where the bypass air amount is small, the throttle valve is suddenly fully closed and the engine speed is rapidly decreased, and in some cases, engine stall may occur.

When an electric load such as an air conditioner or a power window is generated during the rotation speed feedback control, the engine rotation speed is reduced. Therefore, the amount of bypass air is increased to converge the engine rotation speed to the target rotation speed. To try. However, when the electric load is turned off in the state where the bypass air amount is large, the engine speed rapidly increases.

[0011]

As described above, when the conventional engine speed control device is provided with a dedicated device such as a throttle opening sensor or an idle switch, the entire device becomes expensive, and the cost can be reduced. There was a problem that it could not be realized.

When a closed state of the throttle valve is detected based on the intake pipe pressure without using a dedicated device,
There is a problem that the engine speed suddenly increases or decreases depending on conditions due to the operation of the speed feedback control.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to improve the reliability of detecting the open / close state of a throttle valve and to reduce the cost.
It is an object of the present invention to provide an engine speed control device that prevents an abrupt increase or decrease in engine speed even under various conditions.

[0014]

According to the present invention, there is provided an engine speed control apparatus comprising: an intake pipe for supplying an air-fuel mixture to an engine; a throttle valve provided in the intake pipe for adjusting an engine intake amount; A bypass passage connected between the upstream and the downstream of the throttle valve so as to bypass the valve, a bypass air amount adjusting valve provided in the bypass passage to adjust a bypass air amount, and a pressure sensor for detecting a pressure of an intake pipe; A throttle valve open / closed state detecting means for detecting the open / closed state of the throttle valve based on the intake pipe pressure detected by the pressure sensor; and controlling the bypass air amount adjusting valve when the throttle valve is closed to control the bypass air amount. Adjusting the engine speed and converging the engine speed to the target speed; and controlling the engine speed when the engine speed converges to the target speed. A bypass air amount storage means for storing the bypass air amount as a learning value, wherein the engine speed control means sets the bypass air amount when the throttle valve is in the closed state, and reduces the bypass air amount. Is to limit the bypass air amount to a lower limit obtained by subtracting a predetermined value from a learned value, and to limit the bypass air amount to an upper limit obtained by adding a predetermined value to the learned value when increasing the bypass air amount. It is.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram showing a first embodiment of the present invention, in which a speed density SPI for determining a fuel injection amount based on an engine speed and an intake pipe pressure is shown.
This shows a case where the present invention is applied to an engine of fuel control by (single point injection).

In FIG. 1, reference numeral 1 denotes a well-known spark ignition type engine mounted on, for example, an automobile, 2 denotes an air cleaner for purifying intake air, 3 denotes an intake pipe through which the intake air passes through the air cleaner 2, and 4 denotes intake air. A throttle valve provided in the pipe 3 for adjusting the amount of intake air.
Mainly sucks combustion air from the upstream side through the air cleaner 2, the intake pipe 3, and the throttle valve 4.

The intake pipe 3 includes, from the upstream side, an air intake 3a, a throttle body 3b whose opening cross-sectional area is adjusted by a throttle valve 4, and an intake manifold 3c.
It is composed of Reference numeral 5 denotes a water temperature sensor that detects the temperature of the cooling water (described later), and outputs a detection signal corresponding to the detected water temperature.

Reference numeral 6 denotes a bypass air passage provided so as to bypass the throttle valve 4 in the throttle body 3b, and an inlet and an outlet are provided upstream and downstream of the throttle valve 4 of the throttle body 3b. . Reference numeral 6a denotes a first idle air passage (hereinafter, referred to as an FIA passage) provided in the bypass air passage 6.

Reference numeral 7 denotes a wax type first idle air valve (hereinafter referred to as FI) provided in the middle of the FIA passage 6a.
Reference numeral 8 denotes cooling water that covers the outer periphery of the engine 1. The FIA valve 7 automatically adjusts the cross-sectional area of the FIA passage 6a according to the temperature of the cooling water 8, and controls a part of the bypass air amount.

Another inlet of the bypass air passage 6 is
Throttle body 3 further upstream than the other inlet
and a bypass passage 9 for an air conditioner and a bypass passage 10 for idle speed control (hereinafter referred to as an ISC bypass passage) 10 which are positioned in parallel with each other. The common outlet of each bypass passage 9 and 10 is located in the FIA passage 6a downstream of the FIA valve 7.

Reference numeral 11 denotes an air conditioner idle up solenoid valve (hereinafter, referred to as an ACIUS valve) for controlling an opening cross-sectional area of the air conditioner bypass passage 9, and reference numeral 12 denotes an air conditioner switch operated by an occupant of an automobile. AC
The IUS valve 11 is fully opened and fully closed according to the ON / OFF of the air conditioner switch 12, and controls a part of the bypass air amount. The amount of bypass air when the ACIUS valve 11 is fully opened can be manually adjusted according to the load of the air conditioner.

Reference numeral 13 denotes an idle speed control solenoid valve (hereinafter, referred to as an ISC solenoid valve) for controlling an opening cross-sectional area of the ISC bypass passage 10. The opening of the solenoid valve 13 is adjusted according to a duty ratio of a drive signal. A part of the bypass air amount is controlled so that the engine speed during idling becomes the target speed. Therefore, the ISC solenoid valve 13 functions as a bypass air amount adjusting valve.

With the above configuration, the opening cross-sectional area of the bypass air passage 6 (effective cross-sectional area of the bypass air passage) is FIA.
Controlled by the valve 7, the ACIUS valve 11, and the ISC solenoid valve 13, the bypass air amount is controlled. The bypass air that has passed through the bypass air passage 6 is introduced into the engine 1 for combustion.

Reference numeral 14 denotes a pressure sensor provided with a pressure inlet further downstream than the outlet of the bypass air passage 6. The pressure sensor 14 detects the pressure (intake pipe pressure) Pb in the intake pipe 3 by an absolute value. A detection signal corresponding to the detected intake pipe pressure Pb is output. By detecting the intake pipe pressure Pb before the start of the engine 1, the pressure sensor 14 also functions as an atmospheric pressure sensor.

Reference numeral 15 denotes a single injector provided in the throttle body 3b further upstream than the inlet of the bypass air passage 6, which is connected to a fuel system (not shown), and is used for intake for combustion taken into the engine 1. Fuel corresponding to the amount of air is injected and supplied by opening the valve. The injected fuel is supplied to the engine 1 as a mixture with the intake air.

Reference numeral 16 denotes an ignition coil comprising a primary winding and a secondary winding, and 17 denotes an igniter connected to an ignition control system. The primary side of the ignition coil 16 is the igniter 1
7, a high voltage generated from the secondary side is supplied to a spark plug (not shown) provided for each cylinder of the engine 1 to perform ignition. in this case,
The output signal of the primary winding of the ignition coil 16 is also used as a rotation signal synchronized with the drive timing of the engine 1.

Reference numeral 18 denotes an exhaust pipe of the engine 1, and reference numeral 19 denotes an exhaust gas purifying catalyst provided downstream of the exhaust pipe 18.
The exhaust gas from the engine 1 is supplied from the exhaust pipe 18 to the catalyst 19.
Through which harmful components are removed and at least a portion is released to the atmosphere.

Reference numeral 20 denotes a microcomputer (to be described later)
The control device is configured to calculate an idle speed control amount, a fuel injection amount, and the like by predetermined arithmetic processing based on various switch signals, sensor signals, and the like, and to drive and control the ISC solenoid valve 13, the injector 15, and the like. . Reference numeral 21 denotes a battery serving as a power supply power source for operating the control device 20, and 22 denotes a battery 21 and the control device 2
This is a key switch inserted between "0".

FIG. 2 is a block diagram showing a specific configuration of the control device 20 in FIG. 1, wherein 100 is a microcomputer and 101 to 103 are first to third inputs for inputting various signals to the microcomputer 100. An interface circuit 104 is an output interface circuit for outputting a calculation result from the microcomputer 100 as a control signal, and 105 is a first power supply circuit for operating the microcomputer 100.

The first input interface circuit 101 takes in the primary side signal from the ignition coil 16, the second input interface circuit 102 takes in analog signals from the water temperature sensor 5 and the pressure sensor 14, and the third input interface The circuit 103 captures an on / off signal of the air conditioner switch 12. Also, the output interface circuit 104
A control signal is output to the ISC solenoid valve 13 and the injector, and the first power supply circuit 105
Power is supplied from the battery 21 via the power supply 2.

The microcomputer 100 includes the following components 200 to 209. Reference numeral 200 denotes a CPU that performs various arithmetic processing and determination, and 201 denotes an engine 1
A counter for measuring the rotation cycle of the A / D converter, a timer 202 for measuring a driving time for control, and an A / A 203 for converting an analog signal input via the second interface circuit 102 into a digital signal. D converter, 204
Reference numeral denotes an input port for transmitting a digital signal input through the third interface circuit 103 to the CPU 200.

A RAM 205 functions as a work memory of the CPU 200, a ROM 206 stores a main flow program (to be described later) for the operation of the CPU 200 and various maps, and an output 207 for outputting a command signal of the CPU 200. A port 208 is a timer for measuring a duty ratio of a drive signal supplied to the ISC solenoid valve 13, and a reference numeral 209 is a common bus connecting the CPU 200 and various components 201 to 208.

The control device 20 includes a throttle valve open / closed state detecting means for detecting the open / closed state of the throttle valve 4 based on the intake pipe pressure Pb detected by the pressure sensor 14, and an ISC when the throttle valve 4 is closed. An engine speed control means for controlling the solenoid valve 13 (bypass air amount adjusting valve) to adjust the bypass air amount and converge the engine speed to the target speed; And learning value storage means for storing the bypass air amount as a learning value.

The throttle valve open / closed state detecting means in the control device 20 determines that the throttle valve 4 is closed when the intake pipe pressure Pb is smaller than a value obtained by adding a predetermined value to the estimated pressure value.

When setting the bypass air amount when the throttle valve 4 is in the closed state, the engine speed control means sets a lower limit value obtained by subtracting a predetermined value from the learned value when the bypass air amount is reduced. In the case where the bypass air amount is limited and the bypass air amount is increased as described above, the bypass air amount is limited to an upper limit value obtained by adding a predetermined value to the learning value.

Hereinafter, the general operation of the control device 20 will be described with reference to FIGS. First, an ignition signal obtained from the primary side of the ignition coil 16 is subjected to waveform shaping or the like via a first input interface circuit 101, and becomes an interrupt command signal to become an interrupt command signal.
Input to 0.

Each time this interrupt is issued, the CPU 200 in the microcomputer 100
Is read and the engine 1 is calculated from the difference from the previous counter value.
And the rotation speed data Ne representing the engine rotation speed is calculated.

The water temperature sensor 5 and the pressure sensor 14
Analog signal from the second input interface circuit 1
02, a noise component is removed, amplified, etc., and further, via an A / D converter 203, an intake pipe pressure value Pb representing the intake pipe pressure and a cooling water temperature value representing the temperature of the cooling water 8 It is converted into each digital data of WT. Here, the intake pipe pressure value Pb is proportional to the detected intake pipe pressure, and the cooling water temperature value WT is proportional to the detected cooling water temperature.

The on / off signal from the air conditioner switch 12 is converted to a digital signal level via the third input interface circuit 103 and then input to the input port 204.

CPU 2 in microcomputer 100
00 is, for example, 10 based on these input data.
While calculating the bypass air control amount every 0 msec,
The driving time of the injector 15 is calculated. In addition, by synchronizing with the generation of the interrupt command signal, the timer 208 measures the time at the duty ratio corresponding to the bypass air control amount, and similarly measures the time corresponding to the fuel injection amount by the timer 202.

During measurement by the timer 208 or 202, a drive command is given from the CPU 200 to the output interface circuit 104 via the output port 207. As a result, the output interface circuit 104
A drive signal having the above duty ratio is supplied to the ISC solenoid valve 13 to control the opening of the ISC solenoid valve 13. Further, a drive signal is supplied to the injector 15 and the injector 1 is driven for the calculated drive time τ.
5 is driven to open.

The first power supply circuit 105 includes a key switch 22
Is turned on, the voltage of the battery 21 is adjusted to a constant voltage and supplied to the microcomputer 100 to operate the microcomputer 100.

Next, the schematic operation of the first embodiment of the present invention will be described with reference to the flowchart of FIG. The control flow of FIG.
The contents are the same as those described in JP-A-41.

In FIG. 3, when the control device 20 is turned on by turning on the key switch 22, the CPU 200 in the microcomputer 100 starts operating. That is, in step S1, the start flag indicating that the initialization of the RAM 205 has been completed is reset to 0.

Then, the process proceeds to step S2, where actual speed data Ne representing the engine speed is obtained from the rotation period already detected by the ignition signal from the ignition coil 16, and is read. Further, the process proceeds to step S3, where an intake pipe pressure value Pb representing the intake pipe pressure detected by the pressure sensor 14 is read. Similarly, the process proceeds to step S4, where a coolant temperature value WT representing the coolant temperature detected by the coolant temperature sensor 5 is read.

Next, the process proceeds to step S5, where it is determined whether the start flag is 0 or not.
If it is determined as ES), the process proceeds to step S6, where the intake pipe pressure value Pb is stored in the RAM 205 as the atmospheric pressure value Pa, and after the process of step S6 is completed, the process proceeds to step S7.
If it is determined in step S5 that the start flag is 1 (that is, NO), the process proceeds to step S7 without performing the process of step S6.

In step S7, the throttle valve 4
The open / closed state detection routine is performed, and if it is determined that the throttle valve 4 is in the closed state, the valve closing flag is set to 1;
When it is determined that the throttle valve 4 is not in the closed state, the valve closing flag is reset to 0.

Subsequently, the process proceeds to step S8, where the RAM 20
The start flag is set to 1 to indicate that the initialization of 5 has been completed. Further, the process proceeds to step S9, and executes a process of an idle speed control routine (details thereof are shown in FIGS. 4 and 5).

Then, the process proceeds to a step S10, wherein it is determined whether or not the valve closing flag is 1, and the valve closing flag = 1 (that is, YES:
When it is determined that the throttle valve 4 is in the closed state, the process proceeds to step S11 and the engine speed Ne is set to 15
It is determined whether or not it is not less than 00 rpm. If Ne ≧ 150
If it is determined to be 0 rpm (that is, YES), it is determined that the engine 1 is in a decelerating state, and the process proceeds to step S12, where the drive time τ of the injector 15 is set to 0 to stop fuel injection.

On the other hand, in step S11, Ne <1
If it is determined to be 500 rpm (that is, NO), the process proceeds to step S13, and the drive time τ of the injector 15 during normal operation is obtained. If it is determined in step S10 that the valve closing flag = 0 (that is, NO), the process proceeds to step S13 without executing the determination step S11.

In step S13 for obtaining the drive time τ of the injector 15 during normal operation, first, a two-dimensional map is mapped from the engine speed Ne and the intake pipe pressure value Pb, and the volume efficiency CEV (Ne, Pb) is obtained. Obtained by calculation. Next, the routine proceeds to step S14, where the cooling water temperature value W
The one-dimensional map is mapped from T, and the warm-up increase coefficient CW
T (WT) is obtained by calculation.

Finally, the process proceeds to step S15, where the constant K,
Using the intake pipe pressure value Pb, the volumetric efficiency CEV, and the warm-up increase coefficient CWT, the drive time τ of the injector 15 is obtained according to the following equation.

Τ = K × Pb × CEV × CWT

After steps S15 and S12, the process returns to step S2 to repeat the above operation.

Here, the basic operation of the throttle valve open / closed state detection routine (step S7) according to the first embodiment of the present invention will be schematically described. First, the fully closed intake pipe pressure value corresponding to each engine speed Ne is stored as a map value, and the fully closed intake pipe pressure value corresponding to the current engine speed Ne and the current intake pipe pressure detection value Pb are stored. If the current intake pressure detection value Pb is smaller, it is determined that the throttle valve 4 is fully closed.

This eliminates the need for a throttle opening sensor, an idle switch that is turned on or off when the throttle valve 4 is fully closed, and can reduce the cost of the entire apparatus.

Next, the flowcharts of FIGS.
The specific processing of the idle speed control routine (step S9) in FIG. 3 will be described with reference to the map characteristic diagrams in FIGS. 6 and 7 and the explanatory diagram in FIG.

First, in step S90 in FIG.
It is determined whether or not the valve closing flag is 1 (that is, the throttle valve 4 is closed). If the valve closing flag is 1 (that is, YES) and the throttle valve 4 is closed, the process proceeds to step S91, and the cooling is performed. It is determined whether or not the water temperature value WT is equal to or higher than a value corresponding to 70 ° C. (the engine 1 is sufficiently warmed up).

If the cooling water temperature value WT is equal to or more than 70 ° C. (ie, YES) and the engine 1 is sufficiently warmed up, the process proceeds to step S92, and the air conditioner switch 12 is turned on (ie, the air conditioner It is determined whether or not this is the case.

If the air conditioner switch 12 is off (ie, NO), the process proceeds to step S93, where the target speed data Nt representing the target speed is set to a value corresponding to 800 rpm, and the air conditioner switch 12 is turned on (ie, NO). YE
If S), the process proceeds to step S94, where the target rotation speed data Nt is set to a value corresponding to 1000 rpm.

After the target speed data Nt is set in step S93 or S94, the process proceeds to step S95, and it is determined whether or not the actual speed data Ne converges on the target speed data Nt (step S95).

If it is determined that the actual rotational speed data Ne converges on the target rotational speed data Nt (that is, YES), the ISC bypass air amount QSSC (hereinafter, referred to as the ISC solenoid valve 13) when the convergence is achieved. Is stored as a learning value QLRN (step S96).

At this time, when the air conditioner switch 12 is off, the learned value storage means in the control device 20 stores the ISC air amount QSSC at the time of the off as a learned value QLRN (OFF), and turns on the air conditioner switch 12. In the case of, the ON-state ISC air amount QISC is set to the learning value QLRN (O
N).

On the other hand, if it is determined in step S95 that the actual rotational speed data Ne does not converge on the target rotational speed data Nt (ie, NO), step S96 is skipped and the process proceeds to step S97 (see FIG. 5). Advance, 10
It is determined whether the timing is every 0 msec.

If it is determined that the timing is not every 100 msec (ie, NO), the idle speed control routine of FIGS.
If it is determined that the timing is every 0 msec (ie, YES), the process proceeds to step S98.

In step S98, the actual rotation speed data Ne is compared with the target rotation speed data Nt.
If> Nt, the process proceeds to step S99. If Ne = Nt, the process proceeds to step S103. If Ne <Nt, the process proceeds to step S104.

In step S99, a rotation speed deviation ΔN (= N) between the actual rotation speed data Ne and the target rotation speed data Nt.
Ne−Nt), and a negative control gain (−KI) for converging the engine speed to the target speed is obtained by mapping a one-dimensional map of the speed deviation ΔN. For example, a map as shown in FIG. 6 is used as a one-dimensional map for obtaining the control gain -KI from the rotation speed deviation ΔN.

Subsequently, a negative control gain (-KI) is added to the previous value (value before 100 msec) of the ISC air amount QSSC.
Is compared with a lower limit value (QLRN-QA) obtained by subtracting a predetermined value QA from the learning value QLRN, and it is determined whether or not the following relationship holds (step S100).

QSSC (before 100 msec) -KI> QLRN-QA

At this time, the learning value QLRN is, as described above, the learning value Q corresponding to the ON / OFF of the air conditioner switch 12.
LRN (ON) or QLRN (OFF) is used.

In the idle speed control, if the engine speed Ne is higher than the target speed Nt,
Feedback control is performed such that Ne = Nt by reducing the ISC air amount QSSC by a negative control gain −KI, but the predetermined value QA in step S100 is I
It serves as a limit value for preventing the SC air amount QISC from being excessively reduced.

If YES is determined in step S100, the ISC air amount QSSC is
(100 msec before)-Update to -KI (step S10)
1), and proceed to step S103.

Also, the QSSC (before 100 msec) -K
If it is determined that I ≦ QLRN-QA (that is, NO), the ISC air amount QSSC is clipped to a value (QLRN-QA) obtained by subtracting the predetermined value QA from the learning value QLRN (step S102), and the process proceeds to step S103. move on.

In step S103, the ISC solenoid valve 13 is operated by a mapping operation using a one-dimensional map according to the updated ISC air amount QISC.
Is driven to obtain a drive signal duty ratio for achieving the target air amount. As the one-dimensional map for obtaining the duty ratio, for example, a map as shown in FIG. 7 is used.

The drive signal at this time is as shown in FIG. 8, and the ISC solenoid valve 13 is turned on.
The time during the cycle is TON, and the time of one cycle is T
Then, the duty ratio is (TON / T) × 100
[%]. This duty ratio is proportional to the opening of the ISC solenoid valve 13. Thus,
When the duty ratio calculation (step S103) is performed,
The idle speed control routine of FIG. 4 and FIG.

On the other hand, in step S98, Ne <N
If it is determined that the engine speed Ne is equal to t, the engine speed Ne is set to the target engine speed Ne by one-dimensional mapping of the engine speed difference ΔN between the target engine speed data Nt and the actual engine speed data Ne (see FIG. 6). A positive control gain (+ KI) for converging to Nt is obtained.

Subsequently, the ISC air amount QSSC (100
msec before) and an upper limit value (QLRN) obtained by adding a predetermined value QB to the learning value QLRN.
+ QB) to determine whether the following relationship is satisfied (step S105).

QSSC (before 100 msec) + KI <QLRN + QB

The learning value QLRN can be set to QLRN (ON) or Q
LRN (OFF) is used. The predetermined value QB is
When Ne <Nt, it acts as a limit value for preventing the ISC air amount QISC from being excessively increased.

If the determination in step S105 is YES, the ISC air amount QSSC is
(Before 100 msec) + KI (step S10)
6) The process proceeds to step S103. In addition, the QISC (10
0 msec before) + KI ≧ QLRN + QB (that is, N
O), the ISC air amount QISC is changed to QLR.
Clip to N + QB (step S107) and proceed to step S103.

On the other hand, in step S90 in FIG.
When it is determined that the throttle valve 4 is not in the closed state (valve closed flag = 0), or when it is determined in step S91 that the engine is not sufficiently warmed up (cooling water temperature value WT <70 ° C. equivalent value). , The process proceeds to step S108 (see FIG. 5).

In step S108, the ISC air amount value QISC is set to a predetermined value QOPEN for setting the target air amount during the open control, and thereafter, the process proceeds to the duty ratio calculation step S103, and the idle ratio in FIGS. The rotation speed control routine ends.

As described above, during the ISC feedback control, when the engine speed Ne is larger than the target speed Nt, the reduction control amount of the ISC air amount QISC is limited by the predetermined value QA. Even if the closed state of the throttle valve 4 is detected in a state where the valve 4 is slightly opened, the ISC air amount QISC is not excessively reduced.

When the engine speed Ne is equal to the target speed N
If it is smaller than t, the increase control amount of the ISC air amount QISC is limited by the predetermined value QB. Therefore, even if the engine load increases and the engine speed decreases, I
The SC air amount QISC is not excessively increased.

Therefore, it is possible to prevent a sudden increase or decrease and an excessive increase or decrease of the bypass air amount. Further, since the throttle valve opening / closing state can be detected based on the intake pipe pressure Pb without using a dedicated device, the cost can be reduced and the reliability of the rotational speed feedback control is not impaired.

[0086]

As described above, according to the present invention, the intake pipe for supplying the air-fuel mixture to the engine, the throttle valve provided in the intake pipe for adjusting the engine intake air amount, and the throttle valve are bypassed. A bypass passage connected between the upstream and the downstream of the throttle valve, a bypass air amount adjusting valve provided in the bypass passage to adjust a bypass air amount, a pressure sensor for detecting a pressure of the intake pipe, and a pressure sensor for detecting the pressure. Throttle valve open / closed state detecting means for detecting the open / closed state of the throttle valve based on the intake pipe pressure to be controlled; and, when the throttle valve is in the closed state, controlling the bypass air amount adjusting valve to adjust the bypass air amount. An engine speed control means for causing the engine speed to converge to the target engine speed; And a bypass air amount storing means for storing the bypass air amount.When the engine speed control means sets the bypass air amount when the throttle valve is in the closed state, the engine speed control means determines a predetermined amount from the learned value when the bypass air amount is reduced. When the bypass air amount is limited to a value equal to or greater than the lower limit obtained by subtracting the value and the bypass air amount is increased, the bypass air amount is limited to a value equal to or less than the upper limit obtained by adding a predetermined value to the learned value. This has the effect of improving the reliability of detecting the open / closed state and realizing cost reduction, and obtaining an engine speed control device that prevents a sudden increase or decrease in the engine speed even under various conditions.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a block diagram showing a specific functional configuration of the control device according to the first embodiment of the present invention.

FIG. 3 is a flowchart showing an overall operation of the first embodiment of the present invention.

FIG. 4 is a flowchart showing an idle speed control process according to the first embodiment of the present invention.

FIG. 5 is a flowchart showing an operation subsequent to FIG. 4 in the idle speed control process according to the first embodiment of the present invention;

FIG. 6 is a map characteristic diagram showing a relationship between a deviation ΔN between target rotation speed data and actual rotation speed data and a control gain KI used in the first embodiment of the present invention.

FIG. 7 is a map characteristic diagram showing a relationship between a duty ratio of a drive signal and an ISC air amount QSSC used in the first embodiment of the present invention.

FIG. 8 is an explanatory diagram showing a duty ratio of a drive signal in FIG. 7;

[Explanation of symbols]

1 engine, 3 intake pipe, 4 throttle valve, 10
ISC bypass passage, 13 ISC solenoid valve (bypass air amount adjustment valve), 14 pressure sensor, 20
Control device, KI, -KI control gain, Ne engine speed, Nt target speed, Pb intake pipe pressure, QA,
QB Predetermined value (limit value), QISC ISC air amount (bypass air amount), QLRN learning value, S7 Step of detecting throttle valve open / close state, S9 Step of controlling idle speed, S95 Engine speed is target speed To determine that convergence has been achieved, S96
Storing a learning value, S98, comparing the engine speed with the target speed, S99 calculating a negative control gain, S100 comparing the control amount of reduction of the bypass air amount with the lower limit value, S101, S1.
06 setting the bypass air amount by the control gain, S102 clipping the reduction amount to the lower limit, S103 driving the bypass air amount adjustment valve, S104 calculating the positive control gain,
S105: a step of comparing the increase control amount of the bypass air amount with the upper limit value; and S107 a step of clipping the increase control amount to the upper limit value.

Claims (1)

[Claims] An intake pipe for supplying an air-fuel mixture to an engine; a throttle valve provided in the intake pipe for adjusting an engine intake amount; and an upstream and a downstream of the throttle valve so as to bypass the throttle valve. A bypass passage connected therebetween, a bypass air amount adjusting valve provided in the bypass passage to adjust a bypass air amount, a pressure sensor for detecting a pressure of the intake pipe, and an intake pipe detected from the pressure sensor A throttle valve open / closed state detecting means for detecting the open / closed state of the throttle valve based on pressure; and, when the throttle valve is in a closed state, controlling the bypass air amount adjusting valve to adjust the bypass air amount. An engine speed control means for causing the engine speed to converge to the target engine speed; Learning value storage means for storing a pass air amount as a learning value, wherein the engine speed control means reduces the bypass air amount when setting the bypass air amount when the throttle valve is in a closed state. In the case where the predetermined value is subtracted from the learned value, the bypass air amount is limited to a lower limit or more, and when the bypass air amount is increased, the value is set to be equal to or less than an upper limit obtained by adding a predetermined value to the learned value. An engine speed control device, wherein the amount of bypass air is limited.