JP2000045832A - Engine speed control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the engine speed controlling performance by providing a control means for setting a dead zone of the number of revolution in response to the opening position of an idle control valve. SOLUTION: When the idle control starting condition is satisfied, idle air unit changed amounts ΔQaup and ΔQadown in the case of gradually increasing or reducing the opening of an idle control valve by one step from the real opening position ISC POSI of the idle control valve are obtained (S302). Continuously, a real engine speed unit changed amount KNUP in relation to the idle air unit changed amounts ΔQaup and ΔQadown is obtained on the basis of an engine speed unit changed amount KNUP table of the intake pipe negative pressure Pb (S304). A number of revolution changed amount is computed by interpolating the engine speed unit changed amount KNUP with the idle air unit changed amounts ΔQaup and ΔQadown, and a dead zone hysteresis NHYS is added to the maximum value (max) of the number of revolution changed amount so as to set the number of revolution dead zone NDEAD (S306). With this structure, the number of revolution dead zone NDEAD having the minimum width along the flow characteristic of the idle control valve can be set.

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, and more particularly, to setting a speed dead zone corresponding to a flow rate characteristic of an idle control valve to improve controllability of the engine speed. The present invention relates to an engine speed control device that can be realized by changing a program without requiring additional components and can be implemented at low cost.

[0002]

2. Description of the Related Art Some engines mounted on a vehicle are provided with an engine speed control device in order to control the engine speed during idle operation to a target speed. The engine speed control device includes an idle air passage that bypasses a throttle valve in an intake passage of the engine, an idle control valve (ISC valve) that adjusts an idle air amount in the idle air passage, and an engine that controls the engine by using the idle control valve. Control the speed.

When the control is started (step 500), as shown in FIG.
It is determined whether an idle control start condition is satisfied (step 502). The idle control start condition is that the state in which the throttle valve is in the idle opening state by turning on the idle switch continues for XTINHFB time or more, the vehicle stops, and the absolute difference between the engine speed Ne and the target speed N _TRGET is determined. The value exceeds the rotational speed dead band N _DEAD (| Ne
−N _TRGET |> N _DEAD ), it is determined to be satisfied.

If this determination (step 502) is NO, this determination (step 502) is repeated. If this determination (step 502) is YES, it is determined whether or not the engine speed Ne is _{equal to} or higher than the target speed N _TRGET (step 504).

[0005] When the determination (step 504) is YES, one sampling period before the rotational speed feedback air quantity Q _NFBO subtracts the rotational speed feedback integral correction value K _I seeking rotational speed feedback air quantity Q _NFB ( Q
_NFB = Q _NFBO -K _I) (step 506), the process returns to the determination (step 502).

If this determination (step 504) is NO, the rotational speed feedback air amount Q _NFB is obtained by adding the rotational speed feedback integral correction value K _I to the rotational speed feedback air amount Q _NFBO one sampling period ago ( Q _NFB
= Q _NFBO + K _I ) (step 508), and return to the judgment (step 502).

The engine speed control device obtains an idle air amount Q _ISC from the obtained rotation speed feedback air amount Q _NFB and the basic idle air amount Q _BASE, and _{converts the} idle air amount Q _ISC to the idle control shown in FIG. The actual opening position ISC of the idle control valve is converted by the conversion map.
Seeking P _OSI, by changing the opening position of the opening position ISC P _OSI idle control valve, the idle air quantity Q _ISC
, The feedback control is performed such that the engine speed Ne becomes the target speed N _TRGET when the idle control start condition is satisfied.

[0008] idle control valve varies the opening degree position ISC P _OSI idle air passage closing direction when the actual engine speed Ne to the target rotational speed N _TRGET high relative to the target rotational speed N _TRGET Thus, when the actual engine speed Ne is low, the opening degree position ISC P _OSI is controlled to change in a direction to open the idle air passage.

At this time, the opening position ISC P _{OS I} is moved by one step (1
When the idle air unit change amount ΔQ _ISC which is a change amount of the idle air amount Q _{ISC with} respect to the change of the opening position ISC P _OSI per step is large as in the case of an idle control valve which is changed by the When the engine speed Ne is controlled so as to faithfully follow the engine speed N _TRGET , as shown in FIG.
The SC P _OSI changes frequently, and the idle air amount Q _ISC increases and decreases frequently, and there is a problem that the engine speed Ne fluctuates with respect to the target speed N _TRGET .

For this reason, in the engine speed control device, as shown in FIG. 15, a speed dead zone N _DEAD having a certain width is set on the high side and the low side with respect to the target speed N _TRGET , and feedback control is performed. When the engine speed Ne is _within the speed dead zone N _DEAD of the target speed N _TRGET , the opening position ISC P _OSI of the idle control valve is controlled to _remain unchanged.

During idle operation with no load, the engine speed Ne fluctuates greatly with respect to the engine intake air amount. Therefore, as shown in FIG. Different idle air unit change amounts ΔQ _ISC 1 and ΔQ _ISC 2 are provided by setting the flow characteristics, and when the idle air amount Q _ISC is low, small idle air unit change amount ΔQ _ISC 1 enables fine flow rate adjustment. On the other hand, when the idle air amount Q _ISC is a high flow rate, there is a type that enables quick flow rate adjustment as a large idle air unit change amount ΔQ _ISC 2.

[0012] Such an engine speed control device is disclosed in Japanese Patent Application Laid-Open No. Hei 7-103442 or Japanese Patent Application Laid-Open No. 8-338.
No. 281 is disclosed.

Japanese Patent Application Laid-Open No. Hei 7-103442 discloses that the opening characteristic of an idle speed control valve has a large opening change in a high opening region from a low opening region with an inflection point set in advance as a boundary. The number of steps (the number of steps) is set, and the number of basic steps and the number of virtual steps are corrected by the correction amount set as the number of steps of the same form. If the corrected number of virtual steps is smaller than the inflection point, The actual number of steps is set as the actual number of steps, and if it is larger than the inflection point, the excess is corrected by the ratio of the amount of change in the opening to obtain an appropriate number of actual steps in consideration of the opening characteristics of the idle speed control valve. .

Japanese Patent Application Laid-Open No. 8-338281 discloses an auxiliary air control amount such that when the accelerator depression amount detected by the accelerator position sensor is zero, the engine speed detected by the distributor becomes a predetermined value. And outputs the target opening calculated based on the auxiliary air control amount to the throttle actuator,
This controls the throttle opening.

[0015]

By the way, as described above, the engine speed control device includes the target engine speed N _TRGET.
The rotational speed dead zone N of a certain width ranging from the high side to the low side
_{If the} engine speed Ne is _within the speed dead zone N _DEAD of the target speed N _TRGET during the feedback control during the feedback control, the opening position ISC P _OSI of the idle control valve is set.
Some are controlled so as to be kept unchanged.

However, the width of the rotational speed dead zone N _DEAD of the target rotational speed N _TRGET is equal to the idle air unit change amount ΔQ corresponding to the change in the opening position per one step of the idle control valve.
_It is necessary to set the engine speed Ne to be within the speed dead zone N _DEAD even at the point where the _ISC changes most.

In particular, as shown in FIG. 16, the flow characteristic of the idle control valve is not linear, and is set to a flow characteristic in which the idle air unit change amounts ΔQ _ISC1 and ΔQ _ISC 2 are different at the inflection point P as a boundary. and if that, since the engine speed Ne even at high flow rate region to be large idle air unit variation Delta] Q _ISC 2 needs to be set to fit the rotational speed deadband N _DEAD, the rotational speed deadband N _DEAD As shown in FIG. 17, the width of the rotational speed dead zone N _DEAD in the low flow rate region where the idle air unit change amount ΔQ _ISC 1 becomes small as shown in FIG. 17 increases, and the target rotational speed of the engine rotational speed Ne increases. There is a disadvantage that the controllability to the number N _TRGET is deteriorated.

[0018]

SUMMARY OF THE INVENTION In order to eliminate the above-mentioned disadvantages, the present invention provides an idle air passage which bypasses a throttle valve in an intake passage of an engine mounted on a vehicle. An idle control valve for adjusting the air amount is provided, and when the idle control start condition is satisfied, the opening position of the idle control valve is changed to perform feedback control so that the engine speed reaches the target speed, and during this feedback control, When the engine speed is within a speed dead zone of a target speed, an engine speed control device that controls the opening position of the idle control valve to be maintained without changing the opening position of the idle control valve. Control means is provided for controlling to set the rotational speed dead zone according to the position.

The control means obtains an idle air unit change amount when the opening position of the idle control valve is changed by one unit, and obtains an engine speed unit change amount with respect to the idle air unit change amount. The rotation speed dead zone is controlled in accordance with the amount of change in the engine rotation speed unit, and the control means changes the flow characteristic of the idle control valve at least at one inflection point as a boundary. The system is characterized in that it is provided so as to be set to the idle air unit change amount, and is controlled so as to set the rotational speed dead zone in accordance with the idle air unit change amount set differently.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An engine speed control apparatus according to the present invention is characterized in that the control means controls a flow rate characteristic of an idle control valve by performing control so as to set a speed dead zone in accordance with an opening position of the idle control valve. A corresponding rotational speed dead zone can be set.

For example, the amount of change in idle air unit when the opening position of the idle control valve is changed by one unit is obtained,
An engine speed unit change amount with respect to the idle air unit change amount is obtained, and control is performed so as to set a rotation speed dead zone in accordance with the engine speed unit change amount. It is possible to set a narrow rotational speed dead zone, greatly improve the controllability of the engine rotational speed, or to change the flow characteristic of the idle control valve to at least one inflection point as a different idle air unit change amount. By controlling the setting so that the rotational speed dead zone is set in accordance with the idle air unit change amount of the different setting, it is possible to set the rotational speed dead zone corresponding to the flow rate characteristic of the idle control valve. The software can be simplified as compared with the case where the rotational speed dead zone is set in accordance with the engine rotational speed unit change amount.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 7 show a first embodiment of the present invention. 7, reference numeral 2 denotes an engine mounted on a vehicle (not shown), 4 denotes a piston, 6 denotes a combustion chamber, 8 denotes an intake valve, and 10 denotes an exhaust valve.

The engine 2 is provided with an intake passage 22 communicating with the combustion chamber 6 by sequentially connecting an air cleaner 12, an intake pipe 14, a throttle body 16, a surge tank 18, and an intake manifold 20 as an intake system. A throttle valve 24 is provided in the intake passage 22 of the throttle body 16. Further, the engine 2 is provided with an exhaust passage 32 communicating with the combustion chamber 6 by sequentially connecting an exhaust manifold 26, a catalytic converter 28, and an exhaust pipe 30 as an exhaust system. Reference numeral 34 denotes a first blow-by gas pipe, 36 denotes a second blow-by gas pipe, and 38 denotes a PCV valve.

The engine 2 has an exhaust manifold 26
One end communicates with an EGR inlet 40 provided in the exhaust passage 32, and an EGR passage 44 which communicates the other end with an EGR recirculation port 42 provided in the intake passage 22 of the intake manifold 20 is provided. In the middle of the EGR passage 44, the EGR
A control valve 46 is provided.

The EGR control valve 46 is connected to the surge tank 18 via an EGR control pressure passage 50 by an EGR operation valve 48.
Of the intake passage 22 of the EG as a control pressure,
The opening and closing of the R passage 44 is controlled so that a part of the exhaust gas is
2 to the intake passage 22.

The engine 2 has a fuel injection valve 52 provided in the intake manifold 20 so as to be directed toward the combustion chamber 6. The fuel injection valve 52 is connected to the fuel tank 5 by the fuel supply passage 54.
6 has been contacted. A fuel pump 58 that supplies fuel to the fuel supply passage 54 is provided in the fuel tank 56. A fuel filter 60 is provided in the middle of the fuel supply passage 54.

In the middle of the fuel supply passage 54, a fuel pressure adjusting mechanism 62 is provided. Fuel pressure adjusting mechanism 62
The pressure of the intake passage 22 of the surge tank 18 is acted as an adjustment pressure by the adjustment pressure passage 64, the fuel pressure is adjusted to a predetermined pressure, and excess fuel is returned to the fuel tank 56 by the fuel return passage 68.

A purge passage 70 is provided in the fuel tank 56.
Communicates with one end of the The other end of the purge passage 70 is
It is communicated with the canister 72. A two-way valve 74 is provided in the middle of the purge passage 70. One end of the evaporation passage 176 communicates with the canister 72. The other end of the evaporative passage 76 is connected to the throttle body 16.
Is connected to the intake passage 22.

The engine 2 has an idle air passage 78 which bypasses the throttle valve 24 and communicates with the intake passage 22 of the throttle body 16 and the intake passage 22 of the surge tank 18. Idle control valve (ISC valve) 8 for adjusting air volume
0 is provided. The idle control valve 80 moves the opening position by one step (one unit) by a step motor type or duty solenoid type actuator (not shown).
The idle air volume is adjusted in steps.

The engine 2 has an ignition coil 84 and a distributor 86 which constitute an ignition mechanism 82.
Are provided. The distributor 86 is provided with a crank angle sensor 88 that functions as a rotation speed sensor by detecting not only the crank angle but also the engine speed.

The engine 2 is provided with an intake pressure sensor 92 for detecting the intake pressure introduced from the intake passage 22 of the surge tank 18 through the detection pressure passage 90, and a water temperature sensor for detecting the temperature of the cooling water of the engine 2. 94, an throttle sensor 96 for detecting the throttle opening of the throttle valve 24, an intake air temperature sensor 98 for detecting the intake air temperature in the intake passage 22, and an O2 sensor for detecting the oxygen concentration in the exhaust gas in the exhaust gas passage 32. 100 and a vehicle speed sensor 102 for detecting the vehicle speed of the vehicle.

The EGR operation valve 48, the fuel injection valve 52, the fuel pump 58, the idle control valve 80, the ignition coil 84, the crank angle sensor 88, the intake pressure sensor 92, the water temperature sensor 94, the throttle sensor 96, the intake temperature sensor 98, The O2 sensor 100 and the vehicle speed sensor 102 are connected to control means 106 constituting an engine speed control device 104.

A thermo fuse 108 attached to the catalytic converter 28 is connected to the control means 106 via a warning lamp 110.
A battery 116 is connected via the fuse 12 and the fuse 114.

The engine speed control device 104 controls the sensors 88, 92 to 10 through control means 106.
The operation state of the engine 2 is detected based on a signal input from the engine 2, and the engine speed Ne is controlled by the idle control valve 80.

That is, the engine speed control device 104
As shown in FIG. 4, when the control starts (step 20).
0), it is determined whether an idle control start condition is satisfied (step 202). The idle control start conditions are as follows: a state in which the throttle valve 24 is set to the idle opening degree by the throttle sensor 96 continues for XTINHFB time or more, the vehicle is stopped by the vehicle speed sensor 102, and the engine speed Ne and the target rotation speed are determined by the crank angle sensor 88. Number N _TRGET
The absolute value of the difference from the value exceeds the rotational speed dead band N _DEAD (|
Ne−N _TRGET |> N _DEAD ), it is determined to be satisfied.

If this determination (step 202) is NO, this determination (step 202) is repeated. If this determination (step 202) is YES, it is determined whether or not the engine speed Ne is _{equal to} or higher than the target speed N _TRGET (step 204).

If the determination (step 204) is YES, the rotational speed feedback integral correction value K _I is subtracted from the rotational speed feedback air amount Q _NFBO one sampling period before to obtain the current rotational speed feedback air amount Q _NFB . _Obtained (Q _NFB = Q _NFBO -K _I ) (step 206) and judge (return to step 202).

If the determination (step 204) is NO, the rotational speed feedback integral correction value K _I is added to the rotational speed feedback air amount Q _NFBO one sampling cycle before to make the current rotational speed feedback air amount Q _NFB . (Q _NFB = Q _NFBO + K _I ) (step 208), and return to the decision (step 202).

The engine speed control device 104 obtains the idle air amount Q _ISC from the obtained speed feedback air amount Q _NFB and the basic idle air amount Q _BASE, and this idle air amount Q _ISC is shown in FIG. The actual opening position ISC P _OSI of the idle control valve 80 is obtained by conversion using the idle control conversion map.
By changing the opening position of the idle control valve 80 to _OSI , the idle air amount Q _ISC is adjusted.

As described above, the engine speed control device 10
4, at the time of establishment of the idle control start condition, the opening position ISC P _OSI idle control valve 80 by changing a feedback control so that the engine rotational speed Ne reaches the target rotational speed N _TRGET.

The engine speed control device 104
As shown in FIG. 5, a rotational speed dead zone N _DEAD having a certain width on each of the high side and the low side with respect to the target rotational speed N _TRGET is set. Thereby, the engine speed control device 104
Is the engine speed Ne by the idle control valve 80.
During the feedback control, when the engine speed Ne is _within the speed dead zone N _DEAD of the target speed N _TRGET , the opening degree position ISC P _OSI of the idle control valve 80 is controlled to be kept unchanged.

Further, as shown in FIG. 6, the idle control valve 80 whose opening degree position is changed by one step (one unit) by the step motor type actuator or the like has its flow rate characteristic bounded at the inflection point P as shown in FIG. The flow rate characteristics are set to be different idle air unit change amounts ΔQ _ISC 1 and ΔQ _ISC 2. This allows the engine speed control device 104 to finely adjust the flow rate as a small idle air unit change amount ΔQ _ISC 1 when the idle air amount Q _ISC is a low flow rate, while the idle air amount Q _ISC is high. thereby enabling rapid flow rate adjustment as a large idling air unit variation Delta] Q _ISC 2 when the flow rate.

The engine speed control device 104 controls the control means 106 to set the speed dead zone N _DEAD according to the opening position ISC P _OSI of the idle control valve 80.

The engine speed control device 10 of the first embodiment
Reference numeral 4 denotes an idle air unit change amount ΔQaup when the opening degree position ISC P _OSI of the idle control valve 24 is changed by one step (one unit) as an idle air unit change amount ΔQ _ISC and a decrease change. The amount of change in idle air unit ΔQdown at this time is determined, the amount of change in engine speed unit KNUP with respect to the amount of change in idle air unit ΔQup · ΔQdown is obtained, and the rotational speed dead band N _{DEAD is} determined according to the amount of change in engine speed unit KNUP. Is controlled to be set.

Next, the operation of the first embodiment will be described.

The engine speed control device 104 changes the opening position ISC P _OSI of the idle control valve 80 when the idling control start condition is satisfied by the control means 106 so that the engine speed Ne becomes the target speed N _TRGET. When the engine speed Ne falls _within the speed dead zone N _DEAD of the target speed N _TRGET during the feedback control of the engine speed Ne by the idle control valve 80, the idle control valve 80 Is controlled to be maintained without changing the opening position ISC P _OSI of.

At this time, the engine speed control device 104
Controls to set the rotational speed dead zone N _DEAD according to the opening position ISC P _OSI of the idle control valve 80.

As shown in FIG. 1, when the program is started by the control means 106 (step 300), the engine speed control device 104 performs one step (one unit) from the current opening position ISC P _OSI of the idle control valve 80. ), The idle air unit change amount ΔQaup when the increase and the idle air unit change amount ΔQdown when the decrease is changed (step 302).

Next, this idle air unit change amount ΔQa
The current engine rotational speed unit change amount KNUP with respect to up · ΔQdown is represented by KNU of intake pipe negative pressure Pb shown in FIG.
It is determined from the P table (step 304).

The idle air unit variation ΔQ
The engine speed change amount KNUP is interpolated by using aup · ΔQdown to calculate the engine speed change amount, and the maximum value max of the engine speed change amount is set to the dead zone hysteresis NH.
YS is added to set the rotational speed dead zone N _DEAD .

As described above, in the engine speed control device 104 of the first embodiment, the idle air when the opening position ISC P _OSI of the idle control valve 80 is changed by the step (one unit) by the control means 106. Unit change amount ΔQa
Up · ΔQdown is obtained, an engine speed unit change amount KNUP with respect to the idle air unit change amount ΔQup · ΔQdown is obtained, and control is performed such that the engine speed dead zone N _DEAD is set in accordance with the engine speed unit change amount KNUP. As shown in FIG. 3, the minimum rotational speed dead zone N _DEAD can be set in accordance with the flow characteristics of the idle control valve 80.

Therefore, the engine speed control device 1
04 can set the minimum width of the rotational speed dead zone N _DEAD in accordance with the flow rate characteristic of the idle control valve 80, thereby greatly improving the controllability of the engine rotational speed Ne and simplifying the software. It can be realized by changing the program without requiring additional components, and can be implemented at low cost.

FIGS. 8 and 9 show a second embodiment of the present invention. Engine speed control device 1 of second embodiment
No. 04 sets and sets the flow characteristics of the idle control valve 80 to be different idle air unit change amounts ΔQ _ISC, and sets the rotational speed dead zone N _DEAD in accordance with the different set idle air unit change amounts ΔQ _ISC. ing.

That is, as shown in FIG. 6, the engine speed control device 104 of the second embodiment changes the flow rate characteristics of the idle control valve 80 to different idling air unit changes ΔQ _{ISC at} one inflection point P as a boundary. The opening position ISC of the idle control valve 24 is set and provided with a flow rate characteristic of 1.ΔQ _ISC 2.
Idle air unit variation Δ set differently depending on P _OSI
Revolution speed dead zone XND according to Q _ISC 1 and ΔQ _ISC 2
EADL / XNDEADH is set.

Next, the operation of the second embodiment will be described.

When the idling control start condition is satisfied by the control means 106, the engine speed control device 104
As described above, the opening position ISCP of the idle control valve 80
_The engine speed Ne is changed to the target speed N by changing the _OSI.
The feedback control is performed so as to _{attain TRGET,} and during the feedback control of the engine speed Ne by the idle control valve 80, when the engine speed Ne falls _within the speed dead zone N _DEAD of the target speed N _TRGET , the idle control valve The opening degree position ISC P _OSI of 80 is controlled to be kept unchanged.

At this time, the engine speed control device 104
Indicates that the flow characteristic of the idle control valve 80 is different from the idle air unit change amount ΔQ _ISC 1 ·
Provided by setting the flow rate characteristic as a Delta] Q _ISC 2, respectively rpm dead zone XNDEADL · XNDEADH in accordance with the opening degree position ISCP idle air unit variation in different settings by _OSI ΔQ _ISC 1 · ΔQ _ISC 2 idle control valve 80 Control to set.

As shown in FIG. 8, when the program is started by the control means 106 (step 400), the current opening position ISC P _OSI of the idle control valve 24 is changed to the dead zone switching opening position, as shown in FIG. X
Whether or not NCHGP is exceeded (ISC P _OSI > XN
CHGP) is determined (step 402).

If the determination (step 402) is YES, the rotational speed dead zone N _{DEAD is set} to a large value.
Set to NDEADH (N _DEAD = XNDEADH)
(Step 404).

Next, whether or not the present opening position ISC P _OSI of the idle control valve 80 is equal to or less than a value obtained by subtracting the dead band switching opening hysteresis XNCHGHS from the dead band switching opening position XNCHGP (ISC P _OSI ≤ XNCHGP)
-XNCGHHS) is determined (step 406).

If the determination (step 406) is YES, the rotational speed dead zone N _{DEAD is changed} to the rotational speed dead zone X having a small width.
NDEADL is set (N _DEAD = XNDEADL) (step 408), and the process returns to the determination (step 402).

On the other hand, if this determination (step 406) is NO
In this case, the process returns to the process (step 404). If the determination (step 402) is NO, the rotational speed dead zone N _{DEAD is set} to a small value of the rotational speed dead zone XN.
DEADL is set, and the process returns to the determination (step 402).

As described above, in the engine speed control device 104 of the second embodiment, the control means 106 controls the flow characteristic of the idle control valve 80 to change the idling air unit variation ΔQ different from each other at one inflection point P as a boundary. The idle control valve 24 is set and provided to have a flow rate characteristic of _ISC 1 · ΔQ _ISC 2.
Rotational speed deadband XNDEADL · XND in opening position ISC P idle air unit variation ΔQ _ISC 1 · ΔQ _ISC 2 respectively two different width according to different settings by _OSI
By setting EADH, it is possible to set a rotational speed dead zone N _DEAD having a width corresponding to the flow rate characteristic of the idle control valve 80.

For this reason, the engine speed control device 104 of the second embodiment can improve the controllability of the engine speed Ne, improve the controllability of the engine speed Ne, and increase the number of additional components. It can be realized by changing the program without the need, and moreover, the rotational speed dead zone XNDEA of two different widths
By controlling to switch to DL / XNDEADH, software can be simplified as compared with the case where the rotational speed dead zone N _DEAD is set in accordance with the engine rotational speed unit change amount KNUP as in the above-described embodiment. It can be implemented at low cost.

FIG. 10 shows a third embodiment SG1 of the present invention. The engine speed control device 104 according to the third embodiment changes the flow characteristic of the idle control valve 80 by changing the idling air unit change amount ΔQ at one inflection point P as a boundary.
_In the region below the inflection point P where the idle air flow rate Q _ISC is a low flow rate and the small idle air unit change amount ΔQ _ISC 1 is set and provided at a flow rate characteristic of _ISC 1 · ΔQ _ISC 2 at low opening. The rotational speed dead zone XNDADELG which gradually decreases and changes from the minimum value of the dead zone settable rotational speed is set, and the inflection point P where the idle air flow rate Q _ISC is a high flow rate and the idle air unit change amount ΔQ _ISC 2 becomes large. In the region where the rotation speed is high, the rotation speed dead zone XNDEADHG is set to gradually decrease from the minimum value of the rotation speed at which the dead zone can be set at the high opening.

As described above, the engine speed control device 104 according to the third embodiment has a small idle air unit variation ΔQ.
_In the region below the inflection point P where _ISC 1 is set, the rotational speed dead zone XNDADELG which gradually decreases and changes is set, and in the region beyond the inflection point P where the large idle air unit change amount ΔQ _ISC 2 is obtained. By controlling the rotational speed dead zone XNDEADHG to be set to the rotational speed dead zone XNDEADHG, the idle control valve 80 is controlled in each of the regions where the inflection point P is a boundary and the idle air unit change amounts ΔQ _ISC 1 and Q _ISC 2 are different. The rotation speed dead zone N _DEAD having a width corresponding to the flow rate characteristics can be set.

For this reason, the engine speed control device 104 of the third embodiment can improve the controllability of the engine speed Ne, improve the controllability of the engine speed Ne, and increase the number of additional components. This can be realized by changing the program without any need, and the rotation speed dead zone N _DEAD which is narrower than in the second embodiment can be set.

FIG. 11 shows a fourth embodiment SG2 of the present invention. The engine speed control device 104 according to the third embodiment changes the flow characteristic of the idle control valve 80 by changing the idling air unit change amount ΔQ at one inflection point P as a boundary.
_In the region below the inflection point P where the idle air flow rate Q _ISC is a low flow rate and the small idle air unit change amount ΔQ _ISC 1 is set and provided at a flow rate characteristic of _ISC 1 · ΔQ _ISC 2 at low opening. The rotation speed dead band XNDEADS is set so as to gradually increase from the minimum value of the rotation speed at which the dead zone can be set to the minimum value of the rotation speed at the time of high opening, and the idle air flow rate Q _ISC is high and the idle air unit is large. In a region beyond the inflection point P where the change amount ΔQ _ISC 2 is obtained, a certain rotation speed dead zone XNDEA based on the minimum value of the rotation speed at which the dead zone can be set at the time of the high opening degree.
DH is set.

As described above, the engine speed control device 104 of the fourth embodiment provides a small idle air unit variation ΔQ
_In the region below the inflection point P where _ISC 1 is set, the rotational speed dead zone XNDEADS is set to increase and the inflection point P where the large idle air unit change amount ΔQ _ISC 2 is set.
In the region beyond, a certain rotational speed dead zone XNDEA
By controlling to set to DH, it is possible to prevent the width of the rotational speed dead zone N _{DEAD from} becoming unnecessarily large in the area of the small idle air unit change amount ΔQ _ISC 1, and to make the large idle air unit change amount ΔQ _ISC 2 Can set a small width rotation speed dead zone N _DEAD .

For this reason, the engine speed control device 104 of the fourth embodiment provides a small idle air unit variation ΔQ
While avoiding deterioration of the controllability of the engine speed Ne in the region of _ISC 1, a large idle air unit variation ΔQ
The controllability of the engine speed Ne in the region of _ISC 2 can be secured, the controllability of the engine speed Ne as a whole can be improved, and the controllability of the engine speed Ne can be improved,
This can be realized by changing the program without requiring additional components.

[0071]

As described above, the engine speed control apparatus according to the present invention controls the setting of the speed dead zone in accordance with the opening position of the idle control valve, thereby coping with the flow rate characteristics of the idle control valve. A rotation speed dead zone can be set.

For this reason, the engine speed control device can improve the controllability of the engine speed by setting the speed dead zone corresponding to the flow characteristic of the idle control valve, and can increase the number of additional components. It can be realized by changing the program without need, and can be implemented at low cost.

[Brief description of the drawings]

FIG. 1 is a flowchart for setting a rotational speed dead zone of an engine rotational speed control device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a table of an engine speed unit change amount;

FIG. 3 is a diagram showing setting of a rotational speed dead zone with respect to an idle air unit change amount.

FIG. 4 is a flowchart of engine speed control.

FIG. 5 is a diagram showing a relationship between a target rotational speed in which a rotational speed dead zone is set, an opening position of an idle control valve, and an idle air amount.

FIG. 6 is a diagram illustrating flow characteristics of an idle control valve in which different amounts of change in idle air unit are set at inflection points as boundaries.

FIG. 7 is a schematic configuration diagram of an engine speed control device.

FIG. 8 is a flowchart for setting a rotational speed dead zone according to a second embodiment of the present invention.

FIG. 9 is a diagram showing a setting of a rotational speed dead zone with respect to an idle air unit change amount.

FIG. 10 is a view showing a setting of a rotational speed dead zone with respect to an idle air unit change amount according to a third embodiment of the present invention.

FIG. 11 is a diagram showing a setting of a rotational speed dead zone with respect to an idle air unit change amount according to a fourth embodiment of the present invention.

FIG. 12 is a flowchart of engine speed control according to a conventional example.

FIG. 13 is a diagram showing a conversion map for obtaining an actual opening position of an idle control valve from an idle air amount.

FIG. 14 is a diagram illustrating a relationship among a target rotation speed, an opening position of an idle control valve, and an idle air amount.

FIG. 15 is a diagram showing a relationship between a target rotational speed in which a rotational speed dead zone is set, an opening position of an idle control valve, and an idle air amount.

FIG. 16 is a diagram showing flow characteristics of an idle control valve in which different amounts of change in idle air unit are set at the inflection point as boundaries.

FIG. 17 is a diagram showing setting of a rotational speed dead zone for different amounts of change in idle air unit.

[Explanation of symbols]

 2 Engine 22 Intake passage 24 Throttle valve 32 Exhaust passage 78 Idle air passage 80 Idle control valve 88 Crank angle sensor 92 Intake pressure sensor 94 Water temperature sensor 96 Throttle sensor 98 Intake temperature sensor 100 O2 sensor 102 Vehicle speed sensor 104 Engine speed control device 106 Control means

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) G05B 11/36 501 G05B 11/36 501P F term (Reference) 3G084 BA03 BA06 CA03 DA04 EA12 EB11 FA02 FA05 FA11 FA20 FA29 FA33 FA38 3G301 HA01 HA13 JA00 JA04 KA07 LA04 ND01 NE25 PA07Z PA10Z PA15Z PD03Z PE01A PE01Z PE02Z PE03Z PE08Z PF01Z 5H004 GA34 GB12 HA08 HB07 HB08 JA03 KA44 KA45 MA21

Claims (3)

[Claims] An idle air passage bypassing a throttle valve is provided in an intake passage of an engine mounted on a vehicle, and an idle control valve is provided for adjusting an amount of idle air in the idle air passage. By changing the opening position of the idle control valve to perform feedback control so that the engine speed becomes the target speed, and during the feedback control, when the engine speed is in the speed dead zone of the target speed, In an engine speed control device for controlling the opening position of the idle control valve to be maintained without change, control means for controlling the rotation speed dead zone in accordance with the opening position of the idle control valve is provided. An engine speed control device characterized by the above-mentioned. 2. The control means calculates an idle air unit change amount when the opening position of the idle control valve is changed by one unit, and obtains an engine speed unit change amount with respect to the idle air unit change amount. 2. The engine speed control device according to claim 1, wherein control is performed to set the rotation speed dead zone in accordance with the amount of change in the engine speed unit. 3. The control device according to claim 1, wherein the flow rate characteristic of the idle control valve is set so as to have different idle air unit change amounts at least at one inflection point as a boundary. 2. The engine speed control device according to claim 1, wherein control is performed to set the rotation speed dead zone in accordance with the amount.