JPH08144821A - Idle engine speed controller for engine - Google Patents

Abstract

PURPOSE: To eliminate worsening in combustion stability during idling, which accompanies the lowering in a pump loss at highlands where the density of intake air is smaller than that at lowlands, by determining an intake air flow to obtain a prescribed engine speed based on the air density at highlands in order to control the ignition timing through feedback of the air flow. CONSTITUTION: In a controller, an idle engine speed control valve 9 is interposed in a bypass passage 8, which is prepared so as to make a detour round a throttle valve 4, and, during the idling control in highlands, engine load conditions corresponding to working states of the load in an air conditioner or a power steering device are decided. The atmospheric pressure is read based on a detection signal of an air-flow meter, while an engine speed is read based on an ignition signal on an ignition device 32. During the idling operation, the amount of correction for ignition timing is read based on both atmospheric pressure Pa and an ignition timing correction table. The final ignition timing at highlands is determined by deducting the amount of correction from the ignition timing corresponding to the engine load condition at that time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine idle speed control system, and more particularly to an engine idle speed control system when the air density is lower than in a steady state.

[0002]

2. Description of the Related Art Conventionally, in an idle speed control device for an engine, an idle speed control valve (hereinafter referred to as IS) provided so as to bypass a throttle control valve.
(Abbreviated as C) is used to control the idle speed to be kept constant. This ISC operates the engine at the best idle speed by controlling the ISC during idle when the throttle valve control is in the fully closed state, and executes the throttle control slightly when the vehicle speed exceeds a predetermined value. In this way, the ISC air flow rate is reduced from that at the time of idling, and when the vehicle speed falls below a predetermined value, the throttle control is released to prepare for the control of the idling speed.

[0003] Even if the car is driven in a high altitude such as a mountainous area with a high altitude, the ISC corrects the air flow rate of the ISC in accordance with the atmospheric pressure in the environment to correct the engine pressure. Is controlled so that even in a highland where the air density is low, the idling operation can be performed at the same rotation speed as in the lowland where the altitude is low. On the other hand, when the idling speed control is performed as in the conventional case, the load (hereinafter abbreviated as pumping loss) applied to the engine for generating intake negative pressure is reduced at high altitudes and the idling operation is performed at low altitudes due to the following reasons. It becomes possible to carry out with a lighter load (small air filling amount).

(Reason for Reduction of Pumping Loss) At high altitudes, the atmospheric pressure is reduced, so that the air density is reduced. → It is necessary to increase the intake air volume (volume flow rate) in order to operate at the same idling speed as in lowlands under low air density conditions. → IS by atmospheric pressure correction, F / B correction of idle speed
The air flow rate (volume flow rate) of C increases.

→ In order to operate at the same idling speed as in the lowland, the intake negative pressure becomes low in the highland. → The pumping loss of the engine is reduced. → Operates at the same idling speed as in the lowlands at high altitudes with a small air charge (low mass flow rate).

As the conventional idle speed control device as described above, for example, as disclosed in Japanese Utility Model Laid-Open No. 3-114555, the idle speed is controlled when the intake negative pressure becomes lower than a set value. Is controlled to be high to increase the intake negative pressure (change to the side opposite to the atmospheric pressure side), thereby securing a large negative pressure actuator operating force and normally executing various control means without malfunction. Something like that is proposed.

[0007]

However, in the conventional example configured as described above, the F / B control taking into account the decrease in the pumping loss is not performed by the ISC, and therefore the following two problems occur. Was occurring. That is, from the standpoint of idle stability, when the pumping loss decreases and the air charge decreases, the compression pressure in the cylinder decreases. Therefore, the combustion stability during idling deteriorates as the pumping loss decreases (lighter load). Especially, in a vehicle with low idle stability such as a high output vehicle,
It causes rough idol and off idol.

From the viewpoint of the atmospheric pressure correction by ISC, the atmospheric pressure correction by ISC is usually the theoretical air-fuel ratio (λ =
The correction amount is determined based on 1), and the fact that the air filling amount decreases with the pumping loss is not taken into consideration. Therefore, if the normal F / B control is performed, the mass flow rate will be corrected to be the same as the mass flow rate in the lowland, so the volumetric flow rate and the fuel will increase due to the lower air density, and the idling speed will increase from the lowland However, the reference value of F / B control by ISC will be displaced. This results in reducing the allowable margin in the F / B control (difference between the upper limit value and the reference value in the F / B control).

Therefore, the engine idle speed control device of the present invention has been made in view of the above circumstances, and its purpose is to improve the combustion stability during idling due to a decrease in pump loss at high altitudes. It is an object of the present invention to provide an engine idle speed control device capable of eliminating deterioration and improving idle stability of a high-power vehicle in particular.

Another object of the present invention is to provide an engine idle speed control device which can prevent a reduction in the allowable margin of F / B control due to a decrease in pump loss and realize stable F / B control.

[0011]

In order to solve the above problems and achieve the object, an engine idle speed control device of the present invention has the following configuration. That is, in an engine idle speed control device for controlling the intake air amount to control the engine idle speed to a predetermined speed, the intake air density in the highlands is lower than the intake air density in the highlands. Means for determining the value of the intake air amount for obtaining the predetermined rotation speed based on the above, and an F / B control that is controlled on the basis of the value of the intake air amount so that the engine maintains the predetermined rotation speed. And means.

Also, preferably, in an engine idle speed control device for controlling an intake air amount for controlling an engine idle speed to a predetermined speed, in an altitude where intake air is lower than a lowland air density. A high altitude correction means for determining a value of a first intake air amount based on a theoretical value to obtain the predetermined rotation speed, and a second from the value of the first intake air amount based on an air density of the high altitude. Means for determining the value of the intake air amount, and F / B control means for controlling the engine so as to maintain the predetermined rotation speed on the basis of the value of the second intake air amount. Characterize.

Also, preferably, in an engine idle speed control device for controlling an intake air amount in order to control an engine idle speed to a predetermined speed, the intake air is controlled at a high altitude lower than an air density at a low altitude. A means for determining a value of an intake air amount for obtaining the predetermined rotation speed based on the air density of the highland, and an air-fuel ratio in the highland based on the air density of the highland from an air-fuel ratio in the lowland. And a control means for controlling in the rich direction.

Preferably, in an engine idle speed control device for controlling an intake air amount for controlling an engine idle speed to a predetermined speed, the intake air is controlled at a high altitude lower than an air density at a low altitude. A means for determining a value of an intake air amount for obtaining the predetermined rotation speed based on the air density of the highland, and an ignition timing in the highland based on the air density of the highland from an ignition timing in the lowland. And a control means for controlling the delay direction.

[0015]

As described above, since the engine idle speed control device according to the present invention is configured, by delaying the ignition timing at the time of idling, the combustion efficiency is lowered and the air charge amount is increased. The stability can be improved.

By setting the fuel increase rate at the time of idling to be high, the combustion efficiency is lowered, so that the idling stability can be improved. By controlling the duty of the ISC so as to subtract the volume flow volume that became a light load due to pumping loss from the volume flow volume that was excessively supplied by atmospheric pressure correction in the conventional ISC, the standard of F / B control by ISC It is possible to prevent the values from shifting.

[0017]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It is a schematic block diagram of the engine idle speed control device of the Example based on this invention. In FIG. 1, the intake passage 1 is provided with an air flow meter 2, an intake temperature sensor 3, a throttle valve 4, a surge tank 5, and an intake pipe 6 in order from the upstream side. The fuel injection valve 7 is attached to the intake pipe 6 and injects fuel from the intake port into the cylinder. The bypass air passage 8 is provided in parallel with the intake passage portion where the throttle valve 4 is provided, and the ISC
The (idle speed control valve) 9 controls the long road area of the bypass passage 8. The combustion chamber 11 includes a spark plug 12 and is composed of a cylinder head 13, a cylinder block 14, and a piston 15. The fuel injected from the fuel injection valve 7 is mixed in the intake pipe 6 and introduced into the combustion chamber 11 via the intake port opening / closing valve 16. The air-fuel mixture burned in the combustion chamber 11 is discharged to the exhaust pipe 20 via the exhaust port opening / closing valve 19. The oxygen sensor (O ₂ sensor) 21 detects the oxygen concentration in the exhaust gas,
The water temperature sensor 22 is attached to the cylinder block 14 and detects the cooling water temperature. The cylinder discrimination sensor 25 and the rotation angle sensor 26 detect the crank angle from the rotation of the shaft 28 of the distributor 27. The cylinder discrimination sensor and the rotation angle sensor 26 generate a pulse each time the crank angle changes by 720 ° and 30 °, respectively. The throttle sensor 29 detects the opening degree of the throttle valve 4. The electronic control unit 31 receives the detection signal from each of the above sensors and outputs a predetermined control signal to the fuel injection valve 7, ISC 9, and ignition device 32. Ignition device 3
The secondary ignition current of No. 2 is sent to the spark plug 12 via the distributor 27.

(Pumping loss correction) Next, in highlands
Pumping loss correction during idle operation
It Fig. 2 shows filling at low and high altitudes during idle operation.
It is a figure which shows the change of the amount of air. In FIG. 2, in the conventional example
As explained, the atmospheric pressure correction by ISC is usually theoretical.
The correction amount is determined based on the air-fuel ratio (λ = 1), and
The amount of air filling that decreases with ngross is taken into consideration.
Not not. That is, since the air density is low in the highlands,
At the same volume flow rate, mass flow rate at high altitude m₁Is lowland quality
Flow rate m₃It gets smaller. In this state, similar to lowlands
When I / F control of ISC is performed, it is the same as the mass flow rate in lowlands.
The air density is small because it tries to correct the mass flow rate of
The volumetric flow rate is increased by that amount and the idle operation is performed. Shi
However, if the volume flow rate is increased by F / B control,
Since the air pressure in the intake pipe 6 changes to the atmospheric pressure side,
Engine intake to operate at the same idle speed
Negative pressure decreases (engine pumping loss decreases
Low air filling amount (high mass flow rate)
m ₂) Can be operated at the same idling speed as in lowlands. Obedience
Traditionally, ISC F / B control allows mass flow m in lowlands.₃High
High ground mass flow rate m due to ground correction₂Can be set as a result
However, in the conventional high altitude correction, the correction was first made based on the theoretical value.
Since it is corrected, the idling speed will rise above the lowlands.
After that, the rotation speed F / B control by ISC was executed.
Therefore, the allowable margin in F / B control (F / B control
Result of reducing the difference between the upper limit value and the reference value in
Will be invited. Therefore, in this embodiment, the conventional
Instead of the resulting highland correction in such F / B control,
Pump loss correction amount (mass flow rate m₃-M₂) In advance
Function l shown in FIG.₂And then correct the high altitude with theoretical values
Add pumping loss compensation to control idle speed
I decided to do it.

(Countermeasures for Combustion Stability During Idle) Next, the combustion stability during idling at high altitude will be described. When the air filling amount is reduced by the above-mentioned pumping loss correction, the compression pressure in the cylinder is reduced. Generally speaking, the combustion stability during idling deteriorates as the pumping loss decreases (lighter load). Especially in high-power vehicles, the idle stability is low, the valve overlap is set to a large value, and the exhaust gas easily mixes in the cylinder and the potential for idling is low, which may cause rough idle or off idle. Become. In order to improve such idle stability, the present embodiment employs two measures. One measure is to delay the ignition timing at the time of idling as compared with the case of the lowland to increase the air charge amount and reduce the combustion efficiency to achieve the idling stability. Another measure is
By increasing the fuel during idling as compared with the case of lowland, the idling stability is achieved. In either method, the ignition timing retard correction table and the fuel increase rate correction table shown in FIGS. 5 and 6 which will be described later are determined as functions in advance, so that the ignition timing and the fuel set by the load condition at the time of idling are set. The idle speed control is performed by subtracting the correction amount obtained from each correction table to the increase rate.

(Idling Control at High Altitude) Next, a control procedure for improving idle stability while realizing the above-described pumping loss correction will be described. FIG.
3 is a flow chart showing a control procedure at the time of idling of the present embodiment. In FIG. 3, when the process is started, first, in step S2, based on the detection signal of each sensor described in FIG. 1, an electric load such as an air conditioner or an idling state according to an operating state of the power steering device is performed. Determine engine load conditions. In the next step S4, the atmospheric pressure Pa is read based on the detection signal of the air flow meter 2. Then, it progresses to step S6 and reads the engine speed from the ignition signal of the ignition device 32. In step S8, it is determined based on the detection signal from the throttle sensor 29 whether the throttle valve 4 is closed. When the throttle valve 4 is closed in step S8 (step S8
If the determination is YES), the process proceeds to step S10 to determine whether the idle switch is turned on. On the other hand, when the throttle valve 4 is not closed in step S8 (when the determination in step S8 is NO), step S8
Return to 2.

If the idle switch is turned on in step S10 (YES in step S10), the process proceeds to step S12. On the other hand, step S10
Then, when the idle switch is not turned on (when the determination in step S10 is NO), the process returns to step S2. In step S12, in order to determine whether the engine is operating in the idling region, the engine speed detected in step S6 is equal to or less than the idle speed (for example, 1000 rpm), and
In S8 and S10, it is determined whether the throttle valve is closed and the idle switch is turned on. When the engine speed is equal to or lower than the idle speed, the throttle valve is closed, and the idle switch is turned on in step S12 (when the determination in step S12 is YES), the process proceeds to steps S14 and S18. On the other hand, when the engine speed is less than or equal to the idle speed, and the throttle valve is not closed and the idle switch is not turned on in step S12 (when the determination in step S12 is NO), the process returns to step S2.

In step S14, the atmospheric pressure Pa read in step S4 and the ignition timing correction amount are read from the ignition timing correction table shown in FIG. Then, step S1
In step 6, the correction amount read in step S14 is subtracted from the ignition timing corresponding to the engine load condition during idling determined in step S2 to set the final ignition timing for idling at high altitude. That is, it is set based on the following Equation 1.

Formula 1: Final ignition timing = Ignition timing set for each ID load condition-
Correction value read from ignition timing correction table At step S18, the atmospheric pressure Pa read at step S4 and IS from the pumping loss correction table shown in FIG.
The duty correction amount of C is read. Then, step S
At 20, the value obtained by adding the correction value l ₁ set as the theoretical value and the pumping loss correction value l ₂ is the ISC at idle.
By multiplying by the duty value, the final ISC duty value at high altitude is set. That is, it is set based on the following Expression 2.

## EQU2 ## Final ISC duty = ISC duty × (ISC atmospheric pressure correction value l ₁ -pumping loss correction value l ₂ ) Then, when the processing in steps S16 and S20 ends, the process returns to step S2.

As described above, for pumping loss correction, the pump loss correction amount at high altitude is determined as the function l ₂ shown in FIG. 7, and the pumping loss correction is added to the theoretical high altitude correction to set the idle value. With respect to the idle stability, the air-charging amount is increased by delaying the ignition timing at the time of idling from the ignition timing retard correction table shown in FIG. 5 as compared with the case of the lowland.
The combustion efficiency was lowered to control the idle speed. As a result, the idle stability can be improved without deviation of the F / B control reference value by ISC.

(Modification) Next, as a modification of the control procedure described with reference to FIG. 3, a case where the fuel increase rate correction is performed instead of the ignition timing correction will be described. FIG. 4 is a flowchart showing a control procedure at the time of idling as a modified example of the present embodiment. In FIG. 4, the processes of steps S2 to S12 and steps S18 to S12 of FIG.
The following processing will be described.

Now, in step S22, step S4
The atmospheric pressure Pa read in step 3 and the correction amount of the fuel increase rate are read from the fuel increase rate correction table shown in FIG. Then, in step S24, the correction amount read in step S22 is subtracted from the fuel increase rate according to the engine load condition at idling determined in step S2, and the final fuel increase rate for idling in highlands is set. That is, it is set based on the following Expression 3.

Formula 3: Final fuel increase rate = fuel increase rate set for each ID load condition-correction value read from the fuel increase rate correction table Then, when the processing in step S24 ends, the process returns to step S2.

Also in this modification, the idle stability can be improved similarly to the ignition timing correction. The present invention can be applied to the modified or modified embodiment described above without departing from the spirit of the invention. For example, in the present embodiment, the case has been described in which either the ignition timing or the fuel increase rate is corrected for idle stability.
You may control so that one correction may be performed simultaneously.

[0030]

As described above, according to the engine idle speed control system of the present invention, by delaying the ignition timing at the time of idling, the combustion efficiency is lowered and the air charge amount is increased, so that the idling stability is improved. It is possible to improve the sex. By setting the fuel increase rate at the time of idling to be high, the combustion efficiency is lowered, so that the idling stability can be improved.

By controlling the duty of the ISC so as to subtract the volume flow amount of the light load due to pumping loss from the volume flow amount excessively supplied by the atmospheric pressure correction in the conventional ISC, the F / B by the ISC is reduced. It is possible to prevent the reference value for control from deviating.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an engine idle speed control device according to an embodiment of the present invention.

FIG. 2 is a diagram showing changes in the amount of filled air during idle operation in lowlands and highlands.

FIG. 3 is a flowchart showing a control procedure for pumping loss correction and ignition timing correction during idling according to the present embodiment.

FIG. 4 is a flowchart showing a control procedure of pumping loss correction and fuel increase rate correction during idling as a modified example of the embodiment.

5 is a diagram showing an atmospheric pressure table for setting the ignition timing in the flowchart of FIG.

6 is a diagram showing an atmospheric pressure table for setting the fuel increase rate in the flowchart of FIG.

7 is a diagram showing an atmospheric pressure table for setting the ISC duty in the flowcharts of FIGS. 3 and 4. FIG.

[Explanation of symbols]

1 ... intake passage 2 ... air flow meter 3 ... intake air temperature sensor 4 ... Throttle valve 5 ... surge tank 6 ... intake pipe 7 ... fuel injector 8 ... bypass passage 9 ... ISC 21 ... O ₂ sensor 31 ... control device 32 ... Ignition apparatus

Claims (24)

[Claims] 1. An engine idle speed control device for controlling an intake air amount for controlling an engine idling speed to a predetermined speed, wherein the intake air is higher than the low density in the high altitude. Means for determining the value of the intake air amount for obtaining the predetermined number of revolutions based on the air density of F, and F controlled by the value of the intake air amount so that the engine maintains the predetermined number of revolutions. / B control means. 2. The engine idle speed control device according to claim 1, wherein the predetermined speed is set to be the same in the lowland and the highland. 3. The engine idle speed control device according to claim 1, wherein the intake air amount is controlled by an idle speed control valve that bypasses a throttle valve. 4. The means for determining the value of the intake air amount,
2. The engine idle speed control device according to claim 1, wherein a pumping loss reduction amount at high altitude is subtracted from the intake air amount. 5. The engine idle speed control device according to claim 4, wherein the value of the intake air amount is determined based on a mass flow rate. 6. The engine idle speed control device according to claim 5, wherein the mass flow rate in the highlands is set to a value smaller than the mass flow rate in the lowlands. 7. An engine idle speed control device for controlling an intake air amount in order to control an engine idle speed to a predetermined speed, wherein the intake air has a predetermined value in a highland where the intake air is smaller than an air density in a lowland. High altitude correction means for determining a value of a first intake air amount based on a theoretical value to obtain a rotation speed, and second intake air based on the value of the first intake air amount based on an air density of the high altitude And a F / B control means for controlling the engine so that the engine maintains the predetermined rotation speed with reference to the value of the second intake air amount. Engine idle speed control device. 8. The engine idle speed control device according to claim 7, wherein the predetermined speed is set to be the same in the lowland and the highland. 9. The first and second intake air amounts are controlled by an idle speed control valve that bypasses a throttle valve.
The idle speed control device for the engine according to. 10. The engine according to claim 7, wherein the means for determining the value of the second intake air amount subtracts a reduction amount of pumping loss at high altitude from the first intake air amount. Idle speed control device. 11. The engine idle speed control device according to claim 10, wherein the values of the first and second intake air amounts are determined based on a mass flow rate. 12. The engine idle speed control device according to claim 11, wherein the mass flow rate in the highlands is set to a value smaller than the mass flow rate in the lowlands. 13. An engine idle speed control device for controlling an intake air amount for controlling an engine idling speed to a predetermined speed, wherein the intake air is higher than the low density air in the high altitude. Means for determining the value of the intake air amount for obtaining the predetermined number of revolutions based on the air density of, and the air-fuel ratio in the highlands based on the air density of the highlands in a richer direction than the air-fuel ratio in the lowlands. An idle speed control device for an engine, comprising: a control means for controlling. 14. The engine idle speed control device according to claim 13, wherein the predetermined speed is set to be the same in the lowland and the highland. 15. The engine idle speed control device according to claim 13, wherein the intake air amount is controlled by an idle speed control valve that bypasses a throttle valve. 16. The engine idle speed control device according to claim 13, wherein the means for determining the value of the intake air amount subtracts a pumping loss reduction amount at high altitude from the intake air amount. 17. The engine idle speed control device according to claim 16, wherein the value of the intake air amount is determined based on a mass flow rate. 18. The engine idling speed control device according to claim 17, wherein the mass flow rate in the highlands is set to a value smaller than the mass flow rate in the lowlands. 19. An engine idle speed control device for controlling an intake air amount for controlling an engine idling speed to a predetermined speed, wherein the intake air is at a high altitude lower than an air density of a low altitude. Means for determining the value of the intake air amount for obtaining the predetermined number of revolutions based on the air density of, and in the direction of delaying the ignition timing in the highlands based on the air density in the highlands from the ignition timing in the lowlands. An idle speed control device for an engine, comprising: a control means for controlling. 20. The engine idle speed control device according to claim 19, wherein the predetermined speed is set to be the same in the lowland and the highland. 21. The engine idle speed control device according to claim 19, wherein the intake air amount is controlled by an idle speed control valve that bypasses a throttle valve. 22. The engine idle speed control device according to claim 19, wherein the means for determining the value of the intake air amount subtracts the amount of pumping loss reduction at high altitude from the intake air amount. 23. The engine idle speed control device according to claim 22, wherein the value of the intake air amount is determined based on a mass flow rate. 24. The engine idle speed control device according to claim 23, wherein the mass flow rate in the highlands is set to a value smaller than the mass flow rate in the lowlands.