JPH1054283A - Idling rotational speed controller for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a problem of conflicting between overshoot and response delay which is generated in a short or long control cycle by changing cycle of feedback control according to the large or small rotational speed deviation of actual rotational speed from targeted idling rotational speed. SOLUTION: When an ECU 9 built in with a microcomputer detects the idling condition of an engine 1 by an output from an idle sensor 8, the ECU 9 calculates the rotational speed deviation of the output from a rotational speed sensor 7 from targeted idling rotational speed preset at the ECU 9. If the rotational speed deviation is less than a first determined value, feedback control is not conducted. If the rotational speed is the first determined value or higher, feedback is conducted by a first cycle. If the rotational speed deviation is a second determined value or higher during the feedback control, feedback control is conducted by a second cycle shorter than the first cycle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an idle speed control device for performing feedback control so that an actual idle speed of an engine converges to a target idle speed.

[0002]

2. Description of the Related Art For example, in Japanese Patent Publication No. 2-14979, a feedback control value is set in accordance with a deviation between an actual engine speed and a target idle speed, and the suction supplied to the engine according to the control value. An idle speed control device that performs feedback control so as to converge an idle engine speed to a target idle speed by controlling an air amount is disclosed.

[0003]

However, in the above-described control device, feedback control is performed for each control cycle at a predetermined timing. For example, if the control cycle is set to be short, a predetermined target idle speed is not satisfied. The actual engine speed may overshoot, or conversely, if the control cycle is set longer, the response until the actual engine speed reaches the target idle speed will be delayed,
As a result, there is a problem in that the drivability is reduced, and the engine is stalled. In other words,
In the above-described control device, only the feedback control value is switched in accordance with the rotational speed deviation at a constant control cycle T,
The feedback control is started in the case where the load of the engine with a small load of electric consumption shown in FIG. 6 is small and the case of the heavy load of the engine with a large load of electric consumption shown in FIG. 7. The timings are both at time A, and both have the same rotational speed deviation as ΔNe, so that the feedback control value is set to be the same for both. Then, as shown in FIG. 7, when the load is large, the next update timing is after a certain control cycle T,
During a control cycle T from time A, engine stall may occur.

In order to solve the above-mentioned problems, the present invention changes the period of the feedback control in accordance with the magnitude of the rotational speed deviation between the actual engine rotational speed and the target idle rotational speed. It is an object of the present invention to provide an engine idle speed control device capable of solving a conflict between an overshoot and a response delay that occur in a long and short time, improving a driver billidy, and preventing an engine stall. .

[0005]

According to a first aspect of the present invention, when the engine is in an idle state, the intake air amount of the engine is controlled by a comparison output of a preset target idle speed and an actual engine speed. An idle speed control device that performs feedback control for each control cycle at a predetermined timing so that the actual engine speed is equal to the target idle speed is provided by an idle speed control device that calculates the rotation speed between the target idle speed and the actual engine speed. First comparing means for comparing the deviation with a preset first determination value; and
A second comparing means for comparing a preset second judgment value larger than the judgment value with a predetermined output based on a judgment output indicating that a rotational speed deviation from the first comparing means is larger than the first judgment value; The feedback control is executed every one cycle T1, and during the feedback control, a predetermined output shorter than the first cycle T1 is obtained by a determination output from the second comparing means that the rotational speed deviation is larger than the second determination value. A period switching means for immediately starting the feedback control every two periods T2. According to the first aspect, when the engine is idling, the rotational speed deviation ΔNe
Is smaller than the first determination ΔNe value, the feedback control is not performed. If the rotation speed deviation ΔNe is equal to or more than the first determination value ΔNe1 (ΔNe ≧ ΔNe1), the feedback control is performed in a predetermined first cycle T1. During the feedback control, when the rotation speed deviation ΔNe becomes equal to or more than the second determination value ΔNe2 (ΔNe ≧ ΔNe2), the feedback control is started in the second cycle T2 shorter than the first cycle T1, thereby increasing the engine load. , The rotation speed deviation Δ
When Ne becomes equal to or greater than the second determination value ΔNe2, the cycle of the feedback control is switched from the first cycle T1 to the second cycle T2, the next update timing can be shortened, and the driver billidy can be improved, and the engine can be improved. Stalls can be prevented.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG.
The description will be made based on .about.5. FIG. 1 is a block diagram showing an internal combustion engine control device including idle speed control (ISC control). In FIG. 1, reference numeral 1 denotes an internal combustion engine composed of a 4-cycle engine, 2 denotes an intake pipe for introducing air into the internal combustion engine 1, Is a throttle valve that controls the amount of air introduced into the intake pipe 2 in conjunction with an accelerator pedal (not shown) operated by an occupant. 4 is a throttle valve when the throttle valve 3 is fully closed, that is, when the internal combustion engine 1 is idling. An ISC valve that adjusts the amount of bypass air to the intake pipe 2 by an output from an electronic control unit (hereinafter, referred to as an ECU) 9 including a microcomputer described later detects the amount of intake air of the internal combustion engine 1 and converts the value. An air flow sensor 6 outputs an electric signal to the ECU 9, and an intake pipe 2 located between the internal combustion engine 1 and the throttle valve 3 based on an output from the ECU 9. An injector 7 for injecting fuel therein, a rotation speed sensor 7 for detecting a rotation speed of the internal combustion engine 1 and outputting an electric signal converted to the ECU 9, and a rotation speed sensor 8 for a fully closed state of the throttle valve 3, that is, an idle state of the internal combustion engine 1. The idle sensor outputs the detected and converted electric signal to the ECU 9.

[0007] The ECU 9 has a fuel control unit and an idle speed control unit. The fuel control unit controls the amount of fuel injected into the injector 6 based on the amount of intake air from the air flow sensor 5. The idle speed control unit outputs a control signal to the ISC valve 4 based on various types of load information 10 such as the idle sensor 8 and other water temperature sensors (not shown), and adjusts the amount of bypass air to the intake pipe 2.

The idle speed control section includes a first comparing means 9a, a second comparing means 9b, and a cycle switching means 9c. The first comparing means 9a determines the rotational speed deviation Δ between the actual engine rotational speed Ne of the internal combustion engine 1 detected by the rotational speed sensor 7 and a preset target idle rotational speed Neobj.
Ne (ΔNe = | Neobj−Ne |) is compared with a preset first determination value ΔNe1. Second comparing means 9b
Is a second determination value ΔNe in which the rotational speed deviation ΔNe is set in advance.
Cycle switching means 9c for comparing with the first comparison means 9a
The feedback control cycle is set to a predetermined first cycle T1 according to the comparison result of the second comparison means 9b.
And a predetermined shorter second period T2, and outputs an idle speed control signal to the ISC valve 4.

The first determination value ΔNe is data set to prevent excessive feedback control, and is usually 30
５０50 rpm, and the dead zone (dead
This is data that is defined to start feedback control when the rotational speed deviation ΔNe is equal to or greater than ΔNe1 (ΔNe ≧ ΔNe1). For example, the data may be changed from a deceleration state to an idle state. This data does not depend on the operating state of the engine.

The second determination value .DELTA.Ne2 is data set for performing the feedback control little by little in order to prevent the occurrence of engine stall when the load on the internal combustion engine 1 is large during the feedback control.

Reference numeral 11 denotes an air filter for filtering air sucked into the suction pipe 2.

Next, according to the flowchart of FIG.
The idle speed control operation in U9 will be described.

The process shown in FIG. 2 is performed by the main routine of the microcomputer in the ECU 9. Step 20
In step 1, a rotational speed deviation ΔNe between the actual engine rotational speed Ne of the internal combustion engine 1 and the target idle rotational speed Neobj is calculated. In step 202, it is determined whether or not it is time to determine the switching of the feedback control cycle based on the value of the second timer. When the second timer is # 0, it is determined that it is the switching determination timing, and the routine proceeds to step 203. Step 203
Then, it is determined whether or not the cycle of the feedback control is switched. That is, when ΔNe is smaller than the second determination value ΔNe2, the cycle of the feedback control is not switched.
Proceed to step 206. If ΔNe is equal to or greater than the second determination value ΔNe2, the process proceeds to step 204 to switch the cycle of the feedback control. In step 204, the first
The timer is reset to 0 and the routine proceeds to step 205. In step 205, the second timer is preset to a predetermined second period T2 shorter than the predetermined first period T1 of the feedback control.

Here, the first timer indicates the first period T1 of the feedback control. The second timer indicates the feedback control cycle switching determination timing and also indicates the second cycle T2 of the feedback control when ΔNe is equal to or greater than the second determination value ΔNe2.

Since both the first timer and the second timer are decremented at predetermined time intervals as shown in the flow chart of FIG. 3, when the timer value is 0, it means that the predetermined time has elapsed.

In step 206, it is determined whether or not it is time to start the feedback control based on the value of the first timer. When the first timer is # 0, it is determined that it is not time to start the feedback control, and the routine proceeds to step 210, where the present processing is terminated. When the first timer = 0, it is determined that it is the feedback control timing, and the process proceeds to step 207. In step 207, it is determined whether the feedback control is actually performed. That is, if ΔNe calculated above is less than the first determination value ΔNe1, it is determined that the feedback control condition is not satisfied, and the routine proceeds to step 210, where the present processing is terminated. ΔNe first determination value ΔN
If e1 or more, it is determined that the feedback control condition is satisfied, and the routine proceeds to step 208. In step 208, the value of the first timer is preset to the first period T1, and the process proceeds to step 209. In step 209, after performing the feedback control, the process proceeds to step 210, and the present process ends.

FIG. 4 is a timing chart showing an actual feedback control operation in the flowchart processing described above. Fig. a shows the actual engine speed Ne of the internal combustion engine 1, and Neob in the figure is a target idle speed. The figure b shows the rotational speed deviation ΔN between Ne and Neobj.
In the figure, ΔNe1 is a first determination value, and ΔNe2 is a second determination value. Fig. c shows the operation of the second timer during the idle speed control in the microcomputer in the ECU 9, and Fig. d shows the operation of the first timer during the idle speed control in the microcomputer in the ECU 9. I have. 5E shows a period of the feedback control during the idle speed control in the microcomputer in the ECU 9, where T1 is the first period and T2 is the second period.
It is a cycle. FIG. 7f shows the timing at which the feedback control is started during the idle speed control in the microcomputer in the ECU 9.

In the idle state, when the rotation speed Ne of the internal combustion engine 1 overshoots the target idle rotation speed Neobj, a rotation speed deviation ΔNe occurs as shown in FIG. If ΔNe <ΔNe1, feedback control is not performed, and both the first timer and the second timer remain at 0. Next, if the condition of ΔNe ≧ ΔNe1 is satisfied as at times t1 and t8, the feedback control is performed immediately and the first timer is set to the first timer.
Preset to cycle T1. Therefore, when the transition is performed under the condition of ΔNe1 ≦ ΔNe <ΔNe2 as at time t9, the feedback control is performed at the time when the first timer = 0, that is, at the first cycle T1. Next, as at time t2, ΔN
When the condition of e ≧ ΔNe2 is satisfied, the second timer = 0
If so, the first timer is reset to 0, so feedback control is performed at that time. Thereafter, the first timer is preset with the first period T1, and the second timer is preset with the second period T1.
The cycle T2 is preset.

The first cycle T1 and the second cycle T2 of the feedback control satisfy the relationship of T1 ≧ T2, but when the second timer = 0, the first timer is immediately cleared. Therefore, the cycle of the feedback control is determined by the operation cycle of the first timer. However, if the condition of ΔNe ≧ ΔNe2 is satisfied, the operation cycle of the first timer apparently matches the operation cycle of the second timer, and The feedback control can be started in the cycle T2.

In short, according to this embodiment, when the rotational speed deviation ΔNe is less than the first determination value ΔNe1 (ΔNe <ΔNe1) when the internal combustion engine 1 is in an idle state,
Without the feedback control, the rotation speed deviation ΔNe
If it is equal to or greater than the determination value ΔNe1 (ΔNe ≧ ΔNe1), feedback is performed in a predetermined first cycle T1, and during this feedback control, ΔNe becomes the second determination value ΔNe.
When 2 or more (ΔNe ≧ ΔNe2), the feedback control is started in a predetermined second cycle T2 shorter than the first cycle T1.

Therefore, as shown in FIG. 5, even when the load of the engine is large when a load with a large electric consumption is applied,
When the rotation speed deviation ΔNe becomes equal to or greater than ΔNe2, the cycle of the feedback control is switched from the first cycle T1 to the second cycle T2, and the next update timing is shortened, so that engine stall can be prevented.

For example, when a headlamp or the like is turned on, the charge amount of a battery mounted on a vehicle driven by the internal combustion engine 1 decreases, and an alternator (generator) mounted on the vehicle starts generating power. 1 is loaded, and the rotation speed of the internal combustion engine 1 decreases. Therefore, the rotation speed deviation ΔNe
Is greater than or equal to the first determination value ΔNe1 (ΔNe ≧ ΔNe1), feedback control is started, and control is performed so that the actual engine speed Ne matches the target idle speed Neobj. In this case, when the load of the internal combustion engine 1 is small, feedback control is performed in the first cycle T1 to control the internal combustion engine 1 to a desired rotation speed. The first cycle T1 roughly adopts a time of about 1 second in order to prevent the divergence of the control system. When a load that consumes a large amount of power is applied, the decrease in the rotation speed of the internal combustion engine 1 increases. Therefore, in this embodiment, the rotation speed deviation ΔNe is equal to or larger than the second determination value ΔNe2 (ΔNe ≧ ΔNe2).
Becomes the first period T
By making the second cycle T2 shorter than 1, it is possible to prevent engine stall from occurring.

[0023]

According to the first aspect of the present invention, when the engine is idling, the control cycle is switched between long and short according to the rotational speed deviation between the actual engine rotational speed and the target idle rotational speed. The problem of overshoot and delay in response can be solved, driver billidy can be improved, and engine stall can be prevented.

[Brief description of the drawings]

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

FIG. 2 is a flowchart of idle speed control according to the embodiment.

FIG. 3 is a flowchart of a timer according to the embodiment.

FIG. 4 is a timing chart of the embodiment.

FIG. 5 is an operation explanatory view of the embodiment.

FIG. 6 is an explanatory diagram of an operation when a conventional load is small.

FIG. 7 is an explanatory diagram of an operation when a conventional load is large.

[Explanation of symbols]

1 internal combustion engine, 2 intake pipe, 3 throttle valve, 4
ISC valve, 5 air flow sensor, 6 injector, 7 speed sensor, 8 idle sensor, 9
Electronic control unit (ECU), 9a first comparing means, 9
b Second comparing means, 9c Period switching means, 10 Load information from various sensors.

Claims (1)

[Claims] When the engine is in an idle state, an intake air amount of the engine is controlled by a comparison output between a preset target idle speed and an actual engine speed,
In an idle speed control device that performs feedback control for each control cycle at a predetermined timing so that the actual engine speed becomes the target idle speed, a rotation speed deviation between the target idle speed and the actual engine speed is provided. First comparing means for comparing the rotational speed deviation with a preset second determining value larger than the first determining value, and first comparing means for comparing the rotational speed deviation with a preset second determining value larger than the first determining value. The first cycle T1 is determined by a judgment output from the first comparing means indicating that the rotational speed deviation is larger than the first judgment value.
Feedback control is executed every time, and during the feedback control, the first cycle T1 is determined by a judgment output indicating that the rotational speed deviation from the second comparing means is larger than the second judgment value.
A period switching means for immediately starting the feedback control at every predetermined second period T2 shorter than the predetermined period T2.