JP4052004B2 - Idle rotational speed control device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention includes an intake air adjusting unit that adjusts an intake air amount during idle operation, and controls the rotational speed of the internal combustion engine to a desired target idle rotational speed by controlling the opening degree of the intake air adjusting unit. The present invention relates to an idle rotation speed control device.
[0002]
[Prior art]
In general, in an in-vehicle internal combustion engine such as an automobile engine, an air-fuel mixture is formed by mixing intake air sucked into a combustion chamber through an intake passage and fuel injected from a fuel injection valve. Driving power is obtained by burning in the combustion chamber. Further, a throttle valve for adjusting the amount of intake air taken into the combustion chamber is provided in the intake passage of such an internal combustion engine, and the output of the internal combustion engine is adjusted through the adjustment of the intake air amount by the throttle valve. Will be adjusted. In recent years, even during idling of the engine, a device for controlling the rotational speed at that time, that is, the idling rotational speed to a target rotational speed through the throttle valve has been put into practical use.
[0003]
By the way, in the internal combustion engine, carbides and oxides such as fuel and lubricating oil, so-called deposits may adhere to or accumulate on the inner wall surface of the intake passage. When deposits adhere or accumulate in this way, the effective cross-sectional area of the intake passage is reduced. Therefore, when the throttle valve opening is the same, if the deposit adheres to or accumulates on the inner wall surface, the amount of air sucked into the combustion chamber is reduced compared to the state without the deposit. In addition, the amount of air-fuel mixture charged in the combustion chamber is reduced. In particular, such a device that controls the idle rotation speed by means of a throttle valve as in the above-mentioned device is also a serious problem, and the amount of intake air decreases during idle operation in which the throttle valve is close to a fully closed state. As a result, the idling speed is likely to be unstable, and engine stalling is likely to occur.
[0004]
Therefore, conventionally, the intake air amount corresponding to the opening degree of the throttle valve that sets the rotation speed of the internal combustion engine to the reference idle rotation speed is learned as a learning value, and the learning value is reflected in the opening degree of the throttle valve. Even when the sticking occurs, the reference idle rotation speed is maintained. Such an idle rotation speed control device is disclosed in, for example, Japanese Patent Laid-Open No. 9-1000073.
[0005]
In the idle speed control device described in the above publication, for example, in order to prevent the internal combustion engine from stalling due to the operation of an air conditioner or the like, control is performed to increase the idle speed from the reference idle speed by a predetermined amount. Is done. At this time, the idle rotation speed control device calculates the control intake air amount to be the target idle rotation speed, and controls the opening of the throttle valve based on the calculated control intake air amount, thereby rotating the rotation speed of the internal combustion engine. Is controlled so as to reach the target idle rotation speed. The control intake air amount is calculated by adding the intake air amount corresponding to the rotation speed change between the target idle rotation speed and the reference idle rotation speed and the learning value. In order to calculate the intake air amount corresponding to the rotational speed change, first, an interpolation value based on a one-dimensional map corresponding to the target rotational speed is calculated. Then, the intake air amount corresponding to the rotational speed change is calculated by subtracting the reference intake air amount for obtaining the reference idle rotational speed in the absence of deposit from the intake air amount calculated by this interpolation.
[0006]
[Problems to be solved by the invention]
However, in the idling engine speed control device, the control intake air quantity for achieving the target idle engine speed is the intake air quantity corresponding to the change in the engine speed between the target idle engine speed and the reference idle engine speed, and the learning value. In addition, it is calculated. Since this learning value is calculated so that the control intake air amount and the required flow rate coincide with each other at the reference idle rotation speed, when the target idle rotation speed and the reference idle rotation speed coincide with each other, the throttle caused by deposit adhesion The change in the flow rate characteristic is taken into the learned value, and there is no problem that the intake air amount is insufficient.
[0007]
However, the intake air amount corresponding to the change in rotational speed between the target idle speed and the reference idle speed in the controlled intake air amount is calculated from a preset map value, and changes in the throttle flow rate characteristics due to deposit adhesion are taken into account. Not done. Therefore, when the target idle rotational speed is different from the reference idle rotational speed, a difference is generated between the intake air amount corresponding to the rotational speed change and the required flow rate. This difference tends to be such that the control intake air amount becomes insufficient with respect to the required flow rate as the learning value increases, that is, as the deposit adhesion amount increases, and as the target idle rotation speed becomes higher than the reference idle rotation speed, The deficiency also increases. As a result, problems such as deterioration of startability of the internal combustion engine and delay in convergence to the target idle rotation speed occur.
[0008]
The present invention has been made in view of the above circumstances, and an object of the present invention is to reduce the difference between the control intake air amount and the required flow rate due to the change in the flow rate characteristic of the intake air adjusting means due to deposit adhesion, An object of the present invention is to provide an idle rotational speed control device for an internal combustion engine capable of performing rotational speed control.
[0009]
[Means for Solving the Problems]
In the following, means for achieving the above object and its effects are described.
According to the first aspect of the present invention, there is provided an intake air adjusting means that is provided in an intake passage of an internal combustion engine and adjusts an intake air amount during idle operation, and an intake air amount that sets the idle rotational speed of the internal combustion engine to a reference idle rotational speed. The amount of control intake air is calculated so that the idling speed of the internal combustion engine becomes a desired target idling speed in consideration of the learning value of the engine, and the opening degree of the intake adjusting means is controlled based on the calculated amount of control intake air In the idle rotation speed control apparatus for an internal combustion engine, the control means includes a control means for controlling the rotation speed of the internal combustion engine to be the target idle rotation speed. A correction value obtained by correcting an intake air amount corresponding to a rotational speed change between a target idle rotational speed and the reference idle rotational speed based on the learned value; and the learned value; In addition to subject matter to be calculated.
[0010]
According to the configuration of claim 1, the control intake air amount includes a correction value obtained by correcting the intake air amount corresponding to the rotation speed change between the target idle rotation speed and the reference idle rotation speed based on the learning value, and the learning value. Calculated by adding The correction value takes into consideration the change in the flow rate characteristic of the intake air adjusting means due to deposit adhesion, and the difference between the control intake air amount and the required flow rate is reduced. As a result, it is possible to solve the problems of deterioration in startability of the internal combustion engine and delay in convergence to the target idle rotation speed.
[0011]
The invention according to claim 2 is the idle rotation speed control device for an internal combustion engine according to claim 1, wherein the control means sets the correction value to a larger value as the learning value is larger. .
[0012]
According to the second aspect of the present invention, the correction value of the intake air amount corresponding to the rotational speed change in the control intake air amount is set to a larger value as the learning value increases, that is, the deposit adhesion amount increases. Therefore, the difference between the required flow rate and the control intake air amount can be suitably reduced, and problems such as deterioration of startability of the internal combustion engine and delay in convergence to the target idle rotation speed can be solved.
[0013]
According to a third aspect of the present invention, in the idle rotational speed control device for an internal combustion engine according to the first or second aspect, the control means is a rotational speed change between the target idle rotational speed and the reference idle rotational speed. The gist is to set the correction value to a larger value as the amount is larger.
[0014]
According to the configuration of the third aspect, the correction value of the intake air amount corresponding to the rotation speed change amount in the control intake air amount is increased as the rotation speed change amount between the target idle rotation speed and the reference idle rotation speed is larger. Set. Therefore, the difference between the required flow rate and the control intake air amount can be suitably reduced, and problems such as deterioration of startability of the internal combustion engine and delay in convergence to the target idle rotation speed can be solved.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment according to an idling engine speed control device for an internal combustion engine of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an automobile gasoline engine system according to the present embodiment.
[0016]
As shown in FIG. 1, a cylinder 13 is formed in a cylinder block 12 constituting the engine 11, and a piston 15 is accommodated in the cylinder 13 so as to be capable of reciprocating. A combustion chamber 16 is defined in the engine 11 by the cylinder 13 and the cylinder head 14 and the upper surface of the piston 15. The engine 11 includes a crankshaft 17 that is an output shaft, and a connecting rod 19 that converts the reciprocating motion of the piston 15 into the rotational motion of the crankshaft 17.
[0017]
A rotational speed sensor 20 that detects the rotational speed of the crankshaft 17 is disposed on the outer wall of the cylinder 13 so as to be positioned in the vicinity of the crankshaft 17. On the other hand, the cylinder head 14 is provided with an intake port 22 and an exhaust port 23 that communicate with the combustion chamber 16. The intake port 22 and the exhaust port 23 are provided with an intake valve 24 and an exhaust valve 25, respectively. An intake manifold 26 is connected to the intake port 22, and an intake passage 26a is formed in the intake manifold 26. The intake manifold 26 is provided with a surge tank 27, and an injector 28 for injecting and supplying fuel to the intake port 22 is provided at the end of the intake manifold 26 on the cylinder head 14 side. Each injector 28 is supplied with fuel at a predetermined pressure from a fuel tank (not shown) by a fuel pump (not shown).
[0018]
Further, the intake manifold 26 is provided with an electronically controlled throttle valve (hereinafter simply referred to as “throttle valve”) 36 that regulates the amount of intake air into the combustion chamber 16 upstream of the surge tank 27. The throttle valve 36 is controlled to be opened and closed by a throttle valve motor 37, and the motor 37 is electrically controlled by an output signal from an electronic control unit (ECU) 40 described later. The opening of the throttle valve 36 is monitored by a throttle sensor 37a, and the monitoring result is taken into the ECU 40.
[0019]
On the other hand, an ignition coil 33 and an igniter 34 are electrically connected to a spark plug 32 provided for each cylinder of the engine 11. The igniter 34 energizes and interrupts the current to the primary coil of the ignition coil 33 based on the ignition signal output from the ECU 40, and the ignition coil 33 is a high voltage induced on the secondary coil side when the primary current is interrupted. As a result, a spark discharge is caused in the spark plug 32. That is, the spark plug 32 performs ignition according to the ignition signal output from the ECU 40 to the igniter 34.
[0020]
The accelerator pedal 38 is provided with an accelerator switch 39 that is turned on when the accelerator pedal 38 is depressed, and an accelerator sensor 39a that outputs a signal corresponding to the depression amount.
[0021]
The ECU 40 includes a central processing unit (CPU) that executes processes related to various controls, a ROM that stores predetermined control programs, a RAM that temporarily stores CPU calculation results, a backup RAM, and the like. The circuit is configured as a logical operation circuit in which a circuit and an external output circuit are connected by a bus.
[0022]
The ECU 40 receives detection values of sensors such as the rotation speed sensor 20, the accelerator switch 39, the accelerator sensor 39a, and the throttle sensor 37a. In addition to the throttle valve motor 37, an injector 28 and an igniter 34 are electrically connected to the ECU 40, respectively. The ECU 40 inputs output signals from the sensors 20, 39a, 37a, the accelerator switch 39, and the like via an external input circuit, and executes various controls such as idle speed control control (hereinafter referred to as "ISC control") of the engine 11. .
[0023]
Here, the ISC control will be described.
This ISC control is performed when the engine 11 is idling, and in order to make the rotational speed during idling coincide with the idling speed according to the driving state of the vehicle, the throttle valve is controlled according to whether the intake air amount is excessive or insufficient. This is done by correcting the opening of 36. In this embodiment, the idle rotation speed of the engine 11 includes the reference idle rotation speed in the normal operation state of the vehicle other than when the engine is started or the air conditioner is operated, and when the engine is started or the air conditioner is operated. The specific idle speed is set. The specific idle rotation speed is set to a value higher than the reference idle rotation speed.
[0024]
Further, the intake air amount corresponding to the opening degree of the throttle valve 36 that sets the idle rotation speed of the engine 11 to the reference idle rotation speed is stored in the RAM or backup RAM of the ECU 40 as an ISC learning value at a predetermined timing. The ISC learning value is the amount of intake air corresponding to the opening of the throttle valve 36 necessary to obtain the reference idle rotation speed regardless of whether deposits are accumulated in the intake passage 26a. The ECU 40 controls the opening degree of the throttle valve 36 based on the stored ISC learning value so as to cope with a change with time in the flow rate characteristic of the throttle valve 36 caused by deposits on the intake passage 26a. Yes.
[0025]
Next, a calculation process of a control intake air amount (hereinafter referred to as ISC flow rate) used for opening control of the throttle valve 36 during ISC control executed by the ECU 40 will be described in detail with reference to the flowchart of FIG. This routine is repeatedly executed at predetermined time intervals.
[0026]
First, in step 110, the target rotational speed change amount from the reference idle rotational speed of the target idle rotational speed is calculated based on the following equation (1).
ednt = entcal-ENTBASE (1)
Edlnt: target rotational speed change (rpm)
entcal: ISC control target idle speed (rpm)
ENTBASE: ISC learning reference idle speed (rpm)
In the next step 120, the ISC flow rate for the target rotational speed change is calculated based on the following equation (2).
[0027]
eqdlnt = (A × eqg + B) × eqdlnt (2)
Eqdlnt: ISC flow rate corresponding to the target rotational speed change (l / sec)
eqg: ISC learning value (l / sec)
A: Constant 1
B: Constant 2
FIG. 3 is a graph showing the results of measuring the relationship between the ISC learning value and the ISC flow rate corresponding to the target rotational speed change. The target idle rotation speed is, for example, two conditions of 1500 rpm and 2250 rpm, and the reference idle rotation speed is set to 1000 rpm, for example.
[0028]
In the conventional example indicated by the chain line in this graph, the ISC flow rate corresponding to the target rotational speed change is calculated from a preset map value, and changes in the throttle flow rate characteristic due to deposit adhesion are not taken into consideration. However, the required flow rate (indicated by symbols ◆ and ▲) with respect to the target rotational speed change has a correlation with the ISC learning value, and the required flow rate increases as the ISC learning value increases. Therefore, when the ISC learning value is around 1.5 (l / sec), the required flow rate and the map value are almost the same, but the larger the ISC learning value is, the higher the target idle rotation speed is than the reference idle rotation speed. The difference between the required flow rate and the map value increases, and the deficiency of the ISC flow rate also increases.
[0029]
The required flow rate (indicated by the symbols ◆ and ▲) can be linearly approximated based on the measurement results of FIG. 3, and the “slope” and “intercept” in the approximate expression are the target rotational speed change (the target idle rotational speed and Therefore, the ISC flow rate corresponding to the target rotational speed change can be calculated by the approximate expression (2). In the measurement result of FIG. 3, when A = 0.0009 and B = 0.00115, the target idle rotation speed is well matched with the required flow rate at both 1500 rpm and 2250 rpm as shown by the solid line in the present invention, and the ISC flow rate. It can be determined that it may be used for the above.
[0030]
In the next step 130, the ISC flow rate corresponding to the target idle rotation speed is calculated based on the following equation (3).
eqnt = eqdlnt + eqg (3)
Eqnt: ISC flow rate corresponding to the target idle rotation speed (l / sec)
As described above in detail, according to the idle rotation speed control device according to this embodiment, the following excellent effects can be obtained.
[0031]
In the present embodiment, the ISC flow rate used for ISC control is an ISC flow rate obtained by correcting a map value corresponding to the target rotational speed change between the target idle rotational speed and the reference idle rotational speed based on the ISC learning value; It is calculated by adding the ISC learning value. The ISC flow rate corresponding to the change in the target rotational speed takes into account the change in the flow rate characteristics of the throttle valve 36 due to deposit adhesion, and the difference between the ISC flow rate and the required flow rate can be reduced. Therefore, problems such as deterioration in startability of the engine 11 and delay in convergence to the target idle rotation speed can be solved.
[0032]
In this embodiment, as the ISC learning value increases, that is, as the deposit adhesion amount increases, the ISC flow rate corresponding to the target rotational speed change is set to a larger value. Therefore, the difference between the required flow rate and the ISC flow rate can be suitably reduced.
[0033]
In the present embodiment, the ISC flow rate corresponding to the target rotational speed change is set to a larger value as the rotational speed change amount between the target idle rotational speed and the reference idle rotational speed is larger. Therefore, the difference between the required flow rate and the ISC flow rate can be suitably reduced.
[0034]
The embodiment can be appropriately changed as follows, for example.
In the above-described embodiment, the engine 11 that performs ISC control is controlled by controlling the opening degree of the throttle valve 36 driven by the throttle valve motor 37. Alternatively, the engine may be embodied in an engine that performs ISC control by controlling the opening of an idle speed control valve (ISCV) provided in a bypass passage that bypasses the throttle valve.
[0035]
In the above-described embodiment, the gasoline engine 11 is embodied. However, the present invention may be embodied in an engine in which fuel is ignited by a spark plug 32, for example, an engine using LPG (liquefied petroleum gas) or LNG (liquefied natural gas) as fuel. Good.
[0036]
Next, other technical ideas that can be grasped from the above embodiments will be described below.
(B) Intake adjustment means provided in the intake passage of the internal combustion engine for adjusting the intake air amount during idle operation, and taking into account the intake air amount learning value that makes the idle rotation speed of the internal combustion engine the reference idle rotation speed Then, a control intake air amount for setting the idle rotation speed of the internal combustion engine to a desired target idle rotation speed is calculated, and is provided in the intake passage of the internal combustion engine based on the calculated control intake air amount. In the method of controlling the idle speed of the internal combustion engine, the rotational speed of the internal combustion engine is controlled to become the target idle speed by controlling the opening of the intake air adjusting means for adjusting the intake air amount. The control intake air amount is an intake air amount corresponding to a change in rotation speed between the target idle rotation speed and the reference idle rotation speed. An idle rotation speed control method for an internal combustion engine, wherein the correction value is corrected based on the equation and the learning value is added.
[0037]
(B) In the idling engine speed control method for an internal combustion engine according to (a), the correction value is set to a larger value as the learning value is larger. Rotation speed control method.
[0038]
(C) In the internal combustion engine idle speed control method described in (a) or (b) above, the correction value increases as the amount of change in the rotation speed between the target idle rotation speed and the reference idle rotation speed increases. An idle rotation speed control method for an internal combustion engine, characterized by being set to a value.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an internal combustion engine to which an idle speed control device of an embodiment is applied.
FIG. 2 is a flowchart illustrating ISC flow rate calculation processing according to the embodiment.
FIG. 3 is an explanatory diagram showing a relationship between an ISC flow rate corresponding to a target rotation speed change and an ISC learning value.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Engine as an internal combustion engine, 26a ... Intake passage, 36 ... Throttle valve as intake adjustment means, 40 ... Electronic control unit (ECU) as control means.

Claims (3)

An intake air adjusting means that is provided in an intake passage of the internal combustion engine and adjusts an intake air amount during idle operation;
A control intake air amount for setting the idle rotation speed of the internal combustion engine to a desired target idle rotation speed is calculated in consideration of a learning value of the intake air amount for setting the idle rotation speed of the internal combustion engine to a reference idle rotation speed, and the calculation Control means for controlling the rotational speed of the internal combustion engine to become the target idle rotational speed by controlling the opening of the intake air adjusting means based on the controlled intake air amount. In the control device,
The control means includes a correction value obtained by correcting the control intake air amount based on the learning value for an intake air amount corresponding to a rotation speed change between the target idle rotation speed and the reference idle rotation speed, and the learning An idle rotation speed control device for an internal combustion engine, characterized in that the calculation is performed by adding the value. The idle rotation speed control device for an internal combustion engine according to claim 1,
The idling speed control device for an internal combustion engine, wherein the control means sets the correction value to a larger value as the learning value is larger. In the idling rotational speed control device for an internal combustion engine according to claim 1 or 2,
The idling speed control device for an internal combustion engine, wherein the control means sets the correction value to a larger value as the amount of change in the speed between the target idle speed and the reference idle speed increases.

Images