JPS6368770A - Internal combustion engine controller - Google Patents

Abstract

PURPOSE:To make an air-fuel ratio controllable to the optimum ignition timing according to the air-fuel ratio of mixture actually burnt, by estimating the air-fuel ratio of mixture to take part in combustion, and compensating fundamental ignition timing to the mixture of a cylinder receiving a combustion stroke according to the estimated air-fuel ratio. CONSTITUTION:Fundamental ignition timing to mixture for an internal combustion engine M1 is set according to a driving state of the internal combustion engine M1, and simultaneously ignition timing control is carried out. In this case, a suction air quantity and a fuel quantity to be fed to each cylinder of the internal combustion engine M1 are estimated by each of estimating devices M2 and M3. And, on the basis of these estimated suction air and fuel quantities, an air-fuel ratio of mixture in the cylinder is estimated by another estimating device M4. And, on the basis of the estimated air-fuel ratio, fundamental ignition timing is compensated by a compensating device M5. With this constitution, ignition to the mixture is carried out by the ignition timing after compensation, whereby the air-fuel ratio of the burnt mixture is made controllable to the optimum ignition timing.

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention [Field of Industrial Application] The present invention relates to an internal combustion engine control device, and more particularly to an internal combustion engine control device that controls the ignition timing of an air-fuel mixture.

[Prior Art] The ignition timing of the air-fuel mixture in an internal combustion engine is one of the biggest factors involved in the progress of combustion, along with the air-fuel ratio of the air-fuel mixture. Electronic ignition timing control devices are used to precisely control ignition timing.

In such an ignition timing control device, the ignition timing that maximizes the output torque without knocking (optimum ignition timing) is determined from a two-dimensional map using the rotation speed and intake pipe pressure (load of the internal combustion engine) as parameters. Further, advance/retard angle correction is performed based on internal combustion engine cooling water temperature, exhaust gas temperature, etc., in order to optimally control the ignition timing.

[Problems to be Solved by the Invention] However, although the optimal ignition timing changes depending on the air-fuel ratio of the air-fuel mixture, ordinary control devices do not incorporate the air-fuel ratio into ignition timing control, and the There has been a problem in that the ignition timing cannot be optimally controlled during a transient period when the air-fuel ratio changes.

Therefore, methods that try to reflect the air-fuel ratio of the air-fuel mixture in ignition timing control (for example, "
``Ignition timing control devices for internal combustion engines'' have been proposed, but since the air-fuel ratio of the air-fuel mixture is determined based on the exhaust composition after combustion, the ignition timing is suitable for the air-fuel ratio of the air-fuel mixture to be ignited. could not be realized.

The present invention has been made to solve these problems, and is to realize ignition timing control that is optimal for the air-fuel ratio of the air-fuel mixture to be combusted.

Structure of the Invention [Means for Solving the Problems] In order to quickly achieve the above object, the present invention has the following structure as a means for solving the problems. That is, as illustrated in FIG. 1, in an internal combustion engine control device that determines the basic ignition timing for the air-fuel mixture of the internal combustion engine M1 according to the operating state of the internal combustion engine M1, and performs ignition timing control, an intake air 4 estimating means M2 for estimating the amount of air M to be supplied to the cylinder; a fuel amount estimating means M3 for estimating the amount of fuel supplied to the cylinder; air-fuel ratio estimating means M4 for estimating the air-fuel ratio of the air-fuel mixture in the
This is the configuration of an internal combustion engine control device characterized by comprising: and ignition timing correction means M5 that corrects the basic ignition timing based on the estimated air-fuel ratio.

Here, the intake air amount estimating means M2 is a means for estimating the amount of intake air finally taken into the cylinder, and for example, at some point in the intake stroke that well reflects the charging efficiency of the internal combustion engine M1. The intake air amount may be estimated using the intake pipe pressure. In addition, various configurations are available, such as a configuration in which the amount of intake air per unit time is detected by an air flow meter such as a hot wire type or vane type, and the amount of intake air until the intake stroke is completed is estimated from this and the rotational speed of the internal combustion engine M1. I can think about the composition.

The fuel amount estimating means M3 is a means for estimating the amount of fuel supplied to the cylinder whose intake air amount has been estimated, and for example, during four cycles (two cycles in a two-stroke engine) before the completion of the intake stroke. This can be easily achieved by collecting the time of the injection pulse output to the fuel injection valve. Strictly speaking, the amount of fuel injected tA does not match the amount of fuel sucked into the cylinder and involved in combustion, so the configuration is designed to accurately estimate the amount of fuel based on a model that simulates the adhesion and evaporation of fuel to the intake port. Good too.

The ignition timing correction means M5 is a means for correcting the basic ignition timing determined according to the operating state of the internal combustion engine M1 based on the air-fuel ratio of the air-fuel mixture estimated by the air-fuel ratio estimating means M4. One possibility is to advance or retard the ignition timing by a predetermined value. It is also conceivable that the amount to be corrected is determined not only from the air-fuel ratio but also from the air-fuel ratio and other parameters (for example, the rotational speed of the internal combustion engine M1, the intake pipe pressure, etc.). Such an ignition timing correction means M5
may be configured as an arithmetic logic operation circuit using a microcomputer or the like together with the air-fuel ratio estimating means M4 etc.
Furthermore, it may be incorporated together with an ignition timing control device and a self-diagnosis device.

[Operation] The intake air ratio estimation means M2 estimates the amount of fuel supplied to the cylinder, and the fuel amount estimation means M3 estimates the amount of fuel supplied to the cylinder, and the air-fuel ratio estimation means M4 uses the estimated intake air ♀ and fuel amount. Based on the air-fuel ratio of the mixture estimated by
The basic ignition timing is corrected by the ignition timing correction means M5.

Therefore, the air-fuel mixture is ignited using the corrected ignition timing.

[Embodiment] In order to further clarify the configuration of the present invention described above, an internal combustion engine opening control device as a preferred embodiment of the present invention will be described next. FIG. 2 is a schematic configuration diagram showing this internal combustion engine control device together with an internal combustion engine.

As shown in the figure, the intake air in this internal combustion engine 1 is
A throttle valve 2 which is sucked in from the air cleaner 1a and is linked to an accelerator pedal (not shown) operated by the driver.
The meteor is controlled by the surge tank 3. It is led to an intake boat 5 via an intake pipe 4. The intake system is provided with a bypass passage 6 that bypasses the throttle valve 2, and in the middle of this bypass passage 6, the amount of air passing through the bypass passage 6 is transferred to a valve body (not shown) driven by a motor. An air control valve 6a is provided.

This air control valve 6a is normally used to control the intake air amount of the internal combustion engine 1 in an idle state to perform so-called idle speed control. Incidentally, as the air control valve 6a, a stepping motor or a near shaft 7/
It is also possible to use a configuration using a rotary id, a rotary 7-noid, or the like. .

On the other hand, 92 fuel injection valves 7 are installed in the intake pipe 4.
Fuel is supplied to the fuel injection valve 7 from a fuel tank (not shown) via a fuel pipe (not shown). Since a pressure regulator (not shown) is provided in the middle of this fuel pipe, the fuel pressure is kept constant. Therefore, when an injection pulse is given to the fuel injection valve 7 to open it, an amount of fuel that is exactly proportional to the width of the injection pulse is injected into the intake port 5. The air-fuel mixture generated at the intake port 5 is introduced into the combustion chamber 9 of the internal combustion engine 1 via the intake valve 8, and is ignited by a spark formed at a spark plug 10 at a predetermined timing. The combustion chamber 9 is partitioned by a piston 11, and exhaust gas generated by combustion of the air-fuel mixture is discharged into the atmosphere via an exhaust valve 12, an exhaust pipe 13, and a catalytic converter 13a having a three-way catalyst.

The internal combustion engine 1 also includes various sensors for detecting its operating state, including an intake pipe pressure sensor 14, an intake air temperature sensor 15, and an intake pipe pressure sensor 14. Throttle sensor 16. Air-fuel ratio sensor 17. A water temperature sensor 1B, a crank angle sensor 19, etc. are provided. The intake pipe pressure sensor 14 is a type of semiconductor pressure sensor 1 and is provided in the surge tank 3, detects the pressure Pm inside the intake pipe, and outputs an analog signal corresponding to the pressure Pm.

The intake temperature sensor ff15 is provided in the air cleaner 1,
An analog signal corresponding to the intake air temperature 1-am is output. The throttle sensor 16 is connected to the rotating shaft of the throttle valve 2, and outputs an analog signal corresponding to the opening degree ψ of the throttle valve 2. This throttle sensor F1'16
has a built-in idle switch 16a, which outputs an ON-OFF signal in response to whether the throttle valve 2 is fully closed or not closed. The air-fuel ratio sensor 17 is attached to the exhaust gas @ 13 and outputs an a log signal according to the residual oxygen humidity λ in the exhaust gas. The crank angle sensor 19 outputs an analog signal according to ThW.
It is installed opposite to the ring gear formed on the shaft of 0, and outputs a pulse signal at every predetermined crank angle. As is well known, the distributor 20 distributes the high voltage generated by the igniter 22 at a predetermined timing to the spark plugs 10 of each cylinder.

Each of the above-mentioned sensors is connected to an electronic control unit (hereinafter referred to as ECU) 25 that controls the fuel injection amount of the internal combustion engine 1.The ECU 25 operates by receiving power from a battery 27. inputs signals from the engine and controls the ignition timing according to predetermined procedures.
Fuel injection control is also performed in which the fuel injection valve 7 is driven to inject fuel according to the amount of intake air determined by the opening degree ψ of the throttle valve 2 and the rotational speed of the internal combustion engine 1.

FIG. 3 is a block diagram showing the configuration of this ECU 25, and as shown in the figure, the ECU 25 includes a well-known CPU 40.
．． ROM41. It is configured as an arithmetic and logic operation circuit centered around the RAM 42 and the like. The CPU 40 etc. are connected to a digital input port 43° and an analog input port 44. Fuel injection valve drive circuit 45, air control valve drive circuit 46. It is interconnected with input/output ports such as an igniter drive circuit 47 via a bus 49.

The digital input port 43 has an idle switch 16.
a. The crank angle sensor 19 is connected, and the CPU 4
0 can read the fully open state of the throttle valve 2 and the rotation angle of the crankshaft, that is, the rotational speed N of the internal combustion engine, through this input port 43. Analog input port 44
is the intake pipe pressure sensor 14. Intake temperature sensor 15. Throttle sensor 16. Air fuel ratio sensor 17. A water temperature sensor 18 is connected and has a function of converting the output signals of each sensor from analog to digital. Therefore, the CPU 40 is
Through this input port 44, the intake pipe pressure Pm of the internal combustion engine 1, the intake temperature Tam, the oxygen concentration λ in the exhaust gas, the cooling water temperature T
hw and the opening degree ψ of the throttle valve 2 can be read sequentially.

The fuel injection valve drive circuit 45 includes a conveyor register and a timer (not shown), and has a function of closing the fuel injection valve 7 when the time measured by the timer reaches the time written in the conveyor register.

Therefore, if the CPU 40 outputs a control signal to close the fuel injection valve 7 and writes the valve closing time in the conveyor register, the fuel injection valve drive circuit 45 can close the fuel injection valve 7 at that time. Therefore, the CPtJ40 can perform fuel injection control without worrying about the timing of valve closing.

On the other hand, the air control valve drive circuit 46 has a function of rotating the motor of the air control valve 6a forward and backward by a predetermined amount.

Therefore, the CPtJ 40 opens and closes the air control valve 6a by the necessary amount via this circuit 46, and can increase or decrease the intake air amount of the internal combustion engine 1 not only when idling but also when driving. The igniter drive circuit 47 is connected to the battery 27
1 of the step-up transformer (not shown) of the igniter 22.
It has a switching element (not shown) that connects and connects the secondary coil to turn on and off the primary side circuit of the igniter 220 at high speed. Therefore, by turning on and off the switching elements of this circuit 47, the CPU 40 can generate a high voltage in the secondary side circuit of the igniter 22 at a desired timing. The ignition timing θ of the internal combustion engine 1 can be freely advanced or retarded by the sparks formed in the spark plugs 10 of each cylinder by this high voltage.

In the internal combustion engine control device having the above configuration, the ECU
The control carried out by 25 will be explained next.

The ECU 25 executes an ignition timing correction routine shown in FIG. 4 separately from well-known ignition timing control (not shown) that determines the basic ignition timing θa. This routine is executed for each cylinder at every predetermined crank angle, and first performs a process of estimating the total amount of fuel τ taken into the cylinder (step 1).
00). The total fuel ωτ is estimated by calculating the total amount of fuel injected from the completion of the previous intake stroke until now. Specifically, the effective injection pulse width t of the fuel injection pulse is estimated. Since and the fuel injection amount are proportional to each other, as shown in FIG.
This is done by adding (in Σ) x, etc. The estimated fuel injection amount τ is stored in a predetermined area within the RAM 42. Next, in order to estimate the amount of air taken into the cylinder, a process is performed to read the intake pipe pressure Pm from the intake pipe pressure sensor 14 via the analog input port 44 (step 120). Since the filling efficiency of the air-fuel mixture in each cylinder of the internal combustion engine 1 is almost controlled by the intake pipe pressure pm, the total intake air amount can be controlled by the intake pipe pressure pm at a predetermined timing in the intake stroke before the intake stroke is completed. It can be estimated. If a sensor is installed to measure the intake air amount ff1Ga per unit time, the value 1/N (N
(rotational speed), and the total intake air amount may be estimated by the value Ga/N.

In the subsequent step 120, the intake pipe pressure as the estimated value of the total intake air amount read in step 110 is divided by the total fuel mτ estimated in step 100 (Pm/τ).
, the air-fuel ratio estimated value Δ/Fobs is calculated.

This air-fuel ratio estimated value A/Fobs is a value estimated before the intake stroke is completed, as the air-fuel ratio of the air-fuel mixture involved in combustion after the intake stroke is completed. Therefore, based on this air-fuel ratio estimated value A/Fobs, the air-fuel ratio of the air-fuel mixture can be known without detecting the oxygen concentration λ in the exhaust gas after combustion. Therefore, in step 130, this air-fuel ratio estimated value A
/ The value of F obs is used to correct the basic ignition timing Oa. That is, as shown in Fig. 6, there is a certain correlation between the air-fuel ratio and the ignition timing that can extract the maximum torque without causing knocking. Then, in an ignition timing control routine (not shown), a predetermined basic ignition timing θa is corrected from the internal combustion engine rotation speed N and the intake pipe pressure pm.

The ignition of the air-fuel mixture is performed by the igniter drive circuit 4 according to an ignition control routine (not shown) according to the corrected ignition timing.
This is done by driving the igniter 22 via the igniter 7. After completing the process in step 130, the process returns to rNEXTJ and this routine ends.

As explained above, the internal combustion engine control device of this embodiment is
The air-fuel ratio of the air-fuel mixture, which is directly involved in combustion, is estimated before combustion, and the ignition timing of the air-fuel mixture is optimally corrected according to the air-fuel ratio. Therefore, even during so-called transient times when the air-fuel ratio changes significantly due to asynchronous fuel injection, etc. performed when the accelerator is depressed, the ignition timing can be optimally controlled, without causing knocking in the internal combustion engine 1. Output torque can be improved. As a result, it is not necessary to make the knocking resistance of the internal combustion engine 1 excessively high, and it is possible to reduce the weight of the internal combustion engine 1 and improve its durability.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments in any way, and it goes without saying that it can be implemented in various forms without departing from the gist of the present invention.

Effects of the Invention As detailed above, the internal combustion engine control device of the present invention estimates the air-fuel ratio of the air-fuel mixture involved in combustion, and adjusts the air-fuel ratio to the air-fuel mixture of the cylinder undergoing the combustion stroke according to the estimated air-fuel ratio. The timing of ignition (basic ignition timing) can be corrected. Therefore, the optimal ignition timing can be realized according to the air-fuel ratio of the air-fuel mixture actually combusted, and the extremely excellent effect of improving the output torque without causing knocking is achieved. These effects are
This is particularly noticeable when the internal combustion engine is in a transient state, and can contribute to reducing the weight and improving the durability of the internal combustion engine.

[Brief explanation of the drawing]

FIG. 1 is a block diagram illustrating the basic configuration of the present invention, FIG. 2 is a schematic configuration diagram showing an internal combustion engine control device as an embodiment of the present invention together with the configuration of the internal combustion engine, and FIG. 3 is an electronic control device as well. (ECU), FIG. 4 is a flowchart showing the ignition timing correction routine executed by the electronic control unit 25, FIG. 5 is an explanatory diagram showing how to calculate the total fuel injection amount τ, and FIG. It is a graph showing the relationship between air-fuel ratio and optimal ignition timing. 1... Internal combustion engine 2... Throttle valve 6a... Air control valve 7... Fuel injection valve 10... Spark plug 14... Intake pipe pressure sensor 15... Intake temperature sensor 16... - Throttle sensor 16a... Idle switch 17... Air-fuel ratio sensor 18... Water temperature sensor 19... Crank angle sensor 22... Igniter

Claims (1)

[Claims] 1. In an internal combustion engine control device that determines the basic ignition timing for the air-fuel mixture of the internal combustion engine according to the operating state of the engine and performs ignition timing control, the amount of air taken into a cylinder is estimated. an intake air amount estimating means for estimating the amount of fuel supplied to the cylinder; and an air-fuel ratio of the air-fuel mixture in the cylinder based on the estimated intake air amount and the fuel amount. An internal combustion engine control device comprising: an air-fuel ratio estimating means for estimating the air-fuel ratio; and an ignition timing correcting means for correcting the basic ignition timing based on the estimated air-fuel ratio.