JPS61232342A - Engine controller - Google Patents

Abstract

PURPOSE:To check any variation in a suction air charging quantity as well as to control a torque variation, by making throttle valve opening fully open in time of selection to rich driving, in case of a device which selects lean driving to the rich driving and vice versa according to a degree of engine load. CONSTITUTION:A pedal operated variable in an accelerator pedal 5 is detected by an accelerator opening sensor 16, and in the case where opening regulation for a throttle valve 6 is carried out with an actuator 7 according to the output, the actuator 7 is controlled so as to make opening of the throttle valve 6 fully open at the time of judging the rich driving that accelerator opening becomes more than the specified value. And, at this time, a fuel injection valve 12 is controlled in order to alter an air-fuel ratio to the rich side in response to the accelerator opening. At this juncture, the air-fuel ratio is set to a value corresponding to lean driving in case an accelerator operated variable alpha is below a second specified variable alpha2, and in case of a first specified variable alpha1, to a theoretical air-fuel ratio as well as in case of the second specified variable alpha3 (alpha3>alpha1>alpha2), to a value corresponding to rich driving, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an engine control device, and in particular, to switching between lean operation with a large air-fuel ratio and rich operation with a small air-fuel ratio in accordance with the accelerator operation amount indicating the required engine output. The present invention relates to an engine control device that performs the following operations.

(Prior Art) In order to save fuel as much as possible, some engines are required to perform lean operation with a high air-fuel ratio when the engine load is small, while at the same time requiring output.

Some engines perform rich operation with a small air-fuel ratio when the engine load is large. In general, intake negative pressure or intake air amount is used as a parameter representing the load for determining such switching between lean and rich.

Conventionally, as a technique for controlling the air-fuel ratio of the engine to a predetermined air-fuel ratio with respect to the accelerator operation amount indicating the required engine output, as shown in Japanese Patent Application Laid-Open No. 57-65835, the throttle control is controlled according to the accelerator operation amount. It is known that the valve opening degree (that is, the amount of intake air) is electrically controlled.

(Problems to be Solved by the Invention) However, in the above conventional system, the change in engine output is large when transitioning from lean operation to rich operation, causing problems in obtaining stable drivability. Ta.

To explain this point in detail, when transitioning to rich operation, there is an increase in output due to an increase in charging amount (increase in intake air amount) due to an increase in engine load, and an increase in output due to the transition from lean to rich air-fuel ratio. The two output-improvement factors overlapped, resulting in large overall output fluctuations.

In addition, recently, the increase in output due to the increase in the amount of fuel has tended to be kept relatively small due to the expansion of the lean operating range, that is, lean operation is performed until the engine load becomes considerably large. However, it is still not completely satisfactory from the viewpoint of preventing output fluctuations.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an engine control device that switches between lean operation and rich operation depending on the engine load, and is capable of reducing output fluctuations during this switching. purpose.

(Means for Solving the Problem 1 Effect) In order to achieve the above-mentioned object, the present invention basically aims at preventing a change in the filling amount, which is a factor of output fluctuation, from occurring when switching to rich operation. This is what I did. In other words, even if the throttle valve opening is changed from the conventional throttle valve opening when switching to rich operation to full open, the change in the throttle valve opening during this period is large, but the change in intake air amount is small. be. By the way, this was done by paying attention to the fact that if the throttle valve is fully open when the opening degree is 80 degrees, the filling amount is already around 90% when the opening degree is 20 degrees.

From the above-mentioned viewpoint, one aspect of the present invention is lean.

The rich switching is performed according to the accelerator operation amount, and the throttle valve opening is electrically controlled according to the accelerator operation amount, so that the throttle valve is fully opened when switching to rich operation. That's how it is. Specifically, the present invention includes: an accelerator detection means for detecting an accelerator operation amount; and a throttle valve control means that receives the output of the accelerator operation amount and controls the throttle valve to be fully open at least when the accelerator operation amount is equal to or greater than a predetermined amount. , receiving the output of a fuel supply means for supplying fuel to the engine and the accelerator detection means, and controlling the fuel supply means;
This configuration includes air-fuel ratio control means for changing the air-fuel ratio in response to the accelerator operation amount when the accelerator operation amount exceeds the predetermined amount.

With this configuration, when switching to rich operation, the throttle valve opening is already fully open, so there is no change in the charging amount, and the air-fuel ratio changes depending on the accelerator operation amount, so there is no change in output. It becomes continuous and there is no torque fluctuation.

(Example) Hereinafter, an example of the present invention will be described based on the drawings from FIG. 2 onwards.

FIG. 2 shows the overall configuration of an engine control device according to an embodiment of the present invention, where l is, for example, a four-cylinder engine, and 2 is one end that opens to the atmosphere via an air cleaner 3 and the other end that opens to the engine l. An intake passage 4 supplies intake air to the engine 1, and an exhaust passage 4 has one end open to the engine 1 and the other end opened to the atmosphere to discharge exhaust gas from the engine 1.
is an accelerator pedal that is depressed in response to the engine output request, and 6 is a throttle valve that is disposed in the intake passage 2 and controls the amount of intake passage, and the throttle valve 6 is mechanically linked to the accelerator pedal 5. There is no relationship, and as will be described later, it is electrically controlled by the amount of depression of the accelerator pedal 5, that is, the amount of accelerator operation. Reference numeral 7 denotes a throttle actuator comprising a step motor or the like that opens and closes the throttle valve 6.

Reference numeral 8 denotes a catalyst device which is interposed in the exhaust passage 4 and purifies exhaust gas.

On the other hand, reference numeral 12 denotes a fuel injection valve disposed downstream of the throttle valve 6 in the intake passage 2 to inject and supply fuel. The fuel tank 16 is connected to the fuel tank 16 through the fuel tank 16, and the fuel is supplied from the fuel tank 16, and the surplus fuel is returned to the fuel tank 16 via the fuel pressure regulator 17 or the turn passage 18. Therefore, fuel at a predetermined pressure is supplied to the fuel injection valve 12.

In addition, 19 is an accelerator pedal position sensor as an accelerator detection means for detecting the amount of depression of the accelerator pedal 5, that is, the accelerator operation amount α, and 20 is disposed upstream of the throttle valve 6 in the intake passage 2 to detect the intake air amount QaR. 22 is a throttle position sensor that detects the opening degree of the throttle valve 6; 23 is a water temperature sensor that detects the engine cooling water temperature TIII; 24 is a water temperature sensor that is disposed upstream of the catalyst device 8 in the exhaust passage 4 and is arranged in the exhaust gas. An air-fuel ratio sensor (lean sensor) that detects an air-fuel ratio λ of
These detection signals 19 to 24 are input to a control unit 25 consisting of a digital computer or the like, and the control unit 25 controls the throttle actuator 7 and the fuel injection valve 12.

Further, a hiveniter 26 is connected to the control unit 25, and a signal indicating the number of ignitions, that is, the engine rotation speed Ne is inputted, and an ignition timing signal set at a predetermined timing is outputted to the igniter 26. It looks like this.

Further, a distributor 27 and a battery 28 are connected as inputs to the control unit 25, and receive signals of ignition timing and battery voltage VB, respectively. Of course, the ignition signal from the igniter 26 is output as a secondary current supply to the spark plug 33 via the destroyer 27, and the spark plug 33 is ignited, and the igniter 26 and the destroyer 26 perform ignition control. constitutes a means.

In the embodiment, the control unit 25 described above controls the amount of fuel to the engine 1 according to the accelerator operation amount α in parallel with controlling the throttle valve 6 to the target opening according to the accelerator operation amount α. It has become something to do. The operation of this control unit 25 will be described below. For convenience of explanation, the throttle control and fuel control will be explained in general, and then the air-fuel ratio control part, which is a feature of the present invention, will be explained. Note that FIG. 3 shows the case of a four-cylinder engine.

Throttle control In FIG. 3, first, the throttle valve opening control system will be described. MA l is the target value Qa of air supplied to the engine l so that the air-fuel ratio is set in advance for the accelerator operation amount α. is set, and receives the output from the accelerator pedal position sensor 19,
It constitutes a target air amount setting means 29 that sets a target value air 1Qa1 to be supplied to the engine l according to the accelerator operation amount α.

MA2 is a second map in which the minimum air amount Qam is set to provide the air-fuel ratio necessary for idle up with respect to the engine coolant temperature Tw, and MA2 receives the output from the water temperature sensor 23 and determines the engine coolant temperature. The minimum air amount Qam for water temperature correction is set according to TIN. 30 is the first map MA1 (target air amount setting means 29)
Then, the maximum value Qa2 of the target air amount Qa1 obtained from the first map MA 1 and the minimum air amount Qam for water temperature correction obtained from the second map MA 2 is received. It is a maximum value selection circuit to select,
When the target air amount Qa1 is lower than the minimum air amount Qam for water temperature correction, the minimum air amount Qam for water temperature correction is selected to increase the idle, thereby ensuring good engine operability.

MA3 is a third map in which a maximum air amount Qam determined by the engine speed Ne is set with respect to the engine speed Ne, and the maximum air amount Qam is set according to the engine speed Ne. 31 receives each output of the maximum value selection circuit 30 and the third map MA3;
The minimum value selection circuit selects the minimum value Qa3 of the maximum air amount Qaz obtained by the maximum value selection circuit 30 and the maximum air amount QaM obtained from the third map MA3, and the target air amount Qax is When the maximum air amount QaM determined by the engine speed Ne is exceeded, it is meaningless to set the target value to be more than the amount of air that can be taken in when the throttle valve 6 is fully open. I am trying to limit the maximum value.

As described above, the target air amount Qa3 is determined for the accelerator operation amount α, taking into account the correction for the engine coolant temperature TW and the correction for the maximum air amount at full throttle valve opening determined by the engine speed Ne.

Furthermore, 32 is a divider that receives the output from the minimum selection circuit 31 and divides the target air amount Qa3 by a value (N e X 2) that is twice the engine speed Ne. The intake air amount Ac1 per cylinder is calculated.

MA4 is the target value intake air amount Ac for the engine speed Ne
1. This map MA4 receives the output from the divider 32 and sets the throttle valve opening O1 that should be the target value intake air amount Acl. This constitutes the target throttle valve opening determining means 33.

Further, 34 is a module for throttle valve opening feedback correction, which compares the target throttle valve opening θ1 and the actual throttle valve opening Sa from the throttle sensor 22, calculates a correction coefficient 5aFB, and calculates the correction coefficient 5aFB. is output to the multiplier 35. Then, in the multiplier 35, the target throttle valve opening θ1 is multiplied by the correction coefficient 5aFB to perform feedback correction, and the target throttle valve opening after this feedback correction is output as 02 to the throttle actuator 7, The opening degree of the throttle valve 6 is controlled to the target throttle valve opening degree θ2.

Fuel control Next, to describe the fuel supply amount control system in FIG. 3, Ma5 is set to the air-fuel ratio (stoichiometric air-fuel ratio 14.7, i.e., input = i) set in advance for the accelerator operation amount α (as described later). A fifth map in which a target value Qfr of fuel to be supplied to the engine 1 is set so that the target amount of fuel Qfr to be supplied to the engine 1 in response to the output from the accelerator pedal position sensor 19 is determined according to the accelerator operation amount α. Qf1
This constitutes target fuel setting means 37 for setting.

MB6 is the air amount Qa set in the second map MA2.
The minimum fuel amount Qf for the engine coolant temperature TW is set so that the air-fuel ratio becomes the necessary air-fuel ratio for idle up with respect to m.
This is the sixth map in which a value of m is set, which receives the output of the water temperature sensor 23 and sets the minimum fuel amount Qfm for water temperature correction according to the engine coolant temperature Tw. 38 receives the respective outputs of the fifth map MBs (target fuel amount setting means 37) and the sixth map MB6, and calculates the target fuel amount Qf1 determined by the fifth map MBS and the water temperature correction determined by the sixth map MBs. The maximum value Qf2 of the minimum fuel amount Q f m
This is a maximum value selection circuit that selects the target fuel amount Qf.
1 is less than the minimum fuel amount for water temperature correction Qfm, the minimum fuel amount for water temperature correction Qfm is selected to increase the idle, thereby ensuring good engine operability.

MB7 is a seventh map in which the maximum fuel amount QfM for the engine rotation speed Ne is set so that the maximum air amount QaM set in the third map MA3 becomes a preset target air-fuel ratio; The maximum fuel amount QfM is set according to the rotational speed Ne. 39 receives each output of the maximum value selection circuit 38 and the seventh map M17, and selects the maximum fuel amount Qf2 determined by the maximum value selection circuit 38 and the maximum fuel amount QfM determined by the seventh map MB7. This is a minimum value selection circuit that selects the minimum value Qf3, and when the target fuel amount Qf1 exceeds the maximum fuel amount QfM determined by the engine speed Ne, that is, the target air amount Qal is determined by the engine speed Ne as described above. When the target value is an amount exceeding the maximum air amount QaM and the amount of air that can be taken in when the throttle valve 6 is fully open, the maximum air iQaM is selected so that the air-fuel ratio reaches the target air-fuel ratio even at that time. .

From the above, as in the case of air volume, accelerator operation amount α
, correction for engine cooling water temperature T%1 and engine rotation speed Ne! Target fuel amount Q considering button correction to maximum fuel amount with throttle valve 6 fully open determined by
Find f3.

The target fuel amount Qf3 signal from the minimum value selection circuit 39 is output to the fuel injection valve 12 via the divider 40, the first to third multipliers 41 to 43, and the fuel injection valve correction circuit 44.

The divider 40 receives the output from the minimum value selection circuit 39 and divides the target fuel amount Qf3 by the engine rotation speed Ne assuming that fuel is injected into two cylinders at the same time to calculate the fuel supply amount Qfi per cylinder. It is something to do.

The first multiplier 41 corrects the target fuel supply amount Qfi obtained by the divider 40 by multiplying it by an air-fuel ratio correction coefficient Cf for the accelerator operation amount α obtained from the eighth map MBg, which will be described later, to supply the target fuel. The quantity Qfi is calculated.

The second multiplier 42 multiplies and corrects the target fuel supply amount Qfi1 obtained by the first multiplier 41 by the correction coefficient CaFB obtained by the intake air amount correction module 46 to calculate the target value fuel supply amount Qfi2. It is something to do. This correction module 46 receives the signal of the target air amount Ac1 from the multiplier 32, and also receives the signal of the actual air amount QaR and engine rotation speed Ne actually measured by the air flow meter 20, and calculates the actual air amount. The actual air amount AcR per cylinder calculated from QaR and engine speed Ne is compared with the target intake air amount Ac1, and a feedback coefficient CaFB for feedback correcting the throttle valve opening is calculated according to the deviation. It is something.

The third multiplier 43 corrects the target fuel supply amount Q f i 2 obtained by the second multiplier 42 by multiplying it by the air-fuel ratio correction coefficient CfFB obtained by the feedback correction module 47 during lean operation. Then, the target fuel supply amount Qfi3 is calculated. This feedback correction module 47 includes the water temperature sensor 23 and the map MBg.
And in response to the output from the air-fuel ratio sensor 24, for example,
The engine cooling water temperature is 60℃ or higher, and the air-fuel ratio correction coefficient CF from MBg is the stoichiometric air-fuel ratio (entering at 14,7 = 1
), the map MB
The coefficient Cf for feedback correction is calculated and outputted so that the air-fuel ratio is set by .

The fuel injection valve correction circuit 44 receives the target fuel supply amount Qfi3@ from the third multiplier 43 and the battery voltage VB signal from the battery 28, and adjusts the target fuel to the fuel injection valve 12 according to the battery voltage VB. The pulse signal as the supply amount signal is corrected and output to the fuel injection valve 12.

As described above, a fuel control means is constructed which drives the fuel injection valve 12 for a predetermined period of time in synchronization with ignition and controls the air-fuel ratio to a target value as described in detail below.

Air-Fuel Ratio Control Next, the air-fuel ratio control portion of the above-described configuration that performs switching between lean and rich will be described with reference to FIG. 4.

First, in the present invention, switching between lean and rich is performed according to the accelerator operation amount α, and in the embodiment, the air-fuel ratio in lean operation is 22, and the air-fuel ratio in rich operation is 13. It's Toshide. And this lean,
As the rich boundary value, the accelerator operation amount α or the first predetermined amount α1 (MAl, MBs, MBg in Fig. 3, Fig. 4 (
C)), and the accelerator operation amount α
By setting a second predetermined amount α2 that is slightly smaller than this first predetermined amount α1 and a third predetermined amount α3 that is slightly larger than this first predetermined amount α1, α2 to α
1 is the first transition period, and α1 to α3 is the second transition period.
During the transition period, the air-fuel ratio is gradually changed as shown in FIG. 4(b).

Based on the above, when switching to rich operation, the opening degree of the throttle valve 6 is fully opened, so that the target air amount Qa1 for the accelerator operation amount α is changed as shown in the map MA1 in FIG. It is set so that it corresponds to (C). Then, the value of the smallest accelerator operation amount α at which the throttle is fully opened is set as the second predetermined amount α2. Of course, before the accelerator operation amount α becomes fully open, the throttle valve opening degree is set to increase in accordance with an increase in the accelerator operation amount α.

On the other hand, Fig. 3 map MB5. That is, the target fuel amount Qf 1 for the accelerator operation amount α is set so as to obtain a fuel amount that provides the stoichiometric air-fuel ratio with respect to the target air amount obtained from the map MA 1 .

Furthermore, the air-fuel ratio is changed using map MB8 in FIG. That is, this map MB is set to correspond to the one shown in FIG. 4(b),
The air-fuel ratio is set to 22 corresponding to lean operation when the accelerator operation amount α is less than the second predetermined amount α2, to the stoichiometric air-fuel ratio (input = i) when the accelerator operation amount α is less than the second predetermined amount α2, and to rich when the third predetermined amount α3 is set. It is set to 13, which corresponds to driving. From α2 through α1 to α3, the air-fuel ratio is gradually changed from 22 to 13.

Incidentally, the linear operation correction module 47 in FIG. 3 is for performing feedback control to accurately obtain the air-fuel ratio at least during operation at the above-mentioned air-fuel ratio 22 to 14.7 (input = 1). However, this feedback may be performed until or even after the transition to rich operation is complete.

In this way, in the present invention, the throttle valve opening is fully open when switching to rich operation, so the filling amount (intake air amount) is no longer a factor affecting the output fluctuation at this time. Only the fluctuation of the air-fuel ratio is included. Thereby, as shown in FIG. 4(a), it is possible to reduce output fluctuations when switching to rich operation. Of course, as in the embodiment, if the air-fuel ratio is gradually changed between lean and rich with the throttle valve opening fully open, output fluctuations can be further prevented.

Although the embodiments have been described above, the present invention is not limited thereto, and includes, for example, the following cases.

(2) As the fuel supply means, a carburetor may be used instead of the fuel injection valve 12, and in this case, the air-fuel ratio may be changed by adjusting various jets (including air jets) of the carburetor.

■The amount of fuel to obtain a predetermined air-fuel ratio is not determined directly according to the accelerator operation amount α, but is determined, for example, by the target intake air amount ACI in Fig. 3 or the target throttle valve opening θ.
It may be determined indirectly by 1 or 02, or furthermore, it may be determined according to the output from the air flow meter 20.

■Even if the elements of map MB8 are included in the map MBs in FIG. 3, and the fuel amount corresponding to the different air-fuel ratios depending on the accelerator operation amount α is calculated at the time of this map MBS. good.

■Lean and rich can be defined as relatively small or large air-fuel ratios, and are not necessarily stoichiometric air-fuel ratios (input = 1).
) is not limited to larger or smaller.

(2) When the control unit 25 is constituted by a microcomputer, it may be of either an analog type or a digital type.

(Effects of the Invention) As is clear from the above description, the present invention provides a system for switching between a rich operation with a high air-fuel ratio and a rich operation with a low air-fuel ratio according to the engine load. It is possible to reduce output fluctuations and obtain good drivability.

In addition, since switching between lean operation and rich operation is performed using the accelerator operation amount as a parameter,
In addition to being able to more accurately determine the switching point than in systems that utilize intake negative pressure, it is also possible to precisely control the air-fuel ratio before and after this switching point.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the present invention. FIG. 2 is an overall system diagram showing one embodiment of the present invention. FIG. 3 is a block diagram showing a control example of the present invention. FIG. 4 is a graph showing the relationship between accelerator operation amount, throttle valve opening, and engine output in the embodiment of the present invention. 1: Engine 2: Intake passage 5: Accelerator pedal 6: Throttle valve 7: Throttle actuator 12: Fuel injection valve 19: Accelerator sensor 25: Control unit 33: Target throttle valve opening determining means 45: Air-fuel ratio determining means

Claims (1)

[Claims] (1) an accelerator detection means for detecting an accelerator operation amount; a throttle valve control means that receives the output of the accelerator operation amount and causes the throttle valve to be fully open at least when the accelerator operation amount is equal to or greater than a predetermined amount; and an engine. receiving the output of the fuel supply means for supplying fuel to and the accelerator detection means, and controlling the fuel supply means;
An engine control device comprising: air-fuel ratio control means for changing an air-fuel ratio in response to an accelerator operation amount when the accelerator operation amount exceeds the predetermined amount.