JPH01178753A - Engine controller - Google Patents

Abstract

PURPOSE:To improve a travel feeling in an automatic cruise state by making the variable speed of a combustion control parameter lower than at the time of a nonautomatic cruise when an automatic cruise in the case. CONSTITUTION:Feedback compensation for a fuel injection quantity in a control unit 20 takes place in the shape of correcting a compensation factor by a proportional term first, then by integral term at each time output of an oxygen sensor 18 is selected to the lean side from the rich side and vice versa. In an automatic cruise state hereat, these proportional and integral terms are set to be small. With this constitution, at the time of an automatic cruise, variable speed of the fuel injection quantity is made so as to be abated by lowering a gain of air-fuel ratio feedback. Consequently, a torque variation in an engine 1 in the automatic cruse state becomes lessened, so that a travel feeling is made so better.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an engine control device for a vehicle equipped with an auto cruise device (automatic constant speed traveling device).

(Prior Art) In engine combustion control, it is generally necessary to change control parameters such as fuel injection amount and throttle opening with good responsiveness according to the operating state of the engine.

For example, in a control that maintains the air-fuel ratio at an optimal value by controlling the fuel injection amount based on the output of the 02 sensor that detects the oxygen concentration in exhaust gas, if the responsiveness of feedback correction is poor, the accelerator When the engine is depressed, the amount of fuel injection does not increase easily even though the amount of intake air increases.
In particular, if the rate of change in throttle opening is large, accurate air-fuel ratio control cannot be performed. Therefore, when controlling the Ennon, settings are usually made to increase responsiveness as much as possible.

However, such high responsiveness of Enson control may not necessarily be advantageous in some cases. For example, if the driver wants to drive the car at a constant speed without adjusting the accelerator, he or she will subtly adjust the amount of pressure on the accelerator to maintain a constant speed. , it is rather difficult to keep the vehicle speed constant because a slight change in the throttle will immediately result in a change in vehicle speed. Therefore, for constant speed running, it is more convenient to reduce the responsiveness of the control to some extent. but,
If the response of engine control is poor, accurate control cannot be performed when the throttle opening is greatly depressed. In addition, when the auto cruise device is activated to automatically drive at a constant speed, all combustion controls including throttle control are performed automatically without the driver's intervention. There is a phenomenon in which small shocks caused by torque fluctuations are felt more sensitively than during operation. And if the control response is good, the shock caused by such torque fluctuations in auto-cruise mode becomes rather large, which creates a problem with the feeling of the vehicle.

(Object of the Invention) The present invention has been made in view of the problem described in item 1 in engine control during constant speed driving, and an object of the present invention is to improve the driving feeling at least in an autocruise state.

(Structure of the Invention) In the present invention, since sudden throttle operation is not performed in the auto-cruise state, the responsiveness of the engine control can be reduced to a certain extent only in the auto-cruise state; This is based on the knowledge that reducing responsiveness to a certain extent makes it easier to maintain a constant vehicle speed, and also reduces torque fluctuations, improving driving feeling.The overall configuration is shown in Figure 1. As shown below. That is, the engine control device according to the present invention includes an operating state detection means for detecting the operating state of the engine, and a control parameter setting device for setting the magnitude of a control parameter that determines the combustion state of the engine according to the operating state of the engine. means, a combustion state control means for controlling the combustion state of the ennon based on set control parameters, an autocruise state detection device for detecting the autocruise state, and a combustion state control means for controlling the combustion state of the ennon based on set control parameters; The present invention is characterized by comprising a change speed reducing means for reducing the change speed of the control parameter.

(Function) During normal operation (not in auto-cruise state) (J, combustion control parameters are set according to the normal rate of change depending on the operating state of the engine, and the combustion state control means operates based on them. On the other hand, during auto-cruise state , the rate of change of the control parameters is reduced compared to when non-autocruise, so the responsiveness of combustion control is reduced.

In this state where the responsiveness of combustion control is reduced, engine torque fluctuations are reduced, so the shock felt by the driver during autocruise is reduced.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 2 is an overall view of an embodiment of the present invention.

In this embodiment, an engine 1 includes a cylinder block 2, a cylinder head 3 disposed in a portion thereof, and a piston 5 that reciprocates within a cylinder bore 4. An intake boat 7 and an exhaust port 8 that open into the combustion chamber 6 are formed in the engine cylinder head 3, and an intake valve 9 and an exhaust valve IO are disposed in these openings, respectively. Further, a spark plug 11 is installed in the upper center of the combustion chamber 6.

An intake passage 12 is connected to the intake boat 7, and a fuel injector 13 is disposed in the intake passage 12 near the intake boat 7, and a throttle valve 14 is disposed upstream thereof. Further, an air flow meter 15 is provided upstream of the throttle valve 14.

An exhaust passage 17 equipped with a catalyst device 16 is connected to the exhaust port 8, and a sensor 18 is connected to the upstream side of the catalyst device 16.
is installed.

The control unit 20 that controls the throttle valve 14 via the injector 13 and the electric actuator 19 includes an opening signal of the throttle valve 14, an intake air amount signal from the air flow meter 15, and an air-fuel ratio signal from the 02 sensor 18. In addition to various signals indicating the operating state of the engine, such as a rotational speed signal, a vehicle speed signal, and an accelerator opening signal from the sensor 21, an autocruise signal indicating whether or not the vehicle is in an autocruise state is input. Then, depending on whether or not the auto-cruise state is in effect, fuel injection amount control is performed by changing the air-fuel ratio feedback gain.
Throttle control is performed during autocruise and non-autocruise.

The fuel injection amount is determined by adding 0 to the basic injection m based on the engine speed and intake air amount. It is calculated by adding feedback correction based on the output of the sensor and further adding correction for invalid injection time according to the battery voltage. Feedback correction changes the output of the 02 sensor from the ridge side to the lean side,
Moreover, each time the switching is reversed, the correction coefficient is first corrected by the proportional term (P value) and then by the integral term (■ value). In auto cruise mode, this P
value and I value are set small. In other words, during autocruise, the speed of change in the fuel injection amount is reduced by lowering the gain of the air-fuel ratio feedback.

The throttle valve 14 is controlled when the vehicle is not in the auto-cruise state by outputting a throttle opening signal to the electric actuator 19 in accordance with the accelerator opening. In the autocruise state, the set target vehicle speed is compared with the actual vehicle speed, and the throttle opening is increased or decreased by a predetermined amount depending on the magnitude of the comparison, thereby maintaining a constant vehicle speed.

Next, a flowchart for executing such control will be explained with reference to FIG. In the figure, 81 to S3 indicate each step.

First, the engine speed and intake air amount are measured (S2), and then the pulse width PWS corresponding to the basic fuel injection amount is determined based on these measured values. Calculate (S3)
.

Next, in S4, it is checked whether the switch indicating the auto cruise state is turned on. Then, if the auto cruise switch is on, set the flag to 1 in S5,
Also, if it is turned on, the flag is set to O in S6.

Then, in step S7, the throttle opening degree and engine speed are read, and it is determined in step 88 whether or not the feedback zone is set by the throttle opening degree and engine speed.

If it is not the feedback zone, go to S, set the feedback correction coefficient to zero, and proceed as is.

If it is a feedback zone, then S. Go to and see if the flag is 1. Then, if the flag is 1, that is, auto cruise, S
In step 11, set the P value of the feedback correction to Pl, and
Set the value to 1. Set to . Also, if the flag is not 1,
In S12, the P value is set to P2 and the 1 value is set to 12.

Here, P+<P2, II<I2.

8. Next, in S13, it is determined whether the output of the 02 sensor is 1, that is, whether the air-fuel ratio is in a rich state or a lean state.

If the output of the 02 sensor is 1, that is, the rich state, then in SI4 it is determined whether or not the moment when the output of the 02 sensor changes from zero to 1 is reached. Then, when it is the moment when it changes from zero to 1 (YES), go to S + □ and set the foot bank correction coefficient CF.
Reduce B by P, and if it is not the moment when it changes from zero to 1 (NO), go to S16 and change CFB.
Reduce by ■.

Further, if the output of the 02 sensor is not 1, that is, the lean state, the process goes to SI7, and it is determined whether the output of the 02 sensor has changed from 1 to zero. Then, if it is the moment when it changes from ■ to zero (YES), go to SI8 and increase CFB by P, and if it is not the moment when it changes from l to zero (No), go to S1□ Go to and increase CFB by 1.

And S. Then, the pulse 11 P W S corresponding to the final injection amount is calculated, and the injection is executed.

The final injection pulse lil P W S is determined by adding a correction term obtained by multiplying the basic injection pulse width PWSO by the feedback correction coefficient CFB, and further adding the invalid injection time τBAT.

Next, in S21, it is determined whether the flag is 1, and if the flag is l (YES), the target vehicle speed is set to ■ in S22 in order to perform auto cruise control. Then, in S, 3, set the target throttle opening θ based on ■o.
Set up TVO. Then, read the vehicle speed V in S2 A, go to S, 5, and ■ is V. Determine whether it is greater than.

Then, the vehicle speed V is the target vehicle speed■. If it is higher (YES), go to S and G and set the target throttle opening △θ.
Lower it. Also, the vehicle speed ■ is the target value ■. If it is not reached (NO), then S 2'l and then V.

It is determined whether the target throttle opening degree is lower than that, and if it is low (YES), the process goes to S28 and the target throttle opening degree is increased by Δθ. When the answer is No in S 5 and No in S 2G, this means that the vehicle speed has reached the target vehicle speed, so the target throttle opening set in S 23 is not corrected.

If the flag is not 1 (NO) in S21, that is, the auto cruise state is not in effect, go to 82B, read the accelerator opening e ACC, and read the accelerator opening e ACC, and set θ9° in S3CI. Calculate the target throttle opening according to.

Next, go to S32 and set the target throttle opening to 0TV.
A throttle control signal is output so that the value becomes O, and the -th control is completed. Then, repeat this.

In this embodiment, the fuel injection amount is controlled to maintain the engine's air-fuel ratio at an optimum value. However, the present invention is also applicable to the control of the electrically driven throttle valve during autocruise mode. The present invention can also be applied to various other control parameters for combustion control, such as slowing down the speed of change in opening degree.

By the way, the present invention has two parts: main and 1. In order to improve the driving feeling in the auto-cruise state, the rate of change of control parameters in combustion control during auto-cruise is reduced,
Basically, in auto-cruise mode, there is no need to assume that the accelerator pedal is suddenly depressed and the throttle opening changes suddenly. This is based on the premise that the conditions for control can be relaxed, and that by relaxing the transient response during autocruise, the engine characteristics during autocruise can be improved. However, the technical idea based on this recognition can also be applied to ignition timing control during autocruise, as described below.

In an engine, engine speed N and intake air amount Q
There is an ideal ignition timing (M B T ) corresponding to this, and MBT can be determined using a map whose coordinate axes are N and TI) (Q/N). However,
If ignition timing is controlled based on such an MBT map, knocking is likely to occur when the accelerator is suddenly depressed in the medium load range, so in reality, knocking does not occur during such transients. The ignition timing is determined based on a map obtained by retarding each value of the MBT map. However, when the vehicle is running in an auto-cruise state, there is a low probability that the throttle opening will change significantly as in a general transient state, so it is not necessary to retard the ignition timing as described above.

Therefore, only during autocruise, ignition control may be performed using the MBT map or by reducing the amount of retard. As a result, during autocruise, if the fuel injection amount is the same, engine torque increases, so the fuel injection amount can be reduced by that amount.
Therefore, fuel efficiency is improved.

(Effects of the Invention) Since the present invention is configured as described above, torque fluctuations in the auto-cruise state are reduced, and the driving feeling is improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall configuration diagram of the present invention, FIG. 2 is an overall diagram showing an embodiment of the present invention, and FIG. 3 is a flowchart for executing control of the embodiment. 1 engine, 13 injector, 14. Throttle valve, 15 Air flow meter, 180, Sensor, 20・
Control 1 - Roll unit, 21° rotation sensor. Agent Patent Attorney Jun Shinfuji - Figure 1

Claims (1)

[Claims] (1) Operating state detection means for detecting the operating state of the engine; control parameter setting means for setting the magnitude of a control parameter that determines the combustion state of the engine according to the operating state of the engine; combustion state control means for controlling the combustion state of the engine based on the
Engine control characterized by comprising: an autocruise state detection device that detects an autocruise state; and a change speed reducing means that reduces the change speed of the control parameter when the autocruise state is detected. Device.