JPH0745848B2 - Engine controller - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine control device, and more particularly to a device for controlling engine vibration.

(Prior Art) Conventionally, various devices have been proposed to prevent illegal fuel such as misfiring as much as possible to maintain a good combustion state and emission of the engine. Correcting the air-fuel ratio when it deviates from an appropriate value (see Japanese Patent Publication No. 56-33569), or correcting the air-fuel ratio and ignition timing when misfire occurs by detecting engine vibration due to misfire. There are things I did.

However, with such a conventional device alone, when a relatively large engine vibration is generated due to a misfire or the like, even if the cause of the vibration such as the misfire is quickly eliminated by the correction control, the vibration itself is not easily attenuated rapidly. . In particular,
When a vibration that resonates with the drive system occurs at a relatively low frequency, this vibration is transmitted to the vehicle body without being damped for a long time. Such a tendency becomes remarkable at the time of deceleration when the engine is driven by the wheels, and gives a driver discomfort as so-called deceleration car backing. Therefore, in order to prevent the driver from feeling uncomfortable and improve drivability, it is desired to suppress the above vibration as quickly as possible.

(Object of the Invention) In view of such circumstances, the present invention provides an engine control device capable of promptly attenuating low-frequency engine vibration when it becomes large.

(Structure of the Invention) According to the present invention, a detection unit for detecting low-frequency vibrations of engine vibrations that are displaced around the crankshaft is provided, and the low-frequency vibrations are output at a predetermined level by receiving the output of the detection unit. When the vibration value is equal to or greater than the value, control is performed to reduce the engine output when the vibration direction is opposite to the rotation direction of the crankshaft, and increase the engine output when the vibration direction is in the same direction as the rotation direction of the crankshaft. Engine output control means for performing at least one of control and control is provided.

With this configuration, when the low-frequency engine vibration becomes large, the engine output is controlled so as to suppress the displacement of the engine due to the vibration at the same time as this vibration.

(Embodiment) FIG. 1 shows an apparatus according to an embodiment of the present invention. In the figure, 1 is an engine composed of a cylinder block 2, a cylinder head 3 and the like, 4 is a combustion chamber formed above a piston 5 in a cylinder of the engine 1, and an intake valve 6 is provided for the combustion chamber 4. An exhaust valve 7 and a spark plug 8 are provided. The ignition plug 8 is connected to an ignition control unit 11 including an igniter 9 and a distributor 10.

Reference numeral 12 is an intake passage, 13 is an exhaust passage, and the intake passage 12 has an air cleaner 14, an air flow meter 15, and a throttle valve.
16 and the fuel injection valve 17 are provided, and the throttle valve 16
A throttle opening sensor 18 for detecting the opening of the exhaust passage 13 is provided, and a lean sensor 19 and an exhaust purification device 20 are provided in the exhaust passage 13. Each signal from the air flow meter 15, the throttle opening sensor 18, the lean sensor 19, and the crank angle signal 21 and the cylinder identification signal from the sensors provided in the distributor 10 and the like.
22 is input to a control unit (ECU) 23 using a microcomputer or the like.

Further, 24 is a displacement sensor for detecting engine vibration by detecting displacement of the engine 1, and 25 is the above displacement sensor.
It is a bandpass filter that passes only low frequency components of the engine vibration detected by 24.
A detection unit that detects a low-frequency vibration that displaces around the crankshaft is configured. The output of the displacement sensor 24 and the output of the bandpass filter 25 are also input to the control unit 23.

The control unit 23 outputs a control signal to the ignition control unit 11 and the fuel injection valve 17 to perform normal engine control for controlling the ignition timing and the fuel injection amount according to the intake air amount, the operating state of the engine, and the like. It also includes an engine output control means 26 for suppressing engine vibration according to the engine vibration of low frequency components detected by the displacement sensor 24 and the bandpass filter 25. In this embodiment, the engine output control means 26 retards the ignition timing when the engine vibration for the low frequency becomes a predetermined value or more and the vibration direction is opposite to the rotation direction of the crankshaft. The ignition timing is controlled in synchronization with the vibration so that the engine output is reduced.

2A and 2B show engine vibrations detected by the displacement sensor 24 and the bandpass filter 25. The engine vibrations detected by the displacement sensor 24 are
Although it contains various frequency components as shown in FIG. 2 (a), after passing through the bandpass filter 25, vibrations of low frequency components as shown in FIG. 2 (b) are extracted.
In this embodiment, in order to effectively prevent so-called car backing due to resonance between the engine and the drive system at the time of deceleration, which is particularly poor in vibration absorption, the bandpass filter 25 uses the center frequency of vibration passing through the bandpass filter 25 as the drive system resonance. I try to match the frequency.

FIG. 3 is a flow chart showing a concrete example of the control operation of the engine output control means 26 by the control unit 23. In the control operation shown in this flow chart, the displacement due to the vibration of the engine has a positive direction in the direction opposite to the rotation direction of the crankshaft (the same direction in which the engine tends to be displaced by the reaction as the engine output increases).

In this flowchart, first, in step S ₁ , the engine displacement he (t) detected by the displacement sensor 24 is detected.
And crank angle θc (t) and cylinder identification K signals are input. Then, the strength of the engine vibration is determined by the root mean square ▲ ▼ of the engine displacement he (t) within a fixed time, and it is checked in step S ₂ whether the root mean square ▲ ▼ is smaller than a predetermined value. when the determination result is YES the flow proceeds to step S ₁₂ without performing the processing of steps S ₃ to S _11.

When the engine vibration is strong and the determination result in step S ₂ is NO, the displacement hef (t of the frequency component passing through the bandpass filter 25 having the center frequency V ₀ equal to the resonance frequency of the drive system is determined in step S _3. ), And in step S ₄ ,
Corrects the phase shift when passing through the bandpass filter 25. Next, in order to check whether the low frequency component is relatively large in the engine vibration, in step S ₅ , the displacement hef after passing through the bandpass filter 25 within a certain time
The ratio H between the root mean square (t) of (t) and the root mean square of the engine displacement () is obtained, and step S ₆
Then, it is checked whether or not the ratio H is smaller than the predetermined value β. And when the determination result is YES, that is because when the proportion of the other frequency components is large, poor effectiveness of control for suppressing low-frequency vibrations min, step without the process of step S ₇ to S ₁₁ Move on to S ₁₂ .

When the determination result in step S ₆ is NO, that is, when the ratio of the low frequency component is large, the predicted engine displacement hye (t) for the next ignition is calculated in steps S ₇ and S ₈ . In this case, the current time is t and the time until the next ignition is Δ
Let t be the time when the engine displacement he (t) has recently reached its maximum, and let th max be the phase θh at the time of the next ignition.
Is calculated as θh = (t + Δt−th max) · V ₀ · 2π (step S ₇ ), and the predicted engine displacement hye (t) is calculated as hye (t) = ▲ ▼ · cos θh (step S _8). ). Note that the hye (t) obtained by this equation is, to be precise, an expected value of the amount corresponding to the engine displacement at the time of the next ignition. I regard it.

Then, if the expected engine displacement hye (t) is determined to be greater than 0 in step S _9, step S _10, at _11, the expected engine displacement hye (t) retard amount calculated from the map according to △ The ignition timing of the cylinder to be ignited next is retarded by θ _SP . In this case, as shown in FIG. 4, the retard amount Δθ _SP is set to a larger value in advance as the predicted engine displacement hye (t) is larger, and is stored as a map. Thus, when the engine displacement is in the forward direction, that is, in the direction opposite to the rotation direction of the crankshaft, by retarding the ignition timing of the cylinder in which ignition is performed, the engine output is reduced in synchronization with the displacement in the above direction. , At other times, the ignition timing is not retarded.

In step S _12, S _13, so as to change the engine displacement maximum time th max examine the time when the engine displacement he (t) reaches a peak. Then, by returning, the processing from step S ₁ is repeated.

According to the control shown in the above flowchart, when the engine vibration for a low frequency equivalent to the resonance frequency of the drive system becomes large, the engine displacement due to the vibration is in the opposite direction to the rotation direction of the crankshaft, that is, the engine output. At the time when the displacement direction is the same as the increasing displacement direction, the engine output is reduced by the ignition timing retard control that is synchronized with this, and thereby the displacement in the above direction is controlled. Therefore, the action of suppressing the engine vibration for low frequencies works, and the vibration is quickly damped. According to this embodiment, in particular, at the time of deceleration where the vibration absorbing action is inherently poor, so-called car backing due to resonance with the drive system can be effectively suppressed even when low frequency vibration occurs due to misfire or the like. . Of course, not only during deceleration, but also during steady operation or the like, damping of low frequency vibrations is assisted.

In the above embodiment, the engine output is controlled by the ignition timing to suppress the low frequency vibration, and the engine output is reduced when the vibration is in the opposite direction to the rotation direction of the crankshaft. However, if the engine displacement due to vibration can be controlled with sufficient responsiveness, the air-fuel ratio,
The engine output may be controlled according to the vibration by the load of the alternator, the torque applied by the Tokule generating means using an alternator, a starter, or the like. Further, the engine output may be increased when the vibration is in the same direction as the rotation direction of the crankshaft.

Further, the control of the engine output according to the vibration can be performed not only for the vibration of the co-vibration frequency of the drive system but also for the low-frequency engine vibration within the range where the control can follow the engine displacement due to the vibration.

(Effects of the Invention) As described above, according to the present invention, when the engine vibration for a low frequency becomes large, the engine output is controlled in a direction of suppressing the vibration in synchronization with the vibration. When engine vibration corresponding to a frequency is generated, it can be quickly attenuated to improve driving feeling and drivability.

[Brief description of drawings]

FIG. 1 is a schematic view of the entire apparatus showing an embodiment of the present invention, and FIG.
FIGS. (A) and (b) are explanatory diagrams showing the waveforms of engine vibration and low-frequency vibrations thereof, FIG. 3 is a flowchart showing a specific example of control, and FIG. It is explanatory drawing which shows the setting value of the ignition timing retard amount. 1 ... Engine, 8 ... Spark plug, 11 ... Ignition control unit, 23 ... Control unit, 24 ... Displacement sensor,
25 …… Band pass filter, 26 …… Engine output control means.

Claims (1)

[Claims] 1. A detection means for detecting a low-frequency vibration of engine vibration that is displaced about a crankshaft is provided, and the low-frequency vibration becomes a predetermined value or more in response to an output of the detection means. When the vibration direction is opposite to the rotation direction of the crankshaft, the control to decrease the engine output and the control to increase the engine output when the vibration direction is in the same direction as the rotation direction of the crankshaft An engine control device comprising an engine output control means for performing at least one of the above.