JPS62203963A - Control device for engine - Google Patents

Abstract

PURPOSE:To improve driving and operating characteristics when low frequency component of engine vibration increases by controlling the engine output in the direction of suppressing the vibration by synchronizing the output with the vibration, thereby damping the low frequency component of the vibration rapidly. CONSTITUTION:A displacement sensor 24 detects displacement of an engine 1 and detects vibration of the engine 1. A band-pass filter 25 passes only low frequency component of the engine 1 vibration detected with the displacement sensor 24. A control unit 23, while performing ordinary engine control by outputting control signals to an ignition control part 11 and to a fuel injection valve 17, is equipped with a control means 26 for performing control according to the said low frequency component of the vibration of the engine 1. Namely the said means 26 controls ignition timing, when for instance the low frequency component becomes more than a specified value, by retarding the ignition timing when the direction of the vibration is opposite to the rotary direction of a crank shaft to decrease the output of the engine 1.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) Mizumoto's application relates to an engine control device, and particularly to a device for controlling engine vibration.

(Prior art) Various devices have been proposed to prevent improper combustion such as misfires as much as possible and to maintain good engine combustion conditions and emissions. The air-fuel ratio is corrected when it deviates from the appropriate value.
Alternatively, there is a system that detects engine vibration caused by a misfire and corrects the air-fuel ratio or ignition time 1111 when a misfire occurs.

However, with only conventional devices like this, when relatively large engine vibrations occur due to misfires, etc., even if the cause of vibrations such as misfires is quickly eliminated through correction control, the vibrations themselves are difficult to damp down rapidly. . especially,
When vibrations that resonate with the drive system occur at relatively low frequencies, these vibrations are transmitted to the vehicle body without being damped for a long time, and this tendency is noticeable during deceleration when the engine is being driven by the iJi wheels. This results in so-called deceleration car backing, which causes discomfort to the driver. Therefore, in order to prevent discomfort to the driver and improve drivability, it is desirable to suppress the above-mentioned vibrations as quickly as possible.

(Object of the Invention) In view of the above-mentioned circumstances, the present invention provides an engine control device that can quickly attenuate low-frequency engine vibrations when they become large.

(Structure of the Invention) The present invention provides a detection means for detecting low frequency vibrations that are displaced around the crankshaft among engine vibrations, and receives the output of the detection means to detect vibrations of the low frequency portion in a predetermined manner. When the value exceeds the specified value, the engine output is controlled to be reduced when the vibration direction is in the opposite direction to the crankshaft rotation direction, and the engine output is increased when the vibration direction is in the same direction as the crankshaft rotation direction. An engine output control means is provided to perform at least one of the following:

With this configuration, when low-frequency engine vibrations become large, engine output is controlled in synchronization with the vibrations so that displacement of the engine due to the vibrations is suppressed.

(Embodiment) FIG. 1 shows an apparatus according to an embodiment of the present invention. In this figure, 1 is an engine composed of a cylinder block 2, a cylinder head 3, etc., 4 is a combustion chamber formed above a piston 5 in the cylinder of the engine 1, and an intake valve 6 is connected to this combustion chamber 4. , an exhaust valve 7 and a spark plug 8.

The spark plug 8 is connected to an ignition control section 11 that includes an igniter 9, a distributor 10, and the like.

12 is an intake passage, and 13 is an exhaust passage. The intake passage 12 is provided with an air cleaner 14, an air flow meter 15, a throttle valve 16, and a fuel injection valve 17, and the opening degree of the throttle valve 16 is detected. The exhaust passage 13 is also provided with a lean sensor 19 and an exhaust purification device 20. Signals from the air flow meter 15, throttle opening sensor 18, and lean sensor 19, as well as a crank angle signal 21 and a cylinder identification signal 22 from sensors provided in the distributor 10, etc., are sent to a control unit (using a microcomputer, etc.). ECU
)23.

Further, 24 is a displacement sensor that detects engine vibration by detecting the displacement of the engine 1, and 25 is a bandpass filter that passes only the low frequency component of the engine vibration detected by the displacement sensor 24. , a detection means is configured to detect low frequency vibrations that are displaced around the crankshaft. Then, the output of the displacement sensor 24 and the bandpass filter 25
The output through is also input to the control unit 23.

The control unit 23 outputs a control signal to the ignition control section 11 and the fuel injection valve 17, and adjusts the ignition timing and fuel injection OA according to the amount of intake air, the operating state of the engine, etc.
It includes an engine output control means 26 that performs normal engine control to control suspension, and suppresses engine vibrations in response to low frequency engine vibrations detected by the displacement sensor 24 and bandpass filter 25. In this embodiment, this engine output control means 26
is designed to retard the ignition timing and reduce the engine output when the low frequency engine vibration exceeds a predetermined value and the direction of the vibration is opposite to the direction of rotation of the crankshaft. The ignition timing is controlled in synchronization with the above vibration.

FIGS. 2(a) and 2(b) show engine vibrations detected by the displacement sensor 24 and band-pass filter 25, and the engine vibrations detected by the displacement sensor 24 have various effects as shown in FIG. 2(a). Although it contains frequency components, after passing through the band pass filter 25, low frequency component vibrations as shown in FIG. 2(b) are extracted.

In this embodiment, in order to effectively prevent so-called car bagging caused by resonance between the engine and the drive system during deceleration, which is particularly poor in vibration absorption, the band-pass filter 25 sets the center frequency of the vibration it passes to the drive system resonance frequency. I'm trying to match it.

FIG. 3 shows a specific example of the control operation by the control unit 23 as the engine output control means 26 in the form of a flowchart. In addition, in the control operation shown in this flowchart, the displacement due to engine vibration is in the opposite direction to the rotation direction of the crankshaft (in the same direction as the direction in which the engine attempts to displace due to reaction as the engine output increases).
is in the positive direction.

In this flowchart, first, in step S1,
Engine displacement he(
t), crank angle θc(t), and cylinder identification signals are input. Then, the strength of engine vibration is calculated as the root mean square of the engine displacement he(1) within a certain period of time h e(t
), and in step S2 the above root mean square h e(t)
is smaller than a predetermined value, and the determination result is YE.
If S, the process moves to step Sa without performing steps 83 to S11.8 If the engine vibration is strong and the determination result in step S2 is NO, in step S3, the process proceeds to step Sa, which is equal to the resonance frequency of the drive system. Displacement haf(
1) is input, and in step S4, the phase shift when passing through the band pass filter 25 is corrected. Next, in order to check whether the above-mentioned low frequency component is relatively large in the engine vibration, in step S5, the displacement her(t) after passing through the band pass filter 25 within a certain period of time is determined.
The ratio H between the root mean square h ef(t) of the engine displacement and the root mean square h e(t) of the engine displacement is determined, and in step S8 it is checked whether the ratio 1'' is smaller than a predetermined value β. When the determination result is YES, that is, when the proportion of other frequency components is large, control for suppressing low frequency vibrations is not effective, so the process proceeds to step S12 without performing steps 87 to S11. Move.

When the determination result in step S6 is No, that is, when the proportion of the low frequency component is large, steps S7 and S
Expected engine displacement hye(t) at the next ignition at a
Calculate. In this case, if the current time is t1, the time until the next ignition is Δt, and the time when the engine displacement h e(t) has recently reached its maximum is thmax, then the phase θh at the next ignition is θh = (t+△t-tt+ max) -VO (step $7), and from this, the above expected engine displacement 1ye(t) is hye(t) = hef(t) -cosθh
(Step Sa).

Next, in step S9, the predicted engine displacement hwe(t
) is larger than 0, step S1o,
At S1t, the ignition timing of the cylinder to be ignited next is retarded by the retard angle m80sP determined from the map according to the expected engine displacement h ye (t). In this case, the above retard angle m△θ
8. As shown in FIG. 4, is set in advance such that the larger the predicted engine displacement h ye (t), the larger the value, and is stored as a map. In this way, by retarding the ignition timing of the cylinder in which ignition occurs when the engine displacement is in the positive direction, that is, in the opposite direction to the rotational direction of the crankshaft, the engine output is reduced in synchronization with the displacement in the above direction. , otherwise at the time of ignition) Il′l
Don't delay.

Next, step S12. In Sn, engine displacement he(1)
When t'h wax reaches its peak, the time t'h wax is checked and the time t'h wax at which the engine displacement is excessive is updated.

Then, by returning, the processing from step S1 is repeated.

According to the control shown in the above flowchart, when the engine vibration at 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 Engine output is reduced by retard control of the ignition timing in synchronization with the displacement direction during increase, thereby suppressing displacement in the above direction. Therefore, the effect of suppressing engine vibrations at low frequencies is activated, and photographing is quickly damped. According to this embodiment, it is possible to effectively suppress so-called car bagging due to resonance with the drive system, especially when low-frequency vibrations occur due to a misfire or the like during deceleration, which is inherently poor in vibration absorption. Of course, the damping of low frequency vibrations is assisted not only during deceleration but also during steady operation.

In the above embodiment, the engine output is controlled by the ignition timing to suppress low frequency vibrations, and the engine output is reduced when the vibration is in the opposite direction to the rotational direction of the crankshaft. However, if engine displacement caused by vibration can be controlled with sufficient responsiveness, engine output can be controlled in response to vibrations using the air-fuel ratio, alternator load, and torque applied by a torque generating means using an alternator, starter, etc. It's okay. Further, the engine output may be increased when the vibration is in the same direction as the rotational direction of the crank 'In.

Furthermore, control of engine output in response to vibrations can be performed not only for vibrations at the resonant frequency of the drive system but also for low-frequency engine vibrations within a range where control can follow engine displacement due to vibrations.

(Effects of the Invention) As described above, the present invention controls the engine output in a direction that suppresses photography in synchronization with the vibration when the low frequency engine vibration becomes large. When low-frequency engine vibrations occur, they can be quickly attenuated to improve driving feeling and drivability.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of the entire device showing an embodiment of the present invention;
Figures (a) and (b) are explanatory diagrams showing waveforms of engine vibrations and low-frequency vibrations, Figure 3 is a flowchart showing a specific example of control, and Figure 4 is based on the expected engine displacement used in the above flowchart. FIG. 2 is an explanatory diagram showing set values of the ignition timing retard direction. DESCRIPTION OF SYMBOLS 1... Engine, 8... Spark plug, 11... Ignition control part, 23... Control unit, 24...
・Displacement sensor, 25...Band pass filter, 26
...Engine output control means. Patent applicant Mazda Corporation No. 1
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Claims (1)

[Claims] 1. Provide a detection means for detecting low-frequency vibrations that are displaced around the crankshaft among engine vibrations, and upon receiving the output of this detection means, when the low-frequency vibrations exceed a predetermined value, At least one of control for reducing engine output when the vibration direction is in the opposite direction to the rotation direction of the crankshaft and control for increasing engine output when the vibration direction is in the same direction as the rotation direction of the crankshaft. 1. An engine control device comprising an engine output control means for controlling the engine output.