JP3218565B2 - Irregular combustion detection method of body vibration reduction device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an apparatus for reducing vibration of a vehicle body due to engine rotation fluctuation due to irregular combustion (rough) during idling. It relates to a method for quickly and surely detecting.

[Conventional technology]

The conventional apparatus reduces the rotation speed detection error when measuring the interval between pulse signals corresponding to the rotation speed as described in Japanese Patent Application Laid-Open No. 60-190866. For this purpose, a process of ignoring abnormal values which are considered to have occurred due to electrical noise and mechanical element deviations is performed.

[Problems to be Solved by the Invention] The prior art described above does not take into consideration the occurrence of irregular combustion during combustion (a combustion defect that sometimes occurs and is hereinafter referred to as rough). There has been a problem in that it is not considered to detect it, and the problem to be solved by the present invention cannot be dealt with.

An object of the present invention is to provide an irregular combustion detection method capable of detecting a rough quickly and accurately.

To stop the unpleasant vibration transmitted to the vehicle body, it is necessary to bring the peak of the power generation torque at a timing that is half a cycle of the vehicle body vibration or the vibration of the engine itself from the occurrence of the rough, but when controlling the field current However, there is a problem that the control must be performed from a timing at which the rise of the torque is slow and early. The purpose of the present invention of early detection comes from that.

[Means for solving the problem]

According to the present invention, the crank angle at which the rotational speed fluctuation generated due to the rotational torque fluctuation of the engine becomes the maximum is obtained, for example, by an experiment in advance, and a signal for each "720 ° / number of cylinders" output from the rotational speed detector is used. The timing signal is generated from the angle signal, and the instantaneous rotational speed at that time is measured from the cycle of the angle signal.

Furthermore, the measured value is compared with the value measured immediately before,
When the rotation drop width exceeds a predetermined value, it is determined to be rough.

(Operation)

The engine speed is adjusted according to the number of cylinders, based on the effect of torque fluctuations caused by the intake, compression, explosion, and exhaust processes.
0 ゜ / number of cylinders ”. Therefore, even if there is no irregular combustion, the rotation speed is 20
It fluctuates by ~ 40rpm. Therefore, if the rotation speed is taken in ignoring the crank angle, the accuracy of detecting a rotation drop due to irregular combustion is significantly deteriorated. In the present invention, the error is eliminated because it is taken in synchronization with the crank angle.

Furthermore, since the comparison is made based on the number of rotations at the crank angle at the peak of the rotation fluctuation, the peak drop due to irregular combustion can be detected quickly and largely.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. Here, a four-cycle four-cylinder engine is representatively illustrated.

First, the overall configuration will be described with reference to FIG. Engine 1
The alternator 2 is connected to the motor, and the rotating shaft of the alternator and the crankshaft of the engine are connected by a belt. Further, an engine rotation detecting device 3 that outputs a pulse number proportional to the engine rotation speed is connected to the crankshaft of the engine 1. The engine 1 is connected to the vehicle body 5 via an engine mount formed of an elastic body.

Next, as a signal flow, the crank angle signal output from the engine rotation detecting device 3 and the 180 ° signal output every 180 ° (= 720 ° / number of cylinders 4) are divided into a signal fetch timing generating device 6 and a pulse The alternator control signal is input to the generated current control unit 4 including the cycle measuring device 7, the arithmetic device 8, and the booster circuit 9, and the alternator control signal is output to the alternator as an output.

Next, the irregular combustion will be described with reference to FIG. In a high-speed rotation type engine, if the load suddenly becomes light and becomes idle, combustion becomes unstable and the combustion pressure may not be sufficiently increased. This is referred to as irregular combustion (rough), only sections which rotational torque has decreased engine speed N _E will be writing drop. Therefore, the engine vibrates in a form excited in the roll direction. And, when the engine is placed on the vertical side like an FR car, the vibration is transmitted to the car body through the mount and causes resonance. This vibration has a low frequency of about 5 to 8 Hz, and gives a feeling of discomfort to humans. Since this vibration has a low frequency, it cannot be mounted even if a mass damper is attached.

The role of the control unit 4 shown in FIG. 1 is to detect the occurrence of irregular combustion as soon as possible, and to cause the vehicle body vibration or the vibration of the engine itself or the vibration of the engine itself to be in the opposite phase before the unpleasant resonance vibration is transmitted to the vehicle body. In this way, the alternator applies pulse-like torque fluctuation to the engine and stops it. The timing of applying this control is 1 / (1) of the body vibration or engine vibration or engine vibration from the occurrence of rough
Since it has no effect unless it is two cycles late, it does not work well with ignition timing control of engine control.

This embodiment describes a method for detecting irregular combustion (rough) quickly and reliably from the experimental results shown in FIGS. First, as an index of the degree of irregular combustion, the value calculated from the combustion pressure that P _i meter is used, FIG. 3 between the rotational fluctuation width ΔN and P _i fluctuation width at the timing according to the present invention Indicate that the love can be accurately detected by observing the drop in the rotation fluctuation.

Furthermore, how much time has passed since the occurrence of the rough can be determined by comparing the rotational fluctuation at the time of the occurrence of the rough with the previous rotational fluctuation for each crank angle. As shown in FIG. It can be seen that, after the peak position, the drop width of the rotation speed becomes large, so that the detection can be reliably performed.

This embodiment will be specifically described with reference to FIG. Since the engine speed is usually in the form of a mountain having a period of 180 ° as shown in (a), the crank angle at the peak position of the mountain as shown in (b) is the dashed line shown in (a). For example, a rotation angle is detected by taking in a crank angle signal each time a crank angle of BTDC 100 degrees during compression (a crank angle of 100 degrees BTDC) comes, and measuring its cycle. In calculation, the period may be used. Here, the difference from the previously acquired rotation speed is taken to calculate the drop amount ΔN. When there is no irregular combustion (rough), the drop amount ΔN falls within 10 rpm as the engine speed. However, when a rough occurs, a drop ΔN in the rotational speed as shown in FIG. 3 is detected according to the degree of the rough. Therefore, a control signal is sent to the alternator so that the peak of the generated torque comes at a timing of 1/2 cycle of the vehicle body vibration from the occurrence of the rough. Here, the voltage applied to the field coil may be increased by the booster circuit 9 in order to obtain a sudden torque fluctuation.

Crank angle signal used for detecting the rotational speed of the present embodiment, signal 2 ⁰ signal coming out of the crank angle signal The better even accuracy may be used as it is, if there is such a mechanical error, which is the dividing May be used.

Further, as an alternative to the present embodiment, the timing of rough detection is limited to the time of interruption of a reference signal, which is a reference signal for engine control, and even if the instantaneous rotational speed at that time is detected, it is sufficient if the reference is after the rotational fluctuation peak. .

Furthermore, as an alternative, it is also possible to measure the time between specific crank angles without calculating the rotation speed from the crank pulse period. However, in this case, the accuracy is improved by bringing the measurement section after the rotation fluctuation peak, but when the section is long, the measurement time is too long and the control timing cannot be met.

〔The invention's effect〕

According to the present invention, it is possible to reliably detect the irregular combustion (rough) at an early timing from the occurrence thereof, so that it is possible to meet the timing of issuing a command to increase the generated current to the alternator.

[Brief description of the drawings]

FIG. 1 is a diagram showing the overall configuration of one embodiment of the present invention, FIG. 2 is a diagram showing the relationship between various characteristics due to irregular combustion, FIG. 3 is a diagram showing the degree of irregular combustion obtained from experimental results, FIG. The figure shows the relationship between the detection timing and the certainty obtained from the experimental results, and FIG. 5 is a specific explanatory diagram of one embodiment. DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Alternator, 3 ... Engine rotation detection device, 4 ... Generation current control unit, 5 ... Car body, 6 ... Signal acquisition timing generation device, 7 ... Period measurement device, 8 ... ... arithmetic unit, 9 ... booster circuit.

──────────────────────────────────────────────────の Continued on the front page (72) Inventor Kenichi Nakamura 2520 Takada, Katsuta-shi, Ibaraki Co., Ltd.Sawa Plant, Hitachi, Ltd. Inside Hitachi Sawa Plant (72) Inventor Yuzo Kadokomu 502 Kandachicho, Tsuchiura-shi, Ibaraki Prefecture Inside Machinery Research Laboratory, Hitachi, Ltd. (72) Inventor Kei Murakami 2 Takaracho, Kanagawa-ku, Yokohama City, Kanagawa Prefecture Inside Nissan Motor Co., Ltd. (56) References JP-A-61-135936 (JP, A) JP-A-2-69075 (JP, A) JP-A-1-190922 (JP, A) JP-A-58-185937 (JP, A) JP-A-58-221169 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F 02D 45/00 362 F02B 75/06 F02B 77/08

Claims (3)

(57) [Claims] An engine, an alternator, a rotation detection device for detecting fluctuations in engine rotation during idling, and a control unit for receiving a signal from the rotation detection device and controlling a field coil current of the alternator. The vehicle body vibration reduction device detects the instantaneous rotation speed at the crank angle at which the rotation speed fluctuation generated due to the engine rotation torque fluctuation becomes the maximum for every 720 ° / cylinder, and calculates the difference from the previous value. Detecting the irregular combustion according to the result of calculating the irregular combustion. 2. The method of claim 1, wherein the instantaneous rotation speed is detected at a timing of interruption of a reference signal. 3. A method for detecting irregular combustion in a vehicle body vibration reducing apparatus according to claim 1, wherein the rotational speed is detected at crank angle intervals after the peak position of the rotational speed.