JPS58174153A - Injection timing sensing device of engine - Google Patents

Abstract

PURPOSE:To facilitate the dynamic injection timing sensing and secure the sensing with satisfactory accuracy by taking out amonmg the output signals of a vibration sensor only those signals which range in frequencies from 100 to 400kHz and by performing the sensing of the inejction start timing upon subjecting those signals to amplification treatment. CONSTITUTION:The fuel pipe 1 is equipped with a piezo element 2 to sense vibrations. Judgement of the injection start timging can be made possible by taking out only signals ranging in frequencies from 100 to 400kHz and subjecting them to an amplification treatment. The vibratory level of the injection valve's opening and closng for the cylinder fitted with a vibrosensor 13 is output in a larger scale than levels of vibrations due to opening/closing of injection valves for the other cylinders, so that the output pulses from a comparator 24 can serve for discrimination of this cylinder.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to an injection timing detection device that electrically detects fuel injection timing in an internal combustion engine, particularly a diesel engine, and measures its advance angle.

(Prior art) One of the conventional methods of determining injection timing is to use a dial gauge, which is adjusted so that the reading on the dial gauge is within a predetermined range by manually turning the crankshaft. It is something to do. This method statically adjusts using the dial gauge reading as a guide, so
It is not possible to obtain accurate injection timing, and the only way to determine the dynamic injection timing while the engine is rotating is to make an analogy.
In the end, accurate injection timing cannot be obtained.

Another conventional example is Japanese Patent Laid-Open No. 55-5477.

This is achieved by attaching a vibration sensor to the delivery pipe that connects the fuel injection valve and injection pump, and by selecting the natural vibration frequency of the sensor to be between 100 KHz and 10 MHz. There is a system that measures rotational speed, etc., and injection timing by detecting only the vibration when the delivery pipe is pressurized, out of the vibrations that are a combination of the vibrations of the injection valve and the opening/closing vibrations of the injection valve. According to this conventional example, the vibration frequency due to the engine and piston is 5H.
The vibration frequency of the fuel pump and delivery pipe is said to be 100 KHz to 1σMHz. In this way, by selecting a sensor with a specific resonance frequency of IQ O) G (z ~ IQ MHz, which is generated by pressurizing the delivery pipe), only the pressurized vibration when the delivery pipe is opened can be detected. However, it is difficult to select a sensor with a natural frequency suitable for each injection system, and
At frequencies above KHz, it is difficult to clearly detect the vibration of the injection valve when it closes, and it is difficult to distinguish it from this.
G(z or higher), there are problems such as unnecessary vibrations and noise electromagnetic waves being mixed in.

(Objective of the Invention) The present invention has been made by focusing on such conventional problems.
It is an object of the present invention to solve the above problems by providing an injection timing detection device that extracts and amplifies the vibration signal of z and detects the injection timing from the amplitude of the processed signal.

Another object of the present invention is to obtain a voltage value corresponding to the engine rotational speed from the detection signal by the above-mentioned device and to be able to electrically set an advance angle value, and to set a timing light at the set angle. An object of the present invention is to provide an injection timing detection device that provides a signal for lighting up the engine, so that the advance value of the injection start timing can be seen during engine operation.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an example of mounting a vibration sensor, and FIG. 2 is a diagram illustrating the principle of injection timing detection according to the present invention.

In Figure 1, 1 is a fuel pipe, 2 is a piezoelectric element that detects the vibration of the fuel pipe, 3 is a fixture for attaching the piezoelectric element to the fuel pipe, and 4 is an output that outputs a vibration signal detected by the piezoelectric element. It is a terminal.

FIG. 2 shows the state of the vibration signal detected with respect to the amount of change in the needle pulp of the injection valve in the above configuration. In FIG. 2, (a) shows the amount of change in the needle pulp of the injection valve, and fuel injection starts at injection start time 10 and stops at injection end time 11. Waveform (bl is the vibration waveform for a size-type injection pump, waveform (C) is the vibration waveform for a distribution-type injection pump, waveform (1) is the waveform (the vibration waveform from which the low frequency components of bl below 10KH2 are removed, Waveform (el is a vibration waveform obtained by removing the low frequency component of 10KHz or less from waveform (C), waveform (f) is the waveform for a distribution injection pump (frequency component 100K in cl) (z ~ 40
This is a vibration waveform obtained by extracting and amplifying only the 0 KHz signal.

As is clear from the waveforms (b) and (d), in the case of a size-type injection pump, it is possible to determine the injection start time and end time even if the frequency below 10 KHz is removed, but in the case of a distribution-type injection pump, As is clear from the waveforms (C1 and (e), it is impossible to distinguish. However, even in the case of the distribution type, as shown in the waveform (fl), the frequency range is 100 KHz to 4
By extracting and amplifying only the 00 KHz signal, it becomes possible to determine the injection start timing. In this case, although the format is not shown, it can be determined from the beginning, so by extracting only the frequency of 100 KHz to 400 KHz, the injection timing can be determined regardless of whether a format or distribution type injection pump is used. be able to detect. In addition, the valve closing vibration signal of the injection valve is 100K) (
Detection is possible not only in the range of z to 400 KI (z) but also at several tens of KHz.

Based on this viewpoint, the present invention provides an injection timing detection device for a diesel engine.

FIG. 3 is a block diagram showing one embodiment of the present invention, and FIG. 4 is an operation time chart of FIG. 3.

In Fig. 3, 13 is a vibration sensor attached to the diesel engine body or the fuel injection system, for example, as shown in Fig. 1, and 14 is an amplifier, which has a frequency characteristic of -3 dB attenuation at a frequency of 500 KHz, as shown in Fig. 6. It amplifies the output of the sensor 13 with a frequency of 400) G(z or less. 15 is a bypass filter that attenuates the output of the amplifier 14 with a frequency of 100 KHz or less.

Reference numeral 16 denotes a maximum value detection circuit having a predetermined time constant, which detects the maximum value of the output signal of the filter 15 and attenuates it with the predetermined time constant. 17 compares the output of the maximum value detection circuit 16 with a predetermined comparison voltage value, and a comparator 18 that gives a pulse output when the output of the circuit 16>comparison value is triggered by the rising edge of the pulse of the comparator 17 and generates a constant short pulse. It is a monostable circuit that outputs pulses.

A maximum value detection circuit having a time constant longer than the attenuation time constant of the maximum value detection circuit 16 detects the maximum value of the filter 15 and attenuates it with a longer time constant. U is a comparator, which compares the voltage obtained by dividing the output of the maximum value detection circuit with the resistor R7 and the output of the maximum value detection circuit 16, and calculates the output of the circuit 16.
Gives pulse output with divided voltage. This pulse output represents a cylinder discrimination signal.

That is, since the injector opening/closing vibration level of the cylinder to which the vibration sensor 13 is installed is larger than the injector opening/closing vibration level of other cylinders, the output pulse of the comparator determines this cylinder.

19 is a charging circuit that charges the capacitor C with a constant current; and a sample and hold circuit that holds the new charging voltage of the capacitor C according to the output signal of the monostable circuit 18.

21 is a discharge circuit for capacitor C, 22 is a monostable circuit 18
The discharge circuit 21 is driven by the delay circuit which delays the output signal of the circuit for a predetermined period of time.

Since the charging voltage of the capacitor C is discharged in synchronization with the operation of the injection valve of each cylinder, the discharge voltage shows a voltage value corresponding to the engine speed. Then, since the voltage immediately before being discharged is held by the sample and hold circuit, a voltage corresponding to the engine rotation speed can be obtained from the circuit.

Reference numeral 5 denotes a lead angle setting section, which divides the voltage corresponding to the engine rotation speed from the sample and hold circuit with a resistor R8 and a variable resistor R4, and electrically sets an arbitrary lead angle value by adjusting the variable resistor R4. For example, if the resistor R5 is set to 15Ω and the variable resistor R4 is set to 3Ω, the rotation angle from injection to injection is 180 degrees, so the variable range of the variable resistor R4 is from O to the leap degree. The comparator compares the voltage obtained by the lead angle setting section 5 with the voltage of the capacitor C, and the output of the lead angle setting section 6 is
A pulse output is given by the voltage of the capacitor C, and the lead angle setting section 5
Reveal the point in time set in . υ is a monostable circuit,
It is triggered by the rising edge of the comparator's output pulse and outputs a short pulse signal.

Reference numeral 4 designates a flip-flop, which uses the cylinder discrimination signal of the comparator as a set input, uses the output of the comparator 17 as a reset input, and outputs a pulse signal having a time width from the time when the cylinder discrimination signal is generated to the time when the next injection starts.

4 is an AND circuit which receives the output of the flip-flop array and the output of the monostable circuit n, both of which provide an output at n1n, and supplies a signal to OUT to turn on the timing light.

Next, the operation of the above configuration will be explained using the operation time chart of FIG. 4.

The vibration signal obtained by the vibration sensor 13 is sent to the amplifier 14 and
4. After passing through 15, the waveform (100 KHz shown in Al
It is considered to be a signal in a frequency band of ~400KHz. In addition,
Waveform (code on AlO (#2.#1.#3.#4.#2
) represents each cylinder.

The output signal of the filter 15 is applied to a maximum value detection circuit 16 and another maximum value detection circuit, and outputs a signal of waveform (B). Waveform (In Bl, the triangular waveform drawn with a solid line is the output signal of the maximum value detection circuit 16, and the almost linear waveform drawn with a dashed line at the top is the output signal of another maximum value detection circuit. The output of the maximum value detection circuit 16 is compared with the comparison voltage (supplement) by the comparator 17, and the comparator 17 outputs the waveform (D).The monostable circuit 18 detects the rising edge of the waveform (D). The output of another maximum value detection circuit is divided by resistors Ft and R2 (as shown in waveform (B)). The output of the maximum value detection circuit 16 is compared with the output of the maximum value detection circuit 16 in the comparator, and the cylinder discrimination signal (signal waveform (C
)) is output.

The output (waveform CF, 1) of the monostable circuit 18 described above is applied to a sample and hold circuit, and is also applied to a delay circuit 22.
given to. The delay circuit n is the output of the monostable circuit 18 (
The waveform (E)) is delayed by a predetermined time period A (waveform (F)), thereby driving the discharge circuit 21 of the capacitor C. On the other hand, since the sample and hold circuit is directly driven by the output of the monostable circuit 18, it holds the voltage just before discharge and updates it with the output of the circuit 18, as shown by the two-dot chain line in the waveform (H). Therefore, a voltage corresponding to the engine speed can be obtained.

The voltage applied to the sample and hold circuit is applied to the lead angle setting section 5 in order to electrically set the lead angle value based on this value. The lead angle setting unit 5 outputs a waveform (voltage indicated by a broken line) according to a predetermined lead angle.

This W force voltage is compared with the voltage of the capacitor C, ie, the voltage shown by the solid line in the waveform (H), in the comparator 26, and a pulse signal shown in the waveform (Il) is output.

With this pulse signal, the monostable circuit n is triggered and the waveform (
A short pulse indicated by Jl is output at the set advance angle point.

The cylinder discrimination signal obtained from the aforementioned comparator sets a flip-flop. This flip-flop is reset by the output of the comparator 17, so the waveform (G
) is output.

Finally, a pulse (waveform (J
)) and the output (waveform (G)) of a flip-flop representing a predetermined cylinder, and an output signal (waveform (K)) for lighting the timing light is supplied to the output terminal OUT. Therefore, by turning on the timing light using this output signal and aligning it with the top dead center mark of the engine, you can see the advance angle.

In addition, the vibration frequency bandwidth is 100KHz to 400KHz.
This is because the high frequency components generated in the vicinity of the injector's operation are in a frequency band with a certain width with the peak frequency around 200 KHz.

In addition, the vibration frequency band that occurs in response to the opening timing of the injection valve includes vibration signals from sources other than the injection valve, but the vibration signals that correspond to the opening timing continue for a longer period of time than others. , it is easy to distinguish between these and improve the 8/N ratio of the vibration signal corresponding to the valve opening timing.

(Effects of the Invention) As explained above, according to the present invention, the frequency band of the output signal of the vibration sensor is 100 KHz to 400 KHz.
Since the injection start timing is detected by extracting and amplifying only the signal, dynamic injection timing detection can be easily and accurately performed. It is possible to provide an injection timing detection device for a diesel engine which can also be applied to the present invention. Furthermore, it is possible to provide an injection timing detection device for a diesel engine that can electrically set the advance angle based on the injection timing detected in this manner.

[Brief explanation of the drawing]

Fig. 1 is an example of mounting a vibration sensor, Fig. 2 is a diagram showing the principle of injection timing detection according to the present invention, Fig. 3 is a block diagram showing an embodiment of the present invention, and Fig. 4 is the operation of Fig. 3. FIG. 5 is a partially enlarged view of FIG. 4, and FIG. 6 is a diagram showing the frequency characteristics of the amplifier. 13; Vibration sensor 14: Amplifier 15; Bypass filter 16; Maximum value detection circuit 17: Comparator 18; Monostable circuit 19; Charge circuit addition; Sample hold circuit 21: Discharge circuit n; Delay circuit B; Maximum value detection circuit 24 : Comparator 5; Advance angle setting section 26; Comparator n; Monostable circuit foot; Flip-flop 4; AND circuit patent applicant
Nissan Motor Co., Ltd. Patent Application Agent Patent Attorney Megumi Yamamoto -12
11 #3 Me Appetizer 2-32
3- Figure 5 [F]

Claims (1)

[Claims] 1) A vibration detection sensor attached to the engine body or its fuel injection system, and a frequency band of 100 from the output of the sensor.
)G (Z to 400 KHz) and means for extracting and amplifying a vibration signal, and detecting the fuel injection timing from the amplitude of the vibration signal obtained by the amplification means. 2) A vibration detection sensor attached to the engine main body or its fuel injection system;
means for extracting and amplifying a KHz vibration signal; a valve-opening timing detecting means for detecting the opening timing of the injection valve from the amplitude of the vibration output signal of the amplifying means; and based on the vibration level of the output signal of the amplifying means, A cylinder determining means for determining a specific cylinder in which vibration is occurring due to the operation of the injection valve; and a signal corresponding to the engine speed according to the output signal of the valve opening timing detecting means; a time setting means for outputting a signal giving an angular point; and a time setting means for providing a signal to turn on a timing light at a time determined by the time setting means based on an output signal of the time setting means and a cylinder discrimination signal of the cylinder discrimination means. An engine injection timing detection device specially designed to include an output means and the following.