JPS5815620B2 - Diesel engine injection start detection method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for detecting the start of injection in a diesel engine.

Conventionally, there have been methods and devices for detecting the rotational speed of a diesel engine using a fuel injection pump by mounting a pickup made of a piezoelectric element on a high-pressure pipe between the pump and the injection nozzle. There was no method or device for detecting the injection start timing of the engine.

This is because even if a piezoelectric element is mounted on a high-pressure pipe as described above and the pressure changes occurring in the pipe are extracted as an electrical signal, the electrical signal component corresponding to the injection start time is weak and contains a lot of noise. This is because it is difficult to accurately isolate only the injection start timing component because it is included in the electrical signal.

SUMMARY OF THE INVENTION An object of the present invention is to overcome the above-mentioned difficulties and to provide a system capable of accurately detecting the injection start timing.

An example of implementing the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a detection device according to the present invention,
FIG. 2 shows each waveform diagram of the electrical signals on each path AV shown in FIG. 1, and the present invention will be sequentially explained according to the first diagram.

(1) First, as shown in FIG. 1, a diesel engine E whose injection start timing should be detected.

A main pickup 1 and a sub-pickup 2 made of piezoelectric elements such as titanium sambarium are attached to the injection system, for example, a pressure vibrator.

That is, it consists of four cylinders e1 to e4, el, e3.
e4. In the case of a diesel engine in which each cylinder repeats one cycle of compression-injection-explosion in the order of e2, the main pickup 1 is placed on the pressure vibrator of el, which is the reference cylinder of the engine, and the main pickup 1 is placed immediately before the reference cylinder e1. 3 (2) Engine E where the sub-pickup 2 is mounted externally to the pressure vibrator of e2, which is the front stage cylinder that performs the cycle.
.

When the main and sub-pickups 1 and 2 operate, the main and sub-pickups 1 and 2 output electric signals exhibiting high-frequency voltage waveforms as shown in FIGS. 2A and 2B in response to pressure changes occurring in the pressure vibrators of both cylinders el and e2.

Here, in FIG. 2, A1 is an electric signal component (hereinafter referred to as the "start component") at the injection start time corresponding to a pressure change that occurs at the fuel injection start time in the pressure vibrator of the reference cylinder e.

), OK is an electrical signal component corresponding to a large pressure change that occurs in the pressure vibrator when the pipe line of the injection nozzle is closed immediately after the fuel injection (hereinafter referred to as the "road component").

) is the most prominent component of the electrical signal.

A22 A32A4 are electrical signal components (hereinafter referred to as noise components) corresponding to pressure changes that occur during the pressure vibration of the reference cylinder e1 due to the influence of pressure changes in the other cylinders e27e32e4.

). There are various other noise components in addition to these, but
They have been omitted.

Further, B2 is the beginning component corresponding to the pressure change of the front stage cylinder e2, B2 is the same end component, B1. B3. B4 is for each cylinder el, e3. This is the noise component of e4.

Therefore, in the present invention, the aim is to secure AI (starting component), which is between B10 and A'1,
Moreover, the following operation is performed by paying attention to the fact that the point is close to X.

The above output signal of main pickup 1 has a starting component A1.
and two filters 3 and 4 having different frequency bands that resonate with each frequency band of the end component A/1.
On the other hand, the output signals of the sub-pickup 2 are respectively input to filters 13 having the same frequency band as the filter 4.

(3)-1 The output signal A of the main pickup 1 which has passed through the filter 4 has a waveform such as C, in which the final component is emphasized.

After amplifying this waveform C with the high input impedance amplifier 5,
Noise is removed again using a filter 6, and amplified using a high input impedance amplifier 7 to obtain a waveform like D.

This waveform is passed through a detector 8 and a waveform shaper 9 to remove noise and convert the waveform to a low frequency to shape the waveform into a single waveform like E. Furthermore, the single pulse waveform E is processed by a one-shot multi-by-break 10. Convert to a square wave like F.

■Thus, this square wave F is the end component X of the reference cylinder e1.
1, the interval between F and F is equal to that of the cylinder e.
This corresponds to the period of one cycle of 1.

Therefore, this square wave F is inputted into the current circuit 11, and the cycle of the circuit 11 becomes equal to the period of the cylinder e1 in the diesel engine E.

The rotational speed is outputted, and the rotational speed is displayed on the tachometer 12 based on the output.

(4) On the other hand, the output signal of the sub-pickup 2 that has passed through the filter 13 becomes a waveform such as G with the final component emphasized, and then, as in (3)-I above, the output signal is passed through the high input impedance amplifier 14 and filtered. 15, an amplifier 16, a detector 17, a waveform shaper 18, and a one-shot multi-by-break 19, and convert the waveforms H and I into square waves such as J.

Since this square wave J corresponds to the end component B'2 of the preceding cylinder e2, the interval between J and J corresponds to the period of one cycle of the cylinder e2.

Therefore, even if this square wave J is used, the diesel engine E.

rotation speed can be obtained. (5)-I Above (3)
)-I and both the waveforms F and J obtained in (4) are input to the flip-flop 20, the flip-flop 20 becomes
It turns ON at the rising edge of the square wave J corresponding to the end component B'2 of the preceding cylinder e2, turns OFF at the rising edge corresponding to the end component A1 of the other reference cylinder e, and outputs a square wave like K.

This square wave includes the end component of the previous stage cylinder e2 to the reference cylinder e.
, and the beginning component A1 of the reference cylinder e1 must exist during this period.

■ This square wave K is integrated by the rotationally tuned integration circuit 21 to create a triangular wave like L, and then this triangular wave is input to the dividing circuit 22 to divide the square wave K into two, which generates a square wave like M. The square wave M is applied to one input terminal of the comparison controller 23.

(6)-I On the contrary, the output signal A of the reference cylinder e1 inputted to the other filter 3 becomes a waveform such as N in which the component A1 is initially emphasized in the filter 3.

This waveform N is converted into high input impedance amplifiers 24 and 25.
The waveform is amplified into a waveform such as O, and further detected and shaped into a waveform such as P by a detector 26 and a waveform shaper 27, and the shaped wave P is input to a comparator 28.

■ This comparator 28 compares the integral triangular wave input to the comparator 28 from the rotation-tuned integration circuit 21 of (5)-II with the shaped wave P of (2) above, and sets the level of P to the level of L. The control circuit 30 controls the degree of increase in the high input impedance amplifier 25 of the above I in order to maintain the same level as the above.

The purpose of this is to prevent waveforms in the waveforms of P, especially in the adjacent front signals, and to always obtain a stable waveform at a required predetermined level.

This control is called automatic feed b.
This is called ack gain control.

■ Shaped wave P adjusted by comparing with comparator 28
is further amplified into a waveform such as Q by an amplifier 29, and the waveform Q is applied to each input terminal of a flip-flop 31 and a gate circuit 32, respectively.

(7) Finally, the flip-flop 3 of (6)-1 above.
1 is connected to the square wave F obtained in (3)-1 above.
is applied.

The flip-flop 31 turns on at the rising edge of the first component A1 of the waveform Q, turns off at the falling edge of the square wave F, and outputs a square wave like R.

This square wave R corresponds to the interval between the starting component A1 and the ending component A1.

Next, this square wave R is transferred to the comparison controller 2 of (5)-II.
3 to the other input terminal.

18)-I The comparison controller 23 performs the above (5)-II
It is compared whether or not the force square waves R overlap in the two-divided square wave M, and only when they overlap, a constant voltage such as S is applied to the input terminal of the gate circuit 32 of (6)-1. Apply.

The fact that R overlaps within M means that the initial component A1 of the waveform Q obtained in (6)-1 is between A/1 and the midpoint between B10 and Xl, that is, This means that it exists near the end component A'1 of the reference cylinder.

(2) Next, the gate circuit 32 outputs a trigger wave such as T when the voltage wave S is applied and the pulse of the waveform Q of (6)-I is input.

That is, this gate circuit 32 operates when it is determined that the start component A1 of the reference cylinder e1 is immediately before the end component X1 of the reference cylinder e1 (by the comparison controller 23 in (2) above).

), the trigger signal corresponding to the starting component is output.

(2) Subsequently, the trigger wave T is input to the one-shot multi-by-break 33 to output a pulse wave such as U with a trigger signal corresponding to the starting component of the reference cylinder e1.

At this time, if the time constant of the pie break 33 is appropriately determined, the signal of the bird corresponding to the end component of the reference cylinder e1 following the start component can be removed.

Thus, the initial component of the reference cylinder e1 is this pulse signal U.
This means that other noise components and end components have been removed and accurately isolated.

(9)-1 The pulse signal waveform U is input to the delay circuit 34 so that it can be delayed freely.

(2) The pulse signal waveform U that has passed through the delay circuit 34 is converted into a negative potential waveform as shown in (2) by the inverting circuit 35, and the timing light 36 is made to blink with this waveform (2).

Thus, if the signal wave U is not delayed by the delay circuit 34, the blinking cycle of the timing light 36 is synchronized with (exactly coincides with) the cycle of the fuel injection start timing of the reference cylinder e1.

) and then repeat.

(2) However, normally, a mark m indicating the top dead center of the first stage cylinder el is engraved on the flywheel Ef of a diesel engine, facing the reference mark M.

Therefore, if the timing light 36 is made to blink without delay as in (①) above, the top dead center mark m will appear to have stopped because the blinking is synchronized with the injection start time, or
Since the two match exactly, the mark m is the reference mark M.
The vehicle does not meet this point and comes to a halt before that point.

■Next, when the above-mentioned pulse signal wave U is delayed by the delay circuit 34 and the blinking timing of the timing light 36 is delayed as a whole, the top dead center mark m gradually approaches the reference mark M, and a predetermined point is reached. Both marks m and rr (completely match in terms of delay).

(2) The degree of delay of the pulse signal wave U in the delay circuit 34 is taken out by the current circuit 37, and the value is displayed on the delay angle meter 38.

The value displayed on the make 38 indicates how many degrees before the top dead center of the reference cylinder e1 the injection start timing is.

As described above, according to the present invention, the fuel injection start timing of a diesel engine can be detected as an electrical signal.

Furthermore, since the influence of noise components such as pressure changes occurring immediately after fuel injection and pressure changes caused by other cylinders is completely removed, the detection is extremely accurate.

Furthermore, since it is detected as an electrical signal, subsequent processing, such as displaying the number of revolutions and displaying the position relative to top dead center using a delay angle meter, can be performed very easily.

[Brief explanation of the drawing]

The drawings show one example of carrying out the present invention; FIG. 1 is a block diagram of the apparatus of the present invention, and FIGS. In the above figure, each symbol indicates the following. 1: Main pickup, 2: Sub pickup, 3,
4, 13, 6, 15: Filter, 5, 7° 14.16,
24, 25, 29: High input impedance amplifier, 8,
17, 26: Detector, 9° 18.27: Waveform shaper, 1
0, 19, 33: One shot multi-bye break, 1
1, 37:' optical circuit, 12: rotation meter, 20, 31: flip-flop, 21: rotation-tuned integration circuit, 22:
Division circuit, 23: Comparison controller, 28: Comparator, 3
0: Control circuit, 32: Gate circuit, 34: Delay circuit, 3
5: Inverter, 36: Timing light, 38: Delay angle meter, Eo: Diesel engine, e1 to e4: Diesel engine cylinder, Ef: Flywheel.

Claims (1)

[Scope of Claims] 1 Select a reference cylinder in which the fuel injection start timing of a diesel engine is to be detected and a pre-stage cylinder whose cycle is repeated immediately before that cylinder, and generate a pressure vibration etc. that communicates with the fuel injection nozzle of the one cylinder. The pressure changes are simultaneously taken out as electrical signals for each separately, noting that the starting component A1 in the reference cylinder is between the ending component B2 in the preceding cylinder and the ending component A1 in the reference cylinder, and that A1 is close to A1. , the time interval between the two path components B'2 and A' is divided into two, and when the desired starting component A1 is included in the two-divided time interval that is closer to A1, the pulse electricity generated by the starting component A1 is generated. A method for detecting the start of injection in a diesel engine, characterized by outputting a signal. 2 Select a reference cylinder in which the timing of starting fuel injection in a diesel engine is to be detected and a pre-stage cylinder that repeats the cycle just before that cylinder, and electrically measure pressure changes occurring in a pressure pipe leading to the fuel injection nozzle of that one cylinder. A device that simultaneously extracts each component as a signal, a device that divides the time interval between the end component B2 in the preceding cylinder and the end component A1 in the reference cylinder into two, and a device that detects the injection start component A in the reference cylinder and detects this as the road component. An apparatus for detecting the start of injection for a diesel engine, comprising: a device for outputting an electric signal according to the injection start component A1 when the injection start component A1 is within a two-divided time interval that is closer to A1.