JPH0117649Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a fuel injection timing detection device, and more specifically, the present invention is designed to accurately and stably detect the fuel injection timing (advance angle) in a fuel injection pump for an internal combustion engine. The present invention relates to a fuel injection timing detection device.

For example, a fuel injection timing detection device conventionally used in an electronically controlled internal combustion engine includes a top dead center signal generator that generates a top dead center signal consisting of a pulse indicating the top dead center timing of the engine piston, and a top dead center signal generator that generates a top dead center signal consisting of a pulse indicating the top dead center timing of the engine piston. an injection timing signal generator that generates an injection timing signal consisting of pulses related to the fuel injection start timing of the pump, and measuring the phase difference of each signal obtained by these signal generators;
It is configured to detect the injection advance angle, that is, the injection timing (see Japanese Patent Laid-Open No. 75961/1983).

The injection timing signal generator used in this type of conventional device includes a timing plate fixed to the driven shaft of the fuel injection pump and an electromagnetic pickup coil. When it rotates with the
1 formed on the outer periphery of the timing plate.
One or more cogs sequentially approach and leave the electromagnetic pickup coil, thereby outputting an injection timing signal. The phase difference between this injection timing signal and the top dead center signal changes depending on the injection timing set in the injection pump, so the phase adjustment when installing the timing plate on the driven shaft is Not particularly needed.

By the way, when the actual temporal change in the injection advance angle θ is measured using the injection amount Q as a parameter, the characteristics shown in FIG. 4 are obtained. That is, the instantaneous value of the injection advance angle θ is accompanied by periodic fluctuations, and when the injection amount Q increases from Q ₁ to Q ₂ , the entire characteristic curve shifts downward, but ta, tb It can be seen that the fluctuations at each injection start point indicated by , tc, ... are the smallest.

However, if the phase between the timing plate and the driven shaft is not adjusted, the value of the detected injection timing data will not be stable. A phenomenon in which the adjustment of injection timing becomes unstable frequently occurs.

SUMMARY OF THE INVENTION Therefore, it is an object of the present invention to provide a fuel injection timing detection device that eliminates the above-mentioned drawbacks of the prior art and allows stable detection of injection timing.

The characteristics of the fuel injection timing detection device according to the present invention are as follows:
first means for generating a first pulse train signal comprising pulses indicative of predetermined reference timing of the internal combustion engine;
a second means for generating a second pulse train signal comprising pulses related to the fuel injection timing of the fuel injection pump that injects fuel into the internal combustion engine; In the fuel injection timing detection device, the second means is adapted to output a pulse at the static injection start timing of the fuel injection pump. .

Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

FIG. 1 shows an embodiment of a fuel injection timing detection device according to the present invention. This fuel injection timing detection device 1 is a device for detecting the fuel injection timing (advance angle) in a fuel injection pump for injecting and supplying fuel to a diesel engine 2, and is a device for detecting the fuel injection timing (advance angle) in a fuel injection pump for injecting and supplying fuel to a diesel engine 2. A top dead center sensor 4 that outputs a signal indicating timing is attached to the crankshaft 5 of the diesel engine 2. The top dead center sensor 4 is a pulser 6 fixed to the crankshaft 5.
This is a well-known sensor consisting of an electromagnetic pickup coil 7, and an electromagnetic pickup coil 7.
Pulse P ₁ every time the piston reaches top dead center
is output, and the pulse train signal consisting of these pulses is waveform-shaped by the waveform shaping circuit 8, as shown in Fig. 2a.
It is output as the top dead center signal _S1 shown in .

In this embodiment, the diesel engine 2 is a four-stroke, eight-cylinder engine, and four cogs are provided on the outer circumference of the pulsar 6 at 90° intervals. Therefore, the pulse constituting the top dead center signal S ₁ is output every time the crankshaft 5 rotates 90 degrees, and the top dead center signal S ₁
is input to the arithmetic circuit 9 as a signal indicating the reference timing of the device 1. In addition, top dead center signal S ₁
In , each rising point indicates the top dead center timing.

On the other hand, a driven shaft 1 of a fuel injection pump (not shown)
A timer 3 is provided between the diesel engine 0 and the diesel engine 2, and an injection timing sensor 11 is provided on the driven shaft 10. The injection timing sensor 11 includes a timing plate 12 fixed to the driven shaft 10 and an electromagnetic pickup coil 13 disposed near the timing plate 12.

In the illustrated embodiment, the timing plate 12 has eight cogs 12a to 12h formed on its outer periphery at 45° intervals, as shown in FIG.
As a result, when the driven shaft 10 rotates in accordance with the rotation of the crankshaft 5, the timing plate 12
A pulse P ₂ indicating the injection start timing is output every 45° rotation, and a pulse train signal consisting of these pulses is waveform-shaped in the waveform shaping circuit 14 to form the injection timing signal S ₂ shown in FIG. 2b.
is output as Note that each rise timing of the injection timing signal _S2 indicates the injection start timing in any cylinder.

The timing plate ₁₂ is arranged so that each cog faces the electromagnetic pickup coil 13 at the static injection start timing of the fuel injection pump so that advance angle value information with little variation can be obtained by this injection timing signal S2. , driven shaft 1
It is fixed at 0.

The injection timing signal _S2 is input to the calculation circuit 9, and the fuel injection timing (advance angle) at each time is calculated from the phase difference with the top dead center signal _S1 .

The calculations in the calculation circuit 9 will be explained with reference to FIGS. 2a and 2b. First, one of the pulses constituting the injection timing signal _S2 and the corresponding top dead center signal _S1 will be explained. From each rising timing time t ₁ , t ₂ of the pulse, both signals S ₁ ,
The phase difference θ of S ₂ is detected, and then the time T of one cycle of the top dead center signal S ₁ is detected from the difference between times t ₂ and t ₃ . Next, the injection advance angle is calculated based on these detection results θ and T. This calculation period is C, and the calculation of the injection advance angle described above ends at time _t4 , and the next calculation cycle begins at the rising timing of signal _S2 at time _t5 . In the above, one calculation cycle corresponds to a rotation angle of 135 degrees of the timing plate 12, but the length of one calculation cycle changes depending on the engine speed at that time. However, in any case, each pulse of the injection timing signal _S2 , which should be compared with the rising timing of each pulse of the top dead center signal _S1 , is output at the static injection start timing of the fuel injection pump. .

Therefore, when the fuel injection pump is at a static injection start timing and the timing plate 12 is fixed to the driven shaft 10 with each cog in a phase relationship corresponding to the electromagnetic pickup coil 13, the instantaneous advance value will change depending on the engine rotation. However, the advance angle information provided by the injection timing signal _S2 , which is composed of pulses output at the above-mentioned detection timing, is not affected by fluctuations due to engine rotation, and when the injection amount changes. However, the effect on the injection advance value is the smallest.

Therefore, the calculation result of the advance angle value obtained in the calculation circuit 9 is stable with the least influence of rotational speed, injection amount, etc., and there is little variation in data, and this calculation result allows stable advance angle control. can be done.

In the above embodiment, the number of cogs formed on the timing plate is made to match the number of cylinders, but the number of cogs does not necessarily have to be the same as the number of cylinders, and can be any number.

Furthermore, the present invention can be similarly applied to any fuel injection pump regardless of its type or number of cylinders.

According to the present invention, as described above, at least one cog formed on the timing plate faces the electromagnetic pickup coil at the static injection start timing of the fuel injection pump and outputs a required detection pulse. Since the detection pulse is output at the static injection start timing of at least one of the fuel injection pumps, irregular variations in the injection timing calculation results do not occur, and the rotational speed and injection amount are The influence of changes on the detection results is minimized, and stable detection can be performed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a fuel injection timing detection device according to the present invention, FIGS. 2a and 2b are signal waveform diagrams showing signal waveforms of each part of the device shown in FIG. 1, and FIG. 3 1 is a front view of the timing plate of the apparatus shown in FIG. 1, and FIG. 4 is a characteristic diagram showing temporal changes in injection advance angle using injection amount as a parameter. 1... Fuel injection timing detection device, 2... Diesel engine, 3... Timer, 4... Top dead center sensor, 5
... Crankshaft, 9 ... Arithmetic circuit, 10 ... Driven shaft, 11 ... Injection timing sensor, 12 ...
Timing plate, 12a to 12h...cog, 13...electromagnetic pick-up coil, _S1 ...top dead center signal, _S2 ...injection timing signal.

Claims (1)

[Claims for Utility Model Registration] 1. A first means for generating a first pulse train signal consisting of a first pulse indicating a predetermined reference operation timing of the internal combustion engine, and a fuel injection pump for injecting fuel into the internal combustion engine. a second means for generating a second pulse train signal comprising a second pulse related to the injection start timing; and a calculating means for calculating the fuel injection timing based on a phase difference between the first pulse train signal and the second pulse train signal. In the fuel injection timing detection device comprising:
A fuel injection timing detection device, wherein the means outputs the second pulse at a static injection start timing of the fuel injection pump. 2. The second means includes a timing plate fixed to the driven shaft of the fuel injection pump and provided with at least one cog on the outer periphery, and the cog sequentially approaches as the timing plate rotates;
an electromagnetic pickup coil disposed close to the timing plate so as to be separated from each other;
The fuel injection timing detection device according to claim 1, wherein the cog is set to face the electromagnetic pickup coil at the static injection start timing of the fuel injection pump.