JPS5970878A - Measuring device for fuel injection timing of diesel engine - Google Patents

Abstract

PURPOSE:To simplify an injection timing measuring device and to reduce a manufacturing cost, by a method wherein a counted value at a time when a top dead center is detected is determined as a reference value, differences between the reference value and a value at a time when injection starts after detection and between the reference value and a value at a time when the top dead center is detected again are respectively computed to find a time between injection start and detection of the top dead center and the period of the top dead center. CONSTITUTION:A microcomputer 11 inputs to an I/O an injection start signal P1 outputted when fuel injection start is detected, a first cylinder top dead center signal P3 outputted when the top dead center of a first cylinder is detected, and a sixth cylinder top dead center signal P4 outputted when the top dead center of a sixth cylinder is detected. Thereafter, based on these input signals, the microcomputer 11 reads in a count value CN of a counter 12 serving as a counting means for counting a clock pulse CK of a specified period, and based on the count value CN, it computes a time between the top dead center and injection start and a time between the first top dead center and the sixth top dead center. This permis measurement of two types of times by means of a single counter, resulting in simplification of the device, and reduction of a cost.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection timing measuring device for measuring the fuel injection timing of a de-C-cell engine.

In general, in diesel engines, in order to accurately set the timing of fuel injection from the engine's fuel injection valve, it is important to accurately measure the fuel injection timing, especially under dynamic fuel injection conditions while the engine is running. .

Conventionally, there is a fuel injection timing measuring device as shown in FIG. 1, for example, which determines the fuel injection timing al11.

This device first sprays water while the engine is running! A vibration sensor detects the vibrations generated by the N butt or the injection pipe when fuel is injected, and this detection signal is processed to produce the result shown in Figure 2 (
The fuel injection start signal P1 as shown in Figure 2 (H )
Top dead center belief as shown in: P28? stomach,. □Tsu...
At time 'r3 in FIG. 2 when the injection start signal P is input, the reset 1 signal R1 is output to reset the counter 2 that up-runs the tarok pulse CK at a constant period.
Start counting at 1, and read the count value CA of counter 2 at 4 when the top dead center signal P2 is input, and calculate the count value CA at this time and the clock pulse GK.
The time t from the start of injection to the top dead center is measured from the period of .

When the counter 2 reaches the upper limit, the counter 2 outputs an interrupt request signal Q+ to the microcomputer 1, is automatically reset, and starts counting again, and the microcomputer 1 Limit Count 1 - Store value.

Furthermore, the microcomputer 1 outputs a reset signal R2 at time T+ (and T4) in FIG. 1- is started, and the count value CB is started from the counter B at time T2.
Interrupt request signal Q indicating that " has reached the second limit value CBo
When 2 is input, the upper limit count value CBo is memorized, and when the top dead center signal P2 is input again], the counter 3's curran i/value CB is read into ``4'', and the curran 1 - value CBI at this time is and the stored upper limit count value CBo, and calculate the time from top dead center to the next top dead center based on this added count value and the cycle of clock pulse CK (top dead center cycle)]
゛ is measured by R1.

Then, this microcomputer calculates the time from the start of injection to the second dead center measured four times in duplicate and the time from top dead center to top dead center ゛r, ±×36
Calculate the injection advance angle by calculating 0°.

In this way, in the conventional fuel injection timing measuring device,
In order to measure the time from the start of injection to the top dead center and the top dead center cycle, counters were required, respectively, which resulted in the inconvenience of complicating the entire device and increasing the cost.

The present invention has been made in view of the above two points, and an object thereof is to simplify the structure of the fuel injection timing measuring device for a diesel engine as described above, and to reduce costs.

Therefore, the fuel injection timing measuring device for a diesel engine according to the present invention uses the argument value at the time of top dead center detection of the counting means for counting clock pulses of a constant period as a reference value, and uses this reference value and the argument value at the time of top dead center detection as a reference value.Injection starts after the second dead center is detected. The difference between the argument values when detecting 1; and the reference value and the argument values when top dead center is detected again after second dead center is detected is calculated, and based on these calculation results, from the start of injection. '' The time to second dead center and the dead center cycle can be determined in -.

Embodiments of the present invention will be described below with reference to FIG. 3 and subsequent figures of the accompanying drawings.

FIG. 3 is a block diagram showing the main parts of a fuel injection timing measuring device for a six-cylinder diesel engine according to the present invention.

In the figure, a microcomputer (hereinafter not referred to as "microcomputer") 11 is composed of a CPU (central processing layer), a program memory (ROM), a data memory (RAM), an input/output device (I10), etc. The injection start signal PI output when the start of fuel injection is detected + the first cylinder top dead center signal P3 output when the dead center is detected in the - of the first cylinder, and the second dead center of the sixth cylinder is detected. The output sixth cylinder top dead center signal P4 is input to Ilo.

Based on these input signals, the microcomputer 11 reads the count value CN of the counter 12, which is a counting means for counting the tarock pulse GK of a constant period, and counts the count l- Based on the value CN, the time from the top dead center of the first cylinder to the start of injection, the time from the top dead center of the first cylinder to the top dead center of the sixth cylinder, etc. are calculated.

Note that the counter 12 is reset when a reset signal R is input from the controller 11, and the counter I-value C is reset.
When N reaches the upper limit, an interrupt request signal Q is output to the microcomputer 11, automatically reset to reset 1, and then reset to 1 again.
-, and on the other hand, every time the interrupt request signal Q is input, the microcomputer 11 starts the upper limit value CNo of the counter 12.
is added to a predetermined address in RAM (memory M) and stored.

Thus, in this embodiment, the microcomputer 11 constitutes the first calculation means and the second calculation means, the details of which will be described later.

Here, a circuit for outputting each input signal of the microcomputer 11 will be explained with reference to FIGS. 4 to 6.

First, in FIG. 4, the vibration sensor 14 is installed near the spill tube of the injection valve of the sixth cylinder, and generates a detection signal S in response to the vibration of the spill tube.

is output to the injection start detection circuit 15.

As shown in FIG. 5, this injection start detection circuit 15 amplifies the detection signal S1 of the vibration sensor 14 with an amplifier circuit 158, and passes it through a filter 15B to obtain a detection signal S2 (sixth (see figure (a)), half-wave rectifier circuit 1
The envelope output 82' is obtained by half-wave rectification in 5G, and the background noise of the detection signal S2 is averaged by the averaging circuit 15I) to obtain the slice level SL+ (Fig. 6 (a)
), the comparison circuit 15E compares the envelope output S2' of the detection signal S2 with the slice level St from the averaging circuit 15E, and the comparison circuit 15E determines the signal S2'.
≧SL.

When this occurs, an injection start signal P1 having a predetermined pulse width as shown in FIG. 6(b) is output.

Returning to FIG. 4, the second dead center sensor 16, although not shown, is a gap sensor that detects a top dead center mark provided on the outer periphery of the engine flywheel at a position corresponding to the top dead center of the first cylinder. When the top dead center mark is detected, that is, when the pistons of the first and sixth cylinders reach the second dead center, a detection signal S3 is output to the second dead center detection circuit 17.

This top dead center detection circuit 17 amplifies the detection signal S3 from the second dead center sensor 16 and outputs a top dead center signal P2 with waveform shaping.

The sixth cylinder top dead center detection circuit 18 is connected to the injection start detection circuit 15.
The injection start signal PI from the top dead center detection circuit 17 and the top dead center detection signal P2 from the top dead center detection circuit 17 are input, and the pulse width of the injection start signal P1 is widened as necessary. The logical product of the point signal P2 is taken to output the sixth cylinder top dead center signal P4.

In other words, with only the top dead center signal []2, the first and sixth cylinders
Since it is not possible to determine which cylinder, the detection signal S1 of the vibration sensor 14 attached to the sixth cylinder is logically ANDed with the injection start signal PL obtained by signal processing, and the second dead center of the sixth cylinder is determined. It is determined.

Then, this 6th cylinder north dead center signal P4, the signal passed through the inverter 1, and the 2nd dead center signal P2 from the top dead center detection circuit 17 are inputted to the AND circuit 20, AND is taken, and the 1st cylinder -I Obtain top dead center signal P3.

Note that the cylinder in which the second dead center is detected is the first cylinder. It is not limited to the sixth cylinder, but may be other cylinders.

In that case, the "1st dead center" of the two cylinders can be distinguished by attaching a vibration sensor to the cylinder that detects the top dead center.
This can be determined in the same manner as described above.

Next, the operation of the embodiment configured as a double series will be explained with reference to FIGS. 7 and 8.

FIG. 7 shows the counter 1 executed by the microcomputer 11 in FIG.
FIG. 2 is a diagram illustrating a processing flow diagram of count value No. 2;

In the same figure, S'rEPI, 2: Time 'I' in Figure 8
As shown in I, i''3+T4, when the 1st cylinder's second dead center signal P3+injection start signal p or the 6th cylinder's top dead center signal P4 is input manually, interrupts are prohibited and 5TEP3 and subsequent steps are executed.

S'rE P 3 to 5: Determines whether the input pulse is the 1st cylinder top dead center signal 1], ], and outputs the 1st cylinder top dead center signal P
If it is 3, read the value CN of counter 12 and set R, A.
After storing the counter upper limit value in the memory M of M, the memory M adds and stores the counter upper limit value. Clear.

Furthermore, the value of the memory M2 (described later) containing the value 1-)2 corresponding to the time to after the second dead center until the start of injection in the first cylinder is transferred to the memory M4 (described later), and the value of the first cylinder- After the second dead center is detected, the values in the memory M3 (described later) containing values 1 to IJ3 corresponding to the paralysis time T' for detecting the second dead center are transferred to the memory MS.

Then, cancel the interrupt and proceed to the next flow, and if the dead center signal is not P3 for the first cylinder, S T E P6
Proceed to.

Therefore, in FIG. 8, the counter 12's count 1--i direct CN1 at the time T1 when the first cylinder top dead center signal P3 is input is stored in the memory M1 of the microcomputer 11.

5TEI) 6, 7: Determine whether the input pulse is the injection start signal P, and if the input pulse is the injection start signal p, the counter 1
Read the value CN of 2 and set the upper limit of counter 12 to 1.
The memory Mo that stores the value cNo and the count value CN at the time of detecting the top dead center of the first cylinder are stored (STE Bi4)
Read the contents of memory M1, (CN-1-Mo M
+ ) to obtain the count value D2 of the counter 12 from the second dead center of the first cylinder to the start of injection, and after storing this count value D2 in the RAM memory M2, 5TEP8
If the injection start signal is not P1, continue to 5T.
Proceed to EP8.

Therefore, in FIG. 8, after adding the upper limit count value CNo stored in the memory MO at time T2 to the count value cN2 at time T3 when the injection start signal P1 was input,
The value obtained by subtracting the count value CN, which is the reference value stored in the multi-purpose memory M1, from the added value (CN2
) are stored in the memory M2 as numbers 1 to D2.

5TEP8,97 input pulse is the 6th cylinder top dead center signal P4
If it is the 6th cylinder top dead center signal P4, read the value CN of the counter 12 and select S T E P 7.
In the same manner as above, calculate (CN 10aoL) to obtain the count 1 shift 1]3 of the counter 12 from the top dead center of the first cylinder to the top dead center of the sixth cylinder, and store this count value D3 in the memory. M
3, the program proceeds to 5TEP5, and if the sixth cylinder top dead center signal P4 shows no number, the program directly proceeds to 5TEP5, cancels the interrupt, and executes the next flow.

Therefore, in FIG. 8, the sixth cylinder top dead center signal P4
is inputted, the count value CN3 of the counter 12 at "1"4 is set to the upper limit count value C stored in the memory MO.
After adding No., the value obtained by subtracting the count value CN, which is the reference value stored in the memory M1, from the added value
34-CNo CN1) is stored in memory M3 as callan h@I)3.

In this way, the memory M2 of the RAM of the microcomputer 11 is stored in the memory M2 of the RAM of the microcomputer 11 as shown in FIG. ) is stored in the memory M3 as shown in FIG. The time until detecting a point (-dead center cycle) i' k - equivalent value 1 - value 1) 3 are stored, respectively.

However, the time 1 from the start of injection to the second dead center of the 6th cylinder (see 8th cylinder) is calculated by the count value D2 and the force run l.
- the difference of the value 1) 3 and the period of the tarok pulse G K 101
1χ, (t = (D3-1.)2)・
1 missing), the top dead center period '1' is determined by the count value D3 and the period tχ of the tarok pulse 0 ('L'
= I) 3・shiX).

By doing this, "C" can be found.

In other words, calculate the injection advance angle □ x 360° and calculate 3 demand.

In this way, using the value of counter 1-2 to run 1 when the top dead center of the first cylinder is detected as the reference value, what is the difference between the count value and the reference value when the start of injection is detected after the first dead center of the first cylinder is detected? By determining the time tQ from the top dead center of the first cylinder to the start of injection 11, when the top dead center detection image detects the I dead center again, -) the first dead center of the 1st cylinder A is detected. By calculating the difference between the count value and the count value when the top dead point of the rear sixth cylinder is detected, the top dead center cycle can be calculated. -1-,
Two types of time measurement can be performed: the time to dead center Ilt and the second dead center period 'r.

FIG. 10 is a block diagram similar to FIG. 3 showing another embodiment of the second invention.

In this embodiment, the microcomputer 21 sends the injection start signal P1 + the first cylinder - to the dead center signal P3 + the sixth cylinder - [
- In addition to the dead center signal P4 - the injection end signal that is output when the end of C1 injection is detected! 15 is entered.

Note that the injection end is determined by a circuit configuration similar to that of the injection start detection circuit 15 shown in FIG. This can be detected by setting the level to a value higher than the level of the detection signal S2.

Next, the operation of this practical example will be explained with reference to FIGS. 11 and 12.

FIG. 11 is a diagram showing the processing flow of the value to call 1 of the counter 12 executed by the microcomputer 21 of FIG. 10.

In the same figure, 5TEPII to 5TEP19 are the 7th
Figure (7) STE P1- STE P9,
l- Since the process is exactly the same, the explanation thereof will be omitted.

Therefore, to explain about STE P 20.21, it is determined whether the input pulse is the injection end signal P5 or not, and if it is the injection end signal P5, the value CN of the counter 12 is read and the memory MO is and the contents of memory M, calculate (CN+Mo M+) to obtain the count value D4 of the counter 12 from the top dead center of the first cylinder to the end of injection, and transfer the value 1-)4 to the count value 1 in the memory M6. If the injection end signal I) is not 5, the process directly proceeds to 5TEP15.

Therefore, in FIG. 12, the count value CN4 of the counter 12 at time T5 when the injection end signal P5 is input.
,Memory M. After adding the upper limit count value CNO stored in the memory M1, the count value CN stored in the memory M1 is subtracted from the added value (CN4 +CNOCN+
) is stored in the memory M6 as a count value D4.

In this way, the value D4 to Callan 1 corresponding to time t1 in FIG. 12 stored in memory M6 and the time t in FIG. 12 stored in memory M2. The fuel injection time t2 can also be obtained by calculating the difference with the count value D2 corresponding to .

Note that the other functions are the same as those of the previous embodiment, so the explanation thereof will be omitted.

In this way, even if you set the injection time in addition to the top dead center cycle and the time from the start of injection to top dead center, you only need one counter, and the injection time is 11 if! There is no need to provide a counter for l.

Incidentally, in each of the above embodiments, an example has been described in which the M1 number means is an up counter, but it goes without saying that it may be a down counter.

Further, in each of the above embodiments, an example has been described in which two types of signals are input as the top dead center signal, but one type of signal may be used.

Further, in the second example, a six-cylinder diesel engine has been described, but it goes without saying that the present invention can be similarly applied to a fuel injection timing measuring device for a diesel engine with a different number of cylinders.

As described above, according to the present invention, the structure of the fuel injection timing measuring device for a diesel engine is simplified, and the cost is reduced.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of main parts showing an example of a conventional fuel injection timing measurement device for a diesel engine, Fig. 2 is a timing chart 1 diagram for explaining the same, and Fig. 3 is a diagram showing a timing chart 1 of a conventional diesel engine fuel injection timing measuring device. 4 is a block diagram showing an example of a fuel injection timing measuring device for a six-cylinder diesel engine; FIG. 4 is a block diagram showing an example of a circuit configuration for generating an input signal to the microcomputer 11 shown in FIG. 6; 5 is a block diagram showing an example of the injection start detection circuit shown in FIG. 4, FIG. 6 is a signal waveform diagram for explaining the same, and FIG. 7 shows a counter 12 executed by the microcomputer 11 shown in FIG. FIG. 8 is a timing diagram for explaining FIG. 7; FIG. 9 is a flowchart showing the injection advance angle calculation process executed by the microcomputer in FIG. 3. 10 is a block diagram of the main part similar to FIG. 3 showing another embodiment of the present invention, and FIG. 11 is a block diagram of the counter 12 executed by the microcomputer 21 of FIG. Flowchart showing the processing flow. FIG. 12 is a timing chart for explaining FIG. 11. 11.21... Microcomputer (first and second calculating means) 12... Counter (counting means) Fig. 5 1 ゜. , 2, “ Figure 7 next frame - = \ Figure 8 Figure 9 next east - □ 17 □ □ □ J - □ □ □ □ 10th ty: + 1

Claims (1)

[Claims] 1. Start of fuel injection and piston of diesel engine,
(In a fuel injection timing measurement device that detects the second dead center and measures the fuel injection timing based on each detection result, it includes an HI number means that continuously records clock pulses of a constant period, and a second dead center as described above. A first operation for calculating the difference between the reference value and the count value of the recording means when the start of injection is detected after the detection of the second dead center, with the count value of the recording means when the second dead center is detected as a reference value. and a second calculating means for calculating the difference between the reference value and the count value of the counting means when the top dead center is detected again after the second dead center is detected. fuel injection timing measuring device.