SU1413474A1 - Device for measuring the advance angle of fuel feed into diesel engine - Google Patents

Abstract

The invention makes it possible to increase the reliability of measurements by eliminating the possibility of a false triggering of the measurement circuit after the piston passes the top dead center and providing an unambiguous measurement pulse corresponding to the feed advance angle n, regardless of the presence of fuel injected fuel. The device contains sensors 1, 2 displacements of the nozzle needle and the top dead center, shapers 3.4 pulses, coincidence circuits 5, 19, triggers 6, 7, registers 8, 9, controlled generator 10, display unit 11, switch 12, a reset button 16, a zero bus 17, an inverter 18. A digital equivalent of the measured angle in the register is formed in those times that start at. start points of the fuel injection and end at the moments of the piston entering the top dead center, regardless of the nature of the fuel injection. 1 il. C (L

Description

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four; " four

The invention relates to the diagnosis of internal combustion engines and can be used to measure the fuel advance angle to a diesel engine.

The aim of the invention is to increase the reliability of measurement, which is achieved by eliminating the possibility of falsely triggering the measurement circuit after passing the upper dead point (TDC) by the piston and providing an unambiguous measurement pulse 5 with the corresponding advance advance angle, regardless of the presence of fuel injected.

The drawing shows a block diagram of a device for measuring fuel advance angle.

The device contains an injector 1 needle displacement sensor (not shown and TDC sensor 2, the corresponding first 3 and second 4 pulse shapers, the first circuit 5 matches the first 6 and second 7 triggers, the first 8 and second 9 registers, the control generator 10, the display unit 11, the switch 12 with the first 13 and second 14 fixed contacts and the movable contact 15, as well as the reset button 16 and the zero bus 17. At the same time, the injector needle movement sensor 1 Through the first pulse shaper 3 the pulse is connected to the single input of the first trigger 6 , to the zero mo th The TDC sensor 2 is connected through the second pulse shaper 4. The output of the first trigger 6 is connected to the first input of the first coincidence circuit 5, the second input of which is connected to the input of the second trigger 7, to the first fixed contact 13 of the switch 12 and the control output generator 10, and the output to the input of the first register 8, the output of which is connected to the display unit 11. The reset button 16 is connected between the setup inputs of the first 8 and second 9 registers and the zero bus 17 of the power supply. The second fixed contact 14 of the switch 12 is connected to the output of the second trigger 7, and the movable contact 15 to the input of the second register 9, the inverse output of which is connected to the input of the controlled generator 10.

The device is equipped with an inverter 1 and a second coincidence circuit 19, the first input of the second coincidence circuit 19 is connected to the output of the first pulse generator 3, the output to the single input of the first trigger 6, and the second input to the output of the inverter 18, whose input is connected to the zero input first trigger 6.

The device works as follows

In the case of measuring the fuel advance angle in a two-stroke diesel engine, the switch 12 is set to the closing position of the first fixed contact 13.

When the diesel nozzle is in operation, it injects fuel into the cylinder, so that the nozzle needle displacement sensor 1 generates an electrical impulse or several impulses (if there are injecting or fragmentation of the injection), which are converted into a rectangular impulse (or a set of impulses when fragmentation of the injection) of the normalized amplitude (for example, equal to the level of logical logic) and duration equal to the duration of the fuel supply. At the same time, the front edge of the output pulse of the imaging unit 3 coincides with the moment of the start of the fuel supply, and the rear edge - with the moment of the end of the supply in this diesel cycle. Before the piston sets in TDC, the zero signal acts at the output of the second pulse shaper 4, and the output of the inverter 18 is a single signal, which is fed to the second input of the second coincidence circuit 19, whereby the signal from the first output; The first pulse shaper 3 passes to the single input of the first trigger 6, which is set to one under the action of the leading edge of the first pulse generated by the shaper 3. When the diesel piston enters TDC, the sensor 2 produces a pulse, which is converted by the second shaper 4 into a rectangular the pulse of the normalized amplitude (for example, equal to the level of the logical unit), the leading edge of which corresponds to the beginning of the signal of the BMT sensor 2. The duration of this pulse is chosen to be longer than the duration of the fuel supply in each diesel cycle in any mode. At the time when the leading edge of the output pulse of the second

the first trigger 6 is reset, and the signal at the second input of the second matching circuit 19 drops from a single level to zero and retains it for the duration of the pulse of the second driver 4. This causes the second matching circuit 19 to be locked for the duration of the pulse the entrance of the second shaper And,

Under the action of the pulses of the first .3 and second 4 drivers, the first trigger 6 passes from one state to another and with each turn of the shaft of a two-stroke diesel engine produces one rectangular pulse of normalized amplitude and duration equal to the time interval from the start of injection to the time of the piston TDC, i.e. timing advance fuel. This pulse arrives at the first input of the first coincidence circuit 5, unlocking it.

The fuel advance angle measurement cycle starts from the moment the button 16 is pressed, as a result of which the first 8 and second 9 registers are reset to the zero state. In this case, at the inverse output of the second register 9, a single signal appears, which arrives at the control input of the controlled oscillator 10 pulses, and the display of the display unit-11 flashes zeros. From this moment, the controlled oscillator 10 generates pulses that go to the input of the second register 9 through the switch 12 and are not smooth, and to the input of the first register 8 are received only when the first coincidence circuit 5 is opened, i.e. if there is a single signal at the input of the first trigger 6. The measurement cycle continues until the first 8 and second 9 registers record codes. As soon as the number N., equal to the capacity of this register, is recorded in advance in the second register 9, at its inverse output, instead of a single signal, a zero signal is set and the generation of pulses by the controlled generator 10 is stopped. The measurement cycle ends.

During the measurement cycle, the first register 8 records the number N, whose value in the binary number system is displayed on the display panel 11. For the time period t3,

1A13D744

during which the indicated numbers are recorded, the diesel engine crankshaft performs the number of revolutions

m tj- F,

where F is the cyclic rotational speed

shaft.

0 In this case, the numbers N and N can be represented by the expressions:

N, N,

where t. - the duration of the output pulse of the first trigger 6,

fj is the frequency of the pulses of the controlled generator 1P, and the ratio of the numbers is as follows

NI F Wt4 S

N

mf,

wT

2lf

where fJ is the angular velocity of the shaft is di- zel,

T is the period of rotation of the shaft of a diesel engine,. - shaft rotation angle in one

turnover,

0 is the advance angle of the injection of a fuel tank.

The value of t is the fuel injection advance time, and (Ot is the advance angle.

From the last expression, we obtain a formula for calculating the advance angle of a two-stroke diesel fuel injection:

40

- "Nt g -1, -, 360N, g, 1G L - (1)

Given N 360 10 and choosing any integer values of K, the fuel injection advance angle is obtained from the readings of the display unit 11 by moving the comma to K of the characters to the left. To repeat the measurements, press button 16.

In the case of measuring the fuel advance angle on a four-stroke diesel engine, the switch 12 is set to the closing position of the second stationary contact 14. As in a four-stroke diesel engine

When the fuel is fed into the cylinder once every two revolutions of the crankshaft, the pulses arrive at the single input of the first trigger 6 with a frequency twice as low as the frequency of rotation of this shaft and equal to 0.5F. The pulse frequency at the zero input of the first trigger 6 coincides with the shaft rotation frequency and remains equal to F. Therefore, at the output of the first trigger 6, every two revolutions of the shaft, one pulse or a burst of pulses appears (in the presence of sub explosions or crushing of the pulse injection), At the output of the second driver A pulses are generated in each revolution of the shaft. When passing through the inverter 18, the pulse from the TDC sensor 2 locks the second coincidence circuit for its duration and prevents the first trigger 6 from being set to one state. Therefore, at each diesel cycle, the first trigger 6 cocks with one time. Therefore, the duration of the output pulse of the first trigger 6 is the fuel injection advance time.

The measurement cycle starts by pressing button 16, as a result of which registers 8 and 9 are reset, and zeroes are displayed on the digital display of the display unit 11. After resetting the second register 9, at its inverse output, a single potential appears at the control input of the controlled generator 10 and causes the formation of rectangular pulses that go to the second input of the first coincidence circuit 5 and to the counting input of the second trigger 7 as in the case under consideration, the pulse to the input of the second register 9 comes from the output of trigger 7, then the code is written to this register with a frequency twice as low as the recording frequency in the first register 8, when writing to the second register 9 A N signal equal to the capacitance of this register sets a zero signal at its inverse output, which causes the generation of pulses controlled by the generator 10 to stop and the measurement cycle ends. During the recording cycle tj, the first register B records the number N, the value of which is the decimal number system is indicated by the display unit 11.

Since in the considered case the recording in the second register occurs with a frequency of 0.5fj, the recording time of the number N, t, e, the measurement cycle, is determined by the expression

tj N / 0,5f ,, 2N / f,, (2)

and the crankshaft makes the number of revolutions

m tj-F 2NF / fg,

(3)

Since one fuel injection takes place over two turns of the shaft, the code in the first register 8 at the end of the measurement cycle is determined by outputting

 I t, f, NFt

 - T 2

Nt n

The numerator is the fuel injection advance angle, the value of which is determined as follows:

360N,

,, 2, Ш, г п JbUN, г - f, iN i. N

From a comparison of expressions (1) and (4) it can be seen that the formulas for calculating the injection advance angle in diagnosing two-stroke and four-stroke diesel engines are the same. By asking N 360-10 and choosing any integers K, the fuel injection advance angle is obtained from the indications of the display unit 11 of the display by moving the comma to K of the signs to the left. To repeat the measurement, press the reset button 16.

From the moment the piston enters TDC, the single input of the first trigger 6 is blocked for a length of time longer than the full fuel cycle, due to which the transition of the first trigger 6 from the zero state to one even in the presence of injection or splitting of the injection is impossible and the number in the first Register 8 between the cycles of fuel in the adjacent revolutions of the shaft of a diesel engine is excluded. This recording is made only at the time intervals from the moment of the start of injection to the time of entry of the rear axle at TDC, which correspond to the advance angle of the fuel injection. This increases the accuracy of the measurement result.

Thus, the proposed device provides higher accuracy of the measurement result.

Since the digital equivalent of the measured angle in the register is formed during those time periods that begin at the moments of the beginning of the fuel injection and end at the moments of the piston approach at the top dead center, regardless of the fuel injection pattern.

Claims (1)

Invention Formula A device for measuring the fuel advance angle to a diesel engine, comprising a nozzle needle movement sensor and a top dead point sensor, corresponding first and second pulse drivers, first coincidence circuit, first and second triggers, first and second registers, control generator, display unit , a switch and a button, the injector needle displacement sensor being connected through the first pulse shaper to the single input of the first trigger, to the zero input of which through the second connecting pulse shaper not top dead center sensor, first trigger output U134748 connected to the first input of the first circuit five 0 five We match, the second input of which is connected to the input of the second trigger, with the first fixed contact of the switch and the output of the controlled generator, and the output with the input of the first register, whose output is connected to the display unit, the reset button is connected between the setup inputs of the first and the second register and the zero bus power source, the second fixed contact of the switch is connected to the output of the second trigger, and the movable contact to the input of the second register, the inverse output of which is connected to the input of the controlled generator torus, so that, in order to increase the measurement accuracy, the device is equipped with an inverter and a second coincidence circuit, the first input of the second coincidence circuit is connected to the output of the first pulse generator, the output - to the single input the first trigger and the second input to the output of the inverter, the input of which is connected to the HJT-left input of the first trigger.