SU1173231A1 - Device for measuring angle of advance of fuel injection into combustion engine - Google Patents

Abstract

1. DEVICE FOR MEASUREMENT OF THE ANGLE OF LEADING INJECTION OF FUEL INTO THE INTERNAL COMBUSTION ENGINE; containing a pressure sensor, an amplifier, a filter, a reference signal source, a first comparator, an upper dead center mark sensor and a measuring unit, wherein the pressure sensor is sequentially connected through an amplifier and a filter to a reference signal source to which a first comparator connected to an amplifier output, and an upper dead center sensor connected to a measuring unit, characterized in that, in order to improve accuracy by improving noise immunity, a second computer is added to it the aor, the time interval shaper, the pulse shaper and the time selector, and the reference signal source is provided with a second output, the first input of the second comparator is connected to the amplifier output, the second input to the second output of the reference signal source, and the output to the first control input of the time selector and the first input of the time interval shaper, the second input of which is connected to the output of the first comparator, and the output is connected through the pulse shaper to the time selector input, the output of which It is one with the second time of the measuring unit, and the second control input is with the output of the top dead center mark sensor. (О 2. The device according to claim 1, (()) is that the time selector contains a reference delay element, a reference time generator, a key, a pulse driver and a frequency converter, the element of the reference lock, a reference time generator and the key is connected WITH in series, the first and second IsD control inputs of the reference delay delay element CO and the reference time driver are connected respectively to the output of the pulse driver and to the output of the frequency converter, the pulse driver connected to the input of the reference delay element and the input of the frequency converter form the first and second control inputs of the time selector, respectively, and the input and output of the key, respectively, the input and output of the time selector.

Description

The invention relates to the field of instrumentation and can be used in electronic devices designed to study, test and diagnose diesel 5 internal combustion engines.

The purpose of the invention is to improve the accuracy by increasing the noise immunity of the device.

FIG. Figure 1 shows the structure of the device; in fig. 2 - time diagram of his work.

The device contains series-connected pressure sensor 1 in series, amplifier 2, filter 3 and reference source 4, a comparator 5, the first input of which is connected to the output of the amplifier .2, and the second input to the first output of the source 20 4, sensor 6 marks of the top dead center, connected to the first input of the measuring unit 7.

A second comparator 8, shaper 9 time intervals of 25 intervals, shaper 0 pulses, time selector II, and source 4 are provided with a second output are entered into the device. The first input of the comparator 8 is connected to the amplifier output, the second input is connected to the second output of source 4, and the output is connected to the first control input of the time selector 11 and the first input of the driver 9. The second input of the last is connected. with the output of the comparator 5, and the Q output is connected through the shaper 10 with the output of the temporary selector 11, the output of which is connected to the second input of the measuring unit, and the second

control input - with DATCHI output

ka 6.

The time selector 11 contains a series-connected element

12 support delay driver 45

13 retainer time interval and the key 14, the driver 15 pulses and the Converter 16 frequency. The first and second control inputs of the element 12 and the former 13 are connected respectively with the output of the former 5 and the output of the transducer 16. The former of the former 15 connected to the input of the element 12, and the input of the transducer 16 form the first and second control inputs 55, respectively and the input and output of the key, respectively, the input and output of the temporary selector 11.

The sensor I is installed on the high pressure pipeline of the internal combustion engine and contains one or several piezoelectric elements that are sensitive to the deformation of the external diameter of the pipeline and located on the sensor housing I and connected to the surface of the pipeline through the transmitting elements. When a pipeline is deformed, for example, at the time of fuel injection, the sensor's sensing element generates an electrical signal proportional to the deformation of the outer diameter of the pipeline and, consequently, the pressure inside it.

 The amplifier 2 amplifies and converts the electrical signal of the sensor 1 to a voltage and can be made in the form of a charge amplifier (the construction schemes are known).

As an operational amplifier can be used, for example, a chip K544UD2.

Filter 3 is made in the form of a low-pass filter with a cut-off frequency that provides suppression of the high-frequency components of signal 1, resulting from the impact of vibro-acoustic signals from collisions in the kinematic pairs of the engine in the nozzle, which determine the parasitic deformation of the pipeline. Filter 3 can be made in the form of an active filter.

As an operational amplifier filter can be used, for example, chip K140UD8.

Source 4 is designed as an amplitude rectifier, which converts the amplitude of the input signal into a constant voltage, and a partitioned output divider. The outputs of the first and second sections of the divider form the first and second outputs of source 4, respectively, and ensure the division of the output signal of the amplitude rectifier with division factors equal to 0.7-0 and 0.1-0.2, respectively. Circuit diagrams for amplitude rectifiers are known.

As an operational amplifier, K140 series chips can be used.

Comparator 5 is an analog voltage circuit comparator (construction known) and can be implemented in a chip circuit, for example, on a microcircuit of the type 521 SAZ. The sensor 6 generates one pulse per crankshaft revolution at the moment of reaching the top dead center (lm.t.) porish of the cylinder under control and can be made into the form of an induction speed converter installed against the hole in the flywheel and connected to the output of the rammer of a battling pulse at the moment of changing the polarity of the signal of an inductive converter. Measuring unit 7 measures the phase shift between pulses arriving at its inputs and can be performed as a digital phase meter with a frequency multiplier or digital meter of the ratio of temporary integrals. For example, a time interval ratio meter may be used. The design of comparator 8 is similar to that of comparator 5. Shaper 9 can be made as a front-triggered D trigger, input D of which is connected to a signal source with level 1. Clock input C of the trigger and its control input R form the first and second inputs of the imager 9, respectively Trigger Q output - Shaper 9 output, - A trigger can be implemented, for example, on a K155TM2 chip. The shaper 10 operates on a slice of the input pulse, forms a short pulse of a fixed duration, and can be implemented on a K155AG1 chip. Element 12 generates a pulse delayed relative to the input by a fixed reference value of the rotation angle of the crankshaft j 4 4 10 10 where / (the shortest possible time for the pressure signal to rise when fuel is injected between the levels generated by source 4. Element 12 is made on the basis of a controlled waiting multivibrator, the time of the driver circuit of which is powered by a control voltage and a pulse shaper connected to its output. The magnitude of the delay is inversely proportional to the control voltage. The op can be made on the basis of an integrated timer, including a microcircuit version of a KR1006VI microcircuit. The design of the element 12 is similar to that of the imaging device 10. The imaging unit 13 generates an pulse, the duration of which corresponds to a fixed reference UHF 5- W - kf fnax m "n where V, is the maximum possible duration of the rise of the pressure signal when fuel is injected between the levels formed by source 4. The design of the former 13 is similar to the waiting multivibrator element coagulant 12. The key 14 is a logic element 11. The structure 15 is similar to the shaper 10. The shaper converter. 16 produces a constant voltage proportional to the frequency of the pulses. The converter can be made according to a well-known scheme consisting of an analog switch, switching a low-frequency signal from the output of a voltage source or a zero potential, respectively, during the pulse duration and pause of the waiting multivibrator triggered by the input frequency pulses. An analog switch can be made on a K590KN2 type microcircuit, a reference voltage source based on an K140 series opamp and a 818 Zener diode. A standby multivibrator can be made on a K155PG1 type microcircuit, the low-pass filter design is similar to the filter 3 design. the frequency of the following input pulses. The principle of operation of the proposed device is to form a pulse when the pressure of the fuel injection signal reaches a level equal to the amplitude value of the pressure signal and measure the advance angle of the front of the moment of reaching the moment. controlled cylinder. The measurement is carried out if the moment of occurrence of the front of the generated pulse falls in a time window that is between the minimum and maximum V values of the crankshaft angles of rotation corresponding to the minimum and maximum rise times of the signal from sensor 1 when fuel is injected from a level equal to 10- 20%, to a level equal to 70-80% of the amplitude value of the pressure signal. Accordingly, the generated pulse is blocked, and the measurement does not occur if the rise time of the signal from sensor 1 is outside the specified range, which allows suppressing the high-frequency and low-frequency ones, causing parasitic deformation of the pipeline, and, consequently, increasing the noise immunity of the device. The device operates as follows. The signal from the output of the sensor, installed high pressure pipeline, is converted and amplified by amplifier 2 and the input of the filter 3 and the signal inputs of the comparators 5, 8. The filter 3 suppresses high-frequency noise superimposed on the signal of sensor 1 This allows the amplitude driver of source 4 to generate a constant voltage U proportional to the amplitude of the pressure signal during fuel injection. At the first and second outputs of source 4, respectively, the reference signals U and U of a constant voltage are proportional to the voltage U ,, and U, Ug U The reference signal Uj goes to the reference input of the comparator 5, the reference signal and the reference input of the comparator 8. Sensor 6 generates a pulse in the moment of reaching the i.e. piston controlled cylinder. The pulses from the output of sensor 6 are fed to the first input of the measuring unit 7 and to the second controlling the time selector 11. In the time selector 11, a signal is generated that sets the parameters of the time window in units of the angle of rotation of the shaft. . At the moment when the signal at the output of the amplifier 2 of the reference level Uu is exceeded, the comparator 8 triggers and generates a pulse, the duration of which is equal to the time it takes for the signal of this level. The pulse from the output of the comparator 8 is fed to the first input of the imaging unit 9 and to the first control input of the time selector 11. At the time of the formation of the front of this pulse, the force generator 9 is triggered and forms the output signal 1, which arrives at the input of the imaging unit 10. The same time, the time selector 11 and it forms a time window, the front and the slice of which are retransferring relative to this moment, respectively, to the angles of the numbers: „and.. „Gp 11 t rotation shaft. In the specified range of rotation angles of the time selection shaft, the torus 11 connects the output of the imaging unit 10 to the second input of the measuring unit 7. At the time of the signal output from the amplifier 2 of the Ug level 2, the comparator 5 is triggered and the output of the imager 9 produces the O signal. Thus, at the output of the imager 9, an impulse is formed, the duration of which is equal to the rise time of the signal from the level U to 1) 5, and corresponds to the rotation of the shaft during this period of time by n1 which is the angle of the signal according to the differential signal forming the output of the imager 9 , a short impulse is triggered, which arrives at the input of the time selector 11. The front of this impulse lags behind the timing of the time selector by the time selector shaft rotation. If. „„ S mo.x, then the impulse from the output of the imager) 0 passes through the time selector 11 and goes to the second input of the measuring unit 7, launched it. After a certain angle ug of shaft rotation, the first input of the measuring unit 7 receives a signal from the output of sensor 6. The measuring unit 7 detects the shift between the signals arriving at its inputs, the pulse frequency from the output of sensor b and, after appropriate transformations, indicates the angle of fuel injection ahead. If or VHB, then the pulse from the output of the former 10 is blocked by time selector II and the measurement does not occur. By cutting the pulse at the output of the comparator 8, the time selector 11 is reset to the initial state, which excludes the possibility that the generator 10 pulses pass to the measuring unit 7 when high-frequency oscillations intersect at the sensor output intersect the reference levels U and Ug.

The time selector 11 operates as follows.

The pulses from the output of the sensor 6 are fed to the input-converter 16, the output of which produces a constant voltage proportional to the frequency of these pulses. The signal from the output of the converter 16 is fed to the power inputs of the time of the driving circuits of the element 12 and the imaging unit 13. characterized by the corresponding constant time. The duration of the input pulse delay, formed by the element 12, and the pulse duration formed by the driver 13, are directly proportional to the corresponding time constant and inversely proportional to the control voltage, i.e. the pulse frequency at the output of the sensor. 6 As a result, the element 12 is set to a delay, the duration of which, regardless of the speed mode of the motor, corresponds to the rotation of the shaft by a fixed (reference) angle of 4.. Accordingly, in the imaging unit 13, the duration of the generated pulse is set, which, irrespective of the motor speed, corresponds to the rotation of the shaft to a fixed (reference)

the angle fo. min from the output of the comparator 8 is fed to the input of the former 15 and element 12. The latter triggers on the front of this pulse and when the shaft rotates through an angle, f, forms a pulse arriving on the front of the imager 13. The latter triggers

The time window is an impulse, the duration of which is delayed by an angle of 4 angle, the impulse from the output of the imaging unit 13 enters the control input of the switch 14 and unlocks it. In this state, the key connects the output of the imaging unit 10 to the corresponding input of the measuring unit 7. At the end of the pulse, the key is again locked.

By cutting the pulse from the output of the comparator 8, the shaper 15 triggers and generates a short pulse that goes to the first control inputs of the element 12 and the shaper 13, switches on the fast discharge circuit of the capacitors, the time of the driving circuits, and thus prepares the time selector I1 to form the next time window.

Introducing new elements — the second of the comparator, the time interval shaper, the pulse shaper, and the time selector — allows comparing the rise time of the pressure sensor signal with the permissible limits to eliminate the possibility of the appearance of false results that may occur when the noise at the output of the pressure sensor caused by parasitic deformations of the pipeline, and, consequently, increase the noise immunity of the device.

The execution of a time selector as a reference delay element, a reference time generator, a key, a pulse generator and a frequency converter allows the selection parameters to be independent of the frequency of rotation of the motor shaft and thereby expand the scope of application of the device.

Claims (2)

1. DEVICE FOR MEASURING ANGLE OF ADVANCE OF FUEL INJECTION IN THE INTERNAL COMBUSTION ENGINE; comprising a pressure sensor, an amplifier, a filter, a reference signal source, a first comparator, a top dead center mark sensor and a measurement unit, the pressure sensor being connected in series through an amplifier and a filter to a reference signal source, to the first output of which a first comparator connected to the output is connected amplifier, and the top dead center sensor is connected to the measuring unit, characterized in that, in order to improve accuracy by increasing noise immunity, a second comparator is additionally introduced into it, a time interval finder, a pulse shaper and a time selector, and the reference signal source is provided with a second output, the first input of the second comparator connected to the amplifier output, the second input to the second output of the reference signal source, and the output to the first control input of the temporary selector and the first input a shaper of time intervals, the second input of which is connected to the output of the first comparator, and the output is connected through a shaper to the input of a temporary selector, the output of which is connected to the second the input of the measuring unit, and the second control input with the output of the sensor marks the top dead center. _from 2. The device according to π. 1, characterized in that the time selector comprises a reference delay element, a reference time interval shaper, a key, a pulse shaper and a frequency converter, the reference delay element, a reference time interval shaper and a key connected in series, the first and second control inputs of the reference delay element and the shaper the reference time interval are connected respectively to the output of the pulse shaper and to the output of the frequency converter, the input of the pulse shaper connected with the input of the reference delay element, and the input of the frequency converter form the first and second control inputs of the temporary selector, respectively, and the input and output of the key are the input and output of the temporary selector, respectively. SU. „, 1173231