Method of determining test discharge parametres of capacitive ignition systems

FIELD: physics.

SUBSTANCE: method of determining test discharge parametres of capacitive ignition systems which consist of an ignition assembly, ignition cable and a spark plug, involves picking up a discharge current and voltage signal and determination of values of discharge parametres. The discharge current and voltage signal is picked up using analogue sensors. The current and voltage signals are picked up in auxiliary "short circuit" and "test load" modes, as well as in the main operation mode of the ignition system. Measurements are taken in digital form with given sampling frequency. Values of characteristic primary parametres are distinguished from measurement results. Values of intermediate parametres are determined for each assigned measurement mode using the obtained values of characteristic primary parametres. Values of test discharge parametres are determined using the obtained values of intermediate parametres.

EFFECT: possibility of measuring primary discharge parametres in digital form, picked up by analogue current and voltage sensors, more accurate measurement, obtaining information on efficiency of the spark plug and ignition system, discharge mode and energy factors and their change during operation or during an experiment.

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The invention relates to the field of measuring equipment, and in particular to methods of diagnostics of parameters of the discharges generated by the capacitive ignition systems used in aircraft engines and similar objects.

In the art of ignition systems is always of particular relevance was the task of determining with high accuracy the required list of discharge parameters characterizing the operating condition of the main elements of the ignition system, changing parametric status of these elements, the energy efficiency of the discharges and their flammable ability in the combustion chamber of the engine. The solution of this problem allows us to make a rational choice of the design parameters of ignition systems, process optimization ignition in the combustion chambers of aircraft engines, providing them with reliable start-up and safe operation of the corresponding objects in aeronautical engineering. Equipment, implements the solution, can be used for research purposes, in the development of ignition systems, control, maintenance, repair, testing when the engine starts and other

Known methods of measuring the duration of the discharge in the spark capacitive ignition systems and measuring the duration of the delay time between start of injection and the time of exposure of the fuel pin to the Torah, the candles, implemented in the devices described in the as of the USSR №1679416 from 23.09.91, and also in the patent RU 2210084 from 10.08.2003, and EN 2236019 from 10.09.2004,

The disadvantage of these technical solutions is that the signal from the analog current sensor or analog sensor voltages in the connection mode spark to the ignition wire is subjected to subsequent changes in analog form branched chain through various operational and logical elements, and the digitization of the final result of the measurement of the duration of the discharge or other parameter is only in the final stages of this chain of transformations. This circumstance is due to the limitation of measurement accuracy, defined nakaplivaemykh operating errors and logical elements through the entire chain of transformations. Despite the fact excludes the possibility of determining a large group of the most important parameters of the discharge, not amenable to direct measurement and determined only by calculation as a function of the primary parameters that are amenable to direct measurement.

The technical objective of the proposed method is the extension number of the defined parameters of the capacitive discharge ignition systems, as well as improving the accuracy of determination of the values of the duration of the discharge, obtaining information about the effectiveness of the spark and ignition unit.

T is Henichesk result is the ability to measure in digital form amenable to direct measurement of the primary parameters of the discharges, registered analog current sensors and voltage, improving the accuracy of measurements, information about the effectiveness of the spark and ignition system operation and energy performance when discharge changes during operation or in the course of the experiment.

The technical result of the claimed method of determination of diagnostic parameters of the capacitive discharge ignition systems, consisting of an ignition unit, ignition wires and spark plugs, is achieved by the fact that through the analog current sensors and voltage discharge to be included in the circuit of the ignition before the spark plug, register the signals of voltage and discharge current. The measurements were carried out in each of the following assigned load measuring modes: auxiliary mode "short circuit" - when connecting to the wire ignition instead of spark plugs shunt with zero resistance, in the auxiliary mode "load test" - when connecting to the wire ignition instead of spark plugs of known resistance values RTin native mode, the system by connecting it to the ignition wire spark plug, and the measurements are carried out in digital form, then record the current values of the signals from the sensor current i(t) and the sensor voltage u(t) at discrete points in time, following a given frequent is the sample rate. From measured and recorded values of signals and points in time for each of the three assigned modes are: characteristic values of the primary parameters of successive amplitudes of the damped wave current I1, I2, ..., In; the corresponding time coordinates of the points of passage of these amplitudes τ1τ2, ..., τn; temporary coordinate points beginning τ0and the end of τ00discharge; duration of the half wave τπ; the duration of the entire category of τ. Using the obtained characteristic values of the primary parameters for each of these three measurement modes, calculated for these modes, the values of the following intermediate parameters: circular frequency of vibration of a damped wave ωk, ωT, ω mode "short circuit"mode "load test", the primary mode of operation, respectively, calculate the logarithmic decrement bkbTb mode "short circuit"mode "load test"main operation mode", respectively. Using the obtained value of intermediate parameters, calculate the value of diagnostic parameters discharges: characteristic parameters of the discharge circuit unit and the ignition wire: resistance losses r, the equivalent inductance L, the equivalent capacitance C; characterized by the resistance of the discharge at the spark plug: equivalent resistance R eacting thermal resistance RDT; sensitive indicators of discharge in the ignition system: the initial discharge voltage of the capacitor Ucocurrent value of the discharge current ID; absolute energy values of discharge: initial cumulative energy of the capacitor Qcoenergy allocated to the spark plug Q, the energy losses in the discharge path Qrresidual energy of the capacitor Q; specific energy indicators of discharge: the coefficient of discharge η, the ratio of the stored energy γ, the coefficient of discharge of the accumulated energy λ.

Figure 1 shows a generalized block diagram of the capacitive ignition system for measurement of diagnostic parameters of digits.

Figure 2 presents the characteristic of the recorded signals of voltage and current.

Figure 3 presents the algorithm of analysis of the received signals of voltage and current.

Figure 1 shows a generalized block diagram of the ignition system, which marked the ignition system consists of: AZ - ignition unit, PZ - ignition wire SV - spark plug; and a system for measuring the discharge parameters consisting of: DT - analog sensor discharge current to the glow plug; DN - analog sensor voltage discharge at the spark; PC - personal computer (software); ADC - analog-to-digital conversion the user (data acquisition Board). As receivers of input signals from the measuring system used analog sensors voltage and current discharge impedance discharge parameters with the input of the ADC parameters. Sensor discharge current is a measuring current transformer, performed on the ferromagnetic core. The sensor is mounted in the high voltage ignition wire immediately before the spark plug. Sensor voltage discharge is a resistive voltage divider made on the Board, housed in a shielding metal case. The sensor is mounted directly on the end of the spark plug using the process cartridge, providing the contact terminals with the electrodes in the area of the working electrode gap at independent laboratory testing of the ignition system. On the discharge parameters, the sensor is not affected because of its large input resistance. In ensuring the connectivity of the sensor voltage to the input electrodes of the spark plug from the side of its shank when testing the system with the spark plug installed in the combustion chamber, is used spark plug adapter (not shown). This adapter for diagnostic purposes parametric element status bit circuit of the ignition system allows you to connect the resistive test load and the shunt to Otago circuit. As the ADC uses a high-speed card input, signal processing ADC is implemented by a personal computer.

Figure 2 shows the parameters characterizing the shape of the discharge pulses for oscillatory discharge when the discharge at the spark plug and at the discharge on resistive load: amplitude of current I1, I2, I3,..., In; temporary coordinates "zeros" τπ, 2τπ, 3τπ... and "highs" τ1τ2τ3...; the duration of the entire pulse τ. This is the primary measured parameters, as they can be determined by direct registration of the discharge pulse.

The analysis of the received signals is performed in the algorithm scheme is presented in figure 3.

Implementation of the proposed method for the determination of diagnostic parameters discharges capacitive ignition systems is as follows.

1. Enter the recording period T and the sampling frequency of the signal f.

2. Measured in digital form and record the current values of the signals from the sensor current i(t) and the sensor voltage u(t) at discrete points in time, following with a given sampling frequency, in each of the following three assigned load measuring modes:

in native mode, the system by connecting it to the ignition wire spark plugs;

in the secondary mode "short circuit" - when connecting to the wire ignition instead of spark plugs shunt with zero resistance;

in the secondary mode "load test" - when connecting to the wire ignition instead of spark plugs of known resistance values RT.

3. From measured and recorded values of signals and points in time for each of the three assigned modes select bit interval (the time of passage of the discharge and emit the characteristic values of the primary parameters of successive amplitudes of the damped wave current I1, I2, ..., In; the corresponding time coordinates of the points of passage of these amplitudes τ1τ2, ..., τn; temporary coordinate points beginning τ0and the end of τ00discharge; duration of the half wave τπnn-1the duration of the entire discharge τ=τ000.

4. Using the obtained characteristic values of the primary parameters for each of these three measurement modes, calculated for these modes, the values of the following intermediate parameters:

- circular frequency of vibration of a damped wave equations: ωk=π/τπ, ωT=π/τπ, ω=π/τπmode "short circuit"mode "load test", the primary mode of operation is relevant to the military;

logarithmic decrement according to the formula:

mode short circuit mode "load test", the primary mode of operation, respectively, while α is defined as

for each mode separately.

5. Using the obtained value of intermediate parameters, calculate the value of diagnostic parameters of discharge:

the characteristic parameters of the discharge circuit unit and the ignition wire size: resistance lossesequivalent inductanceequivalent capacity;

- the characteristic resistance of the discharge at the spark plug: equivalent resistanceacting thermal resistance

- modal indices of the discharge in the ignition system: the initial voltage of the capacitor dischargecurrent value of the discharge current

the absolute energy values of discharge: initial stored energy of the capacitorthe energy allocated to the spark plug

the energy of peterv bit path residual energy of the capacitor;

- specific energy performance discharge: the coefficient of dischargethe transfer ratio of the accumulated energythe coefficient of discharge of the accumulated energy

,

where T - time reception signal,

f is the sampling frequency of the signal,

i(t) is the signal from the current sensor,

u(t) is the signal from the sensor voltage

RT- resistance load test

τ0- the beginning of the discharge,

τ00- the time of discharge,

τπ- the duration of the half wave,

τ is the duration of the entire discharge

ωk, ωT, ω - circular frequency of oscillations of a damped wave for "short circuit", "load test" and the basic mode of operation, respectively,

bkbTb - logarithmic decrement for "short circuit", "load test" and the basic mode of operation, respectively,

r is the resistance losses

L is the equivalent inductance,

With equivalent capacity,

Reequivalent resistance

RDT- current thermal resistance

Uco- the initial discharge voltage of the capacitor

ID- the current value of the discharge current,

Qco- the initial stored energy of the capacitor

Q is the energy allocated to the spark plug

Qrenergy losses in the discharge path,

Qresidual energy of the capacitor

η is the coefficient of discharge,

γ is the ratio of stored energy,

λ is the coefficient of discharge of the accumulated energy.

The proposed method allows to measure directly in digital form amenable to direct measurement of the primary parameters of digits registered by analog current sensors and voltage. This increase in accuracy is achieved by increasing the sampling frequency f of the sensor signals by means of the ADC. The calculation of the quantities of all necessary discharge parameters in the above list is derived by the formula, linking them with the primary measured parameters, which gives information about the efficiency of the spark plugs and the ignition unit, the energetic and sensitive indicators of discharge, they are modified during operation or during a specific experiment.

The invention can be used to diagnose capacitive ignition systems for design, inspection, maintenance, repair, testing modern air-breathing engines of different types.

The method of determining the Oia diagnostic parameters of the capacitive discharge ignition systems, consisting of an ignition unit, ignition wires and spark plugs, namely, that through the analog current sensor and the analog sensor voltage discharge in the circuit of the ignition before the spark plugs, register the signal voltage and signal current discharge, determine the magnitude of the discharge parameters, such as the duration of the discharge, characterized in that the registration of a current signal and voltage signal is carried out in the following load measuring modes:
in auxiliary mode "short circuit", which is carried out when the connection cord plugs instead of spark plugs shunt with zero resistance;
in auxiliary mode "load test", which is carried out when connecting to the ignition wire together sparkplug resistance known values of RT;
in native mode, the ignition system, which is carried out when connecting to the ignition wire spark plug, and the measurements are carried out in digital form, then record the current values of the signals from the sensor current i(t) and the sensor voltage u(t) at discrete points in time, following with a given sampling frequency, and measured and recorded values of signals and points in time for each of the assigned modes emit characteristic values of the primary what parameters:
successive amplitudes of the damped wave current I1, Ia, ..., In;
the corresponding time coordinates of the points of passage of these amplitudes τ1τ2, ..., τn;
temporary coordinate points beginning τ0and the end of τ00discharge;
the duration of the half wave τπnn-1;
the duration of the entire discharge τ=τ000;
using the obtained characteristic values of the primary parameters for each of the assigned measurement modes calculate the value of intermediate parameters:
the circular frequency of vibration of a damped wave formulas ωk=π/τπ, ωT=π/τπ, ω=π/τπmode "short circuit"mode "load test", the primary mode of operation, respectively;
calculate the logarithmic decrement formulas

mode "short circuit"mode "load test", the primary mode of operation, respectively, with α defined as
for each mode separately;
using the obtained value of intermediate parameters, calculate the value of diagnostic parameters of discharge:
the characteristic parameters of the discharge circuit unit and the ignition wire:
weather resistance is the loss

the equivalent inductance

the equivalent capacitance

the characteristic resistance of the discharge at the spark plug:
equivalent resistance
the effective thermal resistance
modal parameters of the discharge in the ignition system:
the initial voltage of the capacitor discharge
the current value of the discharge current

the absolute energy values of discharge:
the initial stored energy of the capacitor
the energy released at the spark plug

energy losses in the discharge path
the residual energy of the capacitor
specific energy indicators of discharge:
the coefficient of discharge

the transfer ratio of the accumulated energy
the coefficient of discharge of the accumulated energy



 

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