Ion current measurement method for ignition plug with resonance structure and respective measurement device

FIELD: electricity.

SUBSTANCE: ignition plug (BR) is connected to generator (GEN) containing variable capacitor. The above generator includes also polarisation tools (MPOL) with option of ignition plug (BR) polarisation, which are connected between generator (GEN) and ignition plug (BR), and measurement instruments (MMES) for measurement of ion current at ignition plug (BR), which are connected between variable capacitor (Cb) and chassis ground.

EFFECT: improvement of measurement accuracy.

8 cl, 6 dwg

 

The present invention generally relates to the measurement of ionic current spark plugs, in particular spark plugs with a resonant structure that is designed for automotive ignition systems.

In particular, the invention relates to so-called "RF" ignition systems containing spark plugs with a resonant structure type multi-strike spark plugs or TOGETHER.

These ignition system that uses alternating currents described, for example, in French patent applications FR 2859830, FR 2589869, FR 2859831 filed on behalf of the applicant.

At the end of the compression cycle, the spark plug must create an electric arc, the energy of which is sufficient to initiate the process of ignition of the gas mixture contained in the combustion chamber of the engine.

This electric arc corresponds to ionization of the gas mixture between the electrodes of the spark plugs, respectively, the positive Central electrode and the bulk electrode.

However, during the combustion of the mixture after generating the spark plug sparks can be expansion of the flame front. He may discard a portion of the mixture in the direction of the cylinder wall and the piston head.

The increase of pressure and temperature occurs so rapidly that the fuel may remain pinned to the walls, to reach its point of ignition and Gosplan Nitsa in several places.

In the microexplosions occur, causing vibration in the acoustic frequency range (approximately from 5 to 10 kHz). These vibrations are very intense and can quickly create hot spots, which further exacerbate the problem. A series of small explosions tearing or melts a small amount of metal on the head of the piston and/or cylinder wall, which may eventually lead to the destruction of the piston and cylinder wall.

The appearance of these detonation phenomena can be detected by measuring the ion current, i.e. the current passing through the spark plug. Indeed, the ion current is manifested in the spark plug in such a manner as if the contact of the electrodes temporarily connect the resistance (in first approximation).

For this measurement tools or sensors must be able to work in a very narrow bandwidth, for example of the order of 7 kHz.

The present invention is directed to create a current measurement of polarization for spark plugs with resonant structures.

Another objective of the invention is to provide a measuring accurate enough to work in the desired narrow frequency bandwidth.

In this regard, an object of the present invention is a method of measuring ion current spark plugs with a resonant structure, which is equipped with the car is the ignition system, which at the time of the phase plug to the specified spark plug serves voltage generated using a pre-charged capacitor is a variable capacitor.

According to the invention specified ion current is measured between the specified variable capacitor and weight periodically between two phases ignition, after polarization of the spark plugs.

In other words, instead of measuring the ion current at the spark plugs that would need to be done to solve this problem, this ion current is measured directly at the level of the variable capacitor feeding the spark plug during its discharge.

Therefore, the inaccuracy of the measurement is reduced to a minimum.

According to a variant implementation of the specified ion current measured by the measuring means, connected between the specified variable capacitor and weight and lockable in the short time phase ignition.

In other words, the measurement means connected only between two phases of the ignition.

According to another variant implementation of the ion current measured at the end of phase decay, during which the current passing through the spark plug, gradually decreases.

Another object of the invention is a device for measuring ion current spark plugs with a resonant structure, which of the are equipped automobile ignition system, while specified spark plug connected to a generator that contains a variable capacitor.

According to the invention the specified generator further comprises means polarization made with the possibility of polarization of spark plugs connected between the generator and the spark plug, and means for measuring the ion current spark plugs, connected between the variable capacitor and mass.

Thus, since the measurement means connected between the variable capacitor and the mass, but not directly to the contacts of the spark plugs, you can choose the polarization resistance of the spark plug with low value adapted to the strength of the ion current, which is typically less than 1 mA, and to a specific frequency band, such as frequency band, in which the observed detonation phenomena.

Preferably the device may further comprise managed funds short circuit is arranged to short circuit measurement.

For example, the measuring may include measuring the resistance.

According to a variant of execution means a short circuit may include a transistor short circuit, connected between the variable capacitor and the mass and driven generator voltage Korotkov the circuit, and the power source polarization, is connected between the measuring resistance and weight and made with the possibility of polarization of the specified transistor short circuit.

According to a variant of execution of the power source polarization may contain, on the one hand, resistance power and the local power source connected in series, and, on the other hand, the capacitor power supply connected in parallel with the resistance power and the local power source between the measuring resistance and weight.

Other advantages and features of the present invention will be more apparent from the following detailed description of the scenarios, presented as a non-restrictive example, with reference to the accompanying drawings, on which:

figure 1 - an embodiment of the invention;

figure 2 is a more detailed diagram of a variant implementation of the invention;

figure 3 is a more detailed view of a module according to a variant implementation of the invention;

4 is a chronogram of the different stages of a variant implementation of the invention;

5 and 6 embodiments of the another block of the invention.

Figure 1 is a General position SYS marked ignition system for a motor vehicle comprising a spark plug BR with resonant structure, well known in the art and described, for example, in the French paten the different applications FR 2859830, FR 2589869, FR 2859831 filed on behalf of the applicant.

Through the spark plug BR undergoes ion current Ii.

In particular, as schematically shown in figure 1, the spark plug BR contains a resonant node RSI (called spark ignition - coil)containing the inductor L1 and the capacitor C1, which in this example contains site: basement 1 - ceramics 2 - the Central electrode 3.

Spark plug BR is connected to the generator GEN, configured to generate a voltage, called the "intermediate voltage", with a high value. This high voltage is supplied through the Central electrode 3 of the capacitor C1. When electric current flows between the Central electrode 3 and the mass electrode 4, an electric arc, generating a spark 5.

Spark plug BR is connected to the generator GEN through the stage of DHT, called "block high voltage, sequentially connected by means of junction MDEC. Tools polarization MPOL spark plugs connected in parallel with block high voltage DHT and with means of isolation MDEC.

The generator GEN contains measurement tools MMES made with the possibility of measuring the ion current Ii flowing in the spark plug BR.

Figure 2 in more detail shows a variant of execution units of the system SYS in accordance with the present invention.

The generator GEN can be done is n by using the wiring diagrams of the voltage-type "booster", as it is known by experts.

The generator GEN contains the power supply Vbat, in this case at 12, made with the possibility of recharging coil GALLIGENA, called "tank", which is connected to the first contact b1 to the power supply Vbat. Charging coil GALLIGENA is controlled by the transistor M1 connected between the other contact b2 of coil GALLIGENA and mass. The transistor M1 is controlled by the generator voltage GM1.

Coil-tank GALLIGENA is discharged in part of the circuit connected to its contact b2, through the rectifier diode DR at a voltage exceeding the voltage of 12 V, generated by the power source Vbat. This relatively high voltage is called the "intermediate voltage Vint. It is in the order of hundreds of volts. In order to maintain essentially constant the value of this intermediate voltage Vint, generator GEN contains the so-called "ballast" capacitor Cb connected to the output rectifier diode DR.

The generator GEN is connected to the unit high voltage DHT, fed by the intermediate voltage Vint and manageable controls MSOM using the control signal Scom.

The control signal Scom is directly involved in the implementation of the generation of sparks spark plug BR.

Figure 3 shows an example of execution of a block of high voltage DHT.

It contains the node formed by the coil L2 and the capacitor C2, the United States in parallel, and receiving at the input the intermediate voltage Vint.

At the output node L2-C2 is connected to the transistor M5 control, receiving at its control electrode, the control signal Scom.

The control signal Scom meets periodically generated series of pulses.

Thus, when each of a series of pulses the transistor M5 is charging the coil L2, which resonates with the capacitor C2 and the resonance node RS1, generating high-voltage pulses at the natural frequency of the coil BR.

When a resonant node RS1 is excited at the natural frequency and the index of q is high (e.g. greater than 40), on the contacts of the capacitor C1 appears ultrahigh voltage. Thus, on the Central electrode of the spark plug BR, which is one of the contacts of the capacitor C1, there is the ultra-high voltage, causing a spark.

Let us return to figure 2.

The excitement generated by block high voltage DHT, is transmitted to the resonance structure RS1 spark BR through the junction MDEC, in this case, the decoupling capacitor Cd.

The decoupling capacitor Cd prevents continuous communication between the intermediate voltage Vint and the Central electrode 3 spark plugs. This interruption allows you to avoid electric shock or electrocution of the person.

In addition, if n is Chinese discharge type "electric arc", it can lead to rapid destruction of the electrodes, in particular of the Central electrode 3. Indeed, if the spark with a sufficiently high specific conductivity occurs between the Central electrode and the mass, its accompanying voltage drop can reach values lower than the intermediate voltage Vint. All the charges accumulated in the capacitor Cd, in this case, transmitted to the link created by the spark. This transfer of charge occurs with strong currents that can damage the Central electrode 3.

The function of the decoupling capacitor Cd is to prevent such transmission charges.

In a variant, the generator may be a transformer, in the form of a step-up transformer, which prevents the transfer of DC. In this case, there is no need to use a capacitor junction.

To enable measurement of the ion current, use polarization MPOL to save predominantly positive polarization after generating sparks at the Central electrode 3 spark plug BR.

Classically funds polarization MPOL can be made in the form of resistance Rpol connected between the output of the rectifier diode DR, feeding the intermediate voltage Vint, and the release of funds junction MDEC, in this case, the capacitor Cd.

A simple solution to change the value of the ion current in this case would be connected to the contacts of the polarization resistance Rpol scheme, made with the possibility of dividing the value of voltage conversion divided thus the voltage values in the current and then measure the current.

These are well-known specialists of the classical scheme can be implemented using a differential amplifier with a discrete transistor or an operational amplifier, or by using a schema that uses reflectors current. However, these circuit containing a voltage divider that reduces the accuracy required for measuring very weak ion current.

In contrast to these solutions according to the present invention it is proposed to use the polarization resistance low resistance value, in order to maintain maximum accuracy when measuring the ion current, while measuring devices connected to the contacts of the polarization resistance Rpol, and between the capacitor Cb and the mass inside the generator GEN.

These measurement tools MMES contain the measuring resistance Rm and the measuring contact Bm, which measure the ion current.

In addition, these measurement tools MMES interact with the means of a short circuit MSS containing the interrupter INT, connected in parallel with the measuring resistance Rm, and the interrupter INT is controlled by the generator short circuit of GCC.

Preferably the breaker is if tridactylum and has a very low impedance.

Figure 4 shows the various stages of a variant embodiment of the invention during the period T.

At the time t0, the transistor M1 becomes permeable and allows charging of the capacitor Cb.

At the time t1, the control signal Scom actuates the transistor M5 by means of pulsed control signal (pulse frequency is, for example, 5 MHz), and begins phase ignition and generation of a spark by the spark plug BR. At the time t2, the control signal again becomes inactive.

During phase attenuation (between t2 and t3) current ignition (high amplitude) naturally and gradually decreases in the spark plug BR due to the presence of parasitic resistances.

Between the moments t0 and t3 means short circuits are active and shorts measuring resistance. Therefore, the capacitor Cb is connected between the rectifier diode DR and mass.

At the time t3, the transistor M2 deactivates the means of a short circuit, and the capacitor Cb is discharged through the measuring resistance Rm. The current discharge of the capacitor Cb corresponds to the ion current, which passes through the resistance Rpol, in the spark plug BR and then in the fuel mixture.

The value of the ion current measured at the level of the measuring contact Bm.

The phase measurement is completed in mo is UNT t4, and at the time t5 begins another cycle of charging, ignition and measurements.

Figure 5 shows the embodiment of the interrupter INT. In this example, the controlled interrupter in the form of a transistor, in this case the type MOS transistor M2, a control electrode which is connected to the generator GCC. In order to prevent the diode effect of the MOS transistor M2, produce polarization using the power source polarization Apol connected between the measuring resistance Rm and mass.

Figure 6 shows an embodiment of the power source polarization Apol.

In this example, the power source polarization Apol includes a capacitor Cal connected to the local power source through Aloe resistance power Ral. Local power supply Aloe can represent, for example, the battery or the battery voltage of the 5th Century

Specialist it is easy to determine the parameters of components used to determine the voltage Val on the contacts of the capacitor Cal. From this voltage value Val output ion current Ii using the formula:

Ii=(_Apol-Napryazheniem)/Rm

Thus, the invention allows to measure the ion current very accurately and in a defined frequency range, for example, corresponding to the detection of detonation phenomena.

1. A method of measuring ion current spark plugs with Rezo is annoy structure, which is equipped with an automotive ignition system, namely, that during the phase of ignition at the spark plug (BR) serves voltage generated using a pre-charged capacitor is a variable capacitor (Cb)with ion current (Ii) measure between the specified variable capacitor (Cb) and weight periodically, between two phases of the ignition, after the polarization spark plugs (BR).

2. The method according to claim 1, in which the ion current is measured by the measuring means, connected between the specified variable capacitor (Cb) and weight and lockable in the short time phase ignition.

3. The method according to claim 1 or 2, in which the ion current measured at the end of phase decay, during which the current passing through the spark plug, gradually decreases.

4. Device for measuring ion current spark plugs with a resonant structure, which is equipped with an automotive ignition system that contains connected with a spark plug (BR) generator (GEN), which includes a variable capacitor, means of polarization (MPOL)made with the possibility of polarization of the spark plugs (BR)connected between the generator (GEN) and the specified spark plug (BR), and measurement tools (MMES) ion current specified spark plugs (BR)connected between the capacitor (Cb) to a variable capacity and mass.

5. The device according to claim 4, further containing managed funds short circuit (MCC), made with the possibility of short circuit measurement (MMES).

6. The device according to claim 5, in which these measurement tools (MMES) includes measuring resistance (Rm).

7. The device according to claim 5 or 6, which means a short circuit (MCC) includes a transistor short circuit (M2)connected between the variable capacitor (Cb) and mass and driven generator voltage short circuit (GCC), and the power source polarization (Apol)connected between the measuring resistance (Rm) and weight and made with the possibility of polarization of the specified transistor short circuit.

8. The device according to claim 7, in which the power source polarization contains resistance power (Ral) and the local power source (Aloe), connected in series, and capacitor power (Cal)connected in parallel with the resistance power (Ral) and with a local power source (Aloe), between the measuring resistance (Rm) and mass.



 

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