JP2011169179A - Ignition device and ignition method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve combustion efficiency of an internal combustion engine, by emitting radio waves at an appropriate frequency according to an operating environment. <P>SOLUTION: The ignition device includes: a high-frequency voltage generator 2 generating high-frequency voltage; an electromagnetic radiator 5 performing electromagnetic radiation into a combustion chamber, based on the high-frequency voltage generated by the high-frequency voltage generator 2; an incident/reflected wave voltage measure 4 disposed between the high-frequency voltage generator 2 and the electromagnetic radiator 5 to measure incident wave voltage to the electromagnetic radiator 5, and the reflected wave voltage therefrom; and a high-frequency voltage controller 1 controlling high-frequency voltage generated by the high-frequency voltage generator 2, based on the incident wave voltage and the reflected wave voltage measured by the incident/reflected wave voltage measure 4. The high-frequency voltage controller 1 controls the high-frequency voltage generated by the high-frequency voltage generator 2, based on a ratio of the reflected wave voltage with respect to the incident wave voltage. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an ignition device and an ignition method for igniting an air-fuel mixture in a combustion chamber of an internal combustion engine.

  Conventionally, in order to improve the efficiency of an internal combustion engine, it has been widely recognized that dilution of a fuel mixture (hereinafter simply referred to as an air-fuel mixture) is effective. However, in an internal combustion engine that ignites by the discharge energy generated by applying a substantially DC voltage to the spark plug (ignition plug), there is a limit to the ignition and combustion of the lean air-fuel mixture by the spark plug, and the lean mixture I couldn't combust stably.

  As a countermeasure against such a problem, an ignition device that enables combustion of a lean air-fuel mixture by radiating high-frequency electromagnetic waves to the air-fuel mixture and supplying electromagnetic energy is disclosed (for example, Patent Documents). 1).

JP 51-77719 A

  The frequency of the electromagnetic wave radiated to the mixture needs to be appropriate, but the frequency varies depending on the operating environment such as the combustion state of the mixture and the state of the combustion chamber. Therefore, it is necessary to radiate electromagnetic waves having an appropriate frequency according to changes in the operating environment. In the conventional ignition device, a method for emitting an electromagnetic wave having an appropriate frequency according to the operating environment has not been disclosed.

  The present invention has been made to solve these problems, and an object thereof is to improve the combustion efficiency of an internal combustion engine by radiating electromagnetic waves having an appropriate frequency according to the operating environment.

  In order to solve the above problems, an ignition device according to the present invention is an ignition device for igniting an air-fuel mixture in a combustion chamber of an internal combustion engine, which is generated by a DC pulse generating means for generating a DC pulse and a DC pulse generating means. DC pulse discharge means for performing DC pulse discharge in the combustion chamber based on the direct current pulse, high-frequency voltage generation means for generating high-frequency voltage, and electromagnetic wave radiation in the combustion chamber based on the high-frequency voltage generated by the high-frequency voltage generation means An electromagnetic wave radiating means, an incident / reflected voltage measuring means provided between the high frequency voltage generating means and the electromagnetic wave radiating means, for measuring the incident voltage incident on the electromagnetic wave radiating means and the reflected reflected voltage, and incident / reflected voltage measurement High-frequency voltage control means for controlling the high-frequency voltage generated by the high-frequency voltage generation means based on the incident voltage and the reflected voltage measured by the means. Control means, based on the ratio of reflected voltage to incident voltage, and controlling the high-frequency voltage generated by the high-frequency voltage generating means.

  According to the present invention, the incident / reflected voltage measuring means, which is provided between the high-frequency voltage generating means and the electromagnetic wave radiating means, measures the incident voltage incident on the electromagnetic wave radiating means and the reflected reflected voltage, and the incident / reflected voltage measurement. High-frequency voltage control means for controlling the high-frequency voltage generated by the high-frequency voltage generation means based on the incident voltage and the reflected voltage measured by the means, the high-frequency voltage control means based on the ratio of the reflected voltage to the incident voltage Since the high frequency voltage generated by the voltage generating means is controlled, it is possible to improve the combustion efficiency of the internal combustion engine by radiating electromagnetic waves having an appropriate frequency according to the operating environment.

1 is a block diagram of an ignition device according to an embodiment of the present invention. It is explanatory drawing of the incident / reflection voltage measuring means by embodiment of this invention. It is a block diagram of the high frequency voltage control means by embodiment of this invention. It is the figure which showed an example which attaches the ignition device by embodiment of this invention to an engine. It is a block diagram of the ignition device by a base technology. It is a graph which shows an example of the reflected power ratio of a general spark plug.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, the technology that is the premise of the present invention will be described.

  FIG. 5 is a configuration diagram of an ignition device according to the base technology (Patent Document 1), and shows a specific example of an ignition device installed in a four-cylinder internal combustion engine. As shown in FIG. 5, the oscillator 17 generates a high-frequency voltage using electric power supplied from the battery 15 and the generator 16 via the control box 21. The generated high frequency voltage is supplied to the spark plugs 22.1 to 22.4 via the coaxial cable 18, the coaxial relay switch 24, and the high voltage DC blocking devices 20.1 to 20.4. On the other hand, after the DC high voltage is distributed by the distributor 25, it is supplied to the spark plugs 22.1 to 22.4 via the terminal 23.3, the coaxial cable 18a, and the low-pass filters 19.1 to 19.4. Supplied. The high-frequency voltage and the DC high voltage are sequentially supplied to any one of the spark plugs 22.1 to 22.4.

The high-frequency voltage (operating frequency) generated by the oscillator 17 is approximately the operating frequency of the plasma frequency f _ps of the charged particle species of the air-fuel mixture in the air-fuel mixture supplied into the combustion chamber, or about 10 ⁶ Hz to about 10 The frequency is ¹² Hz or less. Here, the plasma frequency f _ps is expressed as the following equation (1).

Here, n is the number density of charged particle species, e is the amount of charge of electrons, m is the mass of the charged particle species, and ε ₀ is the permittivity of free space.

As is clear from equation (1), the plasma frequency f _ps of the charged particle species depends on the number density n of the charged particle species. Since the number density n of the charged particle species varies greatly according to the combustion state of the air-fuel mixture, the plasma frequency f _ps also varies greatly accordingly. Therefore, the high-frequency voltage (operating frequency) generated by the oscillator 17 needs to be adjusted in accordance with the changing plasma frequency f _ps , but such a method has not been disclosed. Moreover, since the frequency band of about 10 ⁶ Hz or more and about 10 ¹² Hz or less is very wide, it does not always radiate electromagnetic waves having an appropriate frequency. Thus, the conventional ignition device has a problem that it is difficult to improve the combustion efficiency of the internal combustion engine.

  Moreover, in a general high frequency electromagnetic wave radiation circuit, a reflected wave may be formed according to the frequency of incident high frequency (high frequency incident on the radiation means). Such a reflected wave causes problems such as generation of heat in the circuit and damage of circuit elements such as an amplifier. In a circuit including radiation means such as a spark plug that radiates electromagnetic waves into the combustion chamber of an internal combustion engine, the reflected wave changes greatly due to the physical dimensions of the radiation means and the combustion chamber and the influence of the gas state in the combustion chamber.

  When a general spark plug is also used as a radiation means, the spark plug is designed for efficient discharge when a DC pulse is applied. Therefore, the frequency of the electromagnetic wave that efficiently radiates the applied high-frequency voltage is reduced. The range becomes very narrow. When electromagnetic waves are radiated at a frequency outside such a frequency range, a reflected wave is formed, returning to the high-frequency voltage supply side, causing the above-described problems. Therefore, precise control of the frequency of the incident high frequency is required.

  When a high frequency signal is incident on the spark plug, the ratio of the reflected voltage to the incident voltage to the spark plug (hereinafter referred to as the reflected voltage ratio) and the ratio of the reflected power to the incident power (hereinafter referred to as the reflected power ratio) are measured. Is possible. FIG. 6 is a graph showing an example of a reflected power ratio of a general spark plug. The spark plug radiates efficient electromagnetic waves (hereinafter, unless otherwise specified, the spark plug is efficient). It shall also be used as a radiation means for radiating electromagnetic waves). As shown in FIG. 6, the reflected power ratio decreases only at a specific frequency, and increases at other frequencies. In addition, there is a spark plug in which the reflected power ratio increases by 10 times or more only by changing the frequency by about 1%. The frequency at which the reflected power ratio decreases is different for each of the same type of spark plugs, and shows time variations (variations due to changes in the operating environment) even for the same spark plugs.

  From the above, if the incident high-frequency signal (incident high-frequency voltage) can be controlled in response to changes in the operating environment of the same type of individual spark plug or the same spark plug, even if it is used as an antenna for high-frequency electromagnetic wave radiation Even if a spark plug with insufficient performance is used, it is possible to efficiently radiate electromagnetic waves and improve the combustion efficiency of the air-fuel mixture. An object of the present invention is to improve the combustion efficiency of an internal combustion engine by radiating radio waves having an appropriate frequency according to the operating environment, which will be described in detail below.

<Embodiment 1>
FIG. 1 is a block diagram of an ignition device according to an embodiment of the present invention. As shown in FIG. 1, the ignition device according to the present embodiment is an ignition device that ignites an air-fuel mixture in a combustion chamber of an internal combustion engine, and includes a DC pulse generating means 3 that generates DC pulses and a DC pulse generating means 3. Based on the generated direct current pulse, direct current pulse discharge means 6 for performing direct current pulse discharge in the combustion chamber, high frequency voltage generation means 2 for generating high frequency voltage, and high frequency voltage generated by the high frequency voltage generation means 2, An electromagnetic wave radiating means 5 (spark plug) that radiates electromagnetic waves, and is provided between the high frequency voltage generating means 2 and the electromagnetic wave radiating means 5, and measures an incident voltage incident on the electromagnetic wave radiating means 5 and a reflected voltage reflected. The high-frequency voltage generated by the high-frequency voltage generating means 2 is controlled based on the incident-reflected voltage measuring means 4 and the incident voltage and reflected voltage measured by the incident-reflected voltage measuring means That a high frequency voltage control means 1, the high-frequency voltage control means 1, based on the ratio of reflected voltage to incident voltage is characterized by controlling the high-frequency voltage generated by the high-frequency voltage generating means 2. The ignition device shown in FIG. 1 may be attached to an engine as shown in FIG. 4, 71 is a plug hole, 72 is a spark plug for realizing the functions of the electromagnetic wave radiation means 5 and the DC pulse discharge means 6, 73 is a combustion chamber, 74 is a piston, 75 is a combustion chamber wall, and 76 is an intake valve. , 77 are exhaust valves, 78 is an intake passage, and 79 is an exhaust passage.

  The high frequency voltage generating means 2 generates a voltage so as to be in an appropriate frequency range with respect to the electromagnetic wave radiating means 5 in the standard state. As a specific example, a high frequency voltage may be generated by amplifying a voltage generated by a known crystal oscillator using a known amplifier. The high-frequency voltage thus generated is radiated after being transmitted to the electromagnetic wave radiation means 5. For transmission to the high-frequency radiation means 5, a normal high-frequency coaxial cable or other known means may be used.

  FIG. 2 is an explanatory diagram of the incident / reflected voltage measuring means 4 according to the embodiment of the present invention. As shown in FIG. 2, the incident / reflected voltage measuring means 4 includes directional couplers 41 and 42. The directional coupler 41 generates an incident voltage by inducing an incident high frequency incident on the electromagnetic wave radiating means 5 with a constant coupling. Further, the directional coupler 42 generates a reflected voltage by inducing the reflected high frequency reflected from the electromagnetic wave radiation means 5 with a constant coupling. The directional couplers 41 and 42 may be known directional couplers. The incident voltage and the reflected voltage generated in this way are each sampled by a known analog-digital converter.

  The electromagnetic wave radiating means 5 may be a general spark plug, a spark plug shown in FIGS. 1 to 7 of Patent Document 1, or other known means.

  The DC pulse generating means 3 may be configured using a known ignition coil. The direct current pulse discharge means 6 may be the same device as the electromagnetic wave radiation means 5 or may be a different device. In addition, when using as the same apparatus, you may use the above-mentioned general spark plug or the spark plug shown in FIGS.

  FIG. 3 is a block diagram of the high-frequency voltage control means 1 according to the embodiment of the present invention. As shown in FIG. 3, the high frequency voltage control unit 1 includes a processor 11 in order to realize the input / output relationship in the high frequency voltage control unit 1. The processor 11 may be configured using a known microcomputer.

  The high-frequency voltage control means 1 inputs a part or all of the crank angle, the rotational speed, the fuel injection amount, the air fuel cost, and the ignition timing state signal necessary for controlling the high-frequency voltage. A state signal input port 12 for performing sampling, a sampling control signal output port 13 for outputting a control signal for controlling sampling at the incident / reflected voltage measuring means 4 to the incident / reflected voltage measuring means 4, and an incident / reflected voltage measuring means 4 In order to control the generation of the high-frequency voltage and the sample-value input port 14 for inputting the sample value collected at, a part or all of the control signals of the frequency, voltage and timing signal are sent to the high-frequency voltage generating means 2. And a high-frequency voltage control signal output port 15 for output. The incident voltage and the reflected voltage measured by the incident / reflected voltage measuring means 4 may be sampled using an analog-digital converter installed in a microcomputer constituting the processor 11. Further, the high-frequency voltage control means 1 includes a storage device 16 and records a plurality of sample values, predetermined parameter values, and part or all of the standard control program.

  The high-frequency voltage control means 1 may store standard standard control in the storage device 16 in advance. In the standard control, the relationship between the state signal of the internal combustion engine and the high-frequency voltage generation signal may be stored in the form of a table.

  Next, a method for sampling the incident voltage and the reflected voltage measured by the incident / reflected voltage measuring means 4 will be described.

  The incident / reflected voltage measuring means 4 samples the incident voltage and the reflected voltage, preferably in the exhaust-intake process of the internal combustion engine. That is, the high-frequency voltage control means 1 performs sampling control in the exhaust-intake process of the internal combustion engine. Sampling may be performed a plurality of times, and is arbitrarily controlled by the high-frequency voltage control means 1.

  The piston position in the exhaust-intake process corresponds to the piston position in the compression-explosion process (that is, the physical dimensions of the combustion chamber are the same), and the internal combustion engine in the compression-explosion process is the same except for the mixture state. The electromagnetic characteristics in the combustion chamber (cylinder) are reproduced. In this way, by radiating electromagnetic waves in the exhaust-intake process, measuring the incident voltage and the reflected voltage, and performing sampling, the electromagnetic waves are smaller than the power required for the electromagnetic waves radiated in the compression-explosion process. Can be radiated to save power. In addition, since the electromagnetic interaction is linear, after measuring the incident voltage and the reflected voltage with low power in the exhaust-intake process, the incident voltage measured in the compression-explosion process in which electromagnetic waves are emitted with high power and The reflected voltage can be estimated.

  The ignition device according to the present embodiment compares the high-frequency voltage generated by the high-frequency voltage generation means 2 and the incident voltage when the high-frequency voltage enters the electromagnetic wave radiation means 5 with a predetermined parameter. Means for confirming the normality of the operation may be further provided. In the exhaust-intake process, the high-frequency voltage control means 1 controls the high-frequency voltage used for electromagnetic wave radiation at the time of standard control and / or in the vicinity thereof to generate an electromagnetic wave as a minimum voltage that can ensure a signal-to-noise ratio. The incident voltage and reflected voltage measured by the incident / reflected voltage measuring means 4 may be sampled. At this time, the generated electromagnetic wave may be sampled at the time of standard control and at a plurality of frequencies in the vicinity thereof. The collected sample values may be stored in the storage device 16 together with the parameters.

  The frequency of the high-frequency voltage generated by the high-frequency voltage generation means 2 appropriately controlled by the high-frequency voltage control means 1 is searched using the greedy method or the tabu research method for the sample values of the incident voltage and the reflected voltage. May be. Alternatively, a statistical test may be performed to determine whether the frequency of the high-frequency voltage generated by the high-frequency voltage generation means 2 is appropriate using a plurality of sample values. If the frequency is determined to be appropriate as a result of the test, the frequency may be used as the frequency of an appropriate high-frequency voltage in the compression-explosion process.

  From the above, the high-frequency voltage control means 1 samples the incident voltage and the reflected voltage measured by the incoming / reflected voltage measuring means 4, and the high-frequency voltage generated by the high-frequency voltage generating means 2 based on the ratio of the reflected voltage to the incident voltage. Therefore, it is possible to improve the combustion efficiency of the internal combustion engine by emitting electromagnetic waves having an appropriate frequency according to the operating environment. Moreover, since the high frequency voltage control means 1 controls the sampling of the incident voltage and the reflected voltage in the exhaust-intake process, the high-frequency voltage control means 1 generates an electromagnetic wave with a power smaller than that required for the electromagnetic wave radiated in the compression-explosion process. It suffices to radiate, and power saving can be achieved during sampling control.

<Embodiment 2>
In the second embodiment of the present invention, the incident / reflected voltage measuring means 4 measures the incident voltage and the reflected voltage in the compression-explosion process of the internal combustion engine, and the high-frequency voltage control means 1 determines the incident voltage and the reflected voltage. Sampling control is performed by performing a plurality of ignition cycles at the same timing under the same operating conditions of the internal combustion engine. Other configurations and operations are the same as those in the first embodiment, and thus description thereof is omitted here.

  When electromagnetic waves having a frequency that is accepted by the air-fuel mixture in the compression-explosion process are radiated from the electromagnetic wave radiation means 5, the air-fuel mixture receives more electromagnetic energy (electric power) than electromagnetic waves of other frequencies at that frequency. The electric power that the electromagnetic wave radiated from the radiating means 5 reflects back from the combustion chamber decreases (that is, the reflected power ratio decreases). The frequency that the air-fuel mixture accepts generally varies depending on the state of the air-fuel mixture, but the high-frequency voltage control means 1 controls the sampling of the incident voltage and the reflected voltage at the same timing under the same operating conditions of the internal combustion engine. By applying a statistical test after performing multiple ignition cycles, it is possible to estimate the frequency of the electromagnetic wave received by the mixture within a range of reliability. Note that the estimated frequency of the electromagnetic wave may be stored in the storage device 16 of the high-frequency voltage control means 1.

  From the above, it is possible for the high frequency voltage control means 1 to improve the combustion efficiency of the internal combustion engine by controlling the high frequency voltage generation means 2 so as to generate a high frequency voltage at the frequency of the electromagnetic wave received by the air-fuel mixture. It becomes.

<Embodiment 3>
In Embodiment 3 of the present invention, the incoming / reflected voltage measuring means 4 measures the incident voltage and the reflected voltage in the compression-explosion process of the internal combustion engine, and the high-frequency voltage control means 1 Sampling control is performed a plurality of times per ignition cycle of the internal combustion engine. Other configurations and operations are the same as those in the first embodiment, and thus description thereof is omitted here.

  When electromagnetic waves are radiated from the electromagnetic wave radiation means 5 in the compression-explosion process, a new conductor appears when plasma is generated in the air-fuel mixture, and the appearance of such plasma is an increase in the reflected power ratio. It can be observed.

  The power of the electromagnetic wave necessary for maintaining the generated plasma may be smaller than the power of the electromagnetic wave necessary for generating the plasma. In this case, by reducing the high-frequency voltage generated by the high-frequency voltage generating means 2 It is possible to suppress the power of electromagnetic waves to be radiated (incident power). The high frequency voltage control means 1 controls the high frequency voltage generated by the high frequency voltage generation means 2.

  From the above, when plasma is generated in the air-fuel mixture by radiating electromagnetic waves, it is possible to suppress the power (incident power) of the electromagnetic waves to be radiated by lowering the high frequency voltage generated by the high frequency voltage generating means 2 It becomes.

  DESCRIPTION OF SYMBOLS 1 High frequency voltage control means, 2 High frequency voltage generation means, 3 DC pulse generation means, 4 Incidence reflection voltage measurement means, 5 Electromagnetic radiation means, 11 Processor, 12 State signal input port, 13 Sampling control signal output port, 14 Sampling value Input port, 15 High frequency voltage control signal output port, 16 Storage device, 41, 42 Directional coupler, 71 Plug hole, 72 Spark plug, 73 Combustion chamber, 74 Piston, 75 Combustion chamber wall, 76 Intake valve, 77 Exhaust valve 78 Intake passage, 79 Exhaust passage.

Claims (12)

An ignition device for igniting an air-fuel mixture in a combustion chamber of an internal combustion engine,
DC pulse generating means for generating a DC pulse;
DC pulse discharge means for performing DC pulse discharge in the combustion chamber based on the DC pulse generated by the DC pulse generation means;
High-frequency voltage generating means for generating a high-frequency voltage;
Based on the high-frequency voltage generated by the high-frequency voltage generation means, electromagnetic wave radiation means for radiating electromagnetic waves in the combustion chamber;
Incident reflection voltage measuring means provided between the high frequency voltage generating means and the electromagnetic wave radiating means, and measuring an incident voltage incident on the electromagnetic wave radiating means and a reflected reflected voltage;
High-frequency voltage control means for controlling the high-frequency voltage generated by the high-frequency voltage generation means based on the incident voltage and the reflected voltage measured by the incident-reflection voltage measurement means;
With
The ignition device according to claim 1, wherein the high-frequency voltage control means controls the high-frequency voltage generated by the high-frequency voltage generation means based on a ratio of the reflected voltage to the incident voltage.   2. The ignition device according to claim 1, wherein the high-frequency voltage control unit controls sampling of the incident voltage and the reflected voltage measured by the incident / reflected voltage measuring unit.   The ignition apparatus according to claim 2, wherein the high-frequency voltage control means performs the sampling control in an exhaust-intake process of the internal combustion engine.   The ignition device according to claim 2, wherein the high-frequency voltage control unit performs the sampling control in a compression-explosion process of the internal combustion engine.   5. The ignition device according to claim 4, wherein the high-frequency voltage control means performs the sampling control a plurality of ignition cycles at the same timing under the same operating condition of the internal combustion engine.   The ignition device according to claim 4, wherein the high-frequency voltage control means performs the sampling control a plurality of times per ignition cycle of the internal combustion engine. An ignition method for igniting an air-fuel mixture in a combustion chamber of an internal combustion engine,
(A) generating a DC pulse;
(B) performing a DC pulse discharge in the combustion chamber based on the DC pulse generated in the step (a);
(C) generating a high frequency voltage;
(D) performing electromagnetic wave radiation in the combustion chamber based on the high-frequency voltage generated in the step (c);
(E) measuring the incident voltage and the reflected reflected voltage incident in the step (d);
(F) controlling the high-frequency voltage generated in the step (c) based on the incident voltage and the reflected voltage measured in the step (e);
With
In the ignition method, the step (f) controls the high-frequency voltage generated in the step (c) based on a ratio of the reflected voltage to the incident voltage.   The ignition method according to claim 7, wherein the step (f) controls sampling of the incident voltage and the reflected voltage measured in the step (e).   9. The ignition method according to claim 8, wherein the step (f) performs the sampling control in an exhaust-intake step of the internal combustion engine.   The ignition method according to claim 8, wherein in the step (f), the sampling is controlled in a compression-explosion step of the internal combustion engine.   11. The ignition method according to claim 10, wherein the step (f) performs a plurality of ignition cycles at the same timing under the same operation conditions of the internal combustion engine in the step (f).   The ignition method according to claim 10, wherein the step (f) performs the sampling control a plurality of times per one ignition cycle of the internal combustion engine.

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