JP5484105B2 - Safety device for spark ignition internal combustion engine - Google Patents

Description

  The present invention relates to a safety device for a spark ignition type internal combustion engine, and more particularly, to a safety device that implements an ignition method in which an induced voltage generated by an ignition coil and a high-frequency electric field generated by an electric field generation circuit are superimposed and applied to an electrode of a spark plug. About.

  In an ignition device mounted on a spark ignition type internal combustion engine, a high voltage generated in the ignition coil when the igniter is extinguished is applied to the center electrode of the ignition plug, whereby the center electrode of the ignition plug and the ground electrode are connected. A spark discharge is caused between and ignited.

  Recently, in order to reliably ignite the air-fuel mixture in the combustion chamber and obtain a stable flame, an electric field generating circuit, in other words, a high frequency voltage output from a high frequency oscillator is applied to the center electrode, An “active ignition” method in which a plasma atmosphere is generated in the space between the center electrode and the ground electrode by the high-frequency electric field and spark ignition is performed in the plasma atmosphere has been attempted (see, for example, the following patent document).

  The electric field generation circuit is an AC voltage generation circuit that generates an AC voltage, a pulsating voltage generation circuit that generates a pulsating voltage, or the like. The high-frequency voltage oscillated by such an electric field generation circuit desirably has a frequency of about 200 kHz to 1000 kHz and an amplitude of about 3 kVp-p to 10 kVp-p.

  Usually, since the electric field generation circuit is disposed in the bonnet, a high frequency originating from the electric field generation circuit is not radiated outside the vehicle body due to electrostatic shielding. However, under the condition that the hood is opened at the time of inspection of an automobile, a high frequency may be radiated out of the vehicle body, which may cause a problem such as a problem with electronic devices existing in the vicinity.

Japanese Patent Application No. 2009-255843

  The present invention has been made by paying attention to the above-mentioned problem for the first time, and is intended to prevent high-frequency radiation from being emitted outside the vehicle body, to comply with radio wave regulations, and to prevent problems caused by leakage high-frequency. The purpose of the period.

In the present invention, an ignition coil that is electrically connected to the ignition plug and applies a high voltage that causes spark discharge, and an ignition coil that is electrically connected to the ignition plug and oscillates a high-frequency voltage to generate a spark discharge . Equipped with an electric field generation circuit that generates a high-frequency electric field in the space between the center electrode and the ground electrode, and generates plasma by generating a high-frequency electric field almost simultaneously with the start of spark discharge or immediately before the start of spark discharge be those associated with causing spark ignition internal combustion engine, the operation detection mechanism for detecting a predetermined operation performed at the time of maintenance of the internal combustion engine, when detecting a predetermined operation via the operation detecting mechanism A safety device including a restraining mechanism that restrains generation of a high-frequency electric field by the electric field generating circuit is configured.

  It is preferable that the operation detection mechanism includes a sensor that detects an operation of opening a member that shields the spark plug, for example, a bonnet, a cylinder head, or the like.

  ADVANTAGE OF THE INVENTION According to this invention, it can suppress that the high frequency originating in an electric field production | generation circuit is radiated | emitted out of a vehicle body, can aim at compliance with radio wave regulations, and can prevent the trouble by leakage high frequency beforehand.

1 is a block diagram showing an ignition device, an electric field generation circuit, and a safety device in an embodiment of the present invention. The circuit diagram of the ignition device in the embodiment. The center longitudinal cross-sectional view of the ignition plug in the embodiment. The figure explaining the specific structure of the electric field generation circuit and safety device in the embodiment. The circuit diagram of the H bridge which is an element of the electric field generation circuit in the embodiment. The figure which shows the example of the sensor for detecting the operation which opens the member which shields a spark plug, and the said member in the same embodiment.

  An embodiment of the present invention will be described with reference to the drawings. First, the ignition device 1 will be described. The ignition device 1 is used for an internal combustion engine mounted on a vehicle or the like. As shown in FIGS. 1 and 2, the ignition device 1 generates an igniter 11 that receives an ignition signal emitted from the electronic control device 3, and a high induced voltage that causes spark ignition when the igniter 11 receives the ignition signal. The ignition coil 12 to be generated and the spark plug 13 that receives the application of the induced voltage generated in the ignition coil 12 are used as elements.

  The igniter 11 is a semiconductor switching element that is integrally incorporated in a coil case that houses the ignition coil 12.

  The ignition coil 12 is mainly composed of a primary coil and a secondary coil. A plug mounting portion for inserting and mounting the spark plug 13 is provided at the lower end portion of the coil case.

  As shown in FIG. 3, the spark plug 13 is a center electrode that performs a spark discharge between a terminal 131 connected to the ignition coil 12 in a state where the spark plug 13 is inserted into the plug mounting portion of the coil case and mounted, and the ground electrode 133. 132, a conductor 134 that connects the center electrode 132 and the terminal 131, a noise reduction member 135 disposed so as to surround the conductor 134, and an insulator 136 that covers and insulates the conductor 134 and the noise reduction member 135. And a housing 137 that supports the insulator 136 from the outside and has a ground electrode 133 attached to the lower end thereof.

  In a ready-made spark plug, a noise reduction resistor is often interposed between the center electrode 132 and the terminal 131. The reason why the spark plug 13 does not have a resistor is to prevent the resistor from attenuating the high-frequency voltage output from the electric field generating circuit 2 and applied to the center electrode 132. The noise reduction member 135 provided instead of the resistor is a substantially cylindrical member formed using, for example, Ni—Zn ferrite. The imaginary component of the complex permeability of the noise reduction member 135 is substantially constant in the frequency band of 2 MHz or less, and increases as the frequency increases in at least the frequency band of 2 MHz to 60 MHz.

  The principle of spark ignition by the ignition device 1 is as follows. When the igniter 11 receives the ignition signal from the electronic control unit 3, the igniter 11 is first ignited and a current flows to the primary side of the ignition coil 12, and the igniter 11 is extinguished at the immediately following ignition timing, and this current is Blocked. Then, a self-induction action occurs, and a high voltage is generated on the primary side. Since the primary side and the secondary side share the magnetic circuit and the magnetic flux, a higher induced voltage is generated on the secondary side. This high induction voltage is applied to the center electrode 132 of the spark plug 13, and a spark discharge is generated between the center electrode 132 and the ground electrode 133.

  In addition, an electric field generation circuit 2 is attached to the ignition device 1, and a high-frequency electric field generated by the electric field generation circuit 2 and a high induction voltage generated by the ignition coil 12 are overlapped to form a terminal 131 of the ignition plug 13, and thus a center electrode 132. It is trying to apply.

  Examples of the electric field generation circuit 2 include an AC voltage generation circuit that applies an AC voltage and a pulsating voltage generation circuit that applies a pulsating voltage. When the pulsating voltage generation circuit is employed, any circuit may be used as long as it generates a DC voltage whose voltage periodically changes, and its waveform may be arbitrary. The pulsating voltage includes a pulse voltage that varies from a reference voltage (which may be 0V) to a constant voltage in a constant cycle, a voltage obtained by half-wave rectifying an AC voltage, a voltage obtained by adding a DC bias to the AC voltage, and the like. The high-frequency voltage oscillated by the electric field generation circuit 2 is desirably about 200 kHz to 1000 kHz and about 3 kVp-p to 10 kVp-p in amplitude.

  In the present embodiment, the electric field generation circuit 2 is a circuit that converts the low-voltage direct current into high-voltage alternating current using the battery 4 as a power source, as shown in FIGS. 4 and 5. The electric field generation circuit 2 includes a DC-DC converter 21 that boosts a battery 4 voltage of about 12 V to 300 V to 500 V, an H-bridge circuit 22 that converts direct current output from the DC-DC converter 21 into alternating current, and an H-bridge circuit. A step-up transformer 23 that boosts the alternating current output from 22 to a higher voltage is used as an element.

  Further, a first diode 24 and a second diode 25 are provided at the output end of the electric field generating circuit 2. The first diode 24 has a cathode connected to the signal line of the secondary winding of the step-up transformer 23 and an anode connected to the mixer 5, which is a node with the ignition coil 12. The second diode 25 has an anode connected to the ground line of the secondary winding of the step-up transformer 23 and a cathode grounded. The first diode 24 and the second diode 25 play a role of blocking the negative high voltage pulse current flowing from the secondary side of the ignition coil 12 at the ignition timing.

  The high-frequency voltage oscillated by the electric field generating circuit 2 is applied to the center electrode 132 of the spark plug 13 almost simultaneously with the start of the spark discharge, immediately before the start of the spark discharge or immediately after the start of the spark discharge. Thereby, a high frequency electric field is formed in the space between the center electrode 132 and the ground electrode 133. Then, plasma is generated by performing a spark discharge in a high-frequency electric field, and this plasma generates a large flame nucleus that starts flame propagation combustion.

  In the above, the flow of electrons due to the spark discharge and the ions and radicals generated by the spark discharge are vibrated and meandered by the influence of the electric field, resulting in a long path length and a dramatic increase in the number of collisions with surrounding water and nitrogen molecules. This is due to the increase. Water molecules and nitrogen molecules that have been struck by ions and radicals become OH radicals and N radicals, and the surrounding gas that has been struck by ions and radicals is also ionized, that is, a plasma state. In addition, the region of ignition of the air-fuel mixture increases and the flame kernel also increases. As a result, the two-dimensional ignition by only the spark discharge is amplified to the three-dimensional ignition, and the combustion rapidly propagates into the combustion chamber and expands at a high combustion speed.

  The main component of noise generated at the time of spark discharge between the center electrode 132 and the ground electrode 133 is approximately in the 60 MHz band. As described above, the imaginary component of the magnetic permeability of the noise reduction member 135 takes a large value in the frequency band to which noise generated during spark discharge belongs, specifically, in the 60 MHz band. Therefore, when the noise derived from the spark discharge passes through the portion surrounded by the noise reduction member 135 in the spark plug 13, the noise reduction member 135 acts on the magnetic field component of the high frequency noise, and most of the noise energy is converted into heat. Converted (permeability loss). In this way, the noise derived from the spark discharge that can cause the electronic control unit 3 and other electrical systems to malfunction is attenuated.

  On the other hand, the frequency band of the high frequency voltage output from the electric field generation circuit 2 is between 200 kHz and 1000 kHz. The imaginary component of the magnetic permeability of the noise reduction member 135 in this frequency band is sufficiently smaller than that in the 60 MHz band. Therefore, the attenuation of the high frequency voltage is small and the generation of the plasma atmosphere is not hindered.

  Therefore, in the present embodiment, the safety device 6 is installed to prevent the high frequency generated from the electric field generation circuit 2 from being unexpectedly emitted outside the vehicle body. As shown in FIG. 1, the safety device 6 has an operation detection mechanism 61 for detecting a predetermined operation performed during maintenance of the internal combustion engine, and an electric field when a predetermined operation is detected via the operation detection mechanism 61. And a restraining mechanism 62 that restrains the generation of the electric field by the generating circuit 2.

  The operation detection mechanism 61 detects an operation that releases high-frequency electrostatic shielding using the electric field generation circuit 2 as a source. Typically, this corresponds to an operation of opening a hood in which the internal combustion engine, the ignition device 1 and the electric field generating circuit 2 and the like are accommodated, and an operation of removing a cylinder head cover covering the cylinder head and the ignition plug 13 of the internal combustion engine. As shown in FIGS. 4 and 6, the operation detection mechanism 61 includes a sensor 611 that detects an operation on a member 7 that shields the spark plug 13, that is, a bonnet, a cylinder head cover, a plug cap, and the like. Examples of the sensor 611 include an optical sensor (such as an active infrared sensor) or a mechanical sensor (such as a limit switch) that senses the position of the member 7, and an optical that senses ambient light that enters from the outside as a result of the operation of the member 7. It is conceivable to use a sensor (photo sensor or the like).

  Further, as shown in FIG. 4, the restraining mechanism 62 can be configured by using a switch 621 that can switch connection / disconnection between the battery 4 and the DC-DC converter 21 of the electric field generation circuit 2. The switch 621 is a semiconductor switching element (power transistor or the like) that is ignited / extinguished upon receiving a control signal from the electronic control device 3, or a mechanical switch (relay) that receives a control signal from the electronic control device 3. Etc.).

  The electronic control unit 3 that is a microcomputer system controls ON / OFF of the switch 621 in accordance with a program. The electronic control unit 3 receives a signal output from the sensor 611 and detects the position of the member 7 such as a bonnet, a cylinder head cover, and a plug cap. The switch 621 is provided on the condition that the member 7 is present at a predetermined position where the spark plug 13 is shielded, that is, the high-frequency electrostatic shielding from the electric field generation circuit 2 is maintained. Is turned on, and the electrical connection between the battery 4 and the DC-DC converter 21 is maintained. On the contrary, when it is detected that the member 7 does not exist at the predetermined position where the spark plug 13 is shielded, the switch 621 is turned off to cut off the power supply from the battery 4 to the electric field DC-DC converter 21. .

  According to the present embodiment, the ignition coil 12 that is electrically connected to the spark plug 13 and applies a high voltage that causes spark discharge, and the electrical connection to the spark plug 13 to generate an electric field in the combustion chamber. An operation detection mechanism 61 for detecting a predetermined operation performed during maintenance of the internal combustion engine, which is associated with the spark ignition internal combustion engine including the electric field generation circuit 2, and the operation detection mechanism 61. Since the safety device 6 including the restraining mechanism 62 that restrains the generation of the electric field by the electric field generation circuit 2 when a predetermined operation is detected, a high frequency originating from the electric field generation circuit 2 is unexpectedly emitted outside the vehicle body. Can be effectively suppressed.

  Since the operation detection mechanism 61 is configured using the sensor 611 that detects an operation of opening the member 7 such as a hood that shields the spark plug 13, the operation detection mechanism 61 can be constructed easily and inexpensively. .

  The present invention is not limited to the embodiment described in detail above. For example, in the above embodiment, the electronic control unit 3 is interposed between the sensor 611 and the switch 621. However, the sensor 611 and the switch 621 are directly connected, and a signal output from the sensor 611 is directly transmitted to the switch 621. It is also possible to take a mode of switching ON / OFF of the switch 621.

  Further, while the stop mechanism 62 is in operation, such as when the bonnet is opened, a high-frequency electric field is not formed around the electrode of the spark plug 13 and a sufficiently large plasma is not generated. In short, the conventional spark ignition (inactive ignition) is performed. Since the internal combustion engine may be operated in this state, while the predetermined operation is detected via the operation detection mechanism 61 or while the stop mechanism 62 is operating, the internal combustion engine in the electronic control unit 3 is operated. It is preferable to automatically change the engine operation control program (calculation logic for required fuel injection amount, idle speed, ignition timing, etc.) to that for inactive ignition.

  In addition, the specific configuration of each unit, the processing procedure, and the like can be variously modified without departing from the spirit of the present invention.

  The present invention can be used for controlling an internal combustion engine mounted on a vehicle or the like.

DESCRIPTION OF SYMBOLS 6 ... Safety device 61 ... Operation detection mechanism 611 ... Sensor 62 ... Stopping mechanism 7 ... Member which shields spark plug

Claims (2)

An ignition coil that is electrically connected to the spark plug to apply a high voltage that causes a spark discharge, and a high- frequency voltage that is electrically connected to the spark plug and oscillates to the center electrode of the spark plug in the combustion chamber A spark ignition type that has an electric field generation circuit that generates a high-frequency electric field in the space between the electrodes and generates plasma by generating a high-frequency electric field almost immediately at the start of spark discharge or immediately before or after the start of spark discharge. A safety device associated with an internal combustion engine,
An operation detection mechanism for detecting a predetermined operation performed during maintenance of the internal combustion engine;
A safety device comprising: a stopping mechanism that stops generation of a high-frequency electric field by the electric field generating circuit when a predetermined operation is detected via the operation detecting mechanism. The safety device according to claim 1, wherein the operation detection mechanism includes a sensor that detects an operation of opening a member that shields the spark plug.

Images