WO2019087799A1

WO2019087799A1 - Engine

Info

Publication number: WO2019087799A1
Application number: PCT/JP2018/038844
Authority: WO
Inventors: 正広古谷; 良一萩原; 武本　徹; 和輝壽
Original assignee: ヤンマー株式会社; 国立大学法人名古屋工業大学
Priority date: 2017-10-30
Filing date: 2018-10-18
Publication date: 2019-05-09
Also published as: EP3705714A1; CN111247331A; EP3705714A4

Abstract

An engine (1) is provided with an ignition device (200). The ignition device (200) is provided with: a central electrode (231); a grounding electrode (232) which is provided corresponding to the central electrode (231) and which is connected to ground (GND); and a potential rise promoting unit (250) disposed between ground (GND) and the grounding electrode (232). According to such a configuration, by raising the potential on the grounding electrode 232 side, an electric field in an electric discharge region formed by the central electrode (231) and the grounding electrode (232) can be strengthened before spark discharge occurs. As a result, the voltage when spark discharge begins can be suppressed, and a deterioration in an electrode unit configured from the central electrode (231) and the grounding electrode (232) can be suppressed.

Description

engine

The present invention relates to an engine provided with an ignition device.

Conventionally, a spark plug is disposed in a combustion chamber of an engine, and a voltage generated by an ignition coil is applied to an electrode portion formed of a center electrode and a ground electrode to cause arc discharge in a discharge region of the electrode portion In general, it is generally known to ignite a mixture supplied to a combustion chamber of an engine.

For example, Patent Document 1 discloses an ignition device provided with a main electrode composed of a main high-voltage electrode and a main ground electrode, and an auxiliary electrode composed of an auxiliary high-voltage electrode and an auxiliary ground electrode. In the igniter of Patent Document 1, the high voltage of the secondary coil connected to the battery is applied to the auxiliary electrode, and the switch is switched after a predetermined time has elapsed to apply the high voltage to the main electrode to generate a spark discharge. .

Further, in Patent Document 2, in the spark discharge generator, a discharge voltage waveform observation terminal is used as one of the discharge electrodes to easily calculate discharge energy by a waveform observation means using an oscilloscope, and a resistor for discharge current waveform observation. The igniter which provides (R3) in the other of the said discharge electrode is disclosed.

JP 2007-032349 A JP, 2005-185027, A

In the conventional igniters disclosed in Patent Documents 1 and 2 described above, the ground electrode is always connected to the ground (GND), and the voltage on the ground electrode side is maintained at approximately 0V. In such a configuration, the voltage of the main electrode or auxiliary electrode required to generate the spark discharge becomes relatively large, the voltage required to generate the spark discharge becomes relatively large, and the spark discharge When generated, a large current flows, and there is a problem that each electrode is easily deteriorated.

In order to solve the above-mentioned main technical problems, according to the present invention, an engine is provided with an ignition device, wherein the ignition device is provided corresponding to a center electrode and the center electrode, and is a ground electrode connected to ground. An engine is provided comprising: and a potential rise promoting portion disposed between the ground and the ground electrode.

The potential rise promoting unit includes a power supply to which the ground electrode provided corresponding to the center electrode is connected via a first switch, and a control unit for causing the ignition device to generate spark discharge. The ground electrode is connected to ground via a second switch, and the control unit turns on the first switch to connect the ground electrode to the power supply in a state where the second switch is turned off. Control is performed to raise the potential of the ground electrode, and after the potential rise control is performed, a voltage is applied between the center electrode and the ground electrode in a state where the potential of the ground electrode is raised. Spark discharge can be generated.

The control unit may turn on the first switch from ON to OFF before generating spark discharge after turning on the first switch to carry out the potential increase control. .

Further, the control unit may be configured to generate spark discharge in a state in which the first switch is turned on to perform the potential increase control.

Furthermore, after generating the spark discharge, the control unit may turn on the second switch for a predetermined time while the first switch is turned off.

The potential rise promoting portion is a response delay generation portion provided between the ground and the ground electrode, provided corresponding to the center electrode, and provided with a ground electrode connected to the ground. Can.

The response delay generation unit includes a winding unit.

The engine further comprises a cylinder head having a mounting hole for mounting a spark plug having the center electrode and the ground electrode, the spark plug having a conductive housing on which the ground electrode is formed, The spark plug may be attached to the attachment hole via an insulator, and the housing and the cylinder head may be configured to be connected via the response delay generation unit. The response delay generation unit may be formed as a gasket when attaching the spark plug to the attachment hole.

The engine further includes a cylinder head having a mounting hole for mounting a spark plug having the center electrode and the ground electrode, and the response delay generation unit includes a resistor, the resistor, and the cylinder head. And a winding portion disposed between the two, wherein the spark plug has a conductive housing on which the ground electrode is formed, and is configured to be attached to the attachment hole via the resistor. It may be done.

The engine further includes a cylinder head having a mounting hole for mounting a spark plug having the center electrode and the ground electrode, and the spark plug having the center electrode and the ground electrode is formed with the ground electrode. And the response delay generation unit may be configured to be disposed between the housing and the mounting hole.

The engine further includes a cylinder head having a mounting hole for mounting a spark plug having the center electrode and the ground electrode, and the spark plug is electrically conductive on which the ground electrode is formed and mounted in the mounting hole. The ground electrode may be configured to be connected to the housing via the response delay generator.

The engine further comprises a cylinder head having a mounting hole for mounting a spark plug having the center electrode and the ground electrode, the spark plug having a housing insulated from the center electrode and the ground electrode. It may be attached to the attachment hole via the housing, and the terminal of the ground electrode and the cylinder head may be configured to be connected via the response delay generation unit.

The engine of the present invention comprises an igniter. The igniter includes a center electrode, a ground electrode provided corresponding to the center electrode, connected to the ground, and a potential rise promoting portion disposed between the ground and the ground electrode. According to such a configuration, by raising the potential on the ground electrode side, the electric field in the discharge region formed by the center electrode and the ground electrode can be strengthened before spark discharge occurs. As a result, it is possible to suppress the voltage at the start of the spark discharge, and it is possible to suppress the deterioration of the electrode portion formed of the center electrode and the ground electrode.

The potential rise promotion part of the engine of the present invention can be provided with a power supply and a control part. A ground electrode provided corresponding to the center electrode is connected to the power supply via a first switch. The ground electrode is connected to ground via a second switch. The control unit turns on the ground electrode connected to the ground via the second switch and the first switch in a state where the second switch is turned off to connect the ground electrode to the power supply and the potential of the ground electrode After the potential rise control is performed, a voltage is applied between the center electrode and the ground electrode in a state where the potential of the ground electrode is raised to generate a spark discharge. According to such a configuration, the electric field in the discharge region formed by the center electrode and the ground electrode can be strengthened before spark discharge occurs. As a result, it is possible to suppress the deterioration of the electrode portion formed of the center electrode and the ground electrode.

The potential rise promoting portion of the engine of the present invention can include a center electrode, a ground electrode, and a response delay generating portion. The ground electrode is provided corresponding to the center electrode and connected to ground. The response delay generation unit is provided between the ground and the ground electrode. Thus, the electric field in the discharge area formed by the center electrode and the ground electrode can be strengthened before spark ignition, and the voltage for generating the spark can be lowered. As a result, it is possible to suppress the deterioration of the electrode portion formed of the center electrode and the ground electrode. Further, since the electric field of the electrode portion before the spark discharge is strengthened, the formation of the initial flame kernel when igniting the mixture is promoted, and the combustion period can be shortened.

FIG. 1 is a schematic view of an engine according to a first embodiment of the present invention. It is a block diagram which shows schematic structure of the ignition device arrange | positioned by the engine shown in FIG. It is a time chart which shows change of the secondary voltage in the ignition control of a 1st example, the 1st switch, and the 2nd switch. It is a time chart which shows change of the secondary voltage in the ignition control of the 2nd example, the 1st switch, and the 2nd switch. It is a figure which shows the pressure change history at the time of igniting air-fuel mixture about each of 1st Example, 2nd Example, and a prior art. It is a schematic diagram of the engine provided with the ignition device which concerns on 3rd Example. It is a block diagram which shows schematic structure of the ignition device arrange | positioned by the engine shown in FIG. It is a figure which shows the example of a circuit of the response delay production | generation part of the ignition device shown in FIG. It is a time chart which shows the center electrode side voltage at the time of performing ignition control by the igniter of conventional and each example, a ground electrode side voltage, and current. It is a figure which shows the spark plug and the other Example of the attachment structure of a spark plug. It is a figure which shows the pressure change history at the time of igniting air-fuel mixture by 3rd Example and a prior art.

Hereinafter, a first embodiment of an engine configured based on the present invention will be described in detail with reference to the attached drawings.

(First embodiment)
FIG. 1 schematically shows the configuration of the engine 100 in which the igniter 200 is disposed. The gas engine 100 is, for example, an engine fueled by city gas supplied from a pipeline. The engine 100 is an engine of a type in which a mixture of fuel gas G and air is supplied to a combustion chamber M described later, and ignition is performed by an ignition plug 230.

The engine 100 includes an engine body 10, an intake system 20, an exhaust system 30, and an ignition device 200 including an ECU (Engine Control Unit) 50 as a control unit and an ignition plug 230. The spark plug 230 has a center electrode 231 and a ground electrode 232.

The engine main body 10 includes a cylinder head 70, a cylinder block 80, and the like. The engine body 10 includes a plurality of cylinders 11. In FIG. 1, only one of the plurality of cylinders 11 is shown. The cylinders 11 are communicated by an intake system 20 and communicated by an exhaust system 30. The intake system 20 includes an intake port 21 formed in the cylinder head 70 and an intake manifold 22. The exhaust system 30 includes an exhaust port exhaust port 31 and an exhaust manifold 32.

A gas injector 42 is provided in the intake manifold 22. On the upstream side of the intake system 20, an intercooler, a main throttle, a compressor of a supercharger, and the like (not shown) are disposed. On the downstream side of the exhaust manifold 32 in the exhaust system 30, a turbine or the like (not shown) of a turbocharger is disposed.

The ECU 50 performs the ignition control described later on the ignition device 200, and controls the main throttle etc. so that the intake manifold pressure as the air flow rate becomes the target intake manifold pressure. Control the whole.

The configuration of the cylinder head 70 will be further described with reference to FIG.

The cylinder head 70 is disposed on the top of the cylinder block 80. The cylinder head 70 is provided with an intake valve 71, an exhaust valve 72, and an ignition plug 230 facing a combustion chamber M described later.

A piston P is slidably accommodated in the cylinder 12 of the cylinder 11. A combustion chamber M is formed by the inner wall of the cylinder 12 of the cylinder 11, the lower surface of the cylinder head 70, and the top of the piston P.

A fuel supply pipe 41 is connected to the intake manifold 22 via a gas injector 42 and an intake manifold pressure sensor 54 is disposed. A fuel gas pressure sensor 55 for detecting a fuel gas pressure and a fuel gas pressure regulator 56 are disposed in the fuel supply pipe 41.

The engine 100 is further provided with an engine speed sensor 51 for detecting an engine speed Ne and an engine output sensor 52 for detecting an engine output W. The engine speed sensor 51 and the engine output sensor 52 are connected to the ECU 50 together with the gas injector 42, the fuel gas pressure sensor 55, and the fuel gas pressure regulator 56. The ECU 50 is not limited to the above-described sensor and device, and various sensors and devices may be connected.

In the ECU 50, a fuel injection amount map is set. The fuel injection amount map represents the correlation between the engine rotational speed Ne, the engine output W, and the command fuel injection amount Q as the fuel flow rate, and the command fuel injection with respect to the engine rotational speed Ne and the engine output W It determines the quantity Q. The ECU 50 controls the gas injector 42 based on the command fuel injection amount Q.

Further, a target intake manifold pressure map is set in the ECU 50. The target intake manifold pressure map represents the correlation between the engine rotational speed Ne, the engine output W, and the target intake manifold pressure Pi, and the target intake manifold pressure Pi is calculated relative to the engine rotational speed Ne and the engine output W. It is decided. The ECU 50 controls the main throttle so that the intake manifold pressure becomes the target intake manifold pressure Pi.

With the above configuration, the ECU 50 controls the fuel gas pressure regulator 56, the gas injector 42, the main throttle, etc., and supplies the mixed gas of the fuel gas G and the air to the intake manifold 22. . The mixed gas is supplied to the combustion chamber M via the intake manifold 22 and ignited by the spark plug 230.

The ignition device 200 will be further described with reference to FIG. 2 in addition to FIG.

The ignition device 200 is configured to include the ECU 50 described above and the spark plug 230.
The spark plug 230 is disposed in the cylinder 11.

As shown in FIG. 2, the igniter 200 includes an ignition coil including a primary coil 241, a secondary coil 242, and a core 243, and an igniter 244. The primary coil 241 is wound around the core 243. One end of the primary coil 241 is connected to the power supply 245, and the other end of the primary coil 241 is connected to the igniter 244. The secondary coil 242 is wound around the core 243. One end of the secondary coil 242 is connected to the primary coil 241, and the other end of the secondary coil 242 is connected to the terminal 231 a of the center electrode 231.

The igniter 244 is, for example, a transistor, and switches between supply and stop of power from the power supply 245 to the primary coil 241 in response to the energization signal from the ECU 50 described above. The high voltage application unit 240 described above is a circuit generally known as a circuit for applying a voltage to the spark plug, and various modifications can be assumed. For example, in the present embodiment, the igniter 244 is formed of a transistor, but is not limited to this, and it may be replaced by a point (contact) type distributor or the like.

The igniter 200 further includes a power source 251, a first switch 252, and a second switch 253. The ground electrode 232 of the spark plug 200 is connected to the power supply 251 via the first switch 252. The first switch 252 connects and disconnects the power supply 251 and the ground electrode 232. The ground electrode 232 is connected to GND via the second switch 253. The second switch 253 connects and disconnects the ground electrode 232 and GND. Preferably, the first switch 252 and the second switch 253 are capable of high speed response and correspond to high voltage. The first switch 252 and the second switch 253 operate in response to an instruction signal from the ECU 50, and are controlled at predetermined timings. The power supply 251 is connected via the first switch 252 to the ground electrode 232 provided corresponding to the center electrode 231 described above, and the ECU 50 provided as a control unit for causing the ignition device 200 to generate spark discharge. A potential rise promoting portion is configured. By raising the potential on the ground electrode side by this potential rise promoting portion, the electric field of the discharge region formed by the center electrode and the ground electrode can be strengthened before spark discharge occurs.

As shown in FIG. 1, the spark plug 230 is provided with a threaded portion 233. The screw portion 233 is used to attach the spark plug 230 to the attachment hole 73 formed in the cylinder head 70.

The ignition control implemented in the above-described igniter 200 will be described below with reference to FIG. 3 (a) shows the change of the secondary voltage from the ignition coil, FIG. 3 (b) shows the ON / OFF state of the first switch 252, and FIG. 3 (c) shows the second switch 253. Indicates the ON / OFF state of the.

When spark discharge is generated by the spark plug 230, the ECU 50 performs control of increasing the potential of the ground electrode 232. Specifically, first, as shown in FIG. 3B, with the second switch 253 turned off, the first switch 252 of the ground electrode voltage application unit 250 is set to a predetermined value by an instruction signal from the ECU 50. Turn on time. Thereafter, the first switch 252 is turned OFF before applying a voltage to the spark plug 230 for spark discharge (see FIG. 3B). In this manner, the potential increase control for the ground electrode 232 is performed, and the state in which the electric field formed by the center electrode 231 and the ground electrode 232 is strengthened is maintained.

In parallel to the above-described potential increase control, an energization signal is sent from the ECU 50 to the igniter 244 at a timing taking into consideration the ignition timing determined by the operating state of the engine. As a result, current is supplied from the power source 245 to the primary coil 241 to form a magnetic field around the core 243. As described above, even after the first switch 252 is turned off, the state in which the electric field formed by the center electrode 231 and the ground electrode 232 is strengthened continues. In this state, the ECU 50 turns off the energization signal to the igniter 244. As a result, the energization of the primary coil 241 from the power supply 245 is stopped. By stopping energization of the primary coil 241, an electromotive force is generated on the secondary coil 242 side due to the mutual induction action, and a negative secondary voltage is generated as shown in FIG. 3 (a). The timing at which this secondary voltage occurs is indicated by ST in FIG. Then, a voltage is applied to the discharge region formed between the center electrode 231 and the ground electrode 232 by this secondary voltage, and spark discharge occurs at the timing shown by BD in FIG. 3 and compressed in the combustion chamber M. The mixture is ignited. After the spark discharge occurs, the ground electrode 232 is connected to GND by turning on the second switch 253 for a predetermined time (see FIG. 3C), and the potential of the ground electrode 232 is in the initial state (0 V). ). The time to turn on the second switch 253 is stored in advance in the ECU 50, for example. Although not particularly limited, the time for turning on the second switch 253 can be 1 to 10 msec. Such ignition control is repeatedly performed according to the ignition timing of each cylinder 11.

In the present embodiment, before the spark discharge is caused by the spark plug 230, potential increase control for raising the potential of the ground electrode 232 is performed in advance, and the discharge region formed between the center electrode 231 and the ground electrode 232 is The electric field is enhanced. As a result, the secondary voltage for causing spark discharge in the spark plug 230 can be reduced compared to the prior art, and as a result, deterioration of the center electrode 231 and the ground electrode 232 can be suppressed. Become.

The present invention is not limited to the configuration shown in the first embodiment described above, and various modifications can be assumed. The second embodiment will be described below.

Second Embodiment
The second embodiment is similar to the first embodiment in that the configurations of the engine 100 and the ignition device 200 shown in FIGS. 1 and 2 are used, and the description of the common points is omitted. The second embodiment differs from the first embodiment in the timing of an instruction signal from the ECU 50 for the first switch 252 and the second switch 253. Here, differences from the first embodiment will be mainly described with reference to FIGS. 2 and 4.

In the second embodiment, when applying a high voltage to the spark plug 230, first, the first switch 252 is turned ON by an instruction signal from the ECU 50, and the ON state is maintained to increase the potential of the ground electrode 232. The potential rise control to maintain is implemented (refer FIG.4 (b)). At this time, the second switch 253 is in the OFF state. As a result, the electric field in the discharge region formed by the center electrode 231 and the ground electrode 232 is further strengthened than in the first embodiment.

In a state in which the electric field formed by the center electrode 231 and the ground electrode 232 is strengthened, an energization signal is sent from the ECU 50 to the igniter 244. The ECU 50 transmits an energization signal to the igniter 244 at a timing taking into consideration the ignition timing determined by the operating state of the engine. When an energization signal is sent from the ECU 50 to the igniter 244, a current is supplied from the power source 245 to the primary coil 241 to form a magnetic field around the core 243. Then, after a predetermined time has elapsed, the ECU 50 turns off the energization signal to the igniter 244 at the timing indicated by ST in FIG. 4. As a result, the energization of the primary coil 241 from the power supply 245 is stopped. By stopping energization of the primary coil 241, an electromotive force is generated on the secondary coil 242 side due to the mutual induction action, and as shown in FIG. 4A, a secondary voltage of negative polarity is generated. Then, spark discharge occurs in the discharge region formed between the center electrode 231 and the ground electrode 232 by the secondary voltage at the timing indicated by BD in FIG. 4, and the air-fuel mixture compressed in the combustion chamber M is ignited. Then, after spark discharge occurs, the first switch 252 is turned off and the second switch 253 is turned on for a predetermined time to connect the ground electrode 232 to the ground, thereby setting the potential of the ground electrode 232 in the initial state 0V). In the present embodiment, the second switch 253 is turned on at the same time as the first switch 252 is turned off, but after the first switch 252 is turned off, the second switch 253 may be turned on. . That is, in a state where the first switch 252 is turned off, the second switch 253 may be turned on for a predetermined time.

Also in the second embodiment, as in the first embodiment, before the spark discharge is caused by the spark plug 230, a control for raising the potential of the ground electrode 232 is performed in advance, and the center electrode 231 and the ground electrode 232 The electric field of the discharge area formed between the two is strengthened. Furthermore, in the second embodiment, the ON state of the first switch 252 is maintained with the timing of generating the spark discharge, so that the potential of the ground electrode 232 is maintained high even after the spark discharge, and the discharge region The electric field of is maintained in a more reinforced state. Therefore, the secondary voltage for causing spark discharge in spark plug 230 can be further reduced compared to the prior art, and as a result, deterioration of center electrode 231 and ground electrode 232 can be suppressed. .

The influence exerted on the pressure change history in the combustion chamber M when the mixture is ignited by the igniter 200 will be described based on FIG. The data shown in FIG. 5 shows the pressure change history in the container when a closed container having a predetermined volume is filled with a mixture of equivalence ratio 0.7 and the container is ignited with the internal pressure at 1 MPa. It is. The dotted line in the drawing shows the pressure change history in the container when spark discharge is caused by the conventional igniter (conventional example) in which the potential increase control is not performed. The solid line indicates the pressure change history in the container when spark discharge is caused by the ignition control of the first embodiment described above, and the dashed line indicates the inside of the container when spark discharge is caused by the ignition control of the second embodiment. Shows the pressure change history of In addition, in FIG. 5, the ignition timing (0 ms) which spark discharge produced is arrange | equalized, and the pressure change history in the container after that is compared.

As understood from FIG. 5, according to the ignition control of the first embodiment shown by the solid line, the pressure rise after the spark discharge can be quickened as compared with the prior art. This is because the electric field between the center electrode 231 and the ground electrode 232 is strengthened before the spark discharge is generated, and the electric field is maintained in an enhanced state as the mixture is ignited and combustion proceeds. This indicates that the formation of initial flame nuclei was promoted, the combustion of the mixture progressed favorably, and the combustion period was shortened.

According to the ignition control of the second embodiment indicated by the alternate long and short dash line, the pressure increase is further accelerated and the combustion period is further shortened compared to the first embodiment. This is because, in the ignition control of the second embodiment, the ON state of the first switch 252 is maintained from before the spark discharge occurs to after the spark discharge, and the electric field in the discharge region during the spark discharge and in the subsequent combustion period is more It is guessed that it is because it was strengthened.

Hereinafter, a third embodiment of an engine equipped with an ignition device will be described in detail with reference to the attached drawings.

Third Embodiment
In FIG. 6, the structure of the engine 100 provided with the ignition device 200 which concerns on a present Example is shown typically. The engine 100 is, for example, an engine that uses city gas supplied from a pipeline as a fuel, and supplies an air-fuel mixture of fuel gas G and air to a combustion chamber M described later and ignites it with an ignition plug 230 It is.

Engine 100 includes an engine body 10, an intake system 20, an exhaust system 30, an ECU (Engine Control Unit) 50 as a control unit, and an ignition device 200 including an ignition plug 230 and a response delay generation unit 260. Have. The spark plug 230 has a center electrode 231 and a ground electrode 232.

The engine main body 10 includes a cylinder head 70, a cylinder block 80, and the like. The engine body 10 includes a plurality of cylinders 11. Only one of the plurality of cylinders 11 is shown in FIG. The cylinders 11 are communicated by an intake system 20 and communicated by an exhaust system 30. The intake system 20 includes an intake port 21 formed in the cylinder head 70 and an intake manifold 22. The exhaust system 30 includes an exhaust port 31 and an exhaust manifold 32.

The ECU 50 performs ignition control of the ignition device 200, and controls the main throttle and the like so that the intake manifold pressure as the air flow rate becomes the target intake manifold pressure.

The cylinder head 70 is disposed on the top of the cylinder block 80. The cylinder head 70 is provided with an intake valve 71, an exhaust valve 72, and an ignition plug 230 facing a combustion chamber M described later. The cylinder head 70 has a mounting hole 73 for mounting the spark plug 230 on the cylinder head 70.

A piston P is slidably accommodated in the cylinder 12 of the cylinder 11. In the cylinder head 70, a combustion chamber M is formed by the inner wall of the cylinder 12 of the cylinder 11, the lower surface of the cylinder head 70, and the top of the piston P.

A fuel supply pipe 41 is connected to the intake manifold 22 via a gas injector 42, and an intake manifold pressure sensor 54 is disposed. A fuel gas pressure sensor 55 for detecting a fuel gas pressure and a fuel gas pressure regulator 56 are disposed in the fuel supply pipe 41.

Further, a target intake manifold pressure map is set in the ECU 50. The target intake manifold pressure map represents the correlation between the engine rotational speed Ne, the engine output W, and the target intake manifold pressure Pi, and determines the target intake manifold pressure Pi with respect to the engine rotational speed Ne and the engine output W It is The ECU 50 controls the main throttle so that the intake manifold pressure becomes the target intake manifold pressure Pi.

With the above configuration, the ECU 50 controls the fuel gas pressure regulator 56, the gas injector 42, the main throttle, and the like to supply the air-fuel mixture obtained by mixing the fuel gas G and air to the intake manifold 22. . The mixed gas is supplied to the combustion chamber M via the intake manifold 22 and ignited by the spark plug 230.

The ignition device 200 will be further described with reference to FIGS. 7 and 8 in addition to FIG.

The ignition device 200 is configured to include the ECU 50 described above, the spark plug 230, and the response delay generation unit 260 that functions as a potential increase promotion unit in the present embodiment. As schematically shown in FIGS. 6 and 7, the ignition device 200 generates a spark discharge between the center electrode 231 and the ground electrode 232 through the terminal 231a connected to the center electrode 231 of the spark plug 230. Apply a voltage to make it The response delay generation unit 260 is disposed between the ground electrode 232 and GND. The response delay generation unit 260 maintains the potential of the ground electrode 232 in a high state before spark discharge, and the potential of the ground electrode 232 in order to strengthen the electric field of the discharge region formed between the center electrode 231 and the ground electrode 232. It has the function of causing a response delay to changes. The electric field in the discharge area formed by the center electrode and the ground electrode is strengthened before spark discharge occurs by raising the electric potential on the ground electrode side by the response delay acceleration unit 260 functioning as the electric potential rise promotion portion. Can.

As shown in FIG. 7, the igniter 200 includes an ignition coil composed of a primary coil 241, a secondary coil 242, and a core 243, an igniter 244, and a power source 245. The primary coil 241 is wound around the core 243. One end of the primary coil 241 is connected to the power supply 245, and the other end of the primary coil 241 is connected to the igniter 244. The secondary coil 242 is wound around the core 243. One end of the secondary coil 242 is connected to the primary coil 241, and the other end of the secondary coil 242 is connected to the terminal 231 a of the center electrode 231 of the spark plug 230.

The igniter 244 is composed of, for example, a transistor. The igniter 244 switches between supply and stop of the power from the power source 245 to the primary coil 241 in response to the above-described energization signal from the ECU 50. The circuit described above is a circuit generally known as a circuit for applying a voltage to the spark plug, and various modifications can be assumed. For example, in the present embodiment, the igniter 244 is configured by a transistor, but the present invention is not limited to this, and a point (contact) type distributor (divider) or the like can be replaced.

The response delay generation unit 260 is disposed between the ground electrode 232 of the spark plug 230 and GND, as shown in FIG. The response delay generation unit 260 has a function of preventing the potential of the ground electrode 232 from being lowered after spark discharge occurs in the discharge region formed between the center electrode 231 and the ground electrode 232. The response delay generation unit 260 preferably includes a winding unit (coil). The response delay generation unit 260 generates an electromotive force by the transient response due to the provision of the winding portion to realize the above function.

An example of a circuit constituting the response delay generation unit 260 is shown in FIG. As shown in FIG. 8, the response delay generation unit 260 can include an inductor as a winding unit. More specifically, as the configuration of the response delay generation unit 260, a configuration including the inductor 261 (see FIG. 8A), and a configuration in which the resistor 262 and the inductor 263 are disposed in series (FIG. b) or the resistor 264 and the inductor 265 arranged in series, and the configuration including the capacitor 266 arranged in parallel with these (see FIG. 8C), etc. it can. The configuration shown in FIG. 8C can be realized by, for example, a carbon film resistor. A carbon film resistor forms a pure carbon film closely fixed on the surface of a porcelain rod by thermal decomposition in high temperature and high vacuum, and cuts a spiral groove in the carbon film to form a winding structure. By forming it, the required resistance value is obtained. 8 (a) to (c) by adjusting the inductance of the winding part (inductor 261), the resistance values of the

resistors

262 and 264, the capacitance of the capacitor 266, etc. The transient response characteristics of 260 can be adjusted. The transient response characteristic of the response delay generation unit 260 is appropriately determined by experiment or the like. In addition, the ignition plug 230 which comprises the ignition device 200 is arrange | positioned by every cylinder 11. FIG.

Referring back to FIG. 6, the detailed configuration of the spark plug 230 and a configuration example of the response delay generation unit 260 will be described. The center electrode 231 and the ground electrode 232 are disposed at the tip of the spark plug 230. The spark plug 230 further has a conductive housing 234. The center electrode 231 is electrically connected to the upper terminal 231 a through the center of the spark plug 230 and the copper core surrounded by the insulator. The ground electrode 232 is formed in a conductive housing 234. The housing 234 is made of, for example, a special nickel alloy or the like. The housing 234 includes a screw portion 243 a and a head portion 243 b. The screw portion 243 a is coupled to the mounting hole 73 of the cylinder head 70. The ground electrode 232 is engaged with one end of the screw portion 243a. The head portion 243 b is connected to the other end of the screw portion 243 a.

In the present embodiment, a substantially cylindrical insulator 74 is disposed between the mounting hole 73 of the cylinder head 70 and the housing 234 of the spark plug 230. The insulator 74 cuts off electrical conduction between the cylinder head 70 and the spark plug 230. The insulator 74 has a substantially cylindrical shape. The response delay generation unit 260 described above is disposed between the housing 234 of the spark plug 230 and the cylinder head 70. The housing 234 and the cylinder head 70 are connected via the response delay generation unit 260. According to such a configuration, it is not necessary to process the spark plug 230 to form the response delay generation unit 260. Therefore, a commonly used spark plug can be employed as the spark plug 230 of the present embodiment.

The present embodiment is generally configured as described above, and the ignition control performed by the above-described igniter 200 will be described below with reference to FIGS. 6 to 9.

In order to generate spark discharge by the spark plug 230, an energization signal is sent from the ECU 50 to the igniter 244 at a timing taking into consideration the ignition timing determined by the operating state of the engine. As a result, current is supplied from the power source 245 to the primary coil 241 to form a magnetic field around the core 243. Then, the energization signal to the igniter 244 is shut off, whereby the energization of the primary coil 241 from the power supply 245 is stopped. By stopping the energization of the primary coil 241, a secondary voltage of negative polarity is generated on the secondary coil 242 side by mutual induction. Then, a voltage is applied to a discharge region formed between the center electrode 231 and the ground electrode 232 by the secondary voltage, thereby causing spark discharge, and the air-fuel mixture compressed in the combustion chamber M is ignited. Such ignition control is repeatedly performed according to the ignition timing of each cylinder 11.

FIG. 9A is a time chart showing the voltage on the center electrode side, the voltage on the ground electrode side, and the current when ignition control is performed by the conventional ignition device. FIG. 9B is a time chart showing the center electrode side voltage, the ground electrode side voltage, and the current when the ignition control is performed by the ignition device 200 of the present embodiment. In FIG. 9, the timing at which spark discharge occurs is indicated by BD.

In the conventional igniter, the ground electrode is always connected to GND. For this reason, in the conventional ignition device, as shown by the dotted line in FIG. 9A, the ground electrode side voltage is maintained at approximately 0V. In such a configuration, as shown by the solid line in FIG. 9A, the central electrode side voltage required to generate spark discharge becomes larger than the installation electrode side voltage. As a result, as indicated by the alternate long and short dash line in FIG. 9A, a large current flows when spark discharge occurs. Therefore, the center electrode and the ground electrode are easily deteriorated.

On the other hand, in the ignition device 200 of the present embodiment, the response delay generation unit 260 is disposed between the ground electrode 232 and GND. For this reason, after spark discharge occurs and ignition of the air-fuel mixture is performed, as shown by a dotted line in FIG. 9B, the voltage on the ground electrode side does not decrease for a while. That is, the state in which the electric field in the discharge region formed between the center electrode 231 and the ground electrode 232 is strengthened is maintained. By performing the ignition control in such a configuration, as shown by the solid line in FIG. 9, it is possible to lower the center electrode voltage for causing spark discharge in the spark plug 230 as compared with the conventional ignition device. it can. As a result, it is possible to suppress the value of the current flowing at the time of spark discharge, and to suppress the occurrence of deterioration in the center electrode 231 and the ground electrode 232. The response delay generation unit 260 of this embodiment may be configured by any of the circuit examples of the response delay generation unit 260 shown in FIGS. 8A to 8C.

As shown in FIG. 9 (b), in the ignition device 200 of the present embodiment, after spark discharge occurs, the ground electrode side voltage does not drop sharply, but gradually drops. This phenomenon is called response delay. The response delay generation unit 260 is a component for generating the response delay.

The present invention is not limited to the configuration shown in the third embodiment described above, and various modifications can be envisioned as long as they fall within the technical scope of the present invention. Other embodiments will be described below. The other embodiments described below are different from the third embodiment in the mounting structure of the spark plug 230 with respect to the spark plug 230, the response delay generation unit 260, and the mounting hole 73 of the cylinder head 70. Since the configuration is common, the detailed description of the common points is omitted.

Fourth Embodiment
The fourth embodiment will be described with reference to FIG. The fourth embodiment shown in FIG. 10 (a) is configured to realize the circuit example shown in FIG. 8 (b). The response delay generation unit 260 is configured of a resistor 262 and an inductor 261 (winding portion). The resistor 262 is disposed in the mounting hole 73 of the cylinder 70. The resistor 262 has a substantially cylindrical shape. The spark plug 230 is attached to the attachment hole 73 via the resistor 262.

In the fourth embodiment, the response delay generation unit 260 is configured by the inductor 261 and the resistor 262. In this case, it is not necessary to process the spark plug 230 for forming the response delay generation unit 260. Therefore, it is possible to adopt a commonly used spark plug as it is. Further, the resistance value of the resistor 262 can be selected appropriately.

Fifth Embodiment
The fifth embodiment will be described with reference to FIG. In the fifth embodiment shown in FIG. 10B, as in the third embodiment, the spark plug 230 is attached to the attachment hole 73 of the cylinder head 70 via the insulator 74. At that time, a gasket as the response delay generation unit 260 is disposed between the housing 234 of the spark plug 230 and the mounting hole 73 of the cylinder head 70. The response delay generation unit 260 maintains the airtightness between the spark plug 230 and the cylinder head. In the response delay generation unit 260 of the present embodiment, a through hole is formed in the central portion (not shown), and the screw portion 243 a of the spark plug 230 is inserted into the through hole. Thus, the housing 234 of the spark plug 230 and the cylinder head 70 are not directly connected, but are connected via the response delay generation unit 260. The response delay generation unit 260 of the present embodiment can be configured to have, for example, a winding structure and an inductance. With such a configuration, this embodiment can exhibit the same function and effect as those of the above-described third embodiment. Further, in the present embodiment, as in the third and fourth embodiments, the processing of the spark plug 230 for forming the response delay generation unit 260 is not necessary.

Sixth Embodiment
The sixth embodiment will be described with reference to FIG. In the sixth embodiment shown in FIG. 10 (c), the response delay generation unit 260 having a winding portion is formed in a tubular shape. The screw portion 243 a of the spark plug 230 is inserted into the response delay generation unit 260. That is, the spark plug 230 is attached to the attachment hole 73 of the cylinder head 70 via the response delay generation unit 260. With such a configuration, it is possible to achieve the same function and effect as those of the third embodiment described above. Further, in the present embodiment, as in the third to fifth embodiments, processing of the spark plug 230 for forming the response delay generation unit 260 is not necessary.

Seventh Embodiment
The seventh embodiment will be described with reference to FIG. 10 (d). The seventh embodiment shown in FIG. 10D is different from the third to sixth embodiments in the configuration of the ground electrode 232. In the present embodiment, the ground electrode 232 is connected to the housing 234 via the response delay generation unit 260. Such a response delay generation unit 260 can be configured by, for example, a small-sized inductor, and can achieve the same effects as those of the above-described third embodiment.

Eighth embodiment
The eighth embodiment will be described with reference to FIG. In the eighth embodiment shown in FIG. 10 (e), the center electrode 231 and the ground electrode 232 and the housing 234 are electrically insulated. The terminal 231a of the center electrode 231 is connected to the above-described ignition coil, and the terminal 232a of the ground electrode 232 is connected to the cylinder head 70 via the response delay generation unit 260. The spark plug 230 of this embodiment is directly attached to the attachment hole 73 of the cylinder head 70, but the housing 234 and the ground electrode 232 are insulated. Also in the present embodiment, the same effects as those of the above-described third embodiment can be obtained. In the seventh and eighth embodiments described above, since the spark plug 230 is improved, it is not necessary to make a major change to the cylinder head 70.

The influence exerted on the pressure change history in the combustion chamber M when the mixture is ignited by the igniter 200 will be described based on FIG. The data shown in FIG. 11 shows the pressure change history in the container when a closed container having a predetermined volume is filled with a mixture of equivalence ratio 0.7 and the container is ignited with the internal pressure at 1 MPa. It is. The dotted line in the figure shows the pressure change history in the container when the mixture is ignited by the conventional igniter (conventional example) that does not have the response delay generation unit 260. The solid line in the drawing shows the pressure change history in the container when the mixture is ignited by the igniter 200 of the third embodiment described above. In addition, in FIG. 11, the ignition timing (0 ms) which spark discharge produced is arrange | equalized, and the pressure change history after that is compared.

As understood from FIG. 11, in the third embodiment indicated by a solid line, the pressure rise after ignition is quickened as compared with the prior art. This is because the response delay generation unit 260 enhances the electric field between the center electrode 231 and the ground electrode 232. FIG. 11 shows that in the third embodiment, the state in which the electric field is enhanced is maintained even when the mixture is ignited and the combustion proceeds, thereby promoting the formation of the initial flame kernel and the combustion of the mixture. Progressed well, indicating that the combustion period was shortened.

The present invention is not limited to the above-described embodiments, and can include various modifications as long as they are included in the technical scope of the present invention. Although the above-described first to eighth embodiments each show an example applied to a gas engine fueled by city gas supplied from a pipeline, the present invention is not limited to this. For example, for example, The present invention can be applied to any engine as long as it is an engine that ignites fuel by spark discharge, such as CNG and other gas engines using LNG as a fuel, or a gasoline engine.

10: engine body 11: cylinder 20: intake system 21: intake port 22: intake manifold 30: exhaust system 31: exhaust port 32: exhaust manifold 41: fuel supply path 42: gas injector 50: ECU (control unit)
70: cylinder head 80: cylinder block 100: engine 200: igniter 230: spark plug 231: center electrode 232: ground electrode 234: housing 250: ground electrode voltage application unit 251: power source 252: first switch 253: second Switch 260: response

delay generation units

261, 263, 265: inductor (winding portion)
262, 264: Resistor 266: Capacitor

Claims

An engine comprising an ignition device,
The igniter is
With the center electrode,
A ground electrode provided corresponding to the center electrode and connected to the ground, and a potential rise promoting portion disposed between the ground and the ground electrode;
An engine equipped with
The potential rise promoting unit includes a power supply to which the ground electrode provided corresponding to the center electrode is connected via a first switch, and a control unit for causing the ignition device to generate spark discharge.
The ground electrode is connected to ground via a second switch,
The control unit performs potential increase control to turn on the first switch, connect the ground electrode to the power supply, and raise the potential of the ground electrode, with the second switch turned off. The engine according to claim 1, wherein a spark discharge is generated by applying a voltage between the center electrode and the ground electrode in a state where the potential of the ground electrode is raised after performing the potential rise control.
The engine according to claim 2, wherein the control unit turns on the first switch after turning on the first switch to perform the potential increase control, and then turns off the first switch before generating spark discharge. .
The engine according to claim 2, wherein the control unit generates spark discharge in a state in which the first switch is turned on to perform the potential increase control.
5. The engine according to claim 3, wherein the control unit turns on the second switch for a predetermined period of time with the first switch turned off after generating spark discharge.
The potential rise promoting unit is a response delay generation unit provided between the ground and the ground electrode,
The engine according to claim 1, comprising a ground electrode provided corresponding to the center electrode and connected to the ground.
The engine according to claim 6, wherein the response delay generation unit comprises a winding unit.
The engine further comprises a cylinder head having a mounting hole for mounting a spark plug having the center electrode and the ground electrode,
The igniter plug has a conductive housing in which the ground electrode is formed, the igniter plug is attached to the mounting hole via an insulator, and the housing and the cylinder head have the response delay. The engine according to claim 6 or 7, connected via a generation unit.
The engine according to claim 8, wherein the response delay generation unit is formed as a gasket when attaching the spark plug to the mounting hole.
The engine further comprises a cylinder head having a mounting hole for mounting a spark plug having the center electrode and the ground electrode,
The response delay generation unit includes a resistor, and a winding unit disposed between the resistor and the cylinder head.
The engine according to claim 6, wherein the spark plug has a conductive housing in which the ground electrode is formed, and is mounted to the mounting hole via the resistor.
The engine further comprises a cylinder head having a mounting hole for mounting a spark plug having the center electrode and the ground electrode,
A spark plug having the center electrode and the ground electrode has a conductive housing on which the ground electrode is formed,
The engine according to claim 6, wherein the response delay generator is disposed between the housing and the mounting hole.
The engine further comprises a cylinder head having a mounting hole for mounting a spark plug having the center electrode and the ground electrode,
The spark plug has a conductive housing on which the ground electrode is formed and which is attached to the mounting hole.
The engine according to claim 6, wherein the ground electrode is connected to the housing via the response delay generator.
The engine further comprises a cylinder head having a mounting hole for mounting a spark plug having the center electrode and the ground electrode,
The spark plug has a housing insulated from the center electrode and the ground electrode, and is mounted to the mounting hole via the housing.
The engine according to claim 6, wherein the terminal of the ground electrode and the cylinder head are connected via the response delay generation unit.