JP2018135774A - Ignition device - Google Patents

Abstract

A plasma is efficiently supplied to a combustion chamber.
An ignition device 100 includes a fluid supply pipe 120 communicating with a combustion chamber 102, a first electrode provided in the fluid supply pipe 120, a second electrode provided apart from the first electrode, A plasma generation unit having a high-frequency power source that supplies power to one of the first electrode and the second electrode, and an on-off valve 150 provided on the upstream side of the plasma generation unit 130 in the fluid supply pipe 120. . Thereby, fuel can be efficiently ignited in the combustion chamber 102.
[Selection] Figure 1

Description

  The present disclosure relates to an ignition device that ignites fuel supplied to a combustion chamber.

  Technologies have been developed that reduce NOx in exhaust gas and improve fuel efficiency by supplying pre-mixed gas into a cylinder (combustion chamber) constituting an engine and burning it. As a technique for igniting a premixed gas, a plasma generator that generates water vapor plasma and ejects it into a cylinder is disclosed (for example, Patent Document 1). In the technique of Patent Document 1, plasma is ejected into the cylinder in accordance with the ignition of the premixed gas.

  In general, a valve for supplying fluid to the cylinder or stopping the supply is provided in the vicinity of the cylinder. Therefore, in an engine equipped with the plasma generator, a valve is provided at the outlet of the plasma generator.

JP 2005-299440 A

  However, in the configuration in which the opening / closing valve is provided at the outlet of the plasma generator, the distance from the plasma generation source to the cylinder is long, so that the plasma is attenuated before reaching the cylinder and the ignition performance is deteriorated. is there.

  Therefore, it is conceivable that a coil is wound around an electrode rod (metal core) constituting the plasma generator so that the plasma generator itself functions as a needle valve. However, the voltage applied to the coil for opening and closing the flow path becomes noise of the voltage applied to the electrode rod for generating plasma, and the plasma cannot be generated stably. Alternatively, the voltage applied to the electrode rod in order to generate plasma becomes noise of the voltage applied to the coil to open and close the flow path, resulting in a failure in opening and closing the flow path.

  The present disclosure has been made in view of such a problem, and an object thereof is to provide an ignition device capable of efficiently supplying plasma to a combustion chamber.

  In order to solve the above problem, an ignition device according to an aspect of the present disclosure includes a fluid supply pipe that communicates with a combustion chamber, a first electrode provided in the fluid supply pipe, and the first electrode. A plasma generator having a second electrode provided, and a high-frequency power source for supplying power to one of the first electrode and the second electrode, and provided upstream of the plasma generator in the fluid supply pipe An open / close valve.

  The fluid passing through the fluid supply pipe may be a liquid.

  In addition, the fluid supply pipe includes an enclosure portion that surrounds the first electrode while maintaining a predetermined separation interval, and an opening portion that is provided continuously to the enclosure portion and that opens to the combustion chamber. A reduced diameter portion having a smaller channel cross-sectional area than the portion.

  Moreover, you may provide the cooling part which cools any one or both of the part which surrounds at least one part of the said 1st electrode among the said fluid supply pipe | tubes, and the said 1st electrode.

  The ignition device according to the present disclosure can efficiently supply plasma to the combustion chamber.

It is a figure explaining the ignition device concerning an embodiment. It is a figure explaining the specific structure of a plasma generation part.

  Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiment are merely examples for facilitating understanding, and do not limit the present disclosure unless otherwise specified. In the present specification and drawings, elements having substantially the same functions and configurations are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present disclosure are not illustrated. To do.

  FIG. 1 is a diagram illustrating an ignition device 100 according to the present embodiment. In FIG. 1, the signal flow is indicated by broken lines. The ignition device 100 ignites fuel (for example, premixed gas) supplied to the combustion chamber 102 that constitutes the engine. The engine is, for example, a uniflow scavenging two-cycle engine.

  The ignition device 100 includes a tank 110, a fluid supply pipe 120, a plasma generation unit 130, a cooling unit 140, an on-off valve 150, a pump 160, and a control unit 170.

  The tank 110 stores a liquid containing water. The liquid containing water is, for example, EGR piping or drainage drain (condensed water mixed with fuel or engine oil) generated in the exhaust pipe.

  The fluid supply pipe 120 is a pipe that allows the tank 110 and the combustion chamber 102 to communicate with each other, and allows liquid to pass therethrough.

  The plasma generator 130 generates plasma in the liquid that passes through the fluid supply pipe 120. FIG. 2 is a diagram for explaining a specific configuration of the plasma generator 130. As shown in FIG. 2, the plasma generator 130 includes a first electrode 132, a second electrode 134, and a high frequency power source 136.

  The first electrode 132 is made of metal and includes a main body 132a and a pointed end 132b. The main body 132a has a cylindrical shape. The tip end portion 132b has a proximal end continuous from the main body 132a and gradually decreases in diameter from the proximal end toward the distal end.

  The first electrode 132 is provided in the fluid supply pipe 120. Specifically, in the first electrode 132, the fluid supply pipe 120a surrounding the main body 132a is formed of an insulator. Further, the tip portion 132b is surrounded by a fluid supply pipe 120b made of metal that functions as the second electrode 134.

  The second electrode 134 is a grounded electrode. In the present embodiment, the second electrode 134 is provided on the wall portion 102 a constituting the combustion chamber 102. Further, as described above, the second electrode 134 also functions as the fluid supply pipe 120b, and surrounds the tip end portion 132b while maintaining a predetermined separation interval.

  More specifically, the second electrode 134 has a surrounding part 134a and a reduced diameter part 134b. The surrounding portion 134a surrounds the tip portion 132b while maintaining a predetermined separation interval. In other words, the first hole 134aa is formed in the surrounding part 134a, and the pointed end part 132b is disposed in the first hole 134aa. The diameter of the first hole 134aa gradually decreases from the end communicating with the fluid supply pipe 120a toward the end communicating with the second hole 134ba.

  The reduced diameter portion 134 b is provided continuously with the surrounding portion 134 a and has an opening 134 bb that opens into the combustion chamber 102. In other words, a second hole 134ba that is continuous from the first hole 134aa to the opening 134bb is formed in the reduced diameter portion 134b. The second hole 134ba has a constant channel cross-sectional area, and the channel cross-sectional area is smaller than that of the first hole 134aa.

  The high frequency power source 136 supplies power to the first electrode 132 and applies a pulse voltage based on a control command from the control unit 170 described later. When the high-frequency power source 136 applies a pulse voltage to the first electrode 132, water (liquid) plasma is formed between the tip portion 132b and the surrounding portion 134a, that is, in the first hole 134aa. The water plasma thus formed is supplied to the combustion chamber 102 through the reduced diameter portion 134b. Thereby, the fuel in the combustion chamber 102 can be ignited.

  Further, the liquid plasma has a longer plasma maintenance time than the gas plasma. Therefore, it is possible to reach the combustion chamber 102 without attenuating the plasma.

  Further, since the second hole 134ba formed in the reduced diameter portion 134b has a smaller channel cross-sectional area than the first hole 134aa formed in the surrounding portion 134a, the plasma flow rate can be increased. Thereby, in the combustion chamber 102, plasma can be diffused in a wide range, and the ignition efficiency can be improved.

  The cooling unit 140 is configured by, for example, a water cooling device, and includes a first refrigerant channel 142 and a second refrigerant channel 144. The first refrigerant channel 142 has an inlet and an outlet and is formed in the wall portion of the fluid supply pipe 120a. The second refrigerant channel 144 has an inlet 144 a and an outlet 144 b and is formed inside the first electrode 132. A refrigerant is supplied from an unillustrated refrigerant supply unit to the inlet of the first refrigerant channel 142 and the inlet 144a of the second refrigerant channel 144. Then, the refrigerant passes through the first refrigerant flow path 142, is discharged from the discharge port, passes through the second refrigerant flow path 144, and is then discharged from the discharge port 144b. Thereby, the fluid supply pipe 120a and the first electrode 132 can be cooled. Therefore, it is possible to avoid a situation where water evaporates due to heat generated by applying a voltage to the first electrode 132.

  Returning to FIG. 1, the on-off valve 150 is provided between the tank 110 and the plasma generator 130 in the fluid supply pipe 120 (upstream of the plasma generator 130). With this configuration, it is possible to shorten the distance from the plasma generation source to the combustion chamber 102 as compared with the conventional technique in which an opening / closing valve is provided at the outlet of the plasma generation unit 130. Therefore, it is possible to suppress the attenuation of the plasma and to suppress the deterioration of the ignition performance.

  Further, unlike the configuration in which the plasma generator 130 itself functions as a needle valve, the plasma generator 130 can be applied without applying an unnecessary voltage other than the voltage for generating plasma to the first electrode 132 and the second electrode 134. The liquid can be supplied to or stopped from the liquid. Therefore, it is possible to avoid a situation in which noise is generated in the voltage applied to the first electrode 132, and to stably generate plasma.

  The pump 160 is provided between the tank 110 and the on-off valve 150 in the fluid supply pipe 120. The pump 160 pumps the liquid stored in the tank 110 to the fluid supply pipe 120.

  The control unit 170 is, for example, an ECU (Engine Control Unit), and includes a semiconductor integrated circuit including a CPU (Central Processing Unit). The control unit 170 reads programs, parameters, and the like for operating the CPU itself from the ROM, and manages and controls the entire ignition device 100 in cooperation with the RAM as a work area and other electronic circuits.

  In the present embodiment, the control unit 170 controls the high frequency power source 136, the on-off valve 150, and the pump 160. More specifically, the control unit 170 controls the high-frequency power source 136, the on-off valve 150, and the pump 160 so that water plasma is supplied to the combustion chamber 102 at the fuel ignition timing based on the crank angle of the engine.

  As described above, according to the ignition device 100 according to the present embodiment, it is possible to efficiently supply plasma to the combustion chamber.

  As mentioned above, although embodiment was described referring an accompanying drawing, it cannot be overemphasized that this indication is not limited to this embodiment. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims and that they naturally fall within the technical scope.

  For example, in the above-described embodiment, the liquid that passes through the fluid supply pipe 120 has been described by taking a liquid containing water as an example. However, the fluid may be a gas (eg, water vapor).

  In the above-described embodiment, the configuration in which the second electrode 134 includes the reduced diameter portion 134b has been described as an example. However, the reduced diameter portion 134b is not an essential configuration.

  Moreover, in the said embodiment, the structure which the 1st electrode 132 was provided with the pointed part 132b was mentioned as an example, and was demonstrated. However, the tip portion 132b is not an essential configuration. That is, the 1st electrode 132 may be comprised with the cylinder of the same diameter.

  In the above embodiment, the configuration in which the second electrode 134 also functions as the fluid supply pipe 120 has been described as an example. However, the second electrode 134 may be configured separately from the fluid supply pipe 120.

  Moreover, in the said embodiment, the cooling unit 140 demonstrated and demonstrated the structure which cools the fluid supply pipe | tube 120a and the 1st electrode 132 as an example. However, the cooling unit 140 only needs to be able to cool either one or both of the fluid supply pipe 120 that surrounds at least a part of the first electrode 132 and the first electrode 132. For example, the cooling unit 140 may cool the second electrode 134.

  In addition, the case where the cooling unit 140 is configured by a water cooling device has been described as an example. However, the cooling unit 140 is limited to the configuration as long as one or both of the first electrode 132 and the fluid supply pipe 120 surrounding at least a part of the first electrode 132 can be cooled. There is no. For example, the cooling unit 140 may be configured by an air cooling device or a Peltier element.

  The present disclosure can be used for an ignition device that ignites fuel supplied to a combustion chamber.

100 ignition device 120 fluid supply pipe 120a fluid supply pipe 120b fluid supply pipe 130 plasma generating part 132 first electrode 134 second electrode 134a surrounding part 134b reduced diameter part 136 high frequency power supply 140 cooling part 150 on-off valve

Claims (4)

A fluid supply pipe communicating with the combustion chamber;
A first electrode provided in the fluid supply pipe; a second electrode provided apart from the first electrode; and a high-frequency power source for supplying power to one of the first electrode and the second electrode; A plasma generator having
An on-off valve provided on the upstream side of the plasma generator in the fluid supply pipe;
An ignition device comprising:   The ignition device according to claim 1, wherein the fluid passing through the fluid supply pipe is a liquid. The fluid supply pipe is
A surrounding portion that surrounds the first electrode while maintaining a predetermined separation interval;
A diameter-reduced portion that is provided continuously to the surrounding portion and has an opening that opens to the combustion chamber, and has a smaller channel cross-sectional area than the surrounding portion,
The ignition device according to claim 1, comprising:   4. The device according to claim 1, further comprising: a part of the fluid supply pipe that surrounds at least a part of the first electrode; and a cooling unit that cools one or both of the first electrode. The ignition device described.

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