JP6436359B2 - Flow control device in combustion chamber - Google Patents

Description

  The present invention relates to a flow control device in a combustion chamber, and particularly controls the flow of gas in the combustion chamber in an engine in which a squish area is formed between a peripheral portion of a piston top surface and a ceiling surface of the combustion chamber. The present invention relates to a flow control device in a combustion chamber.

  Conventionally, improvement of engine combustion is performed by controlling the flow of gas in a combustion chamber. For example, in a spark ignition engine, a squish flow that flows along the combustion chamber ceiling surface and the piston crown surface is generated from the intake side and exhaust side squish areas at the end of the compression stroke, and the air-fuel mixture is collected in the center of the combustion chamber. Thus, a technique for improving the ignitability of fuel is known (for example, see Patent Document 1).

JP 2013-194561 A

  By the way, in order to improve the efficiency of the engine, it is necessary to reduce the cooling loss. However, when a squish flow or a reverse squish flow that flows along the ceiling surface of the combustion chamber and the piston crown surface is generated as in the engine described in Patent Document 1, the hot gas in the combustion chamber and the combustion are generated by these flows. Convective heat transfer between the chamber ceiling surface and the piston crown surface is promoted, resulting in an increase in cooling loss.

  The present invention has been made to solve the above-described problems of the prior art, and in an engine in which a squish area is formed between the peripheral edge of the piston top surface and the ceiling surface of the combustion chamber, An object of the present invention is to provide a flow control device in a combustion chamber that can reduce a cooling loss due to a reverse squish flow.

In order to achieve the above object, a flow control device in a combustion chamber according to a first aspect of the present invention provides a combustion chamber in an engine in which a squish area is formed between a peripheral portion of a piston top surface and a ceiling surface of the combustion chamber. A flow control device in a combustion chamber for controlling a flow of gas in a chamber, the plasma control device having a plasma actuator disposed in the combustion chamber, wherein the plasma actuator includes at least one set of dielectrics, a first exposed electrode, and an embedded And the dielectric is disposed along the ceiling surface of the combustion chamber and / or the top surface of the piston of the engine, the first exposed electrode is disposed on the combustion chamber side of the dielectric, and the embedded electrode is the dielectric disposed on the opposite side of the sandwich is exposed electrodes, the embedded electrode is disposed within the squish area, the first exposed electrode and the buried electrode of the plasma actuator is its They are respectively, disposed in the combustion chamber of an annular shape along the circumferential direction and concentrically, the first exposed electrode of annular shape, are arranged radially outside the combustion chamber than the annular embedded electrode , and characterized in that.
In the first invention of the present invention thus configured, the embedded electrode of the plasma actuator is disposed within the squish area on the ceiling surface of the combustion chamber and / or the top surface of the piston , and the first exposure of the annular shape. The electrode and the annular embedded electrode are arranged concentrically, and the annular first exposed electrode is arranged on the ceiling surface of the combustion chamber and / or the piston top surface on the radially outer side of the combustion chamber than the annular embedded electrode. As a result, plasma is generated in the discharge space between the end face of the exposed electrode and the dielectric by applying a high-frequency and high-voltage AC voltage to the exposed electrode and the buried electrode when the reverse squish flow occurs. Due to the volume force generated by the plasma, the inside of the squish area is directed radially inward of the combustion chamber along the combustion chamber ceiling and / or piston top surface. They are possible to induce a cormorant flow. In this way, by generating the flow in a direction that cancels the reverse squish flow, the flow velocity of the gas in the vicinity of the combustion chamber ceiling surface and the piston top surface can be suppressed, and the hot gas in the combustion chamber and the combustion chamber ceiling surface and the piston top surface can be suppressed. Convection heat transfer between the surfaces can be suppressed, and cooling loss due to the reverse squish flow can be reduced.

The flow control device in the combustion chamber according to the second invention of the present invention controls the flow of gas in the combustion chamber in an engine in which a squish area is formed between the peripheral portion of the piston top surface and the ceiling surface of the combustion chamber. A flow control device in a combustion chamber, comprising: a plasma actuator disposed in the combustion chamber; and a control means for controlling the plasma actuator, the plasma actuator comprising at least one set of dielectrics and a circumferential direction of the combustion chamber Formed in an annular shape along the circumferential direction of the combustion chamber disposed radially inward of the combustion chamber from the first exposed electrode in the annular shape. The plasma actuator is disposed within the squish area on the ceiling surface of the combustion chamber and / or the top surface of the piston of the engine. Controls the plasma actuator to generate a flow toward the radially inner side of the combustion chamber during the expansion stroke of the engine, characterized in that.
In the second invention of the present invention configured as described above, the control means applies a reverse squish flow to the plasma actuator disposed within the squish area on the ceiling surface of the combustion chamber and / or the piston top surface of the engine. Since control is performed so as to generate a flow toward the radially inner side of the combustion chamber during the expansion stroke that occurs, it is possible to generate a flow in a direction that cancels the reverse squish flow when the reverse squish flow occurs, The gas flow velocity in the vicinity of the combustion chamber ceiling and piston top surface can be suppressed, and convection heat transfer between the high temperature gas in the combustion chamber and the combustion chamber ceiling surface and piston top surface is suppressed, and cooling by reverse squish flow is performed. Loss can be reduced.
The flow control device in the combustion chamber according to the third aspect of the present invention controls the flow of gas in the combustion chamber in an engine in which a squish area is formed between the peripheral portion of the piston top surface and the ceiling surface of the combustion chamber. And a plasma actuator disposed in the combustion chamber, the plasma actuator comprising at least one set of dielectric, a second exposed electrode, and a buried electrode, The second exposed electrode is disposed on the combustion chamber side of the dielectric, and the embedded electrode is opposite to the exposed electrode across the dielectric. The embedded electrode is disposed in the range of the squish area, and the second exposed electrode and the embedded electrode of the plasma actuator are each in the circumferential direction of the combustion chamber. Arranged in a circular formed annularly and concentrically along the second exposed electrode of annular shape, than annular embedded electrode is disposed radially inwardly of the combustion chamber, characterized in that.
In the third invention of the present invention configured as described above, the embedded electrode of the plasma actuator is disposed within the squish area on the ceiling surface of the combustion chamber and / or the top surface of the piston, and has a second annular exposure. The electrode and the annular embedded electrode are arranged concentrically, and the annular second exposed electrode is located on the ceiling surface of the combustion chamber and / or the piston top surface on the radially inner side of the combustion chamber with respect to the annular embedded electrode. Since it is arranged, by applying high-frequency and high-voltage AC voltage to the exposed electrode and the buried electrode when the squish flow is generated, plasma is generated in the discharge space between the end face of the exposed electrode and the dielectric, Due to the volume force generated by the plasma, it is directed radially outward of the combustion chamber along the combustion chamber ceiling and / or piston top surface within the squish area. It is possible to induce a flow. In this way, by generating the flow in the direction to cancel the squish flow, the flow velocity of the gas in the vicinity of the combustion chamber ceiling surface and the piston top surface can be suppressed, and the high temperature gas in the combustion chamber and the combustion chamber ceiling surface and the piston top surface can be suppressed. The convective heat transfer between the squish flow and the squish flow can be reduced.
The flow control device in the combustion chamber according to the fourth aspect of the present invention controls the flow of gas in the combustion chamber in an engine in which a squish area is formed between the peripheral portion of the piston top surface and the ceiling surface of the combustion chamber. A flow control device in a combustion chamber, comprising: a plasma actuator disposed in the combustion chamber; and a control means for controlling the plasma actuator, the plasma actuator comprising at least one set of dielectrics and a circumferential direction of the combustion chamber A second exposed electrode formed in an annular shape along the annular shape, and an annular shape formed along the circumferential direction of the combustion chamber disposed radially outside the combustion chamber with respect to the annular second exposed electrode The plasma actuator is disposed within the squish area on the ceiling surface of the combustion chamber and / or the top surface of the piston of the engine. Controls the plasma actuator to generate a flow towards the radially outer side of the combustion chamber during the compression stroke of the engine, characterized in that.
In the fourth aspect of the present invention configured as described above, the control means generates a squish flow in the plasma actuator disposed within the squish area on the ceiling surface of the combustion chamber and / or the piston top surface of the engine. During the compression stroke, the flow is controlled so as to generate a flow toward the inner side in the radial direction of the combustion chamber, so that the flow can be generated in a direction to cancel the squish flow at the time when the squish flow is generated. The flow velocity of the gas in the vicinity of the surface and the piston top surface can be suppressed, and the convective heat transfer between the high temperature gas in the combustion chamber and the combustion chamber ceiling surface and the piston top surface is suppressed, thereby reducing the cooling loss due to the squish flow. be able to.

  According to the flow control device for a combustion chamber according to the present invention, in an engine in which a squish area is formed between the peripheral portion of the piston top surface and the ceiling surface of the combustion chamber, the cooling loss due to the squish flow or the reverse squish flow is reduced. be able to.

1 is a schematic configuration diagram of an engine to which a flow control device in a combustion chamber according to an embodiment of the present invention is applied. It is a block diagram which shows the electrical structure regarding the flow control apparatus in the combustion chamber by embodiment of this invention. It is a conceptual diagram which shows the basic composition of the plasma actuator by embodiment of this invention. 1 is a partial cross-sectional view of a piston and a cylinder head of an engine according to an embodiment of the present invention. It is a partial expanded sectional view of the squish area vicinity of the engine by embodiment of this invention. It is the top view of the plasma actuator by embodiment of this invention, (a) is the top view which looked at the plasma actuator arrange | positioned on the piston top surface from the upper direction of a piston, (b) was arrange | positioned on the ceiling surface of the combustion chamber. It is the top view which looked at the plasma actuator from the lower part of the ceiling surface. It is a partial expanded sectional view of the squish area vicinity of the engine by embodiment of this invention, (a) is a figure which shows operation | movement of the plasma actuator in a compression stroke, (b) is a figure which shows operation | movement of the plasma actuator in an expansion stroke. It is. It is the top view of the plasma actuator by the modification of embodiment of this invention, (a) is the top view which looked at the plasma actuator arrange | positioned at the piston top surface from the upper direction of a piston top, (b) is the ceiling of a combustion chamber It is the top view which looked at the plasma actuator arrange | positioned in the surface from the downward direction of the ceiling surface.

  Hereinafter, a flow control device in a combustion chamber according to an embodiment of the present invention will be described with reference to the accompanying drawings.

  First, an apparatus configuration of an engine according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic configuration diagram of an engine to which a flow control device in a combustion chamber according to an embodiment of the present invention is applied, and FIG. 2 shows an electrical configuration related to the flow control device in the combustion chamber according to an embodiment of the present invention. It is a block diagram.

  In FIG. 1, reference numeral 1 denotes an engine. The engine 1 is a gasoline engine that is mounted on a vehicle and supplied with a fuel containing at least gasoline. The engine 1 includes a cylinder block 4 provided with a plurality of cylinders 2 (only one cylinder 2 is shown in FIG. 1, but four cylinders 2 are provided in series, for example), and the cylinder block 4 And an oil pan 8 disposed below the cylinder block 4 and storing lubricating oil. A piston 14 connected to the crankshaft 12 via a connecting rod 10 is fitted in each cylinder 2 so as to be able to reciprocate. The cylinder head 6, the cylinder 2, and the piston 14 define a combustion chamber 16. The shape of the combustion chamber 16 is not limited to the shape illustrated. For example, the shape of the top surface of the piston 14 and the shape of the ceiling surface of the combustion chamber 16 can be appropriately changed.

  In the cylinder head 6, an intake port 18 and an exhaust port 20 are formed for each cylinder 2. The intake port 18 and the exhaust port 20 have an intake valve 22 and an exhaust for opening and closing the opening on the combustion chamber 16 side. Each valve 24 is disposed.

  The cylinder head 6 is also provided with an injector 26 (fuel injection valve) for directly injecting fuel into the cylinder 2 for each cylinder 2. The injector 26 is disposed so that the nozzle hole faces the inside of the combustion chamber 16 from the central portion of the ceiling surface 16 a of the combustion chamber 16. The injector 26 directly injects an amount of fuel into the combustion chamber 16 at an injection timing set according to the operating state of the engine 1 and according to the operating state of the engine 1.

  A spark plug 30 for forcibly igniting the air-fuel mixture in the combustion chamber 16 is also attached to the cylinder head 6. In the present embodiment, two spark plugs 30 are disposed between the intake valve 22 and the exhaust valve 24.

  A plasma actuator 28 is disposed on the top surface of the piston 14 and the cylinder head 6. Details of the plasma actuator 28 will be described later.

  The engine 1 is controlled by a powertrain control module (hereinafter referred to as PCM) 32. The PCM 32 includes a microprocessor having a CPU, a memory, a counter timer group, an interface, and a path connecting these units. The PCM 32 constitutes a controller.

  As shown in FIGS. 1 and 2, various signals including a detection signal of a crank angle sensor SW 12 that detects a rotation angle of the crankshaft 12 are input to the PCM 32.

  The PCM 32 determines the state of the engine 1 and the vehicle by performing various calculations based on these detection signals, and in response thereto, the injector 26, the spark plug 30, the plasma actuator 28, and various valves (throttle valve and EGR). A control signal is output to the actuator of the valve. Thus, the PCM 32 operates the engine 1. Although details will be described later, the plasma actuator 28 and the PCM 32 correspond to the flow control device in the combustion chamber in the present invention, and the PCM 32 functions as a control means for controlling the plasma actuator 28.

Next, a basic configuration of the plasma actuator 28 according to the embodiment of the present invention will be described with reference to FIG. FIG. 3 is a conceptual diagram showing a basic configuration of the plasma actuator 28 according to the embodiment of the present invention.
As shown in FIG. 3, the plasma actuator 28 includes a thin film-like dielectric 38, and an exposed electrode 40 and a buried electrode 42 arranged with the dielectric interposed therebetween. The exposed electrode 40 and the buried electrode 42 are arranged with their positions shifted along the planar direction of the dielectric 38. In FIG. 3, the exposed electrode 40 and the buried electrode 42 are arranged so as not to overlap in the normal direction of the dielectric 38, but the exposed electrode 40 and the buried electrode 42 are arranged so as to partially overlap. May be. An AC power supply 44 is connected to the exposed electrode 40 and the embedded electrode 42.

When an AC voltage of high frequency and high voltage (for example, several kHz, several tens of kV) is applied to the exposed electrode 40 and the embedded electrode 42 by the AC power supply 44, as shown in FIG. Plasma P is generated in the discharge space between. The plasma P generates a volume force from the exposed electrode 40 toward the embedded electrode 42, and the volume force induces a gas flow along the surface of the dielectric 38.
The magnitude of the volume force generated by the plasma P can be controlled by the voltage and frequency applied to the exposed electrode 40 and the embedded electrode 42.

  Next, the plasma actuator 28 according to the embodiment of the present invention will be described in detail with reference to FIGS. 4 is a partial cross-sectional view of the piston 14 and the cylinder head 6 according to the embodiment of the present invention, and FIG. 5 is a partially enlarged cross-sectional view of the vicinity of the squish area of the engine 1 according to the embodiment of the present invention. 6 is a plan view of the plasma actuator 28 according to the embodiment of the present invention, and FIG. 6A is a plan view of the plasma actuator 28 arranged on the top surface of the piston 14 as viewed from above the piston 14. FIG. 6B is a plan view of the plasma actuator 28 disposed on the combustion chamber ceiling surface 16a as viewed from below the combustion chamber ceiling surface 16a. FIG. 4 shows a view when the piston 14 is positioned at 10 ° before the compression top dead center.

  In the engine 1 according to the present embodiment, the combustion chamber 16 in which the combustion chamber ceiling surface 16a on the cylinder head 6 side is formed in a gable roof shape (pent roof shape) is applied. FIG. 4 is a cross-sectional view of a part of the piston 14 and the cylinder head 6 and the like cut along a plane along a line perpendicular to the pent roof-shaped ridge line constituting the combustion chamber 16.

  A cavity 34 recessed downward is formed at the center of the top surface of the piston 14. The cavity 34 is formed so that the planar shape when viewed from the axial direction of the cylinder 2 is substantially circular. An injector 26 is disposed immediately above the center of the cavity 34, and two spark plugs 30 are disposed in the recess of the cavity 34.

  Further, on the top surface of the piston 14, a peripheral edge portion 36 that extends from the outer edge of the cavity 34 to the outer edge of the upper surface of the piston 14 and surrounds the radially outer side of the cavity 34 is provided. A squish area SA is formed between the peripheral edge 36 of the top surface of the piston 14 and the combustion chamber ceiling surface 16a.

The plasma actuator 28 is disposed on the piston top surface peripheral portion 36 and the portion facing the peripheral portion 36 on the combustion chamber ceiling surface 16a.
Specifically, as shown in FIG. 5, with respect to the plasma actuator 28 disposed at the piston top surface peripheral portion 36, a dielectric 38 is disposed along the top surface of the piston 14. The exposed electrode 40 is disposed on the upper surface (that is, the combustion chamber 16 side), and the embedded electrode 42 is embedded on the opposite side of the exposed electrode 40 (that is, the piston 14 side) with the dielectric 38 interposed therebetween.
In the present embodiment, three embedded electrodes 42 are embedded in the piston top surface peripheral portion 36, and each of the embedded electrodes 42 is an inner exposed electrode disposed on the radially inner side of the combustion chamber 16 with respect to the embedded electrode 42. 40a and an outer exposed electrode 40b disposed on the radially outer side of the combustion chamber 16 with respect to the embedded electrode 42 are provided.

Further, with respect to the plasma actuator 28 disposed on the combustion chamber ceiling surface 16a, the dielectric 38 is disposed along the portion of the combustion chamber ceiling surface 16a facing the peripheral portion 36, and the lower surface of the dielectric 38 (that is, An exposed electrode 40 is disposed on the combustion chamber 16 side, and an embedded electrode 42 is embedded on the opposite side of the exposed electrode 40 (that is, the cylinder head 6 side) with the dielectric 38 interposed therebetween.
In the present embodiment, two embedded electrodes 42 are embedded in the combustion chamber ceiling surface 16a. For each embedded electrode 42, an inner exposed electrode 40a disposed radially inward of the combustion chamber 16 with respect to the embedded electrode 42. And an outer exposed electrode 40 b disposed on the radially outer side of the combustion chamber 16 with respect to the embedded electrode 42.

Further, as shown in FIG. 6, the exposed electrode 40 and the embedded electrode 42 are annularly arranged in a plan view.
Specifically, with respect to the plasma actuator 28 disposed on the piston top surface peripheral portion 36, as shown in FIG. 6A, three sets of inner exposed electrode 40a and outer exposed electrode 40b each formed in an annular shape. The embedded electrode 42 is disposed concentrically on the piston top surface peripheral edge 36.
As for the plasma actuator 28 disposed on the combustion chamber ceiling surface 16a, as shown in FIG. 6B, two sets of inner exposed electrode 40a, outer exposed electrode 40b and embedded electrode 42 formed in an annular shape, respectively. However, it is arrange | positioned concentrically at the peripheral part of the combustion chamber ceiling surface 16a.

  Next, the operation of the plasma actuator 28 according to the embodiment of the present invention will be described with reference to FIG. FIG. 7 is a partially enlarged cross-sectional view in the vicinity of the squish area SA of the engine 1 according to the embodiment of the present invention. FIG. 7A is a diagram showing the operation of the plasma actuator 28 during the compression stroke, and FIG. 7B is the expansion stroke. It is a figure which shows operation | movement of the plasma actuator 28 in it.

As shown in FIG. 7A, in the compression stroke, when the piston 14 moves up and the volume of the squish area SA decreases as the piston 14 approaches the combustion chamber ceiling surface 16a, the combustion chamber ceiling surface 16a and the piston top surface are reduced. A squish flow S (indicated by a dotted arrow in FIG. 7A) is generated from the squish area SA toward the cavity 34 along the surface peripheral edge 36.
At the time when the squish flow S is strongest (for example, around 10 ° before compression top dead center), the PCM 32 applies high-frequency and high-voltage AC voltages to the inner exposed electrode 40 a and the embedded electrode 42 by the AC power supply 44. As a result, plasma is generated in the discharge space between the end face of the inner exposed electrode 40a and the dielectric 38, and along the combustion chamber ceiling surface 16a and the piston top surface peripheral portion 36 by the volume force generated by the plasma. A flow toward the radially outer side of the combustion chamber 16 is induced. That is, in the vicinity of the combustion chamber ceiling surface 16a and the piston top surface peripheral portion 36, a flow is generated in a direction that cancels the squish flow S. Thereby, the flow velocity of the gas in the combustion chamber ceiling surface 16a and the vicinity of the top surface of the piston 14 can be suppressed, and the convection heat between the high temperature gas in the combustion chamber 16 and the combustion chamber ceiling surface 16a and the top surface of the piston 14 is achieved. Transmission can be suppressed and cooling loss can be reduced.

Further, as shown in FIG. 7B, in the expansion stroke, when the volume of the squish area SA increases as the piston 14 descends and the piston 14 moves away from the combustion chamber ceiling surface 16a, the combustion chamber ceiling surface 16a and the piston A reverse squish flow RS (indicated by a dotted arrow in FIG. 7B) is generated from the cavity 34 toward the squish area SA along the top peripheral edge 36.
At the time when the reverse squish flow RS becomes strongest (for example, around 10 ° after compression top dead center), the PCM 32 applies an AC voltage of high frequency and high voltage to the outer exposed electrode 40 b and the embedded electrode 42 by the AC power supply 44. As a result, plasma is generated in the discharge space between the end face of the outer exposed electrode 40b and the dielectric 38, and along the combustion chamber ceiling surface 16a and the piston top surface peripheral portion 36 by the volume force generated by the plasma. A flow toward the radially inner side of the combustion chamber 16 is induced. That is, in the vicinity of the surfaces of the combustion chamber ceiling surface 16a and the piston top surface peripheral portion 36, a flow is generated in a direction that cancels the reverse squish flow RS. Thereby, the flow velocity of the gas in the combustion chamber ceiling surface 16a and the vicinity of the top surface of the piston 14 can be weakened, and the convection heat between the high temperature gas in the combustion chamber 16 and the combustion chamber ceiling surface 16a and the top surface of the piston 14 is obtained. Transmission can be suppressed and cooling loss can be reduced.

Next, further modifications of the embodiment of the present invention will be described.
In the above-described embodiment, it has been described that the exposed electrode 40 and the embedded electrode 42 are formed in an annular shape in plan view, but may have different shapes.
For example, as shown in FIG. 8, a plurality of exposed electrodes 40 and embedded electrodes 42 formed in a straight line may be arranged in an annular shape in plan view. FIG. 8 is a plan view of a plasma actuator 28 according to a modification of the embodiment of the present invention. FIG. 8A is a plan view of the plasma actuator 28 disposed on the top surface of the piston 14 as viewed from above the piston 14. FIG. 8B is a plan view of the plasma actuator 28 disposed on the combustion chamber ceiling surface 16a as viewed from below the ceiling surface 16a.

  Specifically, with respect to the plasma actuator 28 disposed on the piston top surface peripheral portion 36, as shown in FIG. 8A, three sets of the inner exposed electrode 40a and the outer exposed electrode 40b, which are each formed in a straight line, are formed. And the embedded electrodes 42 are arranged in parallel to the circumferential direction of the combustion chamber 16 to form one block, and the eight blocks formed in the same manner surround the cavity 34 as a whole on the piston top surface peripheral portion 36. It may be arranged in a ring shape.

  As for the plasma actuator 28 disposed on the combustion chamber ceiling surface 16a, as shown in FIG. 8B, two sets of the inner exposed electrode 40a, the outer exposed electrode 40b, and the embedded electrode 42, which are each formed in a straight line, are formed. Are arranged in parallel to the circumferential direction of the combustion chamber 16 to form one block, and eight blocks formed in the same manner are arranged annularly on the peripheral edge of the combustion chamber ceiling surface 16a as a whole. Also good.

  In the above-described embodiment, the case where the plasma actuator 28 is disposed on the combustion chamber ceiling surface 16a and the piston top surface peripheral portion 36 has been described. However, the plasma actuator 28 is disposed on the combustion chamber ceiling surface 16a or the piston top surface peripheral portion. It may be arranged on one side of 36.

  Next, effects of the flow control device in the combustion chamber according to the above-described embodiment of the present invention and the modification of the embodiment of the present invention will be described.

  First, the embedded electrode 42 of the plasma actuator 28 is disposed within the squish area SA on the combustion chamber ceiling surface 16a and the top surface of the piston 14, and the inner exposed electrode 40a is disposed on the combustion chamber ceiling surface 16a and the top surface of the piston 14. In FIG. 1, the high-frequency and high-voltage AC voltages are applied to the inner exposed electrode 40a and the embedded electrode 42 when the squish flow S is generated. Plasma is generated in the discharge space between the end face of the exposed electrode 40a and the dielectric 38, and by the volume force generated by the plasma, the combustion chamber ceiling surface 16a and the top surface of the piston 14 are aligned within the squish area SA. Thus, the flow toward the radially outer side of the combustion chamber 16 can be induced. Thus, by generating a flow in a direction that cancels the squish flow S, the flow velocity of the gas in the vicinity of the combustion chamber ceiling surface 16a and the top surface of the piston 14 can be suppressed, and the high-temperature gas in the combustion chamber 16 and the combustion chamber can be suppressed. The convective heat transfer between the ceiling surface 16a and the top surface of the piston 14 can be suppressed, and the cooling loss due to the squish flow S can be reduced.

  Further, since the exposed electrode 40 and the embedded electrode 42 are arranged so as to correspond to the entire squish area SA formed between the piston top surface peripheral portion 36 and the combustion chamber ceiling surface 16a, a squish flow S is generated. By applying high-frequency and high-voltage AC voltage to the inner exposed electrode 40a and the embedded electrode 42 at the time, the squish flow S can be suppressed in the entire squish area SA, and the cooling loss due to the squish flow S can be more effectively reduced. Can be reduced.

  Further, since the outer exposed electrode 40b is disposed on the combustion chamber ceiling surface 16a and the top surface of the piston 14 on the radially outer side of the combustion chamber 16 with respect to the embedded electrode 42, the high frequency and high frequency are generated when the reverse squish flow RS is generated. By applying an alternating voltage of the voltage to the outer exposed electrode 40b and the buried electrode 42, plasma is generated in the discharge space between the end face of the outer exposed electrode 40b and the dielectric 38, and the volume force generated by the plasma causes Within the squish area SA, it is possible to induce a flow toward the radially inner side of the combustion chamber 16 along the combustion chamber ceiling surface 16 a and the top surface of the piston 14. Thus, by generating a flow in a direction that cancels the reverse squish flow RS, the flow velocity of the gas in the vicinity of the combustion chamber ceiling 16a and the top surface of the piston 14 can be suppressed, and the high-temperature gas and combustion in the combustion chamber 16 can be suppressed. Convective heat transfer between the chamber ceiling surface 16a and the top surface of the piston 14 can be suppressed, and cooling loss due to the reverse squish flow RS can be reduced.

  Further, the PCM 32 moves the plasma actuator 28 arranged in the range of the squish area SA on the combustion chamber ceiling 16a and the top surface of the piston 14 to the outside in the radial direction of the combustion chamber 16 during the compression stroke in which the squish flow S is generated. Since the flow is controlled so as to generate the flowing flow, the flow can be generated in the direction in which the squish flow S is canceled at the time when the squish flow S is generated, and thus, in the vicinity of the top surface of the combustion chamber ceiling surface 16a and the piston 14. The gas flow rate can be suppressed, and the convective heat transfer between the high-temperature gas in the combustion chamber 16 and the combustion chamber ceiling surface 16a and the top surface of the piston 14 is suppressed, thereby reducing the cooling loss due to the squish flow S. Can do.

  Further, the PCM 32 causes the plasma actuator 28 disposed in the range of the squish area SA on the combustion chamber ceiling surface 16a and the top surface of the piston 14 to move radially inward of the combustion chamber 16 during the expansion stroke in which the reverse squish flow RS is generated. Therefore, the flow can be generated in a direction that cancels the reverse squish flow RS at the time when the reverse squish flow RS is generated. As a result, the top of the combustion chamber ceiling 16a and the piston 14 can be generated. The flow velocity of the gas in the vicinity of the surface can be suppressed, the convective heat transfer between the high temperature gas in the combustion chamber 16 and the combustion chamber ceiling surface 16a and the top surface of the piston 14 is suppressed, and the cooling loss due to the reverse squish flow RS. Can be reduced.

1 Engine (Engine body)
14 Piston 16 Combustion chamber 16a Combustion chamber ceiling 28 Plasma actuator 32 PCM
34 Cavity 36 Peripheral part 38 Dielectric 40 Exposed electrode 40a Inner exposed electrode 40b Outer exposed electrode 42 Embedded electrode SA Squish area

Claims (4)

In an engine in which a squish area is formed between the peripheral edge of the piston top surface and the ceiling surface of the combustion chamber, the flow control device in the combustion chamber controls the flow of gas in the combustion chamber,
A plasma actuator disposed in the combustion chamber;
The plasma actuator includes at least one set of dielectric, a first exposed electrode, and an embedded electrode, and the dielectric is disposed along a ceiling surface of the combustion chamber and / or a piston top surface of the engine. The first exposed electrode is disposed on the combustion chamber side of the dielectric, and the embedded electrode is disposed on the opposite side of the first exposed electrode across the dielectric,
The embedded electrode is disposed within the squish area;
The first exposed electrode and the buried electrode of the plasma actuator are formed in an annular shape along the circumferential direction of the combustion chamber and arranged concentrically,
The flow control device in a combustion chamber, wherein the annular first exposed electrode is disposed radially outside the combustion chamber with respect to the annular embedded electrode. In an engine in which a squish area is formed between the peripheral edge of the piston top surface and the ceiling surface of the combustion chamber, the flow control device in the combustion chamber controls the flow of gas in the combustion chamber,
A plasma actuator disposed in the combustion chamber;
Control means for controlling the plasma actuator,
The plasma actuator includes at least one set of dielectrics, a first exposed electrode formed in an annular shape along a circumferential direction of the combustion chamber, and the combustion chamber more than the first exposed electrode in the annular shape. An embedded electrode formed in an annular shape along the circumferential direction of the combustion chamber disposed radially inside ;
The plasma actuator is disposed within the squish area on the ceiling surface of the combustion chamber and / or the piston top surface of the engine,
The flow control device in a combustion chamber, wherein the control means controls the plasma actuator so as to generate a flow toward a radially inner side of the combustion chamber during an expansion stroke of the engine. In an engine in which a squish area is formed between the peripheral edge of the piston top surface and the ceiling surface of the combustion chamber, the flow control device in the combustion chamber controls the flow of gas in the combustion chamber,
A plasma actuator disposed in the combustion chamber;
The plasma actuator includes at least one set of dielectric, a second exposed electrode, and an embedded electrode, and the dielectric is disposed along a ceiling surface of the combustion chamber and / or a piston top surface of the engine. The second exposed electrode is disposed on the combustion chamber side of the dielectric, and the embedded electrode is disposed on the opposite side of the second exposed electrode across the dielectric,
The embedded electrode is disposed within the squish area;
The second exposed electrode and the buried electrode of the plasma actuator are formed in an annular shape along the circumferential direction of the combustion chamber and arranged concentrically,
The flow control device in a combustion chamber, wherein the annular second exposed electrode is disposed radially inward of the combustion chamber with respect to the annular embedded electrode. In an engine in which a squish area is formed between the peripheral edge of the piston top surface and the ceiling surface of the combustion chamber, the flow control device in the combustion chamber controls the flow of gas in the combustion chamber,
A plasma actuator disposed in the combustion chamber;
Control means for controlling the plasma actuator,
The plasma actuator includes at least one pair of dielectrics, a second exposed electrode formed in an annular shape along the circumferential direction of the combustion chamber, and the combustion chamber more than the second exposed electrode in the annular shape. An embedded electrode formed in an annular shape along the circumferential direction of the combustion chamber disposed radially outside ,
The plasma actuator is disposed within the squish area on the ceiling surface of the combustion chamber and / or the piston top surface of the engine,
The flow control device in a combustion chamber, wherein the control means controls the plasma actuator so as to generate a flow toward a radially outer side of the combustion chamber during an expansion stroke of the engine.

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