JP2019002289A - Combustion chamber of engine - Google Patents

Abstract

To reduce the cooling loss of an engine.SOLUTION: In a combustion chamber 50 of an engine 1, at least one of a piston top surface 51 and a bottom surface of a cylinder head 11 is a groove-formed surface 56 having a plurality of microscopic grooves 55 formed thereon. A width s of the groove 55 is set in a range of 2-250 μm, and an interfacial flow generation device 60 is extended and installed on the groove-formed surface 56. The interfacial flow generation device 60 is activated at least before a start of combustion of air-fuel mixture to deflect a main flow of gas flowing along the groove-formed surface 56 to a direction of the extension of the groove 55.SELECTED DRAWING: Figure 3

Description

  The technology disclosed herein relates to a technology for reducing engine cooling loss.

  In order to reduce engine cooling loss, multiple fine grooves, such as radial and concentric circles, extend along the main flow of gas (swirl flow, tumble flow, squish flow, etc.) formed in the combustion chamber. It is disclosed in Patent Document 1 that it is formed on a wall surface defining a combustion chamber (an upper surface of a piston, a lower surface of a cylinder head facing the upper surface of the piston, etc.).

  The main flow of gas is usually accompanied by fine vortices (diameter of μm level) swirling around the flow. This vortex causes microscopic turbulence. For this reason, when the main flow of gas passes near the wall surface of the combustion chamber, heat dissipation to the outside of the combustion chamber is promoted through the wall surface due to microscopic turbulence generated in the interface region. As a result, the high-temperature gas is cooled, resulting in energy loss (cooling loss). On the other hand, by forming a fine groove as in Patent Document 1 on the wall surface of the combustion chamber, the vortex is obstructed by the edge of the groove so that it is difficult to approach the bottom of the groove. Can be reduced.

  Regarding the technology to be disclosed, Patent Document 2 discloses an engine using a plasma actuator. In the engine, four arc-shaped plasma actuators are installed over the entire circumference on the inner peripheral surface of the intake port. When gas is introduced into the combustion chamber, the operation of these plasma actuators is controlled to make the gas flow strong or weak.

JP 2017-40216 A JP 2006-200019 A

  Even if the fine grooves as in Patent Document 1 are formed on the wall surface of the combustion chamber, the flow direction of the gas flowing along the wall surface having these grooves does not coincide with the direction in which the grooves extend, and there is a deviation between them. When it occurs, it has been found that the effect of suppressing heat dissipation decreases.

  Therefore, an object of the technology disclosed herein is to improve the effect of reducing engine cooling loss by allowing specific fine grooves formed on the wall surface of the combustion chamber to efficiently suppress heat dissipation.

  The disclosed technique is defined by an upper surface of a piston, a peripheral surface of a cylinder that accommodates the piston in a reciprocable manner, and a lower surface of a cylinder head that faces the upper surface of the piston, and the upper surface of the piston and the cylinder The present invention relates to a combustion chamber of an engine in which at least one of the lower surfaces of the head is a groove forming surface on which a plurality of fine grooves are formed.

  The width of the groove is set in a range of 2 to 250 μm, and an interfacial flow generation device that generates an interfacial flow that flows along the groove forming surface is installed so as to spread on the groove forming surface. At least before the combustion of the air-fuel mixture starts, the interface flow generation device operates to deflect the main flow of the gas flowing along the groove forming surface in the direction in which the groove extends.

  That is, in the combustion chamber of this engine, among the wall surfaces that define the combustion chamber, at least one of the upper surface of the piston and the lower surface of the cylinder head has a plurality of fine grooves (micro grooves) that can provide a heat radiation suppressing effect. Is formed. Accordingly, an effect of reducing the cooling loss can be obtained.

  Further, an interfacial flow generating device for generating interfacial flow flowing along the microgrooves is installed on the groove forming surface so that the interfacial flow is generated at least before the combustion of the air-fuel mixture starts. The generating device is activated to deflect the main flow of gas flowing along the groove forming surface in the direction in which the microgroove extends.

  Therefore, even if the flow direction of the main flow of the gas flowing along the groove forming surface does not coincide with the direction in which the micro grooves extend and a large deviation occurs between them, the interface flow generation device is activated. The deviation can be corrected and reduced. As a result, a decrease in the heat dissipation suppression effect can be suppressed, and the effect of reducing the engine cooling loss is improved.

  The width of the groove is preferably set to a size equal to or greater than the depth of the groove. By setting the groove width in this way, the above effect can be further enhanced.

  When combustion of the air-fuel mixture begins, the maximum temperature is reached in the combustion chamber, and the temperature difference between the gas in the combustion chamber and the groove forming surface increases. Therefore, if the interfacial flow generating device is operated at least before the combustion of the air-fuel mixture starts, it is effective because the effect of suppressing the heat dissipation of the microgroove can be appropriately exhibited at the timing at which heat is most easily released.

  Specifically, the interface flow generation device may be operated in the second half of the compression stroke. Then, before the combustion of the air-fuel mixture starts, the flow direction of the main flow of the gas flowing along the groove forming surface can be stably corrected and optimized. Since the operation time of the interfacial flow generation device can be minimized, power consumption can be prevented and fuel consumption can be improved.

  More specifically, a squish area for generating a squish flow is formed in a peripheral portion of the combustion chamber, and the groove forming surface facing the squish area is formed to extend in the flow direction of the squish flow. A groove and the interfacial flow generation device may be arranged, and the interfacial flow generation device may generate the interfacial flow in the same direction as the squish flow toward the radially inner side of the cylinder.

  In this case, since a squish area for generating a squish flow is formed in the peripheral portion of the combustion chamber, the squish flow is usually dominant in the gas flow when the temperature in the combustion chamber becomes the highest. Since the micro groove is formed on the groove forming surface facing the squish area so as to extend in the flow direction of the squish flow, a high heat radiation suppressing effect can be obtained.

  Further, the interfacial flow generation device generates interfacial flow in the same direction as the squish flow (forward squish flow) directed radially inward of the cylinder. In the compression stroke before the combustion of the air-fuel mixture begins, a forward squish flow is formed in the squish area. The interfacial flow generation device generates interfacial flow in the same direction. For example, even if the influence of swirl flow or tumble flow remains strongly in the combustion chamber, it is smooth and efficient in combination with forward squish flow. In addition, the flow direction of the gas flowing through the interface region can be deflected in the direction in which the microgroove extends. Therefore, an even higher heat dissipation suppression effect can be obtained.

  The engine includes a swirl flow generation mechanism that generates a swirl flow in the combustion chamber, and a flow of the swirl flow that flows along the groove forming surface is deflected by the interface flow generation device. Also good.

  In this case, the swirl flow generation mechanism is activated, and in the squish area when the combustion chamber reaches the highest temperature, the gas flow direction is biased in the circumferential direction, and the swirl flow is dominant instead of the squish flow. Can be. In such a case, the microgroove cannot sufficiently perform its function, resulting in a decrease in the heat dissipation suppression effect. On the other hand, if the interfacial flow in the swirl flow is deflected by the interfacial flow generation device, the original function of the microgroove can be exhibited, and the decrease in the heat dissipation suppression effect can be suppressed.

  Preferably, a plasma actuator is used for the interface flow generation device, and the plasma actuator is disposed so as to extend in a direction intersecting the groove.

  If a plasma actuator is used for the interfacial flow generation device, highly accurate interfacial flow can be generated relatively easily. If the plasma actuator is arranged so as to extend in a direction crossing the microgroove, an interfacial flow that flows in the direction in which the microgroove extends is generated, and the original function of the microgroove can be exhibited. Accordingly, it is possible to suppress a decrease in the heat dissipation suppression effect.

  When the upper surface of the piston is the groove forming surface, a device power supply unit capable of storing power to supply power to the interface flow generation device to the piston, and a device control unit for controlling the interface flow generation device And wirelessly feed and communicate with the device power supply unit and the device control unit.

  This eliminates the need for complicated wiring for the reciprocating piston. Since the piston is provided with a device power supply unit capable of storing electricity, even when wireless power feeding is performed, power can be stably supplied to the interface flow generation device and the device control unit. In addition, since the device control unit can control the interface flow generation device independently from the outside of the piston, the interface flow generation device can be stably operated even by wireless communication.

  According to the disclosed technique, since the fine groove having a specific structure capable of suppressing heat dissipation is formed in a wide range of the wall surface of the combustion chamber, an effect of reducing the cooling loss of the engine can be obtained. If the flow direction of the main flow of gas flowing near the wall is greatly deviated from the groove extension direction, the effect of reducing the engine cooling loss will be reduced. As a result, it is possible to suppress a reduction in the cooling loss reduction effect of the engine.

FIG. 1 is a schematic cross-sectional view showing an example of an engine to which a combustion chamber of the present invention is applied. FIG. 2 is a schematic diagram showing an enlarged cross-sectional structure of the combustion chamber. FIG. 3 is a view showing the upper surface of the piston when viewed from the direction of arrow I in FIG. FIG. 4 is a view showing the combustion chamber ceiling when viewed from the direction of arrow II in FIG. FIG. 5 is a diagram illustrating the structure of the microgroove, and is a schematic cross-sectional view indicated by arrows XX in the enlarged view of FIG. FIG. 6 is a graph showing the relationship between the deviation angle of the flow direction of the gas flowing in the interface region with respect to the groove extending direction of the micro groove and the reduction rate of the heat transfer coefficient of the groove forming surface. FIG. 7 is a diagram illustrating the structure of the interfacial flow generation device, and is a schematic cross-sectional view indicated by arrows YY in the enlarged view of FIG. FIG. 8 is a diagram illustrating the deflection action of the interfacial flow by the interfacial flow generation device. FIG. 9 is a schematic perspective view showing an example of a crossing portion between the microgroove and the interface flow generation device. FIG. 10 is a diagram illustrating the timing for operating the interface flow generation device. FIG. 11A is a schematic plan view illustrating a modified example of the microgroove formation pattern. FIG. 11B is a schematic plan view showing a modified example of the microgroove formation pattern. FIG. 11C is a schematic plan view showing a modified example of the microgroove formation pattern.

  Hereinafter, embodiments of the disclosed technology will be described in detail based on the drawings. However, the following description is merely illustrative in nature and does not limit the present invention, its application, or its use.

<Engine configuration>
FIG. 1 shows an example of an engine to which the combustion chamber of the present invention is applied. The engine 1 is a reciprocating piston engine, and is mainly used as a power source for automobiles. The engine 1 includes an engine main body 2, an intake / exhaust system 3 that performs intake and exhaust with respect to the engine main body 2, and a PCM 4 (powertrain control module) that controls the operation of the engine 1.

  The fuel of the engine 1 is gasoline. However, gasoline containing bioethanol or the like may be used. That is, any fuel may be used as long as it is a liquid fuel mainly composed of gasoline.

  The engine body 2 includes a cylinder block 10 and a cylinder head 11 placed thereon. A plurality of cylindrical cylinders 12 are formed in the cylinder block 10 so as to extend in the vertical direction. That is, the engine 1 is a multi-cylinder engine (only one cylinder 12 is shown in FIG. 1). The upper opening of the cylinder 12 is blocked by the cylinder head 11.

  Each cylinder 12 accommodates a piston 13 so as to be slidable back and forth. The lower opening of the cylinder 12 is blocked by the piston 13. The piston 13 is connected to the crankshaft 15 via a connecting rod 14. As the piston 13 reciprocates inside the cylinder 12, the crankshaft 15 rotates, and the rotational power is output as the driving force of the automobile.

  A combustion chamber 50 (a space in which the air-fuel mixture burns) is formed in the upper part of the cylinder 12. Specifically, each of the side surface, the lower surface, and the upper surface of the upper space of the cylinder 12 is defined by the peripheral surface of the cylinder 12, the upper surface of the piston 13, and the lower surface of the cylinder head 11 facing the upper surface of the piston 13. Thus, the combustion chamber 50 is formed (the upper surface of the piston 13 constituting the lower surface of the combustion chamber 50 is also referred to as the piston upper surface 51, and the lower surface of the cylinder head 11 constituting the upper surface of the combustion chamber 50. Is also referred to as the combustion chamber ceiling surface 52). The details of the combustion chamber 50 will be described later.

  An intake port 17 and an exhaust port 18 that communicate with the combustion chamber 50 are formed in the cylinder head 11. The combustion chamber ceiling surface 52 is formed with an intake opening 19 that is a downstream end of the intake port 17 and an exhaust opening 20 that is an upstream end of the exhaust port 18. The upstream end of the intake port 17 opens to one side surface of the cylinder head 11 and is connected to an intake passage 21 (which constitutes the intake system of the intake / exhaust system 3) through which fresh air or EGR gas introduced into the combustion chamber 50 flows. Has been. The upstream end of the exhaust port 18 opens to the other side surface of the cylinder head 11 and is connected to an exhaust passage 22 (which constitutes the exhaust system of the intake / exhaust system 3) through which burned gas led out from the combustion chamber 50 flows. ing.

  An intake valve 23 that opens and closes the intake opening 19 and an exhaust valve 24 that opens and closes the exhaust opening 20 are assembled to the cylinder head 11. The intake valve 23 has an axial valve stem 23a and an umbrella-shaped valve head 23b provided at the lower end of the valve stem 23a. Similarly, the exhaust valve 24 also has a valve stem 24a and a valve head 24b. The intake opening 19 and the exhaust opening 20 are opened and closed by these valve heads 23 b and 24 b, and each valve head 23 b and 24 b has valve surfaces 23 c and 24 c facing the combustion chamber 50. Two intake openings 19 and two intake valves 23 and two exhaust openings 20 and exhaust valves 24 are provided in each cylinder 12.

  An intake flow control valve 25 (swirl flow generating mechanism) that controls the flow of intake air introduced into the combustion chamber 50 is provided in the intake passage 21 (specifically, the supply passage connected to one intake port 17) of the engine 1. Example) is installed. The intake flow control valve 25 adjusts the strength of the swirl flow in the combustion chamber 50 according to the opening. That is, when the opening degree of the intake flow control valve 25 is large, the strength of the swirl flow becomes weak, and when the opening degree of the intake flow control valve 25 is small, the flow of the intake air is restricted, thereby increasing the strength of the swirl flow. Becomes stronger.

  The cylinder head 11 is also provided with an intake valve mechanism 26 that drives the intake valve 23 and an exhaust valve mechanism 27 that drives the exhaust valve 24. The intake valve mechanism 26 drives the intake valve 23 in conjunction with the rotation of the crankshaft 15 to open and close the intake opening 19. The exhaust valve mechanism 27 drives the exhaust valve 24 in conjunction with the rotation of the crankshaft 15 to open and close the exhaust opening 20.

  The intake valve mechanism 26 incorporates a variable valve timing mechanism (intake VVT). The intake side VVT is an electric or hydraulic VVT, and changes the opening / closing timing of the intake valve 23 by continuously changing the rotation phase of the intake camshaft with respect to the crankshaft 15 within a predetermined angle range. Similarly, the exhaust valve mechanism 27 incorporates an exhaust side VVT. The exhaust-side VVT is also an electric or hydraulic VVT, and the opening / closing timing of the exhaust valve 24 is changed by continuously changing the rotation phase of the exhaust camshaft with respect to the crankshaft 15 within a predetermined angle range.

  The cylinder head 11 is also provided with a spark plug 28 that ignites the air-fuel mixture in the combustion chamber 50. One spark plug 28 is arranged for each cylinder. The spark plug 28 has an electrode 28 a that generates a spark at its tip, and is assembled to the cylinder head 11 so that the electrode 28 a is positioned facing the combustion chamber 50.

  The cylinder head 11 is provided with an injector 29 for injecting fuel. One injector 29 is also arranged for each cylinder. The injector 29 has a nozzle 29a of a multi-injection type or the like that injects fuel at the tip, and is assembled to the cylinder head 11 so that the nozzle 29a faces the combustion chamber 50. The injector 29 of each cylinder is connected through a fuel supply pipe 30 to a common common rail (not shown) that stores high-pressure fuel. The fuel accumulated in the common rail is supplied to each injector 29. Thereby, high pressure fuel can be injected from each injector 29 at the same pressure.

  In order to detect the operating state of the engine 1, various sensors such as a temperature sensor, an angle sensor, and a flow rate sensor are attached to the engine 1, although not shown. The PCM 4 controls each device constituting the engine 1 based on signals input from these sensors and various control data such as a map that is mounted in advance. For example, the opening degree of the intake flow control valve 25, the operation of the intake valve mechanism 26 and the exhaust valve mechanism 27, the ignition timing of the spark plug 28, the fuel injection timing and injection time by the injector 29, etc. It is controlled by the PCM 4 according to the state.

<Composition of combustion chamber 50>
FIG. 2 shows an enlarged cross-sectional structure of the combustion chamber 50. 3 shows the piston upper surface 51 when viewed from the direction of arrow I in FIG. 2, and FIG. 4 shows the combustion chamber ceiling surface 52 when viewed from the direction of arrow II in FIG. Reference symbol J is an axis passing through the center of the cylinder. The piston upper surface 51 and the combustion chamber ceiling surface 52 are provided with a plurality of micro grooves 55 and a plurality of interfacial flow generation devices 60, which will be described in detail separately.

  The combustion chamber ceiling surface 52 of the engine 1 has two inclined surfaces symmetrically positioned on both sides of the axis J (so-called pent roof shape). As shown in FIGS. 2 and 4, the combustion chamber ceiling surface 52 includes an intake side inclined surface 52a in which two intake openings 19 are arranged and an exhaust side inclined surface 52b in which two exhaust openings 20 are arranged. Have. Between the intake side inclined surface 52a and the exhaust side inclined surface 52b, a ridge surface 52c extending along the upper end edges of the intake side inclined surface 52a and the exhaust side inclined surface 52b is formed.

  Each of the intake-side inclined surface 52a and the exhaust-side inclined surface 52b is configured by a cup-shaped fine curved surface that is recessed upward with the axis J as the center, and gently inclines downward in the opposite directions. . The two intake openings 19 and the two exhaust openings 20 are arranged so as to be aligned along the ridge surface 52c. Each valve surface 23c, 24c is also formed of a fine curved surface, like the intake side inclined surface 52a and the exhaust side inclined surface 52b.

  Thereby, when the intake valve 23 is closed, the valve surface 23c is connected to the combustion chamber ceiling surface 52 without a step, and when the exhaust valve 24 is closed, the valve surface 24c is also connected to the combustion chamber ceiling surface 52 without a step. It is like that.

  The axis line J is located at the center of the ridge surface 52c, and the injector 29 is arranged on the cylinder head 11 so that the center line is located in parallel with the vicinity of the axis line J. The nozzle 29a faces the combustion chamber 50 from the approximate center of the ridge surface 52c. The spark plug 28 is disposed at a position adjacent to the injector 29 of the cylinder head 11 in an inclined state. The electrode 28a is disposed close to the nozzle 29a in the longitudinal direction of the ridge surface 52c, and faces the combustion chamber 50 from substantially the center of the ridge surface 52c.

  As shown in FIGS. 2 and 3, the piston upper surface 51 is formed in a shape corresponding to the combustion chamber ceiling surface 52. In other words, the piston upper surface 51 is formed with an intake side facing inclined surface 51a and an exhaust side facing inclined surface 51b facing the intake side inclined surface 52a and the exhaust side inclined surface 52b, respectively. Each of the intake side facing inclined surface 51a and the exhaust side facing inclined surface 51b has a curvature equivalent to that of each of the intake side inclined surface 52a and the exhaust side inclined surface 52b and is slightly swelled upward about the axis J. It is composed of a fine curved surface. Accordingly, the interval between the intake-side opposing inclined surface 51a and the intake-side inclined surface 52a and the interval between the exhaust-side opposing inclined surface 51b and the exhaust-side inclined surface 52b (interval in the axis J direction) are determined by the piston 13. Although it varies depending on the position, it is substantially constant in the radial direction.

  A cavity 53 (depression) is also formed in the piston upper surface 51. The cavity 53 is located in the center portion of the piston upper surface 51 and has an oval-shaped opening edge whose major axis is parallel to the ridge surface 52c. The wall surface of the cavity 53 is formed by a curved surface that continues to the opening edge, and the axis J passes through the center of the bottom.

  During operation of the engine 1, the piston 13 reciprocates, and the exhaust valve 24 and the intake valve 23 are opened and closed at a predetermined timing. Thus, combustion is injected from the injector 29 at a predetermined timing, and ignition is performed by the spark plug 28 at a predetermined timing. Thereby, in the combustion chamber 50, the combustion cycle which consists of each process of intake, compression, expansion, and exhaust_gas | exhaustion is performed. The engine 1 is an engine having a relatively high compression ratio (geometric compression ratio). When the piston 13 is located at the top dead center, the piston upper surface 51 is placed on the combustion chamber ceiling surface 52 as shown in FIG. Proximity.

(Gas flow)
In the combustion chamber 50 where the combustion cycle is performed, various gas flows are formed. The main flow (main flow) of these gases can be roughly classified into a swirl flow, a tumble flow, and a squish flow when modeled based on the direction and form. The swirl flow is a gas flow swirling around an axis J (lateral vortex), and the tumble flow is a gas flow swirling around an axis orthogonal to the axis J (longitudinal vortex). Both are flows that swirl in the combustion chamber 50 greatly.

  In the engine 1, a swirl flow can be generated by the intake flow control valve 25 and the strength thereof can be adjusted. Even if the intake flow control valve 25 is not provided, a swirl flow can be generated and its strength can be adjusted by changing the opening / closing timing of the intake valve 23 by the intake valve mechanism 26 having the intake VVT. Therefore, the intake valve mechanism 26 can also constitute a swirl flow generating mechanism.

  On the other hand, the squish flow is a gas flow formed in the squish area 54 provided in the peripheral portion of the combustion chamber 50. In the combustion chamber 50, a squish area 54 is constituted by a space between the intake-side opposing inclined surface 51a and the intake-side inclined surface 52a and a space between the exhaust-side opposing inclined surface 51b and the exhaust-side inclined surface 52b. The The squish area 54 is formed in the process of moving from the compression stroke to the expansion stroke, where the piston 13 is located near the compression top dead center.

  As shown by arrows in FIG. 2, the squish flow is a gas flow directed in the radial direction of the cylinder 12. In the squish flow, gas is pushed out in the compression stroke in which the piston 13 rises, and the gas is drawn in in the radially inward flow (forward squish flow), and in the expansion stroke in which the piston 13 descends, and radially outward. There is a heading flow (reverse squish flow).

  It is known that the main flow of these gases is accompanied by a fine vortex (micro vortex ms) having a diameter of μm and swirling around the flow as a secondary flow (secondary flow). The micro vortex ms causes microscopic turbulence. Therefore, when the main flow of gas passes near the wall surface of the combustion chamber 50, heat dissipation to the outside of the combustion chamber 50 is promoted through the wall surface due to microscopic turbulence generated in the interface region. As a result, the high-temperature gas is cooled, resulting in energy loss (cooling loss).

  It is known that heat dissipation can be suppressed by forming fine grooves set to a predetermined size on the wall surface of the combustion chamber 50 against the promotion of heat dissipation due to such microvortex ms (patent) Reference 1). As shown in FIGS. 3 and 4, both the piston upper surface 51 and the combustion chamber ceiling surface 52 have such fine grooves on the wall surface of the combustion chamber 50 of the engine 1 in order to suppress cooling loss. (Micro groove 55) is formed.

(Micro groove 55)
The micro groove 55 is formed so as to extend in the flow direction of the main flow of the gas flowing along the wall surface on which the micro groove 55 is formed. The greater the temperature difference between the gas and the wall surface, the higher the heat dissipation suppression effect. Therefore, the micro grooves 55 are preferably formed in accordance with the flow direction of the main stream when the temperature in the combustion chamber 50 becomes the highest temperature, but the formation pattern can be appropriately selected according to the specifications of the engine 1.

  As shown in FIGS. 3 and 4, in this configuration example, micro grooves 55 are formed in accordance with the squish flow, and both the piston upper surface 51 and the combustion chamber ceiling surface 52 constituting the squish area 54 are formed. The micro-groove 55 is formed (the surface on which the micro-groove 55 is formed is also referred to as “groove forming surface 56”). Specifically, a plurality of microgrooves 55 are provided in substantially the entire area of each of the intake-side opposed inclined surface 51a and the exhaust-side opposed inclined surface 51b of the piston upper surface 51, and in the range from the peripheral edge of the cavity 53 to the outer edge of these inclined surfaces. Is formed. In addition, on the combustion chamber ceiling surface 52, the entire area of each of the intake side inclined surface 52a and the exhaust side inclined surface 52b including the valve surfaces 23c and 24c of the intake valve 23 and the exhaust valve 24, from the peripheral portion of the ridge surface 52c. A plurality of microgrooves 55 are formed in a range reaching the outer edge of these inclined surfaces.

  These micro grooves 55 are arranged so as to extend radially from the radial center of the cylinder 12 in accordance with the flow direction of the squish flow flowing in the squish area 54 in the radial direction. The microgrooves 55 are arranged so densely that adjacent microgrooves 55 are in contact with each other. However, for convenience, the illustrated microgrooves 55 are shown in a simplified manner.

  As shown in FIG. 5, the width s (maximum width s between both side edges) of the microgroove 55 is set to be smaller than the diameter d of the microvortex ms. As a result, the micro vortex ms cannot enter the micro groove 55, and a microscopic turbulence is generated at a position away from the wall surface as compared with the case where the groove forming surface 56 is flat. As a result, heat transfer between the gas and the groove forming surface 56 becomes difficult, and heat dissipation is suppressed. If the width s of the microgroove 55 is too small, the function as the microgroove 55 is impaired by approaching a smooth surface, so that it is set not to be too small.

  Such an appropriate width s of the microgroove 55 is set based on the flow velocity of the main flow of the gas. For example, the diameter d of the microvortex ms decreases as the flow velocity of the main gas flow increases. Accordingly, the width s of the microgroove 55 is also set accordingly. An example of an appropriate set value of the width s of the micro groove 55 for different rotational speeds and loads in the main operating region of the engine 1 will be shown below.

[Number of rotations] [Load] [Width s of micro-groove 55]
・ 1000 rpm / 250 kPa: 10 to 200 μm
・ 1000 rpm / 550 kPa: 7 to 250 μm
-2500 rpm / 900 kPa: 2.5-80 μm
・ 3250 rpm / 530 kPa: 2 to 70 μm
That is, the width s of the microgroove 55 is preferably set in the range of 2 μm to 250 μm. When the width s is smaller than 2 μm, the wall surface of the combustion chamber 50 becomes close to a smooth surface, and when the width s exceeds 250 μm, the microvortex ms easily enters the microgroove 55. None of them can be expected to reduce the cooling loss.

  It is preferable that the depth h of the microgroove 55 is also set appropriately according to the width s. The deeper the microgroove 55, the farther the microscopic turbulence can be moved away from the groove forming surface 56. However, when the microgroove 55 is deepened, the surface area of the groove forming surface 56 increases. When the surface area becomes large, it becomes easy to dissipate heat. Therefore, if the surface area of the groove forming surface 56 becomes too large, the heat dissipation is warped and promoted.

  Therefore, the width s of the microgroove 55 is preferably set to a size equal to or greater than the depth h. Specifically, the ratio (h / s) of the depth h to the width s of the microgroove 55 may be set in the range of 0.5 to 1.0. From these facts, by setting the width s in the range of 2 μm to 250 μm to a depth s greater than or equal to the depth h, it is possible to form the microgroove 55 excellent in the cooling loss reduction effect. Within these ranges, the width s and the depth h of the microgroove 55 may not be uniform over the entire length. That is, the width s and the depth h may gradually increase from one end to the other end, or the width s and the depth h may partially differ. However, the micro groove 55 having a uniform width s and depth h is advantageous in that it can be easily processed.

  The cross-sectional shape of the micro-groove 55 can be set as appropriate according to specifications such as a V shape, a U shape, an arc shape, a rectangular shape, etc. (in this configuration example, a V-shaped cross-sectional shape is illustrated). As the number of the micro grooves 55 per unit area is larger, the effect of reducing the cooling loss is enhanced. Therefore, it is preferable that the space between adjacent micro grooves 55 is narrow. Therefore, it is particularly preferable that the side edge of the micro groove 55 coincides with the side edge of the adjacent micro groove 55, but there is a flat region between the adjacent micro grooves 55 as shown in FIG. It may be.

(Interface flow generation device 60)
In the engine 1 in which the squish area 54 is provided, the squish flow is dominant in the gas flow when the temperature in the combustion chamber 50 becomes the highest. Therefore, the formation pattern of the micro grooves 55 on the groove forming surface 56 facing the squish area 54 is adapted to the squish flow.

  However, as described above, in the combustion chamber 50, various gas flows may be formed at various timings in order to achieve efficient combustion. For example, the swirl flow is strengthened by the intake flow control valve 25, or the ratio of the dominant gas main flow is changed by changing the opening / closing timing of the intake valve 23 or by the level of the engine speed. Therefore, depending on the operating state of the engine 1, the swirl flow or the tumble flow may be dominant in the squish area 54 when the temperature in the combustion chamber 50 is the highest. In addition, the gas flow in the squish area 54 may change in a temperature range around the combustion chamber 50 where the temperature is highest.

  On the other hand, if the flow direction of the gas flowing along the groove forming surface 56 does not coincide with the direction in which the micro groove 55 extends (also referred to as the groove extending direction) and a deviation occurs between them, the heat dissipation suppressing effect is reduced. It has been found.

  FIG. 6 shows an angle (deviation angle: deg) in which the flow direction of the gas flowing along the groove forming surface 56 is deviated with respect to the groove extending direction, and the heat transfer coefficient in the groove forming surface 56 under a predetermined condition. The relationship with the reduction rate (%) is shown. The higher the heat transfer rate reduction rate, the higher the effect of suppressing heat dissipation. When the ratio of the depth h to the width s of the micro groove 55 (h / s) is 0.5, the solid line including the black circle mark indicates that the solid line including the white square mark has an h / s of 1.0. In the case of.

  In any case, when the deviation angle exceeds about 15 deg, a tendency that the effect of suppressing heat dissipation decreases as the deviation angle increases. Therefore, the deviation angle is preferably small and more preferably within 15 deg.

  Therefore, even if the micro groove 55 is formed on the wall surface of the combustion chamber 50, the flow direction of the gas flowing along the groove forming surface 56 is made to coincide with the groove extending direction as much as possible in order to efficiently obtain the heat radiation suppressing effect. There is a need. However, simply forming the microgroove 55 cannot cope with various gas flow directions. Therefore, in the combustion chamber 50 of the engine 1, an interface flow generation device 60 that generates a flow of gas (interface flow) flowing along the groove forming surface 56 is installed together with the micro groove 55.

  As shown in FIGS. 3 and 4, the interfacial flow generating device 60 is a fine structure that looks like a linear appearance, and is installed so as to spread on the groove forming surface 56. In this configuration example, the interfacial flow generating device 60 extends so as to extend along each of the intake-side opposed inclined surface 51a and the exhaust-side opposed inclined surface 51b of the piston upper surface 51, that is, along the outer edge portion of the region constituting the squish area 54. Is installed. In addition, the interfacial flow generation device 60 extends along the outer edge portion of the region constituting the squish area 54 of each of the intake side inclined surface 52a and the exhaust side inclined surface 52b also on the ceiling surface 52 of the combustion chamber 50. is set up. These interfacial flow generation devices 60 are arranged so as to extend in a direction (preferably, a direction orthogonal) intersecting with the plurality of radially extending micro grooves 55.

  FIG. 7 shows a cross-sectional structure of the interfacial flow generation device 60. A so-called plasma actuator is used for the interfacial flow generation device 60, and is constituted by a dielectric 61, an exposed electrode 62, a covered electrode 63, and the like.

  In the engine 1, the surface of the groove forming surface 56 (surface facing the combustion chamber 50) is covered with a coating layer having a specific structure, and the dielectric 61 is configured by the coating layer (coating layer 61. Also called).

  The covering layer 61 is formed of a material having a small heat capacity so that it can be easily heated and cooled. For example, the coating layer 61 can be formed of a silicone resin containing hollow particles. Specifically, the coating layer 61 can be formed using a silicone resin such as polyalkylphenylsiloxane containing fine ceramic hollow particles such as fly ash balloon, shirasu balloon, silica balloon, and airgel balloon.

  By forming a dielectric with such a covering layer 61, a heat shielding function can be imparted to the groove forming surface 56. Thereby, since heat dissipation is suppressed, the effect of reducing the cooling loss is further improved. Since the groove forming surface 56 has a higher temperature, an effect of suppressing the formation of carbon deposits in the micro grooves 55 can be expected.

  Both the exposed electrode 62 and the covered electrode 63 are formed of a conductor made of a thin film metal. In the interfacial flow generation device 60, the exposed electrode 62 and the covered electrode 63 are formed in a line shape or a belt shape. The thickness, width, shape, and the like of each of the exposed electrode 62 and the covered electrode 63 can be appropriately set according to specifications. Usually, the exposed electrode 62 and the coated electrode 63 are thin, and the thickness of the interfacial flow generating device 60 including these is only several μm to several hundred μm.

  The exposed electrode 62 is disposed on the outer surface side of the coating layer 61. Part of the exposed electrode 62 is preferably exposed to the combustion chamber 50. On the other hand, the covering electrode 63 is disposed on the inner surface side of the covering layer 61 with the covering layer 61 that is a dielectric interposed between the covering electrode 61 and the exposed electrode 62. The covered electrode 63 is arranged offset to a position away from the installation position of the exposed electrode 62 so that a part away from the exposed electrode 62 is generated along the groove forming surface 56.

  Each of the exposed electrode 62 and the covered electrode 63 is electrically connected to a power source capable of high output, for example, several KHz or more and several tens of kV or more, and can supply power.

  Specifically, as shown in FIG. 1, a head side device unit 64 corresponding to the interface flow generation device 60 installed on the ceiling surface 52 of the combustion chamber 50 is attached to the cylinder head 11. A piston-side device unit 65 corresponding to the interfacial flow generation device 60 installed on the upper surface 51 is attached to the inside of the piston 13.

  As shown in FIG. 2, the head side device unit 64 is connected to each interface flow generation device 60 installed on each of the intake side inclined surface 52a and the exhaust side inclined surface 52b through an electric wiring 66a. The piston-side device unit 65 is connected to each interfacial flow generation device 60 installed on the intake-side opposing inclined surface 51a and the exhaust-side opposing inclined surface 51b through the electrical wiring 66b.

  The head-side device unit 64 is connected to the PCM 4 and the battery 5 that is a main power source through a cable 67. Therefore, the interface flow generation device 60 installed on the ceiling surface 52 of the combustion chamber 50 is supplied with power and communicates by wire through the head-side device unit 64.

  On the other hand, the piston-side device unit 65 includes a device power supply unit 65a capable of storing power to supply power to the interface flow generation device 60, a device control unit 65b for controlling the interface flow generation device 60, and the device power supply unit 65a and the device. A device receiver 65c that supplies power and a control signal to each of the controllers 65b is incorporated. A transmitter 68 that enables wireless power feeding and communication with the device receiver 65c is disposed in the vicinity of the engine body 2. The transmitter 68 is connected to the PCM 4 and the battery 5 as the main power source through the cable 67.

  Therefore, the interfacial flow generating device 60 installed on the piston upper surface 51 is wirelessly fed and communicated through the transmitter 68 and the piston-side device unit 65. Since the piston-side device unit 65 is provided with a device power supply unit 65a capable of storing electricity, even when wireless power feeding is performed, power can be stably supplied to the interface flow generation device 60 and the device control unit 65b. . Since the device controller 65b can control the interface flow generation device 60 independent of the PCM 4, the interface flow generation device 60 can be stably operated even by wireless communication.

  The interfacial flow generation device 60 operates by supplying a high voltage. That is, when a high voltage is applied between the exposed electrode 62 and the covered electrode 63 (GND), edge discharge occurs between the exposed electrode 62 and the covered electrode 63. As a result, in the interface region between the exposed electrode 62 and the coated electrode 63 facing the combustion chamber 50, a gas flow is induced from the exposed electrode 62 side toward the coated electrode 63 side. At this time, since plasma is generated in the interface region, ozone is generated. That is, the interfacial flow generation device 60 also functions as an ozone generation device.

  By operating the interfacial flow generation device 60, a gas flow (interfacial flow) flowing along the interface region of the groove forming surface 56 can be formed as indicated by an arrow in FIG. 7. Therefore, the flow direction of the main flow of the gas flowing along the groove forming surface 56 can be deflected or strengthened by the interface flow generation device 60. Specifically, when the flow direction of the main flow of the gas flowing along the groove forming surface 56 is different from the groove extension direction, the flow direction can be deflected in the groove extension direction. Further, when the flow direction of the main flow of the gas flowing along the groove forming surface 56 is the same as the groove extending direction, the flow can be strengthened.

  As shown in FIGS. 3 and 4, in this configuration example, the interface flow generation device 60 is disposed so as to extend along the outer edge portion of the region constituting the squish area 54. The exposed electrode 62 is disposed so as to be positioned on the radially outer side of the cylinder 12 with respect to the covered electrode 63.

  Therefore, as shown by the white arrow in FIG. 8, even if an external force that directs the flow in the circumferential direction acts on the main flow of the gas in the interface region of the squish area 54 due to the influence of the swirl flow, the interface flow generation device 60. As a result of the operation, at the outer edge of the squish area 54, as indicated by the thin arrows, the same interfacial flow toward the radially inner side of the cylinder as the forward squish flow is formed along the micro grooves 55. Thereby, the flow direction of the gas biased in the circumferential direction is deflected in the radial direction, and the deviation angle from the groove extending direction can be reduced. As a result, it is possible to suppress a decrease in the heat dissipation suppression effect.

  Since the direction of the interfacial flow formed by the interfacial flow generation device 60 is the same as that of the forward squish flow, if the interfacial flow generation device 60 is operated in accordance with the formation of the forward squish flow, the interface flow is smoothly and efficiently performed. The main flow direction of the gas flowing through the region can be deflected.

  Since the interfacial flow generation device 60 is arranged at the outer edge of the squish area 54, which is the upstream end of the forward squish flow, the interfacial flow generation device 60 is formed in a wide range of the groove forming surface 56 through which the forward squish flow flows. It can be influenced by interfacial flow and is effective.

  If the interfacial flow generating device 60 is arranged so as to extend in a direction intersecting the microgroove 55, an interfacial flow that flows in the groove extending direction can be formed on the groove forming surface 56. Therefore, the exposed electrode 62 and the microgroove 55 are It is not always necessary to cross (separate). However, if the exposed electrode 62 and the microgroove 55 intersect, the interfacial flow that flows in the groove extending direction can be more effectively formed by the combination with the unevenness of the microgroove 55. Therefore, it is preferable that at least a part of the exposed electrode 62 is formed so as to extend to the groove forming surface 56 in a state of intersecting with the micro groove 55.

  Since the microgroove 55 has a fine structure in units of μm, when the interfacial flow generation device 60 is installed so as to cross the microgroove 55, a step is generated in the microgroove 55, and the function of the microgroove 55 is caused by the interfacial flow generation device 60. May be disturbed. For this reason, as shown in FIG. 9, the exposed electrode 62 is continuously protruded from the micro groove 55 of the coating layer 61 so as not to inhibit the gas flow while generating the interfacial flow. It is preferable to form so as to.

  Specifically, the covering electrode 63 is installed at a predetermined portion on the surface of the base material such as the upper surface of the piston 13 or the lower surface of the cylinder head 11. Thereafter, the coating layer 61 is formed by coating or the like on the surface of the base material on which the coating electrode 63 is installed. At the same time as or after the formation of the coating layer 61, the exposed electrode 62 is installed at a predetermined site on the surface of the coating layer 61. At that time, the lower portion of the exposed electrode 62 is embedded in the coating layer 61. After that, the micro groove 55 is formed by cutting a predetermined portion of the upper surface of the piston 13 and the lower surface of the cylinder head 11 on which the exposed electrode 62 and the covering layer 61 are formed.

  In the case of cutting, even a large number of micro grooves 55 in units of μm can be formed with high accuracy and at low cost. A uniform micro groove 55 can be formed without distinction between the exposed electrode 62 and the covering layer 61. Since there is substantially no step in the microgroove 55, the function of the microgroove 55 is not impaired even if the interface flow generating device 60 is installed so as to intersect the microgroove 55. Since the microgroove 55 passes through the upper part of the exposed electrode 62 and the lower part of the exposed electrode 62 is continuous, the exposed electrode 62 applies a voltage to the entire exposed electrode 62 simply by energizing any part. it can. That is, wiring is easy.

  As shown in FIG. 9, by operating the interfacial flow generation device 60, a smooth gas flow that flows along the microgroove 55 can be formed. At this time, since the gas contains ozone, it is possible to effectively suppress the formation of carbon deposits due to the deposition of carbon particles in the micro grooves 55.

  The interfacial flow generation device 60 may be continuously operated during the operation period of the engine 1, but the amount of electric power consumption increases and affects fuel consumption. Therefore, the interfacial flow generation device 60 is preferably operated at an appropriate timing and period.

  Specifically, as shown in FIG. 10, the interfacial flow generation device 60 is formed in the combustion chamber 50 at least before the start of combustion of the air-fuel mixture, that is, by the ignition of the spark plug 28, in the first half of the expansion stroke. It is preferred to operate before the combusted mixture starts to burn. Furthermore, it is preferable to operate during the second half of the compression stroke (the second half of the half of the compression stroke). In particular, it is preferable to operate at a timing when the piston 13 is positioned near the compression top dead center.

  At this time, the combustion chamber 50 is in a state as shown in FIG. 2, and the piston 13 is raised toward the compression top dead center. Accordingly, a forward squish flow is formed in the squish area 54. Since the micro grooves 55 are formed in a pattern suitable for the flow direction of the squish flow, the deviation angle is small and heat dissipation can be efficiently suppressed. Even if the flow direction of the main flow of the gas flowing in the interface region is slightly deviated with respect to the groove extension direction, it is deflected in the groove extension direction by the operation of the interface flow generation device 60. Further, the forward squish flow is enhanced by the operation of the interfacial flow generating device 60.

  The combustion chamber 50 is compressed to the maximum at the compression top dead center, and the air-fuel mixture becomes hot. Immediately thereafter, combustion of the air-fuel mixture starts. Therefore, the aforementioned deviation angle can be reduced at the timing when the temperature in the combustion chamber 50 becomes the highest. As a result, since the decrease in the heat dissipation suppression effect can be effectively suppressed, an excellent cooling loss reduction effect can be obtained. Since the interfacial flow generation device 60 may be in an appropriate interfacial flow before the combustion of the air-fuel mixture starts, the operation of the interfacial flow generation device 60 may be stopped when the combustion of the air-fuel mixture starts.

  However, the interfacial flow generation device 60 may be operated in the first half of the expansion stroke in which the combustion of the air-fuel mixture is performed, following the second half of the compression stroke. That is, carbon particles are generated during the combustion of the air-fuel mixture. If the carbon particles enter and adhere to the microgroove 55 to form a carbon deposit, the microgroove 55 cannot exhibit its original function. On the other hand, in the first half of the expansion stroke, the temperature in the combustion chamber 50 is the highest, so the reactivity of carbon particles and ozone is high, and the carbon particles are easily oxidized by ozone. Therefore, by operating the interface flow generation device 60 also in the first half of the expansion stroke, it is possible to effectively suppress the carbon particles from adhering to the microgrooves 55.

  As described above, according to the disclosed combustion chamber 50 of the engine 1, since the micro grooves 55 that can suppress heat dissipation are formed in a wide range of the wall surface of the combustion chamber 50, an effect of reducing the cooling loss of the engine 1 is obtained. It is done. When the flow direction of the main flow of the gas flowing in the interface region is greatly deviated from the groove extending direction, the effect of reducing the cooling loss of the engine 1 is reduced, but the flow direction can be deflected by the interface flow generation device 60. Therefore, even if the flow direction of the main flow of the gas flowing through the interface region may be slightly different from the groove extending direction, it can be optimized.

<Modification>
The formation pattern of the microgroove 55 described above is only an example. The formation pattern of the micro grooves 55 can be appropriately set according to the specifications of the combustion chamber 50.

  FIG. 11A shows a modification of the groove forming surface 56 (illustrating the piston upper surface 51). For example, when each of the intake-side opposing inclined surface 51a, the intake-side inclined surface 52a, the exhaust-side opposing inclined surface 51b, and the exhaust-side inclined surface 52b is not a fine curved surface but a flat surface, the squish flow is It flows in the tilt direction. Therefore, in that case, as shown in FIG. 11A, the microgroove 55 is preferably formed to extend in the inclined direction.

  In the above-described embodiment, the case where the interface flow generation device 60 is installed only at the outer edge portion of the squish area 54 has been shown. However, as shown in FIG. May be installed. For example, in FIG. 11B, there are a plurality of interfacial flows in almost the entire area of each of the intake-side opposed inclined surface 51a and the exhaust-side opposed inclined surface 51b of the piston upper surface 51, and in the range from the peripheral edge of the cavity 53 to the outer edge of these inclined surfaces. A generation device 60 is installed. These interfacial flow generation devices 60 are arranged concentrically with respect to the center of the cylinder 12 so as to intersect with the plurality of radially extending micro grooves 55.

  In this way, if a large number of interfacial flow generation devices 60 are installed across the groove forming surface 56 so as to intersect with the micro grooves 55, the gas flow can be deflected more strongly. Even if the flow direction is significantly different from the groove extending direction, the function of the micro groove 55 can be exerted, so that heat radiation can be efficiently suppressed in various operating states of the engine 1, and the cooling loss of the engine 1 can be suppressed. Can be reduced.

  Further, in the above-described embodiment, the case where the squish flow becomes dominant during the period in which the inside of the combustion chamber 50 becomes high temperature is shown, but the swirl flow may become dominant. For example, there is a case where the swirl flow is strengthened by controlling the intake flow control valve 25 and the swirl flow is controlled to be the main in the above-described period instead of the squish flow. Further, the swirl flow may be mainly performed not in a period in which the inside of the combustion chamber 50 becomes high temperature but in a surrounding temperature zone.

  In such a case, since the direction of the micro vortex ms acting in the boundary region of the groove forming surface 56 also changes with the swirl flow, the micro grooves 55 are formed corresponding to the swirl flow as shown in FIG. 11C. It is good to arrange concentrically. In this case, the interfacial flow generating devices 60 are preferably arranged radially so as to be orthogonal to the micro grooves 55.

  In this case, for example, even if a gas flow that is biased in the radial direction of the cylinder 12 due to the squish flow is formed, the operation of the interface flow generation device 60 is deflected in the circumferential direction in which the microgroove 55 extends. Can do.

  The combustion chamber 50 of the engine according to the present invention is not limited to the above-described embodiment, and includes other various configurations. For example, in the combustion chamber 50 described above, both the combustion chamber ceiling surface 52 and the piston upper surface 51 are the groove forming surfaces 56, but only one of them may be used.

  In the above-described embodiment, the plasma actuator is exemplified as the interfacial flow generation device 60. However, the interfacial flow generation device 60 is not limited thereto. For example, if the technology of MEMS (Micro Electro Mechanical Systems) is used, directional interface flow can be generated.

DESCRIPTION OF SYMBOLS 1 Engine 2 Engine main body 12 Cylinder 13 Piston 28 Spark plug 29 Injector 50 Combustion chamber 51 Piston upper surface 52 Combustion chamber ceiling surface 53 Cavity 54 Squish area 55 Micro groove 56 Groove formation surface 60 Interface flow generation device J Axis

Claims (7)

An upper surface of the piston, a circumferential surface of a cylinder that accommodates the piston so as to be reciprocally slidable, and a lower surface of the cylinder head that faces the upper surface of the piston, and at least of the upper surface of the piston and the lower surface of the cylinder head One is a combustion chamber of an engine having a groove forming surface on which a plurality of fine grooves are formed,
The groove width is set in a range of 2 to 250 μm, and an interface flow generation device that generates an interface flow that flows along the groove forming surface is installed so as to spread on the groove forming surface,
A combustion chamber of an engine in which the interfacial flow generation device is operated at least before the combustion of the air-fuel mixture starts to deflect the main flow of gas flowing along the groove forming surface in a direction in which the groove extends. In the combustion chamber of the engine according to claim 1,
An engine combustion chamber in which the width of the groove is set to be larger than the depth of the groove. In the combustion chamber of the engine according to claim 1 or 2,
An engine combustion chamber in which the interfacial flow generating device operates in the latter half of the compression stroke. In the combustion chamber of the engine according to any one of claims 1 to 3,
A squish area for generating a squish flow is formed in a peripheral portion of the combustion chamber,
On the groove forming surface facing the squish area, the groove formed to extend in the flow direction of the squish flow, and the interface flow generation device are arranged,
A combustion chamber of an engine in which the interface flow generation device generates the interface flow in the same direction as the squish flow directed radially inward of the cylinder. In the combustion chamber of the engine according to any one of claims 1 to 4,
The engine includes a swirl flow generation mechanism that generates a swirl flow in the combustion chamber,
A combustion chamber of an engine in which a flow flowing along the groove forming surface in the swirl flow is deflected by the interface flow generation device. In the combustion chamber of the engine according to any one of claims 1 to 5,
A plasma actuator is used in the interface flow generation device,
An engine combustion chamber in which the plasma actuator is disposed so as to extend in a direction intersecting the groove. In the combustion chamber of the engine according to any one of claims 1 to 6,
The upper surface of the piston is the groove forming surface,
The piston is provided with a device power supply that can store electricity to supply power to the interface flow generation device, and a device control unit that controls the interface flow generation device.
An engine combustion chamber in which power supply and communication are performed wirelessly to the device power supply unit and the device control unit.

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