JP6036586B2 - Internal combustion engine and control method thereof - Google Patents

Description

  The present invention relates to an internal combustion engine and a control method thereof.

  Conventionally, an internal combustion engine that promotes combustion in a combustion chamber by an electric field is known. For example, Non-Patent Document 1 describes an experimental result in which the shape of a flame changes depending on the polarity of an electrode provided in the center with respect to the flame in the sealing vessel. Patent Document 1 describes an internal combustion engine that forms an electric field between a gasket and a piston of a cylinder during a combustion stroke.

Yoshiyuki Wada and 4 others, “Study on Combustion Control of Combustible Mixture by Electric Field”, Proceedings of the 9th Joint Symposium on Internal Combustion Engines, Japan Society of Mechanical Engineers, July 1991, p. 45-50

Japanese Patent Laid-Open No. 01-036916

  However, in the internal combustion engine described in Patent Document 1, since the flame generated by the combustion of fuel is positively charged, it moves in the direction of the gasket serving as the negative electrode. In general, in the so-called cooling loss that is released to the outside through the wall surface that forms the combustion chamber with respect to the combustion heat that the flame has, the ratio of the amount of heat that is released to the outside through the piston and cylinder head portion is Relatively high. In the internal combustion engine described in Patent Document 1, since an electric field is formed only in a limited region connecting the end face of the piston and the gasket, the flame contacts the inner wall of the cylinder head portion and the inner wall of the cylinder liner portion, and cooling loss May not be able to be reduced.

  An object of the present invention is to provide an internal combustion engine that improves thermal efficiency.

The present invention relates to an internal combustion engine, a reciprocating piston, a cylinder having a combustion chamber whose volume is changed by reciprocating movement of a piston to be accommodated, and a fuel provided in the center of a cylinder head portion of the cylinder. The fuel supply means to be supplied, and the fuel supply means provided in the cylinder head near the ignition point of the fuel to be injected into the combustion chamber are given different potentials from the inner wall forming the combustion chamber, and the flame generated when the fuel in the combustion chamber burns A potential difference forming means for forming an electric field between the inner wall and the potential difference forming means on the inner wall, which is in the radial direction of the potential difference forming means on the inner wall and positioned between adjacent potential difference forming means. It is characterized by comprising a potential difference forming means and a first protrusion for forming an electric field .

  The fuel in the combustion chamber flows in a predetermined direction by the flow of gas in the cylinder such as a swirl flow or a tumble flow. For this reason, the flame produced | generated by combustion of a fuel in a combustion stroke flows in the flow direction of the gas in a cylinder. In the internal combustion engine of the present invention, the potential difference forming means and the combustion chamber are formed by utilizing the phenomenon that the flame generated in the combustion stroke of the internal combustion engine has the property of the positive electrode and behaves so as to repel the positive electrode and approach the negative electrode in the electric field. The position of the flame relative to the inner wall is adjusted so that the electric field formed between the inner wall and the inner wall does not oppose the flame flow. For example, when the electric field is formed from the potential difference forming means toward the inner wall, the flame approaches the inner wall of the combustion chamber. Thereby, the combustion heat of the flame transmitted to the inner wall increases, and the warm-up operation of the internal combustion engine can be shortened. Further, when the electric field is formed from the inner wall toward the potential difference forming means, the flame is separated from the inner wall of the combustion chamber. Thereby, since a gas layer such as air is formed between the flame and the inner wall, the combustion heat of the flame released to the outside through the inner wall is reduced, and the cooling loss can be reduced. Therefore, the internal combustion engine of the present invention can be operated efficiently.

1 is a schematic diagram of an internal combustion engine according to a first embodiment of the present invention. It is the II section enlarged view of FIG. It is a schematic diagram of the cross section of the combustion chamber of the internal combustion engine by 1st Embodiment of this invention. It is a principal part enlarged view of the internal combustion engine by 2nd Embodiment of this invention. It is a schematic diagram of the cross section of the combustion chamber of the internal combustion engine by 2nd Embodiment of this invention. It is a schematic diagram of the internal combustion engine by 3rd Embodiment of this invention. It is the VII part enlarged view of FIG. It is a principal part enlarged view of the internal combustion engine by 4th Embodiment of this invention. It is a principal part enlarged view of the internal combustion engine by 5th Embodiment of this invention. It is an expanded sectional view explaining the effect | action of the internal combustion engine by 5th Embodiment of this invention.

  Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
An internal combustion engine according to a first embodiment of the present invention will be described with reference to FIGS.

  The engine 1 according to the first embodiment is, for example, a direct injection type four-stroke engine that injects light oil directly into the combustion chamber 22. The engine 1 includes an intake system 10, a cylinder 20, a piston 30, a central electrode 35, an exhaust system 40, a control unit 50, and the like. In FIG. 1, the flow of air introduced into the intake system 10 is indicated by an arrow S1, and the flow of exhaust discharged from the exhaust system 40 to the atmosphere is indicated by an arrow S2.

  The intake system 10 supplies air in the atmosphere to the combustion chamber 22. The intake system 10 includes an intake pipe 12, a throttle valve 14, an intake valve 18, and the like.

  The intake pipe 12 is provided such that an intake passage 121 formed by the intake pipe 12 communicates with the combustion chamber 22 formed in the cylinder 20 and the atmosphere. The intake pipe 12 includes an air cleaner 13 that removes foreign substances contained in the atmosphere.

  The throttle valve 14 is provided on the combustion chamber 22 side as viewed from the air cleaner 13, that is, on the downstream side of the intake pipe 12. The throttle valve 14 adjusts the amount of air flowing through the intake pipe 12 according to the opening degree of an accelerator device (not shown) by the driver.

  The intake valve 18 is provided at a position where the intake pipe 12 and the cylinder 20 are connected. The intake valve 18 opens or closes according to the position of the reciprocating movement of the piston 30 relative to the cylinder 20, and supplies air flowing through the intake passage 121 to the combustion chamber 22 when the valve is opened.

  The exhaust system 40 releases exhaust gas, which is a gas after combustion in the combustion chamber 22, to the atmosphere. The exhaust system 40 includes an exhaust pipe 42, an exhaust temperature sensor 44, an exhaust valve 48, and the like.

  The exhaust pipe 42 is provided such that an exhaust passage 421 formed by the exhaust pipe 42 communicates the combustion chamber 22 and the atmosphere. An exhaust temperature sensor 44 is provided on the outer wall of the exhaust pipe 42. The exhaust temperature sensor 44 detects the temperature of the exhaust flowing through the exhaust passage 421.

  The exhaust valve 48 is provided at a position where the exhaust pipe 42 and the cylinder 20 are connected. The exhaust valve 48 opens or closes according to the position of the reciprocating movement of the piston 30 with respect to the cylinder 20, and causes the exhaust in the combustion chamber 22 to flow through the exhaust pipe 42 when the valve is opened.

  The cylinder 20 includes a cylinder head portion 24, a cylinder liner portion 26, and a crankcase portion 28.

  An intake port 244 communicating with the intake passage 121 and an exhaust port 245 communicating with the exhaust passage 421 are formed in the cylinder head portion 24. Further, a fuel injection valve 25 is provided in the approximate center of the cylinder head portion 24.

  The fuel injection valve 25 directly injects fuel into the combustion chamber 22. Fuel stored in a fuel tank (not shown) is supplied to the fuel injection valve 25 as “fuel supply means”. The fuel injection valve 25 corresponds to “fuel supply means” described in the claims.

  The central electrode 35 is provided at the end of the fuel injection valve 25 on the combustion chamber 22 side. As shown in FIG. 3, four central electrodes 35 are provided at equal intervals in the circumferential direction in the radially outward direction of the fuel injection valve 25. The central electrode 35 can apply a positive or negative voltage, and is given a potential different from that of the cylinder head 24, the cylinder liner 26, and the piston 30. The center electrode 35 is provided with a protrusion 351 at the tip. The center electrode 35 corresponds to “potential difference forming means” described in the claims.

The cylinder liner portion 26 is formed in a substantially cylindrical shape, and forms the cylinder head portion 24 and the piston 30 and the combustion chamber 22. A wall surface electrode 262 is provided on the inner wall surface 261 of the cylinder liner portion 26 that forms the combustion chamber 22. The wall surface electrodes 262 have the same potential as the cylinder liner portion 26, and four wall surface electrodes 262 are provided corresponding to the four central electrodes 35 provided. The inner wall surface 261 and the wall surface electrode 262 correspond to an “inner wall forming a combustion chamber” recited in the claims.
A flow path 265 through which cooling water for cooling the cylinder 20 flows is formed inside the side wall of the cylinder liner portion 26. The temperature of the cooling water flowing through the flow path 265 is detected by a water temperature sensor 27 provided on the side wall of the cylinder liner portion 26.

  The crankcase portion 28 is provided so as to be connected to an end portion of the cylinder liner portion 26 opposite to the side connected to the cylinder head portion 24. The crankcase part 28 accommodates the crank 281 inside.

  The piston 30 is accommodated so as to be capable of reciprocating in the radial direction of the cylinder liner portion 26.

  The control unit 50 applies a voltage to the central electrode 35 and the wall surface electrode 262 in accordance with the strength of the electric field formed by the central electrode 35 and the wall surface electrode 262 calculated based on various information and the timing of forming the electric field. Apply. The control unit 50 includes a calculation unit 52, a power supply 54, a boosting unit 56, and the like.

  The arithmetic unit 52 is a well-known small computer having a CPU, ROM, RAM, I / O, and a bus line connecting them. The calculation unit 52 is electrically connected to the throttle valve 14, the fuel injection valve 25, the water temperature sensor 27, the exhaust temperature sensor 44, and the like. The calculation unit 52 is an electric signal indicating the opening degree of the throttle valve 14 output from the throttle valve 14, an electric signal indicating the fuel injection amount output from the fuel injection valve 25, and the cooling water of the cylinder liner unit 26 output from the water temperature sensor 27. , An electrical signal indicating a crank angle output by a crank angle sensor (not shown), an electrical signal indicating an exhaust temperature output by an exhaust temperature sensor 44, and the like. The calculation unit 52 calculates the pressure of the combustion chamber 22 based on an electric signal indicating the opening degree of the throttle valve 14, and based on the electric signal indicating the opening degree of the throttle valve 14 and the electric signal indicating the exhaust temperature. The piston position is calculated based on an electric signal indicating the crank angle. The computing unit 52 calculates the optimum voltage value and current value for forming an electric field in the combustion chamber 22 based on these calculated values. In addition, the calculation unit 52 applies a voltage having a polarity in accordance with the operation state of the engine 1 to the central electrode 35 or the wall electrode 262 based on an electric signal indicating the temperature of the cooling water in the cylinder liner unit 26. The calculation unit 52 outputs the calculated voltage value and current value to the boosting unit 56.

  The booster 56 boosts the power supplied from the power supply 54 based on the voltage value, current value, and polarity output from the calculator 52. The boosted power is applied to the center electrode 35 and the wall surface electrode 262. Thereby, a desired electric field is formed in the combustion chamber 22.

  Next, the operation of the engine 1 will be described according to the stroke of the engine 1.

When the piston 30 at the top dead center moves to the bottom dead center, the intake valve 18 opens. Air flowing through the intake passage 121 is supplied to the combustion chamber 22 via the intake port 244 (intake stroke).
Next, when the piston 30 that has moved to the bottom dead center moves toward the top dead center, the intake valve 18 closes. The volume of the combustion chamber 22 is reduced by the movement of the piston 30 to the top dead center, and the air in the combustion chamber 22 is compressed (compression stroke).

Next, when the piston 30 moves to near the top dead center, the fuel is injected into the combustion chamber 22 by the fuel injection valve 25 in a plurality of times. The injected fuel burns when it reaches a predetermined temperature (combustion stroke). At this time, the control unit 50 sets the center electrode 35 to one of the negative polarity and the positive polarity, and sets the wall surface electrode 262 to one of the positive polarity and the negative polarity. Thereby, in the combustion chamber 22, an electric field is formed between the four central electrodes 35 and the four wall surface electrodes 262.
Further, the control unit 50 changes the polarities of the center electrode 35 and the wall surface electrode 262 in accordance with the operating state of the engine 1. Specifically, immediately after the engine 1 is started, the center electrode 35 is set to the positive electrode and the wall surface electrode 262 is set to the negative electrode. As a result, an electric field from the central electrode 35 toward the wall surface electrode 262 is formed in the combustion chamber 22. Further, when the engine 1 has elapsed for a certain time from the start, the center electrode 35 is set to the negative electrode and the wall surface electrode 262 is set to the positive electrode. Thereby, an electric field from the wall surface electrode 262 toward the center electrode 35 is formed in the combustion chamber 22.

  Here, the direction of the electric field formed in the combustion chamber 22 will be described in detail with reference to FIG. FIG. 3 is a schematic view of the combustion chamber 22 as viewed from the fuel injection valve 25 side. 3 shows the direction of the electric field when the wall surface electrode 262 is a positive electrode and the center electrode 35 is a negative electrode.

  In the combustion chamber 22, a swirl flow is formed to promote the combustion of fuel. Specifically, as shown by a one-dot chain line arrow F <b> 1 in FIG. 3, fuel and air flow in the circumferential direction around the center φ of the cylinder 20. The direction of a one-dot chain line arrow F1 at the tip 263 of the wall surface electrode 262 at this time is indicated by a white arrow A1. The size of the white arrow A1 represents the speed of the swirl flow of fuel.

  In the combustion stroke, when the fuel burns, a flame flows in the direction of a one-dot chain line arrow F1. At this time, an electric field represented by a two-dot chain line arrow F <b> 2 is formed between the positive wall electrode 262 and the negative central electrode 35. The direction of a two-dot chain line arrow F2 at the tip 263 of the wall surface electrode 262 at this time is indicated by a white arrow A2. That is, the electric field formed between the wall surface electrode 262 and the center electrode 35 is formed toward the radial direction of the swirl flow. The size of the white arrow A2 represents the strength of the electric field.

  The electric field formed between the wall electrode 262 and the center electrode 35 is formed so as to bend the flame inwardly. This will be described with reference to the white arrows A1 and A2 in FIG. 3 and the white arrows A3, which is a combination of the white arrows A1 and A2, and the flow of the flame in the state where the electric field is not formed (the white arrows). When an electric field (white arrow A2) acts on the arrow A1), the flame is bent in the direction of the white arrow A3. As a result, the flame flow in the combustion stroke is in a direction that does not face the flame flow in the state where the electric field is not formed (one-dot chain line arrow F1) and away from the inner wall surface 261 that forms the combustion chamber 22. Flow (dotted arrow F3).

  Further, in the engine 1, the fuel injection of the fuel injection valve 25 is performed a plurality of times. Specifically, the fuel injection stage includes a main injection stroke in which the largest amount of fuel is injected, a pilot injection stroke in which a relatively small amount of fuel is injected before the main injection stroke, a pre-injection stroke, and a main injection stroke. Are divided into an after injection stroke and a post injection stroke in which a relatively small amount of fuel is injected. In the engine 1, during the pilot injection stroke and the pre-injection stroke, an electric field is formed from the center of the combustion chamber toward the inner wall surface of the cylinder liner portion by using the central electrode as a positive electrode and the wall surface electrode as a negative electrode. Further, during the main injection stroke, an electric field directed from the inner wall surface of the cylinder liner portion toward the center of the combustion chamber is formed by using the central electrode as a negative electrode and the wall electrode as a positive electrode.

  In the combustion stroke, the piston 30 having moved to the bottom dead center after the fuel in the combustion chamber 22 burns moves toward the top dead center. At this time, the exhaust valve 48 is opened, and the exhaust from the combustion chamber 22 is discharged to the exhaust passage 421 by the piston 30 toward the top dead center (exhaust stroke).

  In general, it is known that a flame generated in a combustion stroke of an internal combustion engine has a positive electrode property and behaves so as to repel the positive electrode in an electric field and approach the negative electrode. Therefore, in the engine 1 according to the first embodiment, four wall surfaces provided on the four central electrodes 35 provided on the end of the fuel injection valve 25 and the inner wall surface 261 of the cylinder liner portion 26 in the combustion stroke. An electric field is formed between the electrode 262 and the electrode 262. This electric field changes the flame flow without facing the flame flow caused by the swirl flow of fuel in the combustion chamber 22. Specifically, if the four wall electrodes 262 are positive and the four central electrodes 35 are negative, the flame separates from the inner wall 261 of the cylinder liner portion 26. When the flame is separated from the inner wall surface 261, a gas layer such as air is formed between the cylinder liner portion 26 and the flame, and the combustion heat of the flame is hardly transmitted to the cylinder liner portion 26. Thereby, the amount of flame combustion heat released to the outside of the cylinder 20 is reduced, and the combustion heat released outside through the inner wall of the combustion chamber 22 with respect to the flame combustion heat, that is, the cooling loss is reduced. can do. Therefore, the thermal efficiency of the engine 1 can be improved.

Further, immediately after the engine 1 is started, the control unit 50 sets the center electrode 35 to the positive electrode and the wall surface electrode 262 to the negative electrode. As a result, the flame having the positive electrode property approaches the inner wall surface 261 of the cylinder liner portion 26 and the heat of the flame is easily transmitted to the inner wall surface 261, so that the temperature of the cylinder 20 rises quickly. When the temperature of the piston 30 or the cylinder 20 rises, the engine coolant and the engine oil quickly rise to the predetermined temperatures. Thereby, the startability of the engine 1 can be improved. Specifically, the amount of CO, HC, and PM in the exhaust is reduced, and the fuel consumption after starting can be reduced.
Further, when the combustion heat of the flame is quickly transmitted to the piston 30 and the cylinder 20 and the engine 1 is sufficiently warmed and the operation state of the engine 1 is stabilized, the control unit 50 sets the central electrode 35 to the negative electrode and the wall surface electrode 262 to the positive electrode. To. As a result, the flame is separated from the inner wall surface 261, and the heat of the flame is hardly transmitted to the inner wall surface 261, so that the cooling loss is reduced. Therefore, in the engine 1 according to the first embodiment, the operating state of the engine 1 can be quickly stabilized by changing the polarities of the center electrode 35 and the wall surface electrode 262.

  Further, in the fuel injection by the fuel injection valve 25, during the pilot injection stroke and the pre-injection stroke, an electric field is formed from the center of the combustion chamber toward the inner wall surface of the cylinder liner portion, and is generated by combustion in the pilot injection stroke and the pre-injection stroke. Will spread a small flame that will be. Further, during the main injection stroke, an electric field is formed from the inner wall surface of the cylinder liner portion toward the center of the combustion chamber, and a large flame generated by combustion in the main injection stroke is separated from the inner wall surface 261. Thereby, cooling loss can be reduced while efficiently performing combustion in the combustion chamber 22.

  Particulate matter generated in the combustion stroke has a positive or negative charge. When an electric field is formed between the center electrode 35 and the wall surface electrode 262, the particulate matter having a positive or negative charge is attracted to the center electrode 35 or the wall surface electrode 262 and is confined in the combustion chamber 22. Thereby, the amount of particulate matter contained in the exhaust gas can be reduced.

  Further, unburned substances such as soot adhering to the central electrode 35 and the wall surface electrode 262 can be burned by a high voltage applied between the central electrode 35 and the wall surface electrode 262. Moreover, the property of the deposit can be detected by the current value.

(Second Embodiment)
Next, an internal combustion engine according to a second embodiment of the present invention will be described with reference to FIGS. The second embodiment is different from the first embodiment in that two electrodes are provided in the cylinder head portion. In addition, the same code | symbol is attached | subjected to the site | part substantially the same as 1st Embodiment, and description is abbreviate | omitted.

  The engine 2 according to the second embodiment is, for example, an engine that performs diffusion combustion using light oil as fuel. The engine 2 is provided with a fuel injection valve 252 substantially at the center of the cylinder head 24, as shown in FIG.

  The fuel injection valve 252 has four injection holes 253 for injecting light oil into the combustion chamber 22 at equal intervals in the circumferential direction (see FIG. 5). The fuel injection valve 252 has a charging unit 251 that charges the fuel positively or negatively. The fuel injection valve 252 as “fuel supply means” injects the fuel charged by the charging unit 251 as “charging means” into the combustion chamber 22.

  A first head electrode 242 and a second head electrode 243 are provided on the inner wall surface 241 of the cylinder head 24 of the engine 2. In the engine 1 according to the second embodiment, as shown in FIG. 5 which is a schematic view of the combustion chamber 22 as viewed from the piston 30 side, four first head part electrodes 242 and four second head part electrodes. 243 is provided. The inner wall surface 241 corresponds to an “inner wall forming a combustion chamber” recited in the claims.

  The first head portion electrode 242 is provided at substantially the center of the region surrounded by the alternate long and short dash line C indicating the spread of the fuel injected from the injection hole 253. Specifically, the first head electrode 242 is provided in the vicinity of the fuel ignition point. The first head portion electrode 242 is insulated from the cylinder head portion 24 and can have a different potential from the inner wall surface 241 and the second head portion electrode 243. The first head portion electrode 242 is provided so as to protrude from the inner wall surface 241 of the cylinder head portion 24 in the direction of the piston 30. The first head electrode 242 has either a positive polarity or a negative polarity when fuel is injected from the injection hole 253. The first head portion electrode 242 corresponds to “potential difference forming means” recited in the claims.

  The second head portion electrode 243 is provided so as to be positioned in the radially inner direction from the first head portion electrode 242 and between the adjacent first head portion electrodes 242. The second head part electrode 243 is provided to have the same potential as the cylinder head part 24. The second head portion electrode 243 is provided so as to protrude from the inner wall surface 241 of the cylinder head portion 24 in the direction of the piston 30, and the length protruding from the inner wall surface 241 is longer than the first head portion electrode 242. (Fig. 4). The second head electrode 243 has either a positive polarity or a negative polarity when fuel is injected from the injection hole 253. The second head electrode 243 corresponds to “inner wall forming a combustion chamber” and “first protrusion” recited in the claims.

  In the combustion stroke of the engine 2, when the fuel injection valve 252 injects fuel into the combustion chamber 22, the fuel spreads in a region surrounded by the alternate long and short dash line C. When combustion starts near the position where the first head portion electrode 242 is located, the flame flows in all directions of the region surrounded by the one-dot chain line C around the vicinity where the first head portion electrode 242 is located. A flame flows along the fuel which spreads in the direction injected from the hole 253, that is, in the direction of the solid line arrow F4.

  In the engine 2 according to the second embodiment, an electric field is formed in the direction from the first head electrode 242 to the second head electrode 243 by the first head electrode 242 serving as the positive electrode and the second head electrode 243 serving as the negative electrode. To do. Thereby, the flame flowing in the radial direction from the vicinity of the first head electrode 242 further flows in the direction of the dotted arrow F5 by the electric field. Further, since the flame extends in a direction away from the inner wall surface 261 of the cylinder liner portion 26, the amount of combustion heat of the flame released to the outside of the cylinder 20 is reduced, and the cooling loss can be reduced. Therefore, the engine 2 according to the second embodiment has the same effects as the first embodiment.

  Further, the engine 2 has an action of spreading the flame in the direction opposite to the fuel injection direction. For this reason, the air in the vicinity of the nozzle hole 253, which is relatively difficult to use at the time of combustion, can be used for generating a flame. Therefore, the combustion efficiency of the engine 2 can be improved.

  Further, the fuel injection valve 252 can perform so-called “electrostatic spraying” in which charged fuel is directly injected into the combustion chamber 22. The charged fuel changes the position of the cylinder head portion 24 relative to the inner wall surface 241 in accordance with the direction of the electric field formed by the first head portion electrode 242 and the second head portion electrode 243. For example, the positively charged fuel repels the inner wall surface 241 having the positively charged second head electrode 243 and moves away from the inner wall surface 241. Further, the negatively charged fuel moves in a direction approaching the inner wall surface 241 having the positively charged second head electrode 243. Thus, by charging the fuel, the position with respect to the cylinder head portion 24 can be controlled, and the position of the flame can be controlled.

(Third embodiment)
Next, an internal combustion engine according to a third embodiment of the present invention will be described with reference to FIGS. The third embodiment differs from the first embodiment in that an electric field is formed between the potential difference forming means and the intake and exhaust valves. In addition, the same code | symbol is attached | subjected to the site | part substantially the same as 1st Embodiment, and description is abbreviate | omitted.

  In the engine 3 according to the third embodiment, as shown in FIG. 6, the intake valve 18 and the exhaust valve 48 are electrically connected to the booster 56 of the controller 50.

  A central electrode 36 is provided in the cylinder head portion 24. The center electrode 36 has an electrode portion 361 that does not have a protrusion at the tip. The cross-sectional shape of the electrode part 361 is, for example, an elliptical shape. The electrode portion 361 is formed such that the inner wall surface closest to the electrode portion 361 among the inner wall surfaces forming the combustion chamber 22 becomes the intake valve end surface 181 of the intake valve 18 and the exhaust valve end surface 481 of the exhaust valve 48. 6 and 7, the fuel injection valve provided in the cylinder head portion 24 is omitted for convenience of explanation. The central electrode 36 corresponds to “potential difference forming means” described in the claims. The intake valve end surface 181 and the exhaust valve end surface 481 correspond to an “inner wall forming a combustion chamber” recited in the claims.

  When the intake valve 18 and the exhaust valve 48 are positive, the control unit 50 sets the central electrode 36 as a negative electrode. When the intake valve 18 and the exhaust valve 48 are negative electrodes, the central electrode 36 is a positive electrode.

  The engine 3 forms an electric field between the intake valve 18 and the exhaust valve 48 and the central electrode 36 in the combustion stroke. In particular, when the intake valve 18 and the exhaust valve 48 are positive and the central electrode 36 is negative, an electric field in the direction of a dotted arrow F6 is formed as shown in FIG. Due to this electric field, the flame in the combustion chamber 22 is separated from the inner wall surface 241 of the cylinder head portion 24 and remains near the center of the combustion chamber 22. Thereby, the combustion heat of the flame discharged | emitted outside via the cylinder head part 24 can be decreased. Therefore, the engine 3 according to the third embodiment has the same effects as the first embodiment.

(Fourth embodiment)
Next, an internal combustion engine according to a fourth embodiment of the present invention will be described with reference to FIG. The fourth embodiment is different from the third embodiment in that an electric field is formed between the potential difference forming means and the piston. In addition, the same code | symbol is attached | subjected to the site | part substantially the same as 3rd Embodiment, and description is abbreviate | omitted.

  In the engine 4 according to the fourth embodiment, a substantially flat plate electrode 31 is provided on the piston surface 301 of the piston 30. The flat electrode 31 is provided integrally with the piston 30 and is electrically connected to the booster 56 of the controller 50 via the piston 30. The flat electrode 31 corresponds to an “inner wall forming a combustion chamber” recited in the claims.

  When the flat electrode 31 is used as a positive electrode, the control unit 50 uses the central electrode 36 as a negative electrode. When the flat electrode 31 is a negative electrode, the central electrode 36 is a positive electrode.

  In the engine 4, an electric field is formed between the center electrode 36 and the plate electrode 31 in the combustion stroke. In particular, when the central electrode 36 is a negative electrode and the piston 30 and the plate electrode 31 are positive electrodes, an electric field in the direction of a dotted arrow F7 is formed as shown in FIG. Due to this electric field, the flame in the combustion chamber 22 is separated from the piston surface 301 of the piston 30 and remains in the vicinity of the center of the combustion chamber 22. Thereby, the combustion heat of the flame discharged | emitted outside via the piston 30 can be decreased. Therefore, the engine 4 according to the fourth embodiment has the same effects as the first embodiment.

(Fifth embodiment)
Next, an internal combustion engine according to a fifth embodiment of the present invention will be described with reference to FIGS. The fifth embodiment is different from the fourth embodiment in that a protruding electrode is provided on the piston surface. In addition, the same code | symbol is attached | subjected to the site | part substantially the same as 4th Embodiment, and description is abbreviate | omitted.

  In the engine 5 according to the fifth embodiment, the piston surface 301 forming the combustion chamber 22 of the piston 30 is formed in a concave shape as shown in FIG. In the combustion chamber 22 of the engine 5, the concave piston surface 301 forms a tumble flow in which the fuel injected by the fuel injection valve is involved. Plural protruding electrodes 311 are provided on the piston surface 301. In the engine 5, four protruding electrodes 311 are provided. The protruding electrode 311 is formed to extend in the direction of the cylinder head portion 24. The protruding electrode 311 is electrically connected to the booster 56 of the controller 50 via the piston 30. The protruding electrode 311 corresponds to “inner wall forming a combustion chamber” and “second protrusion” described in the claims.

  An electrode portion 362 having a plurality of protrusions 363 is provided at the tip of the central electrode 36 provided in the cylinder head portion 24. The protrusion 363 is formed so that the distance from the protruding electrode 311 is the shortest compared to the piston surface 301. In FIG. 9, for convenience of explanation, the fuel injection valve provided in the cylinder head portion 24 is omitted.

  When the projecting electrode 311 is a positive electrode, the controller 50 sets the central electrode 36 as a negative electrode. When the protruding electrode 311 is a negative electrode, the central electrode 36 is a positive electrode.

  In the engine 5, an electric field is formed between the center electrode 36 and the protruding electrode 311 in the combustion stroke. In particular, when the protruding electrode 311 is a positive electrode and the central electrode 36 is a negative electrode, an electric field in the direction of a dotted arrow F8 is formed as shown in FIG. With this electric field, as shown in FIG. 10, a one-dot chain line arrow indicating a fuel flow in a state where an electric field is formed with respect to a two-dot chain line arrow F0 indicating a fuel flow in a state where no electric field is formed. It leaves | separates from the piston surface 301 like F9. Thus, when the fuel is combusted in the combustion stroke, the flame flows away from the piston surface 301 as in the flow F9. Therefore, the combustion heat of the flame released to the outside through the piston 30 can be reduced, and the engine 5 according to the fifth embodiment has the same effect as the first embodiment.

(Other embodiments)
(A) In the above-described embodiment, the engine is a direct injection type four-stroke engine using light oil as fuel. However, the type of fuel and the type of engine are not limited to this. In the case of a diesel engine, it may be a compression ignition type engine or an engine equipped with a glow plug. Further, an engine using gasoline as fuel may be used. In the case of a gasoline engine, it may be a direct-injection type gasoline engine that directly injects gasoline into the combustion chamber, a PFI type that injects gasoline into the intake passage, or a gas engine that uses natural gas as fuel. For example, an engine using a mixed fuel of alcohol and gasoline as fuel may be used. A two-stroke engine may also be used.

  (A) In the first embodiment, the protruding wall surface electrode is provided on the inner wall of the cylinder liner portion. However, the structure which provides a wall surface electrode is not limited to this. An insulating film is formed on the inner wall of the cylinder liner portion, and the electric resistance is partially changed by making the thickness of the insulating film at the portion where the electric field is formed thinner than the thickness of the insulating film at the other portion, You may make it form an electric field between the site | parts with small electrical resistance on the inner wall of a cylinder liner part.

  (C) In the above-described embodiment, the control unit calculates the optimum voltage value and current value for forming an electric field in the combustion chamber based on the opening degree of the throttle valve, the crank angle, and the exhaust gas temperature. However, the parameters based on when the control unit calculates the optimum voltage value and current value are not limited to this. For example, the pressure in the combustion chamber used when calculating the optimum voltage value and current value may be calculated based on the accelerator opening of the accelerator device, the EGR amount based on the map, the compression ratio, and the like. Further, the temperature of the combustion chamber used when calculating the optimum voltage value and current value may be calculated based on the EGR amount based on the map.

  (D) In the second embodiment, the fuel injected by the fuel injection valve is charged. However, the fuel may not be charged. Further, in the first embodiment, the third, fourth, and fifth embodiments, the fuel may be charged.

  As mentioned above, this invention is not limited to such embodiment, It can implement with a various form in the range which does not deviate from the summary.

1, 2, 3, 4, 5 ... engine (internal combustion engine),
181 ... Inlet valve end face (inner wall forming a combustion chamber),
20 ... Cylinder,
22 ... combustion chamber,
241 ... inner wall surface (inner wall forming a combustion chamber),
242 ... 1st head part electrode (potential difference forming means),
243 ... 2nd head part electrode (inner wall forming combustion chamber),
25, 252 ... Fuel injection valve (fuel supply means),
261 ... inner wall surface (inner wall forming a combustion chamber),
262 ... Wall electrode (inner wall forming combustion chamber),
30 ・ ・ ・ Piston,
31 ... Flat plate electrode (inner wall forming combustion chamber),
311 ... Projection electrode (inner wall forming combustion chamber),
35, 36 ... central electrode (potential difference forming means),
481... Exhaust valve end face (inner wall forming a combustion chamber).

Claims (10)

A reciprocating piston (30);
A cylinder (20) having a combustion chamber (22) for accommodating the piston and having a volume variable by reciprocating movement of the piston;
Fuel supply means (25, 252) provided at the center of the cylinder head portion (24) of the cylinder and for supplying fuel to the combustion chamber;
The fuel supply means is provided in the cylinder head near the ignition point of fuel injected into the combustion chamber, and is different from inner walls (181, 241, 243, 261, 262, 31, 311 and 481) forming the combustion chamber. Potential difference forming means (242, 35,...) For forming an electric field between the inner wall and the inner wall so as not to oppose the flow direction of the flame generated when the fuel in the combustion chamber is burned. 36)
A first protrusion (243) that is inwardly of the potential difference forming means on the inner wall and is provided between the potential difference forming means adjacent to each other, and forms an electric field with the potential difference forming means;
An internal combustion engine comprising: 2. The internal combustion engine according to claim 1 , wherein the potential difference forming means and the first protrusions are provided in a number corresponding to the number of injection holes (253) of the fuel supply means.   The internal combustion engine according to claim 1, wherein the potential difference forming means (36) forms an electric field between the piston and the piston. The internal combustion engine according to claim 3 , wherein the piston has a second protrusion (311) that forms an electric field with the potential difference forming means on a piston surface (301) that forms the combustion chamber. Charging means (251) for charging fuel supplied to the combustion chamber;
The internal combustion engine according to any one of claims 1 to 4 , wherein the fuel supply means supplies charged fuel to the combustion chamber. In any one of claims 1 to 5, characterized in that a control unit (50) for controlling the time of forming the strength and the electric field of the electric field formed between the electric potential difference forming means and the inner wall The internal combustion engine described. A reciprocating piston (30);
A cylinder (20) having a combustion chamber (22) for accommodating the piston and having a volume variable by reciprocating movement of the piston;
Fuel supply means (25, 252) provided at the center of the cylinder head portion (24) of the cylinder and for supplying fuel to the combustion chamber;
The fuel supply means is provided in the cylinder head near the ignition point of fuel injected into the combustion chamber, and is different from inner walls (181, 241, 243, 261, 262, 31, 311 and 481) forming the combustion chamber. Potential difference forming means (242, 35,...) For forming an electric field between the inner wall and the inner wall so as not to oppose the flow direction of the flame generated when the fuel in the combustion chamber is burned. 36)
A first protrusion (243) that is inwardly of the potential difference forming means on the inner wall and is provided between the potential difference forming means adjacent to each other, and forms an electric field with the potential difference forming means;
A control unit (50) for controlling the strength of the electric field formed between the potential difference forming means and the inner wall and the time for forming the electric field;
An internal combustion engine control method comprising:
The control unit forms an electric field in the combustion chamber during at least one of a compression stroke or a combustion stroke, and in a pre-injection stroke for injecting fuel into the combustion chamber, the center of the combustion chamber is applied to the inner wall. Forming an electric field directed toward the center of the combustion chamber from the inner wall during a main injection stroke in which more fuel is injected into the combustion chamber after the pre-injection stroke than in the pre-injection stroke. A control method of an internal combustion engine characterized by the above. 8. The method of controlling an internal combustion engine according to claim 7 , wherein the control unit forms an electric field from the center of the combustion chamber toward the inner wall for a predetermined time from the start of the internal combustion engine. The control method of the internal combustion engine according to claim 7 or 8 , wherein the control unit forms an electric field from the inner wall toward the center of the combustion chamber after a predetermined time has elapsed since the start of the internal combustion engine. . The control of the internal combustion engine according to any one of claims 7 to 9 , wherein the control unit increases a voltage applied to the potential difference forming unit as the pressure of the combustion chamber increases in a compression stroke. Method.

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