JP2006200388A - Internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal combustion engine improving lean limit. <P>SOLUTION: A conductive part 21 is put into contact with an intake valve 11 and an exhaust valve 12. The conductive part 21 is connected to a high voltage power source part 20, and the high voltage power source part 20 is connected to a connecting rod 5. The connecting rod 5 is electrically connected to a piston 4 via a connecting pin 6. Consequently, electric potential difference arises between a valve surface 14 and the piston 4 and electric field is generated when high voltage electric potential of different polarity is applied to the conductive part 21 and the connecting rod 5 respectively at the high voltage power source part 20. Consequently, corona discharge arises when fuel positioned in the electric field burns in combustion of fuel in a combustion chamber 10. Flame propagation speed is improved by corona discharge and combustion is promoted. As a result, lean limit can be improved. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an internal combustion engine. In particular, the present invention relates to an internal combustion engine capable of stabilizing combustion.

  In the conventional internal combustion engine, since exhaust gas after combustion may affect air pollution, various means are used for purification of exhaust gas. For example, in Patent Document 1, denitration is performed in a combustion chamber by forming a discharge field in a cylinder block. For this reason, since denitration can be performed at high pressure, the apparatus related to denitration can be made compact.

JP-A-5-321641

  However, in recent internal combustion engines, in order to further purify exhaust gas and improve fuel consumption, internal combustion engines that perform so-called lean combustion, which reduces the amount of fuel with respect to air during combustion, are gradually increasing. By performing lean combustion in this way in an internal combustion engine, the amount of fuel at the time of combustion is reduced, so that fuel efficiency can be improved, and defective combustion of fuel can be reduced, so exhaust gas is purified. It becomes easy. However, in lean combustion, since the density of fuel in the air-fuel mixture taken into the combustion chamber is small, the flame propagation speed during combustion tends to decrease. Thus, since the flame propagation speed is reduced in lean combustion, the fuel cannot be made thinner than a predetermined mixing ratio, that is, it cannot be made lean, and the reduction in the flame propagation speed determines the lean limit. . As described above, in the conventional internal combustion engine, when the lean combustion is performed, the flame propagation speed is lowered, so even if it is desired to improve the fuel consumption, it is not possible to set the mixture ratio in a leaner direction. was there.

  The present invention has been made in view of the above, and an object thereof is to provide an internal combustion engine capable of improving the lean limit.

  In order to solve the above-described problems and achieve the object, an internal combustion engine according to the present invention is an internal combustion engine that burns fuel by igniting fuel in a combustion chamber with a spark plug, and when the fuel burns in the combustion chamber. An electric field generating means for generating an electric field at a position where a flame caused by the combustion of the fuel propagates and generating a corona discharge at least when the flame propagates in the electric field is provided.

  In the present invention, an electric field generating means for generating an electric field in the combustion chamber is provided. This electric field created by the electric field generating means is created at a position where the flame caused by the combustion propagates when the fuel burns in the combustion chamber. At least when the flame caused by the combustion of the fuel propagates into the electric field, Corona discharge occurs. For this reason, since a flame is disturb | confused and combustion is accelerated | stimulated, a flame propagation speed improves. Thereby, even when the ratio of the fuel to the air is reduced and the mixing ratio is in the lean direction, the entire fuel in the combustion chamber can be burned. As a result, the lean limit can be improved.

  In the internal combustion engine according to the present invention, the combustion chamber is constituted by a cylinder head provided with an intake / exhaust valve, a piston faces the combustion chamber, and the electric field generating means includes the intake / exhaust The electric field is generated by generating a potential difference between the intake / exhaust valve and the piston while being connected to the valve and the piston.

  In the present invention, an electric field generating means is connected to the intake / exhaust valve and the piston, and an electric field is created by generating a potential difference therebetween. For this reason, an electric field can be created in most of the combustion chamber. As a result, the flame when the fuel burns more reliably propagates in the electric field, so that the flame is more reliably disturbed by the corona discharge, and the flame propagation speed can be improved. As a result, the lean limit can be improved more reliably.

  Further, in the internal combustion engine according to the present invention, the combustion chamber has an auxiliary combustion chamber in which the ignition plug is provided while the combustion chamber is formed in an electrically independent two-divided structure, and the electric field generating means The electric field is generated in the sub-combustion chamber by generating a potential difference between the parts that are connected to the sub-combustion chamber and have the two-part structure.

  In this invention, an electric field can be created around the spark plug by creating an electric field in the auxiliary combustion chamber provided with the spark plug. For this reason, when the mixture of fuel and air is ignited by the spark plug, the flame propagation speed immediately after ignition can be improved and combustion can be facilitated, so that misfire immediately after ignition can be suppressed. As a result, the fuel can be burned more reliably.

  The internal combustion engine according to the present invention is characterized in that fuel is directly injected into the combustion chamber by a fuel injection means, and the fuel injected by the fuel injection means is collected in the sub-combustion chamber.

  In the present invention, an electric field is created in the auxiliary combustion chamber provided with the spark plug, and the fuel injected by the fuel injection means is collected in the auxiliary combustion chamber. For this reason, most of the fuel injected into the combustion chamber is located in the electric field of the sub-combustion chamber. Therefore, when the fuel is ignited by the ignition part of the spark plug, the flame propagation speed of most of the fuel is improved. Can be made. Thereby, the misfire immediately after ignition of fuel can be suppressed more reliably. As a result, the fuel can be burned more reliably.

  Further, in the internal combustion engine according to the present invention, the combustion chamber is configured by a cylinder head, a piston faces the combustion chamber, and the electric field generating means is connected to the cylinder head and the piston. And the electric field is generated by generating a potential difference between the cylinder head and the piston.

  In the present invention, the electric field generating means is connected to the cylinder head and the piston. Among these, since the cylinder head is a stationary component, the electric field generating means can be easily connected. In addition, since the cylinder head constitutes a combustion chamber, an electric field can be generated in most of the combustion chamber by connecting an electric field generating means to the cylinder head. Thereby, since the flame at the time of fuel combustion propagates more reliably in the electric field, the flame propagation speed can be improved more reliably. As a result, the lean limit can be easily and more reliably improved.

  Further, in the internal combustion engine according to the present invention, the electric field generating means generates a potential difference between the vicinity of the outer peripheral portion of the combustion chamber forming portion which is a portion forming the combustion chamber of the cylinder head and the piston. The electric field is generated.

  In the present invention, the electric field generating means generates a potential difference between the vicinity of the outer peripheral portion of the combustion chamber forming portion and the piston, thereby improving the flame propagation speed of the portion where the temperature is likely to decrease. In other words, the piston is provided with a plurality of piston rings, but it is located in the space surrounded by the opposed surfaces of the piston ring closest to the cylinder head, the cylinder block in which the piston is installed, and the piston. The air-fuel mixture of fuel and air tends to come into contact with the piston and cylinder block and the temperature tends to decrease. For this reason, it is difficult for the fuel in this portion to burn, but by generating a potential difference between the outer peripheral portion of the combustion chamber forming portion and the piston, an electric field is provided in this portion and corona discharge is easily generated. be able to. Thereby, the flame propagation speed of this space can be improved and the part with a bad combustion state can be reduced. As a result, the lean limit can be improved more reliably.

  Further, the internal combustion engine according to the present invention is characterized in that the spark plug is located in the vicinity of a portion of the cylinder head where the electric field generating means is provided.

  In this invention, by positioning the spark plug in the vicinity of the electric field generating means, the fuel can be ignited by the spark plug and the flame immediately after ignition can be propagated in the electric field. Thereby, since the flame propagation speed immediately after ignition can be improved and combustion can be facilitated, misfire immediately after ignition can be suppressed. As a result, the fuel can be burned more reliably.

  The internal combustion engine according to the present invention has an effect that the lean limit can be improved.

  Embodiments of an internal combustion engine according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements in the following embodiments include those that can be easily replaced by those skilled in the art or those that are substantially the same. In the following description, an internal combustion engine having a plurality of cylinders is described, but the number of cylinders of the internal combustion engine may be single.

  FIG. 1 is a schematic diagram showing a configuration of an internal combustion engine according to Embodiment 1 of the present invention. An internal combustion engine 1 shown in the figure has a plurality of cylinders, and each cylinder has a cylinder block 2 and a cylinder head 3 in which a combustion chamber 10 is formed. A piston 4 is disposed inside the cylinder block 2, and the cylinder head 3 is fixed to the end of the cylinder block 2 on the side toward the top dead center via a gasket 7. Yes. The gasket 7 is an insulator that blocks the flow of electricity.

  Further, a portion of the piston 4 on the cylinder head 3 side faces the combustion chamber 10, and a connecting rod 5 is disposed on the opposite side of the piston 4 on the side facing the combustion chamber 10 side. Yes. The connecting rod 5 is supported at its piston 4 side end so as to be rotatable with the piston 4 by a connecting pin 6. The other end of the connecting rod 5 is rotatably supported by a crankshaft (not shown).

  The cylinder head 3 is provided with an ignition plug 15 and an intake / exhaust valve. Among these, the intake / exhaust valve includes an intake valve 11 and an exhaust valve 12, and the intake valve 11 is provided to open and close an intake passage (not shown) communicating with the combustion chamber 10. The exhaust valve 12 is provided so as to open and close an exhaust passage communicating with the combustion chamber 10. The spark plug 15 is provided between the intake valve 11 and the exhaust valve 12, and further includes an ignition unit 16 that performs arc discharge when a high voltage is applied. The spark plug 15 is provided so that the ignition unit 16 is located in the combustion chamber 10.

  Both the intake valve 11 and the exhaust valve 12 have a valve stem 13. Around the both valve stems 13, there is provided a conductive portion 21 fixed to the cylinder head 3 and in contact with the valve stem 13 so as to be slidable. The conductive portion 21 also serves as a stem guide and is formed as a part of the electric field generating means. Similarly to the conductive part 21, the conductive part 21 is provided as a part of the electric field generating means, and is connected to the high-voltage power supply part 20 that generates a high-voltage power supply. The high voltage power supply unit 20 is also connected to the connecting rod 5. The intake valve 11 and the exhaust valve 12 are entirely made of metal, and the connecting rod 5, the connecting pin 6, and the piston 4 are all made of metal.

  For these reasons, the valve surface 14 which is the surface of the intake valve 11 and the exhaust valve 12 on the combustion chamber 10 side is electrically connected to the conductive portion 21, and the piston 4 is electrically connected to the connecting rod 5. Therefore, the high voltage supplied from the high voltage power supply unit 20 is provided so that a high potential difference can be generated between the valve surface 14 and the piston 4. The gasket 7 is interposed between the cylinder head 3 provided with the conductive portion 21 and the cylinder block 2 in which the piston 4 and the connecting rod 5 are provided, and the gasket 7 becomes an insulator. Therefore, the cylinder head 3 and the cylinder block 2 are not directly electrically connected.

  The internal combustion engine 1 according to the first embodiment is configured as described above, and the operation thereof will be described below. The internal combustion engine 1 is operated by repeatedly performing an intake stroke, a compression stroke, a combustion stroke, and an exhaust stroke by repeating the reciprocating motion of the piston 4 in the cylinder block 2. The outline of each stroke is as follows. In the intake stroke, the exhaust valve 12 is closed, the intake valve 11 is opened, and a mixture of fuel and air is taken into the combustion chamber 10 from the intake passage, and in the compression stroke, the intake valve 11 is also closed and burned. The air-fuel mixture taken into the chamber 10 is compressed. In the combustion stroke, a high voltage current is applied to the spark plug 15 and an arc discharge is generated in the ignition part 16 of the spark plug 15, whereby the compressed air-fuel mixture is ignited and the fuel in the air-fuel mixture burns. In the exhaust stroke, the exhaust valve 12 is opened, and the exhaust gas after combustion is discharged in the direction of the exhaust passage. In the internal combustion engine 1, the air-fuel mixture taken into the combustion chamber 10 during the intake stroke is a lean air-fuel mixture in which the fuel to air ratio is lower than the stoichiometric fuel ratio depending on the operating state. In some cases, so-called lean combustion may be performed in the combustion stroke.

  During these strokes, the high-voltage power supply unit 20 includes the conductive portion 21 and the conductive portion 21 in the range of −60 ° to + 60 ° in the crank angle when the crankshaft rotates with reference to the position of the top dead center of the piston 4 in the compression stroke. The connecting rod 5 is continuously applied with potentials having different polarities. For this reason, the valve surface 14 and the piston 4 are connected to the high voltage power supply unit 20 with a high voltage having a different polarity via the valve stem 13 in contact with the conductive part 21 and the connecting pin 6 that connects the connecting rod 5 and the piston 4. The potential continues to be applied. That is, one of the valve face 14 and the piston 4 is given a positive (+) high voltage potential, and the other is given a negative (-) high voltage potential. Thereby, an electric potential difference arises between the valve surface 14 and the piston 4, and an electric field is created. The voltage applied to the valve surface 14 and the piston 4 by the high voltage power supply unit 20 is several tens of kV or less.

  As described above, when the air-fuel mixture is ignited by the spark plug 15 in the state where the electric field is generated between the valve face 14 and the piston 4 by the high-voltage power supply unit 20, the fuel in the air-fuel mixture burns, and this combustion The flame due to propagates in the electric field. For this reason, the fuel at the time of combustion burns while the flame propagates in the electric field. Since this electric field is created by a high potential difference between the valve surface 14 and the piston 4, a corona discharge is generated between the valve surface 14 and the piston 4 when the flame propagates in the electric field. To do. When corona discharge occurs in this way, current flows through the air-fuel mixture or flame in the electric field due to corona discharge, so that flow occurs in the air-fuel mixture and the flame is disturbed. When the flame is disturbed in this way, combustion is promoted compared to the case where there is no air-fuel mixture flow, and the combustion speed, that is, the flame propagation speed is improved. For this reason, even when lean mixture with a small fuel ratio is taken into the combustion chamber 10 and lean combustion is performed, the fuel in the mixture becomes easy to burn.

  Here, the corona discharge refers to a phenomenon in which a current of several mA or less is discharged from a conductor to which a high voltage (several tens of kV or less) is applied. In other words, corona discharge refers to controlling the voltage so that a spark does not fly and causing a current of about several mA to flow in the air. For this reason, an electric field is created by applying a high voltage of several tens of kV or less to the valve face 14 and the piston 4 as described above, and the current flowing in the electric field by the corona discharge generated in this electric field is about several μA. ing.

  The internal combustion engine 1 described above is provided with a high voltage power supply unit 20 and a conductive unit 21 as an electric field generating means for generating an electric field in the combustion chamber 10. The electric field generated in the combustion chamber 10 by the high-voltage power supply unit 20 and the conductive unit 21 is generated at a position where a flame caused by combustion propagates when the fuel burns in the combustion chamber 10. For this reason, when the fuel burns, the flame at the time of combustion propagates in the electric field, and in the electric field, corona discharge is generated by this flame. As described above, since the corona discharge is generated in the electric field, a flow is generated in the air-fuel mixture, the flame is disturbed, the combustion is promoted, and the flame propagation speed is improved. Therefore, even when the ratio of fuel to air is reduced and the mixing ratio is in the lean direction, the flame propagation speed can be improved by generating corona discharge, so that the entire fuel in the combustion chamber 10 is burned. Can do. As a result, the lean limit can be improved. Note that the lean limit means that when the mixture of fuel and air is burned, if the amount of fuel is reduced with respect to the amount of air, it is burned normally without misfire. This is the limit of the air-fuel ratio that can be used.

  Further, the intake valve 11 and the exhaust valve 12 are brought into contact with a conductive portion 21 connected to the high-voltage power supply unit 20, and the piston 4 is connected to the high-voltage power supply unit 20 via the connecting pin 6 and the connecting rod 5. An electric field is created between the piston 4 and the valve face 14 by generating a potential difference between the piston 4 and the valve face 14. The piston 4 is formed with a diameter approximately equal to the inner diameter of the cylinder block 2, and the valve surface 14 of the intake valve 11 is formed to be large so that more air-fuel mixture can be taken into the combustion chamber 10, and the valve surface of the exhaust valve 12. 14 is formed large so that the exhaust gas after combustion of the fuel can be discharged earlier in the direction of the exhaust passage. As described above, since the piston 4 and the valve surface 14 occupy most of the area of the combustion chamber 10, a large electric field in the combustion chamber 10 is created by creating an electric field between the piston 4 and the valve surface 14. An electric field can be created in the part. Thereby, the flame at the time of combustion of a fuel can propagate the inside of an electric field more reliably, and can improve a flame propagation speed more reliably by corona discharge. As a result, the lean limit can be improved more reliably.

  The high-voltage power supply unit 20 is connected to the valve surface via the conductive unit 21 and the connecting rod 5 within a range of ± 60 ° in the crank angle when the crankshaft rotates with reference to the position of the top dead center of the piston 4 in the compression stroke. 14 or piston 4 is caused to have a potential difference. Since the ignition part 16 of the spark plug 15 performs arc discharge before and after the top dead center of the piston 4 in the compression stroke, the fuel in the combustion chamber 10 is ignited accordingly. Further, since the ignition of the ignited fuel ends while the pressure in the combustion chamber 10 is high, the combustion ends early after ignition. For these reasons, by creating a potential difference between the valve surface 14 and the piston 4 within the above range and creating an electric field, it is possible to more reliably propagate the flame during combustion of the fuel into the electric field, and more reliably the corona. The flame propagation speed by discharge can be improved. In addition, since the timing for generating a potential difference between the valve surface 14 and the piston 4 is limited, the energy for creating the electric field can be minimized. As a result, it is possible to more reliably improve the lean limit while suppressing energy consumption.

  Moreover, since the lean limit can be improved by generating corona discharge at the position where the flame propagates during the combustion of the fuel as described above, the mixing ratio taken into the combustion chamber 10 is made to be in a leaner direction. That is, the ratio of fuel to air can be reduced. As a result, fuel consumption can be improved, and generation of substances that affect air pollution such as NOx can be reduced.

  This internal combustion engine has substantially the same configuration as the internal combustion engine according to the first embodiment, but has a feature in that it has a sub-combustion chamber and the conductive portion is connected to the sub-combustion chamber. Since other configurations are the same as those of the first embodiment, the description thereof is omitted and the same reference numerals are given. FIG. 2 is a schematic diagram showing the configuration of the internal combustion engine according to the second embodiment of the present invention. The internal combustion engine 30 shown in the figure is provided with a sub-combustion chamber 31 formed continuously with the combustion chamber 10. The auxiliary combustion chamber 31 is provided in the cylinder head 3 and is located in a direction opposite to the direction of the piston 4 in the combustion chamber 10 with respect to the combustion chamber 10. The spark plug 15 is located in the auxiliary combustion chamber 31, and the ignition part 16 of the ignition plug 15 is located in the auxiliary combustion chamber 31. The auxiliary combustion chamber 31 is formed in a two-part structure divided in the radial direction of the piston 4, and the auxiliary combustion chamber 31 is formed by integrating the two auxiliary combustion chamber walls 32. The divided sub-combustion chamber walls 32 are electrically independent from each other, and are integrally formed in an electrically independent state.

  The conductive portion 33 provided in the internal combustion engine 30 of the second embodiment is connected to the high-voltage power supply unit 20 in the same manner as the conductive portion 21 provided in the internal combustion engine 1 of the first embodiment. Unlike the conductive portion 21 provided in one internal combustion engine 1, two conductive portions 33 having different potentials are provided. In the two conductive portions 33, one conductive portion 33 is connected to one sub-combustion chamber wall 32 of the two sub-combustion chamber walls 32. For this reason, the two sub-combustion chamber walls 32 are provided so as to be given different polarities by the conductive portion 33.

  The cylinder head 3 is provided with an injector 34 serving as fuel injection means for directly injecting fuel into the combustion chamber. The injector 34 is disposed so as to inject fuel into the combustion chamber 10. Further, the injector 34 is formed so as to inject fuel in the direction of the piston 4 when the fuel is injected into the combustion chamber 10. The piston 4 is formed with a current transformation portion 35 on the side facing the combustion chamber 10, and the injector 34 is formed so as to inject fuel in the direction of the current transformation portion 35. This current transformation part 35 is formed in the shape of the curved surface dented in the direction of the crankshaft from the surface of the piston 4 facing the combustion chamber 10. Furthermore, the curved surface of the current transformation part 35 is formed in a shape that is curved from the direction in which the injector 34 is provided toward the direction in which the auxiliary combustion chamber 31 is formed.

  The internal combustion engine 30 according to the second embodiment is configured as described above, and the operation thereof will be described below. The sub-combustion chamber 31 has a two-part structure composed of two sub-combustion chamber walls 32, and conductive parts 33 are connected to the two sub-combustion chamber walls 32, respectively. The two sub-combustion chamber walls 32 are electrically independent from each other, and are formed by the two conductive portions 33 so as to be given potentials having different polarities. For this reason, when a potential is applied to the conductive portion 33 by the high-voltage power supply unit 20, a potential difference is generated between the two auxiliary combustion chamber walls 32, and an electric field is created in the auxiliary combustion chamber 31 formed by these auxiliary combustion chamber walls 32. It is.

  Further, the high-voltage power supply unit 20 has two conductive portions 33 having different polarities in the range of −10 ° to + 10 ° in the crank angle when the crankshaft rotates with reference to the position of the top dead center of the piston 4 in the compression stroke. The potential is continuously applied and a potential difference is continuously generated between the two auxiliary combustion chamber walls 32. For this reason, the electric field of the auxiliary combustion chamber 31 is created in the range of −10 ° to + 10 ° in the crank angle when the crankshaft rotates.

  The injector 34 injects fuel into the combustion chamber 10, and the injected fuel is directed toward the current transformation portion 35 of the piston 4. Since the current transformation part 35 is formed in a shape curved from the direction in which the injector 34 is provided toward the direction in which the auxiliary combustion chamber 31 is formed, the fuel injected by the injector 34 is the current transformation part. The direction of travel is changed at 35 and is mainly directed in the direction of the auxiliary combustion chamber 31 and collected in the auxiliary combustion chamber 31.

  Since the ignition part 16 of the spark plug 15 is located in the auxiliary combustion chamber 31, when the ignition part 16 performs arc discharge, first, the fuel collected in the auxiliary combustion chamber 31 is ignited, The flame propagates from within the auxiliary combustion chamber 31. In addition, an electric field is created by the conductive portion 33 in the sub-combustion chamber 31 where the fuel is ignited by the ignition portion 16 and the flame propagates in this way. For this reason, in the auxiliary combustion chamber 31, a corona discharge is generated by the flame immediately after ignition, and the flame propagation speed in the auxiliary combustion chamber 31 is improved by the corona discharge.

  In the internal combustion engine 30 described above, the auxiliary combustion chamber 31 in which the ignition plug 15 is disposed is formed by two electrically independent auxiliary combustion chamber walls 32, and the conductive parts are further provided on the two auxiliary combustion chamber walls 32, respectively. By connecting 33, an electric field is created in the auxiliary combustion chamber 31. For this reason, the flame propagation speed immediately after ignition of fuel can be improved, combustion can be promoted, and misfiring immediately after ignition of fuel can be suppressed. As a result, the fuel can be burned more reliably.

  Moreover, since the current transformation part 35 is formed in the piston 4, the fuel injected with the injector 34 can be collected in the subcombustion chamber 31 in which the electric field was created. For this reason, most of the fuel injected by the injector 34 is located in the auxiliary combustion chamber 31. Therefore, when the fuel is ignited by the spark plug 15, the flame propagation speed of most of the fuel can be improved. The combustion can be promoted. Thereby, misfire immediately after ignition of fuel can be suppressed more reliably, and flame propagation failure can be suppressed more reliably. As a result, the fuel can be burned more reliably.

  Further, the high voltage power supply unit 20 applies potentials having different polarities to the two conductive units 33 within a range of ± 10 ° in the crank angle when the crankshaft rotates with reference to the position of the top dead center of the piston 4 in the compression stroke. By continuing, a potential difference is continuously generated between the two auxiliary combustion chamber walls 32, so that an electric field is generated in the auxiliary combustion chamber 31 in this range. In addition, most of the fuel is collected in the auxiliary combustion chamber 31. When this fuel is ignited, combustion is accelerated by corona discharge generated in the auxiliary combustion chamber 31, so Fuel burns in a short time. For these reasons, even when the electric field created in the auxiliary combustion chamber 31 is in the above range, the flame propagation speed of most of the fuel can be improved. Furthermore, since the timing for generating a potential difference in the conductive portion 33 connected to the sub-combustion chamber 31 is limited, the energy for creating the electric field can be minimized. As a result, it is possible to more reliably improve the lean limit while suppressing energy consumption.

  This internal combustion engine has substantially the same configuration as the internal combustion engine according to the first embodiment, but is characterized in that a conductive portion is connected in the vicinity of the outer peripheral portion of the combustion chamber. Since other configurations are the same as those of the first embodiment, the description thereof is omitted and the same reference numerals are given. FIG. 3 is a schematic diagram showing the configuration of the internal combustion engine according to the third embodiment of the present invention. In the internal combustion engine 50 shown in the figure, the high-voltage power supply unit 20 is connected to the connecting rod 5 and the conductive portion 53, and the conductive portion 53 is provided in the cylinder head 3. The conductive portion 53 is connected to a combustion chamber forming portion 51 that is a portion of the cylinder head 3 that forms the combustion chamber 10. Furthermore, the position is located in the vicinity of the outer peripheral portion 52 that is the portion of the combustion chamber forming portion 51 that is positioned closest to the cylinder block 2 or the outer portion of the combustion chamber forming portion 51 in the radial direction of the piston 4. It is connected.

  In addition, a piston ring 55 is disposed on a piston side surface 54 that is a side surface of the piston 4 and that is a portion facing the cylinder block 2 in the piston 4. The piston ring 55 is provided to be engaged with a narrow groove formed on the piston side surface 54 over the entire circumference, and protrudes from the piston side surface 54 in the direction of the cylinder block 2 so that the piston side surface 54 substantially extends around the piston side 54. It is arranged across. The piston ring 55 formed in this way is closer to the cylinder block 2 than the piston side surface 54, and a plurality of piston rings 55 are arranged side by side on the piston side surface 54.

  As described above, among the plurality of piston rings 55 provided on the piston side surface 54, the space formed by the piston ring 55 located closest to the combustion chamber 10, the piston side surface 54, and the cylinder block 2 is a clevis volume 56. Is formed. The clevis volume 56 is located near the outer peripheral portion 52 of the combustion chamber forming portion 51 of the cylinder head 3 when the piston 4 is located near the top dead center. For this reason, when the piston 4 is positioned near the top dead center, the clevis volume 56 is positioned near the portion of the combustion chamber forming portion 51 to which the conductive portion 53 is connected.

  The internal combustion engine 50 according to the third embodiment is configured as described above, and the operation thereof will be described below. A conductive portion 53 provided in the internal combustion engine 50 is provided in the cylinder head 3 and connected to the combustion chamber forming portion 51. Further, the connected position is in the vicinity of the outer peripheral portion 52 of the combustion chamber forming portion 51. In addition, the conductive portion 53 is connected to the high-voltage power supply unit 20 similarly to the conductive portion 21 included in the internal combustion engine 1 of the first embodiment. The high-voltage power supply unit 20 is further connected to the piston 4 by the connecting pin 6. The connecting rod 5 is connected. For this reason, when potentials having different polarities are applied to the conductive portion 53 and the connecting rod 5 by the high-voltage power supply portion 20, a potential difference is generated between the outer peripheral portion 52 of the combustion chamber forming portion 51 and the piston 4, and between them. An electric field is created.

  The high-voltage power supply unit 20 has a polarity with respect to the conductive portion 53 and the connecting rod 5 in the range of 0 ° to + 20 ° in the crank angle when the crankshaft rotates with reference to the position of the top dead center of the piston 4 in the compression stroke. By continuously applying different potentials, a potential difference is continuously generated between the outer peripheral portion 52 of the combustion chamber forming portion 51 and the piston 4. For this reason, the electric field between the outer peripheral portion 52 of the combustion chamber forming portion 51 and the piston 4 is created in the range of 0 ° to + 20 ° in the crank angle when the crankshaft rotates.

  On the other hand, since the piston 4 is provided with a piston ring 55, a clevis volume 56 is formed between the piston ring 55, the piston side surface 54, and the cylinder block 2. When the crank angle is in the range of 0 ° to + 20 ° during rotation, the clevis volume 56 is positioned in the vicinity of the outer peripheral portion 52 of the combustion chamber forming portion 51. For this reason, an electric field created by the high voltage power supply unit 20 creating a potential difference between the outer peripheral portion 52 of the combustion chamber forming unit 51 and the piston 4 is created in the clevis volume 56.

  Further, the range of 0 ° to + 20 ° in the crank angle at the time of rotation of the crankshaft with reference to the position of the top dead center of the piston 4 in the compression stroke is a range in which the fuel in the combustion chamber 10 burns. By creating an electric field, corona discharge can be generated in the clevis volume 56 when the fuel located in the clevis volume 56 burns. For this reason, the flame propagation speed in the clevis volume 56 is improved.

  In the internal combustion engine 50 described above, the conductive portion 53 is provided in the cylinder head 3. Since the cylinder head 3 is not a portion that operates even when the internal combustion engine 50 is in operation, the conductive portion 53 can be easily provided. Further, since the conductive portion 53 is connected to the combustion chamber forming portion 51 that forms the combustion chamber 10, the conductive portion 53 is connected to the connecting rod 5 via the connection pin 6 and the combustion chamber forming portion 51 to which the conductive portion 53 is connected. An electric field can be generated in most of the combustion chamber 10 by generating a potential difference between the piston 4 and the connected piston 4 by the high-voltage power supply unit 20. Thereby, since the flame at the time of fuel combustion propagates more reliably in the electric field, the flame propagation speed of the fuel in the combustion chamber 10 can be improved more reliably. As a result, the lean limit can be easily and more reliably improved.

  Further, since the fuel located in the clevis volume 56 is likely to come into contact with the piston side surface 54, the piston ring 55, and the cylinder block 2, the temperature at the time of combustion of the fuel tends to decrease. When the temperature during combustion of the fuel decreases, the combustion state deteriorates and HC (hydrocarbon), which is a substance that may affect air pollution, is likely to be generated, but an electric field is created in the clevis volume 56 to corona discharge. By generating this, the flame propagation speed of this part can be improved. Thereby, combustion of the fuel located in the clevis volume 56 can be promoted, and the portion where the combustion state is bad can be reduced. As a result, the lean limit can be improved more reliably.

  The high-voltage power supply unit 20 has a polarity with respect to the conductive portion 53 and the connecting rod 5 in the range of 0 ° to + 20 ° in the crank angle when the crankshaft rotates with reference to the position of the top dead center of the piston 4 in the compression stroke. The electric field can be created in the clevis volume 56 within this range by continuously applying the different potentials and continuously generating a potential difference between the outer peripheral portion 52 of the combustion chamber forming portion 51 and the piston 4. Since the clevis volume 56 is formed at a position away from the spark plug 15, the fuel flame ignited by the spark plug 15 in the clevis volume 56 is propagated into the clevis volume 56 after a predetermined time has elapsed. . For this reason, an electric field can be created in the clevis volume 56 in the latter half of the combustion of the fuel by setting the range in which the potential difference is continuously generated between the outer peripheral portion 52 of the combustion chamber forming portion 51 and the piston 4 as described above. The corona discharge can be generated when the fuel in the clevis volume 56 burned in the latter half of the combustion burns. For this reason, combustion can be promoted when the fuel in the clevis volume 56 burns. In addition, since the time for creating the electric field in the clevis volume 56 is limited, the energy for creating the electric field can be minimized. As a result, it is possible to more reliably improve the lean limit while suppressing energy consumption.

  In the first and third embodiments, the high-voltage power supply unit 20 is connected to the connecting rod 5 and applies a potential to the piston 4 through the connecting pin 6, but the high-voltage power supply unit 20 is not connected to the connecting rod 5. It may be connected to the part. The position to which the high-voltage power supply unit 20 is connected is not limited as long as it can reliably apply a potential to the piston 4 when the internal combustion engines 1 and 50 are operated.

  In addition, in the first embodiment, the electric field is generated in the combustion chamber 10 within a range of ± 60 ° in the crank angle when the crankshaft rotates with reference to the position of the top dead center of the piston 4 in the compression stroke. In Example 2, ± 10 ° with reference to the same position, and in Example 3, the range is 0 ° to + 20 ° with reference to the same position. Other than that. For example, in the internal combustion engine according to the second embodiment, when the electric field is generated in the combustion chamber 10, the electric field is continuously generated in the range of 0 ° to 20 ° with respect to the above position as in the third embodiment. Since combustion can be promoted in the latter half of combustion, the combustion state can be improved, and HC emissions in the second half of combustion can be reduced.

  In addition, when the electric field is generated in the auxiliary combustion chamber 31 in the internal combustion engine 30 according to the second embodiment within the range of ± 30 ° with respect to the above position, the corona is more reliably generated during the combustion of the fuel. A discharge can be generated. As a result, the flame propagation speed can be improved more reliably and the lean limit can be improved, so that the lean operation can be performed, and the fuel consumption can be improved and NOx can be reduced. In addition, since an electric field has already been generated at the time of ignition by the spark plug 15, misfire immediately after ignition of fuel can be suppressed. Furthermore, the generation of HC that is likely to be generated in the latter half of combustion can be suppressed, and the release of HC into the atmosphere can be reduced.

  FIG. 4 is a diagram illustrating a modification of the third embodiment. In the third embodiment, the spark plug 15 is provided between the intake valve 11 and the exhaust valve 12 in the same manner as the spark plug 15 provided in the internal combustion engine 1 according to the first embodiment. You may provide in a part other than that. For example, as shown in FIG. 4, the spark plug 15 may be provided closer to the outer peripheral portion 52 of the combustion chamber forming portion 51 than the intake valve 11 and the exhaust valve 12. That is, the spark plug 15 may be provided in the vicinity of the conductive portion 53. Thus, by positioning the spark plug 15 in the vicinity of the portion where the conductive portion 53 is provided, the flame immediately after ignition when the fuel is ignited by the spark plug 15 can be positioned in the electric field. Thereby, the flame propagation speed immediately after ignition can be improved and combustion can be facilitated, so that misfire immediately after ignition can be suppressed. As a result, the fuel can be burned more reliably.

  Furthermore, since the ignition part 16 can be brought close to the clevis volume 56 by arranging the spark plug 15 at the above position, the fuel in the clevis volume 56 is easily ignited. Thereby, the combustion of the fuel in the clevis volume 56 can be more reliably promoted and the fuel in this portion can be easily burned, so that the portion having a bad combustion state can be reduced. As a result, HC emissions can be reduced, and the lean limit can be improved more reliably. Further, fuel efficiency can be improved by improving the lean limit.

  When the ignition plug 15 is positioned in the vicinity of the conductive portion 53 in this way, the high voltage power source portion 20 uses the crank angle when the crankshaft rotates with reference to the position of the top dead center of the piston 4 in the compression stroke. It is preferable that a potential difference is continuously generated between the outer peripheral portion 52 of the combustion chamber forming portion 51 and the piston 4 in the range of −30 ° to + 30 ° in order to create an electric field in the combustion chamber 10. When the spark plug 15 is positioned in the vicinity of the conductive portion 53, the flame ignited by the spark plug 15 is propagated to the electric field immediately after ignition. Corona discharge can be reliably generated during fuel combustion. Thereby, a flame propagation speed can be improved more reliably and combustion of fuel can be promoted. As a result, the lean limit can be improved more reliably.

  Further, in each of the above-described embodiments, corona discharge occurs when a flame due to the combustion of fuel propagates in the electric field, but the corona discharge is a high voltage power source even in a state where no flame propagates in the electric field. It may be generated by causing a potential difference in each part facing the combustion chamber 10 by the part 20.

  As described above, the internal combustion engine according to the present invention is useful for an internal combustion engine that performs lean combustion, and is particularly suitable for improving the lean limit.

1 is a schematic diagram illustrating a configuration of an internal combustion engine according to Embodiment 1 of the present invention. It is the schematic which shows the structure of the internal combustion engine which concerns on Example 2 of this invention. It is the schematic which shows the structure of the internal combustion engine which concerns on Example 3 of this invention. FIG. 10 is a diagram showing a modification of the third embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Cylinder block 3 Cylinder head 4 Piston 5 Connecting rod 6 Connecting pin 7 Gasket 10 Combustion chamber 11 Intake valve 12 Exhaust valve 13 Valve stem 14 Valve surface 15 Spark plug 16 Ignition part 20 High voltage power supply part 21 Conductive part 30 Internal combustion engine 31 Subcombustion Chamber 32 Subcombustion Chamber Wall 33 Conductive Part 34 Injector 35 Current Transformer 50 Internal Combustion Engine 51 Combustion Chamber Forming Part 52 Outer Peripheral Part 53 Conductive Part 54 Piston Side 55 Piston Ring 56 Clevis Volume

Claims (7)

In an internal combustion engine that burns fuel by igniting fuel in a combustion chamber with a spark plug,
An electric field generating means for generating an electric field at a position where a flame caused by the combustion of the fuel propagates when the fuel burns in the combustion chamber and generating a corona discharge at least when the flame propagates in the electric field is provided. An internal combustion engine characterized by the above. The combustion chamber is constituted by a cylinder head provided with intake and exhaust valves,
A piston faces the combustion chamber,
2. The electric field generating means is connected to the intake / exhaust valve and the piston, and creates the electric field by generating a potential difference between the intake / exhaust valve and the piston. Internal combustion engine. The combustion chamber has a sub-combustion chamber that is formed in an electrically separate two-divided structure and provided with the spark plug,
2. The internal combustion engine according to claim 1, wherein the electric field generating means is connected to the sub-combustion chamber, and creates an electric field in the sub-combustion chamber by generating a potential difference between the parts having the two-part structure. organ. Fuel is directly injected into the combustion chamber by fuel injection means,
The internal combustion engine according to claim 3, wherein the fuel injected by the fuel injection means is collected in the auxiliary combustion chamber. The combustion chamber is constituted by a cylinder head,
A piston faces the combustion chamber,
2. The internal combustion engine according to claim 1, wherein the electric field generating unit is connected to the cylinder head and the piston and generates the electric field by generating a potential difference between the cylinder head and the piston. organ.   The electric field generating means generates the electric field by generating a potential difference between a vicinity of an outer peripheral portion of a combustion chamber forming portion which is a portion forming the combustion chamber of the cylinder head and the piston. Item 6. The internal combustion engine according to Item 5.   The internal combustion engine according to claim 6, wherein the spark plug is positioned in the vicinity of a portion of the cylinder head where the electric field generating means is provided.

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