JP2006177254A - Combustion chamber structure for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a combustion chamber structure for an internal combustion engine increasing combustion speed and demonstrating knocking suppression effect. <P>SOLUTION: Space parts 21, 22 provided in a squish area 12 around the combustion chamber 10 of the internal combustion engine, spark plugs 16, 17 arranged in the space areas, and passages 23, 24 establishing communication between the space parts and the combustion chamber are provided. The two spark plugs are provided in a symmetrical position in plane view of the combustion chamber, and a spark plug 15 is provided at a roughly center part of the combustion chamber. The spark plugs 16, 17 arranged in the space parts in the squish area are ignited at delayed timing as compared with the ignition plug 15 provided at the roughly center part. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a combustion chamber structure for an internal combustion engine, and more particularly to a combustion chamber structure for an internal combustion engine that improves combustion speed and has a large knocking suppression effect.

  Combustion of the air-fuel mixture ignited in the central part of the combustion chamber propagates to the outer edge of the combustion chamber. However, if the flame propagation speed is insufficient, the air-fuel mixture at the outer edge that is at a high pressure is Ignites and knocks. In order to suppress the occurrence of knocking, it is necessary to retard the ignition timing and the compression ratio, and the efficiency deteriorates. That is, because of the occurrence of knocking, the ignition timing cannot be advanced or the compression ratio cannot be increased, so that the performance deteriorates.

  In the three-point ignition method, one point is provided with a spark plug in the center of the combustion chamber, two points are provided with a spark plug in the squish region, An annular space (opened by 360 °) is formed around the arranged spark plug.

  Japanese Patent Application Laid-Open No. 7-26961 (Patent Document 1) includes one spark plug at the center and two spark plugs at the outer periphery, and by injecting a flame along the outer periphery using the ignition plug at the outer periphery as a torch. A technique for forming an annular flame at an early stage of combustion is disclosed. In Patent Document 2, the spark plug at the outer peripheral portion is not provided in the squish region.

Japan Society of Invention Disclosure Technique No. 2003-502933 JP 7-26961 A

It is desired that the combustion rate is improved and the effect of suppressing knocking is great.
It is desired to achieve both of multipoint ignition and turbulence enhancement by squish.

  An object of the present invention is to provide a combustion chamber structure of an internal combustion engine that improves combustion speed and has a large knocking suppression effect.

  A combustion chamber structure of an internal combustion engine according to the present invention includes a space provided in a squish area around the combustion chamber of the internal combustion engine, a spark plug disposed in the space, and the space and the combustion chamber. It is characterized by having a passage to be made.

  In the combustion chamber structure of the internal combustion engine according to the present invention, two ignition plugs are provided at target positions in plan view of the combustion chamber, and further includes an ignition plug provided at a substantially central portion of the combustion chamber. It is characterized by that.

  In the combustion chamber structure of the internal combustion engine of the present invention, the passage is provided along the circumferential direction of the combustion chamber.

  In the combustion chamber structure of the internal combustion engine according to the present invention, the spark plug disposed in the space portion of the squish area is ignited at a delayed timing as compared with the spark plug provided in the substantially central portion. It is said.

  In the combustion chamber structure of the internal combustion engine of the present invention, the internal combustion engine is an in-cylinder direct injection engine having a stratified operation mode. In the stratified operation mode, only the ignition plug provided at the substantially central portion is ignited. It is characterized by that.

  In the combustion chamber structure of the internal combustion engine of the present invention, the internal combustion engine is an in-cylinder direct injection engine having a stratified operation mode, and a spark plug provided in the substantially central portion on the top surface of the piston, and the squish area Cavities into which combustion is injected in the stratified operation mode are formed at positions corresponding to the spark plugs disposed in the space, and the passage is directed to the spark plug provided in the substantially central portion. It is characterized by being provided as follows.

  According to the combustion chamber structure of the internal combustion engine of the present invention, the combustion speed can be improved and the effect of suppressing knocking is great.

  Hereinafter, an embodiment of a combustion chamber structure of an internal combustion engine of the present invention will be described in detail with reference to the drawings.

(First embodiment)
The first embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a view of the combustion chamber as seen from the lower surface side. 2 is a cross-sectional view taken along the line AA in FIG. In FIG. 1, reference numeral 10 is a combustion chamber, 11 is a cylinder bore, 12 is a squish area, 13 is an exhaust valve, 14 is an intake valve, and 15 to 17 are first to third spark plugs. In FIG. 2, reference numeral 100 denotes a piston, 100a denotes a piston top surface, and 200 denotes a cylinder head.

  In this embodiment, three spark plugs are provided (reference numerals 15 to 17). One point of the first spark plug 15 is provided substantially in the center, and the remaining two points of the second and third spark plugs 16 and 17 are located between the exhaust valve 13 and the intake valve 14 at the outer edge of the combustion chamber 10. Is provided. As indicated by reference numeral 12, a squish region is provided around the combustion chamber 10.

  As shown in FIGS. 1 and 2, spaces 21 and 22 are provided around the second and third spark plugs 16 and 17. Tubular regions 23 and 24 connecting the spaces 21 and 22 and the combustion chamber 10 are provided. FIG. 2 shows a state in which the piston 100 is in the vicinity of the top dead center. At this time, the tubular region 23, between the top surface 100 a of the piston 100 and the recesses 201 and 202 formed in the cylinder head 200 is shown. 24, spaces 21 and 22 are formed. As shown in FIG. 1, the tubular regions 23, 24 are inclined so as to have a predetermined angle from the imaginary line segment (center line) L in the radial direction of the cylinder bore 11 along the circumferential direction of the combustion chamber 10. Installed.

  According to the first embodiment, when ignition is performed, normal flame propagation spreads from the first spark plug 15 and from the second and third spark plugs 16 and 17, the spaces 21 and 22 around the plug are initially set. The pressure of the gas increases, and high-temperature gas that has been burned or is burning is blown into the combustion chamber 10 through the tubular regions 23 and 24.

  The gas blown into the combustion chamber 10 through the tubular regions 23 and 24 burns the air-fuel mixture in the outer peripheral portion away from the first spark plug 15 and at the same time creates a swirling flow in the circumferential direction, thereby combusting. Increase speed. As a result, knocking is suppressed, and the ignition timing can be advanced and the compression ratio can be increased, thereby improving the performance.

(Second Embodiment)
Next, a second embodiment will be described.
In the second embodiment, description of portions common to the first embodiment is omitted (the same applies to the following embodiments).

  In the configuration of the first embodiment, if ignition is performed simultaneously in the first, second, and third spark plugs 15 to 17, knocking is suppressed as described above, so that the ignition timing can be advanced. Become. However, when the ignition timing is advanced, ignition is performed when the piston is in a relatively lower position, so that a gap is increased in the squish area 12, and the ejection from the tubular areas 23 and 24 is weakened. As a result, the effect of suppressing knocking is weakened, and for this reason, the ignition timing may not be sufficiently advanced.

  Therefore, in the second embodiment, the ignition of the first spark plug 15 is performed at the timing of MBT, and the ignition timing of the second and third spark plugs 16 and 17 is delayed so that the squish region 12 becomes sufficiently narrow. Ignition is performed near TDC.

  As described above, by shifting the ignition timing, flame propagation is started at an efficient timing by the first spark plug 15 while maintaining the knocking suppression effect by the second and third spark plugs 16 and 17.

(Third embodiment)
Next, a third embodiment will be described.

When the configuration of the first embodiment is applied to an in-cylinder direct injection engine having a stratified operation mode, the first spark plug 15 is capable of igniting an air-fuel mixture (stratified air-fuel mixture) in a piston cavity substantially at the center of the piston. Only the ignition of the second and third spark plugs 16 and 17 is wasted.

  Therefore, in the third embodiment, when the configuration of the first embodiment is applied to an in-cylinder direct injection engine having a stratified operation mode, whether or not the ignition plugs 15 to 17 are ignited in the homogeneous operation mode and the stratified operation mode is determined. change. That is, in the homogeneous operation mode, ignition is performed by the first, second, and third spark plugs 15 to 17, and in the stratified operation mode, ignition is performed only by the first spark plug 15.

  As described above, by stopping the meaningless ignition during the stratified operation, the ignition energy can be reduced, which leads to an improvement in fuel consumption.

(Fourth embodiment)
Next, a fourth embodiment will be described with reference to FIGS. 3 and 4.

  FIG. 3 is a view of the combustion chamber as seen from the lower surface side. FIG. 4 is a view of the piston as viewed from above. In the fourth embodiment, as in the third embodiment, the configuration of the first embodiment is applied to an in-cylinder direct injection engine having a stratified operation mode. However, as shown in FIG. 3, in the third embodiment, unlike the tubular regions 23 and 24 in FIG. 1, the tubular regions 25 and 26 are provided to face the first spark plug 15.

  As shown in FIG. 4, first to third cavities 31 to 33 are provided on the top surface of the piston 30 at positions corresponding to the first to third spark plugs 15 to 17, respectively. The first cavity 31 provided so as to correspond to the first spark plug 15 is for normal stratified combustion, and the second and second cavities provided so as to correspond to the second and third spark plugs 16 and 17, respectively. The three cavities 32 and 33 are for ejecting combustion gas from the tubular regions 25 and 26. Reference numeral 28 denotes an injector, and reference numeral 34 denotes a valve recess.

  The injector 28 has three or more holes, and injects fuel 41 for stratified combustion toward the first cavity 31, and fuels 42 and 43 for ejecting combustion gas from the tubular regions 25 and 26. Injected toward the second and third cavities 32 and 33.

  According to the fourth embodiment, the fuels 42 and 43 supplied to the second and third cavities 32 and 33 are combusted by the ignition of the second and third spark plugs 16 and 17, and are combusted from the tubular regions 25 and 26. Gas spouts out. Thereby, combustion of the air-fuel mixture in the first cavity 31 is accelerated, and fuel efficiency is improved by increasing efficiency.

(Fifth embodiment)
The fifth embodiment will be described with reference to FIGS.

  As means for improving the combustion speed, there are shortening of the flame propagation distance by multipoint ignition and turbulence strengthening by squish, but it is very difficult to realize both at the same time. When trying to obtain a strong squish, as shown in FIG. 9, it is necessary to make the outer periphery of the bore shown by hatching the squish area 51. Space is lost only in the center.

  5 is a view of the combustion chamber of the fifth embodiment viewed from the lower surface side, FIG. 6 is a cross-sectional view taken along line AA in FIG. 5, and FIG. 7 is a cross-sectional view taken along line BB in FIG. FIG. 8 is an enlarged view of a main part of the fifth embodiment.

  As shown in FIGS. 5 to 8, as a method of arranging a plurality of spark plugs without reducing the squish area 52, a cavity 53 is provided in the cylinder head 60 above the squish area 52, and the spark plug is placed in the cavity 53. 54 is accommodated. The cavity 53 is partitioned by a wall portion 55, and an opening 56 is formed in a part of the wall portion 55. The communication between the cavity 53 and the combustion chamber 10 is performed through an opening 56 provided in a wall portion connected from the squish portion 52 to the ceiling surface 10 a of the combustion chamber 10. In FIG. 6, arrow Y1 has shown the flame ejection direction, and the code | symbol 61 has shown the top surface of the piston in FIG.6 and FIG.8.

  As shown in FIG. 8, the cavity 53 is provided as a space surrounded by the wall portion 55 in the cylinder head 60, and the spark plug 54 is accommodated in the space. An opening 56 is formed in a surface of the wall 55 that faces the center of the combustion chamber 10 (see FIG. 5). Since the opening 56 is formed only on the surface facing the central portion of the combustion chamber 10, when ignition is performed by the spark plug 54 in the cavity 53, the flame is ejected vigorously from the opening 56.

  A cavity 53 having an opening 56 toward the center of the combustion chamber 10 is provided in the squish area 52 of the combustion chamber 10 of the cylinder head 60. By igniting the cavity 53, the flame ejected from the cavity 53 and the squish flow are integrated. Thus, a very strong turbulence is generated, and the combustion speed is improved.

  As shown in FIGS. 6, 8, and 2, in the third embodiment (FIGS. 6 and 8), the cavity 53 that accommodates the spark plug 54 is only by the wall portion 55, in other words, only by the cylinder head 60 side. Is formed. In contrast, in the first embodiment (FIG. 2), spaces 21 and 22 and tubular regions 23 and 24 are formed by the top surface 100a of the piston 100 and the recesses 201 and 202 of the cylinder head 200.

  From this, when soot (deposit) is accumulated in the spaces 21 and 22 or the cavity 53, the configuration of the first embodiment is such that the lower side of the spaces 21 and 22 is opened (the piston 100 is located at the lower position). The advantage is that it is easy to remove soot. On the other hand, as shown in FIGS. 6 and 8, in the third embodiment, as the piston rises, a compression space is generated between the top surface 61 of the piston and the lower surface of the wall portion 55 to generate a squish flow. There is an advantage.

  Further, in the third embodiment, the lower surface of the cavity 53 is configured by the wall portion 55 (the top surface 61 of the piston is not a component of the cavity 53), and therefore, at any timing regardless of the position of the piston. A flame can be ejected from the opening 56.

  As described above, according to the fifth embodiment, both the multipoint ignition 54, 54 and the large squish area 52 can be achieved. In addition, a torch-like flame ejection is generated from the cavity 53 in which the spark plug 54 is accommodated, and the direction thereof coincides with the direction of the squish flow, so that a stronger turbulence addition effect is exhibited.

  Since the flow velocity of the flame ejected from the cavity 53 is very high, an increase in cooling loss at the opening 56 and wear of the opening 56 are likely to occur. In order to prevent this, a ceramic insert is inserted into the portion (cavity 53) where the tip of the spark plug 54 is accommodated, as in the sub-chamber diesel engine. That is, the wall portion 55 forming the cavity 53 is made of a ceramic having low thermal conductivity, thereby suppressing an increase in cooling loss and wear of the opening 56 when the flame is ejected.

It is the figure which looked at the combustion chamber of 1st Embodiment of the combustion chamber structure of the internal combustion engine of this invention from the lower surface side. FIG. 2 is a cross-sectional view taken along the line AA of FIG. It is the figure which looked at the combustion chamber of 4th Embodiment of the combustion chamber structure of the internal combustion engine of this invention from the lower surface side. It is the figure which looked at the piston of 4th Embodiment of the combustion chamber structure of the internal combustion engine of this invention from the upper surface side. It is the figure which looked at the combustion chamber of 5th Embodiment of the combustion chamber structure of the internal combustion engine of this invention from the lower surface side. It is the sectional view on the AA line of FIG. FIG. 6 is a sectional view taken along line B-B in FIG. 5. It is an enlarged view of the principal part of 5th Embodiment of the combustion chamber structure of the internal combustion engine of this invention. It is a figure which shows the squish area of the combustion chamber structure of a general internal combustion engine.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Combustion chamber 11 Cylinder bore 12 Squish area | region 13 Exhaust valve 14 Intake valve 15 1st spark plug 16 2nd spark plug 17 3rd spark plug 21 Space 22 Space 23 Tubular area 24 Tubular area 28 Injector 30 Piston 31 1st cavity 32 2nd Cavity 33 Third cavity 34 Valve recess 41 Fuel for stratified combustion 42, 43 Fuel for ejection of combustion gas 51 Squish area 52 Squish area 53 Cavity 54 Spark plug 55 Wall portion 56 Opening portion 60 Cylinder head 61 Piston top surface 100 Piston 100a Piston top surface 200 Cylinder head 201 Recessed portion 202 Recessed portion L Virtual line segment Y1 Flame ejection direction

Claims (6)

A space provided in a squish area around the combustion chamber of the internal combustion engine;
A spark plug disposed in the space;
A combustion chamber structure for an internal combustion engine, comprising: a passage for communicating the space and the combustion chamber. The combustion chamber structure of the internal combustion engine according to claim 1,
Two spark plugs are provided at target positions in plan view of the combustion chamber,
Furthermore,
A combustion chamber structure for an internal combustion engine, comprising an ignition plug provided at a substantially central portion of the combustion chamber. In the combustion chamber structure of the internal combustion engine according to claim 1 or 2,
The combustion chamber structure for an internal combustion engine, wherein the passage is provided along a circumferential direction of the combustion chamber. In the combustion chamber structure of the internal combustion engine according to claim 2,
A combustion chamber structure of an internal combustion engine, wherein the ignition plug disposed in the space portion of the squish area is ignited at a delayed timing as compared with the ignition plug provided in the substantially central portion. The combustion chamber structure of the internal combustion engine according to claim 2 or 4,
The internal combustion engine is an in-cylinder direct injection engine having a stratified operation mode,
In the stratified operation mode, only the ignition plug provided at the substantially central portion is ignited. The combustion chamber structure of the internal combustion engine according to claim 2 or 4,
The internal combustion engine is an in-cylinder direct injection engine having a stratified operation mode,
Combustion is injected in the stratified operation mode at positions corresponding to the spark plug provided in the substantially central portion and the spark plug disposed in the space portion of the squish area on the top surface of the piston. A cavity is formed,
The combustion chamber structure of an internal combustion engine, wherein the passage is provided so as to face the spark plug provided in the substantially central portion.

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