KR20050014616A - Swirl chamber used in association with a combustion chamber for diesel engines - Google Patents

Abstract

PURPOSE: A swirl combustion chamber of a diesel engine is provided to decrease both nitrogen oxide and smoke by mixing the air and fuel by generating effective vortex and dispersing the fuel in the chamber. CONSTITUTION: A swirl combustion chamber defined by a piston, a cylinder, and a cylinder head comprises a mouthpiece(7) installed in a hole of the cylinder head having a bottom opening groove and composed of an upper opening groove(7a), wherein the bottom and upper opening grooves form one space intended for a vortex chamber(8); a main nozzle hole(11) formed through a base wall(10) of the mouthpiece to facilitate communication between the combustion chamber and the vortex chamber; and a pair of auxiliary nozzle holes(12) formed through the base wall of the mouthpiece and arranged in the opposite side of a center shaft of the main nozzle hole with symmetrical to each other. Each auxiliary nozzle hole passes through the inside of a first circular body(15) occupying 70% radius of an imaginary second circular body formed around the center of the upper opening groove.

Description

SWIRL CHAMBER USED IN ASSOCIATION WITH A COMBUSTION CHAMBER FOR DIESEL ENGINES}

The present invention relates to a combustion chamber for a diesel engine, and more particularly to an improved vortex chamber used in combination with a combustion chamber for a diesel engine.

In general, diesel engines are known as a major source of environmental pollutants such as NOx and soot. However, no effective measures have been taken to solve such problems. These problems are known to be due to incomplete combustion in the engine due to improper mixing of air and fuel. In order to solve this problem, a vortex combustion system is generally used. One example of dealing with this problem is disclosed in Japanese Patent Application Laid-Open No. 07-97924. Hereinafter, referring to FIG. 10, a known combustion chamber in which a vortex chamber is installed will be described.

10 (A) and 10 (B), for convenience only, the right side (center axis 103 side) is "rearward" and the left side (cylinder liner 104 side) is "forward". do. In the known combustion chamber shown in Fig. 10A, a cylinder 101 having a cylinder head 105, a reciprocating piston 102, and a combustion chamber 109 are provided. Furthermore, the cylinder head 105 is provided with a groove 106 in which a mouthpiece 107 is installed. The mouthpiece 107 is provided with an upper opening groove 107a and the groove 106 includes a bottom opening groove 106a. The upper open groove 107a and the bottom open groove 106a constitute a space 108 that functions as a vortex chamber, hereinafter referred to as the “swirl chamber 108”. The vortex chamber 108 is in communication with the combustion chamber 109 through a main nozzle hole 111 having a central axis 113. The main nozzle hole 111 is inclined forward toward the vortex chamber 108. The mouthpiece 107 is additionally provided with a pair of auxiliary nozzle holes 112 through which auxiliary air is forced into the vortex chamber 108 in the compression stroke. As shown in Fig. 10A, the auxiliary nozzle holes 112 are symmetrically disposed on opposite sides about the central axes 113-114.

However, under the above-described configuration, the main disadvantage is that the auxiliary air injected through the auxiliary nozzle hole 112 does not reach the central portion of the vortex chamber 108, so that an effective vortex cannot be generated therein. In this way, the auxiliary air hole 112 cannot be used completely with the auxiliary air.

The above disadvantage is due to the arrangement of the auxiliary nozzle holes 112 as follows.

The radius of the open end 107b and the radius of the circular body 115 are regarded as the center of the virtual circular body (actually, the sphere) 115 as the center of the open end 107b of the upper open groove 107a. Is set to 100% and 70%, respectively.

10 (A) and 10 (B), the circular body 115 having a radius of 70% passes outward, while the circular body 115 having a radius of 50% passes inward. In this situation, the central axes 112a-112b of each of the auxiliary nozzle holes 112 pass outside the circular body 115.

In another aspect, the auxiliary nozzle hole 112 has a center 112c away from the center of the vortex chamber 108 such that the central axes 112a-112b of the auxiliary nozzle hole 112 are inside the 50% circular body 115. Can not pass through.

It is an object of the present invention to provide an improved vortex chamber which is capable of generating an effective vortex so that air and fuel are well mixed and the fuel is well dispersed within the vortex chamber.

It is another object of the present invention to provide an improved vortex chamber which can reduce both the generation of NOx and soot in a conventional system.

FIG. 1 is a diagram illustrating a first embodiment of the present invention, in which FIG. 1A is a plan view, FIG. 1B is a sectional view taken along the line BB of FIG. 1A, and FIG. ) Is a bottom view, and FIG. 1D is a cross-sectional view taken along the line DD.

FIG. 2 is a view illustrating the nozzle hole of the mouthpiece shown in FIG. 1, FIG. 2A is a longitudinal side view of the mouthpiece, FIG. 2B is a perspective view of the nozzle hole, and FIG. (C) is a figure of the nozzle hole seen from the direction shown by arrow C in FIG. 2 (A), and FIG. 2 (D) is a bottom view of the nozzle hole.

3 is a diagram illustrating the vortex chamber shown in FIG. 1, FIG. 3A is a cross-sectional plan view of a cylinder with a piston, and FIG. 3B is a side cross-sectional view of the vortex chamber and its peripheral components.

FIG. 4 is a graph showing the NOx content in the exhaust gas in comparison with the first comparative example without any auxiliary nozzle hole under the first embodiment shown in FIG. 3.

FIG. 5 is a graph showing the amounts of NOx and fumes discharged under the first embodiment shown in FIG. 3 in comparison with the first and second comparative examples.

Fig. 6 is a graph showing the relationship between the cross-sectional area of the auxiliary nozzle hole and the characteristics of the gas discharged from the vortex chamber of Fig. 3, and Fig. 6 (A) shows the variation of the NOx amount with respect to the cross-sectional area, and Fig. 6 (B). Denotes a variation in the amount of soot with respect to the cross-sectional area, and FIG.

Fig. 7 is a view illustrating the mouthpiece of the second embodiment, Fig. 7A is a plan view, Fig. 7B is a sectional view taken along the line BB in Fig. 7A, and Fig. 7C. 7 is a bottom view, and FIG. 7D is a sectional view taken along the line DD in FIG. 7B.

Fig. 8 is a view illustrating the mouthpiece of the third embodiment, in which Fig. 8A is a plan view, Fig. 8B is a sectional view taken along the line BB in Fig. 8A, and Fig. 8C. Is a bottom view, and FIG. 8 (D) is a cross-sectional view taken along the line DD in FIG. 8 (B).

Fig. 9 is a view illustrating the mouthpiece of the fourth embodiment, in which Fig. 9A is a plan view, Fig. 9B is a sectional view taken along the line BB in Fig. 9A, and Fig. 9C. Is a bottom view, and FIG. 9 (D) is a sectional view taken along the line DD in FIG. 9 (B).

10 is a diagram illustrating a known vortex chamber, in which FIG. 10 (A) is a plan view of the mouthpiece and piston, and FIG. 10 (B) is a longitudinal side view of the vortex chamber and its peripheral components.

According to the present invention, in a vortex chamber type combustion chamber of a diesel engine, the combustion chamber is defined by a piston, a cylinder, and a cylinder head;

A mouthpiece installed in a hole of a cylinder head having a bottom opening groove, including a top opening groove, wherein the bottom opening groove and the top opening groove constitute a space intended for a vortex chamber; ;

A main nozzle hole formed through a base wall of the mouthpiece so that the vortex chamber effectively communicates between the combustion chamber and the vortex chamber;

A pair of auxiliary nozzle holes formed through the base wall of the mouthpiece and arranged symmetrically on opposite sides about the central axis of the main nozzle hole,

Each of the auxiliary nozzle holes is arranged to pass through the interior of the virtual first circle having a radius of 70% of the radius (100%) of the virtual second circle around the center of the upper opening groove.

<Example>

In the drawings, like numerals are used to denote like elements, and in FIGS. 1 (B), 3 (B), 7 (B), 8 (B), 9 (B), and 2 (A), only For convenience of illustration, the right side is "front" and the left side is rear .. The first embodiment is shown in Figs. 1 to 6, in which a pair of auxiliary nozzle holes 12 are formed on the central axis 3 of the cylinder 1; It is provided in an upright position in parallel with (), which is the same as the second embodiment shown in Fig. 7, but in the third embodiment shown in Fig. 8 and the fourth embodiment shown in Fig. 9, the auxiliary nozzle holes 12 ) Are each slightly converge or diverge towards its upper open end, a characteristic common to all embodiments is that the auxiliary nozzle hole is spaced apart from the main nozzle hole and on the opposite side about the main nozzle hole. The auxiliary nozzle hole is formed in the front side.

In Fig. 3B, a reciprocating piston 2 is provided in the cylinder 1, in which the piston 2 is lifted along the central axis 3 of the cylinder. The cylinder 1 has the head 5 in which the groove 6 in which the mouthpiece 7 is provided is formed. The groove 6 includes a bottom opening groove 6a, and the mouthpiece 7 includes an upper opening groove 7a. The bottom opening groove 6a and the upper opening groove 7a form a space 8 used as a vortex chamber. The cylinder 1 is provided with a combustion chamber 9 having a main nozzle hole 11 penetrating the mouthpiece 7. The combustion chamber 9 and the vortex chamber 8 communicate with each other through the main nozzle hole 11, which is the main nozzle hole 11 from the combustion chamber 8, as shown in FIG. It is tilted forward towards 8). The mouthpiece 7 has a bottom surface 7d in a plane perpendicular to the central axis 3 of the cylinder 1.

As best shown in FIG. 3B, a fuel jet nozzle 19 and a heat plug 20 are provided towards the vortex chamber 8. The piston 1 is provided with a triangular groove 21 for guiding the gas flow, where the root portion of the groove 21 is located just below the main nozzle hole 11, the most in FIG. 3A. As shown well, the groove 21 gradually expands as it moves away from the main nozzle hole 11, and has a reduced depth, as best shown in FIG. 3 (B).

The principle underlying the combustion chamber 9 in which the vortex chamber 8 is installed is as follows.

In the compression stroke, the piston 2 rises, thereby vortexing inside of it by introducing compressed air into the vortex chamber 8. When the piston 2 reaches top dead center, fuel is injected through the injection nozzle 19. The fuel is mixed with air in the vortex chamber 8, and the fuel and the charge of air are ignited and burned in the chamber 8, resulting in expansion of the volume. This expanded gas enters the combustion chamber 9 through the main nozzle hole 11. The new filling is expanded and rises as it moves away from the main nozzle hole 11 in the triangular groove 21. The fuel contained in the fresh charge is mixed with the air in the combustion chamber 9 and the mixture is ignited and combusted.

Next, the auxiliary nozzle hole 12 is described.

1 (A) to 1 (D), in particular in FIGS. 1 (B) and 1 (D), auxiliary nozzle holes 12 are provided in pairs through the base wall 10 of the mouthpiece 7. . Each of the auxiliary nozzle holes 12 is arranged so as to be symmetrically disposed with respect to the central axis 13 of the main nozzle hole 11 or its extension line 14 in accordance with the shape of the main nozzle hole 11. Off).

1 (A), 1 (B), and 1 (D) show an imaginary circular body 15 (actually a sphere) having a center 7c which is the center of the open end 7b of the groove 7a. . The radius of the open end 7b is assumed to be 100%, and the radius of the circular body 15 is assumed to be 50%. Each of the auxiliary nozzle holes 12 is arranged such that its central axis 12a-12b passes through the sphere 15 or through the circular body 15 as shown in the figure.

The radius of the circular body 15 is preferably 70%, more preferably 60%, most preferably 50%. 1 (A), 1 (B), and 1 (D), the innermost, middle, and outermost circular bodies 15 are shown corresponding to 50%, 60%, and 70%, respectively. The angular positioning of the auxiliary nozzle holes 12 in this range can cause auxiliary air to collect in the center of the vortex chamber 8, allowing most of the air to be discharged through the auxiliary nozzle holes 12, It has been demonstrated in practice that it produces effective vortices in the vortex chamber 8.

FIG. 1A shows, as a preferred embodiment, that the auxiliary nozzle holes 12 are aligned with the circular body 15 having a radius of 50% of the center 12c of the opening end of each auxiliary nozzle hole 12. It is shown that the central axis 12a-12b of 12 can be passed through the center of the vortex chamber 8. In this case, the radius is preferably 70% of the radius (100%) of the open end of the upper opening 7b, more preferably 60%, most preferably 50%.

In FIG. 1A and FIG. 1D, it is assumed that the imaginary reference line 16 extends from the central axis 12a of each auxiliary nozzle hole 12 that determines the position of each hole 12. . That is, each of the auxiliary nozzle holes 12 is arranged such that the central axes 12a-12b coincide with the reference line 16 in all directions as shown in Figs. 1A to 1D.

In this way, the auxiliary nozzle holes 12 are arranged at various angles with respect to the reference line 16 (see Figs. 1B and 1D). If it is disposed at a relatively large angle with respect to the reference line 16, the auxiliary nozzle hole 12 is short in length, thereby reducing the frictional resistance to the flow of auxiliary air passing through the auxiliary nozzle hole. In FIG. 1B, in which the two auxiliary nozzle holes 12 are arranged in a line with the cross section of the mouthpiece 7 viewed from the side, the central axes 12a-12b of the auxiliary nozzle holes 12 are referred to as reference lines. It is preferable to incline 30 degrees or less with respect to (16), and it calls it a "first angle" hereafter. In Fig. 1 (D) where the cross section of the mouthpiece 7 is viewed from the rear, the two auxiliary nozzle holes 12 appear to be aligned side by side, preferably the central axes 12a-12b are inclined at 15 °, This is hereinafter referred to as "second angle". In another preferred embodiment, the first angle is no greater than 15 ° and the second angle is no greater than 8 °; More preferably, the first angle is 8 degrees or less, the second angle is 4 degrees or less, most preferably the first angle is 4 degrees or less, and the second angle is 2 degrees or less.

In the embodiment illustrated in Figs. 1B and 1C, the first angle is 30 degrees, the second angle is 15 degrees, and each angular relationship is indicated by a dashed line.

The size of each auxiliary nozzle hole 12 is determined as follows.

Considering the effective area of the opening end of the main nozzle hole 11 as 100%, the total area of the opening ends of the two auxiliary nozzle holes should be in the range of 3% to 15%; Preferably 4% to 10%; More preferably 6% to 10%; Most preferably it should be in the range of 7% to 9%. In short, the range of 3% to 15%, or preferably 5% to 15%, is effective to evenly reduce the generation of NOx and soot.

The main nozzle hole 11 is comprised as follows.

2 (A) to 2 (D), the main nozzle hole 11 is formed in the main groove 17 along the main groove 17 and along the banks (not shown). And a pair of side grooves 18 in communication. In FIG. 2A, each side groove 18 is formed such that its central axis 18a is slightly behind the central axis 17a of the main groove 17. Further, each side groove 18 is arranged such that its angle of elevation is smaller than 45 ° of the axis 17a.

As best shown in FIG. 1A, the main groove 17 remains the same along its entire length, while each side groove 18 has a main nozzle hole 11 that is wide in width. Gradually toward the depth direction of the slightly narrower. Further, the side grooves 18 and the auxiliary nozzle holes 12 are aligned with each other on the same side around the central axis 13 of the main nozzle hole 11.

4 and 5, the main advantage of the first embodiment is that under the condition that the applied load is the same, environmental pollutants such as NOx and soot in the exhaust gas are reduced, which will be demonstrated below.

It can be seen from FIG. 4 that the first embodiment contains less nitrogen oxides (NOx) than the first comparative example without the auxiliary nozzle holes 12 and the side grooves 18. Therefore, it will be appreciated that the auxiliary nozzle holes 12 and the side grooves 18 are effective in reducing the NOx content.

FIG. 5 shows that the first embodiment includes less NOx and soot than the first and second comparative examples, the second comparative example having an auxiliary nozzle hole corresponding to the auxiliary nozzle hole 12 but with side grooves. We do not have groove corresponding to (18). The comparison between the first and second comparative examples shows that the addition of the auxiliary air auxiliary nozzle holes 12 is effective for reducing NOx and soot. Similarly, a comparison between the first and second comparative examples shows that the side grooves 18 are effective for reducing NOx and soot.

The reduction efficiency of the exhaust gas depends on the area of the open end of the auxiliary nozzle hole 12. 6 (A) to 6 (C), each horizontal axis represents the ratio (%) of the total minimum area of the open end of the auxiliary nozzle hole 12 to the area of the open end of the main nozzle hole 11. )to be. The vertical axis of FIG. 6 (A) shows the fluctuation of NOx amount, the vertical axis of FIG. 6 (B) shows the fluctuation of soot amount, and the vertical axis of FIG. 6 (C) shows the fluctuation of total amount of NOx and soot. As a reference value, each coefficient of variation is calculated based on the amount of NOx and soot generated in the combustion chamber without the auxiliary nozzle hole 12. The reference value is α and the variation is β. If so, the coefficient of variation will be (β-α) / α.

As shown in Fig. 6C, the absolute value of the total reduction rate has a maximum value when the area of the open end of the auxiliary nozzle hole 12 is 7.7%. The absolute value of the reduction rate at this stage is called 100%. In order to increase the reduction rate of the exhaust gas to 98%, the total area of the opening end of the auxiliary nozzle hole 12 should be in the range of 7% to 9%, and if the reduction rate is in the range of 95% to 98%, the total area is It was proved to be in the range of 6% to 10%. If the reduction rate is in the range of 60% to 95%, the total area may be in the range of 3% to 15%. In this range, when the reduction rate exceeds 70%, both NOx and soot begin to decrease, and the total area is in the range of 4% to 10%. As a result, the total area of the opening end of the auxiliary nozzle hole is preferably in the range of 3% to 15%, more preferably 4% to 10%, even more preferably 6% to 10%, and most preferably Will be concluded to be 7% to 9%.

7, 8, and 9, the second, third, and fourth embodiments will be described, respectively.

In the second embodiment shown in Fig. 7, the total area of the open end of the auxiliary nozzle hole 12 is 8% of the area (100%) of the open end of the main nozzle hole 11, and each of the auxiliary nozzle holes is It has an open end of the same area. This embodiment reduces the amount of generation of NOx, soot, or both, as clearly demonstrated by the comparison with the first and second comparative examples.

In the second embodiment, the total area of the open end of the auxiliary nozzle hole 12 is 8% of the area (100%) of the open end of the main nozzle hole 11, and each auxiliary nozzle hole is the open end of the same area. Has The second embodiment reduces the amount of generation of NOx and soot compared to the first and second comparative examples, as clearly shown by the comparison with the first and second comparative examples in FIG. 4.

In the third embodiment shown in FIG. 8, the pair of auxiliary nozzle holes 12 are inclined inward, ie slightly gathered from the combustion chamber 9 toward the vortex chamber 8, which is the combustion chamber 9 and the vortex chamber. In contrast to the first and second embodiments extending vertically between (9). In FIG. 8 (B), the inclination angle is 30 degrees, and in FIG. 8 (D), the inclination angles are 15 degrees toward each other.

In the fourth embodiment shown in Figs. 9A to 9D, as best shown in Fig. 9B, the pair of auxiliary nozzle holes 12 are inclined backwards, and Fig. 9 As shown in (D), it is inclined outward, that is, slightly open from the combustion chamber 9 toward the vortex chamber 8. In FIG. 9 (B), the inclination angle is 30 degrees, and in FIG. 9 (D), the inclination angles are 15 degrees toward each other.

According to the present invention having the above-described configuration, through the vortex chamber combustion chamber of the diesel engine of the improved configuration, it is possible to generate an effective vortex so that air and fuel are well mixed and the fuel is well dispersed within the vortex chamber. In the conventional system, there is an advantage that all of NOx and soot could not be reduced.

Claims (26)

A combustion chamber of a diesel engine, wherein the combustion chamber is defined by a piston, a cylinder, and a cylinder head; A mouthpiece installed in a hole of a cylinder head having a bottom opening groove, including a top opening groove, wherein the bottom opening groove and the top opening groove constitute one space intended for the vortex chamber. mouthpiece); A main nozzle hole formed through a base wall of the mouthpiece to effectively communicate between the combustion chamber and the vortex chamber; A pair of auxiliary nozzle holes formed through the base wall of the mouthpiece and symmetrically disposed opposite the center axis of the main nozzle hole, Each of the auxiliary nozzle holes is arranged so as to pass through the interior of the virtual first cylindrical body having a radius of 70% of the virtual second circular body around the center of the upper opening groove, the vortex chamber combustion chamber of the diesel engine. . The method of claim 1, The first cylindrical body has a radius of 60% of the second circular body, the vortex chamber combustion chamber of the diesel engine. The method of claim 1, The first cylindrical body has a radius of 50% of the second circular body, the vortex chamber type combustion chamber of the diesel engine. The method of claim 3, Each auxiliary nozzle hole is arranged so that its center coincides with a first cylindrical body having a radius of 50% of the second cylindrical body. The method of claim 1, Each auxiliary nozzle hole is arranged so that its central axis passes within an angle range of 0 ° to 30 ° from a reference line that is considered to pass axially through the auxiliary nozzle hole. Type combustion chamber. The method of claim 5, Said angular range is 0 degrees-15 degrees, The vortex chamber type combustion chamber of a diesel engine. The method of claim 1, The vortex chamber combustion chamber of a diesel engine, wherein the total area of the opening end of the auxiliary nozzle hole is in the range of 3% to 15% of the total area of the opening end of the main nozzle hole. The method of claim 7, wherein The vortex chamber combustion chamber of a diesel engine, wherein the total area of the opening end of the auxiliary nozzle hole is in the range of 4% to 10% of the total area of the opening end of the main nozzle hole. The method of claim 1, The main nozzle hole has a main groove and two side grooves communicating with the main groove through the inclined surface, respectively. The vortex chamber combustion chamber of a diesel engine. The method of claim 9, The said side groove is the vortex chamber type combustion chamber of the diesel engine characterized by the center axis | shaft behind the center axis of a main groove. The method of claim 10, Wherein each side groove has a central axis inclined at an angle smaller than the inclination angle with respect to the horizontal plane of the base wall of the mouthpiece. The method of claim 11, The lateral groove is a vortex chamber combustion chamber of a diesel engine, characterized in that the distance therebetween is arranged so as to narrow toward the front end thereof. The method of claim 9, A vortex chamber combustion chamber of a diesel engine, wherein each side groove has a cross-sectional area that gradually decreases toward its front end. The method of claim 9, Each side groove is disposed so that its central axis is parallel to the rear of the central axis of the main groove, the vortex chamber combustion chamber of the diesel engine. The method of claim 1, Each auxiliary nozzle hole is arranged such that its central axis extends within an angle range of 0 ° to 30 ° from a reference line that is considered to pass axially through the auxiliary nozzle hole. Type combustion chamber. The method of claim 15, A vortex chamber combustion chamber of a diesel engine, wherein the total area of the opening end of the auxiliary nozzle hole is in the range of 3% to 15% of the total area of the opening end of the main nozzle hole. The method of claim 15, The main nozzle hole has one main groove and two side grooves which communicate with the main groove through the inclined surface, respectively. The vortex chamber combustion chamber of a diesel engine. The method of claim 17, Each side groove is disposed so that its central axis is parallel to the rear of the central axis of the main groove, the vortex chamber combustion chamber of the diesel engine. The method of claim 1, The auxiliary nozzle hole is a vortex chamber combustion chamber of a diesel engine, characterized in that the central axis is disposed so as to stand upright on the base wall of the mouthpiece. The method of claim 19, A vortex chamber combustion chamber of a diesel engine, wherein the total area of the opening end of the auxiliary nozzle hole is in the range of 3% to 15% of the total area of the opening end of the main nozzle hole. The method of claim 19, The main nozzle hole has one main groove and two side grooves which communicate with the main groove through the inclined surface, respectively. The vortex chamber combustion chamber of a diesel engine. The method of claim 21, Each side groove is disposed so that its central axis is parallel to the rear of the central axis of the main groove, the vortex chamber combustion chamber of the diesel engine. The method of claim 9, A vortex chamber combustion chamber of a diesel engine, wherein each side groove is inclined forward by one elevation from the main combustion chamber to the vortex chamber. The method of claim 9, A vortex chamber combustion chamber of a diesel engine, wherein each side groove is inclined rearward by one elevation from the main combustion chamber to the vortex chamber. The method of claim 1, Said auxiliary nozzle hole is arrange | positioned so that the distance between them may become narrower toward upper open end part, The vortex chamber type combustion chamber of a diesel engine. The method of claim 1, Said auxiliary nozzle hole is arrange | positioned so that the distance between them may become wider toward an upper open end part, The vortex chamber type combustion chamber of a diesel engine.