JP2921328B2 - Engine with swirl chamber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine with a swirl chamber, and more particularly, to an engine with a swirl chamber capable of generating a swirling flow in a swirl chamber to mix air and fuel and to ignite relatively early. .

[0002]

2. Description of the Related Art Among compression ignition type diesel engines,
The engine with a vortex chamber has a higher compression ratio than a direct-injection diesel engine, has less ignition delay, can keep the initial heat generation rate relatively low, can reduce the NOx generation rate, and can reduce the exhaust gas concentration. Made and heavily used. For example,
As shown in FIGS. 13 and 14, the engine with a swirl chamber includes a main chamber C in a cylinder block 1 and a cylinder head 3.
The vortex chamber 4 is provided with a vortex chamber 4 having a vortex chamber center line L3. In this engine, when the piston 6 sliding in the direction of the piston center line L1 in the cylinder block 1 is near the compression top dead center, the main chamber C is formed by the concave portion 7 on the piston top surface Pf of the piston 6.

In the compression stroke, the engine pushes air from the main chamber C on the piston top surface Pf into the vortex chamber 4 through the injection port 5 on the base 2 sandwiched between the main chamber and the vortex chamber 4, thereby causing the vortex flow. At the end of the compression stroke, fuel is sprayed from the injector 9 onto the air that has flowed into the room and has become the vertical swirling flow F.
Then, the fuel spray in the swirl chamber 4 is ignited and combustion expansion starts. The combustion gas which has started the combustion expansion is jetted from the injection port 5 into the main chamber C at a predetermined injection port angle β, diffuses into the air in the same chamber and performs main combustion, and the engine performs a combustion expansion process. Thus, in an engine with a swirl chamber, the swirl chamber 4 mainly promotes the mixing of air and fuel to ignite it,
The main chamber C has a role of smoothly jetting into the main chamber C, and the main chamber C has a role of completely burning the combustion gas ignited in the swirl chamber 4.

The vortex chamber 4 responsible for starting the ignition combustion is
A cylindrical wall surface 402 formed in an annular shape with the upper opening 501 of the nozzle 5 as a center portion, and an upward flow f1 formed following the edge of the cylindrical wall surface 402 opposite to the nozzle 5 and from the upper opening 501 of the nozzle. Semi-spherical dome wall surface 401 that deflects the downward flow f2, and a low wall surface that is formed following the nozzle-side edge of the cylindrical wall surface and deflects the downward flow f2 into a low-wall flow f3 that flows toward the upper opening 501 of the nozzle. 201. The upward flow f1, the downward flow f2, and the low wall flow f3 generated in the vortex flow chamber 4 continuously swirl to form a vertical swirl flow F,
This promotes mixing of air and fuel, and completes ignition relatively quickly. Then, after the engine passes through the compression top dead center, the low wall flow f3 of the combustion gas ignited in the vortex chamber 4 to start combustion expansion is deflected, and the upper opening 501 is opened.
From the lower opening 502 of the nozzle 5 and is injected into the main chamber C at a predetermined nozzle angle β, thereby completing the combustion.

[0005] In particular, as shown in FIG. 13, when the engine reaches the middle stage after the early stage of combustion, the main chamber C is largely formed between the opposed portion of the piston top surface Pf and the piston top surface Pf of the cylinder head 3. The combustion gas ejected from the nozzle 5 at the nozzle angle β advances to the gap area opposite to the nozzle side due to the penetration (penetrating force of the combustion gas injected into the main chamber C), and the air in the main chamber C And the combustion proceeds.

[0006]

However, as shown in FIG. 13, in such an engine with a swirl chamber, it is necessary to accurately generate the vertical swirling flow F of the swirl chamber 4, especially when the engine is operated at a low speed. The swirling energy of the direction swirling flow F is small, and its reinforcement is desired. Further, after elapse of the compression top dead center, the low wall flow f3 portion of the mixture ignited in the vortex flow chamber 4 and started combustion expansion is first deflected and flows into the upper opening 501, and from the lower opening 502. The low wall flow f3 is jetted into the main chamber C at a predetermined jet angle β, and it is necessary to largely deflect the flow direction. For example, also in the case of the engine with a swirl chamber shown in FIG. 13, the deflection angle δ (= 180 ° + (180 ° −β)) is large.
As described above, in the engine with a swirl chamber, it is necessary to largely deflect the low-wall flow f3 to the injection port angle β, and a large loss is caused when the flow direction is deflected. That is, since the low-wall flow portion has a habit (indicated by reference numeral fa in FIG. 14) that tends to be above the upper opening 501 due to inertia, it is necessary to suppress the flow and direct the flow toward the injection port 5, and the flow direction is deflected. It was not done smoothly.

For this reason, in the conventional apparatus, there is a limit in enhancing the penetration of the combustion gas injected from the injection port 5 into the main chamber C at the predetermined injection port angle β (the penetration force of the combustion gas injected into the main chamber C). Was. As a result, mixing with the air in the main chamber C is not sufficiently performed, accurate combustion is not performed, the combustion period is extended, the exhaust gas concentration of the engine cannot be reduced, and the fuel efficiency deteriorates. There was a problem. It is an object of the present invention to accurately generate a swirl flow in a swirl chamber and reduce a flow loss of a combustion gas ejected from a nozzle to a main chamber to improve combustion of an engine to reduce smoke concentration. It is an object of the present invention to provide an engine with a swirl chamber that can improve fuel efficiency.

[0008]

In order to achieve the above-mentioned object, the present invention is directed to a swirl chamber through an orifice on a mouthpiece interposed between the main chamber and the swirl chamber from a main chamber on the top surface of an engine piston. In the engine with a swirl chamber, which injects air into the swirl chamber, generates a swirl flow in the swirl chamber, injects and ignites fuel, and ejects the fuel from the injection port to the main chamber to complete combustion.
The swirl chamber is formed on the cylindrical wall surface formed in an annular shape with the upper opening of the nozzle at the center, and formed at the end of the cylindrical wall opposite to the nozzle, and deflects an upward flow from the nozzle into a downward flow. Dome wall surface to be sprayed
At least in the direction orthogonal to the swirling flow of the upper opening
A downward-flow-deflecting-side low wall formed substantially parallel to the piston top surface over a width equivalent to the length and deflecting the downward flow into a low-wall flow flowing toward the upper opening of the injection port. When,
It is formed on the nozzle end side of the cylindrical wall surface, and is formed on the opposite side to the downward flow deflection side low wall surface with the upper opening of the injection hole interposed therebetween, and is larger than the downward flow deflection side low wall surface with respect to the piston top surface. A pair of upper flow-facing lower wall surfaces formed so as to protrude, and a continuous connection between the lower flow deflecting lower wall surface and the upper flow-facing lower wall surface, and a pair of upper and lower openings formed between the injection ports. And a slope wall surface.

[0009]

In the compression stroke, the pair of inclined wall surfaces can suppress the energy loss of the low wall flow and can flow the low wall flow toward the upward flow deflection side and the low wall surface side, thereby promoting the flow of the swirling flow of the vortex chamber.
In addition, the upper opening edge of the nozzle on the upward flow deflecting side low wall surface side is formed so as to protrude more than the downward flow deflecting side low wall surface, and the length of the downward flow deflecting side low wall surface is at least a direction orthogonal to the swirling flow of the upper opening. Since it is formed substantially parallel to the top surface of the piston over the same width, the upper opening edge of the injection port on the upward flow deflecting side low wall surface side projects more than the downward flow deflecting side low wall surface side. Therefore, in the combustion stroke, the air-fuel mixture flows along the downward-flow-deflecting-side low-wall surface formed substantially in parallel with the piston top surface, so that the air-fuel mixture flows from the upper opening edge of the nozzle on the upward-flow-deflecting-side low-wall surface side. Also, the collision with the inside of the injection hole on the top surface side of the piston suppresses the flow in the swirl chamber, and the low-wall flow of the air-fuel mixture can be smoothly guided into the injection hole.

[0010]

1 is an in-line four-cylinder diesel engine with a swirl chamber engine shown in FIG.
The air flows into the swirl chamber 10 through the nozzle, promotes the mixing of the air and the fuel, and ignites the fuel spray.
The main combustion is completed by ejecting the fuel into the main chamber C. This engine with a swirl chamber has a main chamber C and a swirl chamber 10 as shown in FIG. 1 for each cylinder, and here only the first cylinder is shown. This engine with a swirl chamber has substantially the same configuration as the engine shown in FIG. 13 except for the differences in the shape of each part on the swirl chamber 10, particularly the base 11, and here, A duplicate description of the same part will be omitted.
The main chamber C is composed of the piston top surface Pf and the main chamber C of the cylinder head 3.
And a space divided by the inner wall of the cylinder in the cylinder block 1, and its volume changes according to the vertical movement of the piston 6.

Here , the top surface Pf of the piston 6 is a surface perpendicular to the piston center line L1 in the sliding direction of the piston 6, and the center of the portion a on the top surface Pf facing the injection port 12 and the piston A double vortex-type concave portion 7 is provided around the center line L2 of the nozzle-facing portion connecting the center po (see FIG. 2). The concave portion 7 disperses a part of the combustion gas ejected from the injection port 12 to the left and right bilobal portions 702 by the distributing vertical wall portion 701,
The combustion gas injected into the main chamber C does not concentrate and flow along the center line L2 of the nozzle-facing portion, but acts to disperse the combustion gas over the entire area of the main chamber C. The swirl chamber 10 is recessed in the cylinder head 3 as a bell-shaped space, and its low wall is
The base 11 is formed integrally with the base.

The base 11 is a main chamber C in the cylinder block 1.
The main chamber C and the vortex chamber 10 are communicated with each other through an injection port 12 on the base 11. As shown in FIG. 1, the nozzle 12 formed on the base 11 extends in a state where the longitudinal direction of the nozzle is inclined toward the center of the piston, and the upper opening 121 on the swirl chamber 10 side and the main chamber C side. An orthogonal cross section of the injection port passage between the lower opening 122 and the lower opening 122 has an almost elliptical shape. Further, here, the nozzle angle β on the lower opening 122 side is formed larger than that on the upper opening 121 side, thereby increasing the horizontal (in FIG. 1) velocity conversion efficiency of the combustion gas injected into the main chamber C. This prevents the penetration of the combustion gas in the main chamber C from being lowered.

The swirl chamber 10 is formed to have a swirl chamber center line L3 perpendicular to the piston top surface Pf. The swirl chamber 10 has a cylindrical wall surface 102 formed in an annular shape with the upper opening 121 of the injection port 12 as a center, and a dome wall surface 101 formed following the upper end side of the cylindrical wall surface 102 opposite to the injection port. A downward flow deflecting side low wall surface 111 formed at the lower end side of the cylindrical wall surface 102 at the nozzle end, and an upper opening 121 formed at the lower end side of the cylindrical wall surface 102 at the nozzle end side. The lower wall 1 on the downward deflection side
11 is formed on the opposite side to the lower wall surface 112 on the upstream side.
A pair of sloped walls 113 formed on the left and right edges of the nozzle with the upper opening 121 interposed therebetween;
2. Downstream deflection side low wall 111 and a pair of sloped walls 1
13 and an annular inclined surface 114 disposed between the lower end of the cylindrical wall surface 102.

The swirl chamber 10 receives the upward flow f1 from the upper opening 121 of the injection port during the compression stroke of the engine, and guides the upward flow f1 on the opposite side of the injection port by the annular inclined surface 114 and the cylindrical wall surface 102. , Dome wall 10
1 deflects the upward flow f1 into a downward flow f2, and deflects the downward flow f2 into a low wall flow f3 flowing toward the upper opening 121 of the injection port by the annular inclined surface 114 and the downward flow deflection side low wall surface 111. The direction swirling flow F is generated. The vertical swirling flow F swirls around a line (not shown) perpendicular to the paper surface of FIG. 1 as a vortex center, and the fuel injected from the injector 9 can be agitated with air at an appropriate time by the swirling energy.

Here, the cylindrical wall surface 102 has a vortex chamber center line L
3 and the dome wall surface 101 is formed as a semicircle having a radius R with one point on the vortex chamber center line L3 as the center. As shown in FIGS. 1 and 3, the downward flow deflecting side low wall surface 111 is formed in parallel with the piston top surface Pf and deflects the downward flow f2 into a low wall flow f3 flowing toward the upper opening 121 of the injection port. Upward flow opposite side low wall 1
Numeral 12 is formed in parallel with the piston top surface Pf, and is formed so as to protrude more than the downward flow deflection side low wall surface 111 with respect to the piston top surface Pf. That is, the lower wall of the base 11 has a step in the direction along the center line L2 of the nozzle facing portion, and the lower wall 111 and the lower wall 112 face relative to the piston top surface Pf. Are formed so that the typical distances are different.

Here, as shown in FIG. 4, the distance from the lower wall of the base 11 parallel to the piston top surface Pf, that is, the upward flow from the downward flow deflection side low wall thickness 111 on the downward flow deflection side low wall surface 111 side. The thickness H2 of the upward flow-facing low wall on the facing low wall surface 112 side is set large. Figure 1 is an engine H ₂
/ H ₁ was set to 135.7%. Here, by setting the thickness H2 of the upward flow opposing side low wall to be larger than the thickness H1 of the downward flow deflection side low wall, the projecting wall portion indicated by the symbol h in FIG. Inner wall 1 of the spout
The low wall flow f3 which flows toward the upper opening 121 of the injection port during the combustion stroke of the engine
In the nozzle 12.

A pair of sloped walls 113 formed on the left and right edges of the upper opening 121 of the injection port continuously connects the stepped lower wall 111 on the lower side of the deflection flow and the lower wall 112 on the opposite side of the upward flow. It is formed so as to be inclined with respect to the direction along the center line L2 of the nozzle-facing portion (the horizontal direction in FIG. 4). Here, the inclination angle θ of the slope wall 113 with respect to a plane parallel to the piston top surface Pf is set. The inclination angle θ may be any shape as long as the downward flow f2, the low wall flow f3, and the upward flow f1 can be swirled continuously and smoothly, and may be set in a range of 3 ° to 25 °. desirable. As shown in FIG. 2, the pair of inclined wall surfaces 113 have a substantially crescent shape in a plan view, and are formed so that the outer edges are continuous with the annular inclined surface 114. Is connected so as to form an edge line r that continues along the lateral width B of the injection port 12, and is connected to the upward-flow-facing-side low-wall surface 112 side via a bent edge portion m. Is done.

Such a pair of inclined wall surfaces 113 guide the low wall flow f3 deflected by the downward flow deflecting side low wall surface 111 to the upward flow opposite side low wall surface 112 side, and the upward flow f
1 can be promoted again, and as a result, a decrease in the swirling energy of the vertical swirling flow F can be prevented. 2 and 4, a step is formed between the downward flow deflecting side low wall surface 111 and the inclined wall surface 113 at the position of reference symbol p1.
The step at the position of p1 may be eliminated at the edge of 21 and the inclined wall surface 113 may be formed so as to be directed toward the center of the vortex chamber 10 or inclined.

When each cylinder of the engine with a swirl chamber in FIG. 1 enters the compression stroke, the air in the main chamber C flows upward from the injection port 12 into the swirl chamber 10 as the upward flow f1, and the vertical swirl flow F is generated. This promotes mixing of the fuel and air. At this time, the air from the main chamber C continues to flow in from the injection port 12 as an upward flow f1, and among the vertical swirling flow F generated during this time, the low wall flow f3, in particular, has an energy Low wall surface 11 on the opposite side to upward flow while suppressing loss
2 and can be re-deflected to the upward flow f1 to promote agitation of air and fuel, improve ignitability, and have a relatively low upward-flow-facing-side low wall surface 112 (the conventional low wall thickness of FIG. 4). Accordingly, the space where the fuel particles sprayed by the injector 9 and the air are mixed increases, and the ignitability can be improved from this point as well.

Further, when each cylinder of the engine with a swirl chamber shown in FIG. 1 enters the combustion stroke, the projecting wall h formed on the inner wall surface 123 of the injection port flows toward the upper opening 121 of the injection port. It can work to smoothly guide the wall flow f3 into the nozzle hole 12. For this reason, the direction change of the air-fuel mixture which has ignited and forms the vertical swirling flow F can be efficiently performed, and the penetration of the combustion gas ejected from the injection port 12 to the main chamber C at the predetermined injection port angle θ is enhanced. The transmission of the flame in the chamber C is accurately performed at an early stage, the combustion period is shortened, the exhaust gas concentration of the engine can be reduced, and the fuel efficiency is improved. Next, an example of data during the operation of the engine with a swirl chamber in FIG. 1 is referred to as a gradient type B, an example of data of another embodiment of the present invention is referred to as a gradient type A, and an example of data of a conventional engine is referred to as a reference type. 5 to 11 respectively. Note that the slope type A is another embodiment, the downward flow deflection side of the swirl chamber low wall thickness H1, upflow ratio of opposing lower wall thickness H ₂ / H ₁
= That is set to 114.3% is employed, the reference type is a conventional engine, setting a low wall low wall thickness flat surrounding nozzle hole of the swirl chamber as H ₂ / H ₁ = 100% What was done was adopted.

FIG. 5 shows the difference in the smoke concentration during the no-load operation. It is apparent that the gradient type A and the gradient type B have lower smoke concentration than the reference type. FIG. 6 shows a difference in the amount of hydrocarbon HC emission, and shows a gradient type A and a gradient type B with respect to the reference type.
It is clear that can further reduce hydrocarbon HC.
FIG. 7 shows the difference in the emission amount of nitrogen oxides NO _X , and it is clear that there is almost no difference between the reference type and the gradient type A or the gradient type B. FIG. 8 shows the difference in the amount of particulate PM emitted. The gradient type A and the gradient type B are different from the reference type.
It is clear that can reduce the emission amount of particulate PM. FIG. 9 shows the difference in the amount of carbon monoxide CO emitted, and it is clear that the gradient type A and the gradient type B are larger than the reference type, and the emission amount of carbon monoxide CO can be reduced.

FIG. 10 shows the difference in fuel efficiency according to the difference in engine speed. The gradient type B is at substantially the same level of the fuel efficiency as the reference type, and the fuel efficiency of the gradient type A is particularly excellent. It is clear that. FIG. 11 shows the difference in the smoke concentration according to the difference in the engine speed. In both the gradient types A and B, the smoke concentration can be reduced at low rotation with respect to the reference type. It is clear that the Type A flue gas concentration is reliably reduced. FIG. 12 shows the shape data of the gradient type A and the gradient type B. As is clear from these data, the gradient type A and the gradient type B of the present invention surely show a decrease in the smoke concentration and particulates with respect to the reference type (conventional example).
It was confirmed that HC emission could be reduced.

[0023]

As described above, according to the present invention, in the compression stroke, the pair of sloped walls can promote the flow of the swirling flow of the swirl chamber, so that the frame between air and fuel can be promoted and the ignitability can be improved. can do. In addition, since the upper opening edge of the nozzle on the upward flow deflecting side low wall side protrudes more than the downward flow deflecting side low wall side, during the combustion stroke, the air-fuel mixture flows downward in a direction substantially parallel to the piston top surface. When flowing as a low-wall flow along the deflecting-side low wall surface, it collides with the upper opening edge of the injection port on the upward flow deflecting-side low wall surface side, suppressing the flow in the vortex chamber and reducing the low-wall flow of the air-fuel mixture. It can be guided smoothly into the nozzle. For this reason, the penetration of the combustion gas injected into the main chamber is strengthened, and the transmission of the flame in the main chamber is also performed quickly and accurately, the combustion period is shortened, the smoke concentration of the engine is reduced, and the fuel efficiency is improved. be able to.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a main part of an engine with a swirl chamber according to the present invention.

FIG. 2 is an enlarged sectional view taken along line XX in FIG.

FIG. 3 is a sectional view taken along line YY in FIG. 2;

FIG. 4 is an enlarged sectional view of a base portion of the engine in FIG. 1;

FIG. 5 is a comparison characteristic diagram of smoke concentration when the engine of FIG. 1 and other engines are operated under no load.

6 is a comparative characteristic diagram of hydrocarbon emissions of the engine of FIG. 1 and other engines.

FIG. 7 is a comparative characteristic diagram of nitrogen oxide emissions of the engine of FIG. 1 and other engines.

FIG. 8 is a comparative characteristic diagram of particulate emissions of the engine of FIG. 1 and other engines.

FIG. 9 is a comparison characteristic diagram of carbon monoxide emissions of the engine of FIG. 1 and other engines.

FIG. 10 is a comparison characteristic diagram of fuel efficiency of the engine of FIG. 1 and other engines.

FIG. 11 is a comparison characteristic diagram of smoke emission concentrations of the engine of FIG. 1 and other engines.

FIG. 12 is a diagram illustrating shape data of the engine (gradient type A) and other engines (gradient type B) in FIG.

FIG. 13 is a schematic sectional view of a main part of a conventional engine with a swirl chamber.

14 is a schematic cross-sectional view of a main part of the engine of FIG. 13 during a combustion stroke.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder block 3 Cylinder head 10 Eddy flow chamber 101 Dome wall surface 102 Cylindrical wall surface 11 Cap 111 Downward deflecting side low wall surface 112 Upward flow opposite side low wall surface 113 Slope wall surface 114 Circular inclined surface 12 Injection port 121 Upper opening 122 Lower opening 123 Injection port Inner wall surface h Protruding wall portion f1 Upstream flow f2 Downstream flow f3 Low wall flow F Vertical swirling flow Pf Piston top surface C Main chamber H1 Downflow deflection side low wall thickness H2 Upstream flow opposite side low wall thickness

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F02B 1/00-23/10

Claims (1)

(57) [Claims] An air flows from the main chamber on the top surface of the piston of the engine through the injection port on the mouthpiece sandwiched between the main chamber and the vortex chamber into the vortex chamber, thereby generating a swirling flow in the vortex chamber. In the engine with a swirl chamber that injects, ignites, and injects from the nozzle into the main chamber to complete combustion, the swirl chamber has a cylindrical wall surface formed in an annular shape with the upper opening of the nozzle as a center, and the cylinder A dome wall formed at the end of the cylindrical wall opposite to the nozzle and deflecting an upward flow from the nozzle into a downward flow, and a dome wall at the nozzle end of the cylindrical wall.
At least the length of the upper opening in the direction orthogonal to the swirling flow
A downward-deflection-side low wall surface formed substantially parallel to the piston top surface over the same width as the above, and deflecting the downward flow into a low-wall flow flowing toward the upper opening of the injection port; and the cylindrical wall surface. And is formed on the side opposite to the downward flow deflecting side low wall across the upper opening of the injection port, and is formed so as to protrude more than the downward flow deflecting side low wall with respect to the piston top surface. And a pair of sloped walls formed continuously across the downward flow deflecting side low wall surface and the upward flow opposite side low wall surface and sandwiching the upper opening of the injection port. An engine with a swirl chamber, characterized in that it is provided.