JP2921322B2 - Engine with swirl chamber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a vortex chamber provided in a cylinder head, in which air is introduced from an injection port to generate an air-fuel mixture in the same chamber and ignites the fuel. The present invention relates to an engine with a swirl chamber that is injected into a recess to complete main combustion.

[0002]

2. Description of the Related Art An engine with a swirl chamber, which is one type of compression ignition type diesel engine, has a higher compression ratio and less ignition delay than a direct injection type diesel engine, so that the initial heat generation rate is relatively low. In addition, it is widely used because it can reduce the generation rate of NOx and the concentration of flue gas.

[0003] In an engine with a swirl chamber, when the piston rises in compression, air is sent from a main chamber formed in a cylinder block to a swirl chamber through an injection hole formed in a cylinder head to generate a swirl flow. Fuel is injected to generate an air-fuel mixture, which is ignited, and the air-fuel mixture which explodes and expands is returned from the nozzle to the main chamber to perform main combustion.

[0004] The main chamber is mainly formed from a concave portion formed on the top surface of the piston when the piston is near the compression top dead center. The recess divides the flow into left and right by applying the combustion gas blown from the injection port to a separation wall formed in the gas traveling direction, and vortex flows in a circular diffusion chamber formed on the left and right with the center line of the main chamber as a boundary. Is formed, and air and combustion gas accumulated by compression of a piston are mixed by eddy flow to be mainly combusted.

[0005]

By the way, in an engine having a double eddy current type concave portion, the main flow from the injection port is formed on the branch wall since the combustion of the air-fuel mixture near the compression top dead center is promoted. The main combustion is mainly performed in the concave part by causing the collision to branch right and left and flow into the circular diffusion part.
With such a configuration, the spread of the main flow in the combustion chamber after the piston passes through the compression top dead center is restricted, and the dead air where the air-fuel mixture cannot reach the main chamber space located on the side opposite to the injection port is restricted. There is a problem that zones occur. That is, the conventional engine with a swirl chamber has a tendency to form a dead zone on the top surface of the piston where the air-fuel mixture does not reach, the diffusion amount of the air-fuel mixture is reduced, the smoke concentration is increased, and the fuel efficiency is reduced. Have a problem.

[0006] Further, depending on the structure of the engine and the relationship between the strokes, etc., a piston having a valve recess is formed as follows.
It is expected that the depth of the concave portion formed at the top is deeper than the depth of the valve recess.

[0007]

Accordingly, air is introduced into the swirl chamber from the main chamber on the piston through the nozzle in the cylinder block of the present invention to generate a mixture with fuel, and the mixture is ignited. In the engine with a swirl chamber, in which the main combustion is completed by injecting the gas into the concave portion formed on the top surface of the piston, the concave portion linearly spreads from a portion facing the injection port toward the center of the piston. A diffusion portion which is connected to a substantially vertical guide wall and has a fan shape formed by a bifurcated arc-shaped branch vertical wall which is in contact with the center line of the piston, and shallow from the opposite portion toward the center of the piston. It is formed and has a wedge part whose tip reaches the branch vertical wall.

[0008]

The concave portion is connected to a substantially vertical guide wall extending linearly toward the center of the piston from the side facing the injection port, and is formed into a fan shape from a bifurcated arc-shaped branching vertical wall contacting the center line of the piston. Since a diffusion portion to be formed and a wedge portion formed shallowly from the side facing the injection port toward the center of the piston and having a tip reaching the branch vertical wall,
When the air-fuel mixture ejected to the concave portion descends after passing through the compression top dead center of the piston, the air-fuel mixture flows along the wedge portion toward the center of the piston, and the flow force of the air-fuel mixture flowing along the guide wall increases. The air-fuel mixture flowing along the wedge portion passes through the branch vertical wall and is diffused into the main chamber, is separated into right and left by the branch vertical wall, and is diffused into the main chamber along with the air-fuel mixture flowing along the guide wall.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The engine with a swirl chamber shown in FIG. 2 is an in-line four-cylinder diesel engine, in which air flows from the main chamber C of the engine into the swirl chamber 4 through the injection port 5 to generate an air-fuel mixture. After the air-fuel mixture is ignited, it is injected into the main chamber C from the injection port 5 to complete the main combustion. In this engine with a swirl chamber, the main chamber C as shown in FIG.
And a swirl chamber 4. Here, only the first cylinder is shown. The engine with a swirl chamber communicates with an injection port 5 on a base 2 interposed between a main chamber C in a cylinder block 1 and a swirl chamber 4 in a cylinder head 3, and a piston sliding in the cylinder block 1. When the piston 6 is near the compression top dead center, the recess 7 on the top surface 6a of the piston 6 forms the main chamber C.

The swirl chamber 4 is formed along the center line L2 of the swirl chamber perpendicular to the piston top surface 6a, and deflects the air flow from the injection port 5 by its inner wall to generate a swirl flow F. At the end of the compression stroke, fuel is sprayed from an injector 9 that faces the injection port of the swirl flow F into the swirl chamber 4 to generate an air-fuel mixture.

The air-fuel mixture is ignited by a glow plug (not shown) or its own thermal energy to start combustion and expansion, and the air-fuel mixture that has started combustion and expansion passes from the upper opening 5a to the lower opening 5b of the injection port 5 and passes through the injection port 5b. Is ejected into the main chamber C at a predetermined orifice angle .theta. Formed by the intersection of the center line L3 and the top surface 6a of the piston 6, and diffuses into the air in the same chamber for main combustion.

As shown in FIG. 1, the top surface 6 a of the piston 6 has a valve recess 8, 9 of an intake / exhaust valve (not shown) and an injection port opposing portion connecting the center of the opposing portion a to the injection port 5 and the piston center O. A concave portion 7 having a center line L4 as a center is provided.

The concave portion 7 is connected to a guide wall 70 extending toward the center of the piston 6 from the opposed portion a, and forms a fan-shaped diffusion portion 72 from a branch vertical wall 71 in contact with the piston center line L1. And a wedge 73 extending toward the center of the piston 6.

The wedge portion 73 is, as shown in FIGS.
It is recessed relatively deeply, and in particular, the injection port facing portion a is formed deepest, and its depth is gradually reduced toward the piston center line L1.
The first branch 71A is in contact with the first branch 71A.

On the other hand, as shown in FIG. 4, the diffusion portion 72 has a constant depth, is formed shallower than the wedge portion 73, and is formed deeper than the valve recesses 8 and 9, and has a branch which forms a peripheral edge thereof. The vertical wall 71 and the guide wall 70 are formed substantially vertically.

As shown in FIG. 1, the branch vertical wall 71 is a bifurcated arc wall in contact with the center line L1 of the piston, and the branch portion 71A is curved toward the wedge portion 73. A part of the main flow F1 of the air-fuel mixture is defined as a center line L4
Is formed so as to branch into right and left branch flows F2.

The guide wall 70 is a straight vertical wall which widens from both walls 73b of the wedge portion 73 located on the side of the jet port 5 toward the end of the branched vertical wall 71, and is mainly provided near the jet port facing portion a. The flow F1 is a V-shaped flow F3 flowing along the guide wall 70.

The operation of such an engine with a swirl chamber will be described. In each cylinder of the engine, air in the main chamber C flows upward from the injection port 5 into the vortex flow chamber 4 in the compression stroke, and a swirl flow F is generated.
Mixing with more atomized fuel is promoted. This mixture is ignited relatively quickly in the swirl chamber 4. The air-fuel mixture ignited in the swirl chamber 4 is blown out from the injection port 5 to the main chamber C at an injection angle θ, and is sequentially mixed with the air in the main chamber C to complete the main combustion.

In this case, if the operating state is the initial combustion state,
The air-fuel mixture is blown out from the injection port 5 to the concave portion 7 forming the main chamber C at the injection port angle θ, and the piston top surface 6 immediately after the compression top dead center has passed.
The air-fuel mixture from the injection port 5 is jetted into the concave portion 7 only when the gap between the cylinder head 3 and the cylinder head 3 is slightly formed.
Combustion with air. The piston 6 descends according to the movement process of the engine, and accordingly, the piston top surface 6a
The gap between the cylinder head 3 and the cylinder head 3 increases, and this portion goes from the middle stage to the late stage, which forms the volume of the main chamber C.

When the engine having the fan-shaped concave portion 7 has passed the compression top dead center and has reached the operation range at the beginning of combustion, the ignited mixture from the injection port 5 has a wedge on the piston top surface 6a at the injection angle θ. It collides with the part 73 and is deflected in the direction of the piston top surface 6a and proceeds. At this time, the piston top surface 6a
A part of the air-fuel mixture to be diffused in the direction of
Flows into the diffusion portion 72 as a V-shaped flow F3.

Most of the air-fuel mixture from the nozzle-facing portion a becomes the main flow F1, and along the center line L3 of the nozzle-facing portion, a space portion of the main chamber C opposite to the nozzle-facing portion a, that is, a dead zone. And flows into the cylinder. further,
A part of the air-fuel mixture is divided into left and right branch flows F2 by the branch portion 71A.
At this time, since the diffusion part 72 is formed deeper than the valve recesses 8 and 9, the air-fuel mixture which has become the branch flow F2 is diffused by the diffusion part 7.
Flow well into 2. The air-fuel mixture that has sufficiently flowed into the diffusion unit 72 is combined with the V-shaped flow F3 by the diffusion unit 72 and is diffused throughout the main chamber C. As a result, the combustion time can be shortened by mixing with the air inside the entire cylinder, so that the smoke exhaust concentration can be reduced and the fuel efficiency can be reduced.

Further, since the diffusing portion 72 of the present embodiment has a fan shape, if the volume of the diffusing portion 72 and the volume of the conventional circular diffusing portion Z shown by a two-dot chain line in FIG. 1
Since the hatched portion shown in FIG. 7 decreases in a plane, the depth of the diffusion portion 72 can be increased, and the piston 6 having the valve recesses 8 and 9 can be formed.
In the case of (1), it is possible to prevent inadvertent outflow of the air-fuel mixture into the valve recesses 8 and 9, which leads to a decrease in the space side on the side opposite to the injection port 5, that is, a dead zone.

[0023]

As described above, according to the present invention, the air-fuel mixture jetted from the injection port into the concave portion can be positively flown toward the center of the piston, and the air-fuel mixture flowing into the diffusion portion can be removed.
Since the air-fuel mixture flowing along the substantially vertical guide wall is pushed out of the diffusion section, a dead zone where the air-fuel mixture does not reach in the region between the piston top surface and the cylinder head can be prevented, and as a result, the exhaust gas can be exhausted. Smoke density can be reduced and fuel economy can be improved.

[Brief description of the drawings]

FIG. 1 is a plan view of a piston in an engine with a swirl chamber of the present invention.

FIG. 2 is a schematic sectional view of a main part of an engine with a swirl chamber according to the present invention.

FIG. 3 is a sectional view taken along line BB of FIG. 2;

FIG. 4 is a sectional view taken along line CC of FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder block 2 Cap 3 Cylinder head 4 Swirl chamber 5 Injection port 6 Piston 6a Piston top part 7 Concave part 70 Guide wall 71 Branch vertical wall 72 Diffusion part 73 Wedge part 73a Wedge part tip L1 Piston center line C Main chamber a Opposition to injection port Department

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-6-58149 (JP, A) JP-A-61-1823 (JP, A) JP-A-3-118231 (JP, U) JP-A 61-58231 132433 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) F02B 1/00-23/10

Claims (1)

(57) [Claims] 1. An air flow into a swirl chamber through an injection port from a main chamber on a piston in a cylinder block to generate an air-fuel mixture with fuel, and the air-fuel mixture is ignited and formed on the top surface of the piston. A swirl chamber-equipped engine that completes main combustion by being ejected into a recess to be formed, wherein the recess is connected to a substantially vertical guide wall that extends linearly toward the center of the piston from a portion facing the nozzle. A fan-shaped diffusion portion formed by a bifurcated arc-shaped branched vertical wall that is in contact with the center line of the piston; and a shallow portion formed from the opposed portion toward the center of the piston, and a tip thereof extends to the branched vertical wall. Engine with swirl chamber with a wedge that reaches.