JPS61145317A - Combustion chamber in auxiliary chamber type internal combustion engine - Google Patents

Abstract

PURPOSE:To reduce a constriction loss through the jet port of an auxiliary chamber and further to ensure a sufficient combustion rate to promote later stage combustion, by forming the jet port of the auxiliary chamber with several stage jet port sections, and by setting the minimum areas at the top dead centers of the jet ports sections and the angles of upper and lower parallel surfaces of the jet port sections in specific orders. CONSTITUTION:The variable jet port of an auxiliary chamber is formed such that a projecting part 10 of a piston 7 which ascends is inserted into the jet section of lower part of a nozzle section 9 in the auxiliary chamber to form a jet port. Further, gas is jetted from an auxiliary combustion chamber 2 to a main combustion chamber 1 upon compression and from the main combustion chamber 1 to the auxiliary combustion chamber 2 upon expansion with suitable speeds and directions, respectively. At this time the angles alpha, beta of jet port sections A, B and areas FJAO, FJBP are selected as alpha<beta, FJAO<=FJBO. Then, the flow area FJ from the auxiliary combustion chamber 2 to a main combustion chamber 1 is not abruptly enlarged upon descent of the piston so that a suitable constriction may be held to ensure a sufficient jet stream speed. Accordingly, the later half combustion rate is sufficiently ensured to realize a satisfactory combustion performance.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a combustion chamber of a pre-chamber engine.

[Conventional technology]

A conventional variable pre-chamber nozzle combustion chamber is shown in FIG. In the figure, the sub-combustion chamber 2 is recessed within the cylinder head 4.

Further, the sub-combustion chamber 2 is located away from the cylinder center line B-B and near the cylinder 8. The shape of the auxiliary combustion chamber 2 includes a hemispherical upper part and a truncated conical or cylindrical lower part.

The lower part is a truncated cone. Fuel injection valve 5 in the auxiliary combustion chamber 2
A glow plug 6 for preheating the inside of the sub-combustion chamber 2 at the time of starting the engine is installed as necessary. The auxiliary combustion chamber 2 is the auxiliary chamber cap 9
The top surface of the piston 7 and the cylinder 8. It communicates with the main combustion chamber 1 formed from the lower surface of the cylinder head 4. A protrusion 10 is provided on the top surface of the piston 7.
is installed and the piston is located near top dead center.

The protrusion 10 is inserted into the subchamber nozzle 3. Subchamber spout 3
A notch 11 is formed as necessary near the opening on the sub-combustion chamber side of the nozzle passage wall located away from the cylinder center line B-B.
will be established. Sub-combustion chamber center line A-A and cylinder center line B-
Sub-chamber nozzle 3 at a cut plane of the sub-chamber nozzle 3 by a plane including B
Among the ridgelines, the ridgeline located on the cylinder centerline BB side is parallel to the ridgeline on the cylinder centerline BB side among the ridgelines of the protrusion 10 on the cut surface of the protrusion 10 on the same plane ( α1=αR).

During the compression stroke during engine operation, the main combustion chamber 1 is
The air inside is compressed and flows into the sub-combustion chamber 2 through the sub-chamber nozzle 3 to generate a vortex S. On this occasion.

In areas other than near the top dead center of the compression stroke, the subchamber nozzle area is very large, so the gas inflow velocity from the main combustion chamber 1 to the subcombustion chamber 2 is small. Since the protrusion 10 installed in the sub-chamber nozzle 3 is inserted into the sub-chamber nozzle 3 provided on the sub-chamber mouthpiece 9, the area of the sub-chamber nozzle becomes small and the gas inflow speed from the main combustion chamber 1 to the sub-combustion chamber 2 is reduced. ,
The vortex velocity therefore increases. When fuel is injected through the fuel injection valve 5 along the direction of the vortex S, the fuel swirls in the auxiliary combustion chamber 2 along with the vortex S, mixing the fuel and air, and igniting the fuel.
Burn. Combustion gas in sub-combustion chamber 2.

The unburned fuel is ejected into the main combustion chamber 1 through the pre-chamber nozzle 3,
While doing work to the piston, it simultaneously mixes with the air in the main combustion chamber 1 and causes combustion. That is, the jet flow flowing out from the sub-combustion chamber 2 reaches the wall of the cylinder 8 on the opposite side of the sub-combustion chamber 2 with respect to the cylinder center line BB, and collides with the wall surface. After the collision, the particles disperse along the wall surface of the cylinder 8 wall. This is because the protrusion 10 is inserted into the subchamber nozzle 3 near the top dead center.

The sub-chamber nozzle area is relatively small, and the gas in the sub-combustion chamber 2 is ejected into the main combustion chamber 1 at high speed. piston.

Therefore, as the protrusion 10 further descends, the subchamber nozzle area becomes larger and the injection speed into the main combustion chamber 1 becomes smaller.

[Problem that the invention seeks to solve]

The above has the following drawbacks. In a conventional diesel engine with a variable pre-chamber nozzle combustion chamber shown in Figure 4, the nozzle area expands as the piston descends, causing gas to flow from the sub-combustion chamber to the main combustion chamber, which is a drawback of pre-chamber diesel engines. This has the advantage that the constriction loss of the dam is greatly reduced.

However, in the case of a nozzle with a simple parallel plane as shown in Figure 4,
As shown in Fig. 5(b), the nozzle opening opens rapidly as the piston descends, and as a result, the jet velocity from the auxiliary combustion chamber to the main combustion chamber is too slow, and after 30° the piston descends rapidly. Combustion becomes slow, which actually causes a deterioration in combustion efficiency, leading to a deterioration in fuel efficiency.

In addition, Fig. 5 (a), (
In the case of the nozzle c), the nozzle area F for the piston displacement X
The change in , is not a simple increase as shown in Figure 5(b),
It reaches the maximum area FJmaX and becomes constant. In addition.

In Fig. 5(a), +L = L□ +Xcasα
l FJ = FJO (10 meals/fish α).

[Failure to solve the problem]

The object of the present invention is to provide a combustion chamber for a pre-chamber internal combustion engine that eliminates the above-mentioned drawbacks, and is characterized by:
In an internal combustion engine with a variable pre-chamber nozzle in which a protrusion provided on the top surface of the piston is inserted into an opening provided in the pre-chamber mouthpiece of the sub-combustion chamber when the piston passes near the top dead center to form a pre-chamber nozzle, A and B from the main combustion chamber side to the auxiliary combustion chamber side of the auxiliary chamber nozzle.

C9...X consists of a multi-stage nozzle section, and the minimum area at top dead center of each stage nozzle section is FJAO"
o, and when the angles of the upper and lower parallel surfaces of each stage nozzle port with respect to the plane perpendicular to the cylinder axis are α, β, ... ξ.

FJAO≦FJBo≦...≦FJX.

α くβ く・・・＜ξ It is configured so that.

[For production]

In this case, as the piston displacement X increases, the nozzle area F
J increases, but the rate of increase in area decreases from the middle, and it breaks into multiple stages as shown in FIG. 2(b). As a result, the outflow area from the auxiliary combustion chamber to the main combustion chamber, ie, FJ, does not suddenly expand due to the downward movement of the piston, but maintains an appropriate restriction and maintains a sufficient jet velocity.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing a combustion chamber of one embodiment according to the present invention.

In the figure, 1 is the main combustion chamber, 2 is the sub-combustion chamber, 3 is the sub-chamber nozzle which communicates the main and sub-combustion chambers 1 and 2, 4 is the cylinder head, 5 is the fuel injection valve, 6 is the glow plug for starting, 7 is a piston, 8 is a cylinder, 9 is a sub-chamber mouthpiece, and 10 is a protrusion corresponding to the lower surface of a sub-chamber nozzle provided on the piston 7.

The pre-chamber nozzle 3 is composed of a curved line bent in two stages, and the lower part A of the nozzle is at an angle α of 2 with respect to a plane perpendicular to the cylinder axis.
The plane, upper part B, corresponds to two planes with an angle of β, and the angles of inflow and outflow into the main combustion chamber and into the auxiliary combustion chamber are also different.

The operation in the case of the above configuration will be described.

The variable subchamber nozzle according to the present invention forms a nozzle as shown in FIG. 1 by inserting the protrusion 10 of the piston 7 into the nozzle at the lower part of the subchamber mouthpiece 9 as the piston 7 rises,
During compression, the fuel is ejected from the main combustion chamber 1 to the sub-combustion chamber 2, and during expansion, it is ejected from the sub-combustion chamber 2 to the main combustion chamber 1 at appropriate speeds and directions.

In this case, if the angles α and β of the nozzle A and B parts and the areas FJAo and FJB0 at top dead center are respectively α and β FJAO≦FJBO, then the nozzle area F with respect to the increase in piston displacement
, increases, but the area increase rate decreases midway through, resulting in a two-stage broken characteristic as shown in FIG. 2(b).

As a result, the outflow area F from the sub-combustion chamber 2 to the main combustion chamber 1,
The jet flow does not expand rapidly due to the downward movement of the piston, and maintains an appropriate restriction and maintains a sufficient jet velocity.

Therefore, it is possible to secure a sufficient combustion speed in the latter stage and achieve good combustion performance.

FIG. 3(,) is a sectional view showing a nozzle part of another embodiment according to the present invention.

In the figure, the structure of the variable pre-chamber nozzle near the piston top dead center is composed of three parts A, B, and C, and the minimum area of each part is FJAOj FJBOIFJCO and the angle α with respect to the plane perpendicular to the cylinder axis. , β, and γ are set so that FJAO≦FJBo≦FJCO α×β×r.

As a result, as shown in FIG. 3(b), the piston displacement
FTA I FJB t FJC and FJma
It is possible to change the area of the subchamber orifice using a curve like X.

Appropriate nozzle orifice area is given to piston displacement,
A necessary and sufficient jet velocity can be provided.

Note that parts A, B, and C in Figure 3 (a) are connected with small curves to achieve smooth flow.
If this is further configured in multiple stages, the minimum area F on the main combustion chamber side
JAOl angle α, auxiliary combustion chamber side FJXOl angle ξ.

F　≦・・・　・・・≦FJXO AO- α く・・・　・・・＜ξ A curved variable subchamber nozzle that satisfies the following conditions is constructed.

The same effects as in both of the above embodiments can be obtained.

〔Effect of the invention〕

In the case of both of the above-mentioned embodiments, the effects of the characteristics of the variable pre-chamber nozzle are fully utilized to reduce the throttle loss of the pre-chamber nozzle, and
It becomes possible to secure a sufficient combustion rate and promote late combustion, thereby achieving good thermal efficiency.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a combustion chamber of one embodiment according to the present invention;
FIG. 2(a) is a sectional view showing the pre-chamber nozzle part of the combustion chamber in FIG. 1, FIG. 2(b) is a diagram showing changes in the pre-chamber nozzle area, and FIG. 3(, ) is a diagram showing the present invention. FIG. 3(b) is a diagram showing changes in the area of the pre-chamber nozzle area, and FIG. 4 is a cross-sectional view showing the combustion chamber of a conventional variable pre-chamber nozzle. , FIG. 5(,) is a sectional view showing the pre-chamber nozzle of the combustion chamber in FIG. 4, FIG. 5(b) is a diagram showing changes in the pre-chamber nozzle area, and FIG. FIG. 2 is a sectional view taken along the line A-A in FIG. 1... Main combustion chamber, 2... Sub-combustion chamber, 3... Sub-chamber nozzle. 7...Piston, 9...Sub-chamber mouthpiece, 10...Protrusion. 10.-Tsuma? Sound D'; +1 figure Hi6 stone displacement χ (Upper death stink needle) C name) (d) Hi0 stone stroke (Soil death book series) t, /3) Record 73, Figure 74

Claims (1)

[Scope of Claims] 1. A variable combustion chamber in which a protrusion provided on the top surface of the piston is inserted into an opening provided in the sub-chamber mouthpiece of the sub-combustion chamber when the piston passes near the top dead center to form a sub-chamber nozzle. In an internal combustion engine with a sub-chamber nozzle, the sub-chamber nozzle is composed of multi-stage nozzle sections A, B, C, ...X from the main combustion chamber side to the sub-combustion chamber side, with a The minimum area at the dead center is F_J_A_O, F_
J_B_O, ...F_J_X_O, and when the angles of the upper and lower parallel surfaces of each stage nozzle port with respect to the plane perpendicular to the cylinder axis are α, β, ... ξ, F_J_A_O≦F_
J_B_O≦・・・≦F_J_X_Oα＜β＜・・・・
A combustion chamber of a pre-chamber internal combustion engine, characterized in that it is configured so that ...<ξ.