JPH04116222A - Two-cycle diesel engine having sub-chamber - Google Patents

Abstract

PURPOSE:To increase an amount of fresh air supplied to a sub-chamber by opening an injection port of the sub-chamber in the vicinity of a cylinder head inner wall surface, being a portion between a pair of exhaust valves and opposed to an intake valve. CONSTITUTION:A pair of exhaust valves 7 are arranged on one side of a cylinder head inner wall surface 3a, while at least one intake valve 5 is arranged on the other side of the cylinder head inner wall surface 3a. An jetting injection port 10 of a sub-chamber is opened in the vicinity of the cylinder head inner wall surface 3a, being a portion between the paired exhaust valves 7 and opposed to the intake valve 5. Combusted gas is drawn out of the sub-chamber due to the combusted gas abruptly discharged from the exhaust valves 7 at the opening time thereof. A large amount of fresh air is therefore supplied to the sub-chamber.

Description

[Detailed description of the invention] [Industrial application field] The present invention is applied to a two-stroke diesel engine with a pre-chamber.

[Conventional technology]

2 with sub-chamber with air supply valve and exhaust valve installed in the cylinder head
In a cycle diesel engine, a mask wall that covers the intake valve opening on the exhaust valve side is placed in a vertical plane that includes the exhaust valve and the intake valve, and fresh air is circulated in a loop within this vertical plane. The applicant has already proposed a two-stroke diesel engine in which the injection port of the sub-chamber is disposed around the inner wall surface of the cylinder head away from the cylinder head (see Utility Model Application No. 1-9445).

[Problem to be solved by the invention]

However, if the mask wall that covers the intake valve opening on the exhaust valve side is placed in a vertical plane that includes the intake valve and exhaust valve, the fresh air will mainly flow in a loop within this vertical plane. A large amount of burnt gas remains in areas away from the vertical plane. Therefore, if the nozzle of the pre-chamber is arranged around the inner wall surface of the cylinder head away from this vertical plane, a large amount of burnt gas will be sent into the pre-chamber through the nozzle during the compression stroke, and the fresh air in the pre-chamber will be This causes the problem that good ignition and combustion cannot be ensured in the pre-chamber due to insufficient ignition.

[A means to solve problems]

In order to solve the above problems, according to the present invention, a pair of exhaust valves are arranged on one side of the inner wall surface of the cylinder head, and at least one intake valve is arranged on the other side of the inner wall surface of the cylinder head. The nozzle port of the auxiliary chamber is opened at the peripheral part of the inner wall surface of the cylinder head located between the exhaust valves and on the opposite side from the intake valve.

[For production]

The burnt gas in the pre-chamber is sucked out by the burnt gas that rapidly flows out from both exhaust valves when the exhaust valves are opened.

〔Example〕

Referring to FIGS. 1 to 4, 1 is a cylinder block, 2 is a piston that reciprocates within the cylinder block 1, and 3 is a cylinder block.
is a cylinder head, 4 is a combustion chamber formed between the flat top surface of the piston 2 and the flat inner wall surface 3a of the cylinder head 3, 5 is a pair of intake valves, 6 is an intake port, and 7 is a pair of exhaust gases. A valve, 8 is an exhaust port, 9 is an auxiliary chamber, 10 is an injection port of the auxiliary chamber 9 arranged in the same plane as the inner wall surface 3a of the cylinder head 3, and 11 is a fuel injection for injecting fuel into the auxiliary chamber 9. valve,
Reference numeral 12 indicates glow plugs arranged in the subchamber 9, respectively.

As shown in FIGS. 1 and 2, a pair of exhaust valves 7 are arranged on one side of the cylinder head inner wall surface 3a, and a pair of air supply valves 5 are arranged on the other side of the cylinder head inner wall surface 3a. ing. Further, the nozzle 10 of the subchamber 9 is connected to a pair of exhaust valves 7.
It is arranged in the peripheral part of the cylinder head inner wall surface 3a between the pair of intake valves 5 and farthest from the pair.

As shown in FIGS. 2 and 3, the cylinder head 3
A pair of grooves 13 are formed on the inner wall surface 3a of the air supply valve 1, and a valve seat 14 for each air supply valve 5 is arranged in the inner part of these grooves 13. Therefore, when the air supply valve 5 is seated on the valve seat 14, the air supply valve 5 is retracted into the groove 13. The circumferential wall of the concave groove 13 on the exhaust valve 7 side is formed into a cylindrical shape disposed close to the outer circumference of the bulk part of the air supply valve 5, and therefore this cylindrical circumferential wall covers the opening of the air supply valve 5 on the exhaust valve 7 side. A mask wall 15 is formed.

On the other hand, the peripheral wall portion 16 of the groove 13 on the opposite side to the mask wall 15
is formed into a conical shape that expands toward the inside of the combustion chamber 4.

FIG. 5 shows the opening timings of the intake valve 5 and the exhaust valve 7.

As can be seen from FIG. 5, in the embodiments shown in FIGS. 1 to 4, the exhaust valve 7 opens before the intake valve 5 and closes before the intake valve 5.

When the exhaust valve 7 opens, the burnt gas in the combustion chamber 4 is suddenly discharged into the exhaust port 8, causing so-called blowdown. At this time, the burned gas within the combustion chamber 4 moves at high speed within the combustion chamber 4 toward the opening of the exhaust valve 7. By the way, in the embodiment shown in FIGS. 1 to 4, an auxiliary chamber 9 is provided near both exhaust valves 7.
Since the nozzle 10 is arranged, the burnt gas discharged from both exhaust valves 7 flows near the nozzle 10 of the auxiliary chamber 9 at a high speed. As a result, the burnt gas in the pre-chamber 9 is sucked out as shown by the arrow T in FIGS. The amount of fuel gas is reduced.

Next, when the intake valve 5 opens, fresh air starts flowing into the combustion chamber 4 from the intake port 6. At this time, since the opening of each air supply valve 5 located on the exhaust valve 7 side is covered by the mask wall 15, most of the fresh air flows into the cone on the opposite side of the mask wall 15, as shown by arrow S in FIG. It flows into the combustion chamber 4 along the shaped peripheral wall section 16 . The fresh air then descends along the inner wall of the cylinder, then along the top surface of the piston 2, crosses the top surface of the piston 20, and then rises again along the inner wall of the cylinder, so that a strong loop is formed in the combustion chamber 4. A scavenging air flow S is generated. The burnt gas in the combustion chamber 4 is sequentially pushed out into the exhaust port 8 via the exhaust valve 7 by this loop scavenging air flow S. At this time as well, the burned gas flows near the nozzle 10 of the auxiliary chamber 9 at a high speed, so that the burned gas in the auxiliary chamber 9 is further sucked out.

On the other hand, since the fresh air is made to rise along the inner wall surface of the cylinder below the exhaust valve 7 as shown by the arrow S in FIG.
Fresh air is gathering below.

Therefore, when the compression stroke is started, fresh air is forced into the auxiliary chamber 9 through the injection port 10. In this way, sub-chamber 9
After the burnt gas inside is sucked out, fresh air is forced into the auxiliary chamber 9, so a large amount of fresh air is supplied into the auxiliary chamber 9. The fuel injected into the tank is successfully ignited and combusted.

〔Effect of the invention〕

By sucking out the burnt gas in the pre-chamber by the burnt gas flow toward the exhaust boat, the amount of fresh air supplied to the pre-chamber can be increased, and thus the fuel can be ignited and burned in the pre-chamber in a good manner.

[Brief explanation of drawings]

Figure 1 is a plan sectional view of the cylinder head of a two-stroke diesel engine, Figure 2 is a bottom view of the cylinder head, Figure 3 is a sectional view taken along line I-I in Figure 1, and Figure 4 is a cross-sectional view of the cylinder head. 1
FIG. 5 is a sectional view taken along the line IV-IV in the figure, and is a diagram showing the opening timings of the air supply valve and the exhaust valve. 5... Air supply valve, 7... Exhaust valve, 9... Sub-chamber, 1
0...Nozzle, 15...Mask wall. Diagram

Claims (1)

[Claims] A pair of exhaust valves are arranged on one side of the inner wall surface of the cylinder head, and at least one air supply valve is arranged on the other side of the inner wall surface of the cylinder head, and the side between the pair of exhaust valves and opposite to the air supply valve is arranged. A two-stroke diesel engine with a pre-chamber in which the pre-chamber nozzle is opened around the inner wall of the cylinder head.