JP2005232987A - Subsidiary chamber type engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a subsidiary chamber type engine having improved combustion efficiency by sufficiently mixing flame jet injected from an injection hole with new air in a main chamber even when the subsidiary chamber is smaller to suppress the production such as NOx and heat loss. <P>SOLUTION: In the subsidiary chamber type engine, new air sucked into the main chamber is compressed with the rise of a piston, the compressed new air is forced to flow into the subsidiary chamber via the injection hole 21 opening to the main chamber, a mixture of the new air flowing into the subsidiary chamber and fuel supplied to the subsidiary chamber is burnt in the subsidiary chamber, and the flame jet F is injected from the subsidiary chamber via the injection hole 21 into the main chamber. A injecting direction Y of the flame jet F via the injection hole 21 corresponds to the swirling direction around an axial center X of the main chamber. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention compresses fresh air sucked into the main chamber by raising the piston, causes the compressed fresh air to flow into the sub chamber through the injection hole that opens into the main chamber, and flows into the sub chamber. The present invention relates to a sub-chamber engine in which a mixture of fresh air and fuel supplied to the sub chamber is combusted in the sub chamber, and a flame jet is injected from the sub chamber into the main chamber through the injection hole.

Conventional engines can be broadly divided into single-chamber type and sub-chamber type. The sub-chamber engine includes a main chamber that is in contact with the top of the piston and a sub-chamber that communicates with the main chamber via an injection hole as a combustion chamber. The compressed fresh air flows into the sub chamber through the injection holes, and the fuel supplied directly to the sub chamber is burned using the fresh air that has flowed into the sub chamber. It is comprised so that a flame jet may be injected into a main chamber via the injection hole opened to a chamber (for example, refer patent documents 1-3).
Further, such a sub-chamber engine can achieve high efficiency because lean combustion in which fuel is burned in a state where the fuel is lean relative to air in the entire combustion chamber can be realized as compared with a single-chamber engine. In particular, it has been introduced into cogeneration systems and the like that require improved efficiency.

JP 2002-276474 A JP 2001-303958 A JP 2001-263069 A

  In the sub-chamber engine as described above, since the air-fuel mixture having a relatively high fuel burns in the sub-chamber, the combustion temperature in the sub-chamber becomes high and NOx may be easily generated. Further, by providing the sub chamber, the surface area of the entire combustion chamber becomes larger than that of the single chamber type, and heat loss due to the surface of the combustion chamber may increase. In other words, it is desired that the sub-chamber of the sub-chamber engine is made small to suppress NOx generation and heat loss.

  However, in the sub-chamber engine, if the sub-chamber is made small, the scale of the flame jet injected from the injection hole into the main chamber also becomes small, and unburned components in the flame jet injected from the injection hole in the main chamber are reduced. Insufficient combustion due to the fresh air present in the main chamber. Furthermore, if a lean air-fuel mixture is sucked into the main chamber as new air, the flame jet will sufficiently burn the lean air-fuel mixture in the main chamber. May not be possible, leading to a reduction in combustion efficiency.

  The present invention has been made in view of the above-mentioned problems, and the purpose thereof is, for example, a flame jet that is injected from an injection hole in a main chamber even when the sub chamber is made small in order to suppress NOx generation and heat loss. It is in the point which implement | achieves a subchamber engine which can fully mix with fresh air and can improve combustion efficiency.

  In order to achieve the above object, a sub-chamber engine according to the present invention compresses fresh air sucked into a main chamber by raising a piston, and has an injection hole for opening the compressed fresh air into the main chamber. And the air-fuel mixture of the fresh air flowing into the sub chamber and the fuel supplied to the sub chamber is combusted in the sub chamber, and the main chamber is connected to the main chamber through the injection hole. A sub-chamber engine for injecting a flame jet into a chamber, wherein the first characteristic configuration is that an injection direction of the flame jet in the injection hole is a turning direction with respect to an axis of the main chamber .

According to the first characteristic configuration, in the sub-chamber engine, the injection direction of the flame jet from the injection hole is the turning direction with respect to the axial center of the main chamber formed in the cylinder in the cylinder, that is, the flame jet Since the injection hole is formed so that the injection direction of the nozzle is twisted with respect to the axis of the main chamber, the flame jet injected from the injection hole can be swung around the axis of the main chamber it can. Then, by rotating the flame jet around the axis of the main chamber, the flame jet mixes well with the fresh air in the main chamber, and the unburned components in the flame jet are improved by the fresh air present in the main chamber. Further, the lean air-fuel mixture existing in the main chamber as fresh air can be burned well by the flame jet, and as a result, the combustion efficiency can be improved.
Therefore, according to the present invention, for example, even when the sub chamber is made small to suppress generation of NOx and heat loss, the flame jet and fresh air injected in the swirling direction from the injection hole to the axis of the main chamber in the main chamber. Thus, it is possible to achieve a sub-chamber engine that can sufficiently improve the combustion efficiency.

  The second characteristic configuration of the sub-chamber engine according to the present invention is such that an intake port for introducing fresh air into the main chamber is formed as a swirl port for generating a fresh air swirling flow in the main chamber, The flame jet is injected in a direction along the swirl flow of the fresh air.

  According to the second characteristic configuration, the fresh air is sucked from the intake port formed as the swirl port, so that a swirling flow around the axis of the fresh air can be generated in the main chamber, and the flame in the injection hole By setting the jet direction of the jet along the fresh air swirl flow, the flame jet injected into the main chamber swirls the main chamber together with the fresh air swirl flow. It is possible to mix the gas and the combustion efficiency more efficiently.

  According to a third characteristic configuration of the sub-chamber engine according to the present invention, a plurality of the injection holes are dispersedly arranged around the axis of the main chamber, and the injection direction of the flame jets of the plurality of injection holes is the main chamber. The swiveling directions are the same as each other with respect to the axis.

  According to the third characteristic configuration, the injection direction of the flame jet in each of the plurality of injection holes distributed around the axis of the main chamber is the same swirl direction with respect to the axis of the main chamber. As a result, a powerful swirl of the flame jet can be generated in the main chamber by each flame jet ejected from the plurality of injection holes. It is possible to mix the gas more satisfactorily, and the combustion efficiency can be further improved.

  A fourth characteristic configuration of the sub-chamber engine according to the present invention is that the fuel is gaseous fuel.

  According to the fourth characteristic configuration described above, the sub-chamber engine can be used in the latter half of the intake stroke or the first half of the compression stroke even when gaseous fuel that is highly compressed and difficult to be injected into the combustion chamber is used as fuel. Fuel can be supplied to the sub chamber at a time when the pressure in the combustion chamber is relatively low, and the fuel can be held well in the sub chamber, and combustion is performed while stably burning a relatively rich mixture in the sub chamber. Lean combustion in which fuel is burned in a state where the fuel is lean relative to air as a whole chamber can be realized, and high efficiency can be achieved.

An embodiment of a sub-chamber engine according to the present invention will be described based on the drawings.
A sub-chamber engine 100 shown in FIG. 1 includes a piston 2 and a cylinder 3 that houses the piston 2 and forms a main chamber 1 together with the top surface of the piston 2, and reciprocates the piston 2 in the cylinder 3. The intake valve 4 and the exhaust valve (not shown) are opened and closed to take in fresh air into the main chamber 1, and various strokes of intake, compression, combustion / expansion, and exhaust are performed in the main chamber 1, and the piston 2 reciprocates. The movement is output as a rotational movement of a crankshaft (not shown) by a connecting rod (not shown), and such a configuration is not different from a normal four-stroke internal combustion engine.

In the sub-chamber engine 100 of the present embodiment, the bore diameter of the cylinder 3 is 110 mm, the stroke length of the piston 2 is 106 mm, and the minimum combustion chamber volume when the position of the piston 2 is the top dead center position The compression ratio, which is the maximum combustion chamber volume ratio when the piston 2 is at the bottom dead center position, is 17, and the displacement obtained by subtracting the minimum combustion chamber volume from the maximum combustion chamber volume is 1007 cc (1007 × 10 7 ³ mm ³ ). The sub-chamber engine 100 is operated at a crankshaft rotation speed of 1200 rpm.

  The sub-chamber engine 100 uses city gas (13A), which is a gaseous fuel, as the fuel G. The intake valve 4 is opened in the intake stroke, and air and a small amount of fuel G are placed in the main chamber 1. The fresh air I which is a lean air-fuel mixture is sucked, and the sucked fresh air I is compressed and the fuel G is combusted in the compression stroke.

The cylinder head 9 of the sub chamber type engine 100 is provided with a main chamber 1 as a combustion chamber, and is provided with a sub chamber 11 communicating with the main chamber 1 through a communication passage 20. The structure of the chamber mechanism 10 will be described below.
The volume of the sub chamber 11 is about 1/10 of the total combustion chamber volume that is the sum of the volumes of the main chamber 1 and the sub chamber 11 when the position of the piston 2 is top dead center. (7 × 10 ³ mm ³ ).

  A so-called deep dish-shaped recess 2 a is formed at the center of the top surface of the piston 2. By forming the recess 2a as described above, squish flowing from the outer peripheral portion of the top surface of the piston 2 to the center of the recess 2a is generated when the piston 2 rises during the compression stroke.

Above the sub chamber 11, a fuel supply valve 30 capable of supplying the fuel G to the sub chamber 11 with a supply pressure of 0.2 MPa (Gauge) is provided.
Furthermore, a spark plug 32 capable of spark ignition of the air-fuel mixture in the sub chamber 11 is provided above the sub chamber 11.

  The sub-chamber engine 100 employs the above-described configuration to compress the fresh air I sucked into the main chamber 1 by ascending the piston 2, and the compressed fresh air I into the main chamber 1. An air-fuel mixture of fresh air I flowing into the sub chamber 11 and the fuel G supplied to the sub chamber 11 by the fuel supply valve 30 in the sub chamber 11 is opened in the sub chamber 11 via the open communication passage 20. 32 is configured to be ignited by a spark and burned to inject a flame jet F from the sub chamber 11 into the main chamber 1 via the communication passage 20. This will be described below.

As shown in FIG. 3, in the sub-chamber engine 100, first, the intake valve 4 is opened, and the piston 2 is lowered from TDC (top dead center). An intake stroke is performed in which the air is inhaled.
At this time, the fuel supply valve 30 installed in the sub chamber 11 is opened at a time slightly delayed from the opening timing of the intake valve 4, and the supply of the fuel G to the sub chamber 11 is started.

  Later, the intake valve 4 and the fuel supply valve 30 are closed at the same time, and a so-called compression stroke is performed in which the fresh air I sucked into the main chamber 1 is compressed by the rise of the piston 2.

  Note that when the sub chamber 11 in the initial stage of the compression stroke is still in a low pressure state, the fuel supply valve 30 may be opened to supply the fuel G to the sub chamber 11.

  By supplying the fuel to the sub chamber 11 in this way, a part of the fuel G supplied to the sub chamber 11 flows out to the main chamber 1 through the communication passage 20. Since the cross-sectional area ratio is set to be extremely small, the outflow amount is about 5% of the total sub chamber fuel supply amount supplied to the sub chamber 11.

In the next compression stroke, as the piston 2 moves up, the volume of the main chamber 1 decreases and the fresh air I in the main chamber 1 flows into the sub chamber 11 through the communication passage 20. A new airflow is generated upward from 20, and the new airflow reaches the ignition region of the spark plug 32.
Therefore, in the ignition region of the spark plug 32 in the sub chamber 11, the fresh air I and the fuel G are mixed to form an air-fuel mixture having an equivalent ratio within the spark ignition possible range.

In this compression stroke, the communication passage 20 works like a so-called throttle valve, and the pressure in the main chamber 1 becomes a pressure substantially equal to the compression ratio, but the maximum ultimate pressure in the sub chamber 11 is the maximum ultimate pressure in the main chamber 1. It will be lower than the pressure.
Therefore, at the end of the compression stroke, the sub-chamber 11 has an air-fuel mixture with an equivalence ratio of about 1.0 to 1.6, preferably about 1.3 to 1.5 in a relatively low pressure field. In the main chamber 1, an air-fuel mixture having an equivalence ratio of about 0.4 to 0.55, and preferably an equivalence ratio of about 0.45 to 0.50 exists in a relatively high pressure field. . As the equivalent ratio of the air-fuel mixture formed in the sub chamber 11 is increased from the theoretical equivalent ratio, the NOx generation amount in the sub chamber 11 can be reduced, and the sub chamber 11 with respect to the fuel supply amount to the main chamber 1 is reduced. By increasing the ratio of the amount of fuel supplied to the fuel, the air-fuel mixture combusted in the main chamber 1 can be diluted to further reduce NOx.

  The sub-chamber engine 100 operates the spark plug 32 in the vicinity of 10 ° BTDC to spark-ignite and burn the air-fuel mixture formed in the sub-chamber 11.

  Then, since the pressure in the sub chamber 11 is the same as that of a normal SI engine, the combustion proceeds without a rapid pressure increase, and the flame jet F passes through the communication path 20 together with the fuel G not combusted in the sub chamber 11. Through the main chamber 1.

On the other hand, in the main chamber 1, the lean air-fuel mixture is burned by the flame jet F ejected from the communication passage 20 in a high pressure field. Combustion to become NOx is performed.
Although the combustion state in the main chamber 1 is a state close to that of a normal SI engine, knocking does not occur even when the compression ratio is set high, so that the thermal efficiency can be improved. Further, even when the equivalent ratio of the fresh air I sucked into the main chamber 11 is increased and the output is increased, knocking can be avoided well, so that the equivalent ratio at the knocking limit can be increased. A wide output adjustment range can be ensured.
Further, since the sub-chamber 11 is set on the side where the equivalence ratio of the air-fuel mixture is high and the main chamber 1 is set on the lean side of the air-fuel mixture, NOx can also be suppressed.

  In the sub-chamber engine 100 operated in this way, the communication passage 20 that communicates the sub-chamber 11 and the main chamber 1 is connected to the axis (from the sub-chamber 11 to the main chamber 1 as shown in FIG. 2). The axial center of the piston 2) extends in the shape of a cylinder having the same axis as the main chamber 1 and has a communication passage 20 extending in the circumferential direction around the axis X of the main chamber 1. There are four cylindrical injection holes 21 that are distributed at regular intervals and open to the main chamber 1, and the flame jet F is injected from the respective injection holes 21 into the main chamber 1 along the axial direction of the injection hole 21. Is done.

Further, each injection hole 21 is formed such that the injection direction Y of the flame jet F in the injection hole 21, that is, the cylinder axis direction of the injection hole 21 is the turning direction with respect to the axis X of the main chamber 1. Specifically, the axis of the injection hole 21 does not intersect the axis of the main chamber 1 and is not balanced, for example, a tangential direction of a circle centered on the axis of the main chamber 1 Yes.
Therefore, since the flame jet F injected from the injection hole 21 in the combustion expansion stroke turns around the axis X of the main chamber 1, the flame jet F is a lean mixture that is fresh air of the main chamber 1. The unburned components and the lean air-fuel mixture in the flame jet F are burned well by the air present in the main chamber 1.

  Furthermore, the injection direction Y of the flame jet F in each of the four injection holes 21 is the same turning direction with respect to the axis X of the main chamber 1, and each of the injections from the four injection holes 21 is performed. The flame jet F becomes a swirl flow of the powerful flame jet F in the main chamber 1 and is mixed with the fresh air I better, and the combustion efficiency is further improved.

The intake port 5 for introducing the fresh air I of the sub-chamber engine 100 into the main chamber 1 is configured as a swirl port for generating a swirling flow of the fresh air I in the main chamber 1, and further, a flame jet in the injection hole 21. The injection direction Y of F is a direction along the swirl flow of the fresh air I.
That is, since the flame jet F injected into the main chamber 1 swirls in the main chamber 1 together with the swirling flow of the fresh air I, the flame jet F and the fresh air I are mixed better, and the combustion efficiency is further improved. Has been improved.

[Another embodiment]
(1) In the above-described embodiment, the injection direction Y of the flame jet F in the injection hole 21 is a tangential direction of a circle centered on the axis of the main chamber 1, and the direction along the swirl flow of the fresh air I Although the injection hole 21 is formed as described above, even if the shape of the injection hole 21 is appropriately modified under the condition that the injection direction of the flame jet F in the injection hole 21 is the turning direction with respect to the axis X of the main chamber 1. I do not care.
For example, by forming the injection hole 21 so that the injection direction Y of the flame jet F is slightly inclined toward the piston 2 (downward) from the tangential direction of the circle centering on the axis of the main chamber 1, It is possible to prevent heat loss from occurring when the flame jet F contacts the wall surface of the cylinder head 9. Further, by forming the injection hole 21 so that the jet direction Y of the flame jet F is opposite to the swirl flow of the fresh air I, the flame jet and the fresh air I can collide and be mixed. .

(2) In the above embodiment, the sub-chamber engine 100 is configured as a spark ignition type equipped with the spark plug 32, but separately configured as a diesel type that does not include the spark plug 32 and self-ignites the air-fuel mixture. You can also That is, the diesel sub-chamber engine injects an auxiliary combustor such as light oil having higher ignitability than the fuel G into the air-fuel mixture formed in the sub-chamber 11 at the end of the compression stroke, and self-ignites and burns it. A flame jet is injected from the injection hole 21 into the main chamber 1.

(3) The sub-chamber engine according to the present invention exhibits an excellent effect when using a gaseous fuel such as city gas as described in the above-described embodiment, and as such a gaseous fuel, In addition to the above-mentioned city gas, there are gaseous fuels other than hydrocarbons mainly containing CO and H ₂ such as hydrogen and propane. In addition, the sub-chamber engine according to the present invention can of course use a fuel other than the gaseous fuel, for example, gasoline, alcohol, methanol, ethanol, or any fuel.

Schematic diagram of sub-chamber engine The figure which shows the formation state of an injection hole Time chart showing the operating state of the sub-chamber engine

Explanation of symbols

1: Main chamber 5: Intake port 10: Sub chamber mechanism 11: Sub chamber 20: Communication passage 21: Injection hole 30: Fuel supply valve 32: Spark plug 100: Sub chamber type engine X: Center Y: Injection direction

Claims (4)

The fresh air sucked into the main chamber is compressed by the rise of the piston, and the compressed fresh air is caused to flow into the sub chamber through the injection holes that open to the main chamber, and the fresh air that has flowed into the sub chamber A sub-chamber engine that burns an air-fuel mixture with fuel supplied to the sub-chamber in the sub-chamber and injects a flame jet into the main chamber from the sub-chamber via the injection holes;
A sub-chamber engine in which an injection direction of the flame jet in the injection hole is a turning direction with respect to an axis of the main chamber. An intake port that introduces fresh air into the main chamber is formed as a swirl port that generates a swirling flow of fresh air in the main chamber,
The sub-chamber engine according to claim 1, wherein an injection direction of the flame jet in the injection hole is a direction along the swirling flow of the fresh air. A plurality of the injection holes are dispersedly arranged around the axis of the main chamber,
The sub-chamber engine according to claim 1 or 2, wherein an injection direction of the flame jet of the plurality of injection holes is a turning direction in the same direction with respect to an axis of the main chamber.   The sub-chamber engine according to any one of claims 1 to 3, wherein the fuel is gaseous fuel.

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