JPH06341322A - Auxiliary chamber type engine - Google Patents

Abstract

PURPOSE:To provide an auxiliary chamber type engine to improve the thermal efficiency by uniformly distributing the jet of the gas such as flame from a sub-combustion chamber to a main combustion chamber over the whole cylinder to make the jet reach the vicinity of the cylinder in a short time, and reducing the combustion speed in the main combustion chamber. CONSTITUTION:A main combustion chamber 1 is communicated with a sub- combustion chamber 2 arranged on the center axis of the cylinder by a plurality of communicating holes 4. The fuel is sprayed from many jet holes of a fuel injection nozzle 19 in the center of the sub-combustion chamber 2 into the sub- combustion chamber 2. A plurality of the communicating holes 4 are formed at the equal space in the circumferential direction deviated from the center of the sub-combustion chamber 2, and the jet ejected from the sub-combustion chamber 2 to the main combustion chamber 1 is inclined in the direction to follow the suction swirl relative to the cylinder axis. Grooves 9, 19 which are the guide passage of the jet from the communicating holes 4 are formed in the lower surface part of a valve 18 located on the extension line of the communicating holes 4 and in the lower surface part of the cylinder head 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sub-combustion engine having a main combustion chamber, a sub-combustion chamber communicating with the main combustion chamber through a communication hole, and a fuel injection nozzle for injecting fuel into the sub-combustion chamber.

[0002]

2. Description of the Related Art Conventionally, a swirl chamber type engine having a swirl chamber has been developed for the purpose of improving combustion of the engine. Such a swirl chamber engine has a swirl chamber formed in the cylinder head, a communication hole for communicating the swirl chamber with the main chamber formed on the cylinder side, and a fuel injection nozzle arranged in the swirl chamber. A mixture is formed with the fuel injected into the swirl chamber by the swirl flowing into the swirl chamber through the holes.

Further, Japanese Utility Model Laid-Open No. 52-13204 discloses a structure of an auxiliary combustion chamber. The structure of the auxiliary combustion chamber is such that the protruding rod is attached to the piston top part in the main injection hole of the die of the auxiliary combustion chamber and the protruding rod is inserted near the top dead center, and the protruding rod top when the protruding rod is at the uppermost position. A plurality of sub-injection holes, which penetrate the die from the sub-combustion chamber including the main injection holes above the surface and open to the main combustion chamber, are provided.

An example of a conventional diesel engine is disclosed in Japanese Utility Model Laid-Open No. 54-53104. The diesel engine is provided so as to project from a cylinder head into the cylinder, divides the cylinder into two chambers, and has a surrounding wall that can be inserted into and removed from a cavity formed at the top of the piston. A fuel injection nozzle facing one of the chambers, a communication hole communicating with the two chambers, and a communication hole formed in the surrounding wall so as to generate a swirl in the one chamber during the compression stroke of the engine. .

[0005]

Generally, the sub-chamber engine is of a swirl chamber type and has a sub-chamber volume ratio of 52 to 58% and a sub-chamber communication hole area ratio of 1.2 to 1.6%.
To some extent, the single injection hole nozzle optimizes combustion. When the fuel spray and air in the sub-chamber combustion chamber are mixed with each other, the air compressed in the compression stroke passes through the sub-chamber communication hole that serves as a throttle, and the flow velocity of the air increases, which becomes the energy for producing the air-fuel mixture and the fuel spray. It is believed to promote mixing with. Further, it is considered that in the expansion stroke, the combustion gas in the sub chamber and the throttling effect of the sub chamber communication holes serve as energy for ejecting the combustion gas from the sub chamber to the main chamber to promote combustion in the main chamber. In such a sub-chamber engine, the air-fuel mixture generation energy and the jetting energy, which are important for combustion, are formed by the throttle of the sub-chamber communication hole, so the passage area of the communication hole cannot be increased, and therefore the pump Since the loss is large and the air-fuel mixture is generated by vigorous air flow, the thermal conductivity in the sub chamber is large and the cooling water loss is large.

Further, by providing the communication holes for connecting the main chamber and the sub chamber at an angle in the tangential direction of the wall of the sub chamber, the air flow in the sub chamber is activated, and after the ignition, the flame to the main chamber is increased. Since the flame reaches the outermost circumference of the main chamber in a short time without the attenuation of the ejection energy, the air utilization rate is improved, clean combustion with less harmful gas is possible, and the output is also improved. Also,
In the case of a sub-chamber with an inclined sub-communication hole, the velocity of the passing air is the same at the time of inflow and at the time of ejection after ignition, and the ejection energy is When the diameter of the communication hole is reduced in order to increase the height, the air flow, that is, the swirl generated in the sub chamber simultaneously becomes strong.

Further, when the engine is constructed as a sub-chamber type combustion chamber, in order to make the combustion speed of the sub-chamber type combustion chamber as high as that of the direct injection type combustion chamber, It is necessary to increase the passage cross-sectional area of the communication hole that communicates with each other. However, if the passage cross-sectional area of the communication hole is increased, the ejection speed of the gas flowing from the sub chamber to the main chamber is reduced, and combustion in the main chamber is not sufficiently performed.

Further, in the swirl chamber type engine, since the communication hole that connects the sub chamber and the main chamber is small, throttling loss occurs due to the communication hole, which causes a reduction in engine output. Further, in general, since the communication hole that connects the main chamber and the sub chamber is provided at either one of the center portion of the cylinder or the outer peripheral portion, the distance that the jet flow must reach becomes long, Mixing with air in the chamber becomes insufficient, HC,
It causes smoke. Further, since the communication hole is narrowed and formed in an inclined state, the intake air flowing through the intake port forms a swirl flow in the cylinder, but when the swirl flow flows into the sub chamber through the communication hole. However, there is a problem that the energy of the swirl flow cannot be fully utilized in the sub chamber.

Therefore, a communication hole that connects the main chamber and the sub chamber to each other is
By arranging multiple angled tangents to the wall of the sub-chamber, the air flow in the sub-chamber becomes more active, and after ignition, there is no attenuation of the flame ejection energy into the main chamber, and there is no decay in the main chamber in a short time. Since the flame reaches the outer circumference, the air utilization rate improves,
Clean combustion with less harmful gas is possible and output is improved (see, for example, Japanese Patent Application No. 5-46175). In the case of actually designing a sub-chamber engine with a sub chamber of about 2000 cc in which the sub chamber is arranged at the center of the cylinder axis, if the effective area of the valve is set to a large value, it will be
It has to be a valve.

However, when 6 valves are arranged on the lower surface of the cylinder head, the gas such as flame and unburned air-fuel mixture ejected from the sub-combustion chamber to the main combustion chamber through the communication hole is guided. When forming the grooves on the bottom surface, those grooves must be formed on the lower surface portion at a position avoiding the valve. Also, due to the camshaft of the valve operating mechanism of the valve, if the position of the valve is distributed to the left and right, the communication hole must also be formed on the lower surface of the cylinder head at a position corresponding to that, and the formation of the communication hole will occur. Cannot be formed evenly spaced apart in the direction, and the jet flow ejected from the sub-combustion chamber to the main combustion chamber through the communication holes becomes non-uniform in the main combustion chamber, resulting in non-uniform combustion in the main combustion chamber. Occurs.

An object of the present invention is to solve the above-mentioned problems, in which the auxiliary combustion chamber is arranged in the center of the cylinder of the cylinder head, the main combustion chamber is formed on the cylinder side, and the main combustion chamber and the auxiliary combustion chamber are A plurality of communication holes that communicate with each other are provided at equal intervals in the circumferential direction around the cylinder center axis to suppress and optimize the swirl flow in the auxiliary combustion chamber to prevent heat dissipation from the auxiliary combustion chamber to the outside. the throttle loss reduction of with is burned in the fuel-rich to suppress the generation of NO _X, also shortens the reach of the auxiliary combustion chamber to the cylinder periphery of the jet to be ejected into the main combustion chamber through the communication hole, the cylinder It reaches the surroundings in a short time and evenly, ejects it in the intake swirl of the main combustion chamber and in the forward flow direction, and promotes mixing with the fresh air of the main combustion chamber by utilizing the swirl flow existing in the main combustion chamber, Improves performance by shortening the combustion period So, to provide smoke, HC, suppressing generation of NO _X a pre-combustion chamber engine.

[0012]

In order to achieve the above object, the present invention is configured as follows. That is, according to the present invention, the main combustion chamber formed on the cylinder side, the sub combustion chamber arranged in the cylinder head on the cylinder center axis, the plurality of communication holes communicating the main combustion chamber and the sub combustion chamber, and the sub combustion chamber. In a sub-chamber engine having a fuel injection nozzle with an injection hole opened in the center for spraying fuel into the combustion chamber, the communication holes are arranged at equal intervals in a circumferential direction eccentric from the center of the sub-combustion chamber. A valve that is formed and inclined with respect to the cylinder axis in a direction in which the jet flow from the sub-combustion chamber to the main combustion chamber becomes a forward flow to the swirl of the main combustion chamber, and is located on the extension line of the communication hole. The sub-chamber engine is characterized in that a groove that forms a passage for a jet flow from the communication hole is formed in the lower surface portion and the lower surface portion of the cylinder head.

Further, in this sub-chamber engine, the valve is made of a material such as low density and high strength ceramics.

[0014]

The subchamber engine according to the present invention is configured as described above and operates as follows. That is, in this sub-chamber engine, a plurality of communication holes that communicate the main combustion chamber formed on the cylinder side with the sub-combustion chamber arranged on the cylinder head on the cylinder center axis are eccentric from the center of the sub-combustion chamber. A plurality of them are formed at equal intervals in the circumferential direction, and are formed so as to be inclined in a direction in which a jet flow from the sub-combustion chamber to the main combustion chamber is forward to the swirl of the main combustion chamber with respect to the cylinder axis. Since the valve lower surface portion and the cylinder head lower surface portion, which are located on the extension line of the communication hole, are formed with a groove that forms a passage for the jet flow from the communication hole, the auxiliary combustion chamber passes through the communication hole to the main combustion chamber. The jet of flame, unburned air-fuel mixture, etc. ejected to the cylinder reaches the cylinder periphery through the groove in a short period of time, and the jet is evenly distributed to promote uniform mixing with fresh air in the main combustion chamber. Become even. However, by forming the groove on the lower surface of the valve and the lower surface of the cylinder head,
The formation positions of the communication holes can be formed at equal intervals in the circumferential direction. Therefore, the jet flow diffuses uniformly in the main combustion chamber,
It improves the air utilization rate and mixes it evenly with the fresh air in the main combustion chamber, shortens the combustion speed and completes the combustion, and improves the thermal efficiency. Moreover, the uniform combustion makes it possible to reduce smoke, particulates, etc. Occurrence can be suppressed.

Moreover, since at least four communication holes are formed per cylinder and the jetting direction from the auxiliary combustion chamber to the main combustion chamber is inclined so as to be in the same direction as the intake swirl, the auxiliary sub-chamber is formed. The gas of the ejected flame and the unburned air-fuel mixture from the combustion chamber to the main combustion chamber can effectively utilize the intake swirl remaining in the main combustion chamber, and promote the mixing in the main combustion chamber.

Further, in this sub-chamber type engine, the sub-combustion chamber is located at the center of the cylinder, and the communication hole is open to the main combustion chamber in the circumferential direction away from the center of the cylinder. Then, the reaching distance of the jet flow from the communication hole is short, the combustion time is short, and the performance is improved. Also,
Since the jet flow from the sub-combustion chamber can reach a short distance, a plurality of the communication holes can be formed to increase the total passage area, reduce the squeezing loss, and improve the efficiency. Also,
When the inclination direction of the communication hole is inclined outward, the reaching distance of the jet from the auxiliary combustion chamber to the periphery of the piston is further shortened, and the combustion flame and the unburned air-fuel mixture are generated around the piston existing in the main combustion chamber. Promotes mixing with fresh air and increases combustion speed. Therefore, combustion is completed by suppressing the generation of HC, smoke, etc. in the main combustion chamber.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a subchamber engine according to the present invention will be described below with reference to the drawings. 1 is a sectional view showing an embodiment of a sub-chamber engine according to the present invention, FIG. 2 is an explanatory view showing a connecting hole of the sub-chamber engine of FIG. 1, and FIG.
FIG. 3 is a perspective view showing a valve of the sub-chamber engine of FIG.

This sub-chamber engine has a cylinder head 5 fixed to a cylinder block 6 with a gasket 16 interposed, and the cylinder block 6 is formed with holes corresponding to the number of cylinders of the engine. A cylinder liner 13 that forms the cylinder 3 is fitted in. The cylinder head 5 has an intake / exhaust port 17 in which an intake / exhaust valve 18 is arranged. The cavity 11 formed in the cylinder head 5 has a headliner 20 that constitutes the main combustion chamber 1.
Heat shield ring 24 and heat shield gasket 2 positioned by
7, a heat shield air layer 25 is formed between the outer peripheral surface of the headliner and the cavity wall surface. Further, the head liner 20 is configured by integrally forming a head lower surface portion 21 and a liner upper portion 22 formed in a pent roof type, and forms the main combustion chamber 1. Therefore,
The head lower surface portion 21 constitutes a cylinder head lower surface portion in this embodiment. A port 29 communicating with the port 17 formed in the cylinder head 5 is formed in the head lower surface portion 21. The lower surface of the liner upper portion 22 is arranged so as to face the upper surface of the cylinder liner 13, and forms the cylinder 3. A piston 8 is incorporated in the cylinder 3 formed by the cylinder liner 13 and the head liner 20 so as to reciprocate.

The sub-combustion chamber 2 is arranged on the center axis of the cylinder, and is composed of a sub-chamber member 15 arranged in a small-diameter cavity 26 formed in the cylinder head 5 with a heat shield gasket 23 interposed. Has been done. Fuel injection nozzle 1
0 penetrates the upper part of the sub chamber member 15 arranged in the cylinder head 5 so as to inject fuel into the sub combustion chamber 2, and opens multiple injection holes 7 in the center of the sub combustion chamber 2.

In this sub-chamber engine, the main combustion chamber 1
A plurality of (6 in FIG. 2) inclination holes are provided at the lower surface portion 28 of the auxiliary chamber member 15 forming the lower surface portion of the cylinder head, the communication holes 4 communicating between the auxiliary combustion chamber 2 and the auxiliary combustion chamber 2 being evenly spaced in the circumferential direction. Is formed in. The communication hole 4 is formed in the tangential direction of the side wall surface of the auxiliary combustion chamber 2. Moreover, the communication hole 4 is formed in a tangential direction offset from the central axis of the auxiliary combustion chamber 2,
The lower surface 28 of the sub chamber member 15 and the lower surface of the head of the head liner 20 are tilted in a direction in which the jet flow from the sub combustion chamber 2 to the main combustion chamber 1 is in the same direction as the intake swirl IS remaining in the main combustion chamber 1. 21 is formed. Therefore, the communication hole 4
The swirl S formed in the auxiliary combustion chamber 2 by the intake air flowing from the main combustion chamber 1 to the auxiliary combustion chamber 2 is formed in the direction opposite to the intake swirl IS. In this sub-chamber engine, as shown in FIG. 1, a cavity 11 is formed in the cylinder head 5, and the headliner 20 is formed in the cavity 11.
However, without being limited to the embodiment,
Without placing a headliner on the cylinder head 5,
A cavity 26 is formed on the lower surface of the cylinder head 5,
The sub chamber member 15 may be arranged in the cavity 26.

In this sub-chamber engine, a main combustion chamber 1 is formed on the cylinder 3 side, and a sub chamber member 1 forming a sub combustion chamber 2 is formed.
5 is arranged in the cylinder head 5 on the center axis of the cylinder,
Since the multiple injection holes 7 of the fuel injection nozzle 10 spray the fuel into the auxiliary combustion chamber 2, they are opened in the center of the auxiliary combustion chamber 2. In particular,
A plurality of (6 in FIG. 2) communication holes 4 that connect the main combustion chamber 1 and the auxiliary combustion chamber 2 are formed at equal intervals in the circumferential direction that is eccentric from the center of the auxiliary combustion chamber. The jet flow ejected from the auxiliary combustion chamber 2 to the main combustion chamber 1 is formed so as to be inclined in a direction in which the jet flow advances to the intake swirl IC remaining in the main combustion chamber 1. Moreover, on the lower surface of the cylinder head (the head lower surface portion 21 in FIG. 1) located on the extension of the communication hole 4, the groove 9 that forms the passage of the jet flow from the communication hole 4 is formed. Valve 1 located on the extension line of 4
A groove 19 that forms a passage for the jet flow from the communication hole 4 is formed in the lower surface portion of 8. The grooves 9 and the grooves 19, which are evenly distributed in the main combustion chamber 1, are connected to each other.

In this sub-chamber engine, the head lower surface 2
1 and the grooves 9 and 1 formed on the lower surface of the valve 18, that is, the lower surface of the valve umbrella.
For 9, the formation position may be determined under the following conditions. That is, for example, by arranging the auxiliary combustion chamber 2 on the center axis of the cylinder, six valves 18 are provided in the cylinder head 5 in order to secure the intake / exhaust amount. In order to arrange the six valves 18 in the cylinder head 5, it is preferable to form them in the pent roof type main combustion chamber 1. Therefore,
When the head lower surface portion 21 forming the main combustion chamber 1 is formed in a pent roof type, the arrangement position of the valve 18 is determined by the arrangement of the cam shaft of the valve mechanism. On the other hand, the auxiliary combustion chamber 2 is arranged in the center of the cylinder to form the lower surface 12 of the pentroof type head lower surface portion 21, and the auxiliary chamber member 1
A plurality of communication holes 4 are formed in the lower surface portion 28 of No. 5. Moreover, the number of communication holes 4 can be independently determined regardless of the number of valves 18. Therefore, in order for the jet flow ejected from the auxiliary combustion chamber 2 to the main combustion chamber 1 to be uniformly dispersed in the main combustion chamber 1, the formation position of the communication hole 4 is determined. At that time, when the valve 18 is arranged at a position where it interferes with the jet flow ejected from the auxiliary combustion chamber 2, the groove 19 may be formed on the lower surface of the valve umbrella of the valve 18. The sizes of the grooves 9 and 19 may be determined according to the diameter of the jet flow from the communication hole 4, and the depth of the grooves 9 and 19 may be formed according to the trajectory of the jet flow. For example, the depth of the grooves 9 and 19 becomes deeper for the valve 18 arranged at a position closer to the ridge 30 of the pent roof type, and the depth of the groove 18 becomes deeper for the valve 18 positioned in the direction perpendicular to the ridge 30. The depth becomes shallow.

Further, since the intake / exhaust valve 18 forms a surface which is exposed to a high temperature jet from the auxiliary combustion chamber 2, low density and high strength ceramics such as Si ₃ N _{4 having} high heat resistance, or It is preferably made of a material such as a Ni or Cr heat resistant alloy. Similarly, the lower surface of the cylinder head 5 forms a surface exposed to a high-temperature jet from the auxiliary combustion chamber 2, so that the headliner 20 has a low density and high strength Si ₃ N ₄ rich in heat resistance. Ceramics, etc., or N
It is preferably made of a material such as i, Cr-based heat-resistant alloy.

Since this subchamber engine is constructed as described above, it operates as follows. That is, in the compression stroke, the auxiliary combustion chamber 2 passes from the main combustion chamber 1 through the communication hole 4.
The air introduced into the sub-combustion chamber 2 is swirl S in the direction opposite to the intake swirl IS in the main combustion chamber 1 due to the effect of the communication hole 4 which is offset from the central axis of the sub-combustion chamber and inclined.
Occurs. Fuel injection nozzle 1 for this swirl S
0 is injected from the multiple injection holes 7, the fuel spray rides on the swirl S, mixing is promoted and ignited, and the fuel is burned with rich fuel to N
The occurrence of O _X is suppressed. Combustion in the sub-combustion chamber 2 progresses to increase the pressure, transitions to an explosion / expansion stroke, and flames, unburned air-fuel mixture, and other gases are ejected from the sub-combustion chamber 2 through the communication holes 4 to the main combustion chamber 1. It Therefore, the jet flow from the sub-combustion chamber 2 has a vector in the radial direction of the main combustion chamber 1 in the same direction as the intake swirl IS remaining in the main combustion chamber 1 due to the effect of the inclined angle of the communication hole 4. It jets out, and is guided by the groove 9 of the head lower surface portion 21 and the groove 19 of the valve 18 and arrives in a state of being uniformly distributed to the periphery of the cylinder in a short period of time, where it is uniformly dispersed in the main combustion chamber 1 and new. Mixing with the air is achieved in a short period of time, and because the grooves 9 and 19 are evenly distributed, adjacent flames do not overlap with each other, the combustion speed is shortened, combustion is completed, and carbon,
It is possible to suppress generation of particulates such as smoke and HC, improve thermal efficiency, and improve performance.

FIG. 4 shows another embodiment of the subchamber engine according to the present invention. This embodiment has the same structure and function as the above-mentioned embodiment except that the groove 19S formed in the lower surface of the valve extends straight, and therefore, the same reference numerals are given and redundant description will be omitted.

Further, in this sub-chamber engine, the communication hole 4
A groove 1 forming a passage for a jet flow from the communication hole 4 in the valve lower surface portion and the cylinder head lower surface portion 12 located on the extension line of
9 and 9 are formed, an air-fuel mixture is generated in the auxiliary combustion chamber 2, and the auxiliary combustion chamber 2 is connected to the main combustion chamber 1 through the communication hole 4.
In order to make the most of the jet flow ejected to the sub-combustion chamber 2, it is preferable that the size of the sub-combustion chamber 2 be optimized in the ratio D / H between the diameter D in the direction perpendicular to the cylinder axis direction and the height H in the cylinder axis direction. . In this sub-chamber engine, it is preferable that the ratio D / H of the diameter D in the direction perpendicular to the cylinder axis direction and the height H in the cylinder axis direction is set to 1.6 to 2.2. When the ratio D / H of the diameter D of the auxiliary combustion chamber 2 in the direction perpendicular to the cylinder axis direction and the height H in the cylinder axis direction is set to the above set value, the mixture of fuel and air is swirled and the kinetic energy of fuel injection is set. It is possible to ensure the penetration of the spray from the auxiliary combustion chamber 2 to the main combustion chamber 1 without lowering the suction efficiency.

That is, this sub-chamber engine has a sub-combustion chamber 2
In order to generate the air-fuel mixture, the fuel is injected into the swirl S formed in the auxiliary combustion chamber 2 from the multiple injection holes 7 of the fuel injection nozzle 10 arranged in the center of the auxiliary combustion chamber. When the kinetic energy of the fuel spray is used for mixing, an appropriate distance between the wall surface of the auxiliary combustion chamber 2 and the multiple injection holes 7 is required to effectively use the penetration of the spray. It is necessary that the diameter D of the auxiliary combustion chamber 2 be large enough to ensure the penetration of the spray. On the other hand, considering the swirl ratio formed in the auxiliary combustion chamber 2,
If the diameter D of the sub-combustion chamber 2 is small and the swirl ratio is the same, the kinetic energy of the air in the sub-combustion chamber 2 becomes small, and the mixing energy of air and fuel becomes too small. On the other hand, when the diameter D of the auxiliary combustion chamber 2 is increased, the intake / exhaust valve 18 and the intake / exhaust port 1
The size of 7, 29 is reduced, and the suction efficiency and the exhaust efficiency are reduced. Considering the above two phenomena, the auxiliary combustion chamber 2
If the ratio D / H between the diameter D and the height H of the
It is effective to select / H within the range of about 1.6 to 2.2.

[0028]

The subchamber engine according to the present invention is constructed as described above and has the following effects. This sub-chamber engine communicates the main combustion chamber with the sub-combustion chamber on the cylinder center axis through a plurality of communication holes, sprays fuel from a fuel injection nozzle arranged in the center of the sub-combustion chamber, and A plurality of holes are formed at equal intervals in the circumferential direction eccentric from the center of the sub-combustion chamber, and the jet flow ejected from the sub-combustion chamber to the main combustion chamber with respect to the cylinder axis forms the communication hole in the main combustion. Since the swirl of the chamber is inclined in the direction of the normal flow, and in particular, the valve lower surface portion and the cylinder head lower surface portion located on the extension line of the communication hole are formed with the groove forming the passage for the jet flow, The jet flow is jetted in the same direction as the intake swirl remaining in the main combustion chamber with the radial vector of the main combustion chamber due to the effect of the inclined angle of the communication hole. Moreover, the jet flow is guided along the grooves formed on the lower surface of the cylinder head and the lower surface of the valve, and arrives in a state of being uniformly distributed around the cylinder in a short period of time. Therefore, it is evenly dispersed in the main combustion chamber to achieve mixing with fresh air in a short period of time, and since the grooves are evenly distributed, adjacent flames do not overlap with each other and combustion speed is shortened. Then, the combustion is completed, the generation of particulates such as carbon, smoke and HC is suppressed, the thermal efficiency is improved, and the performance can be improved.

Further, in this sub-chamber engine, since the valve is made of a material having a low density and a high strength such as ceramics, the valve and the lower surface of the head are not affected even if they come into contact with a hot jet. The durability can be improved without melting.

[0030] Therefore, in this pre-combustion chamber engine, the ignition combustion in the auxiliary combustion chamber is satisfactorily performed, the generation of the NO _X is burned in the fuel-rich can be suppressed. Further, since the ejection energy from the auxiliary combustion chamber to the main combustion chamber can be effectively utilized by the effect of the groove, and a large ejection energy can be given from the auxiliary combustion chamber to the main combustion chamber, Of the gas, such as flame and unburned air-fuel mixture, can be increased to promote mixing with fresh air in the main combustion chamber.

Further, since the auxiliary combustion chamber is located in the center of the cylinder, the distance that the jet flow reaches from the communication hole in the main combustion chamber is short, the combustion time is shortened, and the performance is improved.
Further, since the distance that the jet flow reaches from the sub-combustion chamber is short, the passage area of the communication hole can be formed large, the squeezing loss can be reduced, and the efficiency can be improved. Further, the passage area between the main combustion chamber and the auxiliary combustion chamber can be made large as a whole by the total of a large number of the communication holes formed on the outer periphery of the auxiliary combustion chamber, and the squeezing loss can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a sub-chamber engine according to the present invention.

FIG. 2 is an explanatory view showing an embodiment of a relationship between a communication hole and a groove of the sub-chamber engine of FIG.

3 is a perspective view showing an embodiment of a valve of the sub-chamber engine of FIG. 1. FIG.

FIG. 4 is an explanatory view showing another example of the relationship between the communication hole and the groove of the sub-chamber engine in FIG.

[Explanation of symbols]

 1 Main Combustion Chamber 2 Sub Combustion Chamber 3 Cylinder 4 Communication Hole 5 Cylinder Head 7 Multiple Injection Holes 9, 19, 19S Groove 10 Fuel Injection Nozzle 12 Pentroof Cylinder Head Lower Surface 15 Sub Chamber Member 18 Intake / Exhaust Valve 20 Headliner 21 Head Lower surface (lower surface of cylinder head) 28 Lower surface of sub chamber member

Claims (2)

[Claims] 1. A main combustion chamber formed on the cylinder side, a sub combustion chamber arranged on a cylinder head on the cylinder center axis,
In a sub-chamber engine having a plurality of communication holes communicating the main combustion chamber and the sub-combustion chamber and a fuel injection nozzle having an injection hole opened in the center thereof for spraying fuel into the sub-combustion chamber, the communication hole is A plurality of jets, which are formed at equal intervals in the circumferential direction eccentric from the center of the sub-combustion chamber and are jetted from the sub-combustion chamber to the main combustion chamber with respect to the cylinder axis, flow forward to the swirl of the main combustion chamber. And a groove that forms a passage for a jet flow from the communication hole is formed in the valve lower surface portion and the cylinder head lower surface portion that are formed so as to be inclined in the same direction. Subchamber engine. 2. The subchamber engine according to claim 1, wherein the valve is made of a material such as low density and high strength ceramics.