JP2826796B2 - Secondary combustion chamber diesel engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sub-combustion chamber type diesel engine, and more particularly to an engine capable of effectively mixing air in a main combustion chamber with combustion expansion gas.

[0002]

2. Description of the Related Art The general structure of an auxiliary combustion chamber type diesel engine is as follows. That is, the sub combustion chamber is provided in the cylinder head, and the main combustion chamber is provided in the cylinder.
An injection port is provided in the cylinder head at a position eccentric from the cylinder center axis, and the injection port is directed toward the cylinder center. As this type of engine, there is an engine in which intake swirl is generated along an inner peripheral surface of a cylinder in a main combustion chamber.

[0003]

In the above-mentioned intake swirl type engine, it is expected that the air in the main combustion chamber and the combustion expansion gas injected from the injection port are effectively mixed by the intake swirl, so that the combustion performance is improved. Was done. But,
In reality, combustion performance is not significantly improved compared to engines without intake swirl. It is considered that the reason is that the air in the main combustion chamber and the combustion expansion gas are not effectively mixed.

An object of the present invention is to effectively mix air swirled by intake swirl and combustion expansion gas in a sub-combustion chamber type diesel engine.

[0005]

The present invention deflects a part of the combustion expansion gas toward the front of a specific swirling gas flow, as will be described later. However, there has been no room for the idea as in the present invention since it has not been confirmed what flow state is exhibited in the main combustion chamber.

The method of confirming the flow state of the combustion expansion gas in the main combustion chamber performed by the inventors of the present invention is as follows. Vaseline mixed with molybdenum disulfide powder was thinly applied to the piston top surface, and the engine was motored. With this configuration, when the piston is raised, the vaseline is melted by the compression heat generated in the main combustion chamber. Then, when the piston descends from the top dead center, air is ejected from the injection port into the main combustion chamber due to a pressure difference generated between the sub-combustion chamber and the main combustion chamber, and this air flows along the piston top surface. Vaseline flows with the flow of the air, and the molybdenum disulfide powder is aligned along the flow trajectory.

For this reason, after motoring for a predetermined time,
By taking out the piston and visually observing the orientation of the molybdenum disulfide powder, the flow state of air in the main combustion chamber could be confirmed. As a result, the present inventors, when viewed in a direction parallel to the cylinder center axis, the air flows straight forward along the injection axis of the injection port, and is located on both sides of the injection axis, and the turning direction is It was confirmed that a pair of swirling flows opposite to each other were formed. And based on this knowledge, the inventors, when actually driving the engine,
It was presumed that the combustion expansion gas ejected from the injection port showed the same flow state as the air in the main combustion chamber.

Next, based on this estimation, the inventors actually operated the engine for a predetermined time, took out the piston, and observed finely the carbon adhering to the piston top surface. It was confirmed that they were attached in almost the same orientation, and the validity of the above presumption was confirmed. Furthermore, in the same individual engine, even if the engine rotation speed is different or the fuel injection amount to the sub-combustion chamber is different, the position of each swirl center of the pair of swirl gas flows is substantially constant. I also checked.

Further, the inventors have obtained the above-mentioned confirmation method by
About the conventional intake swirl type engine, the flow state of the combustion expansion gas was confirmed. As a result, as shown in FIG. 6, the swirling gas flow 1 in the same swirling direction as the intake swirl 145.
06, the turning radius of the swirling gas flow 107 in the reverse turning direction became smaller. This is considered to be because the swirling gas flow 106 is accelerated by the acceleration by the intake swirl 145, and the swirling gas flow 107 is suppressed by the collision by the intake swirl 145. Then, the inventors confirmed that a large gas non-attainment region 148 was formed in front of the swirling gas flow 107, and identified factors that did not improve the mixing performance of combustion expansion gas and air in the main combustion chamber. . In the drawings, reference numeral 104 denotes a nozzle, 140 denotes a gas passage groove, and 141 denotes a gas passage groove 140.
At the beginning.

[0010] In response to this result, the present inventors deflect a part of the combustion expanding gas forward of the swirl gas flow 107 in the reverse swirl direction with respect to the intake swirl 145, and this swirl gas flow 10
It is thought that the gas non-attainment area 148 in front of No. 7 decreases or disappears, and thus the present invention has been reached.

[0011]

[Means for Solving the Problems]

(First Invention) In the first invention, as shown in FIG. 1, a sub-combustion chamber 1 is provided in a cylinder head 23, and a main combustion chamber 5 is provided in a cylinder 22. Then, at a position eccentric from the cylinder center axis 3, an injection port 4 is provided in the cylinder head 23,
By directing the nozzle 4 toward the center of the cylinder 22, the combustion expansion gas injected from the nozzle 4 is directed straight forward along the injection axis 12 of the nozzle 4 when viewed in a direction parallel to the cylinder center axis 3. The gas flow 27 and the injection axis 1
2 and a pair of swirling gas flows 6, 7 whose swirling directions are opposite to each other. And, in the main combustion chamber 5, the intake swirl 45 along the inner peripheral surface of the cylinder 22 is provided.
Was configured to occur.

Further, when viewed in a direction parallel to the cylinder center axis 3, at least one of the central portions of the cylinder head surface 9 and the piston top surface 8 facing the main combustion chamber 5 has a raised gas deflecting portion 46. And a gas deflecting guide surface 47 is formed on the rising surface of the gas deflecting section 46. Characterized by being directed forward.

(Second Invention) In a second invention, as shown in FIG. 1, in the first invention, a gas passage groove 40 is formed in the piston top surface 8 so as to be viewed in a direction parallel to the cylinder center axis 3. The starting end 41 of the gas passage groove 40 is formed at a position overlapping with the injection port 4, and the injection axis 1 of the injection port 4 is formed from the starting end 41.
The gas passage groove 40 was led out forward along 2.

A cylinder head surface 9 overlapping the gas passage groove 40 when viewed in a direction parallel to the cylinder center axis 3;
A gas deflecting portion 46 is provided on at least one of the inner bottom surfaces of the gas passage grooves 40.

(Third Invention) In a third invention, as exemplified in FIG. 1, in either the first invention or the second invention, a cylinder head surface 9 and a piston top surface facing the main combustion chamber 5 are provided. 8, at least one of the valve recesses 10 and 11 is recessed in at least one of the cylinder center axes 3.
This pair of valve recesses 10.1
1 was distributed on both sides of the injection axis 12 of the nozzle 4.

When viewed in a direction parallel to the cylinder center axis 3, the respective swirl centers 14 and 15 of the pair of swirl gas flows 6 and 7 are located in the pair of valve recesses 10 and 11 respectively. Features.

(Fourth Invention) In a fourth invention, as shown in FIG. 1, in any one of the first invention to the third invention, a total of three intake valves 32 and 33 and three exhaust valves 35 are provided. It is characterized by having.

(Fifth Invention) According to a sixth invention, as shown in FIG. 4, in any one of the first invention to the fourth invention, an intake port 28 is provided in the cylinder head 23, and the intake port 28 An intermediate intake valve port 30 and a terminal intake valve port 31 were provided at the intermediate portion and the terminal portion.

Assuming an imaginary transverse line 56 orthogonal to the cylinder center axis 3 in the radial direction of the cylinder 22, when viewed in a direction parallel to the cylinder center axis 3, areas on both sides of the virtual transverse line 56 54/57, one area 5
7, the intake port 28 was located.

An intake port portion 58 at the start end of the intake port 28 is formed in parallel with the imaginary traversing line 56, and the imaginary traversing line 56 is terminated with respect to the center point 59 of the intermediate intake valve port 30. By arranging the center point 60 of the intake valve port 31 close to each other, the center point passing line 61 passing through both the center points 59 and 60 is aligned with the axis 6 of the intake introduction port portion 58.
Tilt to 2.

Further, by forming the inter-port opening port portion 63 located between the center points 59 and 60 in parallel with the center point passing line 61, the inter-port opening port portion 63 is formed.
Is inclined with respect to the direction of the intake introduction port portion 58.

(Sixth Invention) According to a sixth invention, as shown in FIG. 4, in the fifth invention, the port portion 63 between the valve ports is provided.
In the peripheral wall 64, an outward portion 65 on a side far from the imaginary transverse line 56 when viewed in a direction parallel to the cylinder center axis 3 is curved so as to bulge outward.

(Seventh invention) According to a seventh invention, as illustrated in FIG. 4, in any one of the fifth invention and the sixth invention, the intake port portion 58 is moved from the start end to the end. The diameter is reduced.

[0024]

Actions and effects of the present invention

(First Invention) As exemplified in FIG. 1 (A), a part of the combustion expansion gas is deflected forward of the swirling gas flow 7 in the reverse swirling direction with respect to the intake swirl 45 by the guide of the gas guide deflection surface 47. ,
The gas non-attainment area 48 in front of the swirling gas flow 7 is reduced or disappears. Therefore, the mixing performance of the combustion expansion gas and air in the main combustion chamber 5 is improved, and the output performance is improved.

(Second Invention) As illustrated in FIG. 1A, the combustion expansion gas ejected from the injection port 4 is
Since it passes through the inside with low resistance, its flow velocity increases. Therefore, the mixing performance of the combustion expansion gas and the air in the main combustion chamber 5 is improved, and the output performance is further improved.

(Third Invention) As illustrated in FIG. 1A, the air in the pair of valve recesses 10 and 11 is surrounded by the swirling gas flows 6 and 7 from the surroundings, and is dragged by the swirling gas flows 6 and 7. It turns as arrows 18 and 19 in the same direction as the flows 6 and 7. In this case, the specific gravity of the air is the swirling gas flow 6.
7, the air is diffused into the swirling gas flows 6.7 as indicated by arrows 20 and 21 due to the difference in centrifugal force, so that these are effectively mixed and the air in the main combustion chamber 5 is Usage rate increases. Therefore, the mixing performance of the combustion expansion gas and the air in the main combustion chamber 5 is improved, and the output performance is further improved.

(Fifth Invention) As illustrated in FIG. 4, the intake air 67 going to pass through the inter-port port portion 63 will proceed straight by inertia force while being directed at the intake introduction port portion 58. However, this port portion between the valve openings 6
Since the direction of 3 is inclined with respect to the direction of the intake introduction port portion 58, the intake 67 is guided to the terminal port portion 68 by the outer portion 65 of the peripheral wall 64 of the inter-valve port portion 63, and its arc shape is formed. Is drawn into the cylinder 22 from the terminal intake valve port 31 while wrapping around the wall of the cylinder.

For this reason, the intake air 67 sucked into the cylinder 22 from the terminal intake valve port 31 is directed along the inner peripheral surface of the cylinder 22, and the turbulent flow near the terminal intake valve port 31 which becomes the intake resistance. Is prevented, a high-speed intake swirl 45 is generated in the main combustion chamber 5, the mixing performance of the combustion chamber expansion gas and air in the main combustion chamber 5 is improved, and the output performance is further improved.

(Sixth Invention) As exemplified in FIG. 4, the intake air 67 guided by the outward portion 65 is smoothly guided by its curvature, so that the guide resistance of the intake air 67 can be reduced, and this outward The speed of the intake swirl 45 is further increased as compared with the case where the portion 65 is formed straight.

(Eighth Invention) As exemplified in FIG. 4, the flow velocity of the intake air flowing from the intake port introduction part 58 to the valve port part 63 is increased, and the flow velocity of the intake air sucked into the cylinder 22 is increased. As a result, the speed of the intake swirl 45 in the cylinder 22 is further increased.

[0031]

An embodiment of the present invention will be described with reference to the drawings.
First, a first embodiment will be described with reference to FIGS.
The first embodiment is a vertical multi-cylinder diesel engine provided with a sub-chamber type combustion chamber, and its structure is as follows. That is, as shown in FIG. 1B, a cylinder head 23 is mounted on the upper side of the cylinder 22, a piston 24 is fitted in the cylinder 22, and the main combustion chamber 5 is provided in the cylinder 22.
Are formed. A substantially spherical swirl-type sub-combustion chamber 1 facing the fuel injection nozzle 2 is formed in the cylinder head 23, and the sub-combustion chamber 1 is connected to the main combustion chamber 5 through an injection port 4.
Is communicated to.

As shown in FIG. 1A, the injection port 4 is provided near the inner peripheral surface of the cylinder 22, that is, at a position eccentric from the cylinder center 3. As shown in FIG. 2, the nozzle 4 is composed of a main nozzle 25 and a pair of left and right side nozzles 26 along both left and right sides thereof.

The main injection port 25 is formed in an obliquely cylindrical shape, and its axis 25a is inclined at an angle of elevation of approximately 45 ° with the cylinder head surface 9 facing the main combustion chamber 5 as a reference plane. Is aimed at. This axis 2
5a may be directed to the center of the cylinder 22,
It may be shifted to some extent from the cylinder center axis 3.

The side injection ports 26, 26 are formed in the shape of a truncated cone expanding downward, and their axes 26a, 26a are shown in FIG.
As seen from the side, the axis 25a of the main injection port 25 is viewed from the side.
As in the case of FIG.
As seen from the front, the lower side is inclined so as to spread outward. The elevation angle of the axis 25a of the main injection port 25 and the elevation angle of the axis 26a of the side injection port 26 are not particularly limited, but are preferably about 40 ° to 50 °.

In such a sub-chamber type combustion chamber, the sub-combustion chamber 1
The combustion expansion gas ejected from the nozzle via the injection port 4 flows in the main combustion chamber 5 as follows. That is, as shown in FIG. 1A, when viewed in a direction parallel to the cylinder center axis 3,
The combustion expansion gas ejected from the injection port 4 is located on both sides of the injection gas axis 27 of the injection port 4 and a straight gas flow 27 heading forward along the injection axis 12 of the injection port 4 and has a pair of swirling directions opposite to each other. The swirling gas flows 6 and 7 are formed. The injection axis 12 of the nozzle 4 is on an extension of the axis 25 a of the main nozzle 25.

The positions where the respective swirling centers 14 and 15 of the pair of swirling gas flows 6 and 7 are generated are as follows. That is, assuming a virtual transverse line 13 perpendicular to the injection axis 12 of the injection port 4 in the radial direction of the cylinder 22, each of the turning centers 14.
15 occurs. In the case where the injection port 4 includes only the main injection port 25, the turning radii of the pair of swirling gas flows 6 and 7 are small, but the turning centers 14 and 15 are generated at substantially the same positions as in this embodiment.

Further, an intake swirl 45 is generated along the cylinder 22 in the main combustion chamber 5. Means for forming the intake swirl 45 will be described later. This intake swirl 45
Turns in the counterclockwise direction, the turning radius of the turning gas flow 6 turning in the counterclockwise direction increases, and the turning radius of the turning gas flow 7 turning in the clockwise direction decreases.

In this embodiment, the following configuration is employed to effectively mix the air swirled by the intake swirl 45 and the combustion expansion gas. That is, a raised gas deflecting portion 46 is provided at the center of the piston top surface 8,
The gas deflection guide surface 4 is provided on the rising surface of the gas deflection section 46.
The gas deflecting guide surface 47 is curved with a gentle inclination from the central portion of the main combustion chamber 5 toward the front of the swirling gas flow 7 in the reverse swirling direction with respect to the intake swirl 45. The tangential inclination angle of the gas deflection guide surface 47 is
It is desirable that the angle be within 45 ° with respect to the injection axis 12. The gas deflecting portion 46 may be formed at the center of the cylinder head surface 9 facing the main combustion chamber 5, or may be formed at both the piston top surface 8 and the cylinder head surface 9.

According to this structure, a part of the combustion expansion gas is guided by the gas deflecting guide surface 47 so that the intake swirl 4
5 is deflected to the front of the swirling gas flow 7 in the reverse swirling direction, and the gas non-reachable area 48 in front of the swirling gas flow 7 decreases or disappears.

In this embodiment, a gas passage groove 40 is formed in the piston top surface 8 in order to increase the flow velocity of the combustion expansion gas. The structure of the gas guide groove 40 is as follows. That is, when viewed in a direction parallel to the cylinder center axis 3, the starting end 41 of the gas passage groove 40 is formed at a position overlapping with the injection port 4, and the injection axis 1 of the injection port 4 is formed from the starting end 41.
A gas passage groove 40 is extended forward along 2. The gas guide groove 40 is formed such that its width gradually increases and its depth gradually decreases as the gas guide groove 40 moves away from the injection port 4 along the injection axis 12 of the injection port 4 from its start end 41.

The left and right portions of the gas passage groove 40 are formed by the injection axis 12 of the pair of left and right valve recesses 10 and 11.
The end central portion of the gas passage groove 40 overlaps with the portions 42 and 43 closer to the imaginary transverse line 13 in the front valve recess 37. The gas deflecting section 46 is provided on the inner bottom surface of the gas passage groove 40. The gas deflecting portion 46 is raised to the same height as the piston top surface 8. When the gas guide deflection unit 46 is provided on the cylinder head surface 9,
The gas passage groove 40 when viewed in a direction parallel to the cylinder center axis 3.
And at least the combustion expansion gas is
The gas guide deflecting portion 46 is made to enter the gas passage groove 40 at the time of jetting out of the gas. According to such a configuration, the combustion expansion gas spouted from the spout 4 is supplied to the gas passage groove 40.
Therefore, the flow rate of the combustion expansion gas increases.

As shown in FIGS. 1B and 1C,
In the cylinder head 23, an intake port 28 and an exhaust port 29 are formed.
The intake valves 32 and 33 are provided at the 0-terminal intake valve port 31 so as to be openable and closable, and the exhaust valve 35 is provided at the exhaust valve port 34 of the exhaust port 29 so as to be openable and closable. This is a so-called three-valve structure. These intake / exhaust valves 32, 33, 35 are opened and closed at a predetermined timing via a valve train including a push rod 36 and the like. And these intake and exhaust valves 32
As shown in FIG. 1 (A), a pair of left and right valve recesses 10.
11 and the front valve recess 37 are recessed. The center of each recess 16 of this pair of valve recesses 10 and 11
17 is set at an essentially equal distance from the nozzle 4.

In order to effectively mix the air in the pair of valve recesses 10 and 11 with the pair of swirling gas flows 6.7, as shown in FIG. Looking in the direction, a pair of valve recesses 10 and 11
A pair of swirling gas flows 6.7 at the recess centers 16
Of the turning centers 14 and 15 are coincident with or close to each other.

According to such a configuration, the air in the pair of valve recesses 10 and 11 is surrounded by the swirling gas flows 6 and 7 from the surroundings, and is dragged by the swirling gas flows 6 and 7 in the same direction as the spiral windings 6 and 7. It turns like 18.19. in this case,
Since the specific gravity of the air is larger than that of the combustion expansion gas, the air is diffused into the swirling gas flows 6.7 as indicated by arrows 20 and 21 due to the difference in centrifugal force, and the mixing is effectively performed.

Further, as shown in FIG. 1A, the front valve recess 37 is set on the injection axis 12 of the injection port 4 when viewed in a direction parallel to the cylinder center axis 3. Therefore, the air in the front valve recess 37 and the straight gas flow 27
Is effectively mixed. The recess center 38 of the valve recess 37 is set near the injection axis 12 of the injection port 4. It is desirable that the position of the recess center 38 be substantially coincident with the injection axis 12.

Next, the structure of the cylinder head of the first embodiment will be described in detail. As shown in FIG. 4A, assuming a second imaginary transverse line 56 orthogonal to the cylinder center axis 3 and the crank axis 70 in the radial direction of the cylinder 22, as viewed in a direction parallel to the cylinder center axis 13. This second
The intake port 28 is located in the rear area 57 of the front area 54 and the rear area 57 located on both sides of the virtual transverse line 56. The intake port 28 is connected to the cylinder head 23
Is formed from the right wall 53 to the left. The intake port portion 58 at the start end of the intake port 28 is formed parallel to the second imaginary transverse line 56. The intake port portion 58 may be essentially parallel to the second virtual transverse line 56. An intermediate intake valve port 30 and a terminal intake valve port 31 are provided at an intermediate portion and a terminal portion of the intake port 28,
These are arranged on the left and right sides of the crank axis 70.

Then, the center point 60 of the end intake valve port 31 is more than the center point 59 of the intermediate intake valve port 30 in the second virtual transverse line 5.
6 and the center points 59.6
A center point passing line 61 passing through 0 is inclined with respect to an axis 62 of the intake introduction port portion 58. And both center points 5
The inter-port port portion 63 located between 9 and 60 is formed parallel to the center point passing line 61, so that the orientation of the inter-port port portion 63 is oriented with respect to the orientation of the intake introduction port portion 58. Is tilted. The port portion 63 between the valve ports is
What is necessary is just to be essentially parallel to the center point passing line 61. In the drawing, the symbol θ is the inclination angle of the center point passing line 61 with respect to the axis 62 of the intake introduction port portion 58.

According to such a configuration, the intake air 67 which is going to pass through the port portion 63 between the valve openings tries to proceed straight by inertia force while being directed at the intake port portion 58. Since the direction of the valve opening port portion 63 is inclined with respect to the direction of the intake introduction port portion 58, the intake 67 is formed on the peripheral wall 64 of the valve opening port portion 63.
Is guided to the terminal port portion 68 by the outer side portion 65 of the cylinder, and is drawn into the cylinder 22 from the terminal intake valve port 31 while wrapping around the arc-shaped wall. For this reason,
The intake air 67 sucked into the cylinder 22 from the terminal intake valve port 31 is directed along the inner peripheral surface of the cylinder 22 to prevent the occurrence of turbulence near the terminal intake valve port 31 which becomes intake resistance. The speed of the intake swirl 45 increases.

When viewed in a direction parallel to the cylinder center axis 3, an outer portion 65 of the peripheral wall 64 of the port portion 63 between the valve ports, which is farther from the second imaginary transverse line 56, protrudes outward. It is curved in a shape. For this reason, the intake 67 guided by the outer side portion 65 is smoothly guided by its curvature, so that the guide resistance of the intake 67 can be reduced,
Compared to a case where the outer portion 65 is formed straight,
The speed of the intake swirl 45 is further increased.

Further, the diameter of the intake port portion 58 is reduced from the start end to the end. For this reason, the flow velocity of the intake air flowing from the intake port introduction part 58 to the valve port part 63 is increased, the flow velocity of the intake air sucked into the cylinder 22 is increased, and the velocity of the intake swirl 45 is further increased.

The exhaust port 29 is connected to the second virtual transverse line 5.
In the region 54 on the front side of 6, it is formed from the crank axis 70 to the left. An exhaust valve port 34 is provided at the start end of the exhaust port 29. The sub-combustion chamber 1 is disposed on the right side of the crankshaft line 70 behind the second virtual transverse line 56. The push rod chamber 71 is disposed on the second transverse line 56 to the left of the crank axis 70.
Reference numeral 72 in the drawing denotes a head bolt insertion hole, which is arranged at a position surrounding the cylinder 22 at intervals of 60 ° in a total of six.

The second embodiment shown in FIG. 5 is a modification of the first embodiment shown in FIG. 1, in which a pair of left and right valve recesses 10 and 11 are formed on a cylinder head surface 9 facing the main combustion chamber 5.
The valve recesses 10 and 11 are formed concentrically with the exhaust valve port 34 and the intermediate intake valve port 30. The pair of left and right valve recesses 10 and 11 is provided not only for one of the cylinder head surface 9 and the piston top surface 8 facing the main combustion chamber 5,
They may be formed on both sides. The structure of the other elements of the second embodiment is the same as that of the first embodiment.

Although the contents of each embodiment of the present invention are as described above, the present invention is not limited to the above embodiments. For example, the type of engine is not limited to vertical, horizontal,
It may be an inclined type. The sub-combustion chamber 1 is not limited to the swirl chamber, but may be a pre-combustion chamber.

Further, the recess centers 16 and 17 of the pair of valve recesses 10 and 11 are not limited to the positions deviated from the imaginary traversing line 13 to the injection port 4 side. It may be arranged at a position deviated to the side opposite to the injection port 4. In this case, a pair of valve recesses 10 and 11
Recess centers 16 and 17 and a pair of swirling gas flows 6.7
It is necessary to reduce the elevation angle of the injection port 4 so that the respective swirl centers 14 and 15 essentially coincide with or approach each other so that the generation position of the swirling gas flows 6 and 7 is separated from the injection port 4. .

However, it is desirable that the recess centers 16 and 17 of the valve recesses 10 and 11 are arranged at positions deviated from the imaginary transverse line 13 toward the injection port 4 as in the above embodiments. This is because, as the positions of the valve recesses 10 and 11 and the swirling gas flows 6 and 7 are closer to the injection port 4, the swirling gas flow comes into contact with the air in the valve recesses 10 and 11 at a higher flow rate, and the mixing thereof is more effectively performed. .

The turning centers 14 and 15 of the pair of swirling gas flows 6 and 7 may be positioned in the pair of valve recesses 10 and 11 when viewed in a direction parallel to the cylinder center axis 3. However, the effectiveness of mixing the air in the pair of valve recesses 10 and 11 with the pair of swirling gas flows 6.7 tends to increase as the swirling centers 14 and 15 approach the recess centers 16 and 17, Each turning center 1 is located in an area surrounded by an imaginary circle having a radius of 2/3 of a radius of each of the valve recesses 10 and 11 around each of the recess centers 16 and 17.
It is desirable to locate 4.15.

Further, the center of each of the recesses 16 and 17 is set at one half or one half of the radius of each of the valve recesses 10 and 11.
It is more desirable to position each of the turning centers 14 and 15 in a region surrounded by a virtual circle having a radius of ４ or １ ／. Also, each turning center 14/15 is located at the valve recess 10/15.
The distances from the nozzle hole 4 to the respective recess centers 16 and 17 do not necessarily have to be equal as long as they are located within the area 11 or the area surrounded by the virtual circle.

Further, in each embodiment of the present invention, the swirling centers 14 and 7 of the pair of swirling gas flows 6 and 7 generated by the combustion and expansion gas spouted from the injection port 4 flowing naturally along the piston top surface 8. 15 is located in the pair of valve recesses 10 and 11, and does not have a structure in which the flow of the combustion expansion gas is forcibly deflected toward the pair of valve recesses by a gas guide groove or the like. When the combustion expansion gas is forcibly deflected by the gas guide groove or the like, most of the gas overflows from the gas guide groove before reaching the pair of valve recesses, and only a small amount of the combustion expansion gas is introduced into the pair of valve recesses. .

The gas passage groove 40 described in the above embodiment is used.
Is merely used to reduce the throttle resistance between the cylinder head surface 9 facing the main combustion chamber 5 and the piston top surface 8, and directs the combustion expansion gas toward the pair of valve recesses 10 and 11. It is not intended to force deflection. According to the confirmation by the present inventors, the position of each of the swirl centers 14 and 15 of the pair of swirl gas flows 6 and 7 is
Essentially at the same position, with or without zeros. From this, it is understood that the combustion expansion gas is not forcibly deflected toward the pair of valve recesses 10 and 11 by the gas passage groove 40.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a first embodiment of the present invention.
(A) is a plan view of the piston fitted inside the cylinder, FIG.
1B is a cross-sectional view taken along line BB of FIG. 1A, FIG. 1C is a cross-sectional view taken along line CC of FIG. 1A, and FIG. It is D sectional drawing.

FIG. 2 is a perspective view of a piston head used in the first embodiment of the present invention.

FIG. 3 is a schematic view of a nozzle used in the first embodiment of the present invention;
FIG. 3A is a perspective view of the nozzle viewed from the side, and FIG.
FIG. 3 is a perspective view of the nozzle as viewed from the front side.

4A and 4B are views for explaining a cylinder head used in the first embodiment of the present invention. FIG. 4A is a cross-sectional plan view, and FIG. 4B is a cross-sectional view taken along line BB of FIG. 4A. is there.

FIG. 5 is a longitudinal sectional view of a cylinder head used in a second embodiment of the present invention.

6 (A) and 6 (B) are views for explaining the prior art, in which FIG. 6 (A) is a plan view of a piston fitted inside a cylinder, and FIG.
FIG. 6A is a cross-sectional view taken along the line BB of FIG.
-It is a C line cross section.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Sub combustion chamber, 3 ... Cylinder center axis line, 4 ... Injection port, 5 ...
Main combustion chamber, 6 ・ 7 ・ ・ ・ A pair of swirling gas flows, 8 ・ ・ ・ Piston top surface, 9 ・ ・ ・ Cylinder head surface, 10 ・ 11 ・ ・ ・ A pair of left and right valve recesses, 12 ・ ・ ・ 4 injection axes, 14 ・ 15 ・ ・ ・ 6.7
Center of rotation, 22 ... cylinder, 23 ... cylinder head,
28 ... intake port, 30 ... middle intake valve port, 31 ... end intake valve port, 32/33 ... intake valve, 35 ... exhaust valve, 40 ... gas passage groove, 41 ... 40 start end, 45 ... intake swirl,
46: gas deflecting section, 47: gas deflecting guide surface, 54: (front side) area, 56: (second) virtual transverse line, 57: (rear side) area, 58: intake inlet port portion, 59 ... 30 , The central point of 60 ... 31, 61 ... the central point passing line, 62
... 58 axis lines, 63 ... port portion between valve openings, 64 ... peripheral wall of 63, 65 ... outboard portion.

Continuation of the front page (56) References JP-A-4-287828 (JP, A) JP-A-5-179952 (JP, A) JP-A-2-259228 (JP, A) JP-A-3-63718 (JP) , U) Hikaru 3-118231 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) F02B 1/00-23/10

Claims (7)

(57) [Claims] An auxiliary combustion chamber (1) is provided in a cylinder head (23), a main combustion chamber (5) is provided in a cylinder (22), and the cylinder head is positioned eccentrically from a cylinder center axis (3).
(23) is provided with a nozzle (4), and this nozzle (4) is
By pointing to the center of 2), the cylinder center axis
When viewed in a direction parallel to (3), the combustion expansion gas injected from the injection port (4) flows forward along the injection axis (12) of the injection port (4) and a straight gas flow (27). A pair of swirling gas flows (6) located on both sides of the axis (12) and having swirling directions opposite to each other.
A sub-combustion-chamber diesel engine configured to form (7) and configured to produce an intake swirl (45) along the inner peripheral surface of the cylinder (22) in the main combustion chamber (5). And the main combustion chamber when viewed in a direction parallel to the cylinder center axis (3).
(5) Cylinder head surface (9) facing inside and piston top surface (8)
At least one of the central portions has a raised gas deflecting portion (46), and a gas deflecting guide surface (47) is formed on the rising surface of the gas deflecting portion (46). 47) A sub-combustion chamber type diesel engine characterized in that 47) is directed from the central portion of the main combustion chamber (5) to the front of the swirling gas flow (7) in a direction opposite to the intake swirl (45). 2. The sub-combustion chamber diesel engine according to claim 1, wherein a gas passage groove is formed on a top surface of the piston.
(40) is recessed and viewed in a direction parallel to the cylinder center axis (3), and the starting end (41) of the gas passage groove (40) is connected to the nozzle (4).
From the starting end (41) and the spout (4)
A gas passage groove (40) is led forward along the injection axis (12) of the cylinder, and the gas passage groove is viewed in a direction parallel to the cylinder center axis (3).
Cylinder head surface (9) overlapping with (40) and gas passage groove
At least one of the inner bottom surfaces of (40) has a gas deflector (4
6. An auxiliary combustion chamber type diesel engine provided with 6). 3. The auxiliary combustion chamber type diesel engine according to claim 1, wherein
At least one pair of valve recesses (10) and (11) is recessed in at least one of the cylinder head surface (9) facing the inside of the main combustion chamber (5) and the piston top surface (8). ) And a pair of valve recesses
(10) and (11) are distributed on both sides of the injection axis (12) of the injection port (4), and viewed in a direction parallel to the cylinder center axis (3), the pair of valve recesses (10) and (11) are viewed. ), Wherein the respective swirling centers (14) and (15) of the pair of swirling gas flows (6) and (7) are respectively positioned. 4. The auxiliary combustion chamber type diesel engine according to any one of claims 1 to 3, further comprising a total of three intake valves (32) and (33) and three exhaust valves (35). And a sub-combustion chamber diesel engine. 5. An auxiliary combustion chamber type diesel engine according to claim 1, wherein an intake port (28) is provided in the cylinder head (23), and an intermediate portion of the intake port (28). The middle intake valve port (3
0) and a terminal intake valve port (31), and assuming a virtual transverse line (56) orthogonal to the cylinder center axis (3) in the radial direction of the cylinder (22), the cylinder center axis (3) When viewed in a parallel direction, one area (57) of the areas (54) and (57) on both sides of the virtual crossing line (56) includes:
The intake port (28) is located, and an intake introduction port portion at the start end of the intake port (28)
(58) is formed in parallel with the imaginary traversing line (56), and with respect to the imaginary traversing line (56), By arranging the center point (60) closer, both center points (59) and (60)
Through the center point passing line (61) passing through
(58) is inclined with respect to the axis (62), and the port portion (63) located between the two center points (59) and (60) is placed in parallel with the center point passing line (61). The auxiliary combustion chamber type diesel engine, wherein the direction of the port portion between valve openings (63) is inclined with respect to the direction of the intake port portion (58) by being formed. 6. The auxiliary combustion chamber type diesel engine according to claim 5, wherein, of the peripheral wall (64) of the port portion between valve openings (63), when viewed in a direction parallel to the cylinder center axis (3), The virtual crossing line
An auxiliary combustion chamber type diesel engine characterized in that an outward portion (65) farther from the (56) is curved outwardly. 7. The auxiliary combustion chamber type diesel engine according to claim 5, wherein the diameter of the intake introduction port portion (58) is reduced from the start end to the end. An auxiliary combustion chamber type diesel engine characterized by the above-mentioned.