JP6824801B2 - Sub-chamber structure of internal combustion engine - Google Patents

Description

The present invention relates to an auxiliary chamber structure of an internal combustion engine.

A sub-chamber internal combustion engine having a main combustion chamber and a combustion chamber partitioned into a sub-chamber is known. The sub-chamber internal combustion engine ignites the air-fuel mixture in the sub-chamber, and ignites the air-fuel mixture in the main combustion chamber by a torch-shaped flame ejected from the sub-chamber into the main combustion chamber through the communication hole. The auxiliary chamber is formed between the female screw hole and the partition member by attaching a bottomed tubular partition member having a male screw on the outer periphery to the female screw hole formed on the wall surface of the combustion chamber (for example, Patent Document). 1). By inserting the driving pin between the partition member and the female screw hole, the partition member is prevented from rotating with respect to the female screw hole, and the partition member is prevented from falling off.

Jikkenhei No. 5-83327

However, in the sub-chamber structure of Patent Document 1, since the rotational position and insertion depth of the partition wall member with respect to the female screw hole are fixed by the driving pin, no fastening force (axial force) is generated in the partition wall member. Therefore, if the driving pin falls off for some reason, the partition wall member can rotate with respect to the female screw hole, and the partition wall member may fall off from the female screw hole. Further, in the sub-chamber structure of Patent Document 1, since it is not assumed that the partition wall member is screwed into the female screw hole until a fastening force is generated on the partition wall member, that is, a tightening torque is applied to the partition wall member, a tightening torque is applied to the partition wall member. There is no structure in which the tool for addition engages.

In view of the above background, it is an object of the present invention to provide an auxiliary chamber structure of an internal combustion engine capable of suppressing the falling off of a partition wall member.

In order to solve the above problems, one aspect of the present invention is a combustion chamber wall surface (7) formed on the lower end surface of the cylinder head (3) and forming a main combustion chamber (12) in cooperation with the piston (11). A female screw hole (20) recessed in the wall surface of the combustion chamber and having a female screw (20A) on the inner peripheral surface and a male screw (23D) screwed with the female screw are provided on the outer peripheral surface, and the female screw hole is provided with the female screw hole. It has a partition member (23) that is screwed in from the main combustion chamber side and forms an auxiliary chamber (24) in cooperation with the female screw hole, and the partition member is provided on an outer surface exposed to the main combustion chamber side. Provided is an internal combustion engine sub-chamber structure characterized by having a formed tool engaging portion (26) and a plurality of communication holes (34) connecting the main combustion chamber and the sub-chamber.

According to this aspect, since the tool can be engaged with the tool engaging portion to apply a tightening torque to the partition wall member, a fastening force (axial force) is generated in the partition wall member to fasten the partition wall member to the female screw hole. be able to.

Further, in the above aspect, it is preferable that the tool engaging portion includes a plurality of recesses (27) recessed inward in the radial direction from the outer peripheral surface of the partition wall member, and the communication hole is opened in the recess. ..

According to this aspect, since the tool engaging portion and the communication hole are provided at the same position, the amount of protrusion of the partition wall member from the wall surface of the combustion chamber is suppressed. This prevents the bulkhead member from reducing the volume of the combustion chamber.

Further, in the above aspect, the corner portion included in the tool engaging portion may be chamfered.

According to this aspect, the heating of the tool engaging portion is suppressed, and the pre-ignition starting from the tool engaging portion is suppressed. By chamfering and blunting the angle, the surface area of the corner portion is reduced, heat exchange between the partition member and the combustion gas is suppressed, and the temperature rise of the partition member is suppressed.

Further, in the above aspect, the tool engaging portion is a convex portion (43) protruding from the surface of the partition wall member exposed to the main combustion chamber side, and after the partition wall member is fastened to the female screw hole. It is preferable that the structure is removable by at least one of cutting, cutting, and polishing.

According to this aspect, since the tool engaging portion can be removed, the heat capacity of the partition wall member is reduced, and the partition wall member is easily cooled by heat exchange with the intake air in the intake stroke, so that pre-ignition is suppressed.

Further, in the above aspect, an annular first locking groove (31) extending in the circumferential direction is formed on the inner peripheral surface of the female screw hole, and the first locking groove on the outer peripheral surface of the partition wall member is formed. A second locking groove (32) is formed in the facing portion, and the first locking groove and the second locking groove are provided with a C-shaped retaining ring (33) that engages with each other. It is good to be there.

According to this aspect, since the partition wall member is locked in the female screw hole by the retaining ring, the partition wall member is prevented from falling off from the female screw hole.

Further, in the above embodiment, the partition wall member has a through hole (53) having an axis inclined with respect to the axis of the female screw hole, and the through hole has an injector (41) or a spark plug (42). ) Tip should be inserted.

According to this aspect, since the tip of the injector or the spark plug supports the partition wall member, the partition wall member is prevented from falling out from the female screw hole.

According to the above configuration, it is possible to provide an auxiliary chamber structure of an internal combustion engine capable of suppressing the falling off of the partition wall member.

Sectional view of the internal combustion engine according to the first embodiment (I-I sectional view of FIG. 2) Bottom view of the cylinder head showing the wall surface of the combustion chamber according to the first embodiment. Perspective view of the partition wall member according to the first embodiment Sectional drawing of the internal combustion engine which concerns on 2nd Embodiment Perspective view of the partition wall member according to the second embodiment Perspective view of the partition wall member according to the third embodiment Sectional drawing of the internal combustion engine which concerns on 4th Embodiment Sectional drawing of the internal combustion engine which concerns on 5th Embodiment Sectional drawing of the internal combustion engine which concerns on 6th Embodiment

Hereinafter, embodiments in which the present invention is applied to an internal combustion engine will be described with reference to the drawings.

(First Embodiment)
The internal combustion engine 1 is a four-stroke engine, and as shown in FIG. 1, has an engine body 4 including a cylinder block 2 and a cylinder head 3 fastened to an upper end surface of the cylinder block 2. The cylinder block 2 is formed with a cylinder 5 having a circular cross section that opens to the upper end surface of the cylinder block 2. Let the axis of the cylinder 5 be the cylinder axis A. A portion of the lower end surface of the cylinder head 3 facing the upper end of the cylinder 5 is recessed upward to form a combustion chamber wall surface 7 forming the upper end of the cylinder 5. The combustion chamber wall surface 7 is formed in a so-called pent roof shape.

A piston 11 is reciprocally received in the cylinder 5 along the cylinder axis A. The combustion chamber wall surface 7 and the crown surface of the piston 11 cooperate to form the main combustion chamber 12. The piston 11 is connected to a crankshaft (not shown) via a connecting rod. The extending direction of the crankshaft is the crank axis direction.

As shown in FIGS. 1 and 2, two intake ports 15 and two exhaust ports 16 are open on the wall surface 7 of the combustion chamber. Assuming that the direction orthogonal to the crank axis and the cylinder axis A is the intake / exhaust direction, two intake ports 15 are arranged on the intake side, which is one side of the intake / exhaust direction, on the combustion chamber wall surface 7, and on the exhaust side, which is the other side. Two exhaust ports 16 are arranged. The open ends of the intake port 15 and the exhaust port 16 on the combustion chamber wall surface 7 side are opened and closed by the intake valve 17 and the exhaust valve 18 which are poppet valves.

A female screw hole 20 recessed upward is provided in the center of the combustion chamber wall surface 7. The female screw hole 20 is arranged coaxially with the cylinder axis A and has a female screw 20A on the inner peripheral surface. The female screw hole 20 has a bottom surface 20B at the upper end and is open at the lower end.

The partition member 23 is received in the female screw hole 20. The partition member 23 cooperates with the female screw hole 20 to form the auxiliary chamber 24. As shown in FIGS. 1 to 3, the partition wall member 23 has a cylindrical tubular portion 23A and a lower wall portion 23B that closes the lower end of the tubular portion 23A, and forms a recess 23C that opens upward. To do. A male screw 23D is formed on the outer peripheral surface of the tubular portion 23A.

The lower wall portion 23B is curved so that the central portion is convex downward. An annular tool engaging portion 26 centered on the axis of the partition wall member 23 is formed on the outer peripheral portion of the outer surface of the lower wall portion 23B exposed to the main combustion chamber 12 side. The tool engaging portion 26 includes a plurality of recesses 27 recessed inward in the radial direction from the outer peripheral surface of the partition wall member 23. Each recess 27 is defined by an upper wall surface 27A substantially orthogonal to the axis of the partition wall member 23 and two side wall surfaces 27B hanging from the upper wall surface 27A, respectively, and opens downward and outward in the radial direction. The boundary between the two side wall surfaces 27B forms a vertically extending corner portion, and is located most radially inward in the recess 27. Each recess 27 is formed in a rotationally symmetric shape centered on the axis of the partition member 23, and 12 recesses 27 are continuously arranged in the circumferential direction. The number of recesses 27 can be arbitrarily set, and may be, for example, six.

The lower wall portion 23B is formed with a plurality of communication holes 34 that penetrate in the thickness direction and communicate the main combustion chamber 12 and the sub chamber 24. The communication holes 34 extend linearly, and their axes intersect each other at one intersection in the sub-chamber 24. That is, each communication hole 34 extends radially around the intersection of the axes of the communication hole 34. Each communication hole 34 is formed in a rotationally symmetrical shape about the axis of the partition member 23, and each intersection is located on the axis of the partition member 23 that coincides with the cylinder axis A. In the present embodiment, 12 communication holes 34 are provided and arranged at equal intervals in the circumferential direction around the axis of the partition wall member 23. The open end of each communication hole 34 on the main combustion chamber 12 side is open at the bottom of each recess 27, that is, at the boundary between the two side wall surfaces 27B. By opening the communication hole 34 in the tool engaging portion 26 in this way, the arrangement space of the tool engaging portion 26 and the communication hole 34 can be reduced, and the amount of protrusion of the partition wall member 23 from the combustion chamber wall surface 7 Can be made smaller.

A tightening torque can be applied to the partition wall member 23 by engaging the tool corresponding to the tool engaging portion 26 and rotating the tool. The tool has a plurality of protrusions that can be engaged with each recess 27. By tightening with a tool, the upper end surface 23E of the tubular portion 23A of the partition wall member 23 can be pressed against the bottom surface 20B of the female screw hole 20 to generate a compression reaction force in the tubular portion 23A. Due to the compression reaction force, the threads of the female screw 20A and the male screw 23D are pressed against each other, the rotation of the partition member 23 with respect to the female screw hole 20 is suppressed, and the partition member 23 is prevented from falling off.

A first locking groove 31 that is recessed outward in the radial direction and extends in an annular shape in the circumferential direction is formed on the bottom surface 20B side portion of the inner peripheral surface of the female screw hole 20. A second locking groove 32 that is recessed inward in the radial direction and extends in an annular shape in the circumferential direction is formed at the end of the tubular portion 23A on the side opposite to the lower wall portion 23B of the outer peripheral surface. With the partition wall member 23 mounted in the female screw hole 20, the first locking groove 31 and the second locking groove 32 face each other in the radial direction.

As shown in FIG. 1, a C-shaped retaining ring 33 is mounted on the first locking groove 31 and the second locking groove 32. The retaining ring 33 extends along the first locking groove 31 and the second locking groove 32, engages with the first locking groove 31 in the vertical direction on the outer peripheral side portion, and is second on the inner peripheral side portion. It engages with the locking groove 32 in the vertical direction to restrict the vertical movement of the partition member 23 with respect to the female screw hole 20. As described above, the first locking groove, the second locking groove 32, and the retaining ring 33 function as means for preventing the partition wall member 23 from falling off. The partition wall member 23 is screwed into the female screw hole 20 together with the retaining ring 33 by mounting the retaining ring 33 in the second locking groove 32 and burying the retaining ring 33 in the second locking groove 32 by elastic deformation. Can be done. When the partition member 23 is screwed into the female screw hole 20 to a predetermined position, the first locking groove 31 and the second locking groove 32 face each other, the retaining ring 33 is restored, and the outer peripheral side portion is first engaged. It rushes into the blind groove 31.

In another embodiment, the retaining ring 33 is located in the second locking groove 32 when the internal combustion engine 1 is stopped, and expands when the internal combustion engine 1 is driven and is hot. It may be configured to be located at a position straddling the stop groove 31 and the second locking groove 32. For example, the retaining ring 33 may be formed of a material having a coefficient of thermal expansion equal to or higher than the coefficient of thermal expansion of the material of the cylinder head 3. Since the retaining ring 33 becomes hotter than the cylinder head 3 when it is hot, the retaining ring 33 expands more than the cylinder head 3 and can enter the first locking groove 31. According to this configuration, since the retaining ring 33 is located in the second locking groove 32 when it is cold, the partition wall member 23 can be attached and detached.

The corner portion 28 included in the tool engaging portion 26, that is, the ridge portion defining the edge of the recess 27 is preferably chamfered. The corner 28 is exposed to the main combustion chamber 12 and has a large surface area. Therefore, the temperature tends to be higher than that of other parts, which may be the starting point of pre-ignition. By blunting the corner 28 by chamfering, the surface area is reduced and the temperature rise is suppressed.

The cylinder head 3 is formed with a connection passage 35 extending upward from the center of the bottom surface 20B of the female screw hole 20, an injector hole 36 connected to the connection passage 35, and a spark plug hole 37. The connection passage 35 is connected to the recess 23C of the partition wall member 23 at the lower end to form a part of the sub chamber 24. The injector hole 36 and the spark plug hole 37 are opened on the upper surface of the cylinder head 3 at the upper end and are connected to the upper end of the connection passage 35 at the lower end. The injector hole 36 is arranged on a plane orthogonal to the crank axis and is inclined upward toward the intake side. The injector holes 36 are arranged between the adjacent intake ports 15 when viewed from the direction along the cylinder axis A. The spark plug hole 37 is arranged on a plane orthogonal to the crank axis and is inclined upward toward the exhaust side. The injector holes 36 are arranged between the adjacent exhaust ports 16 when viewed from the direction along the cylinder axis A.

The injector 41 is inserted into the injector hole 36. The injector 41 is a means for injecting liquid fuel or gaseous fuel. The injector 41 has a nozzle 41A having a nozzle for injecting fuel at the tip thereof. The injector 41 is arranged so that the tip of the nozzle 41A provided with the injection hole is located in the connection passage 35.

A spark plug 42 is inserted into the spark plug hole 37. The spark plug 42 has a main body portion 42A extending in a shaft shape, a center electrode 42B provided at the center of the tip of the main body portion 42A, and a ground electrode 42C protruding from the peripheral edge of the tip of the main body portion 42A. A male screw is formed on the outer peripheral surface of the main body portion 42A, and is screwed into a female screw formed in the lower part of the spark plug hole 37. A ignition portion is formed between the center electrode 42B and the tip of the ground electrode 42C, and sparks are generated by applying a voltage to the center electrode 42B at the time of ignition. The center electrode 42B and the ground electrode 42C are arranged in the connecting passage 35.

A recess 45 recessed upward is formed in a portion of the combustion chamber wall surface 7 between the two intake ports 15. The cylinder head 3 is formed with a second injector hole 46 extending from the outer surface on the intake side to the side surface of the recess 45. The second injector 47 is inserted into the second injector hole 46. The injection hole at the tip of the second injector 47 is arranged in the main combustion chamber 12, and fuel is injected toward the main combustion chamber 12.

The effect of the internal combustion engine 1 configured as described above will be described. Since the partition member 23 has the tool engaging portion 26, the tool can be engaged with the tool engaging portion 26 to apply a tightening torque to the partition member 23. Therefore, the partition wall member 23 can be screwed into the female screw hole 20, and the upper end surface 23E of the partition wall member 23 can be pressed against the bottom surface 20B of the female screw hole 20. As a result, a compression reaction force is generated in the partition member 23, and the female screw 20A and the male screw 23D are in pressure contact with each other to suppress the rotation of the partition member 23 with respect to the female screw hole 20. That is, the partition member 23 can be fastened to the female screw hole 20.

Since the communication hole 34 opens in the recess 27 of the tool engaging portion 26 and the tool engaging portion 26 and the communication hole 34 are provided at the same position, the amount of protrusion of the partition wall member 23 from the combustion chamber wall surface 7 is suppressed. Can be done. As a result, it is possible to prevent the partition member 23 from reducing the volume of the main combustion chamber 12.

Since the corner 28 of the tool engaging portion 26 is chamfered, the surface area of the corner 28 is reduced, heat exchange between the partition member 23 and the combustion gas is suppressed, and heating of the tool engaging portion 26 is suppressed. .. As a result, pre-ignition starting from the tool engaging portion 26 is suppressed.

(Second Embodiment)
In the second embodiment, the positions of the communication holes 34 in the partition wall member 23 are different from those in the first embodiment, and the other configurations are the same. As shown in FIGS. 4 and 5, in the partition member 23 according to the second embodiment, the opening end of each communication hole 34 on the main combustion chamber 12 side is on the center side of the tool engaging portion 26 of the lower wall portion 23B. It has an opening on the surface. The communication hole 34 may be arranged at a position deviated from the tool engaging portion 26, and may have an arbitrary angle with respect to the cylinder axis A.

(Third Embodiment)
In the third embodiment, the positions of the tool engaging portion 26 and the communication hole 34 in the partition wall member 23 are different from those in the first embodiment, and the other configurations are the same. As shown in FIG. 6, in the partition wall member 23 according to the third embodiment, the tool engaging portion 26 is a convex portion 51 projecting from the center of the surface of the lower wall portion 23B exposed to the main combustion chamber 12 side. .. The convex portion 51 may be formed on, for example, a hexagonal column or a square column. The convex portion 51 may be arranged inside the plurality of communication holes 34 arranged on the circumference of the lower wall portion 23B. Further, the convex portion 51 is configured to be removable by at least one of cutting, cutting, and polishing after the fastening member is fastened to the female screw hole 20. That is, after the partition member 23 is assembled into the female screw hole 20, the tool engaging portion 26 which is the convex portion 51 is removed and does not exist in the lower wall portion 23B.

By removing the tool engaging portion 26, the volume of the main combustion chamber 12 increases. Further, by removing the tool engaging portion 26 from the partition wall member 23, the heat capacity of the partition wall member 23 is reduced, and the partition wall member 23 is easily cooled in the intake stroke. As a result, the temperature of the partition member 23 is lowered, and pre-ignition starting from the partition member 23 is suppressed. Since the convex portion 51 is arranged on the tip side of the plurality of communication holes 34 in the lower wall portion 23B, it is difficult for chips of the convex portion 51 to enter the communication hole 34 when the convex portion 51 is removed by cutting or the like. ..

(Fourth Embodiment)
In the fourth embodiment, the first locking groove 31, the second locking groove 32, and the retaining ring 33 as the means for preventing the partition wall member 23 from falling off are omitted as compared with the first to third embodiments. Further, as shown in FIG. 7, the spark plug hole 37 is opened on the inner peripheral surface of the female screw hole 20, and is an insertion hole that penetrates the tubular portion 23A of the partition wall member 23 in the thickness direction and connects to the spark plug hole 37. 53 is formed. The spark plug hole 37 and the insertion hole 53 are arranged coaxially with each other and are arranged so as to be inclined with respect to the cylinder axis A. The tip of the spark plug 42 plunges into the insertion hole 53 to restrict the rotation of the partition member 23 with respect to the female screw hole 20. As a result, the partition member 23 is prevented from falling off with respect to the female screw hole 20. In this case, the injector hole 36 and the injector 41 may be arranged along the cylinder axis A.

(Fifth Embodiment)
In the fifth embodiment, the first locking groove 31, the second locking groove 32, and the retaining ring 33 as the means for preventing the partition wall member 23 from falling off are omitted as compared with the first to third embodiments. Further, as shown in FIG. 8, the injector hole 36 is opened on the inner peripheral surface of the female screw hole 20, and the insertion hole 53 penetrates the tubular portion 23A of the partition wall member 23 in the thickness direction and connects to the spark plug hole 37. Is formed. The injector hole 36 and the insertion hole 53 are arranged coaxially with each other and are arranged so as to be inclined with respect to the cylinder axis A. The tip of the nozzle 41A of the injector 41 rushes into the insertion hole 53 and restricts the rotation of the partition member 23 with respect to the female screw hole 20. As a result, the partition member 23 is prevented from falling off with respect to the female screw hole 20. In this case, the spark plug hole 37 and the spark plug 42 may be arranged along the cylinder axis A.

(Sixth Embodiment)
In the sixth embodiment, the first locking groove 31, the second locking groove 32 and the retaining ring 33 as the means for preventing the partition wall member 23 from falling off are omitted as compared with the first to third embodiments, and the partition wall is replaced with the partition wall. The lower end of the tubular portion 23A of the member 23 is coupled to the peripheral edge of the open end of the female screw hole 20 of the combustion chamber wall surface 7 by crimping. As shown in FIG. 9, at least one locking piece 55 is projected around the female screw hole 20 of the combustion chamber wall surface 7. The locking piece 55 is crimped so as to bend inward in the radial direction after the partition member 23 is attached to the female screw hole 20. The crimped locking piece 55 plunges into the recess 27 and engages with the recess 27. When the locking piece 55 locks the recess 27, the partition member 23 is restricted from rotating with respect to the female screw hole 20. As a result, the partition wall member 23 is prevented from falling out from the female screw hole 20.

As a modification of the sixth embodiment, the locking piece 55 may abut on the outer surface of the lower wall portion 23B of the partition wall member 23 instead of the recess 27 to support the partition wall member 23 from below.

Although the description of the specific embodiment is completed above, the present invention can be widely modified without being limited to the above embodiment. For example, in order to regulate the rotation of the partition member 23 with respect to the female screw hole 20, the outer peripheral portion of the lower wall portion 23B of the partition member 23 and the edge portion of the open end of the female screw hole 20 may be welded.

1: Internal combustion engine 3: Cylinder head 7: Combustion chamber wall surface 11: Piston 12: Main combustion chamber 20: Female screw hole 23: Partition member 23A: Cylinder portion 23B: Lower wall portion 23C: Recessed portion 23D: Male screw 23E: Upper end surface 24: Sub chamber 26: Tool engaging portion 27: Recessed portion 28: Corner portion 31: First locking groove 32: Second locking groove 33: Stop ring 34: Communication hole 41: Injector 42: Spark plug 51: Convex portion 53: Insertion hole 55: Locking piece A: Cylinder axis

Claims (5)

The combustion chamber wall surface, which is formed on the lower end surface of the cylinder head and forms the main combustion chamber in cooperation with the piston,
A female screw hole recessed in the wall surface of the combustion chamber and provided with a female screw on the inner peripheral surface,
A male screw to be screwed with the female screw is provided on the outer peripheral surface, and has a partition member which is screwed into the female screw hole from the main combustion chamber side and forms a sub chamber in cooperation with the female screw hole.
It said partition member is closed and the main combustion chamber side tool engagement portion formed on the exposed outer surface, and a plurality of communication holes for connecting the auxiliary chamber and the main combustion chamber,
The tool engaging portion includes a plurality of recesses recessed inward in the radial direction from the outer peripheral surface of the partition wall member.
An auxiliary chamber structure of an internal combustion engine, characterized in that the communication hole is opened in the recess . The sub-chamber structure of an internal combustion engine according to claim 1 , wherein the corner portion included in the tool engaging portion is chamfered. The combustion chamber wall surface, which is formed on the lower end surface of the cylinder head and forms the main combustion chamber in cooperation with the piston,
A female screw hole recessed in the wall surface of the combustion chamber and provided with a female screw on the inner peripheral surface,
A male screw to be screwed with the female screw is provided on the outer peripheral surface, and has a partition member which is screwed into the female screw hole from the main combustion chamber side and forms a sub chamber in cooperation with the female screw hole.
The partition wall member has a tool engaging portion formed on an outer surface exposed on the main combustion chamber side, and a plurality of communication holes connecting the main combustion chamber and the sub chamber.
The tool engaging portion, the sub-chamber structure of the internal combustion engine you characterized in that the outer surface exposed to the main combustion chamber side of the partition wall member protrudes a convex portion which is removably formed. An annular first locking groove extending in the circumferential direction is formed on the inner peripheral surface of the female screw hole.
A second locking groove is formed on the outer peripheral surface of the partition wall member so as to face the first locking groove.
The item according to any one of claims 1 to 3 , wherein the first locking groove and the second locking groove are provided with a C-shaped retaining ring that engages with each other. The subchamber structure of the internal combustion engine described. The partition wall member has a through hole having an axis inclined with respect to the axis of the female screw hole.
The sub-chamber structure of an internal combustion engine according to any one of claims 1 to 3 , wherein the tip of an injector or a spark plug is inserted into the through hole.

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