JP2018172971A - Sub chamber structure of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sub-chamber structure of an internal combustion engine capable of suppressing a partition member from falling off. SOLUTION: A sub-chamber structure of an internal combustion engine 1 is formed at a lower end surface of a cylinder head 3, and is formed in a combustion chamber wall surface 7 which forms a main combustion chamber 12 in cooperation with a piston 11, and is recessed in the combustion chamber wall surface. A female screw hole 20 provided with an internal thread 20A on the inner peripheral surface, and a male screw 23D screwed with the female screw are provided on the outer peripheral surface. And a plurality of communication holes 34 connecting the main combustion chamber and the sub-chamber with the tool engagement portion 26 formed on the outer surface exposed to the main combustion chamber. Having. [Selection diagram] Fig. 1

Description

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

  A sub-chamber internal combustion engine having a combustion chamber partitioned into a main combustion chamber and 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-like flame that is ejected from the sub-chamber through the communication hole. The sub chamber is formed between the female screw hole and the partition member by mounting a bottomed cylindrical partition member having a male screw on the outer periphery of the female screw hole formed on the wall surface of the combustion chamber, for example (for example, Patent Documents). 1). By inserting a driving pin between the partition wall 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.

Japanese Utility Model Publication No. 5-83327

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

  In view of the above background, it is an object of the present invention to provide a sub-chamber structure for an internal combustion engine that can prevent the partition member from falling off.

  In order to solve the above-described 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 combustion chamber wall surface and provided with a female screw (20A) on the inner peripheral surface, and a male screw (23D) screwed into the female screw on the outer peripheral surface, A partition member (23) screwed in from the main combustion chamber side and forming a sub chamber (24) in cooperation with the female screw hole; and the partition member is formed on an outer surface exposed to the main combustion chamber side. Provided is a sub chamber structure of an internal combustion engine 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 and a tightening torque can be applied to the partition member, a fastening force (axial force) is generated in the partition member and the partition member is fastened to the female screw hole. be able to.

  In the above aspect, the tool engaging portion may include a plurality of concave portions (27) recessed inward in the radial direction from the outer peripheral surface of the partition wall member, and the communication hole may be opened in the concave portion. .

  According to this aspect, since the tool engaging portion and the communication hole are provided at the same position, the protruding amount of the partition wall member from the combustion chamber wall surface is suppressed. Thereby, it is avoided that a partition member reduces the volume of a combustion chamber.

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

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

  Further, in the above aspect, the tool engaging portion is a convex portion (43) protruding from a surface exposed to the main combustion chamber side of the partition member, and after the partition member is fastened to the female screw hole. It may be configured to be 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 member is reduced, and the partition member is easily cooled by heat exchange with the intake air in the intake stroke, so that preignition 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 opposing portion, and a C-shaped retaining ring (33) is provided in each of the first locking groove and the second locking groove. It is good to be.

  According to this aspect, since the partition member is locked to the female screw hole by the retaining ring, the separation of the partition member from the female screw hole is prevented.

  In the above aspect, the partition member has a through hole (53) having an axis inclined with respect to the axis of the female screw hole, and the injector (41) or the spark plug (42) is provided in the through hole. ) Is preferably inserted.

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

  According to the above configuration, it is possible to provide a sub-chamber structure for an internal combustion engine that can prevent the partition member from falling off.

Sectional drawing of the internal combustion engine which concerns on 1st Embodiment (II sectional drawing of FIG. 2) The bottom view of the cylinder head which shows the combustion chamber wall surface concerning 1st Embodiment The perspective view of the partition member concerning a 1st embodiment Sectional drawing of the internal combustion engine which concerns on 2nd Embodiment The perspective view of the partition member concerning a 2nd embodiment The perspective view of the partition member concerning a 3rd 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, an embodiment 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 has an engine body 4 including a cylinder block 2 and a cylinder head 3 fastened to the upper end surface of the cylinder block 2 as shown in FIG. 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 that faces the upper end of the cylinder 5 is recessed upward to form a combustion chamber wall surface 7 that forms 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 received in the cylinder 5 so as to reciprocate along the cylinder axis A. The combustion chamber wall surface 7 and the crown surface of the piston 11 cooperate to form a 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 defined as the crankshaft direction.

  As shown in FIGS. 1 and 2, two intake ports 15 and two exhaust ports 16 are opened in the combustion chamber wall surface 7. 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 Two exhaust ports 16 are arranged. Open ends of the intake port 15 and the exhaust port 16 on the combustion chamber wall 7 side are opened and closed by an intake valve 17 and an exhaust valve 18 which are poppet valves.

  A female screw hole 20 that is recessed upward is provided in the center of the combustion chamber wall surface 7. The female screw hole 20 is disposed 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 opens at the lower end.

  A partition wall member 23 is received in the female screw hole 20. The partition member 23 forms a sub chamber 24 in cooperation with the female screw hole 20. As shown in FIGS. 1 to 3, the partition member 23 includes a cylindrical tube portion 23 </ b> A and a lower wall portion 23 </ b> B that closes the lower end of the tube portion 23 </ b> A, and forms a recess 23 </ b> C that opens upward. To do. A male screw 23D is formed on the outer peripheral surface of the cylindrical portion 23A.

  The lower wall portion 23B is curved so that the center portion is convex downward. An annular tool engaging portion 26 centering on the axis of the partition wall member 23 is formed on the outer peripheral portion of the outer surface exposed to the main combustion chamber 12 side of the lower wall portion 23B. The tool engaging portion 26 includes a plurality of recesses 27 that are recessed radially inward from the outer peripheral surface of the partition wall member 23. Each recess 27 is defined by an upper wall surface 27A that is substantially orthogonal to the axis of the partition wall member 23 and two side wall surfaces 27B that respectively hang down from the upper wall surface 27A, and opens downward and radially outward. The boundary portion between the two side wall surfaces 27 </ b> B forms a corner portion that extends vertically, and is located at the innermost radial direction in the concave portion 27. Each of the recesses 27 is formed in a rotationally symmetrical shape with the axis of the partition wall member 23 as the center, and twelve recesses 27 are continuously arranged in the circumferential direction. In addition, the number of the recessed parts 27 can be set arbitrarily, for example, may be six.

  A plurality of communication holes 34 that penetrates in the thickness direction and communicates with the main combustion chamber 12 and the sub chamber 24 are formed in the lower wall portion 23B. Each communication hole 34 extends in a straight line, and the respective axes intersect with each other at one intersection in the sub chamber 24. That is, each communication hole 34 extends radially about the intersection of the axes of the communication holes 34. Each communication hole 34 is formed in a rotationally symmetrical shape about the axis of the partition wall member 23, and each intersection is located on the axis of the partition wall member 23 that coincides with the cylinder axis A. In the present embodiment, twelve communication holes 34 are provided, and are 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 opens at the bottom of each recess 27, that is, at the boundary between the two side wall surfaces 27B. As described above, by opening the communication hole 34 in the tool engagement portion 26, the arrangement space of the tool engagement portion 26 and the communication hole 34 can be reduced, and the protruding amount of the partition wall member 23 from the combustion chamber wall surface 7. Can be reduced.

  A tightening torque can be applied to the partition wall member 23 by engaging a tool corresponding to the tool engaging portion 26 and rotating the tool. The tool includes a plurality of convex portions that can be engaged with the respective concave portions 27. By tightening with a tool, the upper end surface 23E of the cylindrical portion 23A of the partition wall member 23 can be brought into pressure contact with the bottom surface 20B of the female screw hole 20, and a compression reaction force can be generated in the cylindrical 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, and 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 radially outward and annularly extends in the circumferential direction is formed on the bottom surface 20B side portion of the inner circumferential surface of the female screw hole 20. A second locking groove 32 that is recessed radially inward and extending annularly in the circumferential direction is formed at the end opposite to the lower wall portion 23B of the outer peripheral surface of the cylindrical portion 23A. In a state where the partition wall member 23 is 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 attached to 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 at the outer peripheral side portion, and is second at the inner peripheral side portion. The engaging groove 32 is engaged in the vertical direction, and the vertical movement of the partition wall member 23 with respect to the female screw hole 20 is restricted. Thus, the first locking groove, the second locking groove 32, and the retaining ring 33 function as a means for preventing the partition member 23 from falling off. By attaching a retaining ring 33 to the second retaining groove 32 and burying the retaining ring 33 in the second retaining groove 32 by elastic deformation, the partition wall member 23 is screwed into the female screw hole 20 together with the retaining ring 33. Can do. 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 in the first engagement. It rushes into the stop groove 31.

  In another embodiment, the retaining ring 33 is located in the second locking groove 32 when the internal combustion engine 1 is cold, and expands when the internal combustion engine 1 is driving and expands to the first engagement. You may comprise so that it may be located in the position over the stop groove 31 and the 2nd locking groove 32. FIG. For example, the retaining ring 33 may be formed of a material having a thermal expansion coefficient equal to or higher than that of the cylinder head 3. Since the retaining ring 33 is hotter than the cylinder head 3 when hot, the retaining ring 33 can expand more than the cylinder head 3 and enter the first locking groove 31. According to this configuration, the retaining ring 33 is located in the second locking groove 32 when cold, so that 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 concave portion 27 is preferably chamfered. The corner portion 28 is exposed to the main combustion chamber 12 and has a large surface area. Therefore, it tends to become high temperature with respect to other parts, and there is a possibility of becoming a starting point of pre-ignition. When the corners 28 are blunted by chamfering, the surface area is reduced and the temperature rise is suppressed.

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

  An injector 41 is inserted into the injector hole 36. The injector 41 is means for injecting liquid fuel or gaseous fuel. The injector 41 has a nozzle 41A having a nozzle hole for injecting fuel at the tip. The injector 41 is arranged so that the tip of the nozzle 41 </ b> A having the nozzle hole is located in the connection passage 35.

  A spark plug 42 that is a spark plug is inserted into the spark plug hole 37. The spark plug 42 has a main body portion 42A extending in an axial 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 42 </ b> A and is screwed into a female screw formed in the lower part of the spark plug hole 37. Between the center electrode 42B and the tip of the ground electrode 42C is an ignition part, and a spark is generated by applying a voltage to the center electrode 42B during ignition. The center electrode 42B and the ground electrode 42C are disposed in the connection passage 35.

  A concave portion 45 that is recessed upward is formed in a portion between the two intake ports 15 in the combustion chamber wall surface 7. 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. A second injector 47 is inserted into the second injector hole 46. The second injector 47 has a tip injection hole disposed in the main combustion chamber 12 and injects fuel 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 23 </ b> E of the partition wall member 23 can be brought into pressure contact with the bottom surface 20 </ b> B of the female screw hole 20. Thereby, a compression reaction force is generated in the partition wall member 23, the female screw 20 </ b> A and the male screw 23 </ b> D are pressed against each other, and the rotation of the partition wall member 23 with respect to the female screw hole 20 is suppressed. That is, the partition member 23 can be fastened to the female screw hole 20.

  Since the communication hole 34 opens into 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 do. Thereby, it is avoided that the partition member 23 reduces the volume of the main combustion chamber 12.

  Since the corner portion 28 of the tool engaging portion 26 is chamfered, the surface area of the corner portion 28 is reduced, heat exchange between the partition wall member 23 and the combustion gas is suppressed, and heating of the tool engaging portion 26 is suppressed. . Thereby, the pre-ignition which started from the tool engaging part 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, the partition member 23 according to the second embodiment is such that the opening end of each communication hole 34 on the main combustion chamber 12 side is closer to the center side than the tool engaging portion 26 of the lower wall portion 23B. Open on the surface. The communication hole 34 may be disposed at a position shifted from the tool engagement portion 26 and can form 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 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 protruding from the center of the surface exposed to the main combustion chamber 12 side of the lower wall portion 23B. . The convex part 51 is good to be formed, for example in the hexagonal column or the square column. The convex part 51 is good to be arrange | positioned inside the some communication hole 34 arrange | positioned on the circumference in the lower wall part 23B. 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 wall member 23 is assembled in the female screw hole 20, the tool engaging portion 26 that 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 is increased. Further, by removing the tool engaging portion 26 from the partition member 23, the heat capacity of the partition member 23 is reduced, and the partition member 23 is easily cooled during the intake stroke. Thereby, the temperature of the partition member 23 is lowered, and preignition starting from the partition member 23 is suppressed. Since the convex part 51 is arrange | positioned in the lower wall part 23B at the front end side rather than the some communication hole 34, when removing the convex part 51 by cutting etc., the chip | tip of the convex part 51 cannot enter the communication hole 34 easily. .

(Fourth embodiment)
In the fourth embodiment, the first locking groove 31, the second locking groove 32, and the retaining ring 33 are omitted as means for preventing the partition member 23 from falling out as compared with the first to third embodiments. Further, as shown in FIG. 7, the spark plug hole 37 is opened in the inner peripheral surface of the female screw hole 20, and is inserted through the cylindrical portion 23 </ b> A of the partition wall member 23 in the thickness direction and connected 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 inclined with respect to the cylinder axis A. The tip of the spark plug 42 enters the insertion hole 53 and restricts the rotation of the partition wall member 23 relative to the female screw hole 20. This prevents the partition member 23 from falling off the female screw hole 20. In this case, the injector hole 36 and the injector 41 may be disposed 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 are omitted as a means for preventing the partition wall member 23 from dropping compared to the first to third embodiments. Further, as shown in FIG. 8, the injector hole 36 opens to the inner peripheral surface of the female screw hole 20, and penetrates through the cylindrical portion 23 </ b> A of the partition wall member 23 in the thickness direction to connect 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 inclined with respect to the cylinder axis A. The tip of the nozzle 41 </ b> A of the injector 41 enters the insertion hole 53 and restricts the rotation of the partition wall member 23 with respect to the female screw hole 20. This prevents the partition member 23 from falling off the female screw hole 20. In this case, the spark plug hole 37 and the spark plug 42 may be disposed along the cylinder axis A.

(Sixth embodiment)
In the sixth embodiment, as compared with the first to third embodiments, the first locking groove 31, the second locking groove 32, and the retaining ring 33 as means for preventing the separation of the partition wall member 23 are omitted. Instead, the partition wall The lower end portion of the cylindrical 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 caulking. As shown in FIG. 9, at least one locking piece 55 protrudes around the female screw hole 20 of the combustion chamber wall surface 7. The locking piece 55 is crimped so as to bend radially inward after the partition wall member 23 is mounted in the female screw hole 20. The crimped locking piece 55 enters the recess 27 and engages with the recess 27. When the locking piece 55 locks the recess 27, the rotation of the partition wall member 23 with respect to the female screw hole 20 is restricted. Thereby, the drop-off of the partition member 23 from the female screw hole 20 is prevented.

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

  Although the description of the specific embodiment is finished as described above, the present invention is not limited to the above embodiment and can be widely modified. For example, in order to restrict the rotation of the partition wall member 23 with respect to the female screw hole 20, the outer peripheral portion of the lower wall portion 23 </ b> B of the partition wall member 23 and the edge 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: Tube portion 23B: Lower wall portion 23C: Concave portion 23D: Male screw 23E: Upper end surface 24: Sub chamber 26: Tool engaging portion 27: Recess 28: Corner portion 31: First locking groove 32: Second locking groove 33: Retaining ring 34: Communication hole 41: Injector 42: Spark plug 51: Protruding portion 53: Insertion hole 55: Locking piece A: Cylinder axis

Claims (6)

A combustion chamber wall surface formed on the lower end surface of the cylinder head and forming a main combustion chamber in cooperation with the piston;
A female screw hole recessed in the combustion chamber wall surface and provided with a female screw on the inner peripheral surface;
A partition member that includes a male screw threadedly engaged with the female screw on an outer peripheral surface, 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 member has a tool engaging portion formed on an outer surface exposed to the main combustion chamber side, and a plurality of communication holes connecting the main combustion chamber and the sub chamber. Sub-chamber structure. The tool engaging portion includes a plurality of recesses recessed inward in the radial direction from the outer peripheral surface of the partition member,
The sub-chamber structure of the internal combustion engine according to claim 1, wherein the communication hole is opened in the recess.   The subchamber structure of the internal combustion engine according to claim 1 or 2, wherein a corner portion included in the tool engaging portion is chamfered.   2. The sub-chamber structure of the internal combustion engine according to claim 1, wherein the tool engaging portion is a convex portion that protrudes from an outer surface exposed to the main combustion chamber side of the partition member and is removable. . 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 in a portion of the outer peripheral surface of the partition member facing the first locking groove,
The C-type retaining ring that engages with each of the first locking groove and the second locking groove is provided, according to any one of claims 1 to 4. A sub-chamber structure of the internal combustion engine described. The partition member has a through hole having an axis inclined with respect to the axis of the female screw hole,
The sub chamber structure of the internal combustion engine according to any one of claims 1 to 4, wherein a tip of an injector or a spark plug is inserted into the through hole.

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