JP2018172970A - Auxiliary chamber structure of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an auxiliary chamber structure of an internal combustion engine which can inhibit temperature rise of a partition wall member.SOLUTION: An auxiliary chamber structure of an internal combustion engine 1 has: a combustion chamber wall surface 7 which is formed on a lower surface of a cylinder head 3 and cooperates with a piston 11 to form a main combustion chamber 12; a reception hole 20 recessed on the combustion chamber wall surface; a partition wall member 23 which is inserted into the reception hole and cooperates with the reception hole to form an auxiliary chamber 24; a bolt hole 27 which penetrates through the cylinder head and opens on a contact surface 20C of the reception hole contacting with the partition wall member; a female screw hole 26 with a closed bottom which is formed at the partition wall member and connected with the bolt hole; a bolt 30 which is inserted into the bolt hole from the side opposite to the reception hole, threadedly engages with the female screw hole at its tip, and fastens the partition wall member to the cylinder head; and multiple coolant grooves 30D which are recessed on an outer peripheral surface of the bolt or inner peripheral surfaces of the bolt hole and the female screw hole, extend in an axial direction of the bolt, and reach a bottom part of the female screw hole.SELECTED DRAWING: Figure 2

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 by inserting and fixing a partition wall member having a bottomed cylindrical shape into a hole formed in the wall surface of the combustion chamber (for example, Patent Documents 1 and 2).

JP 2010-96089 A JP 7-63058 A

  Since the air-fuel mixture burns inside the partition member and the flame passes through the communication hole, the partition member is likely to be hotter than the wall surface forming the main combustion chamber. When the partition member becomes high temperature, the ignitability of the air-fuel mixture is improved. However, when the temperature is excessively high, it can be a starting point of preignition. Therefore, it is preferable to suppress the temperature rise of the partition member.

  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 suppress an increase in temperature of a partition wall member.

  In order to solve the above-described problem, an aspect of the present invention includes a combustion chamber wall surface (7) formed on the lower surface of the cylinder head (3) and forming a main combustion chamber (12) in cooperation with the piston (11). A receiving hole (20) recessed in the combustion chamber wall surface, a partition member (23) inserted into the receiving hole and forming a sub chamber (24) in cooperation with the receiving hole, and the cylinder head And a bolt hole (27) opened in a contact surface (20C) with the partition wall member in the receiving hole, and a bottomed female screw hole (26) formed in the partition wall member and connected to the bolt hole A bolt (30) inserted into the bolt hole from the side opposite to the receiving hole, screwed into the female screw hole at the tip, and fastening the partition member to the cylinder head, and an outer peripheral surface of the bolt, or On the inner peripheral surface of the bolt hole and the female screw hole It is set to provide the auxiliary chamber structure of an internal combustion engine and having a plurality of coolant groove extending in the axial direction and connected to the bottom (32) of the female screw hole of the bolt (30D).

  According to this aspect, the partition member is fastened to the cylinder head in such a manner that it is suspended by the bolt. A passage through which the cooling water defined by the cooling water groove passes is formed between the outer peripheral surface of the bolt and the inner peripheral surface of the bolt hole and the female screw hole, and the cooling water is supplied to the bottom of the female screw hole. Since a plurality of cooling water grooves are provided, at least one of the cooling water grooves serves as a supply passage for supplying cooling water to the bottom of the female screw hole, and at least one other of the cooling water grooves discharges the cooling water from the bottom of the female screw hole. The cooling water flows through the bottom of the female screw hole. Thereby, a partition member is cooled with cooling water and a pre-ignition is suppressed.

  Further, in the above aspect, the cooling water inlet passage (53) and the cooling water outlet passage (54) connected to the side portion of the bolt hole are further provided, and the cooling water groove is formed on an outer peripheral surface of the bolt. It is preferable that at least one of the cooling water grooves is connected to the cooling water inlet passage, and at least one of the other cooling water grooves is connected to the cooling water outlet passage.

  According to this aspect, since the cooling water groove is formed in the bolt, it is not necessary to secure a space for forming the cooling water groove in the partition member which is a relatively small member. Moreover, when providing a cooling water groove in a volt | bolt, since a cooling water groove is formed in an outer peripheral surface, a process is easy.

  Further, in the above aspect, the bolts at the opening end (53A) of the cooling water inlet passage to the bolt hole and the opening end (54A) of the cooling water outlet passage to the bolt hole are centered. The small value of the angular widths (θ1, θ2) may be set larger than the largest value among the angles (α1, α2,..., Αn) in the circumferential direction between the cooling water grooves.

  According to this aspect, regardless of the rotation phase of the bolt, at least one of the cooling water grooves is connected to the cooling water inlet passage, and at least the other one of the cooling water grooves is connected to the cooling water outlet passage. Therefore, it is not necessary to match the rotation phase of the bolt during the fastening operation of the partition wall member, and the fastening work is facilitated.

  Further, in the above aspect, the partition member opens toward a side opposite to the main combustion chamber, and has a main body (23B) having a recess (23A) that forms a part of the sub chamber, and the main body And an ear portion (23C) protruding laterally from the portion, and the female screw hole is preferably formed in the ear portion.

  According to this aspect, it is possible to secure a space for forming the female screw hole in the partition wall member without enlarging the main body portion.

  Moreover, said aspect WHEREIN: The said receiving hole is good to be formed in the shape which the said main-body part and the said ear | edge part fit so that rotation is impossible.

  According to this aspect, it becomes easy to position the partition member with respect to the receiving hole during the fastening operation with the bolt.

  In the above aspect, the receiving hole may be provided in the center of the wall surface of the combustion chamber, and the ear portion may protrude from the main body portion in a direction parallel to the crank axis. Further, two intake ports (14) and two exhaust ports (16) are opened in the combustion chamber wall surface, and the ear portion is disposed between the adjacent intake port and exhaust port. Good.

  According to this aspect, the ear portion is arranged avoiding the intake port and the exhaust port provided on the combustion chamber wall surface.

  Further, in the above aspect, the ear portions are provided in a pair, protrude from the main body portion in parallel to the crank axis and in directions opposite to each other, the female screw holes are formed in the ear portions, and the bolts The bolt provided with the hole and the cooling water groove may be provided for each of the female screw holes.

  According to this aspect, since the partition member is fastened at the ears provided on both sides opposite to each other, the partition member is securely fastened to the cylinder head. Moreover, a partition member is cooled in both sides and a temperature rise is suppressed.

  In the above aspect, the ignition plug further includes an ignition plug (42) disposed in the sub chamber, and the ignition plug is disposed on a surface orthogonal to the crank axis and passing through the center of the combustion chamber wall surface. It is preferable that the axis is arranged.

  According to this aspect, the spark plug can be disposed avoiding the intake port and the exhaust port.

  Further, in the above aspect, the injector further includes an injector (41) disposed in the sub chamber, and the axis of the injector is on a plane orthogonal to the crank axis and passing through the center of the wall surface of the combustion chamber. Is good to be arranged.

  According to this aspect, the injector can be arranged avoiding the intake port and the exhaust port.

  According to the above structure, the subchamber structure of the internal combustion engine which can suppress the temperature rise of the partition member can be provided.

Sectional drawing of the internal combustion engine which concerns on embodiment (II sectional drawing of FIG. 4) Sectional drawing of the internal combustion engine which concerns on embodiment (II-II sectional drawing of FIG. 4) Sectional view of the cylinder head showing the surroundings of the bolt in an enlarged manner (III part enlarged view of FIG. 2) Bottom view of cylinder head showing combustion chamber wall Sectional drawing which shows the positional relationship of a volt | bolt, a cooling water inlet channel, and a cooling water outlet channel

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

  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 FIGS. 1 and 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 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 4, 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.

  As shown in FIGS. 1 to 4, a receiving hole 20 that is recessed upward is provided in the center of the combustion chamber wall surface 7. The receiving hole 20 includes a circular hole portion 20A formed coaxially with the cylinder axis A, and a pair of locking groove portions 20B recessed radially outward from the outer peripheral surface of the circular hole portion 20A. The pair of locking groove portions 20B are disposed on one side and the other side in the crank axis direction with respect to the circular hole portion 20A. In addition, each of the pair of locking grooves 20B is disposed between the intake port 15 and the exhaust port 16 adjacent to each other. The bottom surface 20 </ b> C of the receiving hole 20 is formed by a circular hole portion 20 </ b> A and upper end surfaces of the pair of locking groove portions 20 </ b> B, and is formed in a continuous plane orthogonal to the cylinder axis A.

  A partition wall member 23 is received in the receiving hole 20. The partition member 23 forms a sub chamber 24 in cooperation with the receiving hole 20. The partition member 23 has a main body portion 23B having a concave portion 23A that opens upward and forms part of the sub chamber 24, and a pair of ear portions 23C that protrude laterally from the main body portion 23B. The main body portion 23B includes a cylindrical portion 23D having a circular cross section whose axis extends vertically and a lower wall portion 23E that closes the lower end of the cylindrical portion 23D. Each ear 23C protrudes radially outward from the outer periphery of the main body 23B and in directions opposite to each other.

  As shown in FIG. 4, when viewed from the direction along the cylinder axis A, the outer shape of the partition wall member 23 formed by the main body portion 23B and the pair of ear portions 23C is formed by the circular hole portion 20A and the pair of locking groove portions 20B. It is formed in a shape complementary to the outer shape of the receiving hole 20 to be formed. Thereby, when the partition member 23 is inserted into the receiving hole 20 from below, the main body portion 23B is fitted into the circular hole portion 20A, and each ear portion 23C is fitted into the corresponding locking groove portion 20B. When the pair of ear portions 23C are locked in the corresponding locking groove portions 20B, the partition wall member 23 is fitted in the receiving hole 20 so as not to rotate.

  As shown in FIGS. 1 and 2, a continuous flat upper end surface 23 </ b> F is formed at the upper end of the main body 23 </ b> B and each ear 23 </ b> C of the partition wall member 23. The partition member 23 is in contact with the bottom surface 20C of the receiving hole 20 at the upper end surface 23F. As shown in FIGS. 2 and 3, each ear portion 23 </ b> C is formed with a bottomed female screw hole 26 opened to the upper end surface 23 </ b> F. Each female screw hole 26 extends in parallel with the cylinder axis A.

  The cylinder head 3 is formed with a bolt hole 27 having a circular cross section penetrating vertically in a portion corresponding to each female screw hole 26. The lower end of each bolt hole 27 opens to the bottom surface 20 </ b> C of the receiving hole 20, and the upper end opens to the upper surface of the cylinder head 3. Counterbore 28 is formed around each bolt hole 27 on the upper surface of the cylinder head 3. The bolt hole 27 and the female screw hole 26 corresponding to each other are connected coaxially and extend linearly in parallel with the cylinder axis A.

  A bolt 30 is inserted into the bolt hole 27 and the female screw hole 26 connected to each other. The bolt 30 has a cylindrical shaft portion 30A, a head portion 30B provided at the base end of the shaft portion 30A, and a male screw 30C provided on the outer peripheral surface of the distal end of the shaft portion 30A. A plurality of cooling water grooves 30 </ b> D are recessed in the outer peripheral surface of the shaft portion 30 </ b> A. Each cooling water groove 30D extends linearly in the axial direction of the shaft portion 30A, crosses the male screw 30C, and reaches the tip of the shaft portion 30A.

  Each bolt 30 is inserted into the bolt hole 27 from the end (upper end) opposite to the receiving hole 20, the tip projects into the female screw hole 26, and is screwed into the female screw hole 26 at the male screw 30 </ b> C at the tip. . The head 30B of the bolt 30 is in contact with the upper surface of the cylinder head 3 via a seal member. In this way, the partition wall member 23 is fastened to the cylinder head 3 by each bolt 30. In other words, the partition wall member 23 is suspended in the receiving hole 20 by each bolt 30.

  The cross-sectional area of each cooling water groove 30D is the cross-sectional area of the gap between the outer peripheral surface of the male screw 30C and the inner peripheral surface of the female screw hole 26, and the crossing of the gap between the outer peripheral surface of the shaft portion 30A and the inner peripheral surface of the bolt hole 27. It is formed sufficiently large for each of the areas.

  In a state where the cylinder head 3 and the partition wall member 23 are fastened to each other by the bolt 30, a space 32 is formed between the tip of the shaft portion 30A and the female screw bottom portion. One end of each cooling water groove 30 </ b> D is connected to the space 32.

  As shown in FIGS. 1 and 2, the lower wall portion 23 </ b> E of the partition wall member 23 is formed in a substantially hemispherical shape that protrudes downward, and protrudes downward from the combustion chamber wall surface 7. A surface (lower surface) of the lower wall portion 23 </ b> E facing the main combustion chamber 12 side is formed in a plane that is smoothly connected to the combustion chamber wall surface 7. The recess 23A of the partition wall member 23 forming the sub chamber 24 is formed in a substantially spherical shape. 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 23E. 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 around the intersection. 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, six 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 main combustion chamber 12 and the sub chamber 24 are communicated with each other only by a plurality of communication holes 34 so that fluid can be circulated. The main combustion chamber 12 and the sub chamber 24 are separated from each other in portions other than the communication hole 34, and the flow of fluid is blocked.

  In the cylinder head 3, a connection passage 35 extending upward from the center of the bottom surface 20 </ b> C of the receiving 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> A 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 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.

  The cylinder head 3 is formed with a head-side water jacket 50 through which cooling water flows. The head-side water jacket 50 is formed mainly around the combustion chamber wall surface 7 and the exhaust port 16. The head-side water jacket 50 includes a head-side cooling water inlet 50A opened at the lower end surface of the cylinder head 3, and a head-side cooling water outlet (not shown) opened at one end surface in the crank axis direction of the cylinder head 3. Have.

  A block-side water jacket 51 is formed around the cylinder 5 of the cylinder block 2. The block-side water jacket 51 has a block-side cooling water inlet (not shown) that opens to the side surface of the cylinder block 2 and a block-side cooling water outlet 51 </ b> A that opens to the upper end surface of the cylinder block 2.

  The head side cooling water inlet 50A and the block side cooling water outlet 51A are connected to each other, and the block side cooling water inlet and the head side cooling water outlet are connected to a cooling water passage provided with a water pump. The cooling water circulates through the block-side water jacket 51 and the head-side water jacket 50 in this order by a water pump.

  As shown in FIGS. 2 and 3, the cylinder head 3 is formed with a cooling water inlet passage 53 and a cooling water outlet passage 54 that connect the head side water jacket 50 and the bolt hole 27. The cooling water inlet passage 53 is connected to a portion of the head-side water jacket 50 where the cooling water pressure is higher than the portion where the cooling water outlet passage 54 is connected. For example, the cooling water inlet passage 53 is connected to a portion closer to the head side cooling water inlet 50 </ b> A than a portion where the cooling water outlet passage 54 is connected in the head side water jacket 50.

  The cooling water inlet passage 53 and the cooling water outlet passage 54 are connected to the side portion of the bolt hole 27. When viewed from the direction along the axis of the bolt hole 27, the cooling water inlet passage 53 has an opening end 53A (connection end) on the bolt hole 27 side and the cooling water outlet passage 54 has an opening end 54A (connection end) on the bolt hole 27 side. Are arranged offset in the circumferential direction so as not to overlap each other. The cooling water inlet passage 53 is connected to at least one of the cooling water grooves 30D, and the cooling water outlet passage 54 is connected to at least one of the cooling water grooves 30D other than the one connected to the cooling water inlet passage 53. .

As shown in FIG. 5, around the axis of the bolt hole 27, the angular width of the opening end 53A of the cooling water inlet passage 53 is θ1, the angular width of the opening end 54A of the cooling water outlet passage 54 is θ2, and each cooling water groove When the angles (intervals) in the circumferential direction between 30D are α1, α2,... Αn, it is preferable to satisfy the following relational expression (1).
max (α1, α2,..., αn) <min (θ1, θ2) (1)
That is, the smaller value of the angular width θ1 of the opening end 53A of the cooling water inlet passage 53 and the angular width θ2 of the opening end 54A of the cooling water outlet passage 54 is the angle in the circumferential direction between the cooling water grooves 30D. It is better to set it larger than the largest value. By satisfying this relational expression (1), the cooling water inlet passage 53 is connected to at least one cooling water groove 30D regardless of the rotation angle of the bolt 30, and the cooling water outlet passage 54 is connected to the cooling water groove 30D. It connects with at least one other than what was connected with the cooling water inlet channel 53. Thereby, the fastening operation | work by the volt | bolt 30 becomes easy.

  Further, since the opening end 53A of the cooling water inlet passage 53 and the opening end 54A of the cooling water outlet passage 54 should not be connected to each other, the angle width θ1 of the opening end 53A of the cooling water inlet passage 53 and the cooling water outlet passage 54 are set. The smaller value of the angular width θ2 of the opening end 54A is always set to a value smaller than 180 °. In this case, the number of cooling water grooves 30D is always 3 or more.

  Further, assuming that the angle widths around the axis of the bolt hole 27 of each cooling water groove 30D are β1, β2,... Βn, the opening end 53A of the cooling water inlet passage 53 and the opening end 54A of the cooling water outlet passage 54 are provided. Is set larger than the largest value among the angular widths (β1, β2,... Βn) of each cooling water groove 30D. Thereby, it is avoided that one cooling water groove 30 </ b> D is connected to both the cooling water inlet passage 53 and the cooling water outlet passage 54. The total angular width of each cooling water groove 30D is always set to a value smaller than 360 °.

  In the present embodiment, since four cooling water grooves 30D are provided at equal intervals in the circumferential direction, the angles α1 to α4 between the cooling water grooves 30D are all 90 °. Therefore, the angular width θ1 of the opening end 53A of the cooling water inlet passage 53 and the angular width θ2 of the opening end 54A of the cooling water outlet passage 54 are preferably set to values larger than 90 ° and smaller than 180 °.

  Hereinafter, effects of the internal combustion engine 1 according to the present embodiment will be described. The cooling water flowing through the head-side water jacket 50 is at least one cooling water groove 30 </ b> D connected to the cooling water inlet passage 53 and the cooling water inlet passage 53 due to a pressure difference between the cooling water inlet passage 53 and the cooling water outlet passage 54. The space 32 provided at the bottom of the female screw hole 26, at least one cooling water groove 30 </ b> D connected to the cooling water outlet passage 54, and the cooling water outlet passage 54 are sequentially passed back to the head side water jacket 50. The partition wall member 23 is cooled by the cooling water passing through the space 32 inside the partition wall member 23, and preignition starting from the partition wall member 23 is suppressed.

  The cross-sectional area of each cooling water groove 30D is the cross-sectional area of the gap between the outer peripheral surface of the male screw 30C and the inner peripheral surface of the female screw hole 26, and the crossing of the gap between the outer peripheral surface of the shaft portion 30A and the inner peripheral surface of the bolt hole 27. Since it is formed sufficiently large for each of the areas, the cooling water flows through the cooling water groove 30D.

  The plurality of cooling water grooves 30D form both a supply path for supplying cooling water to the space 32 formed at the bottom of the female screw hole 26 and a discharge path for discharging cooling water from the space 32. Can flow through the space 32.

  Since the cooling water groove 30D is formed in the bolt 30, it is not necessary to secure a space for forming the cooling water groove 30D in the partition member 23 which is a relatively small member. Moreover, when providing the cooling water groove 30D in the volt | bolt 30, since the cooling water groove 30D is formed in an outer peripheral surface, a process is easy. Further, when the cooling water groove 30D is processed into the bolt 30 and the cooling water groove 30D is processed into the bolt hole 27 of the cylinder head 3 and the female screw hole 26 of the partition wall member 23, the processing target is more. Therefore, the work load is reduced.

  Since the partition member 23 is configured to be fitted in the receiving hole 20 so as not to rotate, the partition member 23 can be easily positioned with respect to the cylinder head 3. In addition, since the partition wall member 23 is fastened to the cylinder head 3 by the bolt 30 penetrating the cylinder head 3, there is a low possibility that the partition member 23 falls into the main combustion chamber 12. Further, since the bolt 30 is not exposed to the main combustion chamber 12 and is not exposed to the combustion gas, deterioration is suppressed and the partition wall member 23 can be reliably supported. Further, since the bolt 30 is cooled by the cooling water passing through the cooling water groove 30D, thermal expansion and restoration due to a temperature change at the time of operation and stop of the internal combustion engine 1 are suppressed, and it is difficult for the fastening portion to be loosened. .

  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, the cooling water groove 30 </ b> D may be formed on the inner peripheral surfaces of the bolt hole 27 and the female screw hole 26 instead of the outer peripheral surface of the shaft portion 30 </ b> A of the bolt 30.

  One of the injector hole 36 and the spark plug hole 37 may be disposed coaxially with the cylinder axis. In another embodiment, the injector hole 36 may be connected to the wall surface of the combustion chamber wall 7 or the wall surface of the intake port 15 instead of the connection passage 35. In this case, the injector 41 injects fuel not toward the sub chamber 24 but toward the main combustion chamber 12 or the intake port 15.

  In the axial direction of the bolt hole 27, the relative positions of the opening end 53A of the cooling water inlet passage 53 and the opening end 54A of the cooling water outlet passage 54 may coincide with each other or may be offset.

  A female screw may be provided on the inner peripheral surface of the bolt hole 27, and a male screw that engages with the female screw on the inner peripheral surface of the bolt hole 27 may be provided on the shaft portion 30 </ b> A of the bolt 30. In this case, the opening end 53 </ b> A of the cooling water inlet passage 53 and the opening end 54 </ b> A of the cooling water outlet passage 54 may be arranged at a portion where the internal thread of the bolt hole 27 is provided.

1: Internal combustion engine 3: Cylinder head 7: Combustion chamber wall surface 12: Main combustion chamber 15: Intake port 16: Exhaust port 20: Receiving hole 20C: Bottom surface 23: Partition member 23A: Recess 23B: Main body portion 23C: Ear portion 23F: Upper end surface 24: Sub chamber 26: Female screw hole 27: Bolt hole 30: Bolt 30A: Shaft portion 30B: Head portion 30C: Male screw 30D: Cooling water groove 32: Space 34: Communication hole 35: Connection passage 36: Injector hole 37: Spark plug hole 41: Injector 42: Spark plug 50: Head side water jacket 53: Cooling water inlet passage 53A: Open end 54: Cooling water outlet passage 54A: Open end A: Cylinder axis

Claims (10)

A combustion chamber wall formed on the lower surface of the cylinder head and forming a main combustion chamber in cooperation with the piston;
A receiving hole recessed in the combustion chamber wall;
A partition member which is inserted into the receiving hole and forms a sub chamber in cooperation with the receiving hole;
A bolt hole penetrating the cylinder head and opening in a contact surface with the partition member in the receiving hole;
A bottomed female screw hole formed in the partition member and connected to the bolt hole;
A bolt inserted into the bolt hole from the side opposite to the receiving hole, screwed into the female screw hole at the tip, and fastening the partition member to the cylinder head;
And a plurality of cooling water grooves that are recessed in the outer peripheral surface of the bolt or in the inner peripheral surfaces of the bolt hole and the female screw hole, and extend in the axial direction of the bolt and are connected to the bottom of the female screw hole. A sub chamber structure of the internal combustion engine. A cooling water inlet passage and a cooling water outlet passage connected to the side of the bolt hole;
The cooling water groove is formed on the outer peripheral surface of the bolt, reaches the tip of the bolt,
The sub chamber of the internal combustion engine according to claim 1, wherein at least one of the cooling water grooves is connected to the cooling water inlet passage, and at least one of the other cooling water grooves is connected to the cooling water outlet passage. Construction.   The smaller value of the angular widths around the bolts at the opening end to the bolt hole of the cooling water inlet passage and the opening end to the bolt hole of the cooling water outlet passage is the distance between the cooling water grooves. The sub-chamber structure of the internal combustion engine according to claim 2, wherein the sub-chamber structure is set to be larger than the largest value among the angles in the circumferential direction. The partition member has a main body portion that opens toward a side opposite to the main combustion chamber and has a concave portion that forms a part of the sub chamber, and an ear portion that protrudes laterally from the main body portion. ,
The sub-chamber structure of the internal combustion engine according to any one of claims 1 to 3, wherein the female screw hole is formed in the ear portion.   The sub-chamber structure of the internal combustion engine according to claim 4, wherein the receiving hole is formed in a shape in which the main body portion and the ear portion are fitted so as not to rotate. The receiving hole is provided at the center of the combustion chamber wall surface,
The sub chamber structure of the internal combustion engine according to claim 4 or 5, wherein the ear portion protrudes from the main body portion in a direction parallel to the crank axis. Two intake ports and two exhaust ports open in the combustion chamber wall surface,
The sub chamber structure of the internal combustion engine according to claim 6, wherein the ear portion is disposed between the adjacent intake port and the exhaust port. The ear portions are provided in a pair, and protrude from the main body portion in parallel to the crank axis and in directions opposite to each other
The female screw hole is formed in each of the ear portions,
The sub-chamber structure of the internal combustion engine according to claim 6 or 7, wherein the bolt provided with the bolt hole and the cooling water groove is provided for each of the female screw holes. The ignition part further has a spark plug disposed in the sub chamber,
9. The axis of the spark plug is disposed on a plane that is orthogonal to the crank axis and passes through the center of the wall surface of the combustion chamber. 9. The internal combustion engine subchamber structure. The nozzle further includes an injector disposed in the sub chamber;
10. The axis of the injector according to claim 6, wherein the axis of the injector is arranged on a plane orthogonal to the crank axis and passing through a center of the wall surface of the combustion chamber. Sub chamber structure of an internal combustion engine.

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