JP2008075499A - Engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine capable of securing arrangement space of head bolts without expanding total length and total width of the engine. <P>SOLUTION: In the engine provided with a cylinder block including a plurality of one side and the other side cylinder bores arranged zigzag to be positioned alternately in a crankshaft direction, and a cylinder head joined on a mating surface of the cylinder block by head bolts, the head bolts comprise center bolts arranged between one side and the other side cylinder bores adjoining in a crankshaft perpendicular direction, and side head bolts arranged in crankshaft perpendicular direction both sides of one side and the other side cylinder bores with putting the center head bolts therebetween, and bolt seat surfaces on which the center head bolts are fastened are formed at positions further from the mating surface than bolt seat surfaces on which the side head bolts are fastened. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an engine including a cylinder block having a plurality of cylinder bores arranged in a staggered manner so as to be alternately positioned in the crankshaft direction, and a cylinder head coupled to the cylinder block with a head bolt, and in particular, the arrangement of the head bolt. Concerning structure.

In an engine having a plurality of cylinder bores, the plurality of cylinder bores are alternately positioned in the crankshaft direction in order to make the crankshaft direction dimension (total engine length) and the crankshaft perpendicular direction dimension (engine full width) compact. In some cases, staggered arrangement (see, for example, Non-Patent Document 1).
ATZ / MTZ / July 2002 issue, D58922, "VWPHAETON special issue"

  In the above-mentioned conventional staggered arrangement engine, the one side and the other side cylinder bores are arranged in a staggered manner so that they are alternately positioned in the crankshaft direction, so there is almost no margin space between the one side cylinder bore and the other side cylinder bore. It is extremely difficult to secure a space for arranging the head bolt that fastens the cylinder head and the cylinder block. For this reason, in the conventional engine, the space for arranging the head bolts is secured by increasing the distance in the crankshaft direction between the one and other cylinder bores or the distance in the direction perpendicular to the crankshaft.

  As a result, the overall engine length becomes longer when the cylinder bore spacing in the crankshaft direction is widened, and the overall engine width becomes larger when the crankshaft perpendicular spacing is widened, making the engine more compact by staggering the cylinder bores. There is a problem that the effect decreases. Further, when the interval between the cylinder bores in the direction perpendicular to the crankshaft is increased, the combustion chamber shape and the piston shape become distorted, which is disadvantageous in ensuring engine performance.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide an engine that can secure a space for arranging head bolts without increasing the overall length or the overall width of the engine.

  The invention according to claim 1 is a cylinder block having a plurality of one-side and other-side cylinder bores arranged in a staggered manner so as to be alternately positioned in the crankshaft direction, and a cylinder head coupled to a mating surface of the cylinder block with a head bolt The head bolt includes a center head bolt disposed between the one side and the other side cylinder bores adjacent to each other in a direction perpendicular to the crankshaft, and the one side and the other with the center head bolt interposed therebetween. A side head bolt disposed on both sides of the cylinder bore in a direction perpendicular to the crankshaft, and the bolt seat surface to which the center head bolt is fastened is more than the bolt seat surface to which the side bed bolt is fastened. It is characterized by being formed at a position distant from.

  According to a second aspect of the present invention, in the first aspect, the center head bolt is disposed between spring seats in which the valve springs of the one side and other side cylinder bore intake valves and the exhaust valves adjacent to each other in the direction perpendicular to the crankshaft are disposed. The bolt seat surface of the center head bolt is formed at a position farther from the mating surface than the spring seat.

  A third aspect of the present invention provides the first or second cylinder bore according to the first or second aspect, wherein the first and second cylinder bores have the first and second cylinder bores. These axes are parallel to each other, and when viewed in the direction of the crankshaft, the distance between the axes of the one and other cylinder bores is smaller than the distance between the crankshafts.

  According to a fourth aspect of the present invention, in the third aspect, when the one-side and other-side cylinder bores are viewed in the crankshaft direction, the portions of the side walls of the one-side and other-side cylinder bores located on the counterpart crankshaft side are over. It is formed so that it wraps, and the bolt seat surface of the center head bolt is arranged in the overlapping portion when viewed in the cylinder bore axis direction.

  According to a fifth aspect of the present invention, in the third or fourth aspect, when the one-side and other-side cylinder bores are viewed in a direction perpendicular to the crankshaft, the end portions in the crankshaft direction of the side walls of the one-side and other-side cylinder bores are over. It is formed so that it wraps, and the bolt seat surface of the center head bolt is arranged in the overlapping portion when viewed in the cylinder bore axis direction.

  According to the first aspect of the present invention, among the head bolts for connecting the cylinder head and the cylinder block, the bolt seating surface of the center head bolt disposed between the one side and the other side cylinder bores is set to the one side and the other side. The bolt seat surface is located at a position farther from the mating surface of the cylinder block than the bolt seat surface of the side head bolt disposed on both sides of the side cylinder bore in the direction perpendicular to the crankshaft. Interference with a valve spring or the like can be avoided, and a space for arranging the center head bolt can be easily secured. Therefore, it is not necessary to increase the crankshaft direction interval or the crankshaft perpendicular direction interval between the one side and the other side cylinder bores.

  According to invention of Claim 2, while arrange | positioning a bolt seat surface between the spring seats in which the valve spring of an intake valve and an exhaust valve is arrange | positioned, in the position away from the said joint surface from this spring seat, That is, since it formed more upwards, it can avoid that a bolt seat surface interferes with a spring seat, As a result, it can prevent that an engine full length and full width become large.

  According to the third aspect of the present invention, since the bolt seat surface is disposed above the spring seat as described above, the distance between the axis lines of the one side and the other side cylinder bores is the crankshaft. It becomes possible to form it so that it may become narrower than the space | interval of mutual, and an engine full width can be narrowed reliably.

  According to the fourth aspect of the present invention, since the bolt seat surface is disposed above the spring seat as described above, when viewed in the cylinder bore axial direction, the one side is located on the opposite crankshaft side of the side wall of the other cylinder bore. It becomes possible to form the bolt seating surface of the center head bolt in the overlapping part between the parts, and the entire width of the engine can be surely reduced.

  In the invention of claim 5, since the bolt seat surface is disposed above the spring seat as described above, when viewed in the cylinder bore axial direction, the overlap between the crankshaft end portions of the side walls of the one side and the other side cylinder bores. It is possible to form the bolt seating surface of the center head bolt in the portion, and the total length of the engine can be surely shortened.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIGS. 1-6 is a figure for demonstrating the head bolt arrangement | positioning structure of an engine in 1st Embodiment of this invention.

In the figure, 1 is a water-cooled four-cycle 12-cylinder engine having three crankshafts. The engine 1 includes left and right cylinder portions 2a and 2b formed so as to form a symmetrical V bank, a cylinder block 2 having a crankcase portion 2c common to both cylinder portions, and the crankcase portion 2c. An oil pan 3 coupled to the lower mating surface 2d, and left and right cylinder heads 4, 5 coupled to the upper mating surfaces 2h, 2h of the left and right cylinder portions 2a, 2b with head bolts 37, 38; The left and right cylinder heads 4 and 5 have left and right head covers 6 and 7 mounted on the upper mating surfaces.

  Here, since the left and right cylinder portions 2a and 2b are symmetrical and have basically the same structure, the left cylinder portion 2a and the left cylinder head 4 will be mainly described below, and the right cylinder portion 2b, A description of the right cylinder head 5 will be added.

  The left cylinder portion 2a is formed with outer and inner (one side, other side) cylinder bores 9 and 8 positioned on the outer and inner sides of the V bank. As shown in FIG. 1, the inner and outer cylinder bores 8 and 9 are formed such that their cylinder bore axes 8a and 9a are parallel to each other. As a result, the inner and outer cylinder bores 8 and 9 of the left cylinder portion 2a and the inner and outer cylinder bores 8 and 9 of the right cylinder portion 2b form a predetermined bank angle (for example, 60 °).

  As shown in FIGS. 1 and 5, the inner cylinder bore 8 and the outer cylinder bore 9 are positioned on the left crankshaft (counter crankshaft) 11 side, which will be described later, on the side wall of the inner cylinder bore 8 when viewed in the crankshaft direction. And a portion j1 located on the side of the center crankshaft (mating crankshaft) 10 (to be described later) on the side wall of the outer cylinder bore 9 are arranged close to each other in the direction perpendicular to the crankshaft so as to overlap in the crankshaft direction.

  The inner cylinder bore 8 and the outer cylinder bore 9 are, when viewed in a direction perpendicular to the crankshaft and the cylinder bore axis, the crankshaft end portion k2 on the side wall of the inner cylinder bore 8 and the crankshaft end portion on the side wall of the outer cylinder bore 9. They are arranged close to each other in the crankshaft direction so that k1 overlap.

  Furthermore, the cylinder head side mating surface 2h of the inner cylinder bore 8 and the outer cylinder bore 9 is orthogonal to the axes 8a and 9a of the cylinder bores 8 and 9, and forms the same plane across the cylinder bores.

  The cylinder bores 8 and 9 are staggered so as to be alternately positioned in the crankshaft direction as shown in FIG. 5 when viewed in the direction of the cylinder bore axes 8a and 9a. Specifically, in the left cylinder portion 2a, from the rear side of the engine, the outer cylinder bore 9, the inner cylinder bore 8, the outer cylinder bore 9,... And the crankshaft interval t1, t2,. Arranged at intervals in the direction perpendicular to the axis. On the other hand, in the right cylinder portion 2b, from the rear side of the engine, the outer cylinder bore 9 ′, the inner cylinder bore 8 ′,... They are arranged at intervals. Further, the cylinder bores 8 and 9 of the left cylinder part 2a are displaced by t3 as a whole from the right cylinder part 2b to the engine front side.

  As described above, the outer cylinder bores 9 and 9 'of the left and right cylinder portions 2a and 2b are disposed at the rear end of the cylinder block 2 of the engine 1 of the present embodiment 1 so as to be located outside the V bank. The inner cylinder bores 8 and 8 'are disposed so as to be deviated forward from the rear end portion in the longitudinal direction of the engine and located inside the V bank. Therefore, a relatively wide space A is formed at the rear end portion of the cylinder block 2 as indicated by hatching in FIG. Although not shown, a driving force transmission mechanism that transmits the driving force to the camshaft using the space A is disposed.

  The engine 1 of the present embodiment is a three-crankshaft engine having a plurality of crankshafts, specifically, a center crankshaft 10 and left and right (one side, other side) crankshafts 11 and 12. The center crankshaft 10 is disposed in the center of the crankcase 2c of the cylinder block 2 in the engine width direction and perpendicular to the V bank bisector L. The left crankshaft 11 is disposed on the left side (one side) and below the central crankshaft 10, and the right crankshaft 12 is disposed on the right side (other side) and below the central crankshaft 10. The three crankshafts 10 to 12 are arranged so as to be parallel to each other and symmetrical. Accordingly, the central crankshaft 10 is located on the upper side, the left and right crankshafts 11 and 12 are located on the lower side, and a straight line connecting the axes of the crankshafts and the axis lines of the outer cylinder bores 9 and 9 '. 9a and 9a ′ form a W-shape, and the center crankshaft 10 and the axis lines 8a and 8a ′ of the inner cylinder bores 8 and 8 ′ form a V-shape.

  The outer cylinder bore 9 is offset by t5 from the plane B including the axis of the left crankshaft 11 or the right crankshaft 12 and parallel to the cylinder bore axis 9a to the inside of the V bank. The inner cylinder bore 8 is offset from the plane B ′ including the center of the central crankshaft 10 and parallel to the cylinder bore axis 8a by t6 to the outside of the V bank. Therefore, the interval t7 between the cylinder bores 8 and 9 is narrower by (t5 + t6) than the interval between the left and right crankshafts 11 and 12 and the central crankshaft 10.

  A left outer piston 13 disposed in the outer cylinder bore 9 of the left cylinder portion 2a is connected to the left crankshaft 11 by a left outer connecting rod 14. The left inner piston 15 disposed in the inner cylinder bore 8 of the left cylinder portion 2a is connected to the central crankshaft 10 by a left inner connecting rod 16. Similarly, the outer side of the right cylinder portion 2b, the right outer side and the inner pistons 13 'and 15' disposed in the inner cylinder bores 9 'and 8' are connected to the right crankshaft 12 by the outer and inner connecting rods 14 'and 16'. , Connected to the central crankshaft 10.

  Each of the crankshafts 10 to 12 is a bearing wall portion 2e formed so as to form a vertical wall in the crankcase portion 2c of the cylinder block 2, and a bearing wall portion 2e that is detachably fastened and fixed to the bearing wall portion 2e by a bolt 20. It is pivotally supported by the block 19. As shown in FIG. 6, the bearing wall 2e of the cylinder block 2 defines three crank chambers C1, C2, C3 having substantially the same size in the crankshaft direction in the crankcase portion 2c. Are arranged as follows. The lower end surface of each bearing wall 2e is flush with the lower mating surface 2d, and a recess having a boundary wall 2f extending in the vertical direction and a mating surface 2g extending in the lateral direction is formed in the middle. .

  The bearing block 19 is a rectangular thick plate, and is of an upper and lower divided type comprising upper and lower blocks 17 and 18. The end face 19a of the bearing block 19 in the direction perpendicular to the crankshaft is positioned in the direction perpendicular to the crankshaft by the boundary wall 2f.

  The central crankshaft 10 includes one relatively short front end journal portion 10a ′ corresponding to the thickness of the bearing wall 2e, three relatively long main journal portions 10a, and the front end side of each main journal portion 10. The three crank arm portions 10b are integrally formed with each other, and the crank pin portion 10c is integrally formed so as to connect the radially outer ends of the respective crank arm portions 10b. A counterweight portion 10b 'is formed on the opposite side of each crank arm portion 10b across the crank axis. Similarly, the left and right crankshafts 11 and 12 include one rear end journal portion 11a 'and 12a', three main journal portions 11a and 12a, crank arm portions 11b and 12b, and crank pin portions 11c and 12c. Counterweight portions 11b 'and 12b'.

  The front end journal portion 10a 'and the main journal portion 10a of the central crankshaft 10 are flat bearings by a bearing hole g formed between the upper mating surface 17b of the upper block 17 and the mating surface 2g of the bearing wall 2e. It is pivotally supported. Further, the rear end journal portions 11a 'and 12a' and the main journal portions 11a and 12a of the left and right crankshafts 11 and 12 are respectively provided with bearing holes h formed between the mating surfaces 17a and 18a of the upper and lower blocks 17 and 18. It is pivotally supported by i through a plain bearing.

  The front and rear journal portions 10a ', 11a', 12a 'of the crankshafts 10, 11, 12 and the bearing holes g, h, i that support the main journal portions 10a, 11a, 12a are viewed from above. Are supported by bearings arranged in a straight line in the direction perpendicular to the crankshaft.

  The crank arm portion 10b of the central crankshaft 10 is formed so as to be close to the front bearing wall portion 2e of the crank chambers C1, C2, C3. Large end portions 16a and 16a 'of the inner connecting rods 16 and 16' are arranged in parallel and connected to the crank pin portion 10c between the crank arm portions 10b and 10b so as to be adjacent to each other.

  The crank arm portion 11b of the left crankshaft 11 is disposed adjacent to the rear side in the crankshaft direction of the crank arm portion 10b of the central crankshaft 10, and a crank pin portion 11c between the crank arm portions 11b and 11b. The large end portion 14a of the outer stove 14 is connected to the main body. Similarly, the crank arm portion 12b of the right crankshaft 12 is disposed adjacent to the bearing wall portion 2e on the rear side of each of the crank chambers C1, C2, C3, and a crank pin portion between the crank arm portions 12b, 12b. A large end portion 14a 'of the outer connecting rod 14' is connected to 12c.

  The crankshaft direction interval between the outer connecting rod 14 connected to the left crankshaft 11 and the inner connecting rod 16 connected to the central crankshaft 10 is the same as the interval between the cylinder bores 9 and 8, t1, t2,. . Similarly, the crankshaft direction interval between the outer connecting rod 14 'connected to the right crankshaft 12 and the inner connecting rod 16' connected to the central crankshaft 10 is t1, which is the same as the interval between the cylinder bores 9 'and 8'. t2. The crankshaft direction interval between the large end portion 14a on the left crankshaft 11 side and the large end portion 14a 'on the right crankshaft 12 side is the same as the crankshaft direction interval between the large end portions 16a and 16a' on the central crankshaft 10 side. t3.

  Here, the central crankshaft 10 and the left and right crankshafts 11 and 12 are arranged as close to each other as possible in the direction perpendicular to the axis. That is, as shown in FIG. 1, a part of the rotation locus a passing through the outermost ends of the large ends 16a and 16a 'of the inner connecting rods 16 and 16' connected to the central crankshaft 10 is the left and right crankshafts. 11 and 12 and a part of the journal portions 11a and 12a, and the outermost ends of the large end portions 14a and 14a 'of the outer connecting rods 14 and 14' connected to the left and right crankshafts 11 and 12, respectively. The crankshafts 10 to 12 are arranged closer to each other so that a part of the passing rotation trajectories b and b overlaps a part of the journal portion 10 a of the central crankshaft 10.

  Each of the crankshafts 10 to 12 is provided with a relief portion for avoiding interference due to the overlap. Specifically, as shown in FIGS. 1 and 6, the outer connecting rod connected to the left and right crankshafts 11 and 12 of the main journal portion 10 a of the central crankshaft 10 in the crank chamber C1 on the rear end side. A central relief portion 10d is formed at a portion of the 14, 14 'facing the large end portions 14a, 14a'. A left relief portion 11d is formed in a portion of the main journal portion 11a of the left crankshaft 11 that faces the large end portions 16a and 16a 'of the inner connecting rods 16 and 16' connected to the central crankshaft 10. ing. Similarly, a right relief portion 12d is formed in a portion of the main journal portion 12a of the right crankshaft 12 facing the large end portions 16a and 16a 'of the inner connecting rods 16 and 16' connected to the central crankshaft 12. Is formed. The central relief portion 10d and the left and right relief portions 11d and 12d are set to have substantially the same axial length. A similar relief portion is also formed in the crank chambers C2 and C3.

  Here, each of the relief portions 10d, 11d, and 12d points to a portion left by removing a part of each main journal portion, and has a substantially fan shape when viewed in the crankshaft direction ( (See FIG. 1). Further, when the cut-out removed portion is viewed in the direction perpendicular to the crankshaft, the outer portion is substantially in line with the shapes of the large end portions 16a, 16a ', 14a, 14a' and the crank arm portions 10b to 12b that support the large end portions 16a, 16a ' It has a trapezoidal shape (see FIG. 6).

  These relief portions 10d to 12d are arranged so that the notch removal portion constituting the relief portion is located on the large end side when the large end portion of each connecting rod comes to an angular position closest to the counterpart crankshaft. In addition, the angular position is set. In other words, as the crankshafts 10 to 12 rotate, a part of the rotation trajectories a and a of the large ends 16a and 16a ′ of the inner connecting rods 16 and 16 ′ connected to the central crankshaft 10, The left and right relief shafts 11d and 12d of the left and right crankshafts 11 and 12 overlap with the left and right crankshafts 11 and 12 and overlap with the left and right crankshafts 11 and 12, respectively. The rotational phases of the crankshafts 10 to 12 are set so that a part of the rotation trajectories b and b of the end portions 14a and 14a 'and the central relief portion 10d of the central crankshaft 10 overlap in the crankshaft direction. Has been.

  The central crankshaft 10, the left crankshaft 11, and the right crankshaft 12 project rearward from the bearing wall 2e at the rear end of the crank chamber C1, and the bearing wall 2e is formed on each projecting portion. A central transmission gear 21, a left transmission gear 22, and a right transmission gear 23 are mounted so as to be close to the rear side surface. These transmission gears 21 to 23 are meshed with each other, and the power generated in the outer cylinder bores 9 and 9 is generated in the inner cylinder bores 8 and 8 from the left and right transmission gears 22 and 23 through the central transmission gear 21. The resultant power is output from the central crankshaft 10 to the rear of the engine in a combined state with the motive power. In the engine 1 of this embodiment, the central crankshaft 10 rotates clockwise as viewed from the rear of the engine, and the left and right crankshafts 11 and 12 rotate counterclockwise.

  Combustion recesses 4b and 5b are formed in portions facing the cylinder bores 8 and 9 of the cylinder bore side mating surfaces 4a and 5a of the left and right cylinder heads 4 and 5, respectively. The left combustion recess 4b The intake and exhaust valve holes 4e and 4f of the intake port 4c and the exhaust port 4d are opened. Similarly, intake and exhaust valve holes of the intake port 5c and the exhaust port 5d are opened in the right combustion recess 5b. A branch pipe 24a of the intake manifold 24 is connected to the external connection openings of the intake ports 4c and 5c. The surge tank 24b of the intake manifold 24 extends in the crankshaft direction on the upper surfaces of the head covers 6 and 7. ing. Furthermore, an exhaust manifold 25 is connected to the external connection openings of the exhaust ports 4d and 5d.

  An intake valve 26 and an exhaust valve 27 are disposed in the intake valve hole 4e and the exhaust valve hole 4f, respectively, so that they can be opened and closed. The intake valve 26 and the exhaust valve 27 are formed by the valve springs 26b and 27b interposed between the retainers 26a and 27a mounted on the upper ends of the intake valves 26 and the spring seats 2m and 2n formed on the cylinder head 4, respectively. Energized in the closing direction. Here, when the spring seat 2m for the intake valve 26 of the outer cylinder bore 9 and the spring seat 2n for the exhaust valve 27 of the adjacent inner cylinder bore 8 are viewed in the direction of the cylinder bore axes 9a and 8a, both the cylinder bores 9 , 8 are arranged so as to be located at the boundary portion of the side walls of the two and adjacent to each other. The spring seats 2m and 2n located above the boundary portion are located at a height near the upper joint surface 4e of the cylinder head 4.

  The intake valves 26 and 26 and the exhaust valves 27 and 27 are opened and closed by an intake cam shaft 28 and an exhaust cam shaft 29 via intake and exhaust rocker arms 28a and 29a. The intake camshaft 28 is shared by intake valves 26 and 26 arranged in parallel to each other for the outer and inner cylinder bores 9 and 8, and the exhaust camshaft 29 is similarly used for the outer and inner cylinder bores 9 and 8. Are shared by the exhaust valves 27, 27 arranged in parallel with each other.

  Here, the left and right cylinder heads 4 and 5 and the left and right cylinder portions 2a and 2b of the cylinder block 2 are coupled by a plurality of center head bolts 37 disposed around the cylinder bore and side head bolts 38. Has been. When viewed in the cylinder bore axial direction, the center head bolt 37 is located at the boundary j1 and j2 of the inner and outer cylinder bores 8 and 9 adjacent to each other in the direction perpendicular to the crankshaft, that is, at the boundary between the peripheral walls of both cylinder bores 8 and 9. It is arranged to be located. In other words, the center head bolt 37 is disposed so as to be positioned at portions k1 and k2 adjacent to the inner and outer cylinder bores 8 and 9 in the crankshaft direction when viewed in the cylinder bore axial direction. The side head bolts 38 are disposed so as to be located on both outer sides in the direction perpendicular to the crankshaft of the inner and outer cylinder bores with the center head bolt 37 interposed therebetween.

  A center bolt seat 39 for the center head bolt 37 is formed between the adjacent spring seat 2m for the intake valve 26 and the spring seat 2n for the exhaust valve 27 of the cylinder heads 4 and 5, and is viewed in the cylinder bore axial direction. At this time, the side bolt seats 40 for the side head bolts 38 are formed so as to be positioned on both outer sides in the direction perpendicular to the crankshaft of the inner and outer cylinder bores 8 and 9 with the center bolt seat 39 interposed therebetween. Both the center bolt seat 39 and the side bolt seat 40 have a cylindrical shape, and bolt seat surfaces 39a and 40a are counterbored at the upper end portions thereof, and bolt holes 39b and 40b are formed at the upper and lower portions of the shaft center. It is formed so as to penetrate through.

  The center head bolt 37 and the side head bolt 38 are inserted into the bolt holes 39b and 40b and screwed into the cylinder block, and the bolt heads of the head bolts 37 and 38 are fastened to the bolt seat surfaces 39a and 40a. ing.

  Here, the height of the bolt seat surface 40a of the side bolt seat 40 is the height from the lower joint surface 4a of the left cylinder head 4 or the upper joint surface 2h of the cylinder block 2 to the substantially ceiling surface of the exhaust port 4d and the intake port 4c. On the other hand, the height of the bolt seat surface 39a of the center bolt seat 39 is set to a height protruding above the spring seats 2m and 2n. That is, the bolt seat surface 39a of the center bolt seat 39 has a height higher than the bolt seat surface 40a of the side bolt seat 40 from the lower joint surface 4a of the cylinder head 4 or the upper joint surface 2h of the left cylinder portion 2a. Is formed.

  In the engine 1 of the present embodiment, the center head bolt 37 is disposed at the boundary between the inner and outer cylinder bores 8 and 9 arranged in a staggered manner, and the side head bolt 38 is disposed at both outer sides in the direction perpendicular to the crankshaft of both the cylinder bores 8 and 9. At this time, the bolt seat surface 39a of the center bolt seat 39 is positioned higher than the bolt seat surface 40a of the side bolt seat 40, specifically, slightly higher than the spring seats 2m and 2n for the intake valve 26 and the exhaust valve 27. Since it has been arranged, the bolt seat surface 39a of the center bolt seat 39 can be formed without cutting the seat surfaces of the spring seats 2m, 2n. As described above, since it is not necessary to increase the crankshaft direction interval of the cylinder bores 8 and 9 and the crankshaft perpendicular direction interval in order to secure the space for arranging the center head bolt 37, there is a problem that the total length and the entire width of the engine are increased. Can be avoided.

  Further, since it is not necessary to widen the cylinder bores 8 and 9 in the direction perpendicular to the crankshaft, the angle between the intake valve 26 and the exhaust valve 27 and the combustion chamber shape can be secured. The combustion chambers and piston shapes of the outer cylinder bores 8 and 9 can be set to be the same, and engine performance and exhaust gas properties can be improved. Further, since the bolt seat surface 39a is disposed above the spring seats 2m and 2n as described above, the inner and outer cylinder bores 8 and 9 are separated from each other by the interval between the axis lines 8a and 9a of the cylinder bores 8 and 9. It becomes possible to form it so that it may become narrower than the space | interval of 10,11, and an engine full width can be narrowed reliably.

  Furthermore, as described above, the bolt seat surface 39a is disposed above the spring seats 2m and 2n, so that the portions of the side walls of the inner and outer cylinder bores 8 and 9 in the crankshaft direction between the portions j2 and j1 located on the counterpart crankshaft side. The bolt seat surface 39a of the center head bolt 37 can be formed in the overlapping portion, and the entire engine width can be surely reduced.

  Since the bolt seat surface 39a is disposed above the spring seats 2m and 2n as described above, the crankshaft end portions k2 and k1 on the side walls of the inner and outer cylinder bores 8 and 9 overlap each other in the direction perpendicular to the crankshaft. The bolt seating surface 39a of the center head bolt 37 can be formed in the portion, and the overall length of the engine can be reliably shortened.

  Further, in the present embodiment, the large end portion 16a of the inner connecting rod 16 of the central crankshaft 10 is positioned between the journal portions 11a and 11a of the left crankshaft 11 and between the journal portions 12a and 12a of the right crankshaft 12, Since the relief portions 11d and 12d are formed between the journal portions of the left and right crankshafts 11 and 12, and the relief portion 10d is similarly formed on the central crankshaft 10, the central crankshaft 10, the left and right crankshafts 11, 12 can be arranged as close as possible to the maximum, the engine displacement can be increased and the engine output can be increased while the engine width can be made compact.

  Here, in the first embodiment, the case of the three-crankshaft engine including the cylinder block 2 having the left and right cylinder portions 2a and 2b and the three crankshafts 10 to 12 has been described. Is also applicable to the engine of the second embodiment having one cylinder part and two crankshafts.

  Specifically, the engine of the second embodiment has a configuration in which, for example, the right cylinder portion 2b, pistons 13 'and 15', connecting rods 14 'and 16', and the right crankshaft 12 are removed in FIG. .

  Also in the second embodiment, by setting the bolt seat surface 39a of the center head bolt 37 higher than the bolt seat surface 40a of the side head bolt 38, the center bolt seat can be cut without cutting the seat surfaces of the spring seats 2m and 2n. The bolt seating surface 39a can be formed, and it is not necessary to increase the crankshaft direction spacing of the cylinder bores 8 and 9 and the crankshaft perpendicular spacing in order to secure the space for placing the center head bolt 37. Can be avoided. Furthermore, the same effect as the first embodiment can be obtained.

1 is a cross-sectional rear view of a three crankshaft engine according to a first embodiment of the present invention. It is a cross-sectional back view of the left cylinder part of the said embodiment engine. FIG. 5 is a cross-sectional rear view (a cross-sectional rear view taken along line III-III in FIG. 4) of the left cylinder head of the engine according to the embodiment. It is a top view in the state where the head cover of the left cylinder head of the above-mentioned embodiment engine was removed. . It is the top view seen in the cylinder bore axial direction of the cylinder block of the engine of the above-mentioned embodiment. It is a top view which shows the arrangement | positioning state of the crankshaft of the said embodiment engine.

Explanation of symbols

1 Engine 2 Cylinder blocks 2h, 4a Interfacing surfaces 2m, 2n Spring seats 8, 9 Cylinder bores 8a, 9a Cylinder bore axes 10-12 Crankshafts 26, 27 Intake valves, exhaust valves 26a, 27a Valve spring 37 Center head bolt 38 Side head bolt 39a Center head bolt bolt seating surface 40a Side bed bolt bolt seating surface j1, j2 Parts k1, k2 of the cylinder bore side wall located on the opposite crankshaft side Crank axis end of the cylinder bore side wall portion

Claims (5)

In an engine comprising a cylinder block having a plurality of one-side and other-side cylinder bores arranged in a staggered manner so as to be alternately positioned in the crankshaft direction, and a cylinder head coupled to a mating surface of the cylinder block with a head bolt,
The head bolt includes a center head bolt disposed between the one and other cylinder bores adjacent to each other in a direction perpendicular to the crankshaft, and a direction perpendicular to the crankshaft of the one and other cylinder bores sandwiching the center head bolt. And a bolt seat surface to which the center head bolt is fastened is formed at a position farther from the mating surface than a bolt seat surface to which the side bed bolt is fastened. An engine characterized by   2. The center head bolt according to claim 1, wherein the center head bolt is disposed between spring seats in which valve springs of the one side and other side cylinder bore intake valves and exhaust valves adjacent to each other in the direction perpendicular to the crankshaft are arranged. The engine characterized in that the bolt seat surface of the head bolt is formed at a position farther from the mating surface than the spring seat.   In Claim 1 or 2, the one side, one side for the other side cylinder bore, the other side crankshaft, the axis of the one side, the other side cylinder bore is parallel to each other, The engine is characterized in that when viewed in the direction of the crankshaft, the distance between the axes of the one-side and other-side cylinder bores is narrower than the distance between the crankshafts.   In Claim 3, the one-side and other-side cylinder bores are formed so that the portions located on the counterpart crankshaft side of the side walls of the one-side and other-side cylinder bores overlap when viewed in the crankshaft direction. The engine is characterized in that the bolt seat surface of the center head bolt is disposed in the overlapping portion when viewed in the cylinder bore axis direction.   In Claim 3 or 4, the said one side and other side cylinder bore are formed so that the crankshaft direction edge part of the side wall of this one side and other side cylinder bore may overlap, when it sees in the direction orthogonal to a crankshaft. The engine is characterized in that the bolt seat surface of the center head bolt is disposed in the overlapping portion when viewed in the cylinder bore axis direction.

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