JP2019070364A - Cylinder block for v-shaped multicylinder internal combustion engine - Google Patents

Abstract

To attain downsizing while attaining reduction of a pumping loss.SOLUTION: A penetration hole 50 is formed in an inter-bank region 19 on each of partition walls 14 and disposed at an opposite side of a first cylinder bore 22 with respect to an axial line L1 of a first female screw hole 21h and at an opposite side of a second cylinder bore 32 with respect to an axial line L2 of a second female screw hole 31h. Therefore, the first cylinder bore 22, the second cylinder bore 32 and a crankshaft 12 can be made close. In comparison with a case where the penetration hole 50 is formed at a position across axial lines of a first bolt 41a and a second bold 42a with respect to each of the partition walls 14, concentration of a stress in a portion that is positioned in a direction orthogonal with a stroke direction of a first piston 23 and a second piston 33 is suppressed on an inner peripheral surface of the penetration hole 50.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a cylinder block of a V-type multi-cylinder internal combustion engine.

  Generally, a cylinder block of a V-type multi-cylinder internal combustion engine has a first bank and a second bank arranged in a V-type. A plurality of cylinder bores are formed in the first bank and the second bank, respectively, in the axial direction of the crankshaft. Pistons are accommodated in respective cylinder bores so as to be capable of reciprocating motion. The cylinder block communicates with one cylinder bore of each of the first and second banks and supports a plurality of crank chambers arranged in the axial direction of the crankshaft, rotatably supports the crankshaft, and the axial direction of the crankshaft And a partition separating the adjacent crank chambers. In each crank chamber, a pressure fluctuation occurs because the volume changes as the piston reciprocates in each cylinder bore. The pressure fluctuation in the crank chamber causes an increase in resistance during operation of the V-type multi-cylinder internal combustion engine, so-called pumping loss.

  Therefore, for example, in Patent Document 1, through holes (breathing holes) are formed in each partition wall, and adjacent crank chambers in the axial direction of the crankshaft are communicated with each other through the through holes. According to this, since air can be transferred through the through holes in the adjacent crank chambers in the axial direction of the crankshaft, the pressure fluctuation in each crank chamber is alleviated and the pumping loss is reduced.

JP, 2009-275539, A

  The cylinder heads are attached to the first and second banks by bolts, respectively. Here, when the axial direction of each bolt coincides with the stroke direction of the piston reciprocating in each cylinder bore, a load acts on the cylinder block in the stroke direction of the piston as the piston reciprocates. Then, for example, when the through hole is formed at a position intersecting the axis of each bolt with respect to each partition, stress is applied to a portion located in the direction orthogonal to the stroke direction of the piston on the inner peripheral surface of the through hole. Are easy to concentrate. When stress concentrates on a portion of the inner circumferential surface of the through hole located in a direction orthogonal to the stroke direction of the piston, the through hole is deformed, and air is passed through the through holes in adjacent crank chambers in the axial direction of the crankshaft. It becomes difficult to reduce the pumping loss.

  It is also considered to miniaturize the cylinder block by bringing the cylinder bores of the first and second banks into close proximity with the crankshaft. For example, in Patent Document 1, one through hole is formed for each partition between the cylinder bores of the first and second banks and the crankshaft. In such a case, the cylinder bores of the first and second banks can not be brought close to the crankshaft by the amount of the through holes, and the cylinder block can not be miniaturized. The

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a cylinder block of a V-type multi-cylinder internal combustion engine capable of achieving downsizing while reducing pumping loss. It is.

  The cylinder block of the V-type multi-cylinder internal combustion engine which solves the above-mentioned subject is formed in the 1st bank and the 2nd bank which are arranged in V type, and the 1st bank, and is arranged in multiple in the axial direction of the crankshaft. A first cylinder bore, a plurality of second cylinder bores formed in the second bank and arranged in the axial direction of the crankshaft, one of the plurality of first cylinder bores, and the plurality of second cylinder bores A plurality of crank chambers communicating with one of the plurality of crank chambers and arranged in the axial direction of the crankshaft; a partition rotatably supporting the crankshaft and separating the adjacent crank chambers in the axial direction of the crankshaft; The crank chamber is formed in each of the partition walls and adjacent to each other in the axial direction of the crankshaft. And a first female screw hole formed around the first cylinder bore in the first bank and in which a first bolt for attaching a first cylinder head to the first bank is screwed, and And a second female screw hole formed around the second cylinder bore in the second bank and in which a second bolt for mounting a second cylinder head is screwed into the second bank, the first female screw hole And the axis of the second female screw hole corresponds to the direction of the stroke of the second piston reciprocating in the second cylinder bore, and the axis of the second female screw hole corresponds to the stroke direction of the first piston reciprocating in the first cylinder bore. A cylinder block of a V-type multi-cylinder internal combustion engine, wherein the through holes connect the first bank and the second bank in each of the partition walls. The first female screw formed in an inter-bank region provided between the first bank and the second bank, and formed on the inter-bank region side around the first cylinder bore in the first bank The axis of the second female screw hole, which is formed on the side of the inter-bank region around the second cylinder bore in the second bank opposite to the first cylinder bore with respect to the axis of the hole. Two cylinder bores are disposed on the opposite side.

  According to this, the through hole is formed in the region between the banks in each partition, and the side opposite to the first cylinder bore with respect to the axis of the first female screw and the first with respect to the axis of the second female screw Since the two cylinder bores are disposed on the opposite side, the first cylinder bore and the second cylinder bore can be brought close to the crankshaft. Therefore, the cylinder block can be miniaturized. Further, the first piston and the second piston are formed on the inner circumferential surface of the through hole in comparison with the case where the through hole is formed at a position intersecting the axis of the first bolt and the axis of the second bolt with respect to each partition. It is possible to suppress concentration of stress on a portion located in a direction orthogonal to the stroke direction of the piston. As a result, in the inner peripheral surface of the through hole, stress concentrates on a portion located in a direction orthogonal to the stroke direction of the first piston and the second piston, so that the through hole is deformed and adjacent in the axial direction of the crankshaft. It is possible to suppress that it is difficult for air to travel through the through holes in the corresponding crank chamber. From the above, it is possible to miniaturize the cylinder block while reducing the pumping loss.

  In the cylinder block of the V-type multi-cylinder internal combustion engine, an inner circumferential surface of the through hole is a first conical surface whose diameter increases as it approaches one of the adjacent crank chambers in the axial direction of the crankshaft; It is preferable to have a second conical surface whose diameter increases as it approaches the other of the adjacent crank chambers in the axial direction of the crankshaft.

  According to this, the air can easily move back and forth through the through holes in the adjacent crank chambers in the axial direction of the crankshaft, so that the pressure fluctuation in each crank chamber can be easily alleviated, and the pumping loss can be reduced efficiently. It can be carried out.

  In the cylinder block of the V-type multi-cylinder internal combustion engine, an inner circumferential surface of the through hole is formed by a first straight portion extending along an axis of the first female screw and a first straight portion extending along an axis of the second female screw. It is preferable to have two straight portions.

  According to this, in the inner peripheral surface of the through hole, it is possible to further easily suppress concentration of stress on a portion located in a direction orthogonal to the stroke direction of the first piston and the second piston.

  According to the present invention, downsizing can be achieved while reducing pumping loss.

BRIEF DESCRIPTION OF THE DRAWINGS Sectional drawing which shows V-type multi-cylinder internal combustion engine in embodiment. The top view of a cylinder block. Line 3-3 in FIG. 1 sectional drawing. FIG. 4 is a cross-sectional view taken along line 4-4 in FIG. The expanded sectional view of a cylinder block. The expanded sectional view of the cylinder block in another embodiment. The expanded sectional view of the cylinder block in another embodiment.

Hereinafter, an embodiment in which a cylinder block of a V-type multi-cylinder internal combustion engine is embodied will be described according to FIGS. 1 to 5. The V-type multi-cylinder internal combustion engine of the present embodiment is mounted on a vehicle.
As shown in FIG. 1, the V-type multi-cylinder internal combustion engine 10 includes a cylinder block 11. The cylinder block 11 has a main body portion 20, and a first bank 21 and a second bank 31 which are branched and extended with respect to the main body portion 20 and arranged in a V shape. The crankshaft 12 is accommodated in the main body 20.

  As shown in FIG. 2, four first cylinder bores 22 are formed in the first bank 21. The four first cylinder bores 22 are arranged in the axial direction of the crankshaft 12 (the direction indicated by the arrow X1 in FIG. 2). Therefore, the cylinder block 11 has the first cylinder bores 22 formed in the first bank 21 and arranged in plural in the axial direction of the crankshaft 12.

  Four second cylinder bores 32 are formed in the second bank 31. The four second cylinder bores 32 are arranged in the axial direction of the crankshaft 12. Thus, the cylinder block 11 has the second cylinder bores 32 formed in the second bank 31 and arranged in plural in the axial direction of the crankshaft 12. The V-type multi-cylinder internal combustion engine 10 of the present embodiment is a V-type 8-cylinder diesel engine.

  As shown in FIG. 1, the open end 22 e on the crankshaft 12 side of the first cylinder bore 22 opens toward the crankshaft 12. The first pistons 23 are accommodated in the respective first cylinder bores 22 of the first bank 21 so as to be capable of reciprocating. Each first piston 23 is connected to the crankshaft 12 via a connecting rod 24. Then, the reciprocating motion of each first piston 23 is converted to the rotational motion of the crankshaft 12 by the connecting rod 24.

  Further, an open end 32 e on the crankshaft 12 side of the second cylinder bore 32 opens toward the crankshaft 12. The second pistons 33 are accommodated in the respective second cylinder bores 32 of the second bank 31 so as to be capable of reciprocating. Each second piston 33 is connected to the crankshaft 12 via a connecting rod 34. Then, the reciprocating motion of each second piston 33 is converted to the rotational motion of the crankshaft 12 by the connecting rod 34.

  As shown in FIG. 1 and FIG. 3, the cylinder block 11 communicates with one of the plurality of first cylinder bores 22 and one of the plurality of second cylinder bores 32 and has a plurality of cylinder blocks 11 in the axial direction of the crankshaft 12. It has a crank chamber 13 arranged. Each crank chamber 13 is formed inside the main body 20. In the crank chamber 13, a crank pin 12a and a balance weight 12b of the crankshaft 12 are disposed.

  As shown in FIG. 3, the cylinder block 11 has a partition 14 that rotatably supports the crankshaft 12 and that separates adjacent crank chambers 13 in the axial direction of the crankshaft 12. On the lower surface of each partition 14, a bearing surface 14 a rotatably supporting the crankshaft 12 is formed. As shown in FIG. 1, the bearing surface 14 a is recessed from the lower surface of each partition 14 in a semicircular shape along the outer peripheral surface of the crankshaft 12.

  Crank caps 15 are attached to the lower surfaces of the bulkheads 14 respectively. The crank cap 15 is attached to the lower surface of each partition 14 by an attachment bolt 16, for example. A plurality of bearing surfaces 15 a rotatably supporting the crankshaft 12 are formed on the surface of the crank cap 15 on the side of each partition wall 14. The bearing surface 15 a is semicircular along the outer peripheral surface of the crankshaft 12 with respect to the surface on the partition wall 14 side of the crank cap 15. Each bearing surface 15 a rotatably supports the crankshaft 12 in cooperation with the bearing surface 14 a of each partition 14.

  An oil pan 17 is attached to the main body portion 20 of the cylinder block 11. The oil pan 17 is attached to an end surface (lower surface) opposite to the first bank 21 and the second bank 31 with respect to the main body 20. Each crank chamber 13 communicates with the inside of the oil pan 17. The inside of the oil pan 17 communicates the crank chambers 13 adjacent to each other in the axial direction of the crankshaft 12. Engine oil is stored in the oil pan 17. In the state where the oil pan 17 is filled with engine oil, the air in the crank chamber 13 adjacent in the axial direction of the crankshaft 12 is less likely to travel due to the presence of the engine oil.

  The first bank 21 has a first bank inclined surface 21 a extending from the main body 20 and located on the second bank 31 side. The second bank 31 has a second bank inclined surface 31 a extending from the main body 20 and located on the first bank 21 side. The main body portion 20 has a valley surface 20a connecting the first bank inclined surface 21a and the second bank inclined surface 31a. Then, an imaginary straight line L10 connecting the edge of the first bank slope 21a opposite to the valley 20a and the edge of the second bank slope 31a opposite to the valley 20a, the first bank slope 21a A space surrounded by the second bank inclined surface 31 a and the valley surface 20 a is an inter-bank 18 between the first bank 21 and the second bank 31.

  Each partition wall 14 has an inter-bank area 19 provided between the first bank 21 and the second bank 31 connecting the first bank 21 and the second bank 31. Here, a straight line passing in the axial direction of the first cylinder bore 22 in a portion closest to the bank 18 in the inner circumferential surface of the first cylinder bore 22 is defined as a first imaginary straight line L11. A straight line passing the portion closest to 18 in the axial direction of the second cylinder bore 32 is taken as a second imaginary straight line L12. At this time, in the cross sectional view in FIG. 1, the inter-bank area 19 is an area located closer to the inter-bank 18 side than the first virtual straight line L11 and the second virtual straight line L12 in the partition 14.

  The V-type multi-cylinder internal combustion engine 10 has a first cylinder head 41 attached to the first bank 21. The first cylinder head 41 is attached to an end surface of the first bank 21 opposite to the main body 20 by a first bolt 41 a. The first cylinder head 41 closes an opening of the first cylinder bore 22 opposite to the crankshaft 12.

  A first female screw hole 21 h is formed around the first cylinder bore 22 in the first bank 21. A first bolt 41a for attaching the first cylinder head 41 to the first bank 21 is screwed into the first female screw hole 21h. The first female screw hole 21 h is formed on the inter-bank region 19 side around the first cylinder bore 22 in the first bank 21. The first female screw hole 21 h is formed in the first bank 21 at a portion adjacent to the first bank inclined surface 21 a. Therefore, the first female screw hole 21 h is formed at a portion near the inter-bank 18 in the first bank 21. The axis L1 of the first female screw hole 21h coincides with the stroke direction of the first piston 23 that reciprocates in the first cylinder bore 22. The axis L1 of the first female screw hole 21h coincides with the axis of the first bolt 41a. Thus, the axial direction of the first bolt 41 a coincides with the stroke direction of the first piston 23.

  The V-type multi-cylinder internal combustion engine 10 includes a second cylinder head 42 attached to the second bank 31. The second cylinder head 42 is attached to an end surface of the second bank 31 opposite to the main body 20 by a second bolt 42 a. The second cylinder head 42 closes the opening of the second cylinder bore 32 opposite to the crankshaft 12.

  A second female screw hole 31 h is formed around the second cylinder bore 32 in the second bank 31. A second bolt 42a for attaching the second cylinder head 42 to the second bank 31 is screwed into the second female screw hole 31h. The second female screw hole 31 h is formed on the side of the inter-bank region 19 around the second cylinder bore 32 in the second bank 31. The second female screw hole 31 h is formed in the second bank 31 at a portion adjacent to the second bank inclined surface 31 a. Therefore, the second female screw hole 31 h is formed in a portion closer to the space 18 between the banks in the second bank 31. The axis L2 of the second female screw hole 31h coincides with the stroke direction of the second piston 33 that reciprocates in the second cylinder bore 32. The axis L2 of the second female screw hole 31h coincides with the axis of the second bolt 42a. Therefore, the axial direction of the second bolt 42 a coincides with the stroke direction of the second piston 33.

  As shown in FIG. 4, in each partition wall 14, a circular through hole 50 is formed, which connects the adjacent crank chambers 13 in the axial direction of the crankshaft 12. Each through hole 50 allows air to move in and out of the adjacent crank chamber 13 in the axial direction of the crankshaft 12.

  The inner circumferential surface of each through hole 50 has a first conical surface 51 whose diameter increases as it approaches one of the adjacent crank chambers 13 in the axial direction of the crankshaft 12, and a crank chamber adjacent in the axial direction of the crankshaft 12 And a second conical surface 52 expanding in diameter toward the other of 13.

  The inner diameter of the opening edge on one side of the crank chamber 13 adjacent in the axial direction of the crankshaft 12 in the first conical surface 51 and the other side of the crank chamber 13 adjacent in the axial direction of the crankshaft 12 in the second conical surface 52 The inner diameter of the opening edge is the same. The edge of the first conical surface 51 opposite to one end of the crank chamber 13 adjacent in the axial direction of the crankshaft 12 and the other edge of the second conical surface 52 adjacent in the axial direction of the crankshaft 12 with the other crank chamber 13 Is connected to the opposite edge.

  The edge of the first conical surface 51 opposite to one end of the crank chamber 13 adjacent in the axial direction of the crankshaft 12 and the other edge of the second conical surface 52 adjacent in the axial direction of the crankshaft 12 with the other crank chamber 13 The connection portion with the opposite end edge is the portion with the smallest inner diameter in the inner peripheral surface of the through hole 50.

  As shown in FIG. 5, each through hole 50 is formed in the inter-bank region 19 in each partition 14 and is opposite to the first cylinder bore 22 with respect to the axis L1 of the first female screw hole 21h. The second cylinder bore 32 is disposed on the opposite side of the axis L2 of the two female screw holes 31h. Each through hole 50 is closer to the inter-bank 18 than the open end 22e of the first cylinder bore 22 and the open end 32e of the second cylinder bore 32, and the axis L1 of the first female screw hole 21h and the second female screw hole 31h It is disposed near the inter-bank 18 with respect to the axis L2. Therefore, each through hole 50 is formed at a position deviated from the axis of the first bolt 41 a and the axis of the second bolt 42 a with respect to each partition 14. The inner peripheral surface of the through hole 50 is spaced closer to the bank 18 with respect to the axis L1 of the first female screw hole 21h and the axis of the second female screw hole 31h.

Next, the operation of the present embodiment will be described.
In each crank chamber 13, a pressure fluctuation occurs because the volume changes due to the reciprocation of the first piston 23 in the first cylinder bore 22 and the reciprocation of the second piston 33 in the second cylinder bore 32. At this time, since the movement of air through each through hole 50 in the crank chamber 13 adjacent in the axial direction of the crankshaft 12 is permitted, the pressure fluctuation in each crank chamber 13 is alleviated, and the V-type multi-cylinder The resistance during operation of the internal combustion engine 10, so-called pumping loss, is reduced.

  When the axial direction of the first bolt 41 a and the second bolt 42 a coincides with the stroke direction of the first piston 23 and the second piston 33, the cylinder block 11 reciprocates the first piston 23 and the second piston 33. A load acts on the stroke direction of the 1st piston 23 and the 2nd piston 33 with movement. At this time, the through hole 50 is formed in the inter-bank region 19 in each partition wall 14, and the side opposite to the first cylinder bore 22 with respect to the axis L1 of the first female screw hole 21h and the second female screw hole 31h It is disposed on the opposite side to the second cylinder bore 32 with respect to the axis L2, and is offset from the axis of the first bolt 41a and the axis of the second bolt 42a. Therefore, compared with the case where the through hole 50 is formed at a position where the axis of the first bolt 41 a and the axis of the second bolt 42 a cross each partition 14, the inner circumferential surface of the through hole 50 It is suppressed that stress concentrates on the part located in the direction orthogonal to the stroke direction of 1 piston 23 and the 2nd piston 33.

The following effects can be obtained in the above embodiment.
(1) The through hole 50 is formed in the inter-bank region 19 in each partition wall 14 and on the opposite side to the first cylinder bore 22 with respect to the axis L1 of the first female screw hole 21h and in the second female screw hole 31h. It is arranged on the opposite side to the second cylinder bore 32 with respect to the axis L2. Therefore, the first cylinder bore 22 and the second cylinder bore 32 can be brought close to the crankshaft 12, and the cylinder block 11 can be miniaturized. Further, compared to the case where the through hole 50 is formed at a position where the axis of the first bolt 41 a and the axis of the second bolt 42 a intersect each partition 14, the inner circumferential surface of the through hole 50 It is suppressed that stress concentrates on the part located in the direction orthogonal to the stroke direction of 1 piston 23 and the 2nd piston 33. As a result, in the inner peripheral surface of the through hole 50, stress concentrates on a portion located in a direction orthogonal to the stroke direction of the first piston 23 and the second piston 33, whereby the through hole 50 is deformed. It is possible to suppress the difficulty of air coming and going through the through holes 50 in the crank chamber 13 adjacent in the axial direction of the above. From the above, it is possible to miniaturize the cylinder block 11 while reducing the pumping loss.

  (2) The inner circumferential surface of each through hole 50 is adjacent in the axial direction of the crankshaft 12 to the first conical surface 51 whose diameter increases as it approaches one of the adjacent crank chambers 13 in the axial direction of the crankshaft 12 And a second conical surface 52 whose diameter increases as it approaches the other of the corresponding crank chamber 13. According to this, the air can easily move back and forth through the through holes 50 in the crank chamber 13 adjacent to each other in the axial direction of the crankshaft 12, so that the pressure fluctuation in each crank chamber 13 can be easily alleviated and pumping Loss can be reduced efficiently.

The above embodiment may be modified as follows.
As shown in FIG. 6, the inner circumferential surface of the through hole 60 extends along the axis L1 of the first female screw hole 21h, and the second linear portion 61 extends along the axis L2 of the second female screw hole 31h. It may have a straight portion 62. The through hole 60 has a substantially home base shape when viewed from the axial direction of the crankshaft 12.

  An inner circumferential surface of the through hole 60 connects the extending portion 63 extending along the valley surface 20 a of the main body portion 20, the end edge of the extending portion 63 on the first bank 21 side, and the first straight portion 61. A bank side corner 64 and a second bank side corner 65 connecting the end of the extension 63 on the second bank 31 side and the second straight side 62 are provided.

  The first bank side corner portion 64 is a curved surface which gradually separates from the axis L1 of the first female screw hole 21h as it is separated from the first straight portion 61. The first bank side corner 64 is a curved surface that is convex toward the first bank 21. The end of the first bank side corner 64 on the extending portion 63 side is a portion of the first bank side corner 64 that is most separated from the axis L1 of the first female screw hole 21 h. The end of the first bank side corner 64 on the extending portion 63 side is a portion with the largest curvature in the first bank side corner 64.

  The second bank side corner portion 65 is a curved surface which is gradually separated from the axis L2 of the second female screw hole 31h as it is separated from the second straight portion 62. The second bank side corner 65 is a curved surface that is convex toward the second bank 31. The end of the second bank side corner 65 on the extension 63 side is a portion of the second bank side corner 65 that is most separated from the axis L2 of the second female screw hole 31 h. The end on the extension 63 side of the second bank side corner 65 is a portion with the largest curvature at the second bank side corner 65.

  Furthermore, the inner peripheral surface of the through hole 60 has an end opposite to the first bank side corner 64 in the first straight side 61 and an opposite side to the second bank side corner 65 in the second straight side 62. It has the connecting part 66 which connects with the edge. The connecting portion 66 is an arc-curved surface which is convex toward the crankshaft 12. The curvature of the connecting portion 66 is smaller than the curvature of the end of the first bank side corner 64 on the extension 63 side and the end of the second bank side corner 65 on the extension 63 side.

  The inner circumferential surface of the through hole 60 has a first straight portion 61 extending along the axis L1 of the first female screw hole 21h, and a second straight portion 62 extending along the axis L2 of the second female screw hole 31h. Therefore, in the inner peripheral surface of the through hole 60, concentration of stress on a portion located in a direction orthogonal to the stroke direction of the first piston 23 and the second piston 33 can be further suppressed easily.

  The end on the extension 63 side of the first bank side corner 64 is the portion with the largest curvature in the first bank side corner 64, and the end on the extension 63 side of the second bank side corner 65 Is the portion with the largest curvature in the second bank side corner 65. However, the end on the extension 63 side of the first bank side corner 64 is the most distant from the axis L 1 of the first female screw hole 21 h at the first bank side corner 64, and the second bank side corner 65 The end on the side of the extension portion 63 in the second bank side corner portion 65 is most separated from the axis L2 of the second female screw hole 31h. Therefore, even if a load is applied to the cylinder block 11 in the stroke direction of the first piston 23 and the second piston 33, the end on the side of the extension portion 63 in the first bank side corner 64 and the second bank side corner It is suppressed that stress is concentrated at the end on the side of the extending portion 63 in the portion 65.

  As shown in FIG. 7, the through hole 70 may have an elliptical hole shape as viewed from the axial direction of the crankshaft 12. The through hole 70 is formed in the partition wall 14 so that the longitudinal direction of the through hole 70 extends in a direction orthogonal to the valley surface 20 a of the main body 20 when viewed in the axial direction of the crankshaft 12. Therefore, the through hole 70 is formed in the partition wall 14 so that the short side direction of the through hole 70 extends parallel to the valley surface 20 a of the main body 20 when viewed from the axial direction of the crankshaft 12. The inner circumferential surface of the through hole 70 is spaced closer to the bank 18 than the axis L1 of the first female screw hole 21h and the axis L2 of the second female screw hole 31h.

  In the embodiment, the through hole 50 may be a rectangular shape, a triangular shape, or a polygonal shape such as a trapezoidal shape as viewed from the axial direction of the crankshaft 12. The through hole 50 may be viewed from the axial direction of the crankshaft 12 in the through hole 50. The shape is not particularly limited.

  In the embodiment, the arrangement position of the through hole 50 may be appropriately shifted according to the formation position of the oil hole for supplying the oil to the bearing surfaces 14 a and 15 a which are the sliding portions of the crankshaft 12. The point is that the through holes 50 are formed in the inter-bank region 19 in each partition 14 and the side opposite to the first cylinder bore 22 with respect to the axis L1 of the first female screw hole 21h and the second female screw hole 31h It may be disposed on the side opposite to the second cylinder bore 32 with respect to the axis L2.

  In the embodiment, the V-type multi-cylinder internal combustion engine 10 may have a configuration in which a balance shaft is inserted through the through hole 50, for example. The balance shaft receives the rotation of the crankshaft 12 and rotates at the same rotational speed as the crankshaft 12. When the balance shaft is inserted into the through hole 50, the outer diameter of the portion of the balance shaft located in the through hole 50 is smaller than the outer diameter of the portion of the balance shaft protruding from the through hole 50. Is preferred. According to this, the inside of the through hole 50 is passed as compared with the case where the outer diameter of the portion positioned in the through hole 50 in the balance shaft and the outer diameter of the portion protruding from the through hole 50 in the balance shaft The flow passage area of air can be secured.

  In the embodiment, the opening edge on one side of the crank chamber 13 adjacent in the axial direction of the crankshaft 12 in the first conical surface 51 and the crank chamber 13 adjacent in the axial direction of the crankshaft 12 in the second conical surface 52 The opening edge on the other side may be chamfered. According to this, the opening edge of one side of the crank chamber 13 adjacent in the axial direction of the crankshaft 12 in the first conical surface 51 and the crank chamber 13 adjacent in the axial direction of the crankshaft 12 in the second conical surface 52 As compared with the case where the opening edge on the other side has a pin angle, the air flow is less likely to be disturbed. As a result, air can easily travel through the through holes 50 in the adjacent crank chambers 13 in the axial direction of the crankshaft 12, so pressure fluctuations in the crank chambers 13 can be easily alleviated, and pumping loss The reduction can be performed efficiently.

  In the embodiment, even if the first female screw hole 21 h is formed in the portion on the oil pan 17 side opposite to the first bank inclined surface 21 a around the first cylinder bore 22 in the first bank 21. Good.

  In the embodiment, even if the second female screw hole 31 h is formed also in a portion on the oil pan 17 side opposite to the second bank inclined surface 31 a around the second cylinder bore 32 in the second bank 31. Good.

  In the embodiment, the inner circumferential surface of the through hole 50 has an end edge of the first conical surface 51 opposite to one of the adjacent crank chambers 13 in the axial direction of the crankshaft 12 and a crank at the second conical surface 52 It may have a surface connecting between the other end of the adjacent crank chamber 13 in the axial direction of the shaft 12 and the end edge opposite to the other.

In the embodiment, the inner circumferential surface of the through hole 50 may not have the first conical surface 51 and the second conical surface 52, and the entire inner circumferential surface may extend in the axial direction of the crankshaft 12.
In the embodiment, the number of first cylinder bores 22 of the first bank 21 and the number of second cylinder bores 32 of the second bank 31 are not particularly limited. For example, the first cylinder bore 22 and the second cylinder bore 32 The number may be three each. Thus, the V-type multi-cylinder internal combustion engine 10 may be a V-type six-cylinder diesel engine.

  In the embodiment, the V-type multi-cylinder internal combustion engine 10 may be other than a diesel engine, for example, a gasoline engine.

  DESCRIPTION OF SYMBOLS 10 ... V-type multi-cylinder internal combustion engine, 11 ... cylinder block, 12 ... crankshaft, 13 ... crank chamber, 14 ... partition wall, 19 ... area between banks, 21 ... 1st bank, 21h ... 1st female screw hole, 22 ... 1st 1 cylinder bore 23 23 first piston 31 second bank 31 h second female screw hole 32 second cylinder bore 33 second piston 41 first cylinder head 41 a first bolt 41 second 2 cylinder head 42a: second bolt 50, 60, 70: through hole 51: first conical surface 52: second conical surface 61: first straight part 62: second straight part

Claims (3)

First and second banks arranged in a V-shape,
A plurality of first cylinder bores formed in the first bank and arranged in the axial direction of the crankshaft;
A plurality of second cylinder bores formed in the second bank and arranged in the axial direction of the crankshaft;
A plurality of crank chambers in communication with one of the plurality of first cylinder bores and one of the plurality of second cylinder bores and arranged in the axial direction of the crankshaft;
A partition that rotatably supports the crankshaft and that separates the adjacent crank chambers in the axial direction of the crankshaft;
A through hole formed in each of the partition walls and connecting the adjacent crank chambers in the axial direction of the crankshaft;
A first female screw hole formed around the first cylinder bore in the first bank, and screwed with a first bolt for attaching a first cylinder head to the first bank;
And a second female screw hole formed around the second cylinder bore in the second bank and screwed with a second bolt for attaching a second cylinder head to the second bank.
The axis of the first female screw hole coincides with the stroke direction of the first piston reciprocating in the first cylinder bore, and the axis of the second female screw hole reciprocates in the second cylinder bore. A cylinder block of a V-type multi-cylinder internal combustion engine, which coincides with the stroke direction of
The through holes are formed in an inter-bank region provided between the first bank and the second bank which connect the first bank and the second bank in each of the partition walls, and Aside from the first cylinder bore with respect to the axis of the first female screw hole formed on the side of the inter-bank area around the first cylinder bore in the bank, and around the second cylinder bore in the second bank A cylinder block of a V-type multi-cylinder internal combustion engine, wherein the cylinder block is disposed on the opposite side to the second cylinder bore with respect to the axis of the second female screw hole formed on the inter-bank region side.   The inner circumferential surface of the through hole is formed of a first conical surface whose diameter increases as it approaches one of the adjacent crank chambers in the axial direction of the crankshaft, and of the crank chamber adjacent in the axial direction of the crankshaft. The cylinder block of the V-type multi-cylinder internal combustion engine according to claim 1, further comprising: a second conical surface expanding in diameter toward the other.   The inner circumferential surface of the through hole has a first straight portion extending along an axis of the first female screw hole and a second straight portion extending along an axis of the second female screw hole. The cylinder block of the V-type multi-cylinder internal combustion engine according to claim 1 or 2.