Cylinder block

Abstract

To inhibit reduction of a flow rate of a coolant when the coolant flows from a first upper passage and a second upper passage to a lower passage.SOLUTION: In a cylinder block 10, a plurality of cylinder bores, a water jacket 30 which surrounds the plurality of cylinder bores, and penetration passages 50 each of which extends between the adjacent cylinder bores and in which a coolant from the water jacket 30 flows are defined. Each penetration passage 50 has: a first upstream passage 60 whose upstream end is connected to the water jacket 30; a second upstream passage 70 whose upstream end is connected to the water jacket 30; and a lower passage 80 which is connected to a downstream end of the first upstream passage 60 and a downstream end of the second upstream passage 70. A passage cross sectional area of the lower passage 80 is larger than a passage cross sectional area of the first upstream passage 60 and larger than a passage cross sectional area of the second upstream passage 70.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a cylinder block. [Background technology]

[0002] Patent Document 1 describes a cylinder block. The cylinder block is partitioned into a plurality of cylinder bores, a water jacket, and a drill path, which is a through-passage. The plurality of cylinder bores are aligned in a row. The water jacket surrounds the plurality of cylinder bores. The through-passage extends in a cylindrical shape.

[0003] The through passage has a first upstream flow path, a second upstream flow path, a first downstream flow path, and a second downstream flow path. The first upstream flow path and the first downstream flow path are aligned in a straight line. The second upstream flow path and the second downstream flow path are aligned in a straight line.

[0004] The upstream end of the first upstream flow path is connected to the water jacket. The downstream end of the first upstream flow path is connected to the first downstream flow path and the second downstream flow path. The upstream end of the second upstream flow path is connected to the water jacket. The downstream end of the second upstream flow path is connected to the first downstream flow path and the second downstream flow path. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 10-288080 Summary of the Invention [Problem to be solved by the invention]

[0006] In the cylinder block described in Patent Document 1, one of the downstream flow paths may be omitted. That is, the through passage may have a first upstream flow path, a second upstream flow path, and a downstream flow path in which the lower end of the first upstream flow path and the lower end of the second upstream flow path are connected. When one of the downstream flow paths is omitted in the cylinder block described in Patent Document 1, the flow path cross-sectional area of ​​the downstream flow path is equal to the flow path cross-sectional area of ​​the first upstream flow path or the second upstream flow path. Therefore, there is a risk that the flow rate of the cooling water will decrease when the cooling water flows from the first upstream flow path and the second upstream flow path into the downstream flow path. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, the present invention provides a cylinder block having a block body that defines a plurality of cylinder bores, a water jacket surrounding the plurality of cylinder bores, and a through passage that extends between adjacent cylinder bores and through which cooling water from the water jacket flows, wherein the through passage has a first upstream flow path whose upstream end is connected to the water jacket, a second upstream flow path whose upstream end is connected to the water jacket, and a downstream flow path that is connected to the downstream end of the first upstream flow path and the downstream end of the second upstream flow path, wherein a downstream portion including the downstream end of the first upstream flow path extends in a columnar shape, a downstream portion including the downstream end of the second upstream flow path extends in a columnar shape, and an upstream portion including the upstream end of the downstream flow path extends in a columnar shape, and a flow path cross-sectional area of ​​the upstream portion of the downstream flow path is larger than a flow path cross-sectional area of ​​the downstream portion of the first upstream flow path and is also larger than a flow path cross-sectional area of ​​the downstream portion of the second upstream flow path.

[0008] According to the above configuration, the cross-sectional area of ​​the upstream portion of the downstream path is larger than the cross-sectional area of ​​the downstream portion of the first upstream path and is larger than the cross-sectional area of ​​the downstream portion of the second upstream path, thereby preventing a decrease in the flow rate of the cooling water when the cooling water flows from the first upstream path and the second upstream path into the downstream path. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a top view of a cylinder block according to one embodiment. [Figure 2] FIG. 2 is a cross-sectional view of the cylinder block of the embodiment taken along line 2-2 of FIG. [Figure 3] FIG. 3 is a cross-sectional view of a cylinder block according to a modified example. [Figure 4] FIG. 4 is a cross-sectional view of a cylinder block according to a modified example. [Figure 5] FIG. 5 is a cross-sectional view of a cylinder block according to a modified example. [Figure 6] FIG. 6 is a cross-sectional view of a cylinder block according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of a cylinder block will be described with reference to the drawings. <Outline of cylinder block> As shown in Fig. 1, the cylinder block 10 includes a block body 11. The block body 11 has a rectangular parallelepiped shape as a whole. The block body 11 has a deck surface 12. As shown in Fig. 2, a cylinder head 90 is mounted on the deck surface 12.

[0011] 1, the cylinder block 10 includes a plurality of cylinder bores 20, a water jacket 30, and an inlet hole 40. The plurality of cylinder bores 20, the water jacket 30, and the inlet hole 40 are defined in a block body 11.

[0012] The cylinder bores 20 are capable of accommodating pistons of an internal combustion engine so that they can reciprocate. The cylinder bores 20 are partitioned into cylindrical shapes. When the cylinder block 10 is viewed from above, the multiple cylinder bores 20 are aligned so that the centers C of the cylinder bores 20 are aligned on the same straight line. When the cylinder block 10 is viewed from above, the straight line connecting the centers C of the multiple cylinder bores 20 is defined as a boundary line BL. The boundary line BL passes through the thinnest part of the block body 11 located between the cylinder bores 20.

[0013] As shown in Figures 1 and 2, in the following description, the direction along the axis of the cylinder bore 20 is referred to as the up-down direction DZ. It is assumed that the cylinder bore 20 is located below the deck surface 12 in the up-down direction DZ, and the cylinder head 90 is mounted above the deck surface 12. Therefore, the viewpoint viewed from above facing the deck surface 12 is referred to as a top view. The direction along the boundary line BL is referred to as the depth direction DY. The direction perpendicular to both the up-down direction DZ and the depth direction DY is referred to as the width direction DX. The plane that includes the boundary line BL and is perpendicular to the width direction DX is referred to as a boundary plane BS.

[0014] As shown in Fig. 1, the water jacket 30 cools the block body 11 by the flow of cooling water. The water jacket 30 is partitioned in the block body 11. The water jacket 30 surrounds the multiple cylinder bores 20. In other words, the cylinder block 10 is of a so-called Siamese type, in which multiple cylinders are connected together.

[0015] The water jacket 30 is open to the deck surface 12. The entire upper area of ​​the water jacket 30 is open to the deck surface 12. In other words, the cylinder block 10 is of a so-called open deck type.

[0016] The inlet hole 40 supplies the cooling water pressure-fed from the water pump to the water jacket 30. The inlet hole 40 is located at approximately the same position as the center C of the cylinder bore 20 located at the end in the depth direction DY.

[0017] When the cylinder head 90 is mounted, part of the opening of the deck surface 12 on the side of the water jacket 30 where the inlet hole 40 is not located, across the boundary surface BS, is connected to the in-head water jacket of the cylinder head 90. Therefore, the cooling water in the water jacket 30 flows across the boundary surface BS as a whole from the side of the water jacket 30 where the inlet hole 40 is located to the side where it is not located, with the inlet hole 40 as the most upstream location.

[0018] Therefore, the portion of the water jacket 30 where the inlet hole 40 is located is located upstream of the portion of the water jacket 30 where the inlet hole 40 is not located, with the boundary surface BS as the boundary. In addition, the water jacket 30 is located upstream of the in-head water jacket of the cylinder head 90.

[0019] <Passageway> 2, the cylinder block 10 has a through passage 50. The through passage 50 is defined in the block body 11.

[0020] The through passage 50 extends between adjacent cylinder bores 20 in the block body 11. Cooling water from the water jacket 30 flows through the through passage 50, thereby cooling the block body 11, particularly the portion between the adjacent cylinder bores 20.

[0021] The through passage 50 has a first upstream passage 60, a second upstream passage 70, and a downstream passage 80. The upstream end of the through passage 50 is the upstream end of the first upstream passage 60. The downstream end of the through passage 50 is the downstream end of the downstream passage 80.

[0022] The first upstream flow path 60 is cylindrical. The upstream end of the first upstream flow path 60 is connected to a portion of the water jacket 30 on the side where the inlet hole 40 is located, with the boundary line BL as the boundary. The upstream end of the first upstream flow path 60 is connected to the vicinity of the bottom of the water jacket 30 in the up-down direction DZ. The downstream end of the first upstream flow path 60 is connected to the upstream end of the downstream flow path 80. The downstream end of the first upstream flow path 60 is located on the side where the inlet hole 40 is not located relative to the boundary surface BS in the width direction DX. That is, in this embodiment, all portions of the first upstream flow path 60, including the downstream end thereof, extend in a cylindrical shape.

[0023] The second upstream flow path 70 is cylindrical. The upstream end of the second upstream flow path 70 is connected to a portion of the water jacket 30 on the side where the inlet hole 40 is located, with the boundary surface BS as the boundary. The upstream end of the second upstream flow path 70 is connected to the vicinity of the position of the opening of the water jacket 30 in the vertical direction DZ. Therefore, the upstream end of the second upstream flow path 70 is located above the upstream end of the first upstream flow path 60. The downstream end of the second upstream flow path 70 is connected to the vicinity of the upstream end of the downstream flow path 80. The downstream end of the second upstream flow path 70 is located on the side of the boundary surface BS where the inlet hole 40 is not located in the width direction DX. That is, in this embodiment, the entire portion of the second upstream flow path 70, including its downstream end, extends cylindrically.

[0024] The downstream flow path 80 is cylindrical. That is, the entire downstream flow path 80, including its upstream end, extends in a cylindrical shape. The axis of the downstream flow path 80 extends parallel to the axis of the first upstream flow path 60. The axis of the downstream flow path 80 is aligned with the axis of the first upstream flow path 60. Therefore, when viewed along the axis of the first upstream flow path 60, the axis of the first upstream flow path 60 coincides with the axis of the downstream flow path 80. When viewed along the axis of the first upstream flow path 60, the first upstream flow path 60 overlaps with the downstream end of the downstream flow path 80.

[0025] The downstream end of the downstream flow path 80 opens to the deck surface 12. Although not shown, when the cylinder head 90 is mounted, the downstream end of the downstream flow path 80 is connected to an in-head water jacket of the cylinder head 90. Therefore, the downstream end of the first upstream flow path 60 and the downstream end of the second upstream flow path 70 are located on the same side as the downstream end of the downstream flow path 80 with respect to the boundary surface BS in the width direction DX.

[0026] The upstream end of the downstream flow path 80 is connected to the downstream end of the first upstream flow path 60. A side surface near the upstream end of the downstream flow path 80 is connected to the downstream end of the second upstream flow path 70. The upstream end of the downstream flow path 80 is located on the same side as the downstream end of the downstream flow path 80 in the width direction DX with respect to the boundary surface BS. In other words, the downstream flow path 80 extends only from its downstream end to just before the boundary surface BS in the width direction DX, and does not extend all the way to the boundary surface BS.

[0027] The diameter of the circle of the flow path cross section of the first upstream flow path 60 is equal to the diameter of the circle of the flow path cross section of the second upstream flow path 70. Therefore, the flow path cross-sectional area of ​​the first upstream flow path 60 is equal to the flow path cross-sectional area of ​​the second upstream flow path 70. Note that the flow path cross-sectional area is the area of ​​a cross section perpendicular to the axis along which the flow path extends.

[0028] The diameter of the circle of the flow path cross section of the downstream flow path 80 is larger than the diameter of the circle of the flow path cross section of the first upstream flow path 60. The diameter of the circle of the flow path cross section of the downstream flow path 80 is approximately twice the diameter of the circle of the flow path cross section of the first upstream flow path 60. Therefore, the flow path cross section area of ​​the downstream flow path 80 is larger than the flow path cross section area of ​​the first upstream flow path 60. Furthermore, when viewed along the axis along which the first upstream flow path 60 extends, the entire area of ​​the first upstream flow path 60 is located within the range of the outer edge of the downstream flow path 80.

[0029] The diameter of the circular flow path cross section of the downstream flow path 80 is larger than the diameter of the circular flow path cross section of the second upstream flow path 70. The diameter of the circular flow path cross section of the downstream flow path 80 is approximately twice the diameter of the circular flow path cross section of the second upstream flow path 70. Therefore, the flow path cross-sectional area of ​​the downstream flow path 80 is larger than the flow path cross-sectional area of ​​the second upstream flow path 70.

[0030] The cross-sectional area of ​​the downstream flow path 80 is larger than the sum of the cross-sectional areas of the first upstream flow path 60 and the second upstream flow path 70. Specifically, the cross-sectional area of ​​the downstream flow path 80 is about four times the sum of the cross-sectional areas of the first upstream flow path 60 and the second upstream flow path 70. In other words, the cross-sectional area of ​​the upstream portion of the downstream flow path 80 is larger than the sum of the cross-sectional areas of the downstream portion of the first upstream flow path 60 and the second upstream flow path 70.

[0031] <Operation of one embodiment> In the cylinder block 10, cooling water pumped from the water pump is supplied to the water jacket 30 through the inlet hole 40. The cooling water supplied to the water jacket 30 flows from the upstream side to the downstream side in the water jacket 30 and also flows through the through passage 50. In the through passage 50, the cooling water flows from the upstream end to the downstream end of the first upstream passage 60. The cooling water also flows from the upstream end to the downstream end of the second upstream passage 70. Then, near the upstream end of the downstream passage 80, the cooling water flowing from the first upstream passage 60 and the cooling water flowing from the second upstream passage 70 join together.

[0032] <Effects of one embodiment> (1) In the above embodiment, the flow path cross-sectional area of ​​the upstream portion of the downstream flow path 80 is larger than the flow path cross-sectional area of ​​the downstream portion of the first upstream flow path 60, and is also larger than the flow path cross-sectional area of ​​the downstream portion of the second upstream flow path 70. Therefore, when the cooling water flows from the first upstream flow path 60 and the second upstream flow path 70 into the downstream flow path 80, a decrease in the flow rate of the cooling water can be suppressed.

[0033] (2) In the above embodiment, the flow path cross-sectional area of ​​the downstream flow path 80 is larger than the sum of the flow path cross-sectional area of ​​the first upstream flow path 60 and the flow path cross-sectional area of ​​the second upstream flow path 70. Therefore, when the cooling water flows from the first upstream flow path 60 and the second upstream flow path 70 into the downstream flow path 80, a shortage in the flow rate of the cooling water that can flow can be suppressed.

[0034] (3) In the above embodiment, in the width direction DX, the downstream end of the first upstream flow path 60 and the downstream end of the second upstream flow path 70 are located on the same side of the boundary plane BS as the downstream end of the downstream flow path 80. The upstream end of the downstream flow path 80 is located on the same side of the boundary plane BS as the downstream end of the downstream flow path 80 in the width direction DX.

[0035] Because the distance between adjacent cylinder bores 20 is short on the boundary surface BS, increasing the flow passage cross section of the through passage 50 requires increasing the overall size of the cylinder block 10. According to the above embodiment, by positioning the downstream end of the downstream flow passage 80 only on the same side of the boundary surface BS as the downstream end of the downstream flow passage 80 in the width direction DX, it is possible to prevent the overall size of the cylinder block 10 from increasing in the depth direction DY.

[0036] (4) The downstream end of the downstream flow path 80 opens to the deck surface 12. The first upstream flow path 60 is cylindrical. The downstream flow path 80 is cylindrical. When viewed along the central axis of the first upstream flow path 60, the first upstream flow path 60 overlaps the downstream end of the downstream flow path 80. According to the above embodiment, the manufacturer of the cylinder block 10 first processes a hole having a diameter equal to the circular cross-section of the first upstream flow path 60, starting from the location where the downstream end of the downstream flow path 80 will be located. Then, the manufacturer processes a hole having a diameter equal to the circular cross-section of the downstream flow path 80, starting from the location where the downstream end of the downstream flow path 80 will be located, thereby forming the downstream flow path 80 and the first upstream flow path 60. Therefore, the cylinder block 10 does not require excessively complicated work to manufacture.

[0037] (5) When viewed along the axis of the first upstream flow path 60, the entire area of ​​the first upstream flow path 60 is located within the range of the outer edge of the downstream flow path 80. According to the above embodiment, the manufacturer of the cylinder block 10 first processes a hole having a diameter equal to the diameter of the cross-sectional circle of the first upstream flow path 60, starting from the location where the downstream end of the downstream flow path 80 will be located. Then, the manufacturer can form the downstream flow path 80 by using the hole as a guide to process a hole having a diameter larger than the diameter of the cross-sectional circle of the first upstream flow path 60. Therefore, the cylinder block 10 is easy to process when forming the downstream flow path 80.

[0038] <Other embodiments> The above embodiment can be modified as follows. This embodiment and the following modifications can be combined with each other to the extent that no technical contradiction occurs. In the following drawings showing the modifications, the same components as those in the above embodiment are designated by the same numbers, and their description will be omitted.

[0039] In the above embodiment, the cylinder block 10 may have three or more upstream passages. 3, the cylinder block 110 of the modified example has a through passage 150. The through passage 150 has multiple upstream passages: a first upstream passage 160, a second upstream passage 170, and a third upstream passage 171. The upstream end of the third upstream passage 171 is located above the upstream end of the second upstream passage 170 in the vertical direction DZ.

[0040] The through passage 150 has a first downstream passage 181 and a second downstream passage 182 as the downstream passage 180. The first downstream passage 181 and the second downstream passage 182 are aligned on the axis of the first upstream passage 160.

[0041] The first downstream flow path 181 is cylindrical. The first downstream flow path 181 includes the upstream end of the downstream flow path 180. The second downstream flow path 182 is cylindrical. The diameter of the circular flow path cross section of the second downstream flow path 182 is larger than the diameter of the circular flow path cross section of the first downstream flow path 181.

[0042] The downstream end of the first upstream path 160 and the downstream end of the second upstream path 170 are connected to a first downstream path 181. The cross-sectional area of ​​the first downstream path 181 is larger than the sum of the cross-sectional areas of the first upstream path 160 and the second upstream path 170.

[0043] The downstream end of the third upstream path 171 is connected to the second downstream path 182. The path cross-sectional area of ​​the second downstream path 182 is larger than the sum of the path cross-sectional areas of the first upstream path 160 and the third upstream path 171. In the above modification, the first downstream path 181 including the upstream end of the downstream path 180 extends in a cylindrical shape, and the path cross-sectional area of ​​the first downstream path 181 is larger than the path cross-sectional area of ​​the first upstream path 160 and is also larger than the path cross-sectional area of ​​the second upstream path 170.

[0044] In this way, in the through passage 150 in which the flow paths merge multiple times, the cross-sectional area of ​​the flow path after merging may be larger than any of the cross-sectional areas of the flow paths before merging at each merging point. In this case, the cylinder block 110 can prevent the flow of cooling water from being obstructed due to an insufficient flow rate at each merging point.

[0045] In the above embodiment, the first upstream flow path 60 does not have to be linear. As shown in FIG. 4 , the cylinder block 210 of the modified example has a through passage 250. The through passage 250 has a first upstream passage 260, a second upstream passage 270, and a downstream passage 280. The first upstream passage 260 includes a cylindrical first portion 261 and a cylindrical second portion 262. The axis of the second portion 262 is aligned with the axis of the downstream passage 280. The downstream end of the second portion 262 is connected to the upstream end of the downstream passage 280. Meanwhile, the axis of the first portion 261 intersects with the axis of the second portion 262. The downstream end of the first portion 261 is connected to the upstream end of the second portion 262. In this modified example, the upstream end of the first portion 261 is located above the center of the water jacket 30 in the vertical direction DZ. The downstream end of the first portion 261 is located lower than the upstream end of the first portion 261 in the up-down direction DZ. In the above modification, the second portion 262, which is the downstream portion including the downstream end of the first upstream path 260, extends in a cylindrical shape. In this case, the flow path cross-sectional area of ​​the downstream path 280 only needs to be larger than the flow path cross-sectional area of ​​the second portion 262.

[0046] In this way, the first upstream flow path 260 does not have to extend in a single straight line, but may be composed of multiple straight line sections. During manufacturing of the cylinder block 210, the first section 261 is machined from the side where the inlet hole 40 of the water jacket 30 is located, and the second section 262 is machined from the side where the inlet hole 40 of the water jacket 30 is not located, thereby avoiding the need to machine excessively deep holes.

[0047] In the above embodiment, the downstream end of the through passage 50 does not have to open to the deck surface 12. 5, the cylinder block 310 of the modified example has a through passage 350. The through passage 350 has a first upstream passage 360, a second upstream passage 370, and a downstream passage 380. The downstream end of the downstream passage 380 is the downstream end of the through passage 350. The downstream end of the downstream passage 380 is located on the opposite side of the boundary plane BS from the upstream end of the first upstream passage 360 ​​in the width direction DX. The downstream end of the downstream passage 380 is connected to the water jacket 30.

[0048] In this way, the downstream end of the through passage 350 does not have to open to the deck surface 12, and may be connected to the water jacket 30. If it is connected to the water jacket 30, the cooling water can flow through the through passage 350 even if the in-head water jacket of the cylinder head 90 is not connected to the through passage 350.

[0049] In the above embodiment, when viewed along the axis of the first upstream flow path 60, the first upstream flow path 60 does not have to overlap with the downstream end of the downstream flow path 80. As shown in FIG. 6 , the cylinder block 410 of the modified example has a through passage 450. The through passage 450 has a first upstream passage 460, a second upstream passage 470, and a downstream passage 480. The axis of the downstream passage 480 is substantially parallel to the vertical direction DZ. The axis of the first upstream passage 460 intersects with the axis of the downstream passage 480. The upstream end of the first upstream passage 460 is located above the center of the water jacket 30 in the vertical direction DZ. The downstream end of the first upstream passage 460 is located below the upstream end of the first upstream passage 460 in the vertical direction DZ. Therefore, when viewed along the axis of the first upstream passage 460, the first upstream passage 460 does not overlap the downstream end of the downstream passage 480.

[0050] In this case, the first upstream flow path 460 may be processed from the side of the water jacket 30 where the inlet hole 40 is located, and the downstream flow path 480 may be processed from the side of the water jacket 30 where the inlet hole 40 is not located.

[0051] In the above embodiment, when viewed along the axis along which the first upstream flow path 60 extends, the entire area of ​​the first upstream flow path 60 does not have to be located within the range of the outer edge of the downstream flow path 80. In other words, a part of the first upstream flow path 60 may be located outside the range of the outer edge of the downstream flow path 80. In other words, when viewed along the axis along which the first upstream flow path 60 extends, even if the entire area of ​​the first upstream flow path 60 is not located within the range of the outer edge of the downstream flow path 80, a part of the first upstream flow path 60 may overlap the downstream end of the downstream flow path 80.

[0052] In the above embodiment, in the width direction DX, the downstream end of the downstream flow path 80 may be located on the opposite side of the boundary plane BS from the downstream end of the downstream flow path 80. In this case, the downstream ends of the first upstream flow path 60 and the second upstream flow path 70 may be located on the same side of the boundary plane BS as the upstream end of the first upstream flow path 60. If there is a sufficient thickness between adjacent cylinder bores 20 in the block main body 11, the downstream flow path 80 can be extended in this manner.

[0053] In the above embodiment, the cross-sectional area of ​​the downstream flow path 80 may be equal to or smaller than the sum of the cross-sectional area of ​​the first upstream flow path 60 and the cross-sectional area of ​​the second upstream flow path 70. If the cross-sectional area of ​​the downstream flow path 80 is larger than the cross-sectional area of ​​the first upstream flow path 60 and larger than the cross-sectional area of ​​the second upstream flow path 70, a decrease in the flow rate can be suppressed.

[0054] In the above embodiment, each flow path does not have to be cylindrical in shape. In this case, it is sufficient that the downstream portion including the downstream end of the first upstream flow path 60, the downstream portion including the downstream end of the second upstream flow path 70, and the upstream portion including the upstream end of the downstream flow path 80 are cylindrical. For example, these portions may be rectangular or cylindrical with an elliptical cross section. It is sufficient that the cross-sectional area of ​​the upstream portion of the downstream flow path 80 is larger than the cross-sectional area of ​​the downstream portion of the first upstream flow path 60 and larger than the cross-sectional area of ​​the downstream portion of the second upstream flow path 70.

[0055] The position of the inlet hole 40 is not limited to the example in the above embodiment. For example, it may be located between adjacent cylinder bores 20 in the depth direction DY. The position of the inlet hole 40 may be changed as appropriate as long as the relationship between the upstream and downstream sides of the cooling water does not change between one side and the other side of the boundary surface BS in the width direction DX. [Explanation of symbols]

[0056] 10, 110, 210, 310, 410... Cylinder block 11...Block body 12...Deck surface 20...Cylinder bore 30...Water jacket 40...Inflow hole 50, 150, 250, 350, 450...through passage 60, 160, 260, 360, 460...1st upstream path 70, 170, 270, 370, 470…Second upstream route 80, 180, 280, 380, 480...downstream path 90...Cylinder head BL…Borderline BS…Boundary surface C…center

Claims

1. A plurality of cylinder bores; a water jacket surrounding the plurality of cylinder bores; a through passage extending between adjacent cylinder bores and through which cooling water from the water jacket flows, the through passage has a first upstream flow path having an upstream end connected to the water jacket, a second upstream flow path having an upstream end connected to the water jacket, and a downstream flow path connected to a downstream end of the first upstream flow path and a downstream end of the second upstream flow path, a downstream portion including a downstream end of the first upstream flow path extends in a columnar shape, a downstream portion including a downstream end of the second upstream flow path extends in a columnar shape, an upstream portion including an upstream end of the downstream flow path extends in a columnar shape, The cross-sectional area of ​​the downstream portion of the downstream flow path is larger than the cross-sectional area of ​​the downstream portion of the first upstream flow path and is also larger than the cross-sectional area of ​​the downstream portion of the second upstream flow path. Cylinder block.

2. The cross-sectional area of ​​the upstream portion of the downstream flow path is larger than the sum of the cross-sectional area of ​​the downstream portion of the first upstream flow path and the cross-sectional area of ​​the downstream portion of the second upstream flow path.

2. The cylinder block according to claim 1.

3. In a width direction perpendicular to both a boundary line that is a straight line connecting the centers of adjacent cylinder bores when viewed from a direction along the axis of extension of the cylinder bores and the axis of extension of the cylinder bores, When a plane including the boundary line and perpendicular to the width direction is defined as a boundary surface, a downstream end of the first upstream flow path and a downstream end of the second upstream flow path are located on the same side of the boundary surface as a downstream end of the downstream flow path, The upstream end of the downstream flow path is located on the same side of the boundary surface as the downstream end of the downstream flow path.

2. The cylinder block according to claim 1.

4. The downstream end of the downstream passage is open to the deck surface, The first upstream flow path is cylindrical, The downstream flow path is cylindrical, When viewed along an axis along which the first upstream flow path extends, the first upstream flow path overlaps with a downstream end of the downstream flow path.

2. The cylinder block according to claim 1.

5. When viewed along an axis along which the first upstream flow path extends, the entire area of ​​the first upstream flow path is located within the range of an outer edge of the downstream flow path.

5. The cylinder block according to claim 4.

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