JP2021067208A - Cylinder block - Google Patents

Abstract

To provide a cylinder block including an oil return passage which is easy to discharge oil while facilitating cooling of the oil.SOLUTION: A cylinder block 10 constituting an internal combustion engine has an upper part to which a cylinder head is attached, and a lower part to which an oil pan is attached. The cylinder block 10 includes a plurality of cylinder bores 12, a water jacket 13 arranged to surround the cylinder bores 12, and an oil return passage 20 for returning oil in the cylinder head to the oil pan. The oil return passage 20 is formed at a position where the water jacket 13 is interposed between the oil return passage 20 and the cylinder bores 12. The oil return passage 20 has a first net structure portion 31 as a net structure portion that is divided into a net shape by a plurality of crosslinks having different directions. The first net structure portion 31 is provided in a region on the oil return passage 20 through which the oil passes in a high temperature state.SELECTED DRAWING: Figure 3

Description

The present invention relates to a cylinder block of an internal combustion engine.

Patent Document 1 discloses a cylinder block provided with an oil return passage for returning the oil supplied from the oil pan by the oil pump to the oil pan. The oil return passage is juxtaposed with the water jacket. An oil regulating member is inserted in the oil return passage. The oil regulation member narrows the flow path of the oil return passage so that even if the amount of oil is small, the oil flows on the water jacket side in the oil return passage.

Japanese Unexamined Patent Publication No. 2013-174159

When the oil is in contact with the wall surface, the oil flow is slow due to the viscosity of the oil, and when the oil is not in contact with the wall surface, the oil flow is faster than when the oil is in contact with the wall surface. .. Therefore, even if the flow path of the oil return passage is narrowed to allow oil to flow on the water jacket side as in the cylinder block disclosed in Patent Document 1, the oil flows at a position away from the wall surface on the water jacket side. The oil is discharged into the oil pan without much heat exchange. That is, heat exchange is actively performed only in a part of the oil that is in contact with the wall surface on the water jacket side. The narrower the flow path of the oil return passage so that more oil flows closer to the wall surface on the water jacket side of the oil return passage, the greater the resistance when the oil passes and the more the oil passes to the oil pan. Oil discharge may be delayed. That is, as the oil return passage provided in the cylinder block, an oil return passage in which oil is easily discharged while promoting cooling of the oil is required.

The cylinder block for solving the above problems is a cylinder block in which a cylinder head is attached to the upper part and an oil pan is attached to the lower part to form an internal combustion engine, and surrounds a plurality of cylinder bores and the plurality of cylinder bores. The water jacket is provided with an oil return passage for returning the oil in the cylinder head to the oil pan, and the oil return passage is a position where the water jacket is sandwiched between the oil return passage and the cylinder bore. It has a network structure that is formed in a network and is divided into a network by a plurality of bridges in different directions, and the network structure is located in a region of the oil return passage through which oil passes at a high temperature. The gist is that it is provided.

According to the above configuration, since the mesh structure portion is provided in the oil return passage, the oil passing through the oil return passage collides with the crosslink. Therefore, the flow of oil passing through the oil return passage is disturbed. Since the oil is diffused in the oil return passage, the oil staying time in the oil return passage is longer than that in the case where the mesh structure is not provided. This promotes heat exchange between the cooling water flowing through the water jacket and the oil, and the temperature of the oil tends to decrease.

If a mesh structure is provided in the oil return passage, the resistance when the oil passes increases. However, in the above configuration, since the mesh structure is provided in the region where the oil passes in a high temperature state, the resistance is excessively increased. Can be suppressed.

Further, since the magnitude of the resistance can be adjusted by the arrangement position of the mesh structure or the roughness of the mesh, the arrangement of the mesh structure is assumed assuming that the amount of oil passing through the oil return passage is large. By setting the installation position or the roughness of the mesh, it is possible to prevent the oil discharge from being delayed.

If the amount of oil passing through the oil return passage is small, the oil that collides with the cross-linking may diffuse and adhere to the wall surface, or the oil may adhere to the cross-linking. Therefore, as compared with the case where the mesh structure portion is not provided, the staying time of the oil in the oil return passage becomes longer, and the contact area between the oil and the cylinder block increases. As a result, even when the amount of oil passing through the oil return passage is small, heat exchange between the cooling water and the oil is promoted, and the temperature of the oil tends to decrease.

That is, according to the above configuration, the oil is easily discharged while promoting the cooling of the oil.

The schematic diagram which shows the internal combustion engine including the cylinder block of 1st Embodiment. The plan view which shows the cylinder block of 1st Embodiment. FIG. 2 is a cross-sectional view taken along the line 3-3 in FIG. FIG. 2 is a cross-sectional view taken along the line 4-4 in FIG. The cross-sectional view which shows the cylinder block of 2nd Embodiment.

(First Embodiment)
Hereinafter, the cylinder block 10 of the first embodiment will be described with reference to FIGS. 1 to 4.

FIG. 1 shows an internal combustion engine 90 including a cylinder block 10. The internal combustion engine 90 is an in-line 4-cylinder internal combustion engine in which four cylinder bores are arranged in a straight line. An oil pan 91 is attached to the lower part of the cylinder block 10. A cylinder head 92 is attached to the upper part of the cylinder block 10. A cylinder head cover 94 is attached to the upper part of the cylinder head 92.

The internal combustion engine 90 includes an oil pump that pumps the oil stored in the oil pan 91 and supplies it to each part of the internal combustion engine 90. The internal combustion engine 90 includes a discharge passage for dropping the supplied oil into the oil pan 91. The discharge passage is composed of an in-head passage included in the cylinder head 92 and an oil return passage 20 included in the cylinder block 10. The cylinder head 92 is provided with a plurality of passages in the head. The plurality of in-head passages are connected to the oil return passage 20 on the surface where the cylinder head 92 and the cylinder block 10 are connected. FIG. 1 shows the first head passage 93A among the head passages.

FIG. 2 shows the cylinder block 10 as viewed from the cylinder head 92 side. The cylinder block 10 includes four cylinder bores 12. The cylinder bores 12 are arranged in a straight line. FIG. 2 shows an arrow indicating the cylinder arrangement direction L1 which is the direction in which the cylinder bores 12 are arranged.

The cylinder block 10 includes a water jacket 13 that circulates cooling water. The water jacket 13 is arranged so as to surround the four cylinder bores 12.

The cylinder bore 12 and the water jacket 13 are open to the deck surface 11 on which the cylinder head 92 is attached.
The oil return passage 20 provided in the cylinder block 10 is provided on one side of the deck surface 11 in a direction orthogonal to the cylinder arrangement direction L1 with respect to the four cylinder bores 12. The oil return passage 20 is arranged outside the water jacket 13. That is, the oil return passage 20 is formed at a position where the water jacket 13 is sandwiched between the oil return passage 20 and the cylinder bore 12. The oil return passage 20 is open to the deck surface 11 like the cylinder bore 12 and the water jacket 13.

The portion of the oil return passage 20 on the deck surface 11 side extends in the cylinder arrangement direction L1 as shown in FIG. One end of the four cylinder bores 12 in the cylinder arrangement direction L1 so that the portion of the oil return passage 20 on the deck surface 11 side is juxtaposed with the water jacket 13 in the direction orthogonal to the cylinder arrangement direction L1 on the deck surface 11. Extends from the cylinder bore 12 of the above toward the cylinder bore 12 at the other end.

Further, a bolt hole 14 is opened on the deck surface 11. A bolt connecting the cylinder block 10 and the cylinder head 92 is inserted into the bolt hole 14. Bolt holes 14 are arranged around the water jacket 13. The bolt hole 14 on the oil return passage 20 side is arranged between the water jacket 13 and the oil return passage 20.

As shown in FIGS. 3 and 4, the oil return passage 20 is composed of a first passage 21 on the cylinder head 92 side and a second passage 22 on the oil pan 91 side.
As shown in FIG. 4, the first passage 21 extends in the cylinder arrangement direction L1. The length of the second passage 22 in the cylinder arrangement direction L1 is shorter than that of the first passage 21. That is, the passage cross-sectional area of the second passage 22 is smaller than that of the first passage 21. The second passage 22 is arranged at the center of the cylinder block 10 in the cylinder arrangement direction L1.

As shown in FIG. 3, the depth of the first passage 21 of the oil return passage 20 from the deck surface 11 is shorter than the depth of the water jacket 13. A spacer 41 is inserted in the water jacket 13. The spacer 41 reduces the cross-sectional area of the flow path of the water jacket 13 to limit the range in which the cooling water flows. In the cross-sectional structure at the position shown in FIG. 3, the cooling water flows to a depth similar to the depth of the first passage 21 on the oil return passage 20 side of the water jacket 13.

In FIG. 3, arrows indicating an upper vertical direction and a lower vertical direction are displayed. Further, FIG. 3 shows the cylinder block 10 in a posture in which the internal combustion engine 90 is mounted on the vehicle, and the central axis of the cylinder bore 12 is displayed as the axis C. As shown in FIG. 3, the axis C is inclined with respect to the vertical direction. That is, the internal combustion engine 90 is mounted on the vehicle in an inclined posture with respect to the vertical direction.

As shown in FIG. 4, the first head passage 93A, the second head passage 93B, the third head passage 93C, and the fourth head passage 93D included in the cylinder head 92 communicate with the first passage 21. .. The passages 93A in the first head to the passages 93D in the fourth head are arranged in the cylinder arrangement direction L1 at intervals. The oil that has flowed into the oil return passage 20 from each of the first head passage 93A to the fourth head passage 93D passes through the first passage 21 and flows into the second passage 22. The oil that has spread in the cylinder arrangement direction L1 collects and flows into the second passage 22.

As shown in FIGS. 3 and 4, the first passage 21 is provided with a first mesh structure portion 31. In the first mesh structure portion 31, the inside of the first passage 21 is divided into a mesh shape by a plurality of bridges having different directions. Although the first network structure portion 31 is schematically shown in FIGS. 3 and 4, the plurality of crosslinks are three-dimensionally overlapped. The first mesh structure portion 31 can be formed, for example, by filling the first passage 21 with steel wool, which is a metal processed into a fibrous form.

As shown in FIG. 4, the second passage 22 is provided with a second mesh structure portion 32. In the second mesh structure portion 32, similarly to the first mesh structure portion 31, the inside of the second passage 22 is divided into a mesh shape by a plurality of crosslinks having different directions. However, the second mesh structure portion 32 has a coarser mesh than the first mesh structure portion 31. That is, the density of the crosslinks in the second network structure portion 32 is lower than that in the first network structure portion 31. The second mesh structure portion 32 can be formed, for example, by accommodating a wire mesh in which rod-shaped metals are welded in a grid pattern in the second passage 22. At the end of the second passage 22 on the first passage 21 side, a second mesh structure portion 32 is provided up to the boundary between the second passage 22 and the first passage 21. The second mesh structure portion 32 is not provided at the end of the second passage 22 on the oil pan 91 side.

The temperature of the oil flowing through the oil return passage 20 decreases due to heat exchange as the oil flows down. Therefore, in the oil return passage 20, the temperature of the oil tends to be higher on the cylinder head 92 side than on the oil pan 91 side. That is, the first passage 21 is a region through which oil passes in a state where the temperature is higher than that of the second passage 22. The first mesh structure portion 31 is provided in the first passage 21 of the oil return passage 20, which is a region through which oil passes in a high temperature state. The second mesh structure portion 32 is provided on the side of the first passage 21 which is a region of the second passage 22 through which oil passes in a high temperature state. That is, in the cylinder block 10, the first and second mesh structure portions 31 and 32 are provided as the mesh structure portions in the region of the oil return passage 20 through which the oil passes in a high temperature state.

The operation of this embodiment will be described.
In the cylinder block 10, since the oil return passage 20 is provided with the first mesh structure portion 31 and the second mesh structure portion 32, the oil passing through the oil return passage 20 collides with the crosslink. Therefore, the flow of oil passing through the oil return passage 20 is disturbed. The oil is diffused in the oil return passage 20, and the oil staying time in the oil return passage 20 becomes longer as compared with the case where the first mesh structure portion 31 and the second mesh structure portion 32 are not provided.

When the amount of oil passing through the oil return passage 20 is small, the oil colliding with the crosslinks in the first mesh structure portion 31 and the second mesh structure portion 32 diffuses and adheres to the wall surface of the oil return passage 20. Or oil adheres to the crosslinks. Therefore, as compared with the case where the first mesh structure portion 31 and the second mesh structure portion 32 are not provided, the staying time of the oil in the oil return passage 20 is longer, and the oil and the cylinder block 10 are combined. The contact area increases.

Further, in the oil return passage 20, the first passage 21 having a wide passage is provided with a fine-meshed first mesh structure portion 31, and the second passage 22 having a narrow passage is provided with a coarse-meshed second mesh structure portion 32. Is provided. The oil that has passed through the first passage 21 collects and flows into the second passage 22, but since the mesh of the second mesh structure portion 32 is coarse, the resistance when the oil passes through the second passage 22 is unlikely to increase. ..

The effect of this embodiment will be described.
(1-1) The first mesh structure portion 31 and the second mesh structure portion 32 can prolong the staying time of oil in the oil return passage 20. As a result, heat exchange between the cooling water flowing through the water jacket 13 and the oil passing through the oil return passage 20 is promoted, and the temperature of the oil tends to decrease.

(1-2) Oil adheres to the crosslinks of the first network structure portion 31 and the second network structure portion 32, or the oil that collides with the crosslinks diffuses and adheres to the wall surface of the oil return passage 20. As a result, even when the amount of oil passing through the oil return passage 20 is small, heat exchange between the cooling water and the oil is promoted, and the temperature of the oil tends to decrease.

(1-3) When the internal combustion engine 90 is mounted on the vehicle in an inclined posture as shown in FIG. 3, if the amount of oil passing through the oil return passage 20 is small, the water jacket 13 side in the oil return passage 20 Oil does not easily adhere to the wall surface. In this regard, in the cylinder block 10, oil can be diffused by the first mesh structure portion 31 and the second mesh structure portion 32, so that the oil can also be adhered to the wall surface on the water jacket 13 side in the oil return passage 20. it can. This promotes heat exchange between the cooling water and the oil, and the temperature of the oil tends to decrease.

(1-4) In the second passage 22, a second mesh structure portion 32 that forms a coarse mesh is adopted. Therefore, the resistance when the oil passes through the second passage 22 is unlikely to increase. It is possible to suppress a decrease in the flow velocity of the oil in the second passage 22 where the oil collects and the flow rate increases. It is possible to prevent the oil from being discharged to the oil pan 91 through the oil return passage 20 from being delayed. Further, since the mesh structure portion of the second passage 22 having a smaller flow path cross-sectional area than the first passage 21 has a coarse mesh, the flow velocity of the oil passing through the first passage 21 and the second passage 22 are adjusted. The difference from the flow velocity of the passing oil can be reduced.

(1-5) When the inside of the oil return passage 20 is divided into a mesh, the resistance when the oil passes increases. In this regard, in the cylinder block 10, the first mesh structure portion 31 is provided in the region of the oil return passage 20 through which the oil passes in a high temperature state. A second mesh structure portion 32 is provided on the side of the first passage 21 which is a region of the second passage 22 through which oil passes when the temperature is high. As described above, the first mesh structure portion 31 and the second mesh structure portion 32 are provided in the region of the oil return passage 20 through which the oil passes in a high temperature state. As a result, it is possible to prevent the resistance when the oil passes from being excessively increased while providing the first mesh structure portion 31 and the second mesh structure portion 32 in the oil return passage 20. That is, it becomes easier to discharge the oil while promoting the cooling of the oil.

(Second Embodiment)
The cylinder block 110 of the second embodiment will be described with reference to FIG. The structure of the oil return passage 120 of the cylinder block 110 of the second embodiment is different from that of the first embodiment. Other configurations are the same as those in the first embodiment.

As shown in FIG. 5, the cylinder block 110 includes an oil return passage 120. Similar to the first passage 21 of the oil return passage 20 in the first embodiment, the oil return passage 120 has a cylinder head 92 side extending in the cylinder arrangement direction L1. The oil return passage 120 has a shorter length in the cylinder arrangement direction L1 toward the oil pan 91 side. That is, the lower side in FIG. 5 has a smaller flow path cross-sectional area of the oil return passage 120.

The oil return passage 120 is provided with a first guide plate 123 that guides the oil that has flowed into the oil return passage 120 from the second head inner passage 93B. The oil return passage 120 is provided with a second guide plate 124 that guides the oil that has flowed into the oil return passage 120 from the third head inner passage 93C. The first guide plate 123 and the second guide plate 124 are bimetals in which two types of metal plates having different coefficients of thermal expansion are bonded together.

The first guide plate 123 and the second guide plate 124 are linear as shown by a solid line in FIG. 5 when the temperature of the adhering oil is low. The first guide plate 123 and the second guide plate 124 are curved as shown by the alternate long and short dash line in FIG. 5 when the temperature of the adhering oil is high. The first guide plate 123 and the second guide plate 124 are attached so as to face the center of the cylinder block 110 in the cylinder arrangement direction L1 when the oil temperature is high.

The oil return passage 120 is provided with a mesh structure portion 133. Similar to the first mesh structure portion 31 in the first embodiment, the mesh structure portion 133 divides the inside of the oil return passage 120 into a mesh shape by a plurality of crosslinks having different directions. As shown in FIG. 5, the mesh structure portion 133 is provided in a part of the oil return passage 120. The oil return passage 120 does not have a structure that divides the inside of the oil return passage 120 into a mesh shape except for the mesh structure portion 133. The mesh structure portion 133 is located between the first guide plate 123 and the second guide plate 124 in the cylinder arrangement direction L1. More specifically, the mesh structure portion 133 flows in from the second head inner passage 93B and the third head inner passage 93C when the first guide plate 123 and the second guide plate 124 are curved as shown by the alternate long and short dash line. It is placed in a position where the oil can pass through.

That is, the mesh structure portion 133 is provided in the region of the oil return passage 120 through which the oil passes in a high temperature state.
The operation of this embodiment will be described.

In the cylinder block 110, when the temperature of the oil is high, the oil is guided so as to pass through the mesh structure portion 133 by bending the first guide plate 123 and the second guide plate 124. On the other hand, when the temperature of the oil is low, it is difficult for the oil flowing through the oil return passage 120 to pass through the mesh structure portion 133.

The effect of this embodiment will be described.
(2-1) When the oil passes through the mesh structure portion 133, heat exchange between the cooling water and the oil can be promoted as in the cylinder block 10 of the first embodiment.

(2-2) Since the oil is guided so as to pass through the mesh structure portion 133 when the temperature of the oil is high, heat exchange between the cooling water and the oil is promoted, and the temperature of the oil tends to decrease. When the temperature of the oil is low, the oil is not guided toward the mesh structure portion 133, so that heat exchange is less likely to be promoted and the temperature of the oil is likely to rise. That is, the efficiency of heat exchange can be changed according to the temperature of the oil.

The first embodiment and the second embodiment can be modified and implemented as follows. The first embodiment, the second embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.

-In the first embodiment, the second mesh structure portion 32 is arranged in the second passage 22. If the first mesh structure portion 31 is provided in the first passage 21, the second mesh structure portion 32 may not be provided in the second passage 22.

-In the second embodiment, the mesh structure portion 133 provides a mesh only in a part of the oil return passage 120. A low-density mesh structure portion that forms a coarser mesh than the mesh structure portion 133 may be arranged around the mesh structure portion 133.

-In the second embodiment, the first guide plate 123 and the second guide plate 124 formed of bimetal are adopted. If the guide plate guides the oil so that it passes through the mesh structure portion 133 when the oil temperature is high and does not pass through the mesh structure portion 133 when the oil temperature is low, the second above. It has the same effect as that of the embodiment. Therefore, the guide plate for guiding the oil is not limited to the guide plate formed of bimetal, and a guide plate that can be controlled so as to move according to the temperature of the oil can also be adopted.

-In the second embodiment, the positions of the first guide plate 123, the second guide plate 124, and the mesh structure portion 133 can be changed. The first guide plate 123, at a position where the oil is guided so as to pass through the mesh structure portion 133 when the oil temperature is high, and the oil is guided so as not to pass through the mesh structure portion 133 when the oil temperature is low. The second guide plate 124 and the mesh structure portion 133 may be arranged.

-In each of the above embodiments, the distance between the crosslinks and the thickness of the crosslinks in each network structure can be changed as appropriate. By changing the roughness of the mesh in the mesh structure, the magnitude of the resistance when the oil passes through the mesh structure can be adjusted. For example, when using a high-viscosity type of oil, the mesh is coarsened, and when using a low-viscosity type of oil, the mesh is fine, and so on. It is conceivable to adjust.

-In each of the above embodiments, steel wool and wire mesh are exemplified as materials for the mesh structure portion that divides the inside of the oil return passage into a mesh shape. The material for forming the mesh structure is not limited to steel wool and wire mesh. A material having a large heat transfer coefficient and high heat conduction characteristics can be used as a material for a network structure portion that divides the inside of the oil return passage into a network by a plurality of crosslinks in different directions.

-In each of the above embodiments, a mesh structure is formed in the oil return passage by filling with steel wool or accommodating a wire mesh. A mesh structure can also be formed by dividing the inside of the oil return passage into a mesh by a plurality of crosslinks integrally molded with the wall for partitioning the oil return passage. A cylinder block in which a plurality of bridges are integrally molded with a wall that partitions an oil return passage can be formed, for example, by an additional manufacturing technique. As an additional manufacturing technique, there is a method of forming a three-dimensional structure by melting and laminating the metal powder by irradiating the metal powder with a laser.

-The shape of the oil return passage in each of the above embodiments is an example. For example, the first passage 21 in the first embodiment may be partitioned so as to be narrower toward the oil pan 91 side.

-In each of the above embodiments, the in-line 4-cylinder internal combustion engine 90 has been illustrated, but the number of cylinders and the arrangement of cylinders of the internal combustion engine are not limited to this. In the cylinder block constituting the internal combustion engine, the oil return passage may be formed at a position where the water jacket is sandwiched between the oil return passage and the cylinder bore. For example, it can be applied to an in-line 3-cylinder internal combustion engine or a V-type 6-cylinder internal combustion engine.

10 ... Cylinder block, 11 ... Deck surface, 12 ... Cylinder bore, 13 ... Water jacket, 14 ... Bolt hole, 20 ... Oil return passage, 21 ... 1st passage, 22 ... 2nd passage, 31 ... 1st mesh structure, 32 ... 2nd mesh structure, 41 ... Spacer, 90 ... Internal combustion engine, 91 ... Oil pan, 92 ... Cylinder head, 93A-93D ... 1st to 4th head passages, 94 ... Cylinder head cover, 110 ... Cylinder block, 120 ... Oil return passage, 123 ... First guide plate, 124 ... Second guide plate, 133 ... Mesh structure part.

Claims (1)

A cylinder block with a cylinder head attached to the top and an oil pan attached to the bottom to form an internal combustion engine.
With multiple cylinder bores
A water jacket arranged so as to surround the plurality of cylinder bores,
An oil return passage for returning the oil in the cylinder head to the oil pan is provided.
The oil return passage is formed at a position where the water jacket is sandwiched between the oil return passage and the cylinder bore, and has a mesh structure portion which is divided into a mesh by a plurality of crosslinks having different directions.
The mesh structure is a cylinder block provided in a region of the oil return passage through which oil passes in a high temperature state.

Images