Engine oil passage structure

Abstract

To efficiently cool the oil without making the oil return passage excessively large. [Solution] In the oil return passage 50 that returns the oil L that lubricates the lubricated part A of the cylinder head 20 to the oil pan 30 via the cylinder head and cylinder block 10, the block passage 60 has a larger passage cross-sectional area S than the head passage 70. The block surface 90 of the cylinder block and the head surface 100 of the cylinder head are joined to each other via a gasket 80. The head surface includes a sealing surface 101 that overlaps the block surface via the gasket, and a non-sealing surface 102 that is located on the oil return passage side of the sealing surface and does not overlap the block surface. The gasket includes a sealing portion 81 located between the sealing surface and the block surface, and a guide portion 84 located in the opening 85 through which the oil return passage passes and which guides the oil flowing from the head passage into the block passage to the block passage wall 61 of the block passage.

Description

Technical Field

[0001] The present disclosure relates to an oil passage structure of an engine.

Background Art

[0002] Generally, an engine is formed with an oil return passage as an oil passage structure. The oil return passage is for returning the oil that has lubricated the lubricated portion of the cylinder head to the oil pan through the cylinder head and the cylinder block.

[0003] The engine according to Patent Document 1 includes a cylinder head provided with a plurality of oil return passages, and a cylinder block provided with an oil return space in which the oil return passages of the cylinder head merge so as to be disposed below the cylinder head and face the water jacket. In this engine, among the open ends on the cylinder block side of the oil return passages of the cylinder head, the side facing the water jacket is formed in a shape approaching the water jacket.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In order to efficiently cool the oil after lubricating the lubricated portion of the cylinder head, it is important to increase the contact area of the oil flowing through the oil return passage with respect to the cylinder block. A simple method to achieve this is to increase the passage cross-sectional area of the return passage on the cylinder block side.

[0006] However, there are numerous obstructions around the oil return passage on the cylinder block side. Also, the space between the cylinder block and the cylinder head is sealed by a gasket. Simply increasing the cross-sectional area of ​​the oil return passage on the cylinder block side may cause interference with the surrounding obstructions or reduce the sealing performance due to the decrease in the sealing area provided by the gasket.

[0007] In other words, the method of efficiently cooling the oil by excessively increasing the cross-sectional area of ​​the oil return passage on the cylinder block side is difficult from a layout perspective.

[0008] The purpose of this disclosure is to efficiently cool the oil without making the oil return passage on the cylinder block side excessively large. [Means for solving the problem]

[0009] The engine oil passage structure according to this disclosure comprises a cylinder block in which a cylinder housing a piston is formed, a cylinder head that together with the cylinder and the piston forms a combustion chamber, an oil pan for storing oil, and a sheet-like gasket that seals the space between the cylinder block and the cylinder head, wherein the cylinder head and the cylinder block have an oil return passage for returning the oil that has lubricated the lubricated portion of the cylinder head back to the oil pan via the cylinder head and the cylinder block, and the oil return passage comprises a block passage formed in the cylinder block and a head passage formed in the cylinder head, and the block passage is the The block surface of the cylinder block facing the cylinder head and the head surface of the cylinder head facing the cylinder block are joined to each other via the gasket, with a larger cross-sectional area than the head passage. The head surface includes a sealing surface that overlaps the block surface via the gasket and a non-sealing surface that is located on the oil return passage side of the sealing surface and does not overlap the block surface. The gasket includes a sealing portion positioned between the sealing surface and the block surface and a guide portion positioned in an opening for the oil return passage. The guide portion guides the oil flowing from the head passage into the block passage to the block passage wall of the block passage.

[0010] In the oil return passage, the block passage formed in the cylinder block has a larger cross-sectional area than the head passage formed in the cylinder head. The head surface of the cylinder head includes a sealing surface that overlaps the block surface of the cylinder block via a gasket, and a non-sealing surface that is located on the oil return passage side of the sealing surface and does not overlap the block surface of the cylinder block. The gasket includes a sealing portion positioned between the sealing surface and the block surface of the head surface, and a guide portion positioned in the opening for the oil return passage.

[0011] The gasket's guide portion directs the oil flowing from the head passage into the block passage to the block passage wall. The oil guided by the gasket's guide portion makes it easier for the oil to come into contact with the block passage wall. This increases the contact area between the oil flowing through the block passage and the cylinder block. This allows for more efficient cooling of the oil after it has lubricated the lubricated parts of the cylinder head.

[0012] This allows for efficient oil cooling without excessively enlarging the block passage, which is the oil return passage on the cylinder block side.

[0013] In an engine oil passage structure according to one embodiment, the gasket includes an annular portion that is positioned in the opening and extends in an annular shape along the head passage wall of the head passage, the guide portion protrudes from the annular portion toward the seal portion side and toward the cylinder block side, and at least the tip of the guide portion faces the non-seal surface.

[0014] The guide section can be easily formed.

[0015] In an engine oil passage structure according to one embodiment, the annular portion has the same diameter as or a larger diameter than the head passage, both the tip and base end of the guide portion face the non-sealing surface, and the oil is guided by the surface of the guide portion located on the cylinder block side.

[0016] The annular portion is not exposed to the head passage. This prevents oil flowing from the head passage into the block passage from contacting the annular portion.

[0017] In an engine oil passage structure according to one embodiment, the annular portion has a smaller diameter than the head passage, the tip of the guide portion faces the non-sealing surface, the base end of the guide portion does not face the non-sealing surface, and the oil is guided by the surface of the guide portion that is located on the cylinder head side.

[0018] Depending on the weight of the oil flowing from the head passage into the block passage, the guide portion can be bent so as to project from the annular portion toward the seal portion side and the cylinder block side.

[0019] In the oil passage structure of the engine according to one embodiment, the gasket includes a connecting portion that connects the seal portion and the annular portion, and the guide portion and the connecting portion are at different positions in the circumferential direction of the annular portion.

[0020] The connecting portion for connecting the seal portion and the annular portion can be arranged at a position where it does not interfere with the guide portion.

[0021] In the oil passage structure of the engine according to one embodiment, the gasket includes a plurality of the guide portions arranged side by side in the circumferential direction of the annular portion.

[0022] The oil can be evenly guided over the circumferential direction with respect to the block passage wall of the block passage by a plurality of guide portions arranged side by side in the circumferential direction of the annular portion.

Advantages of the Invention

[0023] According to the present disclosure, the oil can be efficiently cooled without making the oil return passage on the cylinder block side excessively large.

Brief Description of the Drawings

[0024] [Figure 1] FIG. 1 shows a cross-sectional view of the engine according to the first embodiment taken along line I-I in FIG. 3. [Figure 2] FIG. 2 shows a cross-sectional view of the engine according to the first embodiment taken along line II-II in FIG. 3. [Figure 3] FIG. 3 shows a cross-sectional view of the engine according to the first embodiment taken along line III-III in FIGS. 1 and 2. [Figure 4] FIG. 4 schematically shows the oil supply passage according to the first embodiment. [Figure 5] Figure 5 shows the oil return passage and gasket according to the first embodiment, as an enlarged view of section V in Figure 2 and a cross-sectional view along line V in Figure 7. [Figure 6] Figure 6 shows a cross-sectional view of the gasket according to the first embodiment along line VI in Figure 7. [Figure 7] Figure 7 shows the gasket according to the first embodiment, viewed from the direction of line VII in Figure 5. [Figure 8] Figure 8 is a diagram corresponding to Figure 5 according to the second embodiment, showing the gasket in a cross-sectional view. [Figure 9] Figure 9 is a diagram corresponding to Figure 5 according to the third embodiment, and the gasket is shown in a cross-sectional view along line IX in Figure 10. [Figure 10] Figure 10 is a diagram corresponding to Figure 7 according to the third embodiment, and the gasket is shown in the view along the X-ray arrow in Figure 9. [Modes for carrying out the invention]

[0025] Embodiments of the present disclosure will be described in detail below with reference to the drawings. The following description of preferred embodiments is illustrative in nature and is not intended to limit the present disclosure, its applications, or its uses in any way.

[0026] <First Embodiment> The oil passage structure of the engine 1 according to the first embodiment will be described.

[0027] (engine) Figure 1 shows a cross-sectional view of engine 1 along line II in Figure 3. Figure 2 shows a cross-sectional view of engine 1 along line II-II in Figure 3. Figure 3 shows a cross-sectional view of engine 1 along line III-III in Figures 1 and 2.

[0028] Engine 1 is mounted in the vehicle. As shown in Figures 1-3, engine 1 comprises a cylinder block 10, a cylinder head 20, an oil pan 30, and a gasket 80. The oil passage structure of engine 1 includes an oil supply passage 40 and an oil return passage 50.

[0029] As shown in Figure 1, the cylinder block 10 has a plurality of cylinders 11 formed therein. The cylinders 11 are cylindrical and extend in the vertical direction. The plurality of cylinders 11 are arranged in a row in the cylinder row direction. The vertical direction may be straight with respect to the vertical direction or diagonally with respect to the vertical direction (in this example, it is diagonally extended). The cylinder row direction intersects the vertical direction. The cylinder row direction extends in the horizontal direction.

[0030] The cylinder 11 houses the piston 12. The piston 12 is columnar and extends vertically coaxially with the cylinder 11. The piston 12 reciprocates vertically within the cylinder 11.

[0031] A crank chamber 13 is formed below the cylinder 11 (piston 12) in the cylinder block 10. A crankshaft 14 is located in the crank chamber 13. The crankshaft 14 extends in the direction of the cylinder row and is rotatably supported relative to the cylinder block 10.

[0032] The piston 12 and the crankshaft 14 are connected by a connecting rod 15. When the piston 12 reciprocates within the cylinder 11, the crankshaft 14 rotates.

[0033] As shown in Figures 2 and 3, the cylinder block 10 is provided with a block-side jacket 16. Cooling water (coolant) flows through the block-side jacket 16. The block-side jacket 16 extends in the direction of the cylinder row. The block-side jacket 16 is provided on both outer sides of the cylinders 11 in the width direction (hereinafter simply referred to as the "width direction") perpendicular to the direction of the cylinder row. The block-side jacket 16 collectively surrounds the outer circumference of multiple cylinders 11.

[0034] As shown in Figure 1, the cylinder head 20 is located on the upper part of the cylinder block 10. The cylinder head 20 is positioned on the upper side of the cylinder block 10. The cylinder head 20, together with the cylinder 11 and the piston 12, forms the combustion chamber 21. The combustion chamber 21 is formed above the piston 12. The combustion chamber 21 is formed by the cylinder 11, the piston 12 and the cylinder head 20.

[0035] The cylinder head 20 is divided into upper and lower sections by a middle deck 20a. The middle deck 20a extends horizontally.

[0036] In the cylinder head 20, intake ports 22 and exhaust ports 23 are provided below the middle deck 20a. For example, two intake ports 22 and two exhaust ports 23 are provided for each cylinder 11. In the width direction, the intake ports 22 are located on one side of the combustion chamber 21 (hereinafter sometimes referred to as the "intake side"), and the exhaust ports 23 are located on the other side of the combustion chamber 21 (hereinafter sometimes referred to as the "exhaust side"). Intake air is drawn from the intake pipe into the combustion chamber 21 through the intake ports 22. Exhaust gas is discharged from the combustion chamber 21 into the exhaust pipe through the exhaust ports 23.

[0037] The cylinder head 20 is provided with an intake valve 24 and an exhaust valve 25. The intake valve 24 opens and closes the intake port 22. The exhaust valve 25 opens and closes the exhaust port 23.

[0038] The cylinder head 20 is equipped with an intake camshaft 26 and an exhaust camshaft 27. The intake camshaft 26 drives the intake valve 24. The exhaust camshaft 27 drives the exhaust valve 25. The intake camshaft 26 and the exhaust camshaft 27 are connected to the crankshaft 14. When the crankshaft 14 rotates, the intake camshaft 26 and the exhaust camshaft 27 are driven at a predetermined timing, causing the intake valve 24 and the exhaust valve 25 to open and close the intake port 22 and the exhaust port 23.

[0039] As shown in Figures 1 and 2, the cylinder head 20 is provided with a head-side jacket 28. Cooling water (coolant) flows through the head-side jacket 28. The head-side jacket 28 is formed between the intake port 22 and the exhaust port 23 and above the combustion chamber 21. The head-side jacket 28 extends in the direction of the cylinder row so as to correspond to the block-side jacket 16.

[0040] As shown in Figure 2, the block-side jacket 16 and the head-side jacket 28 are in communication with each other. Cooling water flows between the block-side jacket 16 and the head-side jacket 28.

[0041] As shown in Figure 1, the oil pan 30 is located at the bottom of the cylinder block 10. The oil pan 30 is positioned on the underside of the cylinder block 10. The oil pan 30 is box-shaped with an open top. The oil pan 30 stores oil L.

[0042] The gasket 80, the oil supply passage 40, and the oil return passage 50 will be described later.

[0043] (oil) The cylinder 11, piston 12, crankshaft 14, intake camshaft 26, and exhaust camshaft 27 constitute the lubricated part A of the engine 1. The oil L is there to lubricate the lubricated part A of the engine 1. The cylinder 11, piston 12, and crankshaft 14 constitute the block-side lubricated part A1, which is the lubricated part A of the cylinder block 10. The intake camshaft 26 and exhaust camshaft 27 constitute the head-side lubricated part A2, which is the lubricated part A of the cylinder head 20.

[0044] (Oil supply passage) Figure 4 shows a schematic diagram of the oil supply passage 40. The oil supply passage 40 supplies oil L to the lubricated part A. The oil supply passage 40 is provided in the cylinder block 10, the cylinder head 20, and the oil pan 30.

[0045] The oil supply passage 40 includes an oil pump 41, an oil filter 42, an oil cooler 43, a pan-side supply oil passage 44, a block-side supply oil passage 45, a head-side supply oil passage 46, a first connecting passage 47, and a second connecting passage 48.

[0046] The oil pump 41 is located inside the oil pan 30 (see Figure 1) and draws up the oil L stored in the oil pan 30. The oil filter 42 is located outside the oil pan 30 (specifically, on the exhaust side in the width direction relative to the oil pan 30, see Figure 1) and filters the oil L discharged from the oil pump 41. The oil cooler 43 is located outside the oil pan 30 (specifically, on the exhaust side in the width direction relative to the oil pan 30, see Figure 1) and cools the oil L discharged from the oil pump 41.

[0047] The pan-side supply oil passage 44 is located inside the oil pan 30 and on the outer wall of the oil pan 30. The pan-side supply oil passage 44 includes an oil passage connecting the oil pump 41 and the oil filter 42, and an oil passage connecting the oil filter 42 and the oil cooler 43.

[0048] The block-side supply oil passage 45 is located in the cylinder block 10. The block-side supply oil passage 45 includes a main gallery 45a, a number of branch oil passages 45b, and connecting oil passages 45c.

[0049] The main gallery 45a extends from the cylinder block 10 in the direction of the cylinder row. The main gallery 45a is positioned on the exhaust side in the width direction of the cylinder 11 and near the lower end of the cylinder 11 (see Figure 1).

[0050] The branched oil passages 45b branch off from the main gallery 45a and extend downward. Multiple branched oil passages 45b are arranged in a row with spacing in the direction of the cylinder row. Each branched oil passage 45b corresponds to each cylinder 11. The lower end of each branched oil passage 45b communicates with the bearing section 13a (see Figure 2) for supporting the crankshaft 14 in the crank chamber 13. The oil L that flows from the branched oil passage 45b to the bearing section 13a lubricates the crankshaft 14 (and the bearing section 13a).

[0051] The connecting oil passage 45c branches off from one end of the main gallery 45a in the cylinder row direction and extends to the intake side in the width direction.

[0052] The head-side supply oil passage 46 is located in the cylinder head 20. The head-side supply oil passage 46 has a head-side first oil passage 46a, two head-side second oil passages 46b, a head-side gallery 46c, and a plurality of head-side branch oil passages 46d.

[0053] The head-side first oil passage 46a extends in the width direction. The head-side second oil passage 46b branches off from the head-side first oil passage 46a and extends upward. The two head-side second oil passages 46b are spaced apart in the width direction, with one provided on the intake side and one on the exhaust side.

[0054] The head-side gallery 46c is connected to the head-side second oil passage 46b midway and extends in the direction of the cylinder row.

[0055] The head-side branch oil passages 46d branch off from the head-side gallery 46c and extend downward. Multiple head-side branch oil passages 46d are arranged in a row with spacing between them in the direction of the cylinder row. Each head-side branch oil passage 46d corresponds to each cylinder 11. The intake-side head-side branch oil passage 46d communicates with the bearing portion for supporting the intake camshaft 26. The exhaust-side head-side branch oil passage 46d communicates with the bearing portion for supporting the exhaust camshaft 27. The oil L that flows out from the head-side branch oil passages 46d to each bearing portion lubricates the intake camshaft 26 (and its bearing portion) and the exhaust camshaft 27 (and its bearing portion).

[0056] The first connecting passage 47 extends in the vertical direction. The first connecting passage 47 connects the pan-side supply oil passage 44 and the main gallery 45a of the block-side supply oil passage 45, and also connects the two. The second connecting passage 48 extends in the vertical direction. The second connecting passage 48 connects the connecting oil passage 45c of the block-side supply oil passage 45 and the head-side first oil passage 46a of the head-side supply oil passage 46, and also connects the two.

[0057] Although not shown in the diagram, the oil supply passage 40 further includes an oil passage that supplies oil L to an oil jet or the like for lubricating and cooling the piston 12 (and cylinder 11).

[0058] (Oil return passage) As shown in Figure 2, the oil return passage 50 is formed in the cylinder head 20 and the cylinder block 10. The oil return passage 50 is there to return the oil L that has lubricated the head-side lubricated parts A2 (intake camshaft 26 and exhaust camshaft 27) of the cylinder head 20 to the oil pan 30 via the cylinder head 20 and the cylinder block 10.

[0059] As shown in Figures 2 and 3, there are multiple oil return passages 50, corresponding to multiple cylinders 11. The multiple oil return passages 50 are arranged in a line in the direction of the cylinder row. The oil return passages 50 extend in the vertical direction.

[0060] The oil return passages 50 are provided one on the intake side and one on the exhaust side, between two adjacent cylinders 11 in the cylinder direction, and outside the cylinder row direction of the cylinders 11 located at both ends of the cylinder row direction.

[0061] The intake side oil return passage 50 and the exhaust side oil return passage 50 are located on the outer sides of the cylinder 11 in the width direction. The oil return passage 50 is located further out in the width direction than the block side jacket 16 and the head side jacket 28. The oil return passage 50 is located close to the block side jacket 16 and the head side jacket 28.

[0062] Here, the cylinder block 10 and the cylinder head 20 are connected by bolts (not shown). The cylinder block 10 is provided with block-side bolt holes 17 for passing the bolts through. The cylinder head 20 is provided with head-side bolt holes 29 for passing the bolts through.

[0063] The oil return passage 50 is located outside the width direction of the block-side bolt holes 17 and the head-side bolt holes 29. The oil return passage 50 is located near the block-side bolt holes 17 and the head-side bolt holes 29.

[0064] Figure 5 shows the oil return passage 50 as an enlarged view of section V in Figure 2. As shown in Figures 2, 3 and 5, the oil return passage 50 includes a block passage 60 and a head passage 70.

[0065] The block passage 60 is formed in the cylinder block 10. The block passage 60 extends in the vertical direction. When viewed in the vertical direction, the cross-section of the block passage 60 includes one large circle and two smaller circles connected to the outer circumference of the large circle. Although not shown, the lower end of the block passage 60 communicates with the oil pan 30. A block passage wall 61 is formed on the inner circumference of the block passage 60.

[0066] The head passage 70 is formed in the cylinder head 20. The head passage 70 extends in the vertical direction. The cross-section of the head passage 70 is approximately circular when viewed in the vertical direction. Although not shown, the upper end of the head passage 70 communicates with the head-side lubricated portion A2 of the cylinder head 20. A head passage wall 71 is formed on the inner circumference of the head passage 70.

[0067] After lubricating the head-side lubricated portion A2 of the cylinder head 20, the oil L first flows into the head passage 70 of the oil return passage 50, then into the block passage 60 of the oil return passage 50, and finally returns to the oil pan 30. Since the oil return passage 50 extends vertically, the oil L falls from above to below due to gravity.

[0068] The block passage 60 has a larger cross-sectional area S than the head passage 70. The cross-sectional area S is the area of ​​the cross section perpendicular to the flow direction of the oil return passage 50. The block passage cross-sectional area S1 of the block passage 60 is larger than the head passage cross-sectional area S2 of the head passage 70. A step G is formed between the block passage wall 61 of the block passage 60 and the head passage wall 71 of the head passage 70.

[0069] As shown in Figure 5, the cylinder block 10 has a block surface 90. The block surface 90 is the upper surface facing upwards. The cylinder head 20 has a head surface 100. The head surface 100 is the lower surface facing downwards.

[0070] The block surface 90 of the cylinder block 10 faces the cylinder head 20. The head surface 100 of the cylinder head 20 faces the cylinder block 10. The cylinder head 20 side is the upper side. The cylinder block 10 side is the lower side.

[0071] The upper end of the block passage 60 is provided on the block surface 90. The lower end of the head passage 70 is provided on the head surface 100. As described above, in the oil return passage 50, a step G is formed between the block passage wall 61 of the block passage 60 and the head passage wall 71 of the head passage 70. Correspondingly, the head surface 100 protrudes toward the oil return passage 50 side relative to the block surface 90. Here, the oil return passage 50 side means the side closer to the oil return passage 50. In the example in Figure 5, the oil return passage 50 side is the right side of Figure 5.

[0072] As mentioned above, the cylinder head 20 tends to get hotter than the cylinder block 10 because of the presence of the combustion chamber 21. Conversely, the cylinder block 10 tends to get colder than the cylinder head 20.

[0073] Therefore, in order to efficiently cool the oil L after it has lubricated the head-side lubricated parts A2 of the cylinder head 20 (intake camshaft 26 and exhaust camshaft 27), it is important to increase the contact area of ​​the oil L flowing through the oil return passage 50 with the cylinder block 10. Specifically, increasing the cross-sectional area S of the block passage 60 (which is the oil return passage 50 on the cylinder block 10 side) is effective in efficiently cooling the oil L.

[0074] However, there are numerous obstructions around the block passage 60 (for example, the block-side jacket 16 and the block-side bolt holes 17). Also, the space between the cylinder block 10 and the cylinder head 20 is sealed by a gasket 80. If the passage cross-sectional area S of the block passage 60 is simply increased, there is a risk of interference with the surrounding obstructions or a decrease in sealing performance due to the reduction in the sealing area provided by the gasket 80.

[0075] In other words, the method of efficiently cooling the oil L by excessively increasing the cross-sectional area of ​​the block passage 60 is difficult from a layout standpoint.

[0076] In this embodiment, by implementing the improvements described later, it is possible to efficiently cool the oil L without making the block passage 60 (which is the oil return passage 50 on the cylinder block 10 side) excessively large.

[0077] (gasket) Figure 5 shows a cross-sectional view of gasket 80 along line V in Figure 7. Figure 6 shows a cross-sectional view of gasket 80 along line VI in Figure 7. Figure 7 shows a view of gasket 80 along line VII in Figure 5.

[0078] As shown in Figures 5-7, the gasket 80 is in sheet form. The gasket 80 has its thickness in the vertical direction and extends horizontally. The gasket 80 is positioned between the cylinder block 10 and the cylinder head 20. The gasket 80 provides a liquid-tight seal between the cylinder block 10 and the cylinder head 20.

[0079] Specifically, the gasket 80 is interposed between the block surface 90 of the cylinder block 10 and the head surface 100 of the cylinder head 20. The block surface 90 of the cylinder block 10 and the head surface 100 of the cylinder head 20 are joined to each other via the gasket 80.

[0080] A portion of the gasket 80 is positioned across the entire head surface 100. Here, the head surface 100 protrudes toward the oil return passage 50 relative to the block surface 90. Therefore, a portion of the gasket 80 protrudes toward the oil return passage 50 relative to the block surface 90.

[0081] As shown in Figures 5 and 6, the head surface 100 includes a sealing surface 101 and a non-sealing surface 102. The sealing surface 101 overlaps the block surface 90 (viewed vertically) via the gasket 80. The sealing function of the gasket 80 is performed on the sealing surface 101.

[0082] The non-sealing surface 102 is located on the oil return passage 50 side of the sealing surface 101. The non-sealing surface 102 does not overlap with the block surface 90 (when viewed in the vertical direction). The sealing function of the gasket 80 is not performed on the non-sealing surface 102.

[0083] As shown in Figures 5-7, the gasket 80 includes a sealing portion 81, an annular portion 82, a plurality of connecting portions 83, and a plurality of guide portions 84. The gasket 80 includes an upper surface 80a facing upward and a lower surface 80b facing downward. The upper surface 80a is the surface of the gasket 80 that is located on the cylinder head 20 side. The lower surface 80b is the surface of the gasket 80 that is located on the cylinder block 10 side.

[0084] The sealing portion 81 of the gasket 80 is positioned between the sealing surface 101 of the head surface 100 and the block surface 90. The upper surface 80a of the sealing portion 81 of the gasket 80 faces the sealing surface 101 of the head surface 100. The lower surface 80b of the sealing portion 81 of the gasket 80 faces the block surface 90.

[0085] The gasket 80 is provided with an opening 85. The opening 85 penetrates the gasket 80 in the vertical direction (thickness direction). The opening 85 is there for the oil return passage 50 to pass through. In the gasket 80, the opening 85 is positioned on the oil return passage 50 side of the seal portion 81.

[0086] The cross-sectional shape and size of the opening 85 correspond to the block passage 60 and are the same as the cross-sectional shape and size of the block passage 60. The cross-sectional shape of the opening 85, like the cross-sectional shape of the block passage 60, includes one large circle and two smaller circles connected to the outer circumference of the large circle when viewed in the vertical direction. The edge 85a of the opening 85 extends along the block passage wall 61 of the block passage 60. The edge 85a constitutes the inner circumference of the opening 85.

[0087] In the gasket 80, the annular portion 82 is positioned in the opening 85. That is, in the gasket 80, the annular portion 82 (positioned in the opening 85) is positioned on the oil return passage 50 side of the seal portion 81. More specifically, in the gasket 80, the annular portion 82 is positioned on the inner (circumferential) side of the edge 85a of the opening 85.

[0088] The cross-sectional shape and size of the annular portion 82 correspond to the head passage 70 and are the same as the cross-sectional shape and size of the head passage 70. The cross-section of the annular portion 82 is approximately circular when viewed in the vertical direction, similar to the cross-section of the head passage 70. The annular portion 82 extends around its entire circumference.

[0089] The annular portion 82 is annular when viewed in the vertical direction. The annular portion 82 extends in an annular shape along the head passage wall 71 of the head passage 70 when viewed in the vertical direction. Hereinafter, the direction in which the annular portion 82 extends will be referred to as the circumferential direction θ.

[0090] The annular portion 82 is positioned concentrically with the head passage 70. The annular portion 82 has the same diameter as the head passage 70. Specifically, the inner diameter d of the annular portion 82 is equal to the inner diameter d0 of the head passage 70. The annular portion 82 is positioned on the non-sealing surface 102 of the head surface 100. The upper surface 80a of the annular portion 82 faces the non-sealing surface 102 of the head surface 100. The upper surface 80a of the annular portion 82 does not face the head passage 70. The annular portion 82 is not exposed to the head passage 70.

[0091] In the gasket 80, the connecting portion 83 is located in the opening 85. That is, in the gasket 80, the connecting portion 83 (located in the opening 85) is located on the oil return passage 50 side of the sealing portion 81. More specifically, in the gasket 80, the connecting portion 83 is located on the inner (circumferential) side of the edge 85a of the opening 85. Also, in the gasket 80, the connecting portion 83 is located on the outer (circumferential) side of the annular portion 82.

[0092] The connecting portion 83 extends between the sealing portion 81 and the annular portion 82 in the opening 85. The connecting portion 83 connects the sealing portion 81 and the annular portion 82.

[0093] Multiple connecting portions 83 are arranged side by side with spacing between them in the circumferential direction θ of the annular portion 82.

[0094] In the gasket 80, the guide portion 84 is positioned in the opening 85. That is, in the gasket 80, the guide portion 84 (positioned in the opening 85) is positioned on the oil return passage 50 side of the seal portion 81. More specifically, in the gasket 80, the guide portion 84 is positioned on the inner (circumferential) side of the edge 85a of the opening 85. Also, in the gasket 80, the guide portion 84 is positioned on the outer (circumferential) side of the annular portion 82.

[0095] Multiple guide sections 84 are arranged side by side with spacing between them in the circumferential direction θ of the annular section 82. The guide sections 84 and the connecting section 83 are located at different positions in the circumferential direction θ of the annular section 82.

[0096] The guide portion 84 protrudes diagonally downward from the annular portion 82 in the opening 85. The guide portion 84 protrudes from the annular portion 82 toward the seal portion 81 and the cylinder block 10. The guide portion 84 is bent diagonally downward from the annular portion 82 by hand, for example, during manufacturing.

[0097] At least the upper surface 80a of the tip portion 84a of the guide portion 84 faces the non-sealing surface 102 of the head surface 100. In this example, the upper surface 80a of the base portion 84b of the guide portion 84 also faces the non-sealing surface 102 of the head surface 100. The upper surfaces 80a of both the tip portion 84a and the base portion 84b of the guide portion 84 face the non-sealing surface 102 of the head surface 100. The entire upper surface 80a of the guide portion 84 faces the non-sealing surface 102 of the head surface 100. The tip portion 84a is the end of the guide portion 84 on the sealing portion 81 side. The base portion 84b is the end of the guide portion 84 on the annular portion 82 side.

[0098] As shown in Figure 5, the guide portion 84 guides the oil L flowing from the head passage 70 into the block passage 60 to the block passage wall 61 of the block passage 60. The oil L is guided to the block passage wall 61 of the block passage 60 by the lower surface 80b of the guide portion 84, which is located on the cylinder block 10 side.

[0099] (Effects and Benefits) In the oil return passage 50, the block passage 60 formed in the cylinder block 10 has a larger cross-sectional area S than the head passage 70 formed in the cylinder head 20. The head surface 100 of the cylinder head 20 includes a sealing surface 101 that overlaps with the block surface 90 of the cylinder block 10 via a gasket 80, and a non-sealing surface 102 that is located on the oil return passage 50 side of the sealing surface 101 and does not overlap with the block surface 90 of the cylinder block 10.

[0100] The gasket 80 includes a sealing portion 81 positioned between the sealing surface 101 of the head surface 100 and the block surface 90, and a guide portion 84 positioned in an opening 85 for the oil return passage 50 to pass through.

[0101] The guide portion 84 of the gasket 80 guides the oil L flowing from the head passage 70 into the block passage 60 to the block passage wall 61 of the block passage 60. The oil L guided by the guide portion 84 of the gasket 80 is more likely to come into contact with the block passage wall 61 of the block passage 60. In particular, the oil L is more likely to come into contact with the upper end of the block passage wall 61 of the block passage 60 (near the step G between the block passage wall 61 and the head passage wall 71).

[0102] The contact area of ​​the oil L flowing through the block passage 60 with the cylinder block 10 can be increased. Furthermore, the residence time of the oil L in the block passage 60 of the cylinder block 10 can be increased. Cooling water flows through the block-side jacket 16 of the cylinder block 10. Also, the cylinder block 10 tends to become colder than the cylinder head 20, where the combustion chamber 21 is located.

[0103] By increasing the contact area of ​​the oil L flowing through the block passage 60 with the cylinder block 10, the oil L can be cooled efficiently after lubricating the head-side lubricated portion A2 of the cylinder head 20.

[0104] The oil L can be efficiently cooled without making the block passage 60 (which is the oil return passage 50 on the cylinder block 10 side) excessively large.

[0105] Furthermore, the opening end of the block passage 60 on the block surface 90 does not need to be enlarged in diameter to guide the oil L.

[0106] Since the block passage 60 does not need to be made excessively large, interference between the block passage 60 and surrounding interfering objects (for example, the block-side jacket 16 or the block-side bolt holes 17) can be suppressed.

[0107] Furthermore, since the block passage 60 does not need to be made excessively large, the decrease in sealing performance due to the reduction in the sealing area by the gasket 80 can be suppressed.

[0108] The guide portion 84 is provided on the gasket 80, which is essential for sealing the space between the cylinder block 10 and the cylinder head 20. Since there is no need to provide a new component solely for the purpose of guiding the oil L flowing from the head passage 70 into the block passage 60 to the block passage wall 61 of the block passage 60, the increase in the number of parts can be suppressed.

[0109] The guide portion 84 protrudes from the annular portion 82 toward the seal portion 81 and the cylinder block 10. The guide portion 84 can be easily formed.

[0110] The annular portion 82 has the same diameter as the head passage 70. The annular portion 82 is not exposed to the head passage 70. This prevents the oil L flowing from the head passage 70 into the block passage 60 from coming into contact with the annular portion 82 (which would increase the resistance to oil flow).

[0111] The connecting portion 83 connects the sealing portion 81 and the annular portion 82. The guide portion 84 and the connecting portion 83 are located at different positions in the circumferential direction θ of the annular portion 82. The connecting portion 83 for connecting the sealing portion 81 and the annular portion 82 can be positioned so as not to interfere with the guide portion 84.

[0112] The oil L can be evenly guided along the circumferential direction θ of the block passage 60 to the block passage wall 61 by a plurality of guide portions 84 arranged in a line along the circumferential direction θ of the annular portion 82.

[0113] Applying the oil passage structure of the engine 1 according to this embodiment is particularly effective when the upper limit temperature of the oil L is low or when the oil L has low viscosity.

[0114] <Second Embodiment> The oil passage structure of the engine 1 according to the second embodiment will now be described. In the following description, components similar to those in the above embodiment will be denoted by the same reference numerals, and detailed descriptions will be omitted. Figure 8 is a diagram corresponding to Figure 5, and shows the gasket 80 in a cross-sectional view.

[0115] The annular portion 82 is positioned concentrically with the head passage 70. The annular portion 82 has a larger diameter than the head passage 70. Specifically, the inner diameter d of the annular portion 82 is larger than the inner diameter d0 of the head passage 70. The upper surface 80a of the annular portion 82 does not face the head passage 70. The annular portion 82 is not exposed to the head passage 70.

[0116] This prevents the oil L flowing from the head passage 70 into the block passage 60 from coming into contact with the annular portion 82 (which would increase the resistance to oil flow).

[0117] The other configurations are the same as in the first embodiment.

[0118] <Third Embodiment> The oil passage structure of the engine 1 according to the third embodiment will be described below. In the following description, components similar to those in the above embodiment will be denoted by the same reference numerals, and detailed descriptions will be omitted. Figure 9 is a diagram corresponding to Figure 5, and the gasket 80 is shown in a cross-sectional view along line IX in Figure 10. Figure 10 is a diagram corresponding to Figure 7, and the gasket 80 is shown in a view along line X in Figure 9.

[0119] The annular portion 82 is positioned concentrically with the head passage 70. The annular portion 82 has a smaller diameter than the head passage 70. Specifically, the inner diameter d of the annular portion 82 is smaller than the inner diameter d0 of the head passage 70. The upper surface 80a of the annular portion 82 does not face the non-sealing surface 102 of the head surface 100. The upper surface 80a of the annular portion 82 faces the head passage 70. The annular portion 82 is exposed to the head passage 70.

[0120] The guide portion 84 protrudes diagonally downward from the annular portion 82 at the opening 85. The guide portion 84 protrudes from the annular portion 82 toward the seal portion 81 side and toward the cylinder block 10 side.

[0121] The upper surface 80a of the tip portion 84a of the guide portion 84 faces the non-sealing surface 102 of the head surface 100. The upper surface 80a of the base portion 84b of the guide portion 84 does not face the non-sealing surface 102 of the head surface 100.

[0122] The guide section 84 guides the oil L flowing from the head passage 70 into the block passage 60 to the block passage wall 61 of the block passage 60. The oil L is guided to the block passage wall 61 of the block passage 60 by the upper surface 80a of the guide section 84, which is located on the cylinder head 20 side.

[0123] When oil L comes into contact with the upper surface 80a of the guide portion 84, the guide portion 84 is bent diagonally downward from the annular portion 82 by the weight of the oil L. The guide portion 84 is thinner compared to the first embodiment. By making the guide portion 84 thinner, it becomes easier to bend the guide portion 84 due to the weight of the oil L.

[0124] The weight of the oil L flowing from the head passage 70 into the block passage 60 causes the guide portion 84 to bend so that it protrudes diagonally downward from the annular portion 82 toward the seal portion 81 and the cylinder block 10.

[0125] The other configurations are the same as in the first embodiment.

[0126] <Other Embodiments> Although this disclosure has been described above with reference to preferred embodiments, this description is not limiting, and various modifications, substitutions, or combinations are, of course, possible.

[0127] In the third embodiment, the guide portion 84 may be bent diagonally downward from the annular portion 82 in advance during manufacturing (by manual work, etc.).

[0128] The annular portion 82 is not limited to a circular annular shape, but may also be a polygonal annular shape or a complex annular shape, for example.

[0129] The annular portion 82 does not necessarily extend around the entire circumference; it may have a break in the middle. Multiple parts of the gasket 80 may be combined to form the annular portion 82.

[0130] The oil return passage 50 may have a simple shape in which a large-diameter block passage 60 and a small-diameter head passage 70 are connected concentrically to each other. [Industrial applicability]

[0131] This disclosure is extremely useful and has high industrial applicability because it can be applied to engine oil passage structures. [Explanation of Symbols]

[0132] θ Circumferential direction L Oil A Lubricated part S Passage cross-sectional area 1 Engine 10 Cylinder Block 11 cylinders 12 pistons 21 Combustion chamber 30 oil pans 50 Oil return passage 60 Block Passage 61 Block passageway wall 70 Headway 71 Headway wall 80 Gasket 80a Top surface (side) 80b Bottom surface (side) 81 Seal part 82 Ring section 83 Connecting part 84 Guide section 84a Tip 84b Proximal end 85 Aperture 90 Block surface 100 Head surface 101 Sealing surface 102 Non-sealing surface

Claims

1. A cylinder block in which a cylinder housing a piston is formed, A cylinder head that, together with the cylinder and the piston, forms a combustion chamber, An oil pan for storing oil, A sheet-like gasket that seals the space between the cylinder block and the cylinder head is provided, The cylinder head and the cylinder block are provided with an oil return passage for returning the oil that has lubricated the lubricated portion of the cylinder head back to the oil pan via the cylinder head and the cylinder block. The aforementioned oil return passage is Block passage formed in the cylinder block, The cylinder head has a head passage formed in the cylinder head, The block passage has a larger cross-sectional area than the head passage. The block surface of the cylinder block facing the cylinder head and the head surface of the cylinder head facing the cylinder block are joined to each other via the gasket. The head surface includes a sealing surface that overlaps the block surface via the gasket, and a non-sealing surface that is located on the oil return passage side of the sealing surface and does not overlap the block surface. The aforementioned gasket is A sealing portion is disposed between the sealing surface and the block surface, Includes a guide portion positioned in an opening for the oil return passage, The guide portion is an engine oil passage structure that guides the oil flowing from the head passage into the block passage to the block passage wall of the block passage.

2. The gasket includes an annular portion that is positioned in the opening and extends in an annular shape along the wall of the head passage of the head passage, The guide portion protrudes from the annular portion toward the seal portion side and toward the cylinder block side, The engine oil passage structure according to claim 1, wherein at least the tip of the guide portion faces the non-sealing surface.

3. The annular portion has the same diameter as the head passage or a larger diameter than the head passage. Both the tip and base end of the guide portion face the non-sealing surface, The oil is guided by a surface of the guide portion located on the cylinder block side, as described in claim 2.

4. The annular portion has a smaller diameter than the head passage. The tip of the guide portion faces the non-sealing surface, The base end of the guide portion does not face the non-sealing surface. The oil is guided by the surface of the guide portion located on the cylinder head side, as described in claim 2.

5. The gasket includes a connecting portion that connects the sealing portion and the annular portion. The engine oil passage structure according to any one of claims 2 to 4, wherein the guide portion and the connecting portion are located at different positions in the circumferential direction of the annular portion.

6. The engine oil passage structure according to any one of claims 2 to 4, wherein the gasket includes a plurality of guide portions arranged side by side in the circumferential direction of the annular portion.

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