Internal combustion engine

Abstract

To suppress collision of oil returning from a cylinder head to an oil pan with a crankshaft.SOLUTION: An internal combustion engine includes: a wall provided on a side to which a transmission case is attached and having an oil dropping passage which allows oil supplied into a cylinder head to flow down; an oil seal retainer provided outside the wall, holding an oil seal attached around a crankshaft of the internal combustion engine, recessed to a side away from the wall, and forming a space communicating with the oil dropping passage between the wall and the same; and an oil pan provided below the wall, and having a guide part communicated with the space and introducing the oil into the inside at a position lower than a lower end of a rotation locus of the crankshaft.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to an internal combustion engine. [Background technology]

[0002] In an internal combustion engine, oil stored in an oil pan provided below a cylinder block is supplied to each part of the internal combustion engine by an oil pump. The oil supplied to each part of the internal combustion engine is returned to the oil pan again. The oil supplied to the cylinder head provided above the cylinder block is also returned to the oil pan via an oil return passage formed in the wall of the cylinder block. Here, the oil return passage is provided at a plurality of locations along the direction in which the crankshaft extends, but it is difficult to form an oil return passage at the end of the cylinder block on the transmission case mounting side. This is because, for example, a structure for mounting an oil seal housing is provided on the outer wall surface of the cylinder block on the transmission case mounting side, and the oil return passage must be formed avoiding this structure. For example, Patent Document 1 is an example of a document that aims to solve such a problem. Patent Document 1 discloses a structure in which an oil passage formed between a cylinder block and an oil seal housing is connected to an oil drop passage provided along the cylinder axial direction in a mounting flange on the transmission case side of the cylinder block. The oil seal housing is a part that holds the outer periphery of the oil seal that is attached around the crankshaft, and is sometimes called an oil seal retainer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2000-282827 A Summary of the Invention [Problem to be solved by the invention]

[0004] According to Patent Document 1, by providing an oil passage formed between the cylinder block and the oil seal housing, oil can be returned smoothly from the cylinder head to the oil pan. However, in the structure disclosed in Patent Document 1, the oil returned to the oil pan through the oil passage formed between the cylinder block and the oil seal housing is returned to the rotation trajectory of the crankshaft. If the oil is returned to the rotation trajectory of the crankshaft, for example, the rotation trajectory of the counterweight, there is a possibility that air bubbles will be generated in the oil stirred by the counterweight, or the oil that collides with the counterweight will turn into mist.

[0005] Therefore, an object of the invention disclosed in this specification is to suppress the collision of oil returning from the cylinder head to the oil pan with the crankshaft. [Means for solving the problem]

[0006] The internal combustion engine disclosed in this specification comprises a wall portion provided on the side of the internal combustion engine where a transmission case is attached, and in which an oil drop passage is formed to allow oil supplied into a cylinder head to flow downward, an oil seal retainer provided on the outside of the wall portion, holding an oil seal attached around a crankshaft provided in the internal combustion engine, and recessed on the side away from the wall portion to form a space between the wall portion and communicating with the oil drop passage, and an oil pan provided below the wall portion, below the lower end of the rotational trajectory of the crankshaft, and having a guide portion formed therein that communicates with the space and introduces the oil into the interior. Effect of the Invention

[0007] The invention disclosed in this specification can suppress the collision of oil returning from the cylinder head to the oil pan with the crankshaft. [Brief description of the drawings]

[0008] [Figure 1]FIG. 1 is a diagram showing an internal combustion engine according to an embodiment as viewed from the end side where a transmission case is attached. [Diagram 2] FIG. 2 is a diagram showing a state where an end portion of the internal combustion engine according to the embodiment to which a mission case is attached is viewed from a surface side along the direction in which the crankshaft extends. [Diagram 3] FIG. 3 is a perspective view of an oil seal retainer that is attached to the internal combustion engine of the embodiment. [Figure 4] FIG. 4 is a diagram showing the oil pan provided in the internal combustion engine of the embodiment as viewed from the end side where the transmission case is attached. [Diagram 5] FIG. 5 is a simplified cross-sectional view of the internal combustion engine according to the embodiment taken along line X1-X1 in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. However, in the drawings, the dimensions, ratios, etc. of each part may not be illustrated to be completely consistent with the actual ones. In addition, in some drawings, details may be omitted and the drawings may be simplified. Furthermore, the scale of each element depicted in each drawing may differ from one another.

[0010] A schematic configuration of an internal combustion engine 100 of this embodiment will be described with reference to the drawings. In the following description, the top, bottom, left and right directions of the internal combustion engine 100 are set as shown in Fig. 1, and the front-rear direction of the internal combustion engine 100 is set as shown in Fig. 2. For this reason, Fig. 1 shows the rear surface of the internal combustion engine 100. The rear surface of the internal combustion engine 100 is the surface to which a transmission case (not shown) is attached.

[0011] 1 and 2, an internal combustion engine 100 includes a cylinder block 1. A cylinder head 3 is provided above the cylinder block. An oil pan 5 is provided below the cylinder block 1 via a bed plate 4. The bed plate 4, together with the cylinder block 1, rotatably supports a crankshaft 6. The outer wall of the cylinder block 1 and the outer wall of the bed plate 4 form a wall 101 on the rear side of the internal combustion engine 100. A transmission case is attached to this wall 101 in the internal combustion engine 100. An oil dropping passage 2 that allows oil supplied to the cylinder head 3 to flow down toward the oil pan 5 is provided within the outer wall of the cylinder block 1 that forms the wall 101. An inlet 2a of the oil dropping passage 2 opens into the cylinder head 3. An outlet 2b of the oil dropping passage 2 opens to the wall 101.

[0012] A plurality of oil return passages for returning oil from the cylinder head 3 to the oil pan 5 are provided along the axial direction of the crankshaft (see FIG. 2), but this configuration itself is a conventionally known configuration. Therefore, in this specification, only the oil drop passage 2 provided near the rear surface of the internal combustion engine 100 will be described.

[0013] An oil seal retainer 7 is attached to the wall portion 101 as shown by an arrow 21 in FIG. 2. The oil seal retainer 7 is a component that holds the outer periphery of an oil seal (not shown) that is attached around the crankshaft 6. Here, the oil seal retainer 7 will be described in detail with reference to FIG. 3. FIG. 3 is a perspective view of the oil seal retainer 7 as seen from the surface side facing the wall portion 101. The oil seal retainer 7 has an annular inner wall portion 8. The inner wall portion 8 has a mating surface 8a that comes into close contact with the wall portion 101. The inner peripheral surface 8b of the inner wall portion 8 functions as an oil seal holding portion into which an oil seal is fitted. An outer wall portion 9 is provided on the outer peripheral edge of the oil seal retainer 7. The outer wall portion 9 has a mating surface 9a that comes into close contact with the wall portion 101. The outer wall portion 9 has bolt holes 9b for bolting the oil seal retainer 7 to the wall portion 101 at predetermined intervals in the circumferential direction.

[0014] The oil seal retainer 7 has an annular space 10 surrounded by an inner wall portion 8 and an outer wall portion 9. As shown in FIG. 2, the oil seal retainer 7 is attached to the wall portion 101 so that the outlet 2b of the oil dropping passage 2 opens into the space 10. As a result, the space 10 forms a part of a passage through which oil flows down between the wall portion 101 (the outer wall of the cylinder block 1 and the outer wall of the bed plate 4). In other words, the oil seal retainer 7 is recessed on the side away from the wall portion 101, and has a space 10 between the wall portion 101 and the oil seal retainer 7 that communicates with the oil dropping passage 2. The oil seal retainer 7 is attached to the wall portion 101 by bolts 11 as shown in FIG. 1.

[0015] The oil dropping passage 2 is formed in the wall 101, but since the wall 101 is provided with bolt holes (not shown) for bolting the oil seal retainer 7, it is difficult to extend the oil dropping passage 2 downward by avoiding the bolt holes. In this embodiment, the space 10 forms a part of the passage through which the oil flows, so that the oil can flow downward to the bottom of the cylinder block 1. Depending on the aspect of the internal combustion engine 100, a blind plug that seals a main oil gallery formed in the cylinder block 1 may be provided in the wall 101. This blind plug may also hinder the downward extension of the oil dropping passage. Even when such a blind plug is provided, the oil can be caused to flow downward to the bottom of the cylinder block 1 by flowing the oil into the space 10 provided in the oil seal retainer 7.

[0016] Next, the oil pan 5 will be described. Referring to FIG. 2, the oil pan 5 has a guide portion 5a on the upper edge portion continuous with the wall portion 101. Referring to FIG. 4, the guide portion 5a has a shape in which the upper edge portion of the oil pan 5 is hollowed out in an arc shape at the end surface continuous with the wall portion 101. The guide portion 5a has an inclined surface 5a1 that slopes downward toward the inside of the oil pan 5. As shown in FIG. 2, the oil seal retainer 7 is attached such that the space 10 covers the guide portion 5a at the end surface of the oil pan 5. This brings the space 10 and the guide portion 5a into communication with each other.

[0017] The oil stored in the oil pan 5 is supplied to each part of the internal combustion engine 100 through an oil gallery (not shown) by operation of an oil pump (not shown). The oil supplied to each part of the internal combustion engine 100 is returned to the oil pan 5 again and circulates within the internal combustion engine 100. When the oil supplied into the cylinder head 3 is returned to the oil pan 5, it flows into an oil return passage 2 provided in the cylinder block 1.

[0018] Here, the position where the guide portion 5a is provided will be described in more detail with reference to FIG. 5. FIG. 5 is a simplified cross-sectional view taken along line X1-X1 in FIG. 1. Referring to FIG. 5, the crankshaft 6 provided in the internal combustion engine 100 includes a crank arm 6a and a crank pin 6b held by the crank arm 6a. A connecting rod (not shown) is attached to the crank pin 6b. The crankshaft 6 includes a counterweight 6c protruding on the opposite side across the axis of the crankshaft 6. In FIG. 5, reference character LE indicates the lower end of the rotation trajectory of the counterweight 6c. The guide portion 5a is located below this lower end LE.

[0019] The oil in the cylinder head 3 flows from the inlet 2a into the oil dropping passage 2 as shown by arrow 22a in Fig. 5. The oil that has flowed into the oil dropping passage 2 flows down inside the oil dropping passage 2 as shown by arrow 22b, and is discharged into the space 10 from the outlet 2b as shown by arrow 22c. The oil that has been discharged into the space 10 flows down inside the oil seal retainer 7 as shown by arrow 22d. Then, as shown by arrow 22e, it flows into the oil pan 5 through the guide portion 5a. The oil that has flowed into the oil pan 5 flows down the inclined surface 5a1 as shown by arrow 22f, and reaches the inside of the oil pan 5 as shown by arrow 22g.

[0020] This prevents the oil introduced into the oil pan 5 through the guide portion 5a from contacting the crankshaft 6, more specifically, the counterweight 6c. As a result, the oil is prevented from being stirred by the counterweight 6c to generate air bubbles, and the oil that collides with the counterweight 6c is prevented from turning into mist.

[0021] In this embodiment, the end of the counterweight 6c is the farthest from the axis of the crankshaft 6. Therefore, the lower end LE of the rotation trajectory in this embodiment is the lower end of the rotation trajectory drawn by the end of the counterweight 6c. However, the lower end LE of the rotation trajectory is not limited to this, and is set appropriately according to the shape of the crankshaft 6. For example, when the end of the crank arm 6a is the farthest from the axis of the crankshaft 6, the lower end of the rotation trajectory drawn by the end of the crank arm 6a is the lower end LE. When any other part is the farthest from the axis of the crankshaft 6, the lower end of the rotation trajectory drawn by that part is set as the lower end LE.

[0022] In this embodiment, the bed plate 4 is provided below the cylinder block 1. This makes the distance of the area below the outlet 2b of the oil dropping passage 2 longer. This lowers the vertical position of the oil pan 5, ensuring a distance between the outlet 2b of the oil dropping passage 2 and the guide portion 5a of the oil pan 5. As a result, the guide portion 5a is located below the lower end LE of the rotation trajectory of the counterweight 6c. Here, instead of attaching the bed plate 4, the lower end of the cylinder block 1 may be extended downward. That is, the lower end of the cylinder block 1 may be extended and the oil pan 5 may be attached to the extended lower end. Even in this embodiment, the guide portion 5a can be positioned below the lower end LE of the rotation trajectory of the counterweight 6c, and thus the oil introduced into the oil pan 5 can be prevented from contacting the counterweight 6c.

[0023] According to this embodiment, the oil drop passage 2 is provided in the wall 101 on the side where the transmission case of the internal combustion engine 100 is attached, and the space 10 communicates with the oil drop passage 2. Furthermore, the oil pan 5 is provided with a guide portion 5a communicating with the space 10. This allows the oil to smoothly flow down from the cylinder head 3 to the oil pan 5 on the side where the transmission case of the internal combustion engine 100 is attached. Also, according to this embodiment, the position of the guide portion 5a is disposed below the lower end LE of the rotation trajectory of the crankshaft 6. This makes it possible to prevent the oil introduced into the oil pan 5 from contacting the counterweight 6c. As a result, it is possible to prevent air bubbles from being generated in the oil and the oil from becoming mist.

[0024] The above-described embodiments are merely examples for implementing the present invention, and the present invention is not limited to these. Various modifications of these embodiments are within the scope of the present invention. Furthermore, it is self-evident from the above description that various other embodiments are possible within the scope of the present invention. [Explanation of symbols]

[0025] 1 Cylinder block 2 Oil drain hole 2a Inlet 2b Outlet 3 Cylinder head 4 Bed plate 5 Oil pan 5a Guide 5a1 Inclined surface 6 Crankshaft 6a Crank arm 6b Crank pin 6c Counterweight LE Lower end of rotation path 7 Oil seal retainer 8 Inner wall 8a Mating surface 8b Oil seal retaining portion 9 Outer wall 9a mating surface 9b Bolt hole 10 Space 11 Volt 100 Internal Combustion Engine 101 Wall section

Claims

[Claim 1] a wall portion provided on a side of the internal combustion engine where a transmission case is attached, the wall portion having an oil dropping passage formed therein for causing oil supplied into the cylinder head to flow downward; an oil seal retainer that is provided on the outside of the wall portion, holds an oil seal that is attached around a crankshaft of the internal combustion engine, and is recessed away from the wall portion to form a space between the wall portion and the oil drop passage; an oil pan provided below the wall portion and having a guide portion formed below a lower end of a rotation path of the crankshaft, the guide portion communicating with the space and introducing the oil therein; An internal combustion engine having:

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