Chain case of internal combustion engine

Abstract

To improve sealability between a chain case and an outer peripheral surface of a crank shaft.SOLUTION: A chain case 1 comprises: a resin body part 4 that covers the front surface of an internal combustion engine 20 and has a crankshaft through hole 3 through which a crankshaft 2 of the internal combustion engine 20 passes; a ring member 5 attached around the crankshaft through hole 3; and an oil seal 6 that is attached to the ring member 5, and seals the outer peripheral surface of the crankshaft 2. The body part 4 has a cylindrical boss part 26 into which a dowel pin 27 for positioning with the internal combustion engine 20 is inserted at the outer peripheral edge of the crankshaft through hole 3.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a chain case of an internal combustion engine.

Background Art

[0002] For example, Patent Document 1 discloses a timing belt cover made of a resin material that covers a timing belt disposed on an outer surface of an engine body and has a through hole through which a crankshaft passes.

[0003] The timing belt cover of this Patent Document 1 closes a gap generated between the crankshaft by a disk-shaped seal member attached to the through hole, and blocks belt noise dissipated to the outside through the gap.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in this Patent Document 1, since the timing belt cover is made of a resin material, a displacement occurs between the center position of the seal member and the center position of the crankshaft due to the molding accuracy of the timing belt cover and deformation due to heat, and there is a risk that the sealing performance between the seal member and the outer peripheral surface of the crankshaft deteriorates.

[0006] That is, in a resinous timing belt cover (chain case) as in Patent Document 1, there is room for further improvement in improving the sealing performance with the outer peripheral surface of the crankshaft.

Means for Solving the Problems

[0007] The chain case of the internal combustion engine according to the present invention covers the front or side surface of the internal combustion engine, and includes a resin main body having a crankshaft through-hole through which the crankshaft of the internal combustion engine passes, a ring member attached around the crankshaft through-hole, and an oil seal attached to the ring member and sealing the outer peripheral surface of the crankshaft. The main body is characterized by having a cylindrical boss portion at the outer peripheral edge of the crankshaft through-hole, into which a positioning member for positioning with the internal combustion engine is inserted.

Advantages of the Invention

[0008] According to the present invention, the influence of the displacement of the center of the oil seal with respect to the center of the crankshaft caused by the dimensional change due to the temperature change of the main body is reduced, and the sealing performance of the oil seal with respect to the crankshaft can be easily ensured.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0010] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In each figure, the X-axis represents the front-rear direction (crankshaft axis direction) of the internal combustion engine 20, the Y-axis represents the left-right direction (width direction) of the internal combustion engine 20, and the Z-axis represents the up-down direction (cylinder axis direction) of the internal combustion engine 20.

[0011] FIG. 1 is a front view of the chain case 1 according to the present invention. FIG. 2 is a sectional view of a main part of the internal combustion engine 20 to which the chain case 1 according to the present invention is applied, and is a sectional view of a main part of the internal combustion engine 20 along a plane parallel to the XY plane and including the crankshaft center axis. FIG. 3 is a sectional view of a main part of the internal combustion engine 20 to which the chain case 1 according to the present invention is applied, and is a sectional view of a main part of the internal combustion engine 20 along a plane parallel to the YZ plane. The chain case 1 according to the present invention is attached to, for example, an internal combustion engine 20 mounted on a vehicle.

[0012] The chain case 1 is attached to the internal combustion engine 20 so as to cover the front surface (in other words, the side surface) of the internal combustion engine 20.

[0013] Specifically, the chain case 1 is fixed to a cylinder head (not shown), a cylinder block 21, and an oil pan 22 that constitute the front surface of the internal combustion engine 20. That is, the chain case 1 is disposed across the cylinder head, the cylinder block 21, and the oil pan 22.

[0014] The cylinder head is fixed to the upper deck of the cylinder block 21. The oil pan 22 is fixed to the lower deck 21a of the cylinder block 21 as shown in FIG. 2.

[0015] As shown in FIGS. 1 and 2, the chain case 1 has a main body portion 4 having a crankshaft through hole 3 through which the crankshaft 2 of the internal combustion engine 20 passes, an annular (cylindrical) ring member 5 attached around the crankshaft through hole 3, an annular (cylindrical) oil seal 6 that seals the outer peripheral surface of the crankshaft 2, and an annular spring 7 attached to the outer peripheral surface of the oil seal 6.

[0016] At the front end of the crankshaft 2, as shown in FIG. 2, a crank pulley 8 is attached. A belt for auxiliary machine drive (not shown) is wound around the crank pulley 8. The crank pulley 8 is located outside the chain case 1 and drives auxiliary machines (not shown) such as a water pump via the belt for auxiliary machine drive (not shown). The belt for auxiliary machine drive (not shown) is tensioned by a tensioner (not shown) and a predetermined tension is applied.

[0017] The main body 4 of the chain case 1 is made of a resin material such as synthetic resin like polyamide and is formed by molding.

[0018] The main body 4 has a shallow dish shape and forms a space 23 between it and the front surface of the internal combustion engine 20 as shown in FIG. 2. As shown in FIG. 3, in the space 23, a crank sprocket 24 fixed to the crankshaft 2 and a timing chain 25 which is a rotary power transmission chain wound around the crank sprocket 24 are accommodated. The timing chain 25 is tensioned by a tensioner (not shown) and a predetermined tension is applied. Note that a cam sprocket (not shown) fixed to the front end of a camshaft (not shown) is also accommodated in the space 23 and the timing chain 25 is wound around it.

[0019] As shown in FIG. 2, the periphery of the crankshaft through-hole 3 of the main body 4 is formed in a stepped shape. Further, the main body 4 has an annular protrusion 9 that protrudes along the crankshaft axial direction at the stepped portion around the crankshaft through-hole 3.

[0020] The protrusion 9 is located at the outer peripheral edge of the crankshaft through-hole 3 and protrudes along the crankshaft axial direction. In this embodiment, the protrusion 9 protrudes toward the side not facing the internal combustion engine 20. Note that the protrusion 9 may protrude toward the side facing the internal combustion engine 20.

[0021] As shown in FIG. 2, the ring member 5 has a cylindrical portion 10 having a cylindrical shape, an inner peripheral side protruding portion 11 protruding from the inner peripheral surface of the cylindrical portion 10 toward the inside of the cylindrical portion 10, and an outer peripheral side protruding portion 12 protruding from the outer peripheral surface of the cylindrical portion 10 toward the outside of the cylindrical portion 10.

[0022] The cylindrical portion 10 is sized to accommodate the oil seal 6, and is formed such that the length along the axial direction (the length along the X-axis direction) is longer than the length along the axial direction (the length along the X-axis direction) of the oil seal 6.

[0023] The inner peripheral side protruding portion 11 is an annularly continuous protrusion having a rectangular cross section, and protrudes from the inner peripheral surface of the cylindrical portion 10 toward the inside of the cylindrical portion 10. The outer peripheral surface of the oil seal 6 is vulcanized and adhered to the tip of the inner peripheral side protruding portion 11.

[0024] The outer peripheral side protruding portion 12 is an annularly continuous stepped protrusion, and includes a first protruding wall 13 having a rectangular cross section that protrudes from the outer peripheral surface of the cylindrical portion 10 toward the outside of the cylindrical portion 10, a second protruding wall 14 having a rectangular cross section that extends along the axial direction (X-axis direction) of the cylindrical portion 10 from the tip of the first protruding wall 13, and a third protruding wall 15 having a rectangular cross section that protrudes from the tip of the second protruding wall 14 toward the outside of the cylindrical portion 10. One end of the second protruding wall 14 is connected to the first protruding wall 13, and the other end is connected to the third protruding wall 15.

[0025] The ring member 5 is joined such that the first protruding wall 13, which is the inner peripheral side portion of the outer peripheral side protruding portion 12, is joined to the tip of the protrusion 9 of the main body portion 4. The ring member 5 is joined to the tip of the protrusion 9 of the main body portion 4 by, for example, laser welding. The ring member 5 may be joined to the tip of the protrusion 9 of the main body portion 4 using an adhesive.

[0026] As shown in FIG. 2, the oil seal 6 has a cylindrical shape. The oil seal 6 is made of a rubber material such as fluororubber, and is vulcanized and adhered to the ring member 5 before being joined to the main body portion 4.

[0027] The oil seal 6 is vulcanized and adhered to the tip of the inner peripheral side protrusion 11 of the ring member 5 with its outer peripheral surface being accommodated in the cylindrical portion 10 of the ring member 5. More specifically, the oil seal 6 is vulcanized and adhered to the ring member 5 in a state where it does not protrude outside the cylindrical portion 10 of the ring member 5 along the axial direction (X-axis direction).

[0028] A spring 7 is attached to the outer periphery of one end portion 6a of the oil seal 6. The oil seal 6 suppresses the leakage of oil to the outside from the space 23 formed between the chain case 1 and the front surface of the internal combustion engine 20 by the inner peripheral surface of the one end portion 6a to which the spring 7 is attached being in close contact with the outer peripheral surface of the crankshaft 2 (more precisely, the outer peripheral surface of the portion where the crankshaft 2 of the shaft of the crank pulley 8 is assembled) over the entire circumference.

[0029] In this embodiment, the oil seal 6 is formed such that the inner diameter of the other end portion 6b is smaller than the outer diameter of the crankshaft 2, but it may be formed such that the inner diameter of the other end portion 6b is equal to or larger than the outer diameter of the crankshaft 2 (more precisely, the outer diameter of the portion where the crankshaft 2 of the shaft of the crank pulley 8 is assembled).

[0030] As shown in FIGS. 2 and 3, such a chain case 1 has a cylindrical boss portion 26 formed in the main body portion 4. A metal dowel pin 27 for positioning with the internal combustion engine 20 is inserted into the boss portion 26.

[0031] The chain case 1 is fixed to the internal combustion engine 20 with bolts (not shown) or the like in a state where it is positioned with respect to the internal combustion engine 20 by the dowel pin 27 as a positioning member.

[0032] As shown in FIG. 2, one end side of the dowel pin 27 is inserted into the boss portion 26, and the other end side is press-fitted and fixed into a positioning hole portion 28 formed in the cylinder block 21 of the internal combustion engine 20.

[0033] As shown in FIGS. 1 to 3, the boss portion 26 is formed on the outer peripheral edge of the crankshaft through hole 3. That is, the main body portion 4 has the boss portion 26 on the outer peripheral edge of the crankshaft through hole 3. The boss portion 26 is formed at a position facing the cylinder block 21 located above the oil pan 22.

[0034] As shown in FIG. 3, in the main body portion 4 of the present embodiment, in the view in the crankshaft axial direction, there are a pair of boss portions 26a, 26a that are located sandwiching the crankshaft 2 and are located outside the timing chain 25, and a boss portion 26b that is located inside the timing chain 25 in the view in the crankshaft axial direction.

[0035] These boss portions 26 are formed such that the distances from the center position of the crankshaft through hole 3 are equal to each other. In other words, these plurality of boss portions 26 are formed to be located on the circumference of a circle that is concentric with the crankshaft through hole 3 on the YZ plane. Therefore, for the chain case 1, the dimensional management of the boss portion 26 becomes easy.

[0036] As shown in FIGS. 2 and 3, the boss portion 26 is a cylinder with a substantially uniform wall thickness protruding from the main body portion 4.

[0037] As shown in FIG. 2, the chain case 1 can be positioned by the dowel pin 27 at the outer peripheral edge of the crankshaft through hole 3, which is at a position away from the outer peripheral edge of the chain case, by protruding the boss portion 26 into the space 23 between the internal combustion engine 20.

[0038] Also, the thickness of the main body portion 4 at the position that becomes the bottom of the boss portion 26 is the same as the thickness of the main body portion 4 at the position where the boss portion 26 is not provided.

[0039] Since the main body portion 4 of the chain case 1 is made of a resin material, there may be a displacement between the center position of the oil seal 6 and the center position of the crankshaft 2 due to molding accuracy or deformation due to heat, and the sealing performance between the oil seal 6 and the outer peripheral surface of the crankshaft 2 may deteriorate.

[0040] However, the main body 4 of the chain case 1 in the above-described embodiment has a boss portion 26 for positioning with the internal combustion engine 20 at the outer peripheral edge of the crankshaft through-hole 3.

[0041] By bringing the position of the dowel pin 27 closer to the center position of the oil seal 6, the influence of the displacement of the center position of the oil seal 6 with respect to the center (axis) position of the crankshaft 2 due to the forming accuracy of the main body 4 and the dimensional change due to the temperature change during the operation of the internal combustion engine 20 of the resin main body 4 is reduced, and the sealing performance of the oil seal 6 with respect to the crankshaft 2 can be easily ensured.

[0042] Further, since the boss portion 26 faces the cylinder block 21 and is formed on the internal combustion engine 20 side in the vertical direction, it is difficult for it to be immersed in the oil in the oil pan 22. Therefore, the dowel pin 27 is less likely to come into contact with the oil in the oil pan 22 and is less affected by the oil temperature of the oil in the oil pan 22. That is, the chain case 1 can reduce the dimensional change (amount of elongation) of the dowel pin 27 even when the oil temperature in the oil pan 22 rises, and the accuracy of the center position of the oil seal 6 with respect to the center position of the crankshaft 2 is good (the amount of deviation is small).

[0043] The chain case 1 has a structure in which a cylindrical boss portion 26 protrudes from the main body portion 4, and the thickness of the main body portion 4 at the position that becomes the bottom of the boss portion 26 is the same as the thickness of the main body portion 4 at the position where the boss portion 26 is not provided. If the portion of the boss portion 26 on the main body portion 4 side of the chain case 1 is made solid, the thickness of the main body portion 4 at the position that becomes the bottom of the boss portion 26 and the thickness at the position where the boss portion 26 is not provided will become non-uniform, and there is a risk of sink marks occurring at the position that becomes the bottom of the boss portion 26.

[0044] That is, the chain case 1 has the same thickness of the main body 4 at the position that becomes the bottom of the boss portion 26 as that of the main body 4 at the position where the boss portion 26 is not provided, so that it is possible to suppress the occurrence of sink marks in the main body 4 at the position that becomes the bottom of the boss portion 26 during molding. Further, since it is possible to suppress the occurrence of sink marks in the main body 4 at the position that becomes the bottom of the boss portion 26, it is possible to suppress the deterioration of the molding accuracy of the protrusion 9.

[0045] Furthermore, the chain case 1 has the same thickness of the main body 4 at the position that becomes the bottom of the boss portion 26 as that of the main body 4 at the position where the boss portion 26 is not provided, so that it is possible to suppress the influence of the displacement of the center position of the oil seal 6 with respect to the center (axis) position of the crankshaft 2 caused by the dimensional change of the chain case 1 itself after being assembled to the internal combustion engine 20.

[0046] Also, the chain case 1 is formed in a cylindrical shape over the entire length of the boss portion 26, thereby promoting weight reduction by hollowing.

[0047] As described above, the specific embodiments of the present invention have been described. However, the present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit thereof.

[0048] For example, at least two or more boss portions 26 may be provided on the outer peripheral edge of the crankshaft through hole 3. That is, for example, in the above-described embodiment, the boss portion 26b may be omitted. Also, in the above-described embodiment, for example, four boss portions 26 may be provided.

[0049] The boss portion 26 may be formed to have, for example, a rib having a cross-sectional X shape connected to the inner peripheral surface of the boss portion 26 on the inner periphery of the main body 4 side that does not interfere with the dowel pin 27.

Explanation of reference numerals

[0050] 1... Chain case 2... Crankshaft 3... Crankshaft through hole 4... Main body 5... Ring member 6…Oil seal 7…Spring 8…Crank pulley 20…Internal combustion engine 21…Cylinder block 22…Oil pan 23…Space 24…Crank sprocket 25…Timing chain 26…Boss part 26a…Boss part 26b…Boss part 27…Dowel pin 28…Positioning hole part

Claims

1. A resin main body that covers the front or side surface of an internal combustion engine and has a crankshaft through-hole through which the crankshaft of the internal combustion engine passes, a ring member attached around the crankshaft through-hole, and an oil seal attached to the ring member and sealing the outer peripheral surface of the crankshaft. The main body has a cylindrical boss portion at the outer peripheral edge of the crankshaft through-hole into which a positioning member for positioning with the internal combustion engine is inserted. The chain case of the internal combustion engine is characterized by this.

2. The chain case of the internal combustion engine according to Claim 1, wherein at least two or more boss portions are provided at the outer peripheral edge of the crankshaft through-hole.

3. The boss portions face the cylinder block of the internal combustion engine, are positioned with the crankshaft sandwiched therebetween in a view in the crankshaft axial direction, and are a pair of boss portions positioned outside a chain wound around a crank pulley attached to the crankshaft. The chain case of the internal combustion engine according to Claim 1 or 2 is characterized by this.

4. The boss portion is a cylinder protruding from the main body. The thickness of the main body at the position that becomes the bottom of the boss portion is the same as the thickness of the main body at the position where the boss portion is not formed. The chain case of the internal combustion engine according to any one of Claims 1 to 3 is characterized by this.

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