JP2023072121A - Chain case of internal combustion engine - Google Patents

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

The present invention relates to a chain case for an internal combustion engine.

For example, Patent Literature 1 discloses a timing belt cover made of a resin material that covers a timing belt arranged on the outer surface of an engine body and has a through hole through which a crankshaft passes.

The timing belt cover disclosed in Patent Document 1 closes the gap between the timing belt cover and the crankshaft by means of a disk-shaped seal member attached to the through hole, and blocks belt noise that is radiated to the outside through the gap.

Japanese Utility Model Laid-Open No. 3-54251

However, in Patent Document 1, since the timing belt cover is made of a resin material, misalignment 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. There is a risk that the sealing performance with the outer peripheral surface of the crankshaft will deteriorate.

In other words, the timing belt cover (chain case) made of resin such as that disclosed in Patent Document 1 has room for further improvement in improving the sealing performance with the outer peripheral surface of the crankshaft.

A chain case for an internal combustion engine according to the present invention includes a main body portion made of resin, which covers the front or side surface of the internal combustion engine and has a crankshaft through hole through which the crankshaft of the internal combustion engine passes, and which is attached around the crankshaft through hole. and an oil seal that is attached to the ring member and seals the outer peripheral surface of the crankshaft. It is characterized by having a cylindrical boss into which the positioning member is inserted.

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, which is caused by the dimensional change due to the temperature change of the main body, is reduced, and the sealing performance of the oil seal to the crankshaft can be easily ensured.

1 is a front view of a chain case according to the present invention; FIG. 1 is a cross-sectional view of an internal combustion engine to which a chain case according to the present invention is applied; FIG. 1 is a cross-sectional view of an internal combustion engine to which a chain case according to the present invention is applied; FIG.

An embodiment of the present invention will now be described in detail with reference to the drawings. In each figure, the X-axis is the longitudinal direction of the internal combustion engine 20 (crankshaft axial direction), the Y-axis is the lateral direction (width direction) of the internal combustion engine 20, and the Z-axis is the vertical direction of the internal combustion engine 20 (cylinder axial direction). , respectively.

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

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

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

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

As shown in FIGS. 1 and 2, the chain case 1 includes a body portion 4 having a crankshaft through hole 3 through which a crankshaft 2 of an internal combustion engine 20 passes, and an annular ( a cylindrical) ring member 5 , 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 . .

A crank pulley 8 is attached to the front end of the crankshaft 2 as shown in FIG. An accessory drive belt (not shown) is wound around the crank pulley 8 . The crank pulley 8 is positioned outside the chain case 1 and drives accessories (not shown) such as a water pump via an accessory drive belt (not shown). A tensioner (not shown) adjusts the slackness of the accessory drive belt (not shown) and applies a predetermined tension.

The main body portion 4 of the chain case 1 is made of a synthetic resin material such as polyamide, for example, and molded.

The body portion 4 has a shallow plate shape, and forms a space 23 between itself and the front surface of the internal combustion engine 20, as shown in FIG. As shown in FIG. 3 , the space 23 accommodates a crank sprocket 24 fixed to the crankshaft 2 and a timing chain 25 that is a chain for transmitting rotational power wound around the crank sprocket 24 . The timing chain 25 is adjusted for slack by a tensioner (not shown) and given a predetermined tension. A cam sprocket (not shown) fixed to the front end of a camshaft (not shown) is also accommodated in the space 23, and a timing chain 25 is wound around the cam sprocket.

As shown in FIG. 2 , the main body portion 4 is formed stepwise around the crankshaft through hole 3 . Further, the body portion 4 has an annular protrusion 9 protruding along the axial direction of the crankshaft in a stepped portion around the crankshaft through hole 3 .

The protrusion 9 is positioned 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 .

As shown in FIG. 2, the ring member 5 includes a cylindrical portion 10, an inner peripheral side projecting portion 11 projecting from the inner peripheral surface of the cylindrical portion 10 toward the inside of the cylindrical portion 10, and the cylindrical portion 10 and an outer peripheral side projecting portion 12 that projects outward from the cylindrical portion 10 from the outer peripheral surface of the cylindrical portion 10 .

The cylindrical portion 10 has a size that can accommodate the oil seal 6, and the length along the axial direction (the length along the X-axis direction) is the length along the axial direction of the oil seal 6. (the length along the X-axis direction).

The inner peripheral side projecting portion 11 is an annular continuous projection 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 bonded to the tip of the inner peripheral side projecting portion 11 .

The outer peripheral side protruding portion 12 is a stepped protrusion that continues in an annular shape, 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, and a first protruding wall. 13 and a second projecting wall 14 with a rectangular cross section extending along the axial direction (X-axis direction) of the cylindrical part 10 from the tip of the second projecting wall 13, and a rectangular cross section projecting from the tip of the second projecting wall 14 toward the outside of the cylindrical part 10. and a third protruding wall 15 . The second projecting wall 14 has one end connected to the first projecting wall 13 and the other end connected to the third projecting wall 15 .

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

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

The oil seal 6 is accommodated in the cylindrical portion 10 of the ring member 5 , and its outer peripheral surface is vulcanization-bonded to the tip of the inner peripheral side projecting portion 11 of the ring member 5 . Specifically, the oil seal 6 is vulcanized and bonded to the ring member 5 so as not to protrude outside the cylindrical portion 10 of the ring member 5 along the axial direction (X-axis direction).

A spring 7 is attached to the outer periphery of one end portion 6a of the oil seal 6 . In the oil seal 6, the inner peripheral surface of one end 6a to which the spring 7 is attached is continuous over the entire periphery of the crankshaft 2 (more precisely, the crankshaft 2 and the crankshaft 2 of the crank pulley 8). The oil is prevented from leaking out from the space 23 formed between the chain case 1 and the front surface of the internal combustion engine 20 by being in close contact with the outer peripheral surface of the assembled part.

In this embodiment, the oil seal 6 is formed so that the inner diameter of the other end 6b is smaller than the outer diameter of the crankshaft 2, but the inner diameter of the other end 6b is smaller than the crankshaft 2 (more precisely, The outer diameter of the portion of the shaft of the crank pulley 8 attached to the crankshaft 2) may be larger than the outer diameter.

Such a chain case 1 has a cylindrical boss portion 26 formed on the main body portion 4, as shown in FIGS. A dowel pin 27 made of metal for positioning with the internal combustion engine 20 is inserted into the boss portion 26 .

The chain case 1 is fixed to the internal combustion engine 20 with bolts (not shown) or the like while being positioned with respect to the internal combustion engine 20 by dowel pins 27 as positioning members.

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

The boss portion 26 is formed on the outer peripheral edge of the crankshaft through hole 3, as shown in FIGS. That is, the 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 .

As shown in FIG. 3, the body portion 4 of the present embodiment includes a pair of boss portions 26a, 26a positioned on both sides of the crankshaft 2 and positioned outside the timing chain 25 when viewed in the axial direction of the crankshaft; and a boss portion 26b located inside the timing chain 25 when viewed in the axial direction of the crankshaft.

These boss portions 26 are formed so that the distances from the center position of the crankshaft through hole 3 are equal to each other. In other words, the plurality of boss portions 26 are formed on the circumference of a circle that is concentric with the crankshaft through hole 3 on the YZ plane. Therefore, the chain case 1 facilitates dimensional control of the boss portion 26 .

As shown in FIGS. 2 and 3, the boss portion 26 is a cylinder with a substantially uniform thickness that protrudes from the main body portion 4 .

As shown in FIG. 2, the chain case 1 protrudes the boss portion 26 into the space 23 between itself and the internal combustion engine 20, so that the outer peripheral edge of the crankshaft through hole 3 is positioned away from the outer peripheral edge of the chain case. Positioning by the dowel pin 27 is possible.

Further, the thickness of the body portion 4 at the bottom portion of the boss portion 26 is the same as the thickness of the body portion 4 at the position where the boss portion 26 is not provided.

Since the main body 4 of the chain case 1 is made of a resin material, misalignment occurs between the center position of the oil seal 6 and the center position of the crankshaft 2 due to deformation due to molding accuracy or heat. There is a possibility that the sealing performance between the outer peripheral surface of 2 will deteriorate.

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

By bringing the position of the dowel pin 27 and the center position of the oil seal 6 close to each other, the chain case 1 is designed so that the molding accuracy of the main body 4 and the dimensional change of the resin main body 4 due to temperature changes during operation of the internal combustion engine 20 affect the crankshaft. The influence of positional deviation of the center position of the oil seal 6 with respect to the center (axial) position of the crankshaft 2 is reduced, and the sealing performance of the oil seal 6 with respect to the crankshaft 2 can be easily ensured.

Further, since the boss portion 26 faces the cylinder block 21 and is formed on the side of the internal combustion engine 20 in the vertical direction, the boss portion 26 is less likely to be submerged 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 likely to be affected by the oil temperature of the oil in the oil pan 22 . In other words, the chain case 1 can reduce the dimensional change (elongation amount) of the dowel pin 27 even when the temperature of the oil in the oil pan 22 increases, and the accuracy of the center position of the oil seal 6 with respect to the center position of the crankshaft 2 is improved. Good (the amount of deviation is small).

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 bottom portion of the boss portion 26 is equal to the thickness of the position where the boss portion 26 is not provided. is the same as the thickness of the main body portion 4 of . In the chain case 1, if the portion of the boss portion 26 on the side of the body portion 4 is made solid, the thickness of the body portion 4 at the bottom portion of the boss portion 26 and the thickness at the portion where the boss portion 26 is not provided are uneven. As a result, there is a risk that sink marks will occur at the position that will be the bottom of the boss portion 26 .

In other words, in the chain case 1, the thickness of the body portion 4 at the bottom portion of the boss portion 26 is the same as the thickness of the body portion 4 at the position where the boss portion 26 is not provided, so that the boss portion 1 is formed at the time of molding. It is possible to suppress the occurrence of sink marks in the main body portion 4 at the position that serves as the bottom portion of the portion 26 . In addition, since it is possible to suppress the occurrence of sink marks in the main body portion 4 at the position that serves as the bottom portion of the boss portion 26, it is possible to suppress the deterioration of the molding accuracy of the protrusions 9.

Further, in the chain case 1, the thickness of the body portion 4 at the bottom portion of the boss portion 26 is the same as the thickness of the body portion 4 at the position where the boss portion 26 is not provided. 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 center) position of the crankshaft 2, which is caused by the dimensional change of the oil seal 6 itself after being assembled.

In addition, the chain case 1 has the boss portion 26 formed in a cylindrical shape over the entire length, thereby reducing the weight of the chain case 1 by removing lightening.

Although specific embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention.

For example, at least two boss portions 26 may be provided on the outer peripheral edge of the crankshaft through hole 3 . That is, for example, the boss portion 26b may be omitted in the above-described embodiments. Further, in the above-described embodiment, for example, four boss portions 26 may be set.

The boss portion 26 may be formed so as to have, for example, an X-shaped cross-sectional rib connected to the inner peripheral surface of the boss portion 26 on the inner periphery of the body portion 4 side that does not interfere with the dowel pin 27 .

Reference Signs List 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 portion 26 a Boss portion 26 b Boss portion 27 Dowel pin 28 Positioning hole

Claims (4)

A resin main body covering the front or side surface of an internal combustion engine and having a crankshaft through hole through which a crankshaft of the internal combustion engine passes; a ring member attached around the crankshaft through hole; and attached to the ring member. and an oil seal that seals the outer peripheral surface of the crankshaft,
A chain case for an internal combustion engine, wherein the body portion has a cylindrical boss portion into which a positioning member for positioning with respect to the internal combustion engine is inserted, on the outer peripheral edge of the crankshaft through hole. 2. The chain case for an internal combustion engine according to claim 1, wherein at least two boss portions are provided on the outer peripheral edge of said crankshaft through hole. The boss portion faces a cylinder block of the internal combustion engine, is positioned across the crankshaft when viewed in the axial direction of the crankshaft, and is positioned outside a chain wound around a crank pulley attached to the crankshaft. 3. A chain case for an internal combustion engine according to claim 1 or 2, wherein said chain case is a pair of boss portions that align with each other. The boss portion is a cylinder protruding from the main body portion,
4. The body according to any one of claims 1 to 3, wherein a thickness of the main body at a position that serves as a bottom of the boss is the same as a thickness of the main body at a position where the boss is not formed. A chain case for an internal combustion engine as described above.

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