FIELD OF THE INVENTION

This invention relates to an oil seal apparatus for preventing entry of muddy water and the like. More particularly, it relates to an oil seal apparatus suited for use in the front portion of an internal combustion engine.

BACKGROUND OF THE INVENTION

In oil seal apparatuses used for casings containing equipment, lips are provided to prevent the entry of dust, rainwater and muddy water which might otherwise contact the equipment.

Especially in the front portion of the cylinder block of an internal combustion engine, the crankshaft projects and the crankshaft pulley is fixed to the projection. Therefore, an oil seal fitted between the cylinder block and the crankshaft is more liable to be exposed to dust, rainwater and muddy water. The conventional oil seal comprises a main lip for oil sealing and a dust lip to prevent the entry of dust etc. However, this known seal has not been able to prevent the entry of rainwater or muddy water which runs down along the cylinder block or crankshaft pulley.

Accordingly, an object of this invention is to provide an oil seal apparatus effective for preventing the muddy water etc. which runs down along the equipment casing from entering into the oil sealed portion of the casing.

Another object of this invention is to provide an oil seal apparatus effective for preventing the muddy water etc. which runs down along a rotating member, such as the crankshaft pulley fixed to the shaft outside the casing, from entering into the casing.

A further object of this invention is to provide an oil seal apparatus especially suited for use in the front portion of the cylinder block of an internal combustion engine.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view of an internal combustion engine to which this invention is applied.

FIG. 2 is a cross-sectional view showing a conventional oil seal apparatus.

FIG. 3 is a cross-sectional view of an oil seal apparatus embodying this invention.

FIG. 4 is a cross-sectional view of another oil seal apparatus embodying this invention.

FIG. 5 is a cross-sectional view of still another oil seal apparatus embodying this invention.

DETAILED DESCRIPTION

In FIG. 1, a crankshaft 4 rotates in a crankcase 3 defined by the cylinder block 1 and oil pan 2 of an internal combustion engine. The crankshaft 4 is rotatably supported by end walls 5 and 6 of the cylinder block and intermediate bearing caps 7.

An oil seal 8 is fitted to the front end wall 5 of the cylinder block 1 to prevent the leakage of oil from the crankcase 3. The oil seal 8 is usually provided in an oil seal housing 9 which is mounted on the front end of the crankcase. The projecting front end of the crankshaft 4 is fitted with a pulley 10 to drive a fan, water pump or generator (not shown) by means of a belt, as is conventional.

Referring to FIG. 2, a conventional oil seal apparatus will now be described.

At the projecting front end of a crankshaft 12, which passes through an oil seal housing 11, there is fixed a crankshaft pulley 13 by means of a bolt 14. The pulley 13 consists of a tubular shaft portion 16 into which an end 15 of the crankshaft 12 is inserted and a boss portion 17 and a disc portion 18, both rising radially from said shaft portion 16. An oil seal 19 coacts between the housing 11 and the pulley 13, and includes a cup-shaped mounting portion 21 which is fixed to the housing 11 and confines a core plate 20, a main lip portion 23 which is kept snugly in contact with the shaft portion 16 by a spring 22, and a dust lip portion 24 which is positioned closer to the crankshaft pulley 13 than said main lip portion 23 and is kept in snug contact with the shaft portion 16. Here, the dust lip portion 24 is formed as an annular sheet or rib which extends primarily radially with respect to the shaft portion 16. The rib portion 24 has the inner annular edge thereof disposed in snug sliding contact with the rotatable shaft to create a seal therewith.

As illustrated in FIG. 2, the oil seal 19, which includes the mounting portion 21 and the lip portions 23 and 24, is formed integrally as a one-piece member and is preferably constructed from an elastomeric material, such as rubber. This one-piece seal 19 is suitably reinforced, however, by the core plate 20 which is also cup-shaped and disposed within the cup-shaped mounting portion 21.

The above-described conventional oil seal apparatus has the following shortcoming. When the entire unit is splashed with muddy water, the water flows along the housing 11 and mounting portion 21 onto the dust lip portion 24, as indicated by the arrow P. The water also flows through the crankshaft pulley 13 onto the dust lip portion 24, as indicated by the arrow Q. Therefore, the conventional oil seal apparatus involves the risk of muddy water flowing into the equipment past the dust lip portion 24. This entry of muddy water increases impurities in the crankcase oil and accelerates abrasion in various parts of the equipment. In addition, it gives rise to abnormal wear in the main lip portion 23 of the oil seal and the shaft portion 16 with which said main lip portion 23 is kept in snug contact.

To prevent the entry of muddy water, the dust lip portion 24 has been strongly pressed against the shaft portion 16. This method, however, generates much heat at the contact area, whereby the oil seal made of rubber becomes less durable through deterioration. Also, it may accelerate the wear of the shaft by the dust lip itself.

This invention has overcome such shortcoming of the conventional oil seal apparatus. An oil seal apparatus embodying this invention will now be described with reference to FIG. 3.

Because the oil seal apparatus according to this invention differs from the conventional one (as shown in FIG. 2) only in the construction of the dust lip portion, a description of the other details has been omitted.

As shown in FIG. 3, the dust lip portion according to this invention is provided with an axially extending auxiliary lip or flange 25, which lip 25 is provided at a position closer to the crankshaft pulley 13, as compared with the main lip portion 23. The auxiliary lip 25, which is integral with and projects axially from the radially innermost portion of the dust lip portion 24, projects axially outwardly beyond the outer end face 30 of the oil seal and is formed with an annular water-collecting groove 26 along its periphery. This groove 26, which thus surrounds the lip 25, is preferably formed with its inner annular surface 26' disposed so that it sloped radially inwardly toward the crankshaft as the groove projects axially inwardly from the free end of the lip. Because of this, that portion of the groove 26 which is disposed above the crankshaft thus has the inner end thereof disposed below the mouth of the groove, whereby the water flowing downwardly along the front face of the crankcase will accordingly readily flow into the groove. The outer annular surface 26" of the groove is also preferably sloped similar to the surface 26'.

In the oil seal apparatus according to FIG. 3, descending muddy water is caught by the groove 26 as indicated by arrow R. The water then flows along the groove 26 down to below the shaft portion 16, and is discharged as indicated by the arrow R'. This eliminates the risk of entry of water into the engine crankcase, such as is experienced with the conventional oil seal apparatus of FIG. 2.

Another embodiment of the invention, as shown in FIG. 4, is designed so as to catch the muddy water which descends along the crankshaft pulley 13. The structure of this embodiment is identical to FIG. 3 except that the auxiliary lip 25 has an axial end flange 27 which flares radially outwardly and is placed either in contact with, or with a little space (h) from, the end face 28 of the boss portion 17. It is desirable that the space (h) is as little as possible.

In the above-described oil seal apparatus according to FIG. 4, muddy water descending along the housing 11 is caught by the groove 26, as indicated by the arrow S. The water flowing down along the crankshaft pulley 13 is also caught by the groove 26, as indicated by the arrow T.

In this embodiment, muddy water can not enter past the main lip portion 23 because the end 27 of the auxiliary lip 25 is positioned in contact with, or with the small space (h) from, the face 28 of the boss portion 17.

Next, a further embodiment as shown in FIG. 5 will be described. This embodiment is designed so as to positively guide muddy water descending along the crankshaft pulley 13 into the groove 26. To attain this end, an annular riblike projection 29 is formed on the boss portion 17 of the pulley 13. The projection 29 extends axially from the end face 28 of the boss portion 17, and enclosingly surrounds the end 27 of the auxiliary lip 25. It is desirable that the radial clearance space (h') between the outside of the end 27 of the auxiliary lip 25 and the inside of the projection 29 be as small as possible. They may be in contact, if necessary.

In the above-described embodiment, muddy water descending along the crankshaft pulley 13 is positively guided to the groove 26 along the periphery of the annular projection 29, as indicated by arrow U, thus preventing the entry of muddy water into the main lip portion 23.

The above description is made with respect to an oil seal apparatus for use in the front portion of an internal combustion engine. However, this invention is not limited to the above-described embodiments, since it is applicable to all equipment which are subject to be splashed with muddy water and the like.

The construction of the rotating member, such as the crankshaft pulley, is not limited to the above embodiments. Various design modifications are possible without departing from the technical scope of this invention.

As will be understood from the above, this invention prevents the entry of muddy water through the oil seal, thereby preventing an increase in impurities in the oil and increasing the durability of the oil seal itself.

Although a particular preferred embodiment of the invention has been disclosed in detail for illustrative purposes, it will be recognized that variations or modifications of the disclosed apparatus, including the rearrangement of parts, lie within the scope of the present invention.