Sealing device for water pump bearings

A sealing device for a water pump bearing employs a seal member without an axial lip, and having only a radial lip. The sealing device includes an annular seal member which is fixed to a shoulder portion of one end in an axial direction of an outer race of a water pump bearing and an annular slinger which is positioned on a side of the one end in the axial direction with respect to the seal member and externally fixed to the outer peripheral face of a pump shaft serving as an inner race. The seal member has a section shape which is bent along a disk portion and an outer cylindrical portion of the slinger. A labyrinth seal portion is formed between the seal member, and the disk portion and the outer cylindrical portion of the slinger. Radial lips are formed on an inner periphery of the seal member.

BACKGROUND OF THE INVENTION

The present invention relates to a sealing device for a water pump bearing.

For example, a structure such as shown inFIG. 8is known as a water pump for circulating cooling water in an automobile engine, or the like.

The water pump comprises a pump shaft1, an impeller2, a mechanical seal3, a water pump bearing4, sealing devices5and6for the water pump bearing, a pulley7, etc. The impeller2is attached to one end of the pump shaft1, and the pulley7is attached to the other end. The pump shaft1and the impeller2are rotated by a belt (a belt which transmits rotation of a crankshaft of an engine) which is wound around the pulley7, so that cooling water in a pump chamber is sent out.

In the water pump bearing4, the pump shaft1is used as an inner race, and an outer race41is externally attached to the outer peripheral face of the inner race via a cylindrical roller group42and a ball group43serving as rolling elements. The bearing4is disposed in a boss portion10of a pump housing.

The sealing device5which is disposed on the side of one end (on the side of the impeller) in the axial direction of the water pump bearing4performs a sealing action so that, even when the cooling water in the pump chamber leaks from the mechanical seal3, the cooling water does not enter the interior of the water pump bearing4, thereby allowing the leaking cooling water to be discharged to the outside through a drain hole111of the boss portion10. The sealing device5is configured by an annular seal member51and an annular slinger52.

The seal member51of the sealing device5is fixed to a shoulder portion of one end in the axial direction of the outer race41, and, as enlargedly shown inFIG. 9, configured by integrally heat bonding an elastic member51bin which two radial lips51cand51d, and one axial lip51eare formed, and which is made of synthetic rubber or the like, to an annular core51a. By contrast, the slinger52is positioned on the side of the one end (on the side of the impeller) in the axial direction with respect to the seal member51, and externally fitted and fixed to the outer peripheral face of the pump shaft1. The axial lip51eof the seal member51is in contact with a disk portion52aof the slinger52. The two radial lips51cand51dof the seal member51are in contact with the outer peripheral face of the pump shaft1.

In the sealing device5of the water pump bearing4which is on the side of the impeller, the seal performance is improved by using the seal member51of the triple lip type in which the two radial lips51cand51dand the one axial lip51eare disposed. However, the seal member51of the triple lip type configured as described above has a complicated structure because it has the axial lip51e, thereby producing a problem in that the cost is increased.

The invention has been conducted in order to solve the aforementioned problem. It is an object of the invention to provide a sealing device for a water pump bearing which can exhibit excellent seal performance although using an economical seal member of a simple structure having no axial lip.

SUMMARY OF THE INVENTION

In order to attain the object, a sealing device on a side of an impeller of a water pump bearing is configured by using a pump shaft as an inner race, the impeller being attached to one end of the pump shaft, a pulley being attached to another end, and by externally attaching an outer race via rolling elements to an outer peripheral face of the pump shaft, wherein

the sealing device comprises: an annular seal member which is fixed to a shoulder portion of one end in an axial direction of the outer race; and an annular slinger having an inner cylindrical portion and a disk portion which is extended in a radial direction, the inner cylindrical portion being positioned on a side of the one end in the axial direction with respect to the seal member and externally fitted and fixed to the outer peripheral face of the pump shaft,

the seal member has a section shape which is bent along the disk portion of the slinger, and an outer cylindrical portion which is extended from an outer periphery of the disk portion toward the other end in the axial direction, a labyrinth seal portion is formed between the seal member, and the disk portion and the outer cylindrical portion of the slinger, and a radial lip is disposed on an inner periphery of the seal member.

In the sealing device for a water pump bearing, the economical seal member which is not provided with an axial lip and, which has only a radial lip is fixed to the shoulder portion of the outer race. However, the seal member has a section shape which is bent along the disk portion and the outer cylindrical portion of the slinger, and the labyrinth seal portion is formed between the seal member, and the disk portion and the outer cylindrical portion of the slinger. Although an axial lip is not disposed, therefore, the labyrinth seal portion and the radial lip alone can exhibit sufficient seal performance.

According to another feature of the sealing device of the invention, the radial lip of the seal member may be in contact with the outer peripheral face of the pump shaft, or placed in close proximity to the outer peripheral face of the pump shaft so as to form the labyrinth seal portion. Alternatively, the radial lip may be in contact with an outer peripheral face of the inner cylindrical portion of the slinger, or placed in close proximity to the outer peripheral face of the inner cylindrical portion of the slinger so as to form the labyrinth seal portion. In both the cases, excellent seal performance is exhibited by the radial lip and the formed labyrinth seal portion.

Another embodiment of the invention provides a sealing device on a side of an impeller of a water pump bearing configured by using a pump shaft as an inner race, the impeller being attached to one end of the pump shaft, a pulley being attached to another end, and by externally attaching an outer race via rolling elements to an outer peripheral face of the pump shaft, wherein

the sealing device comprises: an annular seal member which is fixed to a shoulder portion of one end in an axial direction of the outer race; and an annular slinger having an inner cylindrical portion and a disk portion which is extended in a radial direction, the inner cylindrical portion being positioned on a side of the one end in the axial direction with respect to the seal member and externally fitted and fixed to the outer peripheral face of the pump shaft,

the seal member has a section shape which is bent along the disk portion of the slinger, and an outer cylindrical portion which is extended from an outer periphery of the disk portion toward the other end in the axial direction, an expanded portion of an elastic member is formed in an axial direction of the bent portion, a labyrinth seal portion is formed between the expanded portion, and the disk portion and the outer cylindrical portion of the slinger, and a radial lip is disposed on an inner periphery of the seal member.

In the sealing device for a water pump bearing, the expanded portion disposed in the bent portion of the seal member can increase the distance in the axial direction of the labyrinth seal portion formed between the outer cylindrical portion and the expanded portion, and a process of bending a core constituting the seal member can be easily conducted. In accordance with another feature, the radial lip of the seal member may be in contact with the outer peripheral face of the pump shaft, or placed in close proximity to the outer peripheral face of the pump shaft so as to form the labyrinth seal portion. Alternatively, the radial lip may be in contact with an outer peripheral face of the inner cylindrical portion of the slinger, or placed in close proximity to the outer peripheral face of the inner cylindrical portion of the slinger so as to form the labyrinth seal portion. In both the cases, excellent seal performance is exhibited by the radial lip and the formed labyrinth seal portion.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1is a partial section view showing the structure of a water pump into which a sealing device for a water pump bearing of a first embodiment of the invention is incorporated, andFIG. 2is an enlarged section view of the upper half of the sealing device.

The water pump has the same structure as the above-described conventional water pump, with the exception of a sealing device8of a water pump bearing4on the side of the impeller2, and comprises a pump shaft1, an impeller2, a mechanical seal3, the water pump bearing4, sealing devices6and8for the water pump bearing, a pulley7, etc.

The pump shaft1has a small-diameter portion and a large-diameter portion. The mechanical seal3is disposed on the small-diameter portion, and the water pump bearing4is disposed on the large-diameter portion. The impeller2is attached to one end of the pump shaft1, and the pulley7is attached to the other end. The pump shaft1and the impeller2are rotated by a belt (a belt which transmits rotation of a crankshaft of an engine) which is wound around the pulley7, so that cooling water in a pump chamber is sent out.

The mechanical seal3is configured by: an outer annular member31which is internally fitted and fixed to a boss portion10of a pump housing; an inner annular member32which is externally fitted and fixed to the small-diameter portion of the pump shaft1; a rubber sleeve33which is externally attached to an inner peripheral cylindrical portion31aof the outer annular member31; a rotary ring34which is disposed on a portion of the inner annular member32on the side of the impeller2; a fixing ring35which is externally fitted to the inner peripheral cylindrical portion31aof the outer annular member31so as to be slidable toward the impeller2; and a coil spring36which is disposed in a compressed state on the outer periphery of the rubber sleeve33, and which presses the fixing ring35against the rotary ring34.

The water pump bearing4is a so-called integral shaft bearing, and uses the pump shaft1as an inner race. An outer race41is externally attached to the outer peripheral face of the large-diameter portion of the pump shaft1via a cylindrical roller group42and a ball group43which serve as rolling elements, and which are arranged in two rows in the axial direction. The outer race41is internally fitted and fixed to the boss portion10of the pump housing, and the sealing devices6and8are attached between the shoulder portions of the both ends in the axial direction of the inner peripheral face of the outer race41, and the outer peripheral face of the large-diameter portion of the pump shaft1.

The sealing device6on the side of the pulley7prevents entering of foreign materials and water from the outside, and is configured by a seal member which is fixed to a shoulder portion on the side of the other end (on the side of the pulley) in the axial direction of the outer race41. By contrast, the sealing device8on the side of the impeller and according to the invention is used for, even when the cooling water leaks from the mechanical seal3, blocking the cooling water from entering the water pump bearing4, thereby allowing the cooling water to be discharged through a drain hole11of the boss portion10. The sealing device8is configured by a seal member81and a slinger82.

In the slinger82of the sealing device8, as shown inFIG. 2, an inner cylindrical portion82bis extended from an inner periphery of a disk portion82atoward the one end (toward the impeller2) in the axial direction, and an outer cylindrical portion82cis extended from an outer periphery of the disk portion82atoward the other end (toward the water pump bearing4) in the axial direction, so that the slinger has a step-like section shape. The slinger is produced by conducting a pressing process on a rolled steel plate or the like. The slinger82is positioned on the side of the one end (on the side of the impeller) in the axial direction with respect to the seal member81, and externally fitted and fixed to the outer peripheral face of the pump shaft1. The tip end of the outer cylindrical portion82cis in close proximity to an end of the outer race41.

On the other hand, the seal member81is configured by integrally heat bonding an annular elastic member81bin which two radial lips81cand81dare formed on the inner periphery, and which is made of synthetic rubber or the like, to an annular core81a. An outer peripheral edge of the seal member is attached by means of engaging fixation to a shoulder portion41ain one end of the axial direction of the outer race41. The seal member81has a section shape in which an intermediate portion is bent into a substantially U-like shape so as to extend along the disk portion82aand the outer cylindrical portion82cof the slinger82, whereby a labyrinth83of a sufficient length is formed between the seal member81, and the disk portion82aand the outer cylindrical portion82cof the slinger82. The two radial lips81cand81dof the seal member81are in contact with the outer peripheral face of the pump shaft1.

In the thus configured sealing device8, since the economical seal member81of the double lip type having no axial lip is used, the cost can be reduced. Since the labyrinth seal portion83of a sufficient length is formed between the seal member81, and the disk portion82aand the outer cylindrical portion82cof the slinger82, moreover, sufficient seal performance can be ensured by the labyrinth seal portion83and the two radial lips81cand81deven when an axial lip is not disposed.

In the embodiment described above, the two radial lips81cand81dof the seal member81are brought into contact with the outer peripheral face of the pump shaft1. Alternatively, as shown for example inFIG. 2b, the radial lips81cand81dmay be placed in close proximity to the outer peripheral face of the pump shaft1so that a labyrinth seal portion is formed between the radial lips81cand81dand the outer peripheral face of the pump shaft1. In this case also, excellent seal performance is exhibited by the labyrinth seal portion formed between the radial lips81cand81dand the outer peripheral face of the pump shaft1, and the above-mentioned labyrinth seal portion83.

FIG. 3is an enlarged section view of the upper half of a sealing device for a water pump bearing of a second embodiment of the invention.

In the slinger82of the sealing device8, the inner cylindrical portion82band the outer cylindrical portion82care extended from the inner and outer peripheries of the disk portion82atoward the other end (toward the water pump bearing4) in the axial direction, respectively, so that the slinger has a substantially U-like section shape. The slinger is configured so that the two radial lips81cand81don the inner periphery of the seal member81are in contact with the outer peripheral face of the inner cylindrical portion82b.

The other configuration of the sealing device8is identical with that of the above-described sealing device. Therefore, the identical components are denoted by the same reference numerals inFIG. 3, and their description is omitted.

In the thus configured sealing device8also, since the economical seal member81of the double lip type having no axial lip is used, the cost can be reduced. Even when an axial lip is not disposed, sufficient seal performance can be ensured by the labyrinth seal portion83which is formed between the seal member81, and the disk portion82aand the outer cylindrical portion82cof the slinger82, and which has a sufficient length, and the two radial lips81cand81d.

In the sealing device also, as shown for example inFIG. 3a, the radial lips81cand81dmay be placed in close proximity to the outer peripheral face of the inner cylindrical portion82bso that a labyrinth seal portion is formed between the radial lips81cand81dand the outer peripheral face of the inner cylindrical portion82bof the slinger, thereby allowing excellent seal performance to be exhibited by the labyrinth seal portion and the above-mentioned labyrinth83.

Next,FIG. 4is an enlarged view of the labyrinth seal portion which is formed by the seal member81and the slinger82inFIGS. 2 and 3. As described above, the labyrinth seal portion83is formed between the seal member81, and the disk portion82aand the outer cylindrical portion82cof the slinger82. In this case, the gap a in the axial direction of the labyrinth seal portion between the elastic member81bin the axial-direction portion of a substantially U-like shape which is formed in the intermediate portion of the seal member81, and the disk portion82ais set to 0.05 to 0.8 mm, preferably, 0.2 mm to 0.8 mm, and the length b in a radial direction of the labyrinth seal portion is set to about 1 mm. Similarly, the length c in the axial direction of the labyrinth seal portion between the elastic member81bin the lateral-direction portion of a substantially U-like shape which is formed in the intermediate portion of the seal member81, and the outer cylindrical portion82cis set to 1 mm or longer, and the gap d in a radial direction of the labyrinth seal portion is set to 0.05 to 1.0 mm, preferably, about 0.2 mm to 1.0 mm. In the portion of the core81aon the side of the outer periphery of a substantially U-like shape of the seal member81, a draft angle of about 3′ is formed in the direction from the slinger82to the bearing4.

Next,FIG. 5is an enlarged section view of the upper half of a sealing device for a water pump bearing of a third embodiment of the invention. The embodiment is similar to the first embodiment. In the seal member81, namely, an intermediate portion is formed so as to have a section shape which is bent into a substantially U-like shape, whereby the labyrinth83of a sufficient length is formed between the seal member81, and the disk portion82aand the outer cylindrical portion82cof the slinger82. In this case, an expanded portion81b, in the axial direction in the elastic member81bof the substantially U-like shape which is integrally heat bonded to the annular core81aconstituting the seal member81is formed to be thick. In order to increase the distance d (seeFIG. 4) of the labyrinth seal portion in a radial direction between the elastic member81bof the seal member81and the outer cylindrical portion82c, the annular core81amust be extremely bent. Therefore, this is difficult. Consequently, this is substituted with the formation of the axially-thick expanded portion81b, which is the substantially U-like bent portion of the elastic member81bthat is integrally heat bonded to81a. As a result, a process of bending the core81acan be easily conducted, and the distance d of the labyrinth seal portion in a radial direction between the elastic member81band the outer cylindrical portion82ccan be easily increased.

FIG. 6is an enlarged section view of the upper half of a sealing device for a water pump bearing of a fourth embodiment of the invention. The embodiment is similar to the second embodiment. In the slinger82of the sealing device8, namely, the inner cylindrical portion82band the outer cylindrical portion82care extended from the inner and outer peripheries of the disk portion82atoward the other end (toward the water pump bearing4) in the axial direction, respectively, so that the slinger has a substantially U-like section shape. The slinger is configured so that the two radial lips81cand81don the inner periphery of the seal member81are in contact with the outer peripheral face of the inner cylindrical portion82b. In this case also, the axially-thick expanded portion81b, of the bent portion of the substantially U-like shape in the elastic member81bwhich is integrally heat bonded to the annular core81aconstituting the seal member81is formed. This case also is identical as the above-described third embodiment, and hence description is omitted.

Next,FIG. 7is an enlarged view of a labyrinth seal portion which is formed by the seal member81and the slinger82inFIGS. 5 and 6. In this case also, the labyrinth seal portion83is formed between the seal member81, and the disk portion82aand the outer cylindrical portion82cof the slinger82. The gap a in the axial direction of the labyrinth seal portion between the elastic member81bhaving the expanded portion81b, in the axial-direction portion of a substantially U-like shape which is formed by bending in the intermediate portion of the seal member81, and the disk portion82ais set to 0.05 mm to 0.8 mm, preferably, 0.2 mm to 0.8 mm, and the length b in a radial direction of the labyrinth seal portion is set to about 1 mm. The length c in the axial direction of the labyrinth seal portion between the elastic member81bin the lateral-direction portion which has the expanded portion81b, of a substantially U-like shape, and the outer cylindrical portion82cis set to 0.5 mm or longer, preferably, 1 mm or longer, and the gap d in a radial direction of the labyrinth seal portion is set to 0.05 to 1.0 mm, preferably, about 0.2 mm to 1.0 mm. In the portion of the core81aon the side of the outer periphery of a substantially U-like shape of the seal member81, a draft angle of about 30 is formed in the direction from the slinger82to the bearing4.

In the above-described third and fourth embodiments also, the two radial lips81cand81dof the seal member81may be placed in close proximity to the outer peripheral face of the pump shaft1or that of the inner cylindrical portion82bso that a labyrinth seal portion is formed between the radial lips and the outer peripheral face. In this case also, excellent seal performance can be exhibited by the labyrinth seal portion formed and the above-mentioned labyrinth seal portion83.

As is apparent from the above description, the sealing device for a water pump bearing of the invention provides advantage in that a seal member having no axial lip is used and hence the cost can be reduced, and that, even when an axial lip is not disposed, sufficient seal performance can be ensured by a labyrinth seal portion formed between the seal member, and an annular plate portion and an outer cylindrical portion of a slinger, and a radial lip on the inner periphery of the seal member.