Water pump   

Abstract: A water pump is constructed to have a rotating member that is adapted to be rotated by an external driving source, a housing that forms a part of a pump chamber from which a cooling water is led to an internal combustion chamber for cooling the engine upon rotation of the rotating member, a mechanical seal unit that is installed between the housing and the rotating member to seal the pump chamber and a bearing that is operatively disposed between the rotating member and the housing at a position other than the pump chamber, in which an annular slinger is arranged at an axial end of the bearing and fixed to a fixed portion, the annular slinger having a given portion that slidably contacts to the rotating member.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates in general to water pumps for pumping a cooling water that circulates in an engine cooling system of a motor vehicle, and more particularly to the water pumps of a type that provides a bearing of a rotating member with a watertight construction.

2. Description of the related Art

Japanese Laid-open Patent Application (Tokkai) 2010-169143 shows a water pump that has a watertight construction for a bearing of a rotating member.

In the water pump shown in the publication, there is disclosed a watertight construction between a cylindrical pump housing and a drive shaft that is concentrically and rotatably disposed in the pump housing. Between the pump housing and the drive shaft, there is disposed a ball bearing of a type that has two rows of balls for smoothing rotation of the drive shaft.

The watertight construction comprises a seal member that is fixed to the pump housing and has first and second lip portions slidably contacting with a flat portion formed on the drive shaft, and an annular slinger that is fixed to the drive shaft and has a peripheral portion to which a third lip (or axial lip) of the seal member slidably contacts. Due to the first and second lips that slidably contact to the flat portion of the drive shaft, there are defined two sealing portions by which water penetration into the ball bearing is restrained.

SUMMARY

Although the watertight construction disclosed by the above-mentioned publication exhibits a watertight function to a certain extent due to provision of the two sealing portions, the sliding contact between the third lip and the annular slinger causes formation of an annular space in which water is collected, which however promotes the undesired penetration of water into the ball bearing from the annular space through the two sealing portions.

It is therefore an object of the present invention to provide a water pump which is free of the above-mentioned drawback.

According to the present invention, there is provided an improved watertight construction for a ball bearing installed in a water pump, that exhibits a satisfied watertight function by providing means by which water staying in the annular space is easily discharged therefrom.

In accordance with a first aspect of the present invention, there is provided a water pump which comprises a rotating unit including a pulley, a drive shaft and an impeller which rotate as a single unit; a housing covering the drive shaft and having a pump chamber for receiving therein the impeller; a mechanical seal unit installed between the housing and the drive shaft to seal the pump chamber; a bearing including an outer race fixed to one of the rotating unit and the housing, an inner race fixed to the other one of the rotating unit and the housing and a plurality of rotating bodies operatively disposed between the outer and inner races; an annular seal member arranged at an axial end of the bearing and having a peripheral portion that is fixed to one of the outer and inner races and another peripheral portion that slidably contacts with the other one of the outer and inner races; and an annular slinger fixed to the housing in a manner to face the annular seal member, the annular slinger having a given portion that slidably contacts with a given portion of the rotating unit.

In accordance with a second aspect of the present invention, there is provided a water pump which comprises a rotating unit including a pulley, a drive shaft and an impeller which rotate as a single unit; a housing covering the drive shaft and having a pump chamber for receiving therein the impeller; a mechanical seal unit installed between the housing and the drive shaft to seal the pump chamber; a bearing including an outer race fixed to one of the rotating unit and the housing, an inner race fixed to the other one of the rotating unit and the housing and a plurality of rotating bodies operatively disposed between the outer and inner races; and an annular slinger arranged in a passage extending between the bearing and the mechanical seal unit, the annular slinger being fixed to the housing and having a given portion that slidably contacts to a rotating member fixed to the rotating unit, the rotating member being either one of the outer and inner races of the bearing.

In accordance with third aspect of the present invention, there is provided a water pump which comprises a rotating member adapted to be rotated by an external driving source; a housing that forms at least a part of a pump chamber from which a cooling water is led to an internal combustion chamber for cooling the engine upon rotation of the rotating member; a mechanical seal unit installed between the housing and the rotating member to seal the pump chamber; a bearing operatively disposed between the rotating member and the housing at a position other than the pump chamber; and an annular slinger arranged at an axial end of the bearing and fixed to a fixed portion, the annular slinger having a given portion that slidably contacts to the rotating member.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and advantages of the present invention will become apparent from the following description when taken in conjunction of the accompanying drawings, in which:

FIG. 1 is an exploded view of a water pump of a first embodiment of the present invention;

FIG. 2 is a front view of the water pump of the first embodiment of the present invention;

FIG. 3 is a sectional view taken along the line A-A of FIG. 2;

FIG. 4 is an enlarged sectional view of an essential portion of the water pump of the first embodiment;

FIG. 5 is a sectional view of a slinger that is usable as a part of a watertight construction employed in the water pump of the first embodiment;

FIG. 6 is a view similar to FIG. 5, but showing another slinger that is also usable as a part of the watertight construction employed in the water pump of the first embodiment;

FIG. 7 is a view similar to FIG. 4, but showing an essential portion of a water pump of a second embodiment of the present invention;

FIG. 8 is a view similar to FIG. 4, but showing an essential portion of a water pump of a third embodiment of the present invention; and

FIG. 9 is a view similar to FIG. 4, but showing an essential portion of a water pump of a fourth embodiment of the present invention.

DETAILED DESCRIPTION

In the following, water pumps of various embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The water pumps to which the following explanation is directed are of a type that is used for pumping a cooling water that circulates in an engine cooling system of a motor vehicle powered by an internal combustion engine. More specifically, the water pump is of a type that is mounted on a side wall of an engine block and powered by a crankshaft of the engine for circulating cooling water through a water jacket formed in the engine block.

In the following description, various directional terms, such as right, left, upper, lower, rightward and the like are used for ease of explanation. It is however to be noted that such terms are to be understood with respect to only a drawing or drawings on which a corresponding part or portion is shown.

Referring to FIGS. 1, 2, 3 and 4, particularly FIGS. 1 and 3, there is shown a water pump 1A of a first embodiment of the present invention.

As is seen from FIG. 1, water pump 1A comprises a pump housing 2 that has at its left side a cylindrical portion 11 and at its right side a flange portion 2a integrated with a right end of the cylindrical portion 11. Pump housing 2 is a cast product of aluminum alloy and fixed to a side surface of an engine block (not shown) through flange portion 2a thereby to form a pump chamber P (or volute chamber, see FIG. 3) between pump housing 2 and the engine block.

As is best seen from FIG. 3, a drive shaft 3 is rotatably and coaxially installed in pump housing 2 through an after-mentioned mechanical seal unit 10. Drive shaft 3 has a left end (in FIG. 3) that is projected outward or leftward from pump housing 2. To the projected left end of the drive shaft 3, there is fixed a central hollow portion 4c of a pulley 4. Although not shown in the drawing, a drive belt is put on pulley 4 to transmit a turning force (or torque) to drive shaft 3 from a crankshaft of the engine.

As is seen from FIGS. 1 and 3, a conical cover 5 is fixed to a left portion of pulley 4 in a manner to cover the substantially entire left surface of pulley 4, as shown.

As is best seen from FIG. 3, between pulley 4 and a smaller diameter end portion 11c of pump housing 2, there is concentrically disposed a ball bearing 6 to allow a smoothed rotation of pulley 4 around smaller diameter end portion 11e of pump housing 2. Ball bearing 6 comprises an inner race 16 fixed to smaller diameter end portion 11c, an outer race 17 fixed to pulley 4 and a plurality of balls 18 rotatably disposed between the inner and outer races 16 and 17.

As is seen from FIGS. 3 and 4, between pulley 4 and smaller diameter end portion 11c of pump housing 2, there is concentrically arranged an annular slinger 7 of which inner peripheral portion is fixed to the pump housing 2. As is best seen from FIG. 4, annular slinger 7 is oriented to face a right end of ball bearing 6. Due to provision of annular slinger 7, water penetration into ball bearing 6 is restrained for the reasons that will be described hereinafter.

Referring back to FIG. 3, drive shaft 3 has a right end to which the central hollow portion 8c of an impeller 8 is fixed. Thus, under rotation of drive shaft 3, impeller 8 is rotated in pump chamber P.

As is seen from FIG. 3, cylindrical portion 11 of pump housing 2 comprises a larger diameter portion 11a that is formed beside the above-mentioned flange portion 2a, an intermediate diameter portion 11b that extends leftward from larger diameter portion 11a through a radially extending annular portion (no numeral) and a smaller diameter end portion 11c that extends leftward from intermediate diameter portion 11b through a radially extending annular portion 11d. As shown, an inner diameter of smaller diameter end portion 11c gradually increases as a distance from the left end of the end portion 11c increases.

Below intermediate diameter portion lib in FIG. 3, there is defined a drain chamber 12 that communicates with an inside space of the portion 11b through a drain passage 13. Denoted by numeral 9 is a plug for sealing drain chamber 12.

As is seen from FIG. 3, between intermediate diameter portion 11b and drive shaft 3, there is concentrically disposed a mechanical seal unit 10 by which water penetration or invasion toward ball bearing 6 from pump chamber P is suppressed or at least minimized. However, since complete stopping of the water penetration toward ball bearing 6 is not effected by only the mechanical seal unit 10, the following water drain construction is provided.

That is, the water drain construction comprises the drain passage 13 that is formed in a thicker lower portion of intermediate diameter portion 11b to communicate the inside space of the portion 11b with drain chamber 12. That is, drain passage 13 extends along the Y-axis of FIG. 3. Due to provision of drain passage 13, cooling water that would penetrate into the inside space of intermediate diameter portion 11b from pump chamber P through the mechanical seal unit 10 is drained into drain chamber 12. Thus, water penetration toward the interior of smaller diameter end portion 11c is suppressed or at least minimized.

In addition to the above-mentioned drain passage 13, intermediate diameter portion 11b is formed, at a position diametrically opposite to the position of the drain passage 13, with a connecting opening 14 to communicate the interior of the portion 11b with the outside of pump housing 2. That is, connecting opening 14 extends along the Y-axis of FIG. 3. Due to provision of connecting opening 14, water vapor produced in drain chamber 12 can escape into the outside of pump housing 2.

Drive shaft 3 is made of a steel and rotatably disposed in pump housing 2 with its axially opposed ends projected outward from pump housing 2, as shown.

As is seen from FIG. 3, drive shaft 3 is formed at a portion thereof facing the drain passage 13 and connecting opening 14 with an annular groove 3a that has a given width. Due to provision of annular groove 3a, penetrating water on the outer surface of drive shaft 3 is suppressed from directly flowing toward the interior of smaller diameter end portion 11c. That is, the penetrating water is trapped by annular groove 3a and then led to drain chamber 12 through drain passage 13.

Pulley 4 is produced by pressing a steel plate and as is seen from FIG. 1, pulley 4 has a cylindrical shape.

As is seen from FIG. 3, pulley 4 comprises a tubular base portion 4a (or first tubular portion) that is shaped to surround the smaller diameter end portion 11c of pump housing 2, a belt putting rim portion 4b (or second tubular portion) that is shaped to surround tubular base portion 4a and integrally connected to tubular base portion 4a through an annular wall portion 4f and the above-mentioned central hollow portion 4c that is integrally connected to tubular base portion 4a through an annular wall portion 4e and fixed to the left end of drive shaft 3. As is seen from FIG. 3, for the fixing between pulley 4 and drive shaft 3, the left end of drive shaft 3 is press-fitted into the central hollow portion 4c of pulley 4.

As shown in FIG. 3, tubular base portion 4a of pulley 4 comprises a cylindrical wall 4d that is intimately and tightly disposed on outer race 17 of ball bearing 6 and the above-mentioned annular wall portion 4e. The wall portion 4e extends radially inward from a left end of cylindrical wall 4d to a right end of central hollow portion 4c. For the assembly, ball bearing 6 is press-fitted into tubular base portion 4a, and then, smaller diameter end portion 11c of pump housing 2 is press-fitted into ball bearing 6.

As will be understood from FIG. 3, annular wall portion 4e of pulley 4 is formed with a plurality of openings 15 through which the penetrating water in the interior of smaller diameter end portion 11c of pump housing 2 is discharged to the outside of water pump 1A. Openings 15 are arranged at evenly spaced intervals. Each opening 15 extends along the X-axis of FIG. 3.

Each opening 15 is so positioned and arranged as to place at least part thereof to a position where an inside end of an after-mentioned first annular seal member 19 and the inner race 16 of ball bearing 6 contact. More specifically, each opening 15 is arranged to substantially face the given contact portion between the first annular seal member 19 and the inner race 16. With this arrangement, the penetrating water or water vapor in the interior of smaller diameter end portion 11c is smoothly discharged into the outside through each opening 15 before arriving at the first annular seal member 19. Due to provision of plural openings 15, the water discharging from pump housing 2 is effectively carried out. Furthermore, since openings 15 are arranged to axially face inner race 16 of ball bearing 6, the openings 15 can be used as work assist openings for the tools that are manipulated or handled to place the ball bearing 6 onto an exact position of the smaller diameter end portion 11c.

The above-mentioned conical cover 5 is produced by pressing a corrosion-resistant metal plate, such as aluminum plate, stainless plate or the like.

As is seen from FIG. 3, conical cover 5 comprises a main cover portion 5a that covers tubular base portion 4a of pulley 4 and a central annular portion 5b that is tightly mounted on central hollow portion 4c of pulley 4 through press-fitting. As is seen, main cover portion 5a of conical cover 5 extends radially outwardly from central annular portion 5b to a position near an inside part of belt putting rim portion 4b of pulley 4. Due to provision of conical cover 5, direct penetration or invasion of water or foreign substances into pump housing 2 through openings 15 is suppressed.

The above-mentioned ball bearing 6 is of a single ball-row type with seal members. That is, ball bearing 6 is snugly disposed between an outer cylindrical surface of smaller diameter end portion 11c of pump housing 2 and an inner cylindrical surface of cylindrical wall 4d of pulley 4.

As is mentioned hereinabove, ball bearing 6 comprises inner race 16 that is press-fitted to the outer surface of smaller diameter end portion 11c, outer race 17 that is press-fitted to the inner surface of cylindrical wall 4d and a plurality of balls 18 that are rotatably and partially received in guide grooves (no numerals) respectively formed in inner and outer races 16 and 17.

As is seen from FIG. 3, ball bearing 6 is equipped with first and second annular seal members 19 and 20. These first and second annular seal members 19 and 20 are arranged at axially opposed ends of ball bearing 6 respectively in a manner to cover axially opposed open ends of an annular space (no numeral) defined by inner and outer races 16 and 17.

As will be understood from FIGS. 3 and 4, outer peripheries of first and second annular seal members 19 and 20 are fixed to axially opposed inside ends of outer race 17 by caulking, while, as will be described in detail hereinafter, inner peripheries of first and second annular seal members 19 and 20 are arranged to slide in grooves respectively formed in axially opposed inside ends of inner race 16. Due to provision of first annular seal member 19, water penetration from the interior of smaller diameter end portion 11c to the interior of ball bearing 6 is suppressed.

As is seen from FIG. 4, due to provision of second annular seal member 20 and the above-mentioned annular slinger 7 placed near second annular seal member 20, water penetration from the outside to the interior of ball bearing 6 is suppressed.

Since first and second annular seal members 19 and 20 have substantially the same construction, the following detailed description on the construction will be directed to only second annular seal member 20 for simplification of explanation.

As is seen from FIG. 4, second annular seal member 20 comprises an annular metal core member 20a and an annular rubber cover member 20x that covers an outer surface of annular metal core member 20a. The outer periphery of second annular seal member 20 is fixed to the inner end of outer race 17 by caulking, and the inner periphery of second annular seal member 20 is in contact with an inclined wall of an annular cut (no numeral) formed in the inner end of inner race 16.

That is, the inner periphery of second annular seal member 20 is shaped into a seal lip member 20b that includes first and second seal lips 20d and 20e. As shown, first and second seal lips 20d and 20e are parts of the rubber cover 20x and slidably and elastically pressed against the inclined wall of the annular cut of inner race 16.

Due to provision of seal lip member 20b elastically pressed against the inclined wall of inner race 16, there is produced a first sealing section S1 by which penetration or invasion of foreign substances from the outside into ball bearing 6 is suppressed. Due to provision of the two seal lips 20d and 20e, a so-called double sealing structure is defined by second annular seal member 20.

Since first annular seal member 19 (see FIG. 3) has the same structure as the above-mentioned second annular seal member 20, penetration or invasion of foreign substances into ball bearing 6 from the inner space of smaller diameter end portion 11c of pump housing 2 is suppressed.

As is best shown in FIG. 4, annular slinger 7 secured to pump housing 2 is arranged to face the right end of ball bearing 16. Annular slinger 7 comprises an annular metal core member 21 and an annular rubber cover member 22 that covers a radially outside portion of annular metal core member 21 except a left surface that faces second annular seal member 20. Annular metal core member 21 is made of a metal having a high thermal conductivity and suitable resiliency. One example of such metal is aluminum alloy.

As shown, annular slinger 7 has an inner peripheral portion 21a that is fixed to an outer surface of smaller diameter end portion 11c of pump housing 2 and an outer peripheral portion that is provided with an annular seal lip 23. The outer peripheral portion of annular slinger 7 is placed near an inner surface of cylindrical wall 4d of pulley 4. In FIG. 4, the space formed between the outer periphery of annular slinger 7 and the inner surface of cylindrical wall 4d is denoted by C1. As shown, s annular seal lip 23 is a part of rubber cover member 22 and slidably and elastically pressed against a right end surface of outer race 17.

As is seen from FIGS. 3 and 4, due to provision of annular seal lip 23, foreign substances from the outside and cooling water that would arrive thereto through connecting opening 14 from mechanical seal unit 10 are suppressed from invading the interior of ball bearing 6.

As is seen from FIG. 4, inner peripheral portion 21a of annular slinger 7, that is tightly disposed on the outer surface of smaller diameter end portion 11c of pump housing 2, is sandwiched between an annular ridge 11d′ formed on radially extending annular portion 11d of pump housing 2 and the right end of inner race 16 of ball bearing 6.

Thus, inner race 16 of ball bearing 6, annular slinger 7 and pump housing 2 constitute a first single unit which is fixed. It is to be noted that in FIG. 4, cylindrical wall 4d and outer race 17 constitute a second single unit that turns around the fixed first single unit.

As is seen from FIG. 4, the outer peripheral portion of annular slinger 7 is slightly depressed rightward and thus there is defined a given space C2 between the right end of ball bearing 6 and the outer peripheral portion of annular slinger 7. The space C2 is sealed by annular seal lip 23, as shown.

As is seen from FIGS. 3 and 4, radially extending annular portion 11d of pump housing 2 is formed with an annular groove 24 at a radially inside position of annular ridge 11d′. More specifically, as shown, the radially inside end of annular groove 24 is mated with the cylindrical outer surface of smaller diameter end portion 11c. With this arrangement, exact setting of the inner periphery of annular slinger 7 onto the cylindrical outer surface of smaller diameter end portion 11c is achieved. This is because the inner periphery of annular slinger 7 can have an increased flexibility in selecting the best set position due to provision of annular groove. If such annular groove 24 is not provided, the flexibility in selecting the best set position for the inner periphery of annular slinger 7 would be lowered. That is, due to provision of annular groove 24, annular slinger 7 can be exactly and tightly disposed on smaller diameter end portion 11c of pump housing 2 without rattle.

Annular seal lip 24 is so sized and constructed as to be sufficiently pressed against the right end of outer race 17 even when a certain displacement is taken place by outer race 17 under operation of the water pump 1A. The displaced positions of outer race 17 are shown by broken lines in FIG. 4.

Due to provision of annular seal lip 24 elastically pressed against the right end of outer race 17, there is provided a second sealing section S2 by which invasion of foreign substances from the outside into the space C2 and thus into ball bearing 6 is suppressed.

As is seen from FIGS. 1, 2 and 3, particularly FIG. 2, the above-mentioned impeller 8 is fixed at its central hollow portion 8c to the projected right end of drive shaft 3. Like pulley 4, impeller 8 is produced by pressing a steel plate and has an integrated structure.

As is well shown in FIGS. 2 and 3, impeller 8 comprises an annular base portion 8a, a plurality of vanes 8b pressed out of a peripheral portion of annular base portion 8a and the above-mentioned central hollow portion 8c.

As is described in detail hereinabove, in water pump 1A according to the present invention, there are arranged two, viz., first and second sealing sections S1 and S2 in series in a passage that extends from the outside (or water drain chamber 12) to the interior of ball bearing 6. Furthermore, in water pump 1A, there is further arranged a third sealing section that is constructed by first annular seal member 19 (see FIG. 3) and arranged in a passage that extends from the outside to the interior of ball bearing 6 through openings 15 of pulley 4. Accordingly, invasion or penetration of foreign substances and water into the interior of ball bearing 6 is quite effectively suppressed.

In the following, conspicuous effects of water pump 1A of the first embodiment of the present invention will be described with the aid of FIGS. 3 and 4.

Due to the nature of water pump 1A having the above-mentioned construction, there is inevitably formed a first given space SP1 (see FIG. 4) defined by pulley 4, ball bearing 6 and is annular slinger 7. Thus, under operation of water pump 1A, first given space SP1 tends to collect therein leaked cooling water from connecting opening 14 (see FIG. 3) and foreign substances from the outside.

However, for the following reasons, such tendency is suppressed or at least minimized. That is, as is seen from FIG. 3, upon starting of the associated engine, pulley 4 is turned around the fixed smaller diameter end portion 11c of pump housing 2 and thus, as is seen from FIG. 4, outer race 17 of ball bearing 6, which is secured to pulley 4, turns around the axis of drive shaft 3 keeping a contact of the right end surface thereof with annular seal lip 23 of slinger 7. Due to frictional heat produced by the sliding contact between the right end surface of outer race 17 and annular seal lip 23, water collected in first given space SP1 is evaporated and thus removed therefrom. This reduces the possibility of leakage of water through second sealing section S2. If the leading end of annular seal lip 23 is arranged to contact a radially outer side of the right end surface of outer race 17 as shown in FIG. 4, the frictional heat is much effectively produced due to an increased speed with which the leading end of annular seal lip 23 contacts the right end surface of outer race 17. Of course, in this case, water evaporation is much effectively made.

In addition to the above, heat transmitted to annular slinger 7 from pump housing 2 promotes the above-mentioned water evaporation. That is, cooling water pumped up by water pump 1A is led to the engine block for cooling the engine, and thus, the cooling water is heated by the engine block before rerunning to water pump 1A. This means that under operation of water pump 1A, pump housing 2 that defines pump chamber P therein is heated to a certain level and thus annular slinger 7 connected to pump housing 2 is also heated by the heat transfer from heated pump housing 2. Heating of annular slinger 7 induces heating of annular seal lip 23, which promotes the water is evaporation at first given space SP1.

Even if the water (viz., cooling water or foreign substances) passes through the second sealing section S2 and enters into a second given space SP2 (see FIG. 4) that is defined by annular slinger 7, annular seal lip 23, the right end surface of outer roller 17 and second annular seal member 20, the water in second given space SP2 is evaporated by the heat transmitted to annular slinger 7 and inner race 16 of ball bearing 6 from pump housing 2. That is, even if water leaks into second given space SP2 from first given space SP1, the possibility of inversion or penetration of water into the interior of ball bearing 6 is quite small.

Because annular slinger 7 is of a fixed member, the slinger 7 is not subjected to “cooling by wind” that would be induced if annular slinger 7 rotates, and thus, the heat accumulated in annular slinger 7 is not lost fast. That is, in the first embodiment, the heat transmitted to annular slinger 7 is effectively used for evaporating water.

As is described hereinabove, in water pump 1A of the first embodiment of the present invention, due to provision of annular seal lip 23, invasion and penetration of foreign substances and water from the outside and connecting passage 14 toward second given space SP2 facing second annular seal member 20 are suppressed or at least minimized. Furthermore, by the frictional heat produced under operation of water pump 1A, the water staying near second sealing section S2 is effectively evaporated. Thus, undesired invasion or penetration of such foreign substances and water into the interior of ball bearing 6 is suppressed or at least minimized.

Even if water happens to leak into second given space SP2 through second sealing section S2, the heat produced under operation of water pump 1A functions to evaporate the water and thus suppresses or at least minimizes the possibility of invasion or penetration of water into the interior of ball bearing 6.

Because of the above-mentioned effective watertight construction for ball bearing 6, there is no need of using a high precision ball bearing, such as the ball bearing having two rows of balls between inner and outer races. Thus, production cost can be reduced in the water pump of the invention.

Referring to FIGS. 5 and 6, there are shown modifications of annular slinger 7, which are usable in water pump 1A of the first embodiment.

In the modification of FIG. 5, only a peripheral portion of annular metal core member 21 is covered with the rubber cover member 22, as shown. For a tight mounting of rubber cover member 22 onto the metal core member 21, the peripheral portion of the metal core member 21 is formed with a plurality of openings 21b through which material of the rubber cover member 22 runs.

In the modification of FIG. 6, an entire construction of annular metal core member 21 is covered with the rubber cover member 22, as shown. In this modification, the annular metal core member 21 is protected from corrosion.

Referring to FIG. 7, there is shown an essential portion of a water pump 1B of a second embodiment of the present invention.

As shown, in this second embodiment, the annular seal lip 23 of annular slinger 7 extends radially outward to slidably contact to an inner surface of a junction portion 4x (see FIG. 3) between tubular base portion 4a and annular wall portion 4f of pulley 4.

In this second embodiment 1B, substantially the same effects as those of the above-mentioned first embodiment 1A are obtained due to similar construction therebetween. However, in this second embodiment 1B, the frictional heat produced by the sliding contact between the junction portion 4x of pulley 4 and annular seal lip 23 is higher than that produced in the first embodiment 1A since the junction portion 4x provides the annular seal lip 23 with a much longer running way per each turning of pulley 4. This means that the water staying at and near second sealing section S2 is much effectively evaporated.

Furthermore, in water pump 1B of this second embodiment, there is no space that corresponds to the first given space SP1 of the first embodiment 1A. Thus, the possibility of leakage of water through second sealing section S2 is lowered.

Referring to FIG. 8, there is shown an essential portion of a water pump 1C of a third embodiment of the present invention.

As shown, in this third embodiment, the annular slinger 7 has no rubber cover member disposed thereon, and annular rubber cover member 20x of second annular seal member 20 is formed with an annular seal lip 24 that extends radially outward to slidably contact to an inner surface 7a of the naked annular slinger 7.

Because of the naked structure of annular slinger 7, the heat transmitted thereto from pump housing 2 is much effectively used for producing the frictional heat by the sliding contact of annular seal lip 24 with annular slinger 7. Thus, water staying at and near second sealing section S2 is much effectively evaporated.

Referring to FIG. 9, there is shown an essential portion of a water pump 1D of a fourth embodiment of the present invention.

As shown, in this fourth embodiment, the annular slinger 7 has no rubber cover member disposed thereon and an annular dry film coat (or annular solid lubricant film) 25 is formed on a peripheral part of the inner surface 7a of the naked annular slinger 7. As shown, a major surface of annular dry film coat 25 is in contact with the right end surface of outer race 17 of ball bearing 6. Due to the resiliency possessed by naked annular slinger 7, the major surface of annular dry film coat 25 is pressed against the right end surface of the outer race 17.

Due to usage of annular dry film coat 25 that is pressed against the right end surface of outer race 17 of ball bearing 6, second sealing section S2 can exhibit an excellent sealing function against water and foreign substances.

If desired, following modifications may be applied to the water pumps of the above-mentioned embodiments.

That is, if desired, grease may be applied to the top of annular seal lip 23 or 24 for promoting the water stopping function of the seal lip and increasing the durability of the seal lip against the friction in case of water pumps 1A, 1B and 1C of the first, second and third embodiments.

Furthermore, if desired, besides the above-mentioned water/foreign substances stopping structure including annular slinger 7 and annular seal lip 23 or 24 or annular dry film coat 25, a structure similar to the water/foreign substances stopping structure may be applied to a left side of ball bearing 6 (see FIG. 3).

Furthermore, if desired, another water stopping structure may be employed in water pumps 1A, 1B, 1C and 1D. That is, the water stopping structure comprises an annular seal lip (not shown) that is mounted on conical cover 5 (see FIG. 3) and has a leading end pressed against an inner surface of belt putting rim portion 4b of pulley 4 or an outer surface of cylindrical wall 4d of pulley. With such water stopping structure, a space S3 defined between a periphery of conical cover 5 and the inner surface of belt putting rim portion 4b is substantially closed, and thus, invasion of water into ball bearing 6 through openings 15 is suppressed or at least minimized.

The entire contents of Japanese Patent Application 2011-132180 filed Jun. 14, 2011 are incorporated herein by reference.

Although the invention has been described above with reference to embodiments of the invention, the invention is not limited to such embodiments as described above. Various modifications and variations of such embodiments may be carried out by those skilled in the art, in light of the above description.