Water Pump

1. Field of the Invention

This invention relates to a water pump for circulating engine cooling water in an automotive vehicle or the like.

2. Description of the Prior Art

Water pumps for circulating engine cooling water which have heretofore been widely used are generally of a structure in which an impeller is disposed on a portion of a rotary shaft rotatably supported in a housing fixed to an engine block through a bearing portion which extends into the engine block, and a pulley is disposed on the opposite side. The bearing portion is formed by an inner race, an outer race and rolling members interposed therebetween.

In recent years, due to the necessity of making the vehicle lightweight and making the vehicle compact for the saving of space, development of a compact, lightweight water pump has been desired, and an example, of such a pump is disclosed in Japanese Laid-open Utility Model Application No. 592/1984. The water pump described in said publication has achieved a reduction in number of parts and compactness by forming a rotary shaft 102 integrally with a pulley and forming a housing 104 and an outer race for a bearing integrally with each other, as shown in FIG. 4 of the accompanying drawings.

However, in the water pump described in the aforementioned publication, the housing 104 has a track surface for the rolling members 103 of the bearing and therefore must be made of steel for bearing against the rotating members. In this case, the housing 104 contacts the engine cooling water and the water entering the engine compartment and suffers from the problem of rusting. Therefore, it is necessary to subject the housing to a special surface treatment in order to prevent rusting. Further, since the housing 104 is formed of steel which has a specific gravity greater than aluminum heretofore used, no significant improvement can be obtained in terms of reducing the weight.

Also, the dimensions of the mounting portion of the housing 104 with respect to the engine body differ from vehicle to vehicle. Therefore, the housing 104 must be set in conformity with each vehicle individually even though the dimensions of the track portion of the bearing can be made common, and this is unsuitable for mass production.

It is an object of the present invention to provide a water pump which can be made compact and lightweight while maintaining the bearing portion common to a range of vehicles.

The present invention has been devised to solve the above-noted problems and provides a water pump comprising a rotary shaft having a water circulating impeller fixed to one end thereof and a rotative driving pulley fixed to the other end thereof, a housing made of resin and having an outer shell portion covering the portion of said rotary shaft between the opposite ends thereof and a mounting portion extending radially outwardly from the outer periphery of said outer shall portion which is proximate to said impeller, a plurality of rolling members disposed between said rotary shaft and said housing to enable rotation of said rotary shaft, an outer race disposed between said housing and said rolling members and providing an outer track surface for said rolling members, and seal means for preventing entry of foreign substances from the axial opposite ends of said outer race.

The water pump of the present invention achieves compactness and reduced weight by the housing made of resin while forming the bearing portion by parts common to a diversity of vehicles.

FIG. 1 is a cross-sectional view of a water pump according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of a second embodiment of the present invention.

FIG. 3 is a cross-sectional view of a third embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a water pump according to the prior art.

Some embodiments of the present invention will hereinafter be described with reference to the drawings.

Referring to FIG. 1 which shows a first embodiment of the present invention, a rotary shaft 2 is rotatably journalled to a housing 3 through a bearing portion 1. An impeller, indicated diagrammatically by dot-dash lines, is fixedly fitted to one end of the rotary shaft 2 which extends into an engine block, and circulates the water in the engine block during rotation. A pulley, also indicated diagrammatically, is fixed to the other end of the rotary shaft 2, i.e., the end which extends out into an engine compartment. The pulley is connected to a pulley on the rotary shaft of the engine through an endless belt and therefore, as the engine rotates, the rotary shaft 2 also rotates. The rotary shaft 2 serves also as the inner race of the bearing portion 1 and provides a track for rolling member 6. It will be understood that although not shown in later described embodiments, an impeller and pulley are similarly presumed present.

An outer race 8 forming the bearing portion 1 is integrally molded with the housing 3 and provides an outer track for the rolling members 6. Seals 10 and 12 are disposed at the opposite ends of the outer race 8 to prevent entry of foreign substances such as water and dust into the bearing portion 1. A mechanical seal 14 is disposed between that portion of the housing 3 which is adjacent to the impeller and the rotary shaft 2 additionally to prevent entry of water from the pump chamber of the engine block into the bearing portion 1.

The housing 3 is integrally molded with the outer race 8, and comprises an outer shell coaxial with the rotary shaft 2 and surrounding the outside thereof, and a mounting portion for mounting the rotary shaft on the engine block. A plurality of drip holes 5 are provided between the mechanical seal 14 of the housing 3 and the seal 12. Also, the housing 3 is fixed to the engine block through a mounting hole 4 in the mounting portion.

The housing 3 is suitably formed of 6--6 nylon with glass fiber of 20-50% or carbon fiber of 5-50% mixed thereto, but may also be formed of one of other various synthetic resins such as polyamide and polyester.

FIG. 2 shows a second embodiment of the present invention. In this embodiment, as compared with the first embodiment, the outer race is provided with an extending portion extending to the impeller side of the rotary shaft 2. In FIG. 2, members similar to those in FIG. 1 are given similar reference numerals and need not be described. A housing 13 is integrally molded with an outer race 18 and rotatably supports the rotary shaft 2 through rolling members 6.

The outer race 18, the rotary shaft 2 and the rolling members 6, define a bearing portion 11. The outer race 18 provides an outer track surface, and the portion of the outer race extending to the vicinity of the bearing surface on the engine block side serves also as a reinforcing member for the housing 13. Holes are formed at several locations in the extending portion and a drain hole 5 is also provided in the housing so as to discharge water which has entered between the mechanical seal 14 and the bearing seal 12.

FIG. 3 shows a third embodiment of the present invention. In this embodiment, a reinforcing insert 30 having the extending portion of the outer race of the second embodiment as a separate member is added. The rotary shaft 2, the rolling members 6 and the outer race 8 together constitute the bearing portion 1, and a reinforcing insert 30 of substantially L-shaped cross-section is fixed to the outer race 8 by a suitable fixing method such as press-fitting and reinforces a housing 23. The reinforcing insert 30 extends toward the engine block or housing (indicated diagrammatically in dashed lines in FIG. 1) axially of the rotary shaft 2 and extends out in the direction of a right angle, namely, radially outwardly relative to the rotary shaft 2, in the vicinity of the surface thereof which bears against the engine block. A mounting hole 24 in the housing 23 is reinforced circumferentially by the reinforcing insert 30 and is of a structure which prevents loosening of a bolt after tightening and therefore, it is not necessary to insert a part such as a bushing later.

The present embodiment is of a construction in which the outer race 8 can be used regardless of variations in mounting bolt pitch or the shape of the mounting portion from vehicle to vehicle. Again in the present embodiment, as in the second embodiment, a drain hole 5 for water discharge is provided.