Planetary gear trains are supplied with a lubricant such as oil to reduce friction as well as provide protection from wear of components that come into relative contact such as gear teeth and bearing surfaces. Additionally, the lubricant is an acceptable medium to remove heat from such components. Increasing the cooling by increasing the volume of oil through a bearing increases the maximum speed of the bearing.
In most planetary gear train applications, the planetary gears have the highest rotational speed. Due to this fact, it is most critical to adequately lubricate the rolling elements or planetary bearings to allow the planetary gears to rotate freely. In applications where the planet rotational speed is relatively low, a passive manner of lubricating the planet bearings is adequate. However, when either the relative speed or the load is high, some designs employ a forced lubrication scheme and inject lubricant into the planetary bearings under pressure. Still others employ a combination of the two foregoing techniques by employing channels that collect the oil and then distribute the oil to the planetary gear system by using the centrifugal force on oil leaving a rotating component. Some such prior art designs utilize features to collect and/or distribute the oil that are machined into a carrier for the planet gears.
Any feature that can be cast and not require machining reduces both material and machine time cost. In view of the foregoing, it should be appreciated that it is desirable to provide a lubrication system for collecting and distributing lubricant for planetary gears that utilizes molded oil collection and molded oil channeling or distributing features. This permits a lower system cost than if either or both of these features required machining.
Increasing the amount of lubrication to the planet bearings also enables a reduction in size and weight of the planetary gear set. Furthermore, additional desirable features will become apparent to one skilled in the art from the foregoing background of the invention and the following detailed description of the preferred exemplary embodiments and the appended claims.