Self-aligning universal joint assembly for a stern drive

[0002] The present invention is generally related to marine propulsion systems, and, more particularly, the present invention is related to a stern drive system and techniques using a universal joint (U-joint) assembly having an alignment subassembly that facilitates assemblage of a vertical drive unit to a mount assembly that extends through the transom of a boat.

[0003] Although marine propulsion systems, such as stern drives, provide versatile and proficient means of propulsion to pleasure boats, etc., typical stern drive systems have presented some assemblage challenges to boat manufacturers and servicing personnel, such as assemblage of their vertical drive unit or outdrive to the transom mount assembly.

[0004] FIG. 1 illustrates a typical vertical drive unit 30 having a U-joint 27 with a U-joint shaft 28 which, as will be readily understood by those skilled in the art, needs to be sufficiently long to extend through the transom mount assembly to engage an engine coupler 23 (FIG. 2) connected to receive driving power from an engine crankshaft. The challenges arise since aligning the relatively long U-joint shaft attached to the vertical drive unit relative to the engine coupler is not easy. For example, the engine coupler may not be readily visible during assembly operations, and thus, engine position becomes very critical to ensure the alignment required to provide a lasting and trouble-free mechanical connection. Although engine alignment tools have been used to attempt to provide proper alignment of the engine relative to the U-joint, such tools have only been partially effective being that they add to the cost and time of engine installation, and the assemblage process from time to time may require reinstallation of the engine even when using such tools.

[0005] In view of the above-described difficulties, it would be desirable to provide an assembly that provides a relatively shorter U-joint shaft that can be readily placed into an alignment position without having to depend on the burdensome engine alignment operations generally used heretofore. It is further desirable to provide a kit that facilitates assemblage of the outdrive to a gimbal housing that houses a U-joint for pivotally engaging the outdrive to the gimbal housing. It is still desirable to provide techniques for facilitating assemblage of the outdrive to the gimbal housing.

[0006] Generally speaking, the present invention fulfills the foregoing needs by providing in one embodiment a propulsion system that extends through a boat transom and comprises an engine, a gimbal housing, and a drive unit. The propulsion system further comprises a universal joint (U-joint) in the gimbal housing for pivotally engaging the drive unit to the gimbal housing. The U-joint includes an input shaft that receives power from the engine and an output shaft connectable to the drive unit. An alignment assembly is configured to support the U-joint in an alignment position while its output shaft is being connected to the drive unit.

[0007] The present invention may further fulfill the foregoing needs by providing an assembly for facilitating assemblage of a drive unit to a gimbal housing in a boat. The assembly comprises a universal joint (U-joint) in the gimbal housing for pivotally engaging the drive unit to the gimbal housing. The U-joint includes an input shaft that receives driving power and an output shaft connectable to the drive unit. The assembly further comprises an alignment subassembly configured to support the U-joint in an alignment position while its output shaft is being connected to the drive unit.

[0008] In another aspect of the invention, a method is provided for facilitating assemblage of a drive unit to a gimbal housing in a boat using a universal joint (U-joint) in the gimbal housing for pivotally engaging the drive unit to the gimbal housing. The U-joint includes an input shaft that receives driving power and an output shaft connectable to the drive unit. The method allows for providing an alignment assembly. The method further allows for positioning the alignment assembly to support the U-joint in an alignment position while its output shaft is being connected to the drive unit.

[0009] FIG. 1 shows an elevational side view of a typical vertical drive unit that may have presented some assemblage issues in view of its relatively long drive shaft;

[0010] FIG. 2 shows a fragmentary cross-sectional side view of an exemplary marine propulsion prior to assemblage of an outdrive to a U-joint assembly embodying the present invention;

[0011] FIG. 3 shows the marine propulsion system of FIG. 2 subsequent to assemblage of the outdrive to the U-joint assembly;

[0012] FIG. 4 is a cross-sectional view of one exemplary single-piece embodiment of the alignment assembly of the present invention; and

[0013] FIG. 5 is a cross-sectional view of one exemplary multi-piece embodiment of the alignment assembly of the present invention.

[0014] Before any embodiment of the invention is explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

[0015] FIG. 2 shows an exemplary marine propulsion system 10 prior to assemblage of its outdrive to a U-joint coupler and which assemblage is substantially facilitated by the alignment assembly of the present invention. Marine propulsion system 10 is illustrated in FIG. 2 as having an engine 12 located within a boat having a transom 22. Standard engine mounts 18 may attach the engine 12 to the boat. The engine 12 provides power through a crankshaft rotating at an engine revolution rate and outputs power to a drive shaft 20. The drive shaft 20 either extends through or is coupled through the transom 22 of the boat. A gimbal housing 24 may extend through the transom 22 to be supported by engine 12 at a suitable mounting flange 21. As will be readily understood by those skilled in the art, the gimbal housing supports a gimbal unit 25, such as may be made up of a pivot housing and a gimbal ring. Gimbal unit 25 is horizontally pivotable to provide steering to the boat in a desired direction of travel and is further vertically pivotable to provide, for example, a desired trim relative to the water plane over which the boat travels. Gimbal unit 25 accommodates a universal joint 27 comprising at one end thereof an input shaft, e.g., drive shaft 20, and comprising at an opposite end an output shaft 28 connectable, as shown in FIG. 3, to a vertical drive unit or outdrive 30 for allowing the vertical and horizontal pivoting. Standard gears and driveshafts within outdrive 30 in operation cooperate to transmit the power from the output shaft 28 to a propeller shaft located in a lower gearcase 32 appended at the lower end of drive unit 30. Such operation is well-known to those of ordinary skill in the art and need not be described in any greater detail for purposes of the present invention.

[0016] FIG. 4 illustrates one exemplary embodiment of an alignment assembly 50 configured to support U-joint 27 in an alignment position while its output shaft 28 is being connected to drive unit 30. As shown in FIG. 4, and as will be readily understood by those skilled in the art, a bellows enclosure 52, preferably a flexible bellows enclosure made up of a suitable standard rubber material, encloses or encircles the U-joint coupling and may be secured at a proximate end (not shown) relative to the boat transom using standard transom sealing techniques. As shown in FIGS. 4 and 5, a distal end 54 of the bellows enclosure relative to the boat transom is used for supporting alignment assembly 50.

[0017] The exemplary embodiment of alignment assembly 50 comprises a single piece assembly having inner and outer sections 56 and 58, such as co-axially disposed cylindrical sections. In particular, inner section 56 is configured to support U-joint 27 in the alignment position while output shaft 28 is being connected to drive unit 30. Outer section 58 of assembly 50 is configured to be axially slideable relative to bellows enclosure 52 so that inner section 56 is free from interference with U-joint 27 during rotational operation of U-joint 27 and associated components. For example, outer section 58 should have a diameter dimensioned sufficiently wide to provide relatively comfortable snug interference fit with bellows enclosure 52 so that the inner section of the single-piece assembly supports the U-joint in the alignment position while being connected to the drive unit. Further, the diameter of outer section 58 should be dimensioned sufficiently narrow to permit axially slideable movement relative to bellows enclosure 52 so that its inner section 56 is free from interference with U-joint 27 during rotational operation.

[0018] FIG. 5 illustrates another exemplary embodiment of assembly 50 made up of multiple pieces, such as a U-joint support piece 60, a bellows retainer piece 62 and a seal 64. As shown in FIG. 5, U-joint support piece 60 comprises an outer surface 66, such as a cylindrical outer surface, supported by a shoulder 68 in gimbal unit 25. U-joint support piece 60 further comprises an inner surface 70, which may also be a cylindrical surface, for supporting U-joint 27 in the alignment position while being connected to vertical drive unit 30. As shown in FIG. 5, shoulder 68 may include a surface 72 positioned to engage a similarly configured corresponding surface 74 in the distal end of bellows enclosure 52.

[0019] As further shown in FIG. 5, bellows retainer section 62 is configured to be positioned between bellows 52, shoulder 68 and U-joint support piece 60 to ensure bellows engagement even though outer surface 66 of support piece 60 is axially slideable relative to shoulder 68 so that inner surface 70 is free from interference with U-joint 27 during rotational operation of U-joint 27 and associated components. It will be appreciated that either of the embodiments of alignment assembly 50 shown in FIGS. 4 and 5 may be made of a suitable rigid and dimensionally stable polymer material, such as plastic. It will be appreciated, however, that the alignment assembly need not be limited to polymers being that other materials including metal, metal alloys, etc., could be employed, if so desired.

[0020] While the preferred embodiments of the present invention have been shown and described herein, it will be obvious that such embodiments are provided by way of example only. Numerous variations, changes and substitutions will occur to those of skill in the art without departing from the invention herein. Accordingly, it is intended that the invention be limited only by the spirit and scope of the appended claims.