Strut mounted gear box for counter rotating propellers

Abstract

A strut mounted gear box for counter rotating propellers. The gear box is strut mounted for securement to the hull of a boat. A main input shaft is coupled to a propulsion component of a boat with a distal end secured to an idler gear cage assembly located within the gear box. The main input shaft transfers torque and rotation from the propulsion component to an idler gear cage assembly. An inner tail shaft is coupled to the main input shaft and arranged to rotate the inner tail shaft in a first direction. A counter shaft is coupled to the idler gear cage assembly and arranged to rotate the counter shaft in a second direction. A first propeller is secured to the inner tail shaft providing rotation in the first direction; and a second propeller is secured to the counter shaft allowing rotation in the second direction.

Claims

1. A strut mounted gear box for counter rotating propellers comprising: a gear box (4), said gear box (4) having a conical shaped housing with a strut (32) extending from a side surface (34), said strut (32) secured to the hull (36) of a boat; a main input shaft (2) having a proximal end (38) coupled to a propulsion component (50) and a distal end (40) secured to a idler gear cage assembly (30) located within said gear box (4), said main input shaft (2) for transferring torque and rotation from the propulsion component (50) to the idler gear cage assembly (30); a inner tail shaft (16) coupled to said main input shaft (2) arranged to rotate said inner tail shaft (16) in a first direction; a counter shaft (15) coupled to said idler gear cage assembly (30) constructed and arranged to rotate said counter shaft (15) in a second direction; a first propeller (60) secured to said inner tail shaft (16) providing rotation in the first direction; and a second propeller (62) secured to the counter shaft (15) having rotation in the second direction.

2. The strut mounted gear box for counter rotating propellers according to claim 1 wherein said main input shaft is positioned inside an outer shaft casing.

3. The strut mounted gear box for counter rotating propellers according to claim 2 wherein said outer shaft casing is filled with a lubricant.

4. The strut mounted gear box for counter rotating propellers according to claim 2 wherein said outer shaft casing is coupled to the gear case with an input shaft spline adapter.

5. The strut mounted gear box for counter rotating propellers according to claim 1 wherein said first direction is clockwise and said second direction is counter-clockwise.

6. The strut mounted gear box for counter rotating propellers according to claim 1 wherein said first direction is counter-clockwise and said second direction is clockwise.

7. The strut mounted gear box for counter rotating propellers according to claim 1 wherein a bevel gear is attached to said distal end of said main input shaft, said bevel gear engaging spaced apart idler gears of said idler gear cage assembly, said spaced apart idler gears engaging a counter shaft driven bevel gear to allow counter rotation of said counter shaft.

8. The strut mounted gear box for counter rotating propellers according to claim 7 wherein idler gears are spaced apart by an Idler gear cage, said idler gear cage secured to a idler assembly carrier and held stationary within said gear case.

9. The strut mounted gear box for counter rotating propellers according to claim 1 wherein said counter shaft is centered on said inner tail shaft and thrusts against a forward needle thrust bearing.

10. The strut mounted gear box for counter rotating propellers according to claim 1 wherein thrust is delivered through a tail shaft collar which is directly coupled through a shaft adapter to said input shaft.

Description

DESCRIPTION OF THE DRAWINGS

[0025] FIG. 1 is a pictorial side view of the conventional transmission coupled to the strut mounted gear case;

[0026] FIG. 2 is a side view of the tail shaft collar; and

[0027] FIG. 3 is an exploded view of the strut mounted gear case.

DETAILED DESCRIPTION OF THE INVENTION

[0028] In this particular application and for illustrative purposes, this specification is based on a highly efficient, enclosed, fully oil lubricated system that is widely available on the pleasure market. This approach is considered the best and simplest approach to adding a counter rotation gear case, but is not limited to this configuration; it can also be used with conventional exposed shaft systems or any conventional shaft application. The system can also be used with a shroud around the propellers, thereby creating a thrustor, making it a good high thrust system for commercial use. The shroud can also pivot and provide steerage.

[0029] Referring now to the drawings, illustrated is a main input shaft (2) providing a solid shaft run from a propulsion unit (50) in a boat to a strut gear case (4). The main input shaft (2) is positioned inside an outer shaft casing (1) and coupled to the gear case with an input shaft spline adapter (3). The outer shaft casing (1) is filled with lubricant which lubricates the strut gear case (3). The input shaft (2) is supported as it enters the gear case (4) by a heavy duty needle roller bearing (6) with a support bearing inner ring (5) on an input end and a input bevel drive gear (7) on an opposite end. The Input shaft (2) terminates with the spline adapter (3) to accept the bevel drive gear (7). The bevel drive gear (7) is constructed and arranged to engage an idler gear assembly (30) consisting of two opposed and evenly spaced sets of idler gears (9) positioned perpendicular to and mating with the Bevel drive gear (7) by an idler gear cage (8), with idler gears (9) coupled to the idler gear cage (8) by idler gear shafts (11) using idler gear bearings (10) to allow rotation. Idler gears (9), bearings (10), and idler gear shafts (11) are positioned by the Idler gear cage (8).

[0030] The idler gear cage assembly (30) is positioned within idler assembly carrier (12) within the gear case (4) using either a pin, key or otherwise mechanically located in a manner sufficient to hold the idler assembly carrier (12) stationary to the gear case (4). A counter shaft (15) is centered on the inner tail shaft (16) and thrusts against a forward needle thrust bearing (13). The thrust bearing (13) is against the nose of the counter shaft (15) ahead of a driven bevel gear (14) located and mechanically fixed at the forward end of the counter shaft (15). Thrust is in turn delivered through a tail shaft collar 13a which is directly coupled through the shaft adapter (3) and input shaft (2). In this manner all forward thrust from both shafts is delivered up the main Input shaft (2) to the thrust bearings inside the vessel as would be the case with any traditional fixed shaft system.

[0031] The counter shaft driven bevel gear (14) in turn meshes with the two idler gears (9) in the idler gear assembly (30) which are driven by the input bevel drive gear (7). The counter shaft (15) is supported and kept aligned to the gear case (4) by the counter shaft needle support bearing (19).

[0032] The propeller end (24) of the inner tail shaft (16) is supported within the counter shaft (15) by a tail shaft needle support bearing (22). The tail shaft (16) is retained in position at the forward end under reverse thrust by a machined part of the shaft forming a collar (13a) which bears against the counter shaft needle thrust bearing (13) and thereby the forward nose of the counter shaft (15). The counter shaft (15) is retained in position at the driven bevel gear (14) by the reverse taper thrust bearing (17), the reverse thrust collar (18) and seal plate (21).

[0033] The seal plate (21) is male threaded on the outer surface so as to mate with corresponding female threads machined inside the end of the gear case (4). The seal plate (21) is sealed to the gear case with an O-ring behind the outside thread (not shown). The reverse thrust collar houses the outer race or cup of the tapered reverse thrust bearing (17) as well as the counter shaft needle support bearing (19). The seal plate (21) houses the two rubber lip style oil and water seals (20) sealing the main gear case (4) to the counter shaft (15).

[0034] The counter shaft (15) houses the tail shaft support bearing (22) and the two rubber lip style oil and water seals (23). All reverse thrust applied is captured by the input shaft casing (1) and delivered to the shaft mounting system within the vessel itself. No thrust in either direction would be transferred to the shaft strut bracket or its mounting system. Achieving counter rotation at the strut gear case allows for a very simple and compact gear train within the gear case itself.

[0035] Common bevel or miter gears can be used, by driving the beveled counter shaft gear through intermediate idler gears produces a differential type gear cluster which by nature reverses the direction of rotation in the counter shaft from the input shaft as long as the idler gear carrier assembly is held fixed. This approach also allows the inclusion of two or more identical idler gears, the total gear train power capacity increasing by the number of idler gears sharing the load applied without changing the size of the driver/driven gears. This system will increase the overall propulsive efficiency by at least 20% over conventional systems as well as over the previously described Outdrive, Pod or outboard versions.

[0036] The strut mounted gear box for counter rotating propellers comprising: a gear box (4), said gear box (4) having a conical shaped housing with a strut (32) extending from a side surface (34), said strut (32) secured to the hull (36) of a boat; a main input shaft (2) having a proximal end (38) coupled to a propulsion component (50) and a distal end (40) secured to a idler gear cage assembly (30) located within said gear box (4), said main input shaft (2) for transferring torque and rotation from the propulsion component (50) to the idler gear cage assembly (30); a inner tail shaft (16) coupled to said main input shaft (2) arranged to rotate said inner tail shaft (16) in a first direction; a counter shaft (15) coupled to said idler gear cage assembly (30) constructed and arranged to rotate said counter shaft (15) in a second direction; a first propeller (60) secured to said inner tail shaft (16) providing rotation in the first direction; and a second propeller (62) secured to the counter shaft (15) having rotation in the second direction.

[0037] It is to be understood that while a certain form of the invention is illustrated, it is not to be limited to the specific form or arrangement herein described and shown. It will be apparent to those skilled in the art that various changes may be made without departing from the scope of the invention, and that the invention is not to be considered limited to what is shown and described in the specification and any drawings/figures included herein.

[0038] One skilled in the art will readily appreciate that the present invention is well adapted to carry out the objectives and obtain the ends and advantages mentioned, as well as those inherent therein. The embodiments, methods, procedures and techniques described herein are presently representative of the preferred embodiments, are intended to be exemplary, and are not intended as limitations on the scope. Changes therein and other uses will occur to those skilled in the art which are encompassed within the spirit of the invention and are defined by the scope of the appended claims. Although the invention has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. Indeed, various modifications of the described modes for carrying out the invention which are obvious to those skilled in the art are intended to be within the scope of the following claims.