Abstract:
A marine propulsion system mounted on the stern of a boat adaptable to propelling the boat at high speeds through and over water. The depth of operation of the propeller in the water as well as the angle of attack or attitude of the propeller are each adjustable independently of the other, and steering is accomplished by lateral movement of the propeller in a single plane without modifying the depth and attitude of the propeller. In construction the drive shaft assembly is divided into three connected parts, namely the power drive shaft and an intermediated connecting shaft and the propeller shaft. The depth of operation of the propeller and its attitude are adjustable independently of each other by supporting the interconnected shaft assembly from a vertically adjustable overhanging beam structure extending from a vertical support rod at the stern of the boat about which the beam can be moved through an arc to steer the craft.

Description:
BACKGROUND OF THE INVENTION 
     This invention is a marine propeller drive system adaptable to propelling power boats through and over water at high speeds and efficiency, the system being particularly adaptable to propelling high speed planing boats such as catamarans. In propelling a boat forward at high speeds and efficiency it is desirable that its propeller be adjustable in its depth of operation below the water surface as well as with its axis of rotation set at an optimum angle for speed and efficiency. 
     PRIOR ART 
     One marine propulsion system representative of the prior art is one in which a propeller at the end of a long drive shaft is lifted or lowered about a pivot at the stern of the boat. The propeller is lifted up or lowered to change its depth but its angle of operation is correspondingly changed limitedly due to the length of the drive shaft. Such a system is disclosed in U.S. Pat. No. 5,791,954, Johnson, Jr., issued Aug. 11, 1998. Another prior art system of propulsion is one in which the propeller shaft is much shorter and the range of angular orientation of the propeller on its axis of rotation is greater but in orienting the propeller its depth of operation is limited by the orientation. Such a system is disclosed in U.S. Pat. No. 3,933,116, Adams, et. al., issued Jan. 20, 1976. In other words, at one side of the spectrum of systems the depth of operation of the propeller determines its angle of operation whereas on the other side of the spectrum the angle of operation determines the depth of operation. 
     BRIEF DESCRIPTION OF THE PRESENT INVENTION 
     According to the present invention, the propeller is a marine propulsion system driven by apparatus in which the propeller is adjustable in its depth of operation independently of its angle of operation. This is made possible by supporting the propeller and its propeller shaft and skeg support assembly adjustable about a pivot in an overhanging beam assembly and by providing an intermediate connecting shaft between the engine drive shaft and the propeller shaft. In addition, the level of the overhanging beam assembly with the supporting skeg assembly is vertically adjustable to establish the depth of operation of the propeller below the water level. The details of construction and operation of the assembly will become more apparent upon review of the description of the invention in relation to the drawings accompanying this specification. 
     A principal object of the present invention is to provide a boat propulsion system in which the angle of the axis of rotation of the propeller and the depth of operation of the propeller can be selected independently of each other and in which the entire assembly can be laterally adjustable to steer the boat. 
     Another object of the invention is to provide a system of propeller propulsion for a boat to be operated at high speed in which the propeller angle of rotation is adjustable for operation at an ultimate in efficiency. 
     Still another object of the invention is to provide a boat propulsion system in which the propeller can be operated at any of an infinite number of angles in a given angular range independently of its depth of operation. 
     Another important and allied objective of the invention is to provide a system in which the propeller operated at a selected angle of operation can be independently raised and lowered to establish an optimum depth of operation. 
     A principal feature of the invention compared to prior art stem drive systems for water craft is that it allows infinite adjustment of the propeller shaft height and angularity or attitude relative to the running plane of the boat, and additionally that such adjustments can be made while the boat is under way. 
     Other objects and structural features which are believed to be characteristic of the invention are set forth with particularity in the appended claims. My invention, however, both in organization and manner of construction, together with further objects and features thereof may be best understood by reference to the following description taken in connection with the accompanying drawings. 
     According to the present invention hereafter described in detail, the system&#39;s propeller can be selectively raised and lowered to fix its depth in the water and can be independently adjusted in its angle of orientation to establish an optimum set of propulsion conditions such as for speed and efficiency of operation. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an illustration of a prior art system for direct drive of a propeller with a long shaft in which the angle of the propeller is changed limitedly by lifting or lowering the propeller drive shaft about a pivot point at the stem of a boat; 
     FIG. 2 is an illustration of a prior art propeller drive system mounted at the stem of a boat in which the propeller angle is changed by moving the propeller and its drive shaft system in pendulum-like fashion about an upper pivot point at the stern of the boat. 
     FIG. 3 is a side elevational view of a propulsion system constructed according to the concept for the present invention in which the system is driven by an inboard engine (not shown) with the assembly extending stemwise of the boat illustrating the propeller being oriented slightly downwardly from horizontal; 
     FIG. 4 is a side elevational view corresponding to that of FIG. 3 in which the propeller is illustrated oriented in an upward direction; 
     FIG. 5 is view of the propulsion assembly of FIGS. 1 and 2 illustrated mainly in a cross section and broken away view to show the interassociation of parts which makes the novel functional aspects of the invention possible; and 
     FIG. 6 is a top plan view of the assembly of FIGS. 3-5 illustrating in solid and dashed lines how the propulsion assembly can be moved at a lateral angle from one side to the other to steer the boat on which it is mounted. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 illustrates a prior art stem drive propulsion system  10  which shows how a propeller  16  and its drive shaft  12  can be raised and lowered about a pivot point  13  to change the orientation of the propeller relative to the water surface and the boat bottom while a skeg  64  of the drive is maintained in the water. The range of angular change of the propeller in such instance is quite limited dependent upon the drive shaft orientation to fix both the depth of the propeller and to maintain the skeg  64  in the water for steering. 
     FIG. 2 illustrates another prior art stem drive system  15  in which the propeller  16  is driven by an articulated assembly of drive shafts  17   a ,  17   b , and  17   c.  The horizontal drive shaft  17   a  is connected to the propeller shaft  17   c  by a connecting shaft  17   b.  To trim the propeller  16 , or in other words, change its driving orientation, the assembly must be swung in pendulum fashion about the pivot point  18  which causes the propeller to be lifted or lowered in the water. When lifted too far, both the propeller and the skeg  19  can become exposed above water. In this arrangement the depth of the propeller and its orientation are also not adapted to being independently adjusted. 
     FIG. 3 in contrast is an illustration of the overall assembly of components incorporated in the presented propulsion system in which the propeller attitude is adjustable independently of its depth adjustment. The system is mounted on the stern  20  of the boat, shown in broke away view with its transom  21  and a drive shaft connection  22  illustrated in dotted lines. A power supply shaft (not shown) extends from the connection  22  to a joint housing  23  through which it connects to an intermediate connecting shaft  24  shown in greater detail hereinafter. The intermediate shaft  24  connects with the propeller shaft (not shown) which extends through the propeller shaft thrust housing  28  to drive the propeller  25  secured to the end of the propeller shaft by a lock-nut  26 . A skeg  29  provided to assist in steering the craft extends below the propeller shaft thrust housing  28 . The propeller shaft and its thrust housing  28  are supported by a shaft housing support  27  attached to a prop wash shield  31  which is pivotally mounted on a horizontally aligned pivot pin  33  which in turn is mounted on the housing of an over-beam assembly  30  mounted at the stem  20  in cantilevered relation over the interconnected shaft  24  and the propeller shaft trust housing  28 . The propeller shaft extending through the propeller thrust housing  28  and the propeller  25  are thus capable of being angularly trimmed by selectively lowering and raising the prop wash shield  31  about its pivot support pin  33 . The pivotal movement of the prop wash shield is effected by actuating and controlling an interiorly mounted piston having a piston rod  34  extending therefrom and connected to the prop wash shield  31 . 
     The steering of the boat is effected by moving the over-beam assembly  30  laterally about a vertically mounted pivot steering rod  50  (shown in dashed lines) enclosed in the housing secured to the transom  21  of the boat. The over-beam assembly  30  is laterally moveable in either direction about the steering rod  50  by a pair of identical pistons  36  and  36   a  (FIG. 6) swingably mounted on opposite sides of the over-beam assembly  30 . Each piston is mounted at a fixed vertical level on hinge pins  42  and  42   a,  which in turn are secured in a pair of spaced piston mounts  43  and  43   a,  above and below the end of each piston and arranged to permit the piston to move in an arc along side the over-beam assembly with which it is associated. The pistons  36  and  36   a  have associated piston rods  37  and  37   a  respectively extending to steering pins  39  and  39   a  respectively fixedly mounted between two spaced pin mounts  40  and  40   a  respectively in the upper region of the over-beam assembly and lower pin mount  41  both projecting from the side of the over-beam assembly. The piston rods  37  and  37   a  each have at their ends a connection  38  which is vertically slideable on the steering pin  39  so that as the over-beam assembly is moved up or down along the steering rod  50 , as hereinafter described, a corresponding lifting and lowering sliding adjustment of the piston rod  37  and its sliding connection  38  occurs on its steering pin  39 . This can be seen by reference to FIG. 4 wherein the over-beam assembly  30  has been lowered a bit in contract to its position shown in FIG.  3 . 
     As indicated, to steer the boat the over-beam assembly is moved to one side or the other about the steering rod  50 , for example, by extending a piston rod  37  on one side of the over-beam assembly and retracting the piston rod  37  on the opposite side of the over-beam assembly. Such steering movement is accomplished without changing the depth or angle of orientation of the propeller  25 . In other words the propeller can be swung in a horizontal plane through the water without changing its attitude or the orientation of its drive shaft. 
     FIG. 4, shows the over-beam assembly  30  lowered slightly relative to its showing in FIG. 3 and a change in orientation of the propeller  25  illustrated by showing the prop wash shield  31  drawn upwardly about its pivot pin  33  and having been drawn upwardly to its limit where its lift rod  34  no longer shows. This lifting causes both the propeller  25  and its propeller shaft interior of the prop thrust housing  28  also drawn upwardly to the limit of its angular range. 
     As the propeller is thus lifted in its angular orientation, the over-beam assembly can be correspondingly lowered to lower the propeller to a depth desired below the surface of the water. An infinite number of angles of orientation of the propeller and its propeller shaft can thus be selected within the range for which it is designed. Correspondingly, the depth to which it is to operate can be selected by lifting or lowering the over-beam assembly  30  to any of a number of depth settings within the range for which the system is designed. In both cases of adjustment, either for orientation of operation of the propeller or the depth of operation of the propeller the range of selection can be quite wide to attain the most effective settings for the propulsion system of the boat on which it is mounted. 
     FIG. 5 illustrates in cut away section both the interior of the over-beam assembly  30  and the assembly of the power supply drive shaft  64  extending from the connection  22  to a double universal joint assembly  65  within a sealed housing  66 . The intermediate shaft  24  is connected by way of the joint  65  to the power drive shaft  64  and its other end is connected to a single universal joint  75  joined within a joint housing  76  to the prop propeller shaft  74 . Rotational power is thus transmitted by way of the power drive shaft  64  through the universal joint  65  to the propeller shaft  74  and to the propeller  25  by way of the intermediate shaft  24 . The joint  65  is preferably one such as a double yoke universal joint which permits a wide lateral swing of the propeller shaft and intermediate shaft during steering upon lateral movement of the over-beam assembly  30 . The joint assembly  65  is mounted in alignment under the end of the steering rod  50 , in line with the axis of rotation of the rod  50  to provide the same axis of rotation for the lateral movement of the propeller shaft  74  as that of the over-beam  30  during steering of the water craft. 
     The universal joint  65  also provides a horizontal axis for rotation for the combination of the intermediate connecting shaft  24  and the propeller shaft  74 . In addition the universal joint  75  connected to the end of the intermediate shaft  24  and joining to the propeller shaft  74  provides a range of vertical angular movements of the propeller shaft  74  to set the axis of rotation of the propeller  25 . The angle is changed by drawing the piston rod  34  upwardly or pushing it downwardly from a piston  44  pivotally mounted at a support pin  45  on the over-beam. Correspondingly the end of the piston rod  34  is pivotally secured to the over-beam assembly  30  at a pivotal connecting pin  46  thereby allowing self adjustment of the piston  44  and the piston rod  34  as angular changes of the propeller and its propeller shaft  74  occur when angular settings of the propeller are made upon the propeller shield  31  being lifted and lowered by the piston  44  and piston rod  34  about the pivot pin  33 . 
     The over-beam assembly  30  is lifted and lowered selectively by a piston  56  and its piston rod  57  extending therefrom connected at a connecting pin  55  to which the end of the piston rod  57  is secured. The piston  56  is mounted at a fixed level by securement to a laterally moveable swivel fork  58  which has projections extending over and under an intermediate fixed mount  52  projecting from a stern mounting plate  54 . The swivel fork  58  is arranged to have the steering rod  50  extend therethrough to permit it to be swung with the over-beam assembly  30  as it is moved laterally during steering of the water craft. 
     The steering rod  50  is fixed in its vertical position between an upper fixed mount  51  and a lower fixed mount  53 , both projecting rearwardly from the stem mounting plate  54 . The over-beam assembly  30  is mounted on the steering rod  50  by way of an upper sliding bushing  60  and a lower sliding bushing  61  incorporated in the upper and lower walls of the over-beam assembly. The over-beam assembly is provided with internal bracing such as vertical bracings  47  and  48  representative of these and other bracings which can be provided to impart a rigidity to the assembly. Thus the over-beam assembly  30  can be moved up and down by the piston  56  fixedly secured to the intermediate mount  52  projecting from the stem mounting plate  54 . This results in a corresponding lifting and lowering of the propeller shaft housing  28  without changing the attitude of the rotation of the propeller  25 . To change the attitude or angle of the axis of rotation of the propeller  25 , the prop wash shield  31  is lifted or lowered about its pivot pin  33  which angular adjustment can be made independently of the lifting and lowering of the over-beam assembly. 
     The manner in which the boat can be steered is illustrated in FIG. 6 wherein the over-beam assembly is swung about the steering rod  50  under the force of the steering pistons  36  and  36   a  on opposite sides of the over-beam. The steering pistons  36  and  36   a  are mounted between piston mounts  43  and  43   a  and secured by hinge pins  42  and  42   a  respectively. Their respective piston rods  37  and  37   a  extend to fastening projections  40  and  40   a  projecting laterally from the over-beam assembly  30 . The piston rods  37  and  37   a  are secured to the projections  42  and  42   a  by hinge pins  39  and  39   a  respectively. The over-beam assembly is swung about the steering pin  39  under the force of the steering pins  36  and  36   a  by having the force of one steering piston rod causing the over-beam assembly to be pushed to one side of the boat transom while the steering piston rod on the other side of the boat is retracted within the piston. The hinge support at both ends of each piston and its respective rod allows each piston and rod assembly to be swung about its hinge pins at both ends of each piston and rod assembly. 
     FIG. 6 also illustrates how the over-beam assembly  30  can be swung both in the starboard and port directions to place propeller  25  in a position to steer the boat. The lift rod  34  extending from the piston  44  is positionable to raise and lower the propeller axis of rotation within its design range. The propeller shaft  74  is oriented with its housing  28  about the universal joint  75  by lifting of the propeller wash shield  31  about its pivot pin  33 . The universal joint  75  is located directly under the horizontal pivot pin  33  so the propeller shaft  28  moves through an angle about the joint  75  corresponding to that through which the propeller wash shield  31  moves about its pivot point  33 . 
     The double universal joint  65  located between the power drive shaft  64  and the intermediate connecting shaft  24  is located directly under and in alignment with the axis of the steering rod  50  which allows the axis of the propeller shaft  74  to be swung laterally over the angular range matched to the movement of the over-beam assembly  30 . The intermediate shaft  24  which in effect connects the drive shaft  64  and the propeller shaft  74 , because of its being connected between the double universal joint  65  and the second universal joint  75 , can accommodate the lateral movement of the propeller shaft  74  about the joint  65  as well as the vertical angular movement of the end of the propeller shaft  28  about the joint  75  and its overlying pivot pin  33  for the shield  31 . 
     The rotational power from the inboard motor is transmitted directly to the drive shaft  64  through its connection  22  and into the universal joint  65 , a ball and socket assembly. As indicated the joint  65  is in the form of an H-type double yoke universal assembly, such as a double Cardan universal joint, which allows a wider than usual range of angular movement of the over-beam assembly during steering. By way of example, the lateral angular movement of the over-beam and the underlying intermediate connecting shaft  24  about the universal joint  65  can be in the order of plus or minus 24 degrees. 
     The power for lifting and for lateral movement of the over-beam assembly can be supplied preferably by hydraulic means but alternately can be pneumatic or electrical. 
     This direct drive to propeller shaft design eliminates the need for gear sets with their corresponding power loss, thereby increasing reliability of the present system. The fact that the steering is done by turning the propeller laterally eliminates the need for a separate rudder for the boat which eliminates some loss by friction at high speeds. In practice not only one, but two of three of the described propulsion systems can be operated together in unison at the stern of a boat for speed as well as for steering of the craft. Also, with the lack of gearing, less maintenance is entailed in operating the system. 
     In view of the foregoing it will be understood that many variations of the arrangement of the invention can be provided within the broad scope of principles embodied therein. Thus, while a particular preferred embodiment of the invention has been shown and described, it is intended by the appended claims to cover all such modifications which fall within the true spirit and scope of the invention.