This invention relates to outboard drive units and, more particularly, to a drive unit for use with a watercraft, such as a pleasure boat.
Conventional marine outboard drive units are supported on a transom of a boat and can be tilted about a horizontal tilt axis. When required for storage, servicing or repair, the drive units are tilted upward to raise the units above the water surface. There is no intermediate tilting position during operation of a watercraft; conventional outboard motors are submerged during operation below the water surface.
The majority of outboard motors are equipped to run in the water. A special category of outboard motors is designed to run in muddy waterways, in shallow water and in the body of water that has overgrown with vegetation. In Such cases, the conventional outboard drive unit becomes almost useless, especially if vegetation wraps around the rotating portion of the propeller shaft or when the propeller shaft encounters particularly viscous or hard obstacles. There also exists a possibility of the propeller striking an underwater tree stump with a disastrous result.
The special category of mud propellers utilizes what is known as a “go-devil” —a special extended rod with a wide steering radius of up to 72 inches that helps raise the propeller out water or move it sideways in case of heavy obstructions. However, these types of drive units are difficult to operate and require special skill.
The present invention contemplates elimination of drawbacks associated with the prior art and provision of an outboard drive unit that can be tilted to extend partially above water and that would allow the watercraft to move safely in clear water as well as mud, while protecting the propeller unit.
It is, therefore, an object of the present invention to provide an outboard drive unit that can be used on a conventional watercraft, such as a pleasure boat, for operation in clean water as well as mud conditions.
It is another object of the present invention to provide an outboard drive unit that allows tilting of the propeller unit to partially raise the propeller blade above the water.
It is a further object of the present invention to provide an outboard drive unit with a propeller having high pitch as compared to conventional propeller units to facilitate trimming of the boat in muddy waters.
It is still a further object of the present invention to provide an outboard drive unit that has a small steering radius to facilitate control of the boat.
These and other objects of the present invention are achieved through a provision of an outboard drive unit for a watercraft that has an upper unit housing an engine, or motor and a lower unit carrying a propeller assembly. Interposed between the engine and the propeller assembly is an input shaft, which engages a gear assembly.
The gear assembly is also operationally connected to the propeller assembly; the gear assembly is a reduction gear assembly with a reduction ratio is in the order of 1.5:1, as compared to conventional mud motors having a 1:1 gear ratio. Tile reduction gear allows a propeller with a greater pitch to be rotated using the same torque value generated by the engine.
The outboard drive unit can be tilted to control the level of submerging of the propeller assembly in water or mud. Normally, the propeller assembly is submerged when the watercraft is stationary. During acceleration, especially in mud, the propeller encounters significant resistance from the liquid medium. By tilting the drive unit and partially elevating the propeller assembly above water, an operator can use a larger propeller with the same engine power. This design also allows to reduce the drag forces acting on the propeller, thereby increasing speed and efficiency.
The outboard drive unit of the instant invention has the propeller shaft oriented at an obtuse angle in relation to the input shaft. This design allows to avoid damage to the propeller when encountering grass or underwater tree stumps. The drive unit has a steering radius of less than 20″, more precisely about 16″, which is a significant improvement in maneuverability as compared to conventional “go devil” designs.
Reference will now be made to the drawings, wherein like parts are designated by like numerals, and wherein
Turning now to the drawings in more detail, numeral 10 designates the outboard drive unit of the present invention. The outboard motor 10 comprises an upper unit, or power head 12, a drive shaft housing 14 and a lower unit 16. The power head 12 includes an internal combustion engine (not shown) of a conventional design, for instance and inline two-cylinder motor that operates on a four-stroke combustion principle.
Similarly to conventional engines, the engine employed in the design of the present invention has reciprocating cylinders moving within combustion chambers and moving a crank shaft or drive shaft. The drive shaft transmits rotational force to the lower unit 16 through an input shaft 20.
The engine 12 is connected to a fuel supply system (not shown) that supplies a fuel charge to the combustion chambers to allowing damning of the fuel an exhaust of gases out of the combustion chambers. Although not shown, it is within the knowledge of those skilled in the art that the engine 12 is also connected to lubrication and cooling systems that are conventionally employed for operation of such type of motors.
The lower unit 16 comprises a support assembly 22, which supports the drive unit 10 on the watercraft transom 24. The support assembly 22 orients the lower unit along with the associated propeller assembly such that the propeller is submerged when the hull of the watercraft is stationary on a body of water.
Turning now in more detail to
Mounted between the attachment plates 30, 32 is an electric clutch 36 resting on a drive coupling 38. The plates 30 and 32, as well as the coupling 38 are provided with central through openings allowing extension of a drive shaft connection therethrough. The input shaft 20 is connected to the drive shaft of the engine 12 for transmitting rotational force to a propeller shaft 40.
The upper portion of the input shaft 20 is enclosed in a standoff tube 42 mounted below the lower attachment plate 32. An upper steering bearing 44 is interposed between the stand off tube 42 and the plate 32. A steering tube 46 houses the standoff tube 42. A lower steering bearing 48 abuts the bottom of the standoff tube 46. A pair of U-shaped brackets 50, 52 extend about the outer circumference of the steering tube 46 for engagement with the support assembly 22. The brackets 50, 52 can be secured with a pair of wing nuts (shown in
The support assembly 22 also comprises a swivel bracket 56 provided with a pair of levers 67 and a swivel bracket cross bar 68. An internally threaded opening is formed in the cross bar 68 for receiving a distant end of a steering shaft 58 therethrough. A pair of tilt pins 60 (only one is shown in
The support bracket 62 is fitted between the levers 67 and receives the tilt pins 60. The clamp 64 is secured between the arms of the support bracket 62 and is attached to the support bracket cross bar 66, as can be better seen in
Secured below the lower steering bearing 48 is an upper thrust bearing 72 that is fitted, with a jam nut 74, a spacer 76 and an upper seal 78, into an input housing 80. The input housing 80 also houses a distant end of the input shaft 20. An annular flange 82 formed in the lower portion of the input housing 80 engages with a lower steering bearing 48 when the lower unit 16 is assembled.
Mounted below the upper thrust bearing 72 is an output thrust bearing 84, which is mounted, together with an input gear 86 in a hub 90. The input gear 86 is sized and shaped to mesh with an output gear 92 and provide a gear reduction in the ratio of 1.5:1 between the input shaft 20 and the propeller shaft 40. A bearings cartridge 94 houses a proximate end of the propeller shaft 40 along with a forward thrust bearing 96 and a rear thrust bearing 98. An internal seal, such as an O-ring 100 may be seated around the propeller shaft 40 at the point of engagement with the rear thrust bearing 98.
A distant end of the propeller shaft 40 is secured in a stuffing tube 102 that carries a skeg 132 and a cavitation plate 130. The cavitation plate 130 is oriented at about a right angle in relation to the skeg 132. A propeller 120 is secured for rotation on the propeller shaft 40 and an end cap 134 is fitted on the distant end of the propeller shaft 40. The design of the propeller assembly may also include a needle roller bearing 136 mounted between the end cap 134 and the stuffing tube 102. A pair of lower seals 138 protects the needle roller bearing 136 during rotation of the shaft 40.
The design of the propeller 120 can be better seen in
Turning now to the mode of operation of the drive unit of the present invention, with reference to
When the propeller shaft 40 along with the propeller 120 is oriented to extend below the bottom of the watercraft 140, there is a possibility of grass and other vegetation getting caught on the lower unit and cause cooling water suction that may plug and block water in the propeller. Underwater stumps present additional danger. The impact directly with the front of the lower unit causes the motor to “kick up” very hard. The traditional “go-devil” unit operating in muddy conditions is imperfect as it causes the propeller to pop out of water every time the propeller encounters mud or grass. The pivot point allows the propeller shaft to be raised while the cavitation plate remains under water in such a design. However, the shaft of the propeller tends to be pushed above the pivot point, rendering propulsion of the boat very difficult.
The design of the present invention utilizing the obtuse angle orientation between the axis of the propeller shaft and the input shaft minimizes or altogether eliminates this problem. The direction of the thrust force designated by numeral 150 keeps the propeller below the pivot point 152 both when the boat is stationary (
The drive unit 10 turns about the pivot point 152 by the boatman turning the wheel 70 of the attachment unit 22. The operator can easily change the relative orientation of the steering shaft by turning the wheel 70 clockwise or counter-clockwise. By turning the wheel 70, the operator causes the drive unit to change its relative position to the surface 144, helping the unit to move through water or mud.
With the propeller partially out of the water, a larger propeller can be turned with the same engine having a pre-determined power capacity. This also means less drag in the water since a smaller portion of the lower unit is submerged. As a result the same power motor can achieve more speed and efficiency using the lower unit of the design of the present invention.
The present invention is particularly advantageous when the boat needs to accelerate in shallow, muddy water full of vegetation, grass, etc. Position of the propeller in such cases can be seen in
During trim/tilt of the watercraft, the hand wheel 70 pulls on a thrust bearing. The threaded steering rod, or shaft 58 pulls the cross bar 68 moving the trim lever assembly with the levers 67. The trim levers 67 pivot on the pin 60 and tilt the drive unit 10. As the motor tilts, the propeller 120 is lifted.
Many modification and changes can be made in the design of the present invention without departing from the spirit thereof. I, therefore, pray that my rights to the present invention be limited only by the scope of the appended claims.
This application is a continuation of my co-pending application Ser. No. 11/156,184 filed on Jun. 20, 2005, which is a continuation of application Ser. No. 10/389,157 filed on Mar. 14, 2003, entitled “Outboard Motor,” now U.S. Pat. No. 6,921,305, the full disclosures of which are incorporated by reference herein and priority of which is hereby claimed.
Number | Date | Country | |
---|---|---|---|
Parent | 11156184 | Jun 2005 | US |
Child | 11698003 | Jan 2007 | US |
Parent | 10389157 | Mar 2003 | US |
Child | 11156184 | Jun 2005 | US |