Lightweight outboard electric motor system

An outboard electric motor kit that includes an electric motor assembly with a unitized propeller hub, a transom mount, a rechargeable electric battery, and an optional recharger. The assembly includes an electric motor unit located in an upper housing. A lower tube stem is attached and that extends downward from the upper housing to a lower housing. Formed on the lower housing is a receiving cavity with a rearward facing propeller hub opening. A drive shaft coupled to the motor unit extends downward inside the lower tube stem and mounted to a gear support block located in the receiving cavity. Mounted on the end of the drive shaft is a main gear. Mounted on the gear support block is a fixed axle that extends coaxially aligned through the propeller hub opening. Extended through the opening and coaxially mounted over the fixed axle is a removable propeller hub assembly.

COPYRIGHT NOTICE

Notice is hereby given that the following patent document contains original material which is subject to copyright protection. The copyright owner has no objection to the facsimile or digital download reproduction of all or part of the patent document, but otherwise reserves all copyrights whatsoever.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to outboard electric motors for boats, and more particularly to such outboard electric motors that are lightweight, portable and require little or no maintenance.

2. Description of the Related Art

Operators of oar driven small boats, such as dinghies, canoes, kayaks and inflatable watercraft, find it sometimes desirable to propel their boats using an electric motor. Ideally, the electric motors and their batteries should be sufficiently lightweight to they may manually carried and adaptable or attachment to different transoms or transom bars.

Typical outboard electric motors on small boats consist of direct drive motor units mounted inside a submerged housing. Such outboard electric motors use relatively small propellers that measures 5 to 11 inches in diameter. While such propellers are relatively small and inefficient at speeds under 10 mph, the higher RPM and torque requirements of large propellers make them unsuitable for direct drive electric motors. In addition, because the drive motor units are submerged, leaks around the housing is a failure point.

There are two types of gear systems used with outboard electric motors—sealed gear systems in which the gears and bearings lubricated with grease are used to rotate a propeller are all located in a watertight, sealed housing; and non-sealed gear systems in which the gears and bearings are located in a non-watertight housing in which water flows and in direct contact with the gears and bearings and acts as a lubricant.

One drawback with watertight, sealed gear systems is that the gears and bearings must periodically cleaned and re-greased. Another drawback is that the watertight, sealed system is that the watertight housing can fail allowing water or moisture to enter and damage the gears and bearings.

One drawback with non-watertight gear systems is that water has lower lubricating properties than grease making the gears and bearings vulnerable to greater wear and corrosion. As a result, the gears and bearings used in non-watertight gear systems must be replaced more often which heretofore has been more expensive and time consuming than lubricating the gears and bearings in watertight, sealed systems.

Many small boats with electric motors are operated in small bodies of water that are shallow and require the small boat to be run aground on the beach to load and unload. As a result, the motor's lower shaft and propeller often contact submerged objects or the ground. To prevent damage to the lower shaft or propeller, the mounting system used to mount the electric motor must either allow the user to selectively swing the electric motor out of the water or allow the lower shaft to freely swing upward when impacting submerged objects.

Some small boats, such as dinghies and kayaks, have built in transoms upon which an electric motor can be mounted. Some small boats, such as canoes, do not have transoms and therefore require a secondary transom plate adaptor mounted on the side of the boat upon which an electric motor can be mounted. Because the angle of the transoms or the transom plates can vary, the transom mount used with outboard electric motors must be adjustable for different transom angles.

U.S. Coast Guard regulations require that batteries used with outboard electric motors be securely attached at a fixed location inside the boat. Heretofore, secondary straps and buckles have been used to attach the batteries directly to a boat surface. Unfortunately, not all small boats have battery straps or buckles or surfaces for affixing a battery. In addition to holding the battery in a fixed location inside the boat, attaching the batteries to the boat is especially important because small boats can easily overturn in the water causing all non-buoyant objects, such as an electric batteries to be lost.

SUMMARY OF THE INVENTION

In summary, the invention is an outboard electric motor kit that includes a lightweight, portable electric motor assembly designed to be used with small boats and lightweight rechargeable battery to supply electric current to the electric motor. The electric motor assembly includes upper housing that extends above the boat's transom or temporary transom plate. Located inside the upper housing is an electric motor unit. Attached to and extending down from the upper housing is a lower stem shaft. Connected or formed on the lower end of the lower stem shaft is a lower housing.

A key aspect of the invention is the discovery that the use of relatively inexpensive, replaceable gears in non-watertight housings that uses water as a lubricate is preferable over watertight housings found in the prior art that use more expensive gears and must be lubricated with grease.

To implement this discovery, the lower housing includes a receiving cavity with a rearward facing propeller hub opening. A drive shaft coupled at one end to the motor extends downward through the lower tube and into the lower housing's receiving cavity. The lower end of the drive shaft is held in the receiving cavity by a gear support block which is fixed in a stationary position inside the receiving cavity. Mounted on the section of the drive shaft above the gear support block and positioned within the receiving cavity is a main gear. Attached to the gear box and extending rearward from the receiving cavity is a fixed axle that is perpendicularly aligned with the drive shaft. The fixed axle extends rearward through the propeller hub opening on which a removable propeller hub assembly is mounted. The propeller hub assembly includes a secondary gear located therein and configured with teeth that are compatible and mesh with teeth on a main gear when the propeller hub assembly coaxially aligned over the fixed axle and inserted into the propeller hub opening and into the receiving cavity.

The propeller hub assembly and secondary gear are made of durable, lightweight inexpensive materials thereby making it more cost effective than watertight seal systems that typically use metallic gears and grease. During operation, water is able to flow into the receiving cavity and act as a lubricant. When servicing is needed, the entire propeller hub assembly may be easily removed from the fixed axle and replaced if necessary. If the main gear is damaged or worn, it too can be easily accessed and removed from the lower unit.

Mounted on the upper housing is a tiller arm that the user used to rotate and lift the electric motor assembly in the water. Mounted on the end of the tiller arm is a handle with an adjustable switch located therein that is electrically configured with the electric motor that enables the user to control the direction of the propeller's rotation and the rotation speed of the propeller. Also, mounted on the handle on the tiller arm is locking key slot that receives a locking key attached to a wrist band that activates the electric motor when inserted into the key slot and deactivates the electric motor when it is removed.

The outboard motor assembly may also include an adjustable transom mount that enables the electric motor assembly to be selectively attached to different transoms. The transom mount also enables the electric motor assembly to rotate freely side-to-side over its longitudinal axis. The transom mount also allows the entire electric motor assembly to rotated forward over the transom thereby lifting the lower shaft and lower housing out of the water.

More specifically, the transom mount includes two parallel side plates that are independently clamped to the transom and pivotally connected via an upper main bolt and a block member. The block member includes at least one longitudinally aligned pin that extends from each end of the block member and slides over a diagonally aligned ratchet slot formed on each side plate. Each ratchet slot includes a plurality of downward oriented pin slots that are longitudinally aligned in an offset angle to the line that extends from the forward edge of the ratchet slot opposite a pin slot to the longitudinal axis of the main bolt. In one embodiment, the block member is a rotating structure with two opposite spacer blocks and an intermediate narrow neck designed to roll over the front surface of a guide collar that connects to the motor's lower drive stem. During use, the upper housing must be manually lifted so that the pin may move from one set of slot pins to another set of slot pins on the ratchet slot to re-adjust the angle of the motor on the transom.

The electric motor assembly is distributed with a fast, rechargeable electric battery. The electric battery is watertight and includes means that enable the battery and the bag to float if accidentally dropped in the water. A locking pin is provided that enables the user to securely attaches the battery bag directly to the transom mount. An optional fast battery charger is also included in the kit.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Referring to the accompanying Figs. there is shown an outboard electric motor assembly generally indicated by the reference number8. The electric motor assembly8includes an electric motor12located in an upper housing10. Attach and extending downward from the upper housing is a lower stem tube18. Attached or integrally formed on the lower end of the lower stem tube18is a lower housing unit20.

As shown inFIGS. 2 and 3, formed on the lower housing unit20is a receiving cavity24with a rearward facing circular opening26. A drive shaft30is coupled at one end to the electric motor and extends downward through the lower stem tube18and into the receiving cavity24. Located inside the receiving cavity24is a gear support block34. The gear support block34is fixed inside the receiving cavity24and includes an upper bore36with a bearing38located therein. The distal end of the drive shaft30is connected to the bearing38thereby enabling it to rotate freely over the top surface of the gear support block34. Screws54extend through the sides of the lower housing unit20or through the rear surface of the gear support block34and into the inside surface of the receiving cavity24to hold the gear support block34in place therein. It should be understood that the gear support block34may be secured any suitable connectors.

Attached to the section of the drive shaft30located above the gear support box34is a main gear40with a plurality of teeth42designed to mesh with teeth67formed on the secondary gear66coupled to the propeller.

The receiving cavity24includes a rearward propeller hub opening26. Attached to the rear surface35of the gear support block34and extending rearward through the hub opening26is a coaxially aligned fixed axle50. The fixed axle50is attached to the rear surface of the gear support block34and is perpendicular to the drive shaft30. In different embodiments, the distal end of the fixed axle50includes a cotter pin hole55or threaded neck56. Coaxially aligned over the fixed drive shaft50and against the outside surface of the gear support block34is a flat washer53.

Coaxially aligned and extending into the hub opening26is a removable propeller hub assembly60which mounts on the fixed axle50. The propeller hub assembly60includes a propeller hub62designed to partially fit into the circular opening26, a replaceable secondary gear66, a propeller70and a removable cap75. The propeller hub62is a half-spherical structure with a circular cross-section that enables it to fit snuggly inside the hub opening26formed on the lower housing unit20.

As shown inFIGS. 2 and 7, a felt ring85may be attached to the inside surface of the circular opening26which acts as a filter to prevent these more damaging materials from entering the recessed cavity24when the propeller hub62is inserted into the circular opening26.

As stated above, the fixed axle50is stationary and acts as a combination mounting and aligning structure for the propeller hub62and the secondary gear66. In the embodiments shown inFIG. 9, the propeller hub62includes internal bearings64that coaxially align the propeller hub62over the fixed axle50. Disposed on the inside surface of the propeller hub62is a secondary gear66that includes a longitudinally aligned neck68that fits into a counter-bore63formed on the inside surface of the propeller hub62. The counter-bore63and neck68are ‘keyed’ and have compatible shapes so that the propeller hub60and the secondary gear66are interconnected and are rotatably locked together. Alternatively, it should be understood that the secondary gear66and the propeller hub62may be a single structure with the secondary gear66adhesively attached or integrally formed on the inside surface of the propeller hub62. With all the embodiments, removal and replacement of the propeller hub62and the secondary gear66may be done simultaneously.

In the embodiment show inFIG. 2, the propeller hub62is secured to the fixed axle50by a cotter pin95that extends through a bearing cap75and a hole52formed on the distal end of the fixed axle50. In another embodiment shown inFIG. 6, the fixed axle50is replaced by a second fixed axle50′ with a threaded neck56that connects and a threaded nut90. InFIG. 7, a shoulder screw86is used in place of the first and second axles50,50′ and the cap75and nut90. When a shoulder screw86is used, a modified gear block34′ is used with a threaded bore35that attached to the shoulder screw86.

In one embodiment, the main gear40is made of more durable material than the secondary gear66causing the replaceable secondary gear66to preferentially wear or fail sooner than the main gear40. In this embodiment, the main gear40is of stainless steel and approximately 1 inch in diameter, the fixed axle50or50′ is also of stainless steel and 5/16 inch in diameter. The bearing34for the main shaft50is PEEK and held within a removable gear block52that measured approximately 0.75″ wide by 1.5 inches deep and 1 inch high. The gear block52is secured using ¼-20 stainless steel screws through the lower housing unit20. As shown inFIG. 3, the fixed axle50,50′ has a ⅛ inch crosswise hole through its end through which a ⅛ inch diameter×1 inch cotter pin95is pressed in conjunction with a 1 inch diameter bearing cap75. The propeller70is made up of a 13.5 inch in diameter and made up of glass-filled nylon and the propeller hub62is approximately 2 inches in length and 1.5 inches in diameter. The secondary drive gear66is approximately 1 inch in length and 1.5 inches in diameter. The propeller assembly60is designed to be replaced in two minutes and the gear block34can be replaced in 5 minutes. Both can be accomplished using a screwdriver and pliers.

The electric motor assembly includes an adjustable transom mount100used to reduce the amount of stress exerted on the mounts' main bolt110to reduce breakage or bending thereof and to prevent rotation of the motor8on the transom6when the motor8is reversed (seeFIG. 10).

The adjustable transom mount100includes two parallel side plates102,102' pivotally connected via an upper main bolt110and a lower block member140,150. Each side plate102,102' includes a forward extending arm104with a screw clamp106attached to its distal end. Also formed on each side plate102,102' is a curved, diagonally aligned ratchet slot130. The two slide plates102,102' are aligned in a parallel configuration and spaced apart and connected together by the main bolt110.

Extending around the motor's lower tube18is a cylindrical shaped guide collar114. Formed on the guide collar114is a forward extending arm116with a bore118through which the main bolt110extends.

Located below the main bolt110and transversely aligned between the two side plates102is a block member140,150includes at least one longitudinally aligned pin136,138, or144,146, respectively, that slides over the diagonally aligned ratchet slot130formed on each side plate102,102'. In one embodiment shown inFIGS. 11-13, the block member is a rotating with two opposite spacer blocks132,134and an intermediate narrow neck133that rolls over the front surface of the motor's guide collar114. In another embodiment shown inFIG. 14, the block member140is a rectangular fixed block with two pins144,146that extend longitudinally from the block's opposite ends. The two pins136,138or144,146extend into the pin slots132formed on the ratchet slot130. Attached to the rear surface of the fixed block member140is a U-shaped collar150that snaps onto the motor's guide collar114to securely hold the motor guide collar114and prevent its rearward rotation when the motor8is reversed.

As shown more clearly inFIG. 15, each ratchet slot130includes a plurality of downward oriented pin slots132that are longitudinally aligned in an offset angle to a line136that extends from the forward edge134of the ratchet slot130opposite a pin slot132to the longitudinal axis111of the main bolt110.

FIG. 16is a sectional side elevational view of the upper housing10and a 24 volt electric motor202located therein. The electric motor202includes drive shaft stem204that is longitudinally aligned inside the stem tube. Mounted around the drive shaft stem204is a shaft coupler208. Attached to the lower end of the shaft coupler208is the upper end of the main drive shaft. The electric motor202is mounted on a flat support plate212located inside the upper housing10. Bolts220,222, extend through a mounting collar218located below the flat support plate212and connect to the bottom surface of the electric motor202. The upper housing10includes a decorative top cowling230, two side cowlings232(only one shown) a front cowling234and a rear cowling236. Mounted inside the upper housing10and adjacent to the motor unit202is a printed circuit board (hereinafter called a PCB240) with a heat sink245. The PCB240is electrically connected to the motor unit202to the throttle switch and key switch in the handle discussed further below. The PCB240is also connected to a battery plug connector250.

FIG. 17is a sectional side elevational view of the handle310attached to the distal end of the tiller arm300with a rotating throttle knob320mounted on the end of the handle310. Formed on the end of the knob320is a longitudinally aligned key slot324designed to receive a compatible shaped magnetic key340. The key340includes a magnet344that is magnetically attracted to a reed switch312located in the handle310. The key340is attached to a lanyard346and lanyard clamp348to attached the key to the tiller arm300. Also attached to the lanyard346is an optional dead main lanyard350. Also located in the handle310is a linear hall effect sensor355.

FIG. 18is a perspective view of the electric motor assembly8being distributed as a kit400with a buoyancy battery case500containing the 24 volt rechargeable battery550, a standard 110 volt AC to 24 volt D.C. battery charger600, a battery case transom mounting pin525, two magnetic keys340attached to lanyards, a dead man lanyard350, and an electric motor assembly carrying case420.

FIG. 19is a perspective view of the rechargeable 24 volt battery505with a connection line530attached thereto with a water-proof connector50connected at one end designed to connect to the plug connector on the side of the outer housing. The battery505is stored inside a water-proof bag500that contains several foam layers540that provide buoyancy n in the event the bag540is dropped in the water or thrown overboard. The bag540also includes a transom mount loop560through which a transom mount pin525is inserted to attach the bag500to the transom mount.

There are three functions in the handle of the tiller arm. The first function is the enable switch that is activated with a key. The key man also be coupled to a lanyard and act as a dead man switch. In the embodiment shown in the Figs. the key330magnetically acts on a reed switch312(or hall-effect switch) in the tip of the handle310as shown in theFIG. 17. The enable switch includes an o-ring seal370that prevents water intrusion. Sealing can be by the handle enclosure alone or it can also be potted for sealing. It should be understood that the key330could also be of a mechanical switch however magnetic operation is better suited to a marine environment as it is completely sealed against water. Also, in the embodiment shown inFIG. 17, and stated above, the key330is attached to a short loop lanyard346which is connected to the handle forming a loop into-which another loop of cord350can be threaded. This cord350can be attached to the operator so that in the event of a capsize, the cord loop pulls free the key from it's switch position thereby turning off the motor for safety. An important unique aspect of the location of the enable switch is in the handle310and within easy reach.

The second function of the handle310is that the throttle control is conveniently located for easy access. The throttle control is located on the outer surface of the handle310thereby leaving the inside portion of the handle free for steering and for raising and lowering the motor assembly without accidentally changing the throttle setting. The arrangement shown inFIG. 17is also unique because it forms a linear hall-effect sensor that is acted upon by a magnet molded into the handle310. The benefit of this arrangement is that the wires30leading from the handle310to the motor unit can be separated using electrical connectors so that an extension can be inserted for remote powering, thus making the motor easily re-configurable for various installations by the user.

A third function is the raising and lowering of the stem tube and the lower housing. Raising and lowering an outboard motor is traditionally accomplished by reaching to the rear of the upper housing, grasping the back or a handle component formed or attached to the motor housing and then pulling the entire motor assembly upward. Lowering the prior art entire assembly is accomplished by pushing on the motor housing, usually in accordance with releasing a latch also positioned far aft. On a small boats, this requires un-natural leaning and may upset the balance of the boat. The present invention dispenses with this approach by providing two enabling means. The first is to secure the motor in the down position and up position by means of a friction device that requires no manual latching or un-latching. The second is to provide a geometrical pivot point that enables the motor to be tilted by pulling on the tiller arm300and to be lowered by pushing on the tiller arm300. The critical aspect of this means is that the distance from the motor pivot point to the pivot point of the tiller arm is between 4 and 7 inches, (5 inches being preferred), and that the angle from vertical of the motor pivot point to the pivot of the mount is approximately 45 degrees but may be as low as 30 degrees or as large as 60 degrees. When raised, the angle is reversed making the total change in angle to be approximately 90 degrees but it could be as much as 105 degrees or as little as 75 degrees.

The distance from the motor pivot point to the pivot point of the handle310is between 4 and 7 inches, with 5 inches being preferred. The desired distance is a function of weight of the motor being pivoted, a larger distance being required for heavier motors and a lower distance being necessary for lighter motors. Finally, the distribution of weight within the motor arrangement plays a role in this center-to center distance; When the motor is weighted more in the upper housing than the lower housing, the distance is reduced and when the motor is weighted in the lower unit, as is the case with pod-positioned electric motors, this center-to-center distance is increased to handle the extra torque needed in raising the motor.

In compliance with the statute, the invention described herein has been described in language more or less specific as to structural features. It should be understood however, that the invention is not limited to the specific features shown, since the means and construction shown is comprised only of the preferred embodiments for putting the invention into effect. The invention is therefore claimed in any of its forms or modifications within the legitimate and valid scope of the amended claims, appropriately interpreted in accordance with the doctrine of equivalents.