Patent Application
20230286630
The present invention relates to a device for an outboard motor, and more particularly, the present invention relates to a device with a controllable pitch propeller for outboard motors.
Existing Outboard Motors are generally based on a constant pitch propeller. The constant pitch propellers have their pitch fixed and remains fixed throughout their operation from 0 RPM to Max RPM. Constant pitch propellers are designed to work efficiently at a set RPM and this efficiency drops significantly at another RPM due to the fixed pitch. Also, the efficiency drops when the vessel moves. The torque output curve is typically non-linear when plotted against RPM and power output. The propeller torque requirement on the other hand is close to linear. So, constant pitch propellers generally have a mismatch of the output torque and the torque required by the propeller. This means at some instances, more torque is available than the propeller needs and in other instances, particularly at high RPM, less torque is available than what the propeller needs at that RPM, so the output engine has to compensate for that using more throttle input and more fuel.
Many attempts have been made in the art for incorporating a variable pitch propeller on an outboard motor. However, such attempts have failed because modifying the lower end of the outboard to house the pitch control mechanism is almost impossible due to size constraints and an increase in drag. The attempts have failed to put the pitch control mechanism in a small space of the hub of the propeller.
A need is therefore appreciated for an improved design of a variable pitch controller that is devoid of the above drawbacks of the fixed pitch controller.
The following presents a simplified summary of one or more embodiments of the present invention to provide a basic understanding of such embodiments. This summary is not an extensive overview of all contemplated embodiments and is intended to neither identify critical elements of all embodiments nor delineate the scope of any or all embodiments. Its sole purpose is to present some concepts of one or more embodiments in a simplified form as a prelude to the more detailed description that is presented later.
The principal object of the present invention is therefore directed to a controllable pitch propeller for outboard motors.
It is another object of the present invention that the propeller pitch is adjustable over a wide range of 0 to +90 degrees and 0 to −90 degrees.
It is still another object of the present invention that the propeller can provide forward thrust or backward thrust depending on the user setting of the pitch without changing outboard gear from forward to reverse.
It is a further object of the present invention that the pitch control mechanism can be installed in the hub of the propeller without any significant increase in the diameter or length of the hub.
It is a further object of the present invention that the propeller hub can be of a standard diameter.
It is still a further object of the present invention that the device can provide reverse thrust when required without changing gear or slowing down.
It is yet a further object of the present invention that the propeller provides more thrust at a given Engine RPM.
In one aspect, disclosed is an outboard motor with a controllable pitch propeller. The Device includes a novel mechanism for mounting a controllable pitch propeller. The pitch control mechanism can be installed in the hub of the propeller without any significant increase in the diameter or length of the hub.
The accompanying figures, which are incorporated herein, form part of the specification and illustrate embodiments of the present invention. Together with the description, the figures further explain the principles of the present invention and to enable a person skilled in the relevant arts to make and use the invention.
Subject matter will now be described more fully hereinafter. Subject matter may, however, be embodied in a variety of different forms and, therefore, covered or claimed subject matter is intended to be construed as not being limited to any exemplary embodiments set forth herein; exemplary embodiments are provided merely to be illustrative. Likewise, a reasonably broad scope for claimed or covered subject matter is intended. Among other things, for example, the subject matter may be embodied as apparatus and methods of use thereof. The following detailed description is, therefore, not intended to be taken in a limiting sense.
The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments. Likewise, the term “embodiments of the present invention” does not require that all embodiments of the invention include the discussed feature, advantage, or mode of operation.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting to embodiments of the invention. As used herein, the singular forms “a”, “an”, and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises”, “comprising,”, “includes” and/or “including”, when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
The following detailed description includes the best currently contemplated mode or modes of carrying out exemplary embodiments of the invention. The description is not to be taken in a limiting sense but is made merely to illustrate the general principles of the invention since the scope of the invention will be best defined by the allowed claims of any resulting patent.
The following detailed description is described with reference to the drawings, wherein reference numerals are used to refer to like elements throughout. In the following description, for purposes of explanation, specific details may be set forth in order to provide a thorough understanding of the subject innovation. It may be evident, however, that the claimed subject matter may be practiced without these specific details. In other instances, well-known structures and apparatus are shown in block diagram form to facilitate describing the subject innovation. Moreover, the drawings may not be to scale.
Disclosed is a device with a variable pitch propeller for an outboard motor. In one implementation, the disclosed device includes a variable pitch propeller, a pitch control mechanism, and a mounting member. Also, disclosed is an outboard motor with the disclosed controllable pitch propeller. The pitch control mechanism can be installed in the hub of the propeller without significantly changing the dimensions of the hub, which is the chief advantage of the disclosed invention. The disclosed pitch control mechanism and the propeller hub can be installed in standard outboard motors without significant modifications, making the disclosed invention versatile.
Referring to
The device 100 can include a servo-based linear actuator assembly, one or more variable pitch propellers, and a digital propeller pitch controller.
The controller, in one implementation, can be a microcontroller, such as an Atmega328 microcontroller. The controller can monitor the one or more parameters of the vessel, such as engine RPM and speed and can compute the optimum pitch for the propeller for better efficiency, higher thrust, and acceleration. The Engine torque vs RPM values can be stored, for example, on the ATmega EPROM. The controller can be operably connected to the servo liner actuator.
Referring to
In operation, the servo motor can rotate the acme screw and the rotary motion of the acme screw is converted to linear motion of the nut. The nut is connected to a push-pull rod. The push-pull rod can be connected to the propeller through a shaft 138. A control rod stabilizer 114 can extend from the actuator frame and can stabilize the shaft of the push-pull rod. The shaft can be connected to the plunger of the propeller. Moving the plunger in and out of the propeller hub can adjust the propeller pitch.
The variable pitch propeller can include a hub shell 108, the plunger 140, a spline core 112, and blades 107. The hub shell is cylindrical stainless-steel housing inside which the plunger and spline core are housed. The blades extend radially outwards from the outer surface of the hub shell, wherein the hub shell has holes for plunger base to which can be installed the blades. The plunger can slide within the propeller hub for modifying the orientation of the blades i.e., the pitch. The plunger can have grooves for the blade's lower end. As the plunger slides in or out of the hub shell, the pitch of the blade changes. The whole mechanism can be referred to as a slider crank mechanism, wherein the sliding motion of the plunger can be converted to the rotary motion of the blades.
The variable pitch propeller can be connected to an outboard output shaft. The spline core has splines to mesh with the outboard output shaft and provide a torque transfer mechanism from the shaft to the propeller.
The propeller blade has two main parts i.e., a hydrofoil and a circular root.
The drawings show the variable pitch propeller having four blades; however, the number of blades can vary without departing from the scope of the present invention. Function of the propeller blade is known i.e., to provide thrust force when spun around its axis. The profile of the blade can vary and any shape and size of the blade including diameter of the propeller is within the scope of the present invention.
The variable pitch propeller further includes a propeller hub, also referred to herein as hub shell.
The variable pitch propeller further includes propeller bases mounted to the propeller hub. The propeller blades are installed into the propeller bases. The number of propeller blades corresponds to the number of propeller blades. Thus, four propeller bases can be provided for four propeller blades.
On the bottom side of the propeller base can be a Cam follower 840. The propeller base can convert the linear motion of the servo linear actuator assembly into a rotary motion of the propeller blade resulting in change in the pitch. The propeller base can be made of high strength stainless steel alloy or similar material. The propeller blades can be mounted to the propeller base, wherein the locking key secures the propeller blade to the propeller base and prevents the blade from rotating relative to the propeller base. The locking bolt passing through the circular root can stop the propeller from separating. The propeller base can fit inside the propeller hub and together they can rotate around an axis of the propeller base, also referred to herein as axis of rotation.
The disclosed device further includes a plunger,
As shown in
The spline Core fits inside the propeller hub and has splines that mesh with splines on the outboard propeller shaft during installation. The purpose of the spline Core is to allow the propeller to be locked to the outboard propeller shaft and be rotated at low to max rpm. The spline core 112 also has slots 110 for exhaust gases from the outboard engine to vent out at the back of the propeller without interruption and thus create additional thrust. The spline core is fixed to the propeller hub with screws.
The push pull shaft can essentially be made from aluminum and has a rod shape profile. However, any other material for the push pull rod is within the scope of the present invention. The push pull shaft has female threads at one end that meshes with the male threads on the acme screw. The servo motor rotates the Acme screw in the push pull shaft. Due to the meshing threads, the rotary motion is transformed into linear motion of the push pull shaft. The servo motor may have a high-resolution rotary encoder that can keep precise angular position.
The actuator may further include an actuator seal housing that includes silicone seals that allow for linear motion of the push pull shaft but stops water from getting inside that may damage the servo motor.
Referring to
The mounting member 102, also referred to herein as a pusher shaft support, may be a Stainless-steel rod or similar structure that is of a hydrodynamic design for low drag and connects the actuator to the outboard using bolts. It is understood that the mounting member can be made from any other material and any variations in the design of mounting member is within the scope of the present invention.
As shown in
It is to be noted that the controller can compute and adjust the positive pitch of the propeller as well as negative pitch. In case, the user sets the electronic gear shifter to forward, the controller sets the pitch of the propeller to as positive value and hence the boat moves forward. But if the user sets the electronic gear shifter to reverse, the controller sets the pitch of the propeller to a negative value and hence the boat can brake very effectively because of reverse thrust and can also move backwards. This is advantageous that allows for thrust reversal without changing the gear to reverse on the outboard itself. Moreover, the in-built reverse gear mechanism in the outboard motor can be omitted while the disclosed device can cause the boat to move backwards and also brake efficiently.
In certain implementations, the controller can be an 8-bit microcontroller with set of instructions to determine optimum blade angle based on a variety of inputs for better fuel efficiency, acceleration, and thrust reversal/braking. The controller can process instructions in fraction of a second providing between control over the boat. For example, it may take the controller less than 2 ms to compute a solution for optimum blade angle and instruct the servo to change the blade angle and keep the blade angle locked until further instruction. The controller includes suitable processing circuitry and a memory for storing the set of instructions.
In certain implementations, the disclosed device may also include collision avoidance features which may take inputs from different proximity sensors on the hull of the boat placed in strategic locations. In the event of a potential collision, the disclosed controller can set the pitch to zero degree for zero net thrust. It is understood that instead of the proximity sensors, any other detection mechanism can be used without departing from the scope of the present invention.
In certain implementations, the controller may also include a GPS module and an inertial navigation module, both modules work together and allows autonomous navigation of the boat, preprogrammed, acceleration regime for the boat, preprogrammed cruise speed, and auto parking.
In certain implementations, the Actuator Mount can be coupled to the actuator frame at one end and the other end can be coupled to the upper fin area of the outboard using fasteners, such as bolts. A rubber dampener, or similar dampening mechanism, can be inserted between the mount surface matting with the anti-ventilation plate located on the lower unit of the outboard. The rubber dampener allows for a slight play since the actuator and propeller will always have a slight misalignment. This allows the propeller to rotate smoothly and also prevent the actuator mount from breaking due to misalignment's threaded holes are made in the upper fin area of the outboard for the mounting bolts. The bolts can be countersunk Allen bolts and can be flush with actuator mounting surface.
The pusher shaft support can be a stainless-steel rod that is of hydrodynamic design for low drag and connects the actuator to the outboard using bolts.
In operation, the propeller can be installed on the outboard and the controller is installed on the boat in a waterproof location. The controller can be connected to the engine rpm sensor, boat speed sensor, and outboard gear shifter. The controller can take the inputs from engine rpm, boat speed sensor, and gear shifter and computes the right pitch angle for the propeller. The controller activates the actuator to move the control rod by a precise amount. The push-pull rod moves the plunger bearing mount. The plunger bearing mount moves the plunger. The plunger rotates the propeller base at a precise angle while keeping its position locked all the time.
In one implementation, the controller can compute and adjust the positive pitch of the propeller as well as the negative pitch. In case the user sets the electronic gear shifter forward, the controller sets the pitch of the propeller to a positive valve and hence the boat moves forward. But if the user sets the electronic gear shifter to reverse, the controller sets the pitch of the propeller to a negative valve and hence the boat can brake very effectively because of reverse thrust and can also move backward. The disclosed device allows for thrust reversal, without changing the gear to reverse on the outboard itself. The outboard can be built without a reverse gear mechanism and still allow the boat to be moved backward and brake more effectively using the disclosed device.
The controller can include a sophisticated algorithm to determine the optimum blade angle for better fuel efficiency, acceleration, and thrust reversal/braking. It takes the controller-less than 2 milliseconds to compute a solution for optimum blade angle and instruct the servo to change the blade angle and keep the blade angle locked until further instruction.
In one implementation, the variable pitch propeller and the controller can also have a built-in collision avoidance algorithm that takes inputs from proximity sensors on the boat hull in strategic locations and sets the pitch to 0 degrees for zero net thrusts in the event of one of the sensors being triggered to reduce damage to the hull.
In one implementation, the controller can also have a GPS module and inertial navigation module, both modules work together and allows autonomous navigation of the boat, preprogrammed, acceleration regime for the boat, preprogrammed cruise speed, and auto parking.
While the foregoing written description of the invention enables one of ordinary skill to make and use what is considered presently to be the best mode thereof, those of ordinary skill will understand and appreciate the existence of variations, combinations, and equivalents of the specific embodiment, method, and examples herein. The invention should therefore not be limited by the above-described embodiment, method, and examples, but by all embodiments and methods within the scope and spirit of the invention as claimed.
This application claims priority from a U.S. Provisional Patent App. No. 63/318,501 filed on Mar. 10, 2022, which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 63318501 | Mar 2022 | US |
