High torque electric motor/flywheel

A high-torque electric motor having a rotor supported by an elongated torque arm comprising a pair of frustoconical-shaped support members. The rotor has a spherical-shaped outer surface and a complementarily shaped stator cavity. The spherical magnetic elements and the conical support members cooperate to brace the rotor against deflection along its rotational axis.

FIELD OF THE INVENTION

This invention relates to electric motors. More particularly, to electric motors having an elongated rotor torque arm mounted to the output shaft to increase the torque applied to the output shaft.

BACKGROUND OF THE INVENTION

An electric motor's power is proportional to its torque and rotational speed. Increasing one or both of these properties increases the motor's power (i.e., its horsepower).

An electric motor has two basic components: a stator and a rotor. At least one of these components includes magnets, whose magnetic fields cause the rotor to move relative to the stator, usually by rotating about a central shaft.

The stator is the stationary electrical component. It typically includes a group of individual permanent magnets or electro-magnets arranged in a way to form a hollow, generally cylindrical shell with one pole of each magnet facing toward the center of the group.

The rotor is the rotating electrical component and typically comprises a generally cylindrical body mounted to a central shaft. The rotor includes a second group of magnets which are arranged around the outer surface in close proximity to the stator's magnets. The interaction between the magnetic fields of these magnets causes Lorentz forces to be exerted upon the rotor causing the rotor to turn, which causes the motor's output shaft to rotate. The distance between the rotor's magnets (where the Lorentz forces are directed against the rotor) and the output shaft represents the torque arm length of the motor. That is, the radius of the rotor determines the amount of torque applied to the output shaft by a given magnetic field.

Currently, in order to increase motor torque the Lorentz forces are increased by using larger magnetic surfaces and/or using more electrical power. While these systems will produce greater amounts of torque, they increase the motor's cost, size and weight.

Increasing the motor's rotational speed, while increasing the motor's power output, generally causes the rotor to vibrate or otherwise become unstable. One example of this instability is that the rotor will deflect or cant along its axis. This deflection and vibration limits how fast a particular motor may be run. One cause of this undesirable deflection at higher rotational speeds is that the support members/torque arms of conventional rotors typically project orthogonally from the rotor shaft and do not have adequate support along the rotational axis (along the rotor shaft).

Similarly, increasing the torque arm length of conventional motors requires the rotational speed to be reduced in order to avoid instability. By lowering rotational speed, the power benefits of the increased torque are offset of the lowered rotational speed.

SUMMARY OF THE INVENTION

The broad purpose of the present invention is to provide an electric motor having an increased torque arm length to increase motor torque, while supporting the rotor along the rotational axis to prevent rotor instability.

It is an advantage of the present invention to provide an electric motor having a rotor frame comprised of two opposed frusto-conically shaped supports.

It is another advantage of the present invention to provide a rotor including a plurality of removable blocks containing the rotor's magnetic elements. The blocks including quick connect/disconnect electrical connections to facilitate removal.

It is still another advantage of the present invention to provide an electric motor having its rotor and stator in a generally ball-shaped configuration to improve rotational balance and to present the largest magnetic surface area over a particular diameter.

It is yet another advantage of the present invention to provide an electric motor having a rotatable output shaft including a rotor assembly and a stator. The rotor includes a support member fixed to the output shaft. The support member is formed from a pair of spaced frusto-conical-shaped walls, each wall is mounted to the output shaft at a first end and tapers radially away from the output shaft and toward the other wall, terminating at a second end. The rotor also includes first magnetic means or elements mounted to the support member. The stator rotatably receives the rotor and includes second magnetic means or elements which are arranged around the stator effective to cause the rotor to rotate and turn the output shaft.

It is still yet another advantage of the present invention to provide a high-torque electric motor comprising a rotor assembly mounted to a central output shaft and a stator having a housing which defines an internal rotor-receiving cavity. The rotor assembly comprising a two cone-shaped support member, each having a hub fixedly mounted to the output shaft. Elongated annular walls taper away from the hubs at an angle and terminates at an outer end, wherein the support members are mounted to the output shaft such that the annular walls taper toward each other. The rotor assembly also includes a plurality of electromagnets mounted to the support members at their outer ends and are spaced evenly around the output shaft. The stator including a plurality of permanent magnets that are axially spaced evenly about the rotor-receiving cavity.

It is still yet another advantage of the present invention to provide an electric motor that rotates an output shaft, comprising: a first rotor support shell having a cone-shaped wall which tapers from a first narrow end to a first wide end, wherein the first rotor support shell is fixed to the output shaft at the first narrow end; a second rotor support shell having a cone-shaped wall which tapers from a second narrow end to a second wide end, wherein the second rotor support shell is fixed to the output shaft at the second narrow end, wherein the shells are mounted to the output shaft such that the shells taper toward each other; a toroid-shaped mounting base which is fixedly mounted to the first and second wide ends; a plurality of support arms which extend from opposite sides of the mounting base, the support arms running generally parallel to the output shaft, the arms are axially spaced evenly around each side of the mounting base, wherein an outer peripheral surface of the mounting base and an outer peripheral surface of the arms cooperate to form a ball-shaped magnet-mounting surface; a plurality of wedge-shaped electromagnets, the electromagnets are mounted to the mounting base and the arms at the magnet-mounting surface, the outer periphery of each of the electromagnets cooperatively define a ball-shaped outer surface.

Still further objects and advantages of the invention will become readily apparent to those skilled in the art to which the invention pertains, upon reference to the following detailed description.

DETAILED DESCRIPTION OF THE INVENTION

Referring now toFIG. 1, an improved electric motor10is shown including a stator12having a housing14which contain a magnetic elements or means16, such as a plurality of permanent magnets. Motor10also includes a rotor assembly18which is fixedly mounted to a central output shaft20. Shaft20is free to rotate on bearing means21that are mounted to stator housing14. In the preferred embodiment, stator housing14is formed in two separable sections14A,14B which are joined along side flanges23by conventional means, such as mechanical fasteners. In one embodiment, a stator cover plate14′ encloses the rotor assembly18when mounted within the generally cylindrical stator cavity. In this embodiment, this plate14′ includes the bearing means21that engage the output shaft20.

Rotor assembly18includes a support member22that is fixed to the output shaft20and magnetic elements or means24peripherally mounted to support member22.

Support member22includes a pair of substantially identical conically or frusto-conically shaped shells26,27formed from a relatively thin, but rigid non-ferrous material, such as aluminum sheet. Shells26,27are mounted concentrically to shaft20such that their wide ends or bases26A and27A face each other while narrow ends or hubs26B,27B face in opposite directions. In this manner the side walls26C,27C of the shells taper toward each other and away from the central shaft20. In the preferred embodiment walls26C,27C both form a forty-five degree angle with shaft20. Brackets28rigidly couple the hubs26B,27B to shaft20in a conventional manner, such as welding or mechanical fasteners.

In the preferred embodiment, each shell26,27terminates at an annular lip30having an outer surface30that is parallel to the rotational axis of shaft20. A toroid-shaped mounting body32having a generally cylindrical inner surface32A which abuts and is fixed to outer surface30A of each shell26,27. Walls26C,27C and body32cooperate to define an internal opening or cavity34. Body32is preferably formed from a relatively lightweight, durable material, such as aluminum and, as will be discussed in greater detail below, the outer surface32B of body32is preferably outwardly curved or convex in shape. As best shown inFIG. 8, body32also includes a series of spaced support members32C which run beneath the outer surface32B.

Magnetic elements24are mounted to outer surface32B of body32. In the preferred embodiment, these magnetic elements24are electromagnets formed from electrically conductive windings38wrapped around a core40of highly permeable magnetic material, such as iron or steel which runs along the longitudinal length of each electromagnet. The electromagnets24are electrically coupled to a source of electrical energy, such as a battery, via a rotary electrical interface42and armature wiring43that passes through cavity34and runs to each electromagnet.

It should be appreciated that each core40receives multiple individual electrical wires, which cooperatively form windings38that are wrapped around the core40. In the preferred embodiment of the invention and as best shown inFIG. 3, the windings38only cover the outer portion of the core40and rest upon a seat40′ that extends from the approximate center of the core. Further, the radially outermost wires38′ wrapped around the core are preferably flattened to maximize the surface area of the portion of the windings38that are in closest proximity to the stator's magnetic elements16.

In one embodiment, the electromagnet's windings38and core40are encased in a high dielectric strength, water resistant, resilient material41which dissipates heat from the electromagnet24similar to the dielectric materials surrounding the coils of conventional scrap handling electromagnets. This dielectric material41is retained by a shell or outer cover25formed from a thin layer of non-ferrous material, such as aluminum.

Referring now toFIGS. 1,2, and4, a plurality of electromagnets24are spaced equally about the outer surface32B. The number of rotor magnetic elements can vary, but in one embodiment, six electromagnets24are spaced about the rotor. These electromagnets24are preferably generally rectangular having their long side running parallel to shaft20. It should be appreciated that the even spacing of substantially identical electromagnets24produces a rotor assembly18which is weighted evenly about the output shaft20to ensure the rotor is balanced. Dynamic balancing/testing of the rotor assembly18and adding or removing material from the rotor, such as to/from the support member22will further ensure that rotor assembly18is balanced.

As best shown inFIGS. 2 and 3, each electromagnet24is preferably curved or rounded, such that the outer surfaces44of the electromagnets24cooperate to present a generally spherical or ball-shaped appearance. In one embodiment, each point on the outer surface44of every one of the electromagnets, when mounted to the rotor assembly18, is a fixed distance or radius from a given centralized point along the centerline45of shaft20. It should be appreciated that by curving the electromagnets24, more surface area of the outer surface44can be maximized for a particular size/diameter rotor. Additionally, the magnetic forces exerted on the opposing inwardly curving (i.e., toward the shaft20) longitudinal ends46of the electromagnets24resist axial deflection of the rotor to further balance the rotating rotor assembly18. Magnetic elements24are coupled to body32using conventional fastening techniques, such as welding (e.g., core40to the body32) or mechanical fasteners.

In all embodiments, the longitudinally running windings38must form an angle with the rotational axis of shaft20that is less than forty-five degrees. If the windings curve beyond forty-five degrees relative to the shaft, the resulting magnetic forces will begin to work against the desired rotation of the rotor.

Housing14of stator12includes an internal cavity48that is shaped complementary to the ball-shaped outer surface44of the rotor assembly18. The stator magnetic elements16are mounted within this rotor-shaped cavity48and are generally concave elongated rectangular magnets that are spaced evenly around the longitudinal axis of the cavity. In the preferred embodiment, stator magnetic elements16are high strength permanent magnets which are arranged within housing14with the inwardly directed portion (i.e., toward shaft20) of each magnet16has the same polarity. In the preferred embodiment, electromagnets24are synchronized/controlled such that half of the electromagnets are energized, while the remaining electromagnets are deactivated (i.e., not energized) at any given time. In this manner, one half of the circumference of the rotor will be generating a magnetic field and producing a large surface area for magnetic pull. In the preferred embodiment, every other electromagnet24will be activated as they pass from one permanent magnet to the next to maximize the attractive/repulsive forces. Typically, the energized half of electromagnets are deactivated when they are just crossing the midway point of the permanent magnets' surface. At that time, the other, previously deactivated electromagnets are energized.

It should be appreciated that various electromagnet timing and permanent magnet polarity arrangements may be employed using the current motor10. For example, in other embodiments, each adjacent magnet16has the opposite polarity (i.e., magnets16alternate between positive and negative polarity around cavity48). In this manner, magnets16alternatively repel and attract the rotating electromagnets24in the rotor assembly18. In another non-limiting example, instead of pulsing the electromagnets24on and off, the polarity of the magnets24may be reversed to both attract and repel the magnetic fields from the stator's permanent magnets16.

Importantly, by supporting the rotor's magnetic elements24with a tapered frame formed by opposed frusto-conical shells, the rotor is braced against any deflection of vibration along the rotational axis. This axial support/bracing permits the distance between the magnetic elements24and the rotational axis (shaft20) to be extended, thereby increasing the torque of the motor for a given amount of electrical energy put into the motor. This axial bracing also enables the rotor to be rotated at a faster rotational speed compared to conventional rotors without unbalancing the motor.

The above-described pulsing/timing of the electromagnets24to maximize the magnetic field interaction between the rotor and stator in combination with the capability of elongating the torque arm (i.e., by increasing the radial distance between the output shaft20and the electromagnets' outer surface44) using the conical support22result in motor10having increased horsepower and torque than comparably sized conventional motors.

By curving the magnetic elements of the rotor (and its complementarily shaped stator) the present invention maximizes the magnetic surface area, thereby maximizing the magnetic forces exerted. Additionally, the inwardly curving shape of the rotor assists in balancing the rotating rotor.

Further, the windings38and core40of the electromagnets are comparatively heavy relative to the other rotor components. This mass is mounted to the rotor shaft at an extended distance compared to conventional motors, which use a comparable amount of electrical energy, as discussed above. This balanced heavy weight revolving about the shaft20, results in a flywheel-like high mass moment of inertia. This additional moment of inertia, compared to conventional motors, results in less energy required to keep the rotor assembly18rotating at a given speed (once it is brought up to that speed).

As best shown inFIGS. 7 and 8, the electromagnetic elements24are removably mounted to the rotor assembly18. That is, each of the electromagnets24are individually mounted and retained within a toroid-shaped support tray56which is fixed to the outer surface32B of the mounting body. In this embodiment, tray56extends beyond mounting body32and is supported on both sides by arms50.

Referring now toFIGS. 1, and5-8, in the preferred embodiment, the magnetic elements24of rotor assembly18extend beyond the body32, thereby increasing the surface area of elements24. To keep the weight of the support structure to a minimum, a plurality of support arms50, equal in number to the number of magnetic elements24mounted to the rotor are mounted to each sidewall52of the body32. Support arms50include a contoured mounting rail53that is supported by an angled buttress54mounted therebeneath. Each arm50is fixedly mounted to the sidewall52by conventional means. In one embodiment, a support lip55extends along the inner or bottom surface32A of body32and may abuttingly engage lip30. The mounting rail53is curved to follow the contour of the rounded support tray56located beneath the magnetic elements24and retention blocks68.

Tray56includes a pair of annular walls58mounted on opposite ends of the tray which cooperate with the bottom tray wall59to form a radially outwardly facing recessed area60. Bottom wall59is shaped complementary to surface32B and presents a generally curved surface while walls58preferably extend away from bottom59perpendicular to the rotational axis of shaft20. Tray56is preferably formed from a relatively lightweight, durable, non-magnetic material, such as aluminum.

In this embodiment, each armature wire43terminates in electric socket means62that is in communication with recessed area60. Each electromagnet24includes complementary-shaped electric plug means64which is received by socket means62.

As shown inFIGS. 3 and 7, each electromagnet24is configured as a block66having a wedge or trapezoidal-shaped cross-section. The base66A of the blocks66is placed upon the tray bottom59with side walls66B tapering inwardly to the upper face66C. Adjacent to each magnet block66is a retention block68, which also has a wedge or trapezoidal-shaped cross-section. Each retention block68is shaped to abuttingly engage and hold the two adjacent magnet blocks66to the tray56and rotor assembly. That is, each retention block68is mounted such that the side walls68B abut the side walls66B of the two adjacent magnets. A plurality of removable mechanical fasteners, such as bolts70couple blocks68to the arms50and base32which have complementary threaded bores72. In the preferred version of this embodiment, the number of arms50equals the number of blocks68(which equal the number of electromagnet blocks66) mounted to the rotor assembly18. The interference/wedging fit between the mounting wedges68and the electromagnetic blocks66rigidly couples the rotor's magnetic elements to the rotor assembly, while enabling a user to readily remove one or more electromagnets24for repair or servicing.

As shown inFIGS. 1 and 8, additional mechanical fasteners70mount the retention blocks68to support member32C.

In an alternate embodiment of the motor, denoted100, shown inFIG. 9, the magnetic elements24are directly and fixedly mounted to the mounting body32. Support arms50are centered mounted beneath magnets24to provide additional support. While this embodiment simplifies the construction of the motor100, by eliminating the mounting blocks68, plugs64,66and retention tray56, the motor cannot be readily repaired if one of the electromagnets24fails.

In still another alternate embodiment of the motor, denoted200, shown inFIG. 10, the magnetic elements24of rotor assembly18do not extend beyond the body32. This embodiment reduces the radially forces acting on the support member22, but the reduced surface area of the magnets also reduces the torque-producing magnetic forces.

The invention has been described in an illustrative manner, and it is to be understood that the terminology, which has been used, is intended to be in the nature of words of description rather than of limitation. It is to be understood that the invention is not limited to the exact construction which has been illustrated and discussed above, but that various changes and modifications may be made without departing from the spirit and the scope of the invention as is more fully delineated in the following claims.