WO1999045624A1

WO1999045624A1 - An improved electric motor

Info

Publication number: WO1999045624A1
Application number: PCT/US1999/004698
Authority: WO
Inventors: Edward Neal Scheffer; Gerald Wayne Scheffer
Original assignee: Edward Neal Scheffer
Priority date: 1998-03-04
Filing date: 1999-03-03
Publication date: 1999-09-10
Also published as: AU2892099A

Abstract

A highly efficient electric motor for converting electrical energy into rotational mechanical energy having at least one bobbin (3) wound stator coil through which passes a ring rotor upon which a plurality of permanent magnets are mounted. The permanent magnets are circumferentially mounted around the axis of rotation of the ring rotor having their North poles alternatively facing toward and against the direction of rotation. The bobbin (3) wound stator coils receive electrical signals from an electronic controller, causing the coils to generate magnetic fields which attract and then repel the permanent magnets mounted on the ring rotor (1). This electric motor may be ganged together with one or more other motors of this design to increase the mechanical power output. This electric motor may also be driven by an external torque applied to the output shaft (8) of this motor whereby mechanical energy may be converted to electrical energy.

Description

1

AN IMPROVED ELECTRIC MOTOR

Background

Field of Invention - The field of this invention is in the realm of electric motors.

Description of Prior Art - Electric motors are at the heart of many machines used in both homes and factories. When a quiet, nonpoUuting energy source is needed to move something, whether it is a toothbrush or a golf cart, the answer is to use an electric motor. For the foregoing reasons, including the need for a highly efficient, long lasting electric motor for automobile propulsion, an improved electric motor will be of a great benefit.

Summary

The present embodiment of the invention is directed toward the need for a highly efficient, long lasting and powerful electric motor. This embodiment comprises a housing, a ring rotor with a plurality of permanent magnets attached, bobbin wound stators affixed to the housing through which the ring rotor completely passes, one set of planet gears for torque transmission, another set of planet gears for speed reduction, a sun gear for powering an output shaft, and a plurality of support bearings.

Drawing Figures

These and other features, aspects and advantages of the present embodiment of the invention will become better understood with regard to the following description, appended claims and accompanying drawings where:

Fig. 1 shows a head-on view of the electric motor without the housing Fig. 2 shows a sectioned side view of the electric motor with a cut-away housing. Reference Numerals in Drawings

I rotor 2 permanent magnet (alternating poles)

3 bobbin wound stator coil 4 sun gear - output/driving 5 support bearing 6 planet gear - torque transmitting 7 planet gear - speed reducing 8 output shaft 9 rotor gear teeth 10 air bearing shaft

I I planet gear shaft 12 housing 13 air bearing chamfer 14 motor controller 15 hall effect sensor 16 orifice in the air bearing shaft

Description of the Invention

In the preferred embodiment this electric motor uses a housing 12 that completely encloses the motor apparatus. The housing 12 can seal the apparatus from the outside environment allowing a vacuum to be drawn inside the housing. The vacuum reduces the amount of air resistance the moving parts of the motor may generate and also reduces the propensity of the difference of electrical potential present in the motor to cause arc-over. Both air resistance and electrical arc-over can reduce the efficiency of the electric motor. Efficiency is important because this electric motor configuration is trying to maximize the conversion of electrical power into useful mechanical torque.

The ring rotor 1 has a predetermined number of permanent magnets 2 affixed around the ring rotor's 1 periphery in an evenly spaced manner. The North magnetic poles of the permanent magnets 2 are oriented in an alternating direction. As an example, a randomly selected magnet may have it's North pole facing in the direction of the ring rotor's rotation. The adjacent magnet will have it's North pole facing opposite the direction of the ring rotor's rotation. In the present embodiment 24 permanent magnets are used. The number of permanent magnets used in a different embodiment would be dependent on the selected diameter of the ring rotor 1 and the 3 amount of output torque desired. Also in the present embodiment the permanent magnets are attached to the ring rotor 1 by the means of an adhesive which is non- outgassing in a vacuum environment. Other attachment methods may be easily contemplated by those of ordinary skill in the art. As an example, but not a limitation, the attachment method could be by the means of a press fit or by the use of a screw type fastener.

Each permanent magnet 2 has a truncated disc shape with a substantially rectangular section removed from the end facing in the ring rotor's 1 axial direction. The removed section allows the permanent magnet to fit over the ring rotor's periphery and be permanently mounted thereon. The ring rotor 1 is fabricated from a nonconductive and nonmagnetizing material to reduce and thereby minimize stray eddy currents and stray magnetization that has the potential to reduce the efficiency of the motor. The width of the permanent magnet 2 may be selected empirically to maximize the motor torque for a given amount of electrical power. In the preferred embodiment, a total of six bobbin wound stator coils 3 are used to attract and repulse the permanent magnets located around the periphery of the ring rotor 1. This attraction and repulsion are what induce the movement the ring rotor 1 that is translated into the torque on the output shaft 8. The bobbin wound stator coils 3 are affixed to the housing 12 and completely encircle the ring rotor 1 with clearance for the permanent magnets 2 to pass through them unimpeded. Each pair of bobbin wound stator coils 3 in this embodiment are separated by an angle of 37^°. Other embodiments may use a different number of coil sets and a different angle of pair separations. This would depend on the output torque and motor efficiency that is trying to be achieved. More coil sets could require that more electrical power be applied to the motor.

The ring rotor 1 has gear teeth 10 cut along the entire length of its inner periphery. These teeth mesh with the torque transmitting planet gear 6 teeth. The planet gears 6 are arranged in an evenly spaced manner around the interior of the housing 12. The planet gears 6 are supported by their shafts 11 whose ends are, in turn, supported by bearings located in the motor housing 12. Mounted on the same 4 shaft with the torque transmitting planet gear 6 is a smaller speed reducing planet gear 7. The speed reducing planet gear 7 engages the output shaft sun gear 4. Thereby transmitting the torque received by the torque transmitting planet gear 6 to the output shaft sun gear 4 but at a reduced rotational speed. The output shaft sun gear 4 is mounted on a shaft which is in turn supported on it's ends by bearings located in the motor housing 12.

The ring rotor 1 is held in position and supported by a number of air bearings 5. Other types of support structures are possible, including, but not limited to ball bearings, roller bearings, and needle bearings. However, air bearings minimize friction and therefor maximize motor efficiency. The air bearings 5 are capable of supporting both the axial and the radial forces that are generated by the ring rotor 1. The air bearings 5 have a chamfered rotational surface that matches the chamfer 13 present on the ring rotor 1. The air bearings 5 are mounted on an air bearing shaft 10, extending to and through the motor housing 12. An orifice 16 runs through the center of the air bearing shaft to allow compressed air to travel from an air source outside the housing

12 to the supporting air bearing 5. The supporting air bearings 5 are placed equidistantly apart and in the preferred embodiment three are used for the ring rotor 1 support. Air bearings of this type are well known in the art.

In the preferred embodiment of this invention the bobbin wound stator coil 3 uses a superconducting material to reduce 1²R energy losses due to bobbin wound stator coil resistance. Bismuth-based compounds are being fashioned into superconducting wires and coils. These can be cooled with cheap and readily available liquid nitrogen. These materials are called high-temperature superconductor.

Theory of Operation

The bobbin wound stator coils 3 are placed around the periphery of the ring rotor 1 in three sets of two coils each for a total of six coils. Each set of coils receives the same waveform of voltage at the same time. The waveforms are generated by a motor controller. However one coil in each set receives the waveforms 30^° out of phase from the other coil in the set. This results in the permanent magnets 2 being 5 pulled into the coils and then alternately repulsed out of the coils in a sequential manner. The permanent magnets 2 are being pulled along much like the magnetic core of an solenoid. But in this case the motion is continuous and rotational rather than periodic and linear.

A Hall Effect sensor 15 mounted in a fixed position in the motor housing 12 generates an electrical signal each time a permanent magnet 2 mounted on the ring rotor 1 passes by the sensor's position. This signal is used in a logic circuit to feed back the rotor speed to the motor controller 14. This feedback allows the motor controller 14 to smoothly accelerate the ring rotor 1 up to a preset speed and then to monitor and maintain that set speed.

The configuration of this invention allows a number of individual motors to be sandwiched together in a chain to increase the torque output.

This invention can also be used as a device to generate electrical power from a mechanical torque placed in the output shaft 8.

Claims

WHAT IS CLAIMED IS:

1. A high efficiency electric motor comprising: a housing; a ring rotor rotatably mounted in said housing; a plurality of permanent magnets mounted onto said ring rotor; and a plurality of fixed stationary stator coils through which passes said ring rotor.

2. The high efficiency electric motor of claim 1 further comprising: a bearing means for supporting the ring rotor whereby said ring rotor may be located in a substantially precise position relative to the bobbin wound stator coils and allowed to rotate within side housing; and a means for coupling the rotation of the ring rotor to an output shaft.

3. The high efficiency electric motor of claim 2 wherein: the ring rotor supporting means comprises a plurality of air bearings; and the ring rotor coupling means to the output device comprises a plurality of torque transmitting and speed reducing planetary gears.

4. The high efficiency electric motor of claim 1 further comprising: said housing sealed from the surrounding environment and capable of having a vacuum drawn in the interior of said housing thereby reducing air friction losses in the interior of said housing.

5. The high efficiency electric motor of claim 1 further comprising: a sensor means for detecting the rotational speed of said ring rotor; and a controller means for sending an appropriate electrical signal at an appropriate time to the plurality of stator coils.

6. The highly efficient electric motor of claim 1 wherein: said stator coils are fabricated from a superconductive material and cooled with liquid nitrogen.

7. The highly efficient electric motor of claim 2 wherein: the means for supporting the ring rotor is fabricated from a substantially nonmagnetic and nonconductive material; the ring rotor is fabricated from a substantially nonmagnetic and nonconductive material; the housing is fabricated from a substantially nonmagnetic and nonconductive material; and the rotational coupling means is fabricated from a substantially nonmagnetic and nonconductive material.