RELATED APPLICATION

This application claims the benefit of priority of U.S. Provisional Patent Application No. 63/180,140 filed on 27 April 2021, the contents of which are incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

The present invention relates generally to switched reluctance electric machines including motors and generators, and more particularly, but not exclusively, to both rotary and linear motors and generators.

BACKGROUND OF THE INVENTION

Electric Machines of several types are commonly used in industry. They are characterized by their size, output torque or force, maximum speed, efficiency and other properties.

An important property of an electric motor is the maximum continuous torque or force output relative for a given motor size and weight.

Another important property is the ease of assembly during the motor or generator manufacturing process.

Most common motors used in the industry are AC induction motor and Synchronous Rotary motors.

Induction motors are of simple construction, and can be run by simple connection to an AC three phase power source. A disadvantage of the induction motor is that it has a low power density and its speed or angular position cannot usually be precisely controlled.

Another type of motors, Synchronous Rotary Electrical Motors (SRE) include a stator and a rotor. The stator includes a number of poles around which electrical windings are placed. The rotor includes permanent magnets. The magnetic flux produced by the magnets interacts with the current running in the winding to produce working torque. Desired working torque is obtained by controlling the current in windings. SRE motors are driven by an electronic controller. The power density of the SRE motor is high, and its speed and angular position may be very precisely controlled by the electronic controller. A disadvantage of these motors is the fact that they include permanent magnets. Permanent magnets rotate in proximity with the poles and create a magnetic field of alternating direction in the pole material, thus generating hysteresis and eddy current power losses. These power losses rapidly increase with the rotating speed, thus limiting the maximum speed and reducing the efficiency of these motors at high speed.

Additionally, the SRE include costly and environmentally unfriendly magnets.

Switched Reluctance Motors (SR) constitute another type of rotary motor. SR motors include magnetic circuits that are alternatively opened and closed by the rotor rotation. A geometric design ensures that ferro-magnetic material traverses air gaps of the magnetic circuits during rotor rotation. SR motors can be designed without permanent magnets. Advantages of SR motors are their higher efficiency at high speed and potential lower cost since they do not include permanent magnets.

Examples of SR motors are shown in the following patents and applications, JP2011078202A, US20180006510A1, US8624458, JP2008252976A, US7312549,

WO2020264374A1, US9112386, JP5223523B2, CN109742872B, CN108599492B,

WO2018077788A1, and US20100295389A1.

In all these prior art documents, strong variable attractive electromagnetic forces are applied on rotor and stator at the air-gap. These forces are transverse, for example axial or radial, to the normal rotary or linear movement of rotor and they induce strong acoustic noise and require strong and heavy rotor and stator construction.

In the scope of this disclosure, we use the term “transverse” to refer to a direction of a force or vector which is orthogonal to the normal movement of a motor moving part.

SUMMARY OF THE INVENTION

It is an object of the present embodiments to provide an SR motor having a relatively low inertia rotor with balanced attractive force at the air-gaps.

A further object of this patent is to provide a relatively high torque density.

Another object of this invention is to provide an electric machine with a relatively simplified assembly.

The present embodiments may relate to a switched reluctance (SR) rotary electrical machine in which the magnetic flux lines run in planes mainly parallel to the motor shaft and to linear motors in which the magnetic flux runs in planes mainly perpendicular to the linear path of the rotor.

An SR machine, according to the present embodiments may comprise a flux motor wherein the flux in the magnetic circuits surrounds the winding in a plane parallel to the motor shaft. As will be shown, the number of poles need not be limited by the windings, and a large number of poles can be used. For a given number of windings and motor volume, the available torque increases with the number of poles.

In the scope of the present embodiments, the motor described is an electrical machine that may be used as a motor to output mechanical power when electrical power is input, or as a generator, to output electrical power when mechanical power is input to it.

The present embodiments may increase the torque available for a given motor volume.

The present embodiments may reduce the moment of inertia of the rotor.

Transverse forces applied on the rotor according to the present embodiments may be minimized, thus reducing stress, resonance and acoustic noise. The reduction in stress may improve the lifetime of the machine.

Yet another advantage according to the present embodiments, may comprise a smaller number of windings being required, no longer dependent on the number of yokes.

Yet another advantage is a simplified assembly procedure, resulting in reduced production cost.

The electric machine, including a generator and a motor, according to the present embodiments, may be applied for both rotary and linear motors.

A rotary embodiment according to the present invention may comprise a rotor, and a stator.

The rotor may comprise a shaft which rotates inside a motor stator by means of bearings.

A number, r, of rotor-phases, are mounted and fixed to the shaft.

Here, we shall further refer to r as the ‘number of phases’ .

In each rotor-phase, at a shaft center location, is mounted cup-shaped part, herein “Cup”, concentric with the shaft. Each Cup has a cylindrical part with a number PI of inward and outward protuberances at the same number PI of radial positions.

The stator may include the same number r of stator-phases.

Each stator-phase may include a number P2 of yokes made of magnetizable material, forming magnetic circuits. Yokes have a U shape parallel to the shaft, and are distributed around the shaft. Each stator phase also includes at least one annular coil, concentric with the shaft. The yokes are disposed to surround the concentric coil, traverse it, and provide an opening to receive the Cup cylindrical part.

We shall further refer to motor-phase as the group of a rotor-phase, a stator-phase with its coil(s).

When the rotor rotates, the Cup also rotates freely inside the yoke openings. Whenever the rotor angular position is such that an inward and outward protuberance of the Cup traverses the yoke, two very thin air-gaps are obtained, resulting in a low reluctance of the yoke magnetic circuit. For rotor angular positions, where the protuberance does not traverse the magnetic circuit, a high reluctance is obtained for the yoke magnetic circuit.

The relative angular positions of the Cup protuberances and the magnetic circuit are designed so that the total reluctance varies periodically from a maximum value to a minimum value several times for each turn of the rotor.

Electric current run in the coil(s) generates magnetic flux and creates an attractive force between the cup protuberances and the yokes. The attractive force may have a value which varies in size and direction according to the relative distance between the Cup protuberances and the Yokes, producing a torque between the rotor-phase and the stator-phase. A current controller adjusts the current(s) in the coil(s) to produce the desired motor torque.

In the case of r < 3, that is only 1 or 2 motor-phases, the motor may be unable to start and may need additional parts. Such 1 or 2 phase motors may also induce a high torque ripple during rotation.

In case of r >= 3, either the rotor-phase or stator-phase are angularly shifted for each motor- phase, so that current controller is able to start and run the motor with a minimum torque ripple.

According to embodiments of the herein described motor, due to the annular shape of the coils and the circular distribution of the yokes, for a given motor size, the number P2 of yokes per motor-phase may be increased and optimized to be able to generate a high torque.

In embodiments of the herein described motor, attraction forces applied on the rotor at the inward and outward protuberances are of opposite direction and may cancel the total attraction force on the stator. Elastic deformations of the rotor are thus avoided, the Cup thickness can be reduced to a minimum and rotor inertia significantly reduced.

In embodiments of the herein described motor, the number of coil(s), one per motor phase, may be significantly reduced compared to the relatively high number of coils needed for prior art motors, where most commonly need 3 coils per stator pole.

According to an aspect of some embodiments of the present invention there is provided a switched reluctance rotary electrical machine comprising a rotor rotatable about a rotary axis and at least one stator, the at least one stator comprising a plurality of yokes distributed circumferentially around the rotary axis, the plurality of yokes each comprising a hollow, the hollow comprising a lengthwise axis towards an opening at one end of the yoke, the respective lengthwise axes being aligned in parallel with the rotary axis, the at least one stator further comprising a winding coil, the winding coil forming a ring around the rotary axis and extending through the respective yoke hollows, the rotor comprising a base extending radially outwardly from the rotary axis and a cylinder wall extending circumferentially around the radial axis, the cylinder wall comprising protrusions, the cylinder wall and the protrusions sized to fit within the yoke openings the protrusions to generate airgap variations with rotor rotation thereby to produce torque when current is run in the winding coil.

Embodiments may comprise at least three stators, the rotor having protrusions for each of the three stators, the protrusions being evenly spaced, the protrusions for each of the respective stators being offset from protrusions of neighbouring ones of the stators.

In embodiments, two of the stators share a single rotor, the single rotor comprising two oppositely extending cylindrical walls and respective openings of the yokes of the two of the stators being in facing directions.

In embodiments, each stator comprises a ring component with each one of the plurality of yokes integrally built thereon.

In embodiments, a total number of winding coils is equal to a number of the at least one stator. This contrasts with the prior art where the number of coils is generally related to the number of polls.

In embodiments a number of protrusions on a given rotor is equal to a number of yokes of the, stator, in other words the number of polls.

A flux direction of airgap flux may be in a radial direction within the yoke openings, with respect to the rotary axis.

In embodiments, the protrusions are configured to enter and leave respective yoke openings, thereby causing varying of the airgap flux during rotation.

According to a second aspect of the present invention there is provided a switched reluctance linear electrical machine comprising a mover and a stator, the stator comprising a base and a rail extending upwards from the base, the rail having a longitudinal direction and first and second sides, the rail comprising toothed rail protrusions extending outwardly from at least a first side, the mover comprising at least one yoke arranged on a carriage, the yoke comprising an element shaped to fit over the rail, a winding fitting around the yoke and the yoke comprising yoke protrusions to face the rail protrusions.

Embodiments may include at least three yokes, the protrusions for each of the respective stators being offset from protrusions of neighbouring ones of the yokes.

In the linear motor embodiments, a total number of winding coils may be equal to a number of yokes.

In embodiments, a flux direction of airgap flux is orthogonal to a travel direction of the carriage along the rail. In embodiments, the respective rail protrusions and the yoke protrusions are configured to meet and separate, thereby causing varying of the airgap flux during motion.

In one alternative, the yokes are linearly arranged along the rail.

In a second alternative, there are three or more rails in parallel and the carriage comprises three or more yokes arranged in parallel.

In a further alternative embodiment, the rail comprises two rails in parallel, the yoke comprising a T shaped element fitting between the two rails, the rail protrusions facing inwardly and the yoke protrusions facing outwardly.

In another alternative embodiment, the rail protrusions face widthwise outwardly from the rail and the yoke comprises a concave element fitting over the rail, the yoke protrusions facing inwardly towards the rail protrusions.

Unless otherwise defined, all technical and/or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the invention, exemplary methods and/or materials are described below. In case of conflict, the patent specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and are not intended to be necessarily limiting.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Fig 1 is an overview of a three phases motor according to an embodiment of the present invention;

Fig 2a is an exploded view of a one motor-phase according to an embodiment of the present invention;

Fig 2b shows the rotor Cup of the motor-phase of Fig 2a with the inward and outward protuberances;

Fig 2c shows the stator yoke 104a of the motor-phase of Fig 2a;

Fig 3 is an axial cross sectional view of a yoke according to an embodiment of the present invention to show the two thin air-gaps between protuberances and yoke and the flux path;

Fig 4a shows a three-phase motor of an embodiment of the present invention where two rotor-phase Cups are implemented in one piece;

Fig 4b is a view of the rotor-phase with two Cups of Fig 4a;

Fig 5a and 5b show yokes implemented in one part made of bulk or composite material, according to an embodiment of the present invention; Fig 6a is a view of a linear motor built according to an embodiment of the present invention with one toothed linear bar and where the yokes sliding and serially connected;

Fig 6b is a view of a single yoke of the linear motor shown in Fig 6a;

Fig 7 is a view of a linear motor built according to an embodiment of the present invention with three toothed linear bars and where the yokes are sliding and laterally connected;

Fig 8a is a linear motor according to an embodiment of the present invention wherein multiple yokes are serially connected and static, and a carriage with a short toothed bar slides inside the opening of the yoke; and

Fig 8b is a view of the carriage of the embodiment of Fig. 8a, showing the toothed shape.

DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION

As explained above, the present invention relates generally to switched reluctance electric machines including motors and generators, and more particularly, but not exclusively, to rotary motors or generators in which the magnetic flux lines runs in planes mainly parallel to the motor shaft and to linear motors in which the magnetic flux runs in planes mainly perpendicular to the linear path of the rotor.

A switched reluctance rotary electrical machine according to the present embodiments comprises a rotor extending along a rotary axis and one or more stators with yokes distributed around the rotary axis. The yokes are hollow and open at one end, the hollows and openings being aligned in parallel with the rotary axis. The stator has a winding coil in the form of a ring around the rotary axis which extends through the yoke hollows. The rotor extends outwardly from the rotary axis and has a cylindrical wall with protrusions. The cylindrical wall and protrusions fit within the yoke openings and rotate so that the protrusions rotate between the yokes. Excitation of the yokes by the coils causes the rotor to rotate by continually pushing the protrusions to the next yoke airgap.

A further embodiment relates to a switched reluctance linear electrical machine. A mover moves along a stator, the stator comprising a base and a rail extending upwards from the base. The rail has a longitudinal direction and outwardly facing sides, the rail comprising toothed rail protrusions extending outwardly from at least a first side. The mover is made of one or more yokes arranged on a carriage, the yoke comprising an element shaped to fit over the rail. A winding fits around the yoke and the yoke comprises yoke protrusions that face the rail protrusions. In one embodiment a single rail has protrusions which face outwardly and the yoke is concave and fits over the rail, having protrusions facing inwardly. In another embodiment, two rails are provided and the yoke fits between them. In this case the rail protrusions face inwardly and the yoke protrusions face outwardly.

Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not necessarily limited in its application to the details of construction and the arrangement of the components and/or methods set forth in the following description and/or illustrated in the drawings and/or the Examples. The invention is capable of other embodiments or of being practiced or carried out in various ways.

Herein, the following examples describe three-phase embodiments. However the skilled person will be aware that different number of phases may be considered.

As mentioned above, for a phase number smaller than 3, additional start procedures or arrangements may be required.

A phase number greater than 3 may be used to lower torque ripple.

Referring to Fig 1, a three-phase motor 100 is shown, built according an embodiment of the present invention. The motor 100 includes three “motor-phases” 100a, 100b and 100c and a common shaft 101. Each motor-phase includes a rotor (rotor-phase) 102a, 102b, 102c fixed to the shaft and a stator (stator-phase). Each stator-phase includes a number of yokes 104a, 104b, 104c, distributed symmetrically around the rotation axis of the shaft 101. Yokes 104a are made of magnetizable material such as laminated electric steel or magnetic composite.

Each stator-phase may also include a ring-shaped coil 105a, 105b, 105c which traverses the yokes of the respective stator-phase. Each rotor-phase 102a, 102b, 102c has a cylindric part with inward and outward protuberances 103a, 103b, 103c.

The shape of the rotor-phases like 102a is a cup shape (Cup) shown in Fig 2b, comprising a radially-extending base extending outwardly from the rotor axis, and a cylinder wall extending circumferentially around the rotor axis. Thus the cylindrical outer wall of 206 extends parallel to the axial direction of the shaft. Protuberances 103a etc. protrude inwardly and outwardly of cylinder 206. Each rotor-phase is fixed to the shaft and rotates with the shaft. The protuberances 103a etc. are made of magnetizable or ferrous material.

The shape of the yokes, such as 104a, is shown in Fig 2c, and an exploded view of the motor-phase 100a is shown in Fig 2a. The coil 105a is inserted in the opening of the U-shaped yokes 104a, as indicated by arrow 207, and traverses all the yokes of the motor-phase. The rotor- phase 102a is also inserted in the opening of the U-shaped yokes such as 104a, as indicated by arrow 208.

During shaft rotation, the rotor-phases also rotate and the rotor-phase protuberances 103 a etc. traverse the opening of the U-shaped yokes 104 etc. The size and shape of the protuberances 103a etc. is designed to create two narrow air-gaps between protuberances 103a etc. and yokes 104a etc. as shown in Fig 3. Referring to Fig 3, an axial cross section view is shown for a rotor angular position such that the protuberance 103a is in the opening of the U-shaped yoke 104a. As can be seen, two thin radial air-gaps 306a and 306b are created.

When a current is run in the coil 105a, a magnetic flux runs in the yoke 104a on a closed path as indicated by dotted line 307. This magnetic flux creates an attraction force between the yoke 104a and the rotor-phase protuberance 103 a. The radial components of these two forces at air-gaps 306a and 306b are of opposite direction, so that the total radial force applied on the protuberance 103a is null or very small.

If the angular position of the shaft is such that the protuberance 103a is not fully inserted in the yoke, then a tangential force is applied at air-gaps 306a and 306b, thus producing a rotational torque on the rotor-phase. The angular distribution of the protuberances 103a etc. and the yokes 104a etc. around the shaft are designed to produce an angular periodically varying torque on the rotor-phase. In an embodiment, the number of Yokes and protuberance are equal, and the Yokes and protuberances are equally distributed around the shaft. In that case, the torque produced by a given current will be periodic over a period having an angular frequency equal to the number of yokes.

For the purpose of reducing the torque variation with rotation angle, the motor may be designed to have a different number of yokes and protuberances, and yokes and/or protuberances need not be evenly distributed.

The shape of the protuberance 103a- 103c may be designed to optimize the periodic torque function of rotation angle, in order to minimize the torque variation with rotation angle. This shaping of the protuberance introduces airgaps and torque varying with the rotor rotation optimally so that a current controller may operate the motor with a minimum of torque variation with rotation angle.

The motor-phase of the present embodiments is thus able to produce a torque without inducing radial force and stress on the rotor-phase cup.

A motor controller may be used to coordinate and control the currents in the three coils 105a, 105b, 105c in order to generate the desired torque on the motor shaft.

Advantages of the present motor may include the forces applied on the rotor being at minima, due to the balancing of the air-gap forces, thus avoiding vibrations and mechanical resonances.

Furthermore, the rotor may be made of thinner material, thus reducing the rotor inertia. Another advantage of a motor according to the present embodiment is that for a given coil and motor size the number of yokes (104a etc.) and protuberances (103a etc.) may be increased up to the optimum value giving a maximum of torque, and a motor of the present embodiments may have a higher torque density than other motors of the same size.

Yet another advantage of this motor is its simple construction. The number of coils is small, typically one per phase instead of 1 coil per each rotor salient pole of common switched reluctance motors.

Referring to Fig 4a a switched reluctance motor according to a further embodiment of the present invention is shown where two rotor-phases are joined in one component. Shown in Fig 4a is a three-phase motor of the present embodiment where the yokes of the middle phase (like 404b) are oriented in an opposite axial direction. This allows the joining of two rotor phases (as with 102b and 102c of Fig 1) into one double rotor-phase 402bc shown separately in Fig 4b. This allows a reduction in the part numbers of the motor. Furthermore, yokes for two phases like 404a and 404b can be built in one piece, thus reducing the number of parts of the motor.

In the above-described embodiments, the yokes are shown as separate components. This is applicable for example if the yokes are made of electrical steel laminations. In other embodiments, it is possible to join all the yokes of one or two phases in one part made of bulk material, for example magnetic composite material, or machined material.

Referring now to Fig 5a, a yoke 500 is shown implementing in one piece eight yokes similar to part 104a of Fig 1, as a continuous ring part. The yoke 500 is made of magnetic material such as a composite. In Fig 5b is shown a yoke 501 implementing in one piece 16 yokes, 8 yokes similar to part 404a and 8 yokes similar to part 404b, both of Fig 4a, again built as a continuous ring part.

The yoke implementation in one piece as 500 or 501 may drastically simplify the motor assembly and cost.

Having described in detail embodiments of the present invention for rotary motors, we will describe below implementations for linear motors according to the same principle.

Fig 6a shows a first embodiment of a linear motor. A long and straight toothed bar 602 is made of magnetic material, such as iron, electrical steel laminations or composite material and is fixed on a base plate 601. Three yokes 604a, 604b and 604c have openings to receive the toothed bar and may slide along the bar by means of linear bearings (not shown). Each yoke (604a, 604b and 604c) is surrounded at its upper part by a wound coil (605a, 605b, 605c). The three yokes and coils are fixed together to a mover part (not shown) and form a carriage. In fig 6b it is shown that the yokes are toothed at the internal sides of their opening (606). The internal teeth of the yokes have exactly the same pitch as the teeth of the toothed bar 602. When the teeth 603 of the toothed bar are aligned with the teeth 606 of the yokes (604a or 604b or 604c) two thin air-gaps remain on both side of the toothed bar. Whenever a current is run in coil 605a, a magnetic flux is generated on a close path illustrated by the dotted line 607, and two attraction forces are generated at the air- gaps between the toothed bar and the yoke 604a, tending to align the teeth of the toothed bar 602 with the teeth of the yoke 604a. The transverse components of these two forces are of opposite transverse direction and cancel each other. The longitudinal components of these forces cooperate to produce a thrust. The distance between yokes is designed so that by controlling the current intensity in each coil, it is possible to control the total thrust applied on the carriage. In the embodiment shown here in Fig 6a, the distance between yokes, or phase, is set so that if yoke 604a has teeth aligned with the toothed bar, then yoke 604b is distant by l/3 ^rd of the pitch from the alignment, and 604c is distant 2/3 ^rd of the pitch from the alignment.

A motor controller may then control the current in each of the 3 coils 605a, 605b and 605c to produce the desirable thrust and movement of the carriage. This is obtained without producing transverse force, thus avoiding vibrations and noise.

Referring to Fig 7, an implementation of a linear motor of the present embodiments includes three parallel toothed bars (706a, 706b and 706c). Three yokes 704a, 704b and 704c are fixed together with a moving part (not shown) and form a carriage that can slide on a path parallel to the toothed bars. The yokes 704a, 704b and 704c have a similar shape to yokes 604a, 604b and 604c of Fig 6, and coils 705a, 705b and 705c surround their upper part. A motor controller may control the current in the three coils and generate thrust and sliding of the carriage, exactly in the same way as for the previous implementation shown in Figs 6a and 6b, without generating transverse forces, thus avoiding vibrations and noise.

Both linear motor implementations shown above, referring to Figs 6a to 7 have static toothed bars and moving yokes and coils, and may require moving cables to connect the coils to a motion controller.

In another implementation, shown in Fig 8a, the need for moving cables is avoided and the weight of the carriage is reduced.

Referring to Fig 8a, a large number of static yokes are similar to the yokes described above, see part 504a in Fig 5). Static yokes 804aa-804dc are fixedly disposed on a linear path. The yokes are distributed along the length in adjacent groups of 3 yokes per group. In Fig 8a four groups 841- 844 are shown. A toothed bar 802 (Fig 8b) is fixed to a carriage 803 and travels linearly inside the openings of the yokes 804aa-804dc by means of linear bearings (not shown). The length of the toothed bar 802 is at least the length defined by a group of three yokes. The relative linear positions between yokes of one group are set with a phase difference as described above, referring to the implementation illustrated in Fig 6a. Many motion controllers may then be used to run currents in the coils surrounding the yokes receiving a portion of the toothed bar 802 in their openings, and coordinate the amplitude of the currents to generate the desired force and movement of the carriage. Twelve yokes in four groups are shown in Fig 8a, however it should be understood that an arbitrary number of yokes may be used to implement an arbitrary path length for the linear motor.

The linear path may be straight, but may alternatively be curvilinear, open or closed and of any other shape. For example the yokes may be oriented horizontally in order to allow curvature of the path in the horizontal plane while maintaining a minimum air-gap between the toothed bar and yokes.

Many variations, parameters and implementations may be considered in the scope of this invention, for both rotary and linear implementations. For example:

• Various number of phases and phase difference, for optimization of torque or force ripple versus a cost increase;

• Shape of teeth: to optimize ripple at the extent of reducing the maximum torque of force;

Motor implementations described above apply whenever the motor is generating mechanical power (motor mode) or is generating electrical power (generator mode).

While being used in a particular application, the motor may be in motor mode, in generator mode or alternatively a changing mode may be provided in which the motor alternates between generating and driving, for example in a motor that provides electromagnetic braking.

Advantageous characteristics of the above-described implementations are:

• Magnetic flux run in an axial plane and which traverses the air-gap radially;

• Transverse components of attraction forces substantially annihilate each other;

• Each coil traverses a (large) number of yokes, and the number of yokes is not limited by the coil.

The present embodiments may provide a switched reluctance motor phase including:

• One or more yokes of magnetizable material with a two-sided opening to receive a) a portion of a wound coil traversing it and b) a portion of a toothed part, the toothed part being of cylindric or linear shape,

• wherein the yoke opening is also toothed inward on both side areas facing the toothed cylindric or linear bar;

• wherein when the toothed path traversing the yoke opens an air-gap of variable size; • and wherein electric current run in the coil generates two attraction forces between the yoke and the cylindrical or linear bar, at the air gaps, tending to align the teeth of the yoke opening with the teeth of the said toothed part;

• wherein the transverse components of the attraction force substantially annihilate or cancel each other so that minimal transverse forces are applied on the toothed part.

Herein the term “substantially” means that the forces are cancelled to an extent that meaningfully reduces vibrations or noise.

It is expected that during the life of a patent maturing from this application many relevant improvements to switched reluctance electrical motors and their windings will be developed and the scopes of these and other terms herein are intended to include all new technologies a priori.

The terms "comprises", "comprising", "includes", "including", “having” and their conjugates mean "including but not limited to".

The term “consisting of’ means “including and limited to”.

As used herein, the singular form "a", "an" and "the" include plural references unless the context clearly dictates otherwise.

It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment and the present description is to be construed as if such embodiments are explicitly set forth herein. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination or may be suitable as a modification for any other described embodiment of the invention and the present description is to be construed as if such separate embodiments, subcombinations and modified embodiments are explicitly set forth herein. Certain features described in the context of various embodiments are not to be considered essential features of those embodiments, unless the embodiment is inoperative without those elements.

Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.

All publications, patents and patent applications mentioned in this specification are herein incorporated in their entirety by reference into the specification, to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated herein by reference. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present invention. To the extent that section headings are used, they should not be construed as necessarily limiting. In addition, any priority document(s) of this application is/are hereby incorporated herein by reference in its/their entirety.