CN218386990U - Magnetic line of force skew formula motor and electric screwdriver - Google Patents

Abstract

The utility model relates to an electric screwdriver technical field especially relates to a magnetic line of force skew formula motor, include: a stator and a rotor. The stator includes: the iron core and the enameled wire wound on the iron core. The iron core is provided with a plurality of wire grooves arranged along the axial direction. The rotor includes: the magnetic ring comprises a rotating shaft and a plurality of magnetic rings. The rotating shaft is arranged along the central shaft of the iron core. The plurality of magnetic rings are sequentially connected on the rotating shaft in series along the axial direction of the rotating shaft. And a marking line for marking the direction of the magnetic force line is arranged on the outer side of each magnetic ring. The mark lines of two adjacent magnetic rings are staggered, and the mark lines of two spaced magnetic rings are positioned on the same straight line. The application also provides an electric screwdriver. The magnetic lines of force of each magnetic ring are marked by the marking lines, the plurality of magnetic rings are connected in series by the marking lines to form the magnet group with the magnetic lines of force in a regular reciprocating offset state, the purpose of weakening the magnetic slot effect is achieved, the magnetic slot effect can be realized only by slightly modifying and upgrading the traditional structure, the structure is simple, the process difficulty is small, and the manufacturing cost is low.

Description

Magnetic line of force skew formula motor and electric screwdriver

Technical Field

The utility model relates to an electric screwdriver technical field especially relates to a magnetic force line skew formula motor, an electric screwdriver including this magnetic force line skew formula motor.

Background

The electric screwdriver is an electric screw tightening tool, is widely applied to industry and daily life, and can enable the screw to be simply and efficiently disassembled and assembled, thereby saving time and labor. The power source of the electric screwdriver is a motor, and the motor drives a tightening shaft (or a screwdriver head) to rotate so as to rotate a screw. At present, most of motors applied to the electric screw driver are slot type motors. The slot type motor is characterized in that a plurality of slots arranged along the axial direction are arranged on the inner wall of an iron core of a stator, and an enameled wire is wound at the slots. The rotor is arranged at the central shaft of the stator in a penetrating mode. The rotor generally includes a rotating shaft and a magnet mounted on the rotating shaft.

In early designs, a slot-type motor rotor was constructed by axially fixing a plurality of magnetic rings (typically annular neodymium-iron-boron magnets, also known as quadrupole radial ring magnets) in series on a rotating shaft. However, the disadvantage of this design is that when the magnetic rings are connected in series, the magnetic rings will automatically adjust their posture under the action of the magnetic force between adjacent magnetic rings to form a magnet set with magnetic lines on the same straight line, and when the motor rotates at low speed, an obvious magnetic slot effect will occur, so that when the rotor crosses the magnetic slot, the rotor will shake, thereby destroying the stability of the motor when it runs at low speed.

In order to weaken the magnetic slot effect of the motor, two main solutions are available in the industry at present. The first solution is: the structure of the magnetic slot of the stator is modified, the magnetic slot is modified into an inclined design which forms a certain included angle with the axial direction, so that the magnetic slot and the magnetic line of force of the magnet group form a certain included angle, and the purpose of weakening the magnetic slot effect is achieved. The second solution is: the split of the magnetic ring is divided into a plurality of arc magnets, and the accommodating grooves (fixing structures) for fixing the arc magnets are additionally arranged on the rotating shaft, so that the plurality of arc magnets form a magnet group in a staggered arrangement mode, the purpose of weakening the effect of the magnetic grooves is achieved, the defect that the arc magnets and the accommodating grooves in specific shapes need to be manufactured is overcome, the structural complexity of the rotor is greatly increased, and the problems of high process difficulty and high manufacturing cost exist.

SUMMERY OF THE UTILITY MODEL

Based on this, the utility model provides a magnetic force line skew formula motor improves the rotor, utilizes the marking line to mark the magnetic force line of every magnetic ring, makes a plurality of magnetic rings concatenate the magnet group who forms the state that the magnetic force line presents regular reciprocal skew with the help of the marking line, reaches the purpose that weakens the magnetic channel effect, only needs to carry out the transformation upgrading of small range to traditional structure alright realize, simple structure, and the technology degree of difficulty is little, and the cost of manufacture is low.

A flux offset motor comprising:

a stator; the stator includes: the iron core and the enameled wire wound on the iron core; the iron core is provided with a plurality of wire grooves arranged along the axial direction of the iron core; the enameled wire is positioned in the wire slot; and

a rotor mounted on the stator; the rotor includes: the magnetic ring is arranged on the rotating shaft; the rotating shaft is arranged along the central shaft of the iron core; the plurality of magnetic rings are sequentially connected on the rotating shaft in series along the axial direction of the rotating shaft; the outer side of each magnetic ring is provided with a marking line for marking the direction of the magnetic force line; the mark lines of two adjacent magnetic rings are staggered, and the mark lines of two spaced magnetic rings are positioned on the same straight line.

The rotor of the magnetic line offset motor is designed in a magnetic line offset mode, and a plurality of magnetic rings are sequentially connected in series along the axial direction of the rotating shaft to form a magnet group. The magnetic lines of force are marked on each magnetic ring by using the marking lines, so that the positions of the magnetic lines of force of the magnetic rings can be accurately adjusted during installation. When the rotor is assembled, the marking lines of two adjacent magnetic rings are staggered, and the marking lines of two spaced magnetic rings are positioned on the same straight line, so that the magnetic force lines of a magnet group formed by a plurality of magnetic rings are in a regular reciprocating offset state, and when the rotor rotates and passes through the wire grooves of the iron core, the purpose of weakening the magnetic groove effect is achieved by utilizing the design of the reciprocating offset of the magnetic force lines. Through the design, the rotor is improved, the magnetic lines of force of each magnetic ring are marked by the marking lines, the plurality of magnetic rings are connected in series by the marking lines to form the magnet group with the magnetic lines of force in a regular reciprocating offset state, the purpose of weakening the magnetic slot effect is achieved, the improvement and the upgrade of the traditional structure can be realized only by a small range, the structure is simple, the process difficulty is small, and the manufacturing cost is low.

In one embodiment, a glue layer is arranged between the inner side wall of each magnetic ring and the outer side wall of the rotating shaft so as to realize bonding fixation. When the magnetic rings are connected in series, the adjacent magnetic rings are bonded and fixed through the glue layer, so that the mark line of each magnetic ring can be accurately stopped at a preset position, the glue bonding mode does not need to structurally change the magnetic rings and the rotating shaft, the cost is low, and the feasibility is high.

In one embodiment, two adjacent magnetic rings are fixedly connected through welding. The magnetic ring is fixed on the rotating shaft in a preset posture in a welding mode, and the structure is stable.

In one embodiment, the rotating shaft is fixedly connected with each magnetic ring through a concave-convex structure. The concave-convex structures which can be matched with each other are respectively arranged on the rotating shaft and the magnetic rings, so that each magnetic ring can be fixed on the rotating shaft according to a preset posture, the structure is stable, and the installation is convenient.

In one embodiment, the dislocation distance of the marking lines of two adjacent magnetic rings along the circumferential direction is d, and d is more than or equal to 1.5mm and less than or equal to 2.0mm.

In one embodiment, the rotor further comprises: the dynamic balance block is sleeved on the rotating shaft. The dynamic balance block is used for adjusting a balance weight structure of the rotating shaft, and the balance of the rotor is improved when the rotor rotates at a high speed.

In one embodiment, the magnetic flux offset motor further includes: the stator protection shell is accommodated in the stator, and the heat dissipation fan blade is positioned in the protection shell; an air inlet is formed in the side wall of one end of the protective shell; an air outlet is formed in the side wall of the other end of the protective shell; the air inlet, the wire groove and the air outlet are communicated in sequence to form a flow channel for air to flow; the heat dissipation fan blade is sleeved on the rotor to rotate along with the rotor, and is located at one end of the stator and adjacent to the air outlet. The heat dissipation fan blade rotates along with the rotor, so that air at the air outlet is discharged to form negative pressure, external air flows through the wire groove from the air inlet along the flow channel and is discharged from the air outlet, heat is taken away by utilizing flowing air to achieve the purpose of heat dissipation and cooling, and the service life of the equipment is prolonged.

In one embodiment, the air outlet comprises a plurality of air outlet holes which are uniformly distributed on the protective shell along the circumferential direction; the air inlet comprises a plurality of air inlets which are uniformly distributed on the protective shell along the circumferential direction. The air outlet holes and the air inlet holes are circumferentially and uniformly distributed on the protective shell, so that outside air can enter the flow channel from the periphery of one end of the protective shell and is discharged from the periphery of the other end of the protective shell, and the heat dissipation efficiency is high.

In one embodiment, the magnetic flux offset motor further includes: an encoder connected to the rotor; the encoder is connected with the rotating shaft and is located at one end of the protective shell. The encoder is used for detecting the rotation condition of the rotor, and is convenient for monitoring the operation condition of the rotor.

Simultaneously, this application still provides an electric screwdriver.

An electric screwdriver comprising: the magnetic line of force offset type motor of any of the above embodiments.

The electric screwdriver is provided with a magnetic line offset motor. In the magnetic force line offset type motor, a rotor is improved, the magnetic force lines of each magnetic ring are marked by using the marking lines, a plurality of magnetic rings are connected in series by means of the marking lines to form a magnet group with the magnetic force lines in a regular reciprocating offset state, the purpose of weakening the magnetic slot effect is achieved, the magnetic slot offset type motor can be realized only by carrying out small-amplitude transformation and upgrade on the traditional structure, and the magnetic slot offset type motor is simple in structure, small in process difficulty and low in manufacturing cost.

Drawings

Fig. 1 is a perspective view of a magnetic line of force offset motor according to an embodiment of the present invention;

fig. 2 is an axial sectional view of the magnetic flux offset motor shown in fig. 1;

fig. 3 is an exploded view of the flux-offset motor shown in fig. 2;

fig. 4 is a schematic view of a stator in the magnetic flux offset motor shown in fig. 3;

fig. 5 is a schematic view of the core in the stator shown in fig. 4;

fig. 6 is a schematic view of a rotor in the magnetic flux offset motor shown in fig. 3;

fig. 7 is an enlarged view of a portion a of the rotor shown in fig. 6.

The meaning of the reference symbols in the drawings is:

100-magnetic line offset type motor;

10-stator, 11-iron core, 111-wire casing, 12-insulating part;

20-rotor, 21-rotating shaft, 22-magnetic ring, 221-marking line and 23-dynamic balance block;

30-protective shell, 31-air inlet, 311-air inlet, 32-air outlet and 321-air outlet;

40-heat dissipation fan blades;

and 50, an encoder.

Detailed Description

In order to make the above objects, features and advantages of the present invention more comprehensible, embodiments of the present invention are described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. The invention may be embodied in many other forms different from those described herein and similar modifications may be made by those skilled in the art without departing from the spirit and scope of the invention and, therefore, the invention is not to be limited to the specific embodiments disclosed below.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", and the like, indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore, should not be construed as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or to implicitly indicate the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," and "fixed" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meaning of the above terms in the present invention can be understood according to specific situations by those skilled in the art.

In the present application, unless expressly stated or limited otherwise, the first feature may be directly on or directly under the second feature or indirectly via intermediate members. Also, a first feature "on," "above," and "over" a second feature may be directly on or obliquely above the second feature, or simply mean that the first feature is at a higher level than the second feature. A first feature "under," "beneath," and "under" a second feature may be directly under or obliquely under the second feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like as used herein are for illustrative purposes only and do not denote a unique embodiment.

As shown in fig. 1 to 7, a magnetic line offset motor 100 according to an embodiment of the present invention is provided.

As shown in fig. 1 to 3, the magnetic flux offset motor 100 includes: a stator 10 and a rotor 20 mounted on the stator 10. When the rotor is in work, the stator 10 generates a magnetic field after being electrified so as to force the rotor 20 to rotate, wherein the rotor 20 is designed in a magnetic line offset mode, the magnetic slot effect is weakened, and the stability of the rotor 20 in low-speed rotation is improved.

The magnetic flux offset motor 100 will be further described with reference to fig. 1 to 7.

As shown in fig. 2, 4 and 5, the stator 10 includes: an iron core 11 and an enamel wire (not shown) wound around the iron core 11. As shown in fig. 5, the core 11 is provided with a plurality of slots 111 arranged in the axial direction of the core 11. The enamel wire is located in the wire chase 111. As shown in fig. 5, in the present embodiment, the core 11 is provided with 6 slots 111 arranged in the axial direction, and is provided in a six-slot structure.

Further, as shown in fig. 2 and 4, in the present embodiment, the stator 10 further includes: and insulators 12 at both ends of the core 11.

As shown in fig. 2 and 6, the rotor 20 includes: a rotating shaft 21 passing through the iron core 11 and a plurality of magnetic rings 22 mounted on the rotating shaft 21. The rotating shaft 21 is disposed along the central axis of the iron core 11, and the plurality of magnetic rings 22 are serially connected to the rotating shaft 21 along the axial direction of the rotating shaft 21. The outer side of each magnetic ring 22 is provided with a marking line 221 for marking the direction of the magnetic force lines. The mark lines 221 of two adjacent magnetic rings 22 are staggered, and the mark lines 221 of two spaced magnetic rings 22 are located on the same straight line. For example, as shown in fig. 6, in the present embodiment, 5 magnetic rings 22 are serially connected to the rotating shaft 21 in sequence.

When the magnetic rings 22 are connected in series with the rotating shaft 21 in sequence, the magnetic rings 22 will automatically adjust their postures under the action of magnetic force if no other acting force is applied, so that the magnetic lines of force of the magnet groups formed by the series connection will present a straight line. Therefore, when the magnetic ring 22 is installed, a corresponding fixing structure needs to be arranged, and various realizable modes exist.

For example, in the present embodiment, a glue layer (not shown) is disposed between an inner sidewall of each magnetic ring 22 and an outer sidewall of the rotating shaft 21 to achieve adhesion fixation. When the magnetic rings 22 are connected in series, the magnetic rings 22 and the rotating shaft 21 are bonded and fixed through the glue layers between the adjacent magnetic rings 22, so that the mark line 221 of each magnetic ring 22 can accurately stay at the preset position, the glue bonding mode does not need to change the structures of the magnetic rings 22 and the rotating shaft 21, the cost is low, and the feasibility is strong. For example, when the magnetic rings 22 are connected in series, the first magnetic ring 22 is sleeved in the rotating shaft 21 and moved to a predetermined position, the magnetic rings 22 are rotated to make the mark line 221 reach the predetermined position, glue is applied and pressure is maintained (auxiliary pressure maintaining can be performed through a jig), after the glue is cured, the next magnetic ring 22 is connected in series, and the process is repeated until all the magnetic rings 22 are completely installed.

For another example, two adjacent magnetic rings 22 are fixedly connected by welding. The magnetic ring 22 is fixed on the rotating shaft 21 in a preset posture by welding, and the structure is stable. For example, after the magnetic rings 22 are connected in series (or spliced) in a preset posture, the magnetic rings 22 are fixed by laser welding.

For another example, the shaft 21 and each magnetic ring 22 are fixedly connected by a concave-convex structure. The concave-convex structures which can be matched with each other are respectively arranged on the rotating shaft 21 and the magnetic rings 22, so that each magnetic ring 22 can be fixed on the rotating shaft 21 according to a preset posture, the structure is stable, and the installation is convenient. For example, a convex strip is disposed on the inner wall of each magnetic ring 22, and a groove (two grooves may be disposed corresponding to the installation positions of the magnetic rings 22 in different postures) is disposed on the outer side wall of the rotating shaft 21, so that the magnetic rings 22 may be sequentially disposed on the rotating shaft 21 along the corresponding grooves according to the respective preset postures.

As shown in FIG. 7, in the present embodiment, the offset distance of the mark lines 221 of two adjacent magnetic rings 22 along the circumferential direction is d, and d is greater than or equal to 1.5mm and less than or equal to 2.0mm.

Further, as shown in fig. 2 and 6, in the present embodiment, the rotor 20 further includes: a dynamic balance weight 23 sleeved on the rotating shaft 21. The dynamic balance weight 23 is used for adjusting the balance structure of the rotating shaft 21, and improves the balance of the rotor 20 during high-speed rotation. In the present embodiment, the number of the dynamic balance weight 23 is two, one of which is disposed at one end of the rotation shaft 21, and the other of which is disposed at the other end of the rotation shaft 21.

As shown in fig. 1 to fig. 3, in the present embodiment, the magnetic flux offset motor 100 further includes: the stator protection structure comprises a protection shell 30 for accommodating the stator 10 and heat dissipation fan blades 40 positioned in the protection shell 30. An air inlet 31 is formed in a sidewall of one end of the protective case 30, and an air outlet 32 is formed in a sidewall of the other end of the protective case 30. The inlet port 31, the wire duct 111, and the outlet port 32 are sequentially communicated to form a flow passage through which gas flows. The heat dissipation fan blade 40 is sleeved on the rotor 20 to rotate along with the rotor 20, and the heat dissipation fan blade 40 is located at one end of the stator 10 and is adjacent to the air outlet 32. The heat dissipation fan blade 40 rotates along with the rotor 20, so that air at the air outlet 32 is discharged to form negative pressure, external air flows through the wire slot 111 from the air inlet 31 along the flow channel and is discharged from the air outlet 32, heat is taken away by utilizing flowing air to achieve the purpose of heat dissipation and cooling, and the service life of the equipment is prolonged.

Further, as shown in fig. 3, the air outlet 32 includes a plurality of air outlet holes 321 uniformly distributed on the protective shell 30 along the circumferential direction. The air inlet 31 includes a plurality of air inlet holes 311 uniformly distributed on the protective case 30 in the circumferential direction. The air outlets 321 and the air inlets 311 are circumferentially and uniformly distributed on the protective shell 30, so that external air can enter the flow channel from the periphery of one end of the protective shell 30 and then be discharged from the periphery of the other end of the protective shell 30, and the heat dissipation efficiency is high.

In addition, as shown in fig. 1 to 3, the magnetic flux offset motor 100 further includes: an encoder 50 connected to the rotor 20. The encoder 50 is connected to the rotating shaft 21 and located at one end of the protective casing 30. The encoder 50 is used to detect the rotation of the rotor 20, so as to monitor the operation of the rotor 20. In the present embodiment, the encoder 50 is a magnetic encoder 50.

The working principle is explained as follows:

the rotor 20 of the magnetic offset motor is designed in a magnetic line offset manner, as shown in fig. 6, a plurality of magnetic rings 22 are sequentially connected in series along the axial direction of the rotating shaft 21 to form a magnet set. The magnetic lines of force are marked on each magnetic ring 22 by using a marking line 221, so that the position of the magnetic lines of force of the magnetic ring 22 can be accurately adjusted during installation. When the rotor 20 is assembled, the mark lines 221 of two adjacent magnetic rings 22 are dislocated, and the mark lines 221 of two spaced magnetic rings 22 are located on the same straight line, so that the magnetic lines of force of the magnet group formed by the plurality of magnetic rings 22 are in a regular reciprocating offset state, and when the rotor 20 rotates and passes through the slot 111 of the iron core 11, the purpose of weakening the magnetic slot effect is achieved by utilizing the design of the reciprocating offset of the magnetic lines of force.

The magnetic line of force skew formula motor 100 improves rotor 20, utilizes mark line 221 to mark the magnetic line of force of every magnetic ring 22, makes a plurality of magnetic rings 22 concatenate to form the magnet group that the magnetic line of force appears the state of regular reciprocal skew with the help of mark line 221, reaches the purpose that weakens the magnetic groove effect, only needs to carry out the transformation upgrade of small extent to traditional structure and can realize, simple structure, and the technology degree of difficulty is little, and the cost of manufacture is low.

Simultaneously, this application still provides an electric screwdriver.

This electric screwdriver includes: the magnetic flux offset motor 100 of the above embodiment.

The electric screwdriver is provided with a magnetic line offset type motor 100. In the magnetic force line offset type motor 100, the rotor 20 is improved, the magnetic force lines of each magnetic ring 22 are marked by the marking lines 221, the plurality of magnetic rings 22 are connected in series by the marking lines 221 to form a magnet group with the magnetic force lines in a regular reciprocating offset state, the purpose of weakening the magnetic slot effect is achieved, the magnetic slot effect can be realized only by slightly modifying and upgrading the traditional structure, the structure is simple, the process difficulty is small, and the manufacturing cost is low.

The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above examples only represent preferred embodiments of the present invention, which are described in more detail and detail, but are not to be construed as limiting the scope of the invention. It should be noted that, for those skilled in the art, without departing from the concept of the present invention, several variations and modifications can be made, which all fall within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.

Claims (10)

1. A magnetic flux offset motor, comprising:

a stator; the stator includes: the iron core and the enameled wire wound on the iron core; the iron core is provided with a plurality of wire grooves arranged along the axial direction of the iron core; the enameled wire is positioned in the wire slot; and

a rotor mounted on the stator; the rotor includes: the magnetic ring is arranged on the rotating shaft in a penetrating way; the rotating shaft is arranged along the central shaft of the iron core; the plurality of magnetic rings are sequentially connected on the rotating shaft in series along the axial direction of the rotating shaft; the outer side of each magnetic ring is provided with a marking line for marking the direction of the magnetic force line; the mark lines of two adjacent magnetic rings are staggered, and the mark lines of two spaced magnetic rings are positioned on the same straight line.

2. The magnetic force line offset motor of claim 1, wherein a glue layer is disposed between the inner sidewall of each magnetic ring and the outer sidewall of the rotating shaft to achieve adhesion fixation.

3. The magnetic force line offset motor according to claim 1, wherein two adjacent magnetic rings are fixedly connected by welding.

4. The magnetic force line offset motor according to claim 1, wherein the rotating shaft is fixedly connected to each of the magnetic rings through a concave-convex structure.

5. The magnetic force line offset motor as claimed in claim 1, wherein the offset distance of the mark lines of two adjacent magnetic rings along the circumferential direction is d, and d is greater than or equal to 1.5mm and less than or equal to 2.0mm.

6. The offset flux machine of claim 1, wherein the rotor further comprises: and the dynamic balance block is sleeved on the rotating shaft.

7. The offset flux machine of claim 1, further comprising: the stator comprises a protective shell for accommodating the stator and a heat dissipation fan blade positioned in the protective shell; an air inlet is formed in the side wall of one end of the protective shell; an air outlet is formed in the side wall of the other end of the protective shell; the air inlet, the wire groove and the air outlet are communicated in sequence to form a flow channel for gas to flow; the heat dissipation fan blade is sleeved on the rotor to rotate along with the rotor, and is located at one end of the stator and adjacent to the air outlet.

8. The magnetic force line offset motor as claimed in claim 7, wherein the air outlet includes a plurality of air outlets evenly distributed on the protective casing along the circumferential direction; the air inlet comprises a plurality of air inlets which are uniformly distributed on the protective shell along the circumferential direction.

9. The flux-offset electric machine of claim 7, further comprising: an encoder connected to the rotor; the encoder is connected the pivot just is located the one end of protective housing.

10. An electric screwdriver, comprising: the flux-offset electric machine of any one of claims 1 to 9.

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