Fastening of axial flux motor stator
By using lugs and fastening elements in the fastening device of the axial flux electric motor, the problems of housing sealing and increased weight caused by stator fastening are solved, achieving stable installation and weight control.
Patent Information
- Application Number
- CN202380042040.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-05-23
- Filing Date
- 2023-05-23
- Publication Date
- 2025-01-07
AI Technical Summary
In existing axial flux electric motors, the stator fastening methods have problems with housing sealing and increased motor weight, especially the screw and rod fastening methods, which result in poor sealing and increased weight.
The fastening device includes lugs that protrude radially from the stator yoke and fastening elements. The lugs interact with the housing to achieve internal fixation of the stator, avoid housing sealing problems, and limit the increase in motor weight.
This design achieves a stable installation of the stator, avoids housing sealing issues, limits the increase in motor weight, and simplifies the disassembly process.
Smart Images
Figure CN119278565A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of electric motors, and in particular to a stator for securing an axial flux electric motor. Background Art
[0002] A radial flux synchronous electric motor generally comprises a rotor rotatably mounted inside a stator, which is fastened to the housing by shrink fit or by means of screws passing through the housing. The stator generally comprises a laminated core forming a yoke and a plurality of teeth extending radially around the axis of rotation of the rotor, on which windings are wound which are capable of interacting with permanent magnets carried by the rotor to rotate said rotor.
[0003] In an axial flux electric motor, the rotor does not extend inside the stator, but is sandwiched between two stators extending symmetrically on either side of the rotor. The laminated core of each stator then forms axially extending teeth, around which the windings that interact with the permanent magnets of the rotor are wound. Shrink fitting of the stator is not possible.
[0004] One solution involves screwing the stator to the motor housing by means of screws that pass through the housing. However, tightening the stator in this way creates problems, in particular with regard to housing sealing, and involves tapping or adding inserts in the stator yoke, which can cause the laminated core forming the stator yoke to separate.
[0005] Another solution involves tightening a rod extending radially between two teeth. However, tightening the stator in this way requires the following special features:
[0006] - the height of the teeth must be increased to limit the magnetic imbalance created by the rods; this increases the mass of the stator and therefore the mass of the motor;
[0007] - the bars must be put in place before winding to limit degradation and impregnation of the windings, which complicates the removal of said bars; and
[0008] - The screws for tightening the rods must be placed far enough from the windings to limit dielectric problems and difficulties in passing through the windings, which increases the mass of the stator and therefore of the motor. Summary of the invention
[0009] The object of the present invention is therefore to propose a device for fastening a stator of an axial flux electric motor which overcomes at least some of the above-mentioned drawbacks.
[0010] To this end, an electric motor is proposed, which comprises a housing, inside which at least one stator and a rotor rotatable about an axis relative to the stator are mounted, the rotor having magnetic poles, and the stator comprising a ferromagnetic yoke portion carrying windings, which are arranged to generate an axial flux electric motor together with the magnetic poles of the rotor.
[0011] According to the invention, the stator is fixed in position relative to the housing by means of fastening means comprising lugs protruding radially from the surface of the yoke, and at least one fastening element fastened to the housing and arranged to interact with the lugs to lock the stator along and around the axis.
[0012] This fastening arrangement allows the stator to be assembled from the inside without causing any casing sealing problems, while limiting the weight of the motor.
[0013] Specifically, the lugs protrude from the inner surface of the yoke.
[0014] Specifically, the motor includes a pin inserted into a hole made in the yoke, with the end of the pin radially protruding from the surface of the yoke to form a lug.
[0015] In particular, the lugs are evenly angularly distributed around the axis.
[0016] Specifically, the yoke of the stator is generally annular and includes a plurality of teeth around which the windings are wound and from which the lugs extend.
[0017] According to a particular embodiment, the fastening means comprises a single fastening element comprising a flange comprising a plate provided with bayonet fastening recesses adapted to receive the lugs.
[0018] In particular, the plate comprises an outer cylindrical bearing surface arranged to interact with a corresponding bearing surface formed by the inner surface of the stator.
[0019] According to another particular embodiment, the fastening device comprises a plurality of fastening elements, each fastening element comprising a screw which passes through the housing and is screwed into a thread arranged along the axis in one of the lugs.
[0020] Specifically, the motor includes two identical stators extending symmetrically on both sides of the rotor.
[0021] The invention also relates to an aircraft comprising at least one landing gear comprising a strut mounted on the aircraft structure so as to be pivotable between a deployed position and a retracted position by means of an electric motor of the above-described type. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The invention will be better understood from the following description, which is purely illustrative and not restrictive and should be read with reference to the accompanying drawings, in which:
[0023] [ Figure 1 ] Figure 1 is a schematic diagram of an aircraft provided with an electric motor according to a specific embodiment of the present invention;
[0024] [ Figure 2 ] Figure 2 yes Figure 1 An exploded view of the electric motor shown in ;
[0025] [ Figure 3 ] Figure 3 yes Figure 2 A perspective view of a rotor of an electric motor;
[0026] [ Figure 4A ] Figure 4A yes Figure 2 A perspective view of one of the stators of the electric motor shown, without windings;
[0027] [ Figure 4B ] Figure 4B yes Figure 4A A detailed view of the stator is shown, with windings provided;
[0028] [ Figure 5 ] Figure 5 yes Figures 4A to 4B A perspective view of a plate for fastening a stator is shown;
[0029] [ Fig. 6A ] Fig. 6A yes Figure 4A A detail view of the stator is shown with the stator in the inserted position;
[0030] [ Figure 6B ] Figure 6B is with Fig. 6A The same view with the stator in the unlocked position;
[0031] [ Figure 6C ] Figure 6C is with Fig. 6A The same view with the stator in the locked position. DETAILED DESCRIPTION
[0032] refer to Figure 1 The invention is applicable to an aircraft A comprising main landing gears P, each of which comprises a strut J having a first end connected to the structure of the aircraft A so as to be pivotable about an axis Y and a second end carrying a wheel R.
[0033] A first end of the strut J is provided with a gear section D connected thereto so as to be rotatable about an axis Y. The teeth of the gear section D mesh with a pinion, indicated overall by reference 1 , fitted on the output shaft 2 of the electric motor.
[0034] The motor 1 is fastened to the structure of the aircraft and is controlled by a control unit UC in the cockpit K of the aircraft A. The action I controlled by the control unit UC causes the output shaft 2 of the motor 1 and the gear segment D to rotate in a first direction S1 to deploy the landing gear P, or in a second direction S2 to retract the landing gear P. A controllable lock V holds the gear segment D in the deployed or retracted position.
[0035] refer to Figure 2 The motor 1 comprises a housing 10 defining a volume inside which a rotor 20 is mounted extending between a first stator 30a and a second stator 30b. In this example, the housing is made of two parts, a first part 10.1 and a second part 10.2 screwed together.
[0036] The rotor 20 is generally annular and is mounted rotatably about an axis X by means of ball bearings (not shown). Figure 3 As shown, in this example, the rotor 20 is connected to the output shaft 2 of the motor 1 by radial arms 21, so that the rotation of the rotor 20 around the axis X causes the output shaft 2 to rotate around the same axis X. This connection makes it possible to limit the mass of the assembly formed by the rotor 20 and the output shaft 2, which is usually produced in a single piece. The rotor 20 comprises a plurality of permanent magnets 22, which are uniformly angularly distributed around the axis X and whose magnetic poles are alternating. The permanent magnets 22 extend in the radial direction and are made of neodymium in this example.
[0037] The first stator 30a is fastened to the first part 10.1 of the housing 10 by means of the first fastening means 40a, so that the first stator 30a is fixed in position relative to the first part 10.1. Similarly, the second stator 30b is fastened to the second part 10.2 of the housing 10 by means of the second fastening means 40b, so that the second stator 30b is fixed in position relative to the second part 10.2.
[0038] In this example, the first stator 30a and the second stator 30b are identical and extend symmetrically on both sides of the rotor 20. Here, the first fastening means 40a is identical to the second fastening means 40b. Furthermore, only the first stator 30a and the first fastening means 40a will be described.
[0039] like FIG. 4A to FIG. 4BAs shown, the first stator 30a includes a laminated core that forms a ferromagnetic yoke 31 made of soft iron. In this example, the laminated core is generated by winding and is axially arranged. The yoke 31 is generally annular and has a plurality of teeth 32 that extend radially between an inner surface 31.1 and an outer surface 31.2 of the yoke 31, opposite to the permanent magnets 21 of the rotor 20. The inner surface 31.1 and the outer surface 31.2 are cylindrical and define the inner periphery and the outer periphery of the yoke 31, respectively. A coil 33 extends around each tooth 32 and is connected to the control unit UC so as to form an axial flux motor together with the permanent magnets 21 of the rotor 20.
[0040] The first fastening means 40a comprises six pins 41, each of which is force-fitted into a through hole formed in the yoke 31 of the first stator 30. The pins 41 each extend in a radial direction of the yoke 31 and are evenly angularly distributed around the axis X. Each pin 41 comprises a first end 41.1 and a second end 41.2, the first end 41.1 protruding from the inner surface 31.1 of the yoke 31, and the second end 41.2 opposite to the first end 41.1 and protruding from the outer surface 31.2 of the yoke 31. The first end 41.1 and the second end 41.2 form a first lug and a second lug, respectively. In this case, the pins 41 are identical and are generally cylindrical.
[0041] The first fastening device 40a also comprises a plate 42 ( Figure 5 ). The plate 42 is annular and is mounted on the first part 10.1 of the housing 10. To this end, the plate 42 comprises a rear surface that interacts with the bottom of the first part 10.1 of the housing 10 and a first inner cylindrical bearing surface 42.1 that interacts with a corresponding bearing surface arranged in the bottom of said first part 10.1 of the housing 10, so as to center the plate 42 relative to the axis of rotation X of the rotor 20. The plate 42 is screwed to the first part 10.1 of the housing 10 by means of screws passing through holes 42.3 made in the inner periphery of the plate 42, so that said plate 42 is fixed in position relative to said first part 10.1 of the housing 10.
[0042] The plate 42 further comprises a second outer cylindrical bearing surface 42 . 2 extending opposite the inner surface 31 . 1 of the first stator 30 a .
[0043] The plate 42 also comprises six bayonet fastening notches 43 suitable for receiving the first end 41 . 1 of the pin 41 . The notches 43 are arranged on the outer periphery of the plate 42 and are evenly angularly distributed around the axis X. In this case, the notches 43 are identical and comprise:
[0044] a first section 43 . 1 for inserting the first end 41 . 1 of the pin 41 , said first section extending radially from the second cylindrical bearing surface 42 . 2 of the plate 42 ;
[0045] a second section 43.2 for guiding the first end 41.1, said second section being in communication with the first section 43.1 and extending in the circumferential direction while defining a guiding slope; and
[0046] - A third section 43.3, used to fix the first end 41.1 in place, the third section communicating with the second section 43.2 and extending axially from the rear face of the plate 42 to form a groove for receiving the first end 41.1.
[0047] The different steps of fitting the first stator 30a on the first part 10.1 of the housing 10 will now be explained in detail.
[0048] First, the plate 42 is inserted into the first part 10.1 of the housing 10 in the axial direction until the first cylindrical bearing surface 42.1 of the plate 42 interacts with the corresponding bearing surface of the bottom of the first part 10.1 of the housing 10 and the plate 42 bears against the bottom. The plate 42 is then screwed to the first part 10.1 of the housing 10 so that the plate 42 is connected to the first part 10.1 of the housing 10 so as to be rotatable about the axis X while remaining axially movable between an approach position, in which the rear face of the plate 42 bears against the bottom of the first part 10.1 of the housing 10, and a spaced position in which the rear face is at a distance from the bottom.
[0049] Then, the first stator 30a is again inserted in the axial direction into the first part 10.1 of the housing 10, with the teeth 32 of the first stator 32a pointing outwards from the first part 10.1 of the housing 10 and the first ends 41.1 of the pins 41 facing the first section 43.1 of the recess 43 of the plate 42. Since the first ends 41.1 of the pins 41 are received in the first section 43.1 of the recess 43 and the first stator 30a bears against the bottom of the first part 10.1 of the housing 10, the first stator 30a is pivoted by an angle α (equal to 15° in this example) in a predetermined direction suitable for moving the first ends 41.1 of the pins 41 from the first section 43.1 of the recess 43 via the second section 43.2 of the recess 43 to the third section 43.3 of the recess 43, respectively. Due to the action of the first end 41 . 1 of the pin 41 on the slope of the second section 43 . 2 of the recess 43 , the pivoting of the first stator 30 a causes the plate 42 to move from the close position to the spaced position.
[0050] The plate 42 is then tightened with a predefined torque, which moves the plate 42 from the spaced position to the close position and causes the first end 41.1 of the pin 41 to interact with the groove in the third section 43.3 of the recess 43. The first stator 30a is then fixed in place axially and angularly about the axis X by the plate 42, so that it is fixed in place relative to the plate 42 and therefore relative to the first part 10.1 of the housing 10. The plate 42 thus forms a flange.
[0051] Note that arranging the plate 42 in contact with the first stator 30 a in this manner allows the bending of the pin 41 to be restricted.
[0052] Similarly, the second fastening means 40 b comprises a plate 42 adapted to fix the second stator 30 b in position relative to the second part 10 . 2 of the housing 10 .
[0053] It goes without saying that the invention is not limited to the embodiments described, but covers any variant coming within the ambit of the invention as defined by the claims.
[0054] Although the invention is applied here to the main landing gear P of an aircraft A, it can also be applied to any movable landing gear (front landing gear, center landing gear, etc.) installed on the aircraft.
[0055] The number of pins 41 may be less or greater than six. This depends in particular on the axial forces exerted on the stators 30a, 30b via the permanent magnets 21 of the rotor 20 when the motor 1 is both in operation and at rest.
[0056] The pins 41 do not necessarily need to be evenly distributed around the axis X.
[0057] In the embodiment described, the pin 41 does not necessarily need to protrude from the outer surface 31 . 2 of the yoke 31 .
[0058] Although in the present example the plate 42 is arranged to interact with a first end 41 . 1 of a pin 41 , it may also be arranged to interact with a second end 41 . 2 of said pin 41 .
[0059] The pin 41 may be replaced by any element forming a lug suitable for bayonet fastening. For example, the lug may be integral with the yoke 31 of the stator 30a, 30b.
[0060] Preferably, if Figure 4A As shown, pin 41 extends away from teeth 32 of yoke 31 to limit magnetic saturation of yoke 31 by the hole receiving pin 41. Another way to limit such magnetic saturation is to make pin 41 from a magnetic material, such as 15-5PH or 17-4PH stainless steel.
[0061] Although in this example the means 40a, 40b for securing the stators 30a, 30b comprise a single flange (formed by the plate 42) for securing a set of pins 41 in place, it may also comprise as many flanges as there are pins 41.
[0062] The recess 43 formed in the plate 42 may have a simple rectilinear shape with a single blind section for receiving the end 41 . 1 of the pin 41 and locking it against translation and rotation (the plate 42 is placed in the first part 10 . 1 of the housing 10 after the stator 30 a ).
[0063] Instead of the plate 42 , the fastening means 40 a , 40 b may comprise screws which pass through the housing and are screwed into threads arranged along the axis X in the first end 41 . 1 of the pin 41 , in order to lock the stator 30 a along and around the axis X.
Claims
1. An electric motor (1) comprising a housing (10) inside which are mounted at least one stator (30a, 30b) and a rotor (20) rotatable about an axis (X) relative to the stator, the rotor having magnetic poles, the stator comprising an ferromagnetic yoke (31) carrying a winding (33) arranged to generate an axial flux electric motor together with the magnetic poles of the rotor, characterized in that The stator is fixed in position relative to the housing by means of fastening means (40a, 40b), the fastening means comprising lugs (41.1, 41.2) projecting radially from the surface (42.1, 42.2) of the yoke and at least one fastening element (42) fastened to the housing and arranged to interact with the lugs to lock the stator along and around the axis (X).
2. The electric motor (1) according to claim 1, characterized in that The lug (41.1) protrudes from the inner surface (31.1) of the yoke (31).
3. An electric motor (1) according to any one of the preceding claims, characterised in that It comprises a pin (41) which is inserted into a hole made in the yoke (31) and has an end which projects radially from the surface of the yoke to form a lug (41.1).
4. An electric motor (1) according to any one of the preceding claims, characterised in that The lugs (41.1) are evenly distributed at angles around the axis (X).
5. An electric motor (1) according to any one of the preceding claims, characterised in that The yoke (31) of the stator (30a, 30b) is generally annular and includes a plurality of teeth (32), around which the winding (33) is wound, and the lug (41.1) extends away from the teeth (32).
6. An electric motor (1) according to any one of the preceding claims, characterised in that The fastening means (40a, 40b) comprises a single fastening element comprising a flange comprising a plate (42) provided with a bayonet fastening recess (43) adapted to receive the lug (41).
7. The electric motor (1) according to claim 6, characterized in that The plate (42) comprises an outer cylindrical bearing surface (42.2) arranged to interact with a corresponding bearing surface formed by an inner surface (31.1) of the stator (30a, 30b).
8. The electric motor (1) according to any one of claims 1 to 5, characterized in that The fastening means (40a, 40b) comprise a plurality of fastening elements, each fastening element comprising a screw which passes through the housing and is screwed along the axis (X) into a thread provided in one of the lugs (41.1).
9. An electric motor (1) according to any one of the preceding claims, characterised in that It comprises two identical stators (30a, 30b) extending symmetrically on both sides of the rotor (20).
10. An aircraft (A) comprising at least one landing gear (P) comprising a strut (J) mounted on the structure of the aircraft so as to be pivotable between a deployed position and a retracted position by means of an electric motor according to any one of the preceding claims.