Design and process for pressing long pin into stator laminate hole

Abstract

The invention relates to a design and process for pressing a long pin into a stator laminate hole. There is provided a method for securing a stator, comprising: aligning a pin with an opening in a stack of laminates; retaining the pin with a support, a surface of the support positioned at a distance from the laminate stack that is at least 40% of a length of the pin exposed outside the laminate stack; and press-fitting the pin into the opening. There is provided an electric machine comprising: a stator comprising a laminate stack having a first end and a second end and a lug attached to the laminate stack, the lug comprising an opening; and a pin disposed in press-fit relationship with the stator, the pin extending beyond the first end and the second end of the stator.

Description

Technical Field

[0001] This application claims priority to the prior filing date of U.S. Provisional Application Serial No. 63 / 589,893, filed on October 12, 2023, the entire disclosure of which is incorporated herein by reference. Background Art

[0002] Electric motors often combine components including conductive windings and thin metal laminations to form a stator. The stator must be aligned with the rotor to complete the motor. The thickness of the stator laminations is usually between 0.2mm and 0.3mm and is formed into a circle. The laminations are usually bonded or welded together and have an inner diameter, an outer diameter, and slots extending radially outward from the inner diameter. When the stator is formed from these components, the slots will accommodate the conductive windings. The rotor is usually placed inside the inner diameter of the stator and must be aligned with the stator within the motor.

[0003] Common techniques for aligning the stator with the rotor in an electric machine include fitting the outer diameter of a metal laminate into a precision crafted housing by a shrink fit or press fit operation. Another technique uses threaded fasteners to secure an extension of the laminate to the housing. While these techniques are effective, the shrink fit or press fit operation is also costly due to precision crafting and assembly, and the fastener-based approach is time consuming to minimize potential misalignment issues. Improved methods for producing aligned or alignable components would be beneficial to the art. Summary of the invention

[0004] A method for securing a stator is disclosed, comprising: aligning a pin with an opening in a lamination stack; holding the pin with a support, a surface of the support being positioned at a distance from the lamination stack, the distance being at least 40% of the length of the pin exposed outside the lamination stack; and press-fitting the pin into the opening.

[0005] An electric machine is disclosed, comprising: a stator, the stator comprising a laminate stack having a first end and a second end and an ear attached to the laminate stack, the ear comprising an opening; and a pin, the pin being arranged in a press-fit relationship with the stator, the pin extending beyond the first end and the second end of the stator. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The following description should not be considered limiting in any way. Referring to the drawings, similar elements are similarly numbered:

[0007] Figure 1 is a schematic diagram of the motor;

[0008] Figure 2It is a three-dimensional diagram of the stator;

[0009] Figure 3 yes Figure 2 An end view of a stator;

[0010] Figure 4 yes Figure 3 A magnified view of

[0011] Figure 5 is similar to Figure 4 A schematic diagram showing the dimensions;

[0012] Figure 6 is a view of a pin disclosed herein; and

[0013] Figure 7-Figure 11 is a series of views showing the insertion of a pin into a stator according to the present disclosure. DETAILED DESCRIPTION

[0014] With reference to the accompanying drawings, a detailed description of one or more embodiments of the disclosed apparatus and method is given herein by way of example and not limitation.

[0015] This article discloses a new method for securing the stator in the housing to ensure proper alignment with the rotor of the motor, which uses a close-fitting pin that is press-fit into the holes of the laminate to locate the stator assembly for initial alignment. If desired, threaded fasteners can also be used or some press fit in the housing, but due to the initial alignment, the required precision in the housing is reduced, and the use of threaded fasteners can reduce the amount of work and time because the alignment is already ensured.

[0016] refer to Figure 1 , schematically illustrating an electric machine 10. The electric machine 10 includes a housing 12, a stator 14 disposed in the housing 12 and aligned therein such that a rotor 16 rotatably supported by the housing will rotate within the stator 14.

[0017] refer to Figure 2 , the stator 14 is shown in a perspective view. The stator 14 includes slots 18 and includes ears 20 with openings 22 therein. It should be understood that the stator 14 includes a plurality of laminations that are not shown individually, but the slots 18 extend through all of the laminations, and the plurality of laminations have ears 20 that align with each other's lamination ears to form a row of ears, wherein the openings 22 form a tubular geometry. In some embodiments, the tubular geometry will also be substantially cylindrical in form, although cylindrical is not a limitation, but merely an example. In various embodiments, the length of the stator 14 measured axially can range from about 75 mm to about 250 mm.

[0018] Reference Figure 3-Figure 5, the focus is placed on the opening 22 and the ear 20 defining the opening 22. More specifically, with direct reference to Figure 5 , it will be appreciated that the radial dimension of the ear 20 at its radially outermost portion is less than 50% of the diameter of the opening 22. This is important to allow the laminate to deform slightly to accommodate the press fit interference (discussed below) of the pin. In an embodiment, a gap 24 is also provided at the radially outermost portion of the ear 20. The gap also helps to allow the opening to expand to accommodate the pin during assembly. In an embodiment, the width of the gap measured along the circumferential direction of the stator 14 can be about 0.4 mm to about 4 mm.

[0019] Reference Figure 6 , pin 26 is shown. In an embodiment, the diameter of pin 26 is about 10 mm, and the diameter of opening 22 is within about +0.02 mm to about -0.04 mm of the pin diameter. Different pin diameters are contemplated, with similar constraints associated with the diameter of the opening. The length of the pin extends about 25 mm to about 43 mm beyond the length of the stator 14. The extension distance helps position the stator 14 in the housing 12. The housing may include an opening to accommodate the pin, and the extension of the pin is positioned in the housing accordingly so that the stator is aligned in the housing. The cover for the housing may also have an opening that also accommodates the relative extension of the pin and ensures positioning and alignment with the housing and the cover.

[0020] The method requires pressing the pin 26 into the opening 22 of the stator 14. Because this is an interference fit and the pin 26 is relatively long and relatively thin, potential warping / bending of the pin 26 is an issue that needs to be addressed. The inventors have determined that the ratio of (pin diameter) / (laminate hole length) must be greater than 0.0464 to improve the reliability of pin insertion without bending / warping. Optionally, the hardness of the pin 26 is increased to greater than about 320HB (brinell hardness). It is also noted that the laminates used in the motor are stamped structures. As such, there is a burr on the downstream side of the laminate, and the downstream is defined by the direction in which the original stamp (stamp) moves relative to the blank used to produce the stator laminate. The inventors have determined that the insertion of the pin 26 should occur in the same downstream direction to avoid the burr causing additional resistance to insertion. Using these considerations and referring to Figure 7-10 , showing and defining the method of pin insertion.

[0021] Figure 7-Figure 11 The pin 26 is schematically shown in a position just arranged in the opening 22 of the ear 20 in the stator 14 until it is fully installed ( Fig.10 ) and becomes the final product ( Fig.11). It should also be noted that the stator 14, or at least the ears 20 of the stator 14, are clamped with clamps 28 and 30. These clamps apply pressure to the stator 14 and should be as close to the opening 22 as possible, for example within 7 mm of the opening 22, to avoid separation of the laminations of the stator 14. The support 32 supports the pin 26 through a clearance hole in the support 32, through which the pin 26 extends. The surface 34 of the support 32 is positioned at a distance from the stator end 36 closest thereto that is greater than 40% of the length of the entire pin 26. The thickness of the support measured in the same direction as the extension of the pin 26 is approximately the same as the expected extension of the pin from that end 36 or the opposite end (if applicable), or if a clamp is used, that length minus the thickness of the clamp (measured in the same direction). More specifically, since, as mentioned, an extension of the pin 26 relative to the stator 14 is expected, the support thickness should be approximately the same as the expected extension. In an embodiment, it is 25 mm at one end of the stator 14 and 40 mm at the other end of the stator 14. A load is then applied to the pin end 38 of the pin 26 and the support 32 so that both move together toward the stator 14 and force the pin 26 to move into the opening 22. When the support 32 contacts the clamp 28 (or the stator end 36 if no clamp is used), the support can be removed from the pin 26, leaving the stator ready to be installed in the housing.

[0022] Unless otherwise specified herein or clearly contradictory to the context, the use of the terms "a", "an" and "the" and similar indicators in the context of describing the present invention (particularly in the context of the following claims) should be interpreted as covering both the singular and the plural. In addition, it should be noted that the terms "first", "second", etc. herein do not indicate any order, quantity, or importance, but are used to distinguish one element from another. The terms "approximately", "substantially" and "typically" are intended to include the degree of error associated with the measurement of a specific amount of equipment available at the time of filing an application. For example, "approximately" and / or "substantially" and / or "typically" can include a range of ±8% of a given value.

[0023] Although the present invention has been described with reference to one or more exemplary embodiments, it will be appreciated by those skilled in the art that various changes may be made and elements thereof may be replaced with equivalents without departing from the scope of the present invention. In addition, many modifications may be made to adapt specific circumstances or materials to the teachings of the present invention without departing from the essential scope of the present invention. Therefore, it is intended that the present invention is not limited to the specific embodiments disclosed as the best mode for carrying out the present invention, but that the present invention will include all embodiments falling within the scope of the claims. In addition, in the drawings and descriptions, exemplary embodiments of the present invention have been disclosed, and although specific terms may have been employed, unless otherwise indicated, they are used only in a general and descriptive sense, and not for the purpose of limitation, and therefore the scope of the present invention is not limited thereto.

Claims

1. A method for fixing a stator, comprising: aligning the pins with the openings in the laminate stack; holding the pin with a support, a surface of the support being positioned at a distance from the laminate stack that is at least 40% of the length of the pin exposed outside the laminate stack; as well as The pin is press fit into the opening.

2. The method of claim 1, wherein the support member includes a second surface positioned at a distance from the laminate stack that is less than 40% of a length of the pin extending from the laminate stack. 3 . The method of claim 1 , wherein the retaining comprises moving the support with the pin during a press fit. The method according to claim 3 , wherein the movement is performed at the same speed as the pin. The method of claim 1 , wherein the support member includes an opening through which the pin passes.

6. The method of claim 1 wherein the press fitting is performed with a ratio of pin diameter to laminate opening length greater than 0.0464.

7. The method of claim 1, wherein the diameter of the pin and the diameter of the hole have a tolerance of +0.02 mm to -0.04 mm.

8. The method of claim 1, wherein the press fitting occurs in the same direction as the individual laminates are punched.

9. The method of claim 1, wherein the opening is located in an ear of the stator, the method further comprising clamping the ear prior to press fitting the pin.

10. The method of claim 9, wherein the clamping is performed at each end of the opening.

11. A motor, comprising: a stator comprising a laminate stack and an ear attached to the laminate stack, the laminate stack having a first end and a second end, the ear comprising an opening; and A pin, the pin being arranged in a press-fit relationship with the stator; The pin extends beyond the first end and the second end of the stator.

12. The electric machine of claim 11, wherein the ratio of the pin diameter to the laminate opening length is greater than 0.0464.

13. The electric machine of claim 11, wherein the press fit relationship includes a tolerance of +0.02 mm to -0.04 mm between the diameter of the pin and the diameter of the opening.

14. The electric machine of claim 11, wherein the pin has a hardness greater than about 320 Brinell hardness (HB).

15. The electric machine of claim 11, wherein a radial ear dimension radially outward of the opening is less than about 50% of a diameter of the opening.

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