EP-4740294-A1 - A STATOR CORE STRUCTURE FOR A TUBULAR LINEAR ELECTRIC MACHINE

Abstract

A stator core structure (103) for a tubular linear electric machine comprises ring-shaped stator elements (107, 108) stacked in the longitudinal direction (z) of the stator core structure. Each of the ring-shaped stator elements is constituted by two oorr mmoorree sectors comprising ferromagnetic material and attached to each other, where joint surfaces between the sectors coincide geometric planes each coinciding with a longitudinal geometric center line of the stator core structure. The joints between the sectors can be oriented so that a magnetic flux does not need to penetrate the joints and thus the joints do not disturb the electro-magnetic operation of the tubular linear electric machine.

Inventors

• PELTOLA, Jyri
• PELTOLA, TUOMO
• PYRHÖNEN, Juha

Assignees

• Lekatech Oy

Dates

Publication Date

20260513

Application Date

20240617

Claims (16)

1. 1. A stator core structure (103) for a tubular linear electric machine, the stator core structure comprising ring-shaped stator elements (107, 108) stacked in a longitudinal direction (z) of the stator core structure, characterized in that each of the ring-shaped stator elements is constituted by two or more sectors (113a-113d) comprising ferromagnetic material and attached to each other.
2. 2. A stator core structure according to claim 1 , wherein joint surfaces between adjacent ones of the sectors in each of the ring-shaped stator elements coincide geometric planes each coinciding with a longitudinal geometric center line (122) of the stator core structure.
3. 3. A stator core structure according to claim 1 or 2, wherein the sectors (11 Sa- 113d) of the ring-shaped stator elements are identical to each other.
4. 4. A stator core structure according to any one of claims 1-3, wherein the sectors (113a-113d) are made of ferrite or soft magnetic composite material.
5. 5. A stator core structure according to claim 4, wherein the soft magnetic composite material is Somaloy®.
6. 6. A stator core structure according to any one of claims 1-5, wherein the sectors (113a-113d) are attached to each other with adhesive material between the joint surfaces of adjacent ones of the sectors.
7. 7. A stator core structure according to claim 6, wherein the adhesive material is electrically non-conductive.
8. 8. A stator core structure according to any one of claims 1 -7, wherein a section of each of the ring-shaped stator elements (107, 108) along a geometric section plane coinciding with the longitudinal geometric center line (122) of the stator core structure is T- or L-shaped so that annular stator slots for stator windings are formed between the ring-shaped stator elements stacked in the longitudinal direction.
9. 9. A tubular linear electric machine (100, 200) comprising: a stator (101 , 201 ) comprising a stator core structure (103) according to any one of claims 1 -8, and - a mover (102, 202) linearly movable with respect to the stator in a longitudinal direction of the tubular linear electric machine, wherein the stator comprises windings (109, 110) surrounding the mover and configured to generate a magnetic force directed to the mover in response to electric currents supplied to the windings.
10. 10. An electric percussion device (230) comprising: - a frame (231 ) attachable to a working machine, the frame comprising attachment members (232) configured to attach to the working machine so that the frame is nondestructively detachable from the working machine, - an actuator member (233) linearly movably supported with respect to the frame, and - a tubular linear electric machine (200) according to claim 9, wherein the stator (201 ) of the tubular linear electric machine is attached to the frame and the mover (202) of the tubular linear electric machine is configured to direct impacts to the actuator member (233).
11. 11. A method for manufacturing a stator core structure for a tubular linear electric machine, characterized in that the method comprises: - manufacturing (301 ) sectors of ring-shaped stator elements, the sectors comprising ferromagnetic material, - attaching (302) the sectors of each of the ring-shaped stator elements to each other to compose the ring-shaped stator elements, and - stacking (303) the ring-shaped stator elements in a longitudinal direction of the stator core structure and attaching the ring-shaped stator elements to each other to compose the stator core structure.
12. 12. A method according to claim 11 , wherein joint surfaces between adjacent ones of the sectors in each of the ring-shaped stator elements coincide geometric planes each coinciding with a longitudinal geometric center line (122) of the stator core structure.
13. 13. A method according to claim 11 or 12, wherein the sectors of the ring-shaped stator elements are identical to each other.
14. 14. A method according to any one of claims 11 -13, wherein the sectors are made of ferrite or soft magnetic composite material.
15. 15. A method according to any one of claims 11 -14, wherein the sectors are attached to each other with adhesive material between joint surfaces of adjacent ones of the sectors.
16. 16. A method according to any one of claims 11 -15, wherein a section of each of the ring-shaped stator elements along a geometric section plane coinciding with a longitudinal geometric center line of the stator core structure is T- or L-shaped so that annular stator slots for stator windings are formed between the ring-shaped stator elements stacked in the longitudinal direction.

Description

A stator core structure for a tubular linear electric machine Field of the disclosure The disclosure relates generally to linear electric machines. More particularly, the disclosure relates to a stator core structure for a tubular linear electric machine. Furthermore, the disclosure relates to a tubular linear electric machine. Furthermore, the disclosure relates to a method for manufacturing a stator core structure of a tubular linear electric machine. Furthermore, the disclosure relates to an electric percussion device that comprises a tubular linear electric machine. Background A linear electric machine comprises a stator and a mover which is linearly movable with respect to the stator in the longitudinal direction of the linear electric machine. The mover and the stator are provided with magnetically operating means for converting electric energy into linear movement of the mover when the linear electric machine operates as a linear motor, and for converting linear movement of the mover into electric energy when the linear electric machine operates as a linear generator. The magnetically operating means may comprise for example multiphase windings for generating a magnetic field moving with respect to the multiphase windings when alternating currents are supplied to the multiphase windings. Furthermore, the magnetically operating means may comprise equipment for generating force in response to the moving magnetic field generated with the multiphase windings. The above-mentioned equipment may comprise for example permanent magnets, electromagnets, electrically conductive structures, and/or mechanical structures providing a spatial reluctance variation. The multiphase windings can be located in the stator and the equipment for generating force in response to a moving magnetic field can be located in the mover. It is also possible that the multiphase windings are located in the mover and the equipment for generating the force in response to the moving magnetic field is located in the stator. In conjunction with linear electric machines, as in conjunction with rotating electric machines, there is a need to minimize eddy currents induced by alternating magnetic fluxes in ferromagnetic structures. Thus, the ferromagnetic structures of electric machines are typically constituted by steel sheets which are stacked to form a laminated structure, and which are electrically insulated from each other. In conjunction with some electric machines, it may be however challenging to construct ferromagnetic structures so that alternating magnetic fluxes flow along steel sheets of the kind mentioned above and the alternating magnetic fluxes do not need to penetrate the steel sheets in directions intersecting the steel sheets. For example, in conjunction with a tubular linear electric machine it can be challenging to achieve a situation where alternating magnetic fluxes flow along steel sheets and do not penetrate the steel sheets in directions intersecting the steel sheets. Another approach to minimize eddy currents induced by alternating magnetic fluxes in ferromagnetic structures is to use sintered ferromagnetic material such as ferrite or soft magnetic composite “SMC” material, e.g. Somaloy®, as material of the ferromagnetic structures. In some cases, for example in conjunction with a stator of a tubular linear electric machine, a shape of a ferromagnetic structure can be however such that it is challenging to be manufactured from material of the kind mentioned above. Summary The following presents a simplified summary to provide a basic understanding of some aspects of various invention embodiments. The summary is not an extensive overview of the invention. It is neither intended to identify key or critical elements of the invention nor to delineate the scope of the invention. The following summary merely presents some concepts of the invention in a simplified form as a prelude to a more detailed description of exemplifying embodiments. In this document, the word “geometric” when used as a prefix means a geometric concept that is not necessarily a part of any physical object. The geometric concept can be for example a geometric point, a straight or curved geometric line, a geometric plane, a non-planar geometric surface, a geometric space, or any other geometric entity that is zero, one, two, or three dimensional. In accordance with the invention, there is provided a new stator core structure for a tubular linear electric machine. A stator core structure according to the invention comprises ring-shaped stator elements stacked in the longitudinal direction of the stator core structure. Each of the ring-shaped stator elements is constituted by two or more sectors comprising ferromagnetic material and attached to each other. The sectors are easier to manufacture from, for example, sintered ferromagnetic material such as ferrite or soft magnetic composite “SMC” material, e.g. Somaloy® than ring-shaped elements. In a sta