Electric machine

Abstract

Electric machine (10), comprising: a stator body (20, 120) with a stator ring (22, 122) of a generally ring-shaped form and a plurality of stator teeth (24, 124) projecting radially inwards from the stator ring (22, 122); a machine housing (12); a first screw hole (32, 132) defined either in the stator ring (22, 122) or in the machine housing (12), and a first receptacle (42) defined in the other from the stator ring (22, 122) and the machine housing (12) and coaxial with the first screw hole (32, 132); a second screw hole (32, 132) defined either in the stator ring (22, 122) or in the machine housing (12), and a second receptacle (42) defined in the other from the stator ring (22, 122) and the machine housing (12) and coaxial with the second screw hole (32, 132); a first countersunk bore (45) which is coaxial with the first receptacle (42) and has the same diameter as the first screw hole (32, 132); and a first hollow pin (51) adapted to the first countersunk hole (45) and the first screw hole (32, 132), wherein the first hollow pin (51) defines a first pin hole (53) coaxial with the first countersunk hole (45) and the first screw hole (32, 132).

Description

TECHNICAL FIELD

[0001] This disclosure generally relates to electrical machines such as motors / generators. BACKGROUND

[0002] An electric motor uses potential electrical energy to generate mechanical energy through the interaction of magnetic fields and current-carrying conductors. The reverse process, the use of mechanical energy to generate electrical energy, is accomplished by a generator or dynamo. Drive motors used in hybrid, electric, and hybrid-electric vehicles often perform both tasks. Other electrical machines, such as motor / generators, combine various features of both motors and generators.

[0003] Electric machines may include an element that is rotatable about a central axis. The rotating element, which may be called a rotor, may be coaxial with a static element, which may be called a stator. The electric machine uses relative rotation between the rotor and stator to generate mechanical or electrical energy.

[0004] DE 18 99 876 U discloses an electrical machine with a stator body and a machine housing, wherein screw holes are defined in the stator body and coaxial receptacles are defined in the machine housing for screwing the stator body to the machine housing.

[0005] US 2,560,413 A discloses a hollow pin having a pin hole designed to receive a screw. The hollow pin is arranged in an opening formed in two parts to be joined.

[0006] The object of the invention is to simplify the manufacture and assembly of an electrical machine and thus to save costs.

[0007] This object is achieved by the electrical machines according to claims 1 and 8. SUMMARY

[0008] An electric machine is provided having a stator body and a machine housing. The stator body includes a stator ring of generally annular shape and a plurality of stator teeth projecting radially inwardly from the stator ring. A first bolt hole is defined in one of the stator ring and the machine housing, and a first receptacle is defined in the other of the stator ring and the machine housing and coaxial with the first bolt hole. A second bolt hole is defined in one of the stator ring and the machine housing, and a second receptacle is defined in the other of the stator ring and the machine housing and coaxial with the second bolt hole.

[0009] A first counterbore is coaxial with the first receptacle and has the same diameter as the first screw hole. A first hollow pin is aligned with the first counterbore and the first screw hole. The first hollow pin defines a first pin hole that is coaxial with the first counterbore and the first screw hole. The electric machine may be characterized by the absence of a stator housing between the stator body and the machine housing.

[0010] The foregoing features and advantages and other features and advantages of the present invention will be readily apparent from the following detailed description of some of the best modes and other embodiments for carrying out the invention as defined in the appended claims when read in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1A is a schematic cross-sectional view of a portion of an electric machine having a stator with a solid stator body; Fig. Figure 1B is a schematic cross-sectional view of a portion of the Fig. 1A, which shows a receptacle without a counterbore; and Fig. 2 is a schematic isometric view of a stator for an electrical machine, the stator having bolt lugs and laminations. DETAILED DESCRIPTION

[0011] With reference to the drawings, in which like reference numerals correspond to the same or similar components in the different figures, Fig. 1A and Fig. 1B shows a schematic cross-sectional view of an electric machine 10 of the type that may be used in a hybrid, electric, or hybrid electric vehicle. Fig. 1A shows a complete cross-section of the electric machine 10, while Fig. 1B shows a section of a cross-section corresponding to the Fig. 1A is rotated approximately ninety degrees. In addition to several other components (not shown), the electric machine 10 includes a machine housing 12 having a rotor 14 and a stator assembly 16 generally disposed within or located within the machine housing 12. The machine housing 12 may be a housing for only the electric machine 10, or it may be a transmission housing (box) for a transmission (not shown) into which the electric machine is incorporated.

[0012] Although the present invention will be described in detail with reference to automotive applications, those skilled in the art will recognize the broader applicability of the invention. Those skilled in the art will recognize that terms such as "over," "under," "upward," "downward," etc., are used to describe the figures and do not represent limitations on the scope of the invention, which is defined by the appended claims.

[0013] The stator assembly 16 includes windings 18 and a stator body 20. The Fig. 1A and Fig. 1B is a solid body. The stator body 20 includes a generally annular stator ring 22 and a plurality of stator teeth 24 projecting radially inwardly from the stator ring 22 (many of the stator teeth 24 are in Fig. 1A and Fig. 1B, but they are similar to those shown in Fig. 2). Applying a voltage to the windings 18 causes a torque difference between the stator assembly 16 and the rotor 14.

[0014] The windings 18 shown in the figures consist of single-core wire coils, but they may be multi-core wires or conductors. Winding patterns of the stator assembly 16 may be concentrated windings, distributed slot windings, fractional slot windings, or other winding patterns known to those skilled in the art. In concentrated winding patterns, the coil is wound in a concentrated manner on each stator tooth 24. In distributed winding patterns, the coil is wound over a plurality of stator teeth 24 through a plurality of stator slots between the stator teeth 24. Furthermore, any of the winding patterns may include windings 18 with a rectangular cross-section (as in Fig. 1A) as conductors to increase the slot filling in the stator slots, or they can use windings 18 with a circular cross-section.

[0015] The stator body 20 is attached or adapted to the machine housing 12 with a plurality of screws 30. At least two screw holes 32 are defined through the stator body 20. The stator body 20 further includes at least four screw holes 32 defined through the stator body 20. In the Fig. 1A and Fig. 1B there are four screw holes 32, the first and third screw holes 32 in Fig. 1A and the second and fourth screw holes 32 are rotated by approximately ninety degrees to the first and third screws 32, as shown in Fig. 1B. The screw holes 32 may be labeled or designated as first, second, third, or fourth in any order or combination. The first through fourth screw holes 32 may be defined directly through the stator ring 22 or by corresponding screw tabs or eyes extending radially outward from the stator ring 22 (in Fig. 1A and Fig. 1B, but may be similar to those shown in Fig. 2 are shown).

[0016] The machine housing 12 includes first, second, third, and fourth receptacles 42 that are coaxial with respective first through fourth screw holes 32. As used herein, the term coaxial generally refers to holes or objects that ideally have the same or overlapping axes. However, due to variations in manufacturing and assembly, having the exact same axis may not always occur in actual components or assemblies. Coaxial can refer to objects or holes that have a slight variation, offset, or angle between the respective axes.

[0017] If the stator body 20 contains more or fewer than four screw holes 32, the machine housing 12 may also contain more or fewer than four receptacles 42. The first and third receptacles 42 of the machine housing 12 are in Fig. 1A and the second and fourth frames 42 are rotated by approximately ninety degrees relative to the first and third frames 42, as shown in Fig. 1B. The receptacles 42 may be labeled or designated as first, second, third, or fourth in any order or combination.

[0018] The machine housing 12 further includes a first counterbore 45 coaxial with the first receptacle 42 and a second counterbore 46 coaxial with the third receptacle 42. The second and fourth receptacles 42 do not include counterbore sections, as in Fig. 1B. A first hollow pin 51 is fitted to the first counterbore 45 and the first screw hole 32 and defines a first pin hole 53 coaxial with the first counterbore 45 and the first screw hole 32. A second hollow pin 52 is fitted to the second counterbore 46 and the third screw hole 32 and defines a second pin hole 54 coaxial with the second counterbore 46 and the third screw hole 32.

[0019] The screws 30 extend through the first through fourth screw holes 32 and engage the first through fourth receptacles 42. The screws 30 and portions of the first through fourth receptacles 42 may have cooperating threaded portions. Each of the first through fourth screw holes is substantially identical. However, the screws 30 that extend through the first screw hole 32 and the third screw hole 32 also extend through the first pin hole 53 and the second pin hole 54.

[0020] The electric machine 10 does not include a stator housing or stator container between the stator body 20 and the machine housing 12. Therefore, loads are transferred from the stator body 20 to the machine housing 12 via one of the screws 30, the first and second hollow pins 51, 52, or the interface between the stator body 20 and the machine housing 12 (by a clamping force generated by the screws 30).

[0021] During assembly of the electric machine 10, the first and second hollow pins 51, 52 are placed in the first and second counterbores 45, 46. The stator assembly 16 can be completed as a module prior to assembly of the electric machine 10. The first screw hole 32 and the third screw hole 32 can then be aligned with the first and second hollow pins 51, 52, respectively.

[0022] Aligning the first screw hole 32 with the first hollow pin 51 and the third screw hole 32 with the second hollow pin 52 orients the stator body 20 relative to the machine housing 12. Therefore, the stator body 20 is positioned substantially coaxially with the machine housing 12. The screws 30 can then be inserted and used to attach the stator assembly 16 to the machine housing 12.

[0023] In Fig. 1, the screws 30 are shown securing the stator assembly 16 to the machine housing 12 such that the screws 30 extend through the stator body 20 (when viewed in Fig. 1 from right to left). However, the electric machine 10 can also be designed such that the screws 30 fasten the machine housing 12 to the stator assembly 16 by being screwed into receptacles 42 defined in the stator body 20 (when viewed from Fig. 1 inserted from left to right). In such a configuration (not shown), the counterbores 45, 46 would be formed in the stator body 20, and the bolt holes 32 would be defined by and extend through the machine housing 12. The first and second hollow pins 51, 52 would be substantially identical and would serve substantially identical functions in each configuration.

[0024] In Fig. 2 is a schematic isometric view of another stator assembly 116 associated with the electric machine 10 and the machine housing 12 shown in Fig. 1A and Fig. 1B, or with a similar electrical machine and a similar housing. As shown in Fig. 2, the stator assembly 116 includes a stator body 120 with a stator ring 122 and stator teeth 124. Windings 118 are wound through the stator teeth 124.

[0025] The stator body 120 also includes first through fourth screw holes 132 defined therethrough. Like the stator assembly 16 shown in Fig. 1A and Fig. 1B, the stator assembly 116 is designed for attachment to the machine housing 12 without an intermediate stator housing or stator container, and loads are transferred directly between the stator body 120 and the machine housing 12. Unlike the Fig. 1A and Fig. However, unlike the stator body 20 shown in Figure 1B, the stator body 120 includes first through fourth bolt tabs 136 extending radially outward from the stator ring 122. The bolt tabs 136 provide bosses through which the bolt holes 132 are defined and do not require further expansion of the stator ring 122 to accommodate the bolt holes 132.

[0026] Unlike the one in Fig. 1A and Fig.1B, the stator body 120 is further formed by a plurality of laminations 156. The laminations 156 are assembled and cooperate to define the plurality of stator teeth 124, the stator ring 122, the first through fourth bolt holes 132, and the first through fourth bolt tabs 136. Because the first through fourth bolt holes 132 are substantially identical, the laminations 156 may each be substantially identical and may also be radially symmetrical, such that the illustrated laminations 156 may be rotated ninety degrees relative to each other without affecting the assembled stator body 120.

[0027] The detailed description and the drawings or figures support and describe the invention, but the scope of the invention is defined only by the claims. While some of the best modes and other embodiments for carrying out the claimed invention have been described in detail, various alternative designs and embodiments exist for practicing the invention defined by the appended claims.

Claims

[1] Electrical machine (10), comprising: a stator body (20, 120) having a stator ring (22, 122) of generally annular shape and a plurality of stator teeth (24, 124) projecting radially inwardly from the stator ring (22, 122); a machine housing (12); a first screw hole (32, 132) defined in one of the stator ring (22, 122) and the machine housing (12), and a first receptacle (42) defined in the other of the stator ring (22, 122) and the machine housing (12) and coaxial with the first screw hole (32, 132); a second screw hole (32, 132) defined in one of the stator ring (22, 122) and the machine housing (12), and a second receptacle (42) defined in the other of the stator ring (22, 122) and the machine housing (12) and coaxial with the second screw hole (32, 132); a first counterbore (45) coaxial with the first receptacle (42) and having the same diameter as the first screw hole (32, 132); and a first hollow pin (51) adapted to the first counterbore (45) and the first screw hole (32, 132), the first hollow pin (51) defining a first pin hole (53) coaxial with the first counterbore (45) and the first screw hole (32, 132). [2] The electric machine (10) of claim 1, wherein the first screw hole (32, 132) and the first hollow pin (51) are configured to orient the stator body (20, 120) relative to the machine housing (12) such that the stator body (20, 120) is coaxial with the machine housing (12). [3] Electric machine (10) according to claim 2, wherein the electric machine (10) is characterized by the absence of a stator housing between the stator body (20, 120) and the machine housing (12). [4] The electric machine (10) of claim 3, wherein the first screw hole (32, 132) and the second screw hole (32, 132) are defined in the stator body (20, 120), the first receptacle (42), the second receptacle (42) and the first counterbore (51) are defined in the machine housing (12), and further comprising: wherein the stator body (20, 120) further includes: a third screw hole (32, 132) defined in the stator body (20, 120), and a fourth screw hole (32, 132) defined in the stator body (20, 120); wherein the machine housing (12) further comprises: a third receptacle (42) defined in the machine housing (12) and coaxial with the third screw hole (32, 132), a fourth receptacle (42) defined in the machine housing (12) and coaxial with the fourth screw hole (32, 132); and a second counterbore (46) coaxial with the third receptacle (42) and having the same diameter as the third screw hole (32, 132); and a second hollow pin (52) adapted to the second counterbore (46) and the third screw hole (32, 132), the second hollow pin (52) defining a second pin hole (54) coaxial with the second counterbore (46) and the third screw hole (32, 132). [5] The electric machine (10) of claim 4, wherein the third screw hole (32, 132) and the second hollow pin (52) are configured to orient the stator body (20, 120) relative to the machine housing (12) such that the stator body (20, 120) is coaxial with the machine housing (12). [6] The electric machine (10) of claim 5, wherein the stator body (120) further comprises: a first screw tab (136) defining the first screw hole (132); a second screw tab (136) defining the second screw hole (132); a third screw tab (136) defining the third screw hole (132); a fourth screw tab (136) defining the fourth screw hole (132); and wherein the first to fourth screw tabs (136) extend radially outwardly from the stator ring (122). [7] The electric machine (10) of claim 6, wherein the stator body (120) is formed by a plurality of lamination stacks (156) such that the plurality of lamination stacks (156) cooperate to define the plurality of stator teeth (124), the stator ring (122), and the first to fourth screw tabs (136). [8] Electrical machine (10), comprising: a stator body (120) comprising: a stator ring (122) having a generally annular shape, a plurality of stator teeth (124) projecting radially inwardly from the stator ring (122), a first screw tab (136) extending radially outward from the stator ring (122) and defining a first screw hole (132), and a second screw tab (136) extending radially outward from the stator ring (122) and defining a second screw hole (132); a machine housing (12) containing: a first receptacle (42) defined in the machine housing (12) and coaxial with the first screw hole (132), a second receptacle (42) defined in the machine housing (12) and coaxial with the second screw hole (132), and a first counterbore (45) coaxial with the first receptacle (42) and having the same diameter as the first screw hole (132); and a first hollow pin (51) adapted to the first counterbore (45) and the first screw hole (132), the first hollow pin (51) defining a first pin hole (53) coaxial with the first counterbore (45) and the first screw hole (132). [9] Electric machine (10) according to claim 8, wherein the electric machine (10) is characterized by the absence of a stator housing between the stator body (120) and the machine housing (12). [10] Electric machine (10) according to claim 9, further comprising: wherein the stator body (120) further includes: a third screw tab (136) extending radially outward from the stator ring (122) and defining a third screw hole (132), and a fourth screw tab (136) extending radially outward from the stator ring (122) and defining a fourth screw hole (136); wherein the machine housing (12) further contains: a third receptacle (42) defined in the machine housing (12) and coaxial with the third screw hole (132), a fourth receptacle (42) defined in the machine housing (12) and coaxial with the fourth screw hole (132), and a second counterbore (46) coaxial with the third receptacle (42) and having the same diameter as the third screw hole (132); and a second hollow pin (52) adapted to the second counterbore (46) and the third screw hole (132), the second hollow pin (52) defining a second pin hole (54) coaxial with the second counterbore (46) and the third screw hole (136).

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