Electric machine
The positive-locking connection between the stator and housing in electric machines addresses stress-related inefficiencies by using a deformable expansion element for low-stress fixation, improving efficiency and simplifying assembly and recycling.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- ROBERT BOSCH GMBH
- Filing Date
- 2025-12-03
- Publication Date
- 2026-07-02
AI Technical Summary
Existing electric machines face challenges in efficiently fixing the stator to the housing without causing stress, which leads to inefficiencies and complicates repairs and recycling.
A positive-locking connection between the stator and housing using a positive-locking element and a counter-positive-locking element, with a deformable expansion element to create a compression fit, allowing for low-stress fixation and easy assembly.
The solution minimizes iron losses, improves efficiency, simplifies assembly and disassembly, and reduces material waste, enhancing the overall performance and recyclability of the electric machine.
Smart Images
Figure EP2025085246_02072026_PF_FP_ABST
Abstract
Description
[0001] R.415162
[0002] - 1 -
[0003] Description
[0004] title
[0005] Electric machine
[0006] State of the art
[0007] The present invention relates to an electric machine. The electric machine features, in particular, an improved connection between the stator and the housing.
[0008] Electrical machines are known from the prior art that have a housing and a stator fixed in the housing. The housing is usually shrunk onto the stator by means of a shrink-fitting process. To prevent rotation of the stator relative to the housing, it is also known to provide axially extending recesses on the outer circumference of the stator. This is described, for example, in DE 102004007 322 A1.
[0009] Disclosure of the invention
[0010] The electric machine according to the invention allows for low-stress fixing of the stator in the housing by means of a positive fit. This low-stress fixing minimizes iron losses, which has a positive effect on the efficiency of the electric machine.
[0011] The electric machine has a housing and a stator arranged in the housing. The stator, in turn, has a stator core, which is in particular a laminated core. The stator core is ring-shaped around a stator axis. The stator axis is in particular a central axis of the electric machine and also, in particular, a rotational axis of a rotor of the electric machine. R.415162
[0012] - 2 -
[0013] The stator body is fixed to the housing for torque support via at least one positive-locking connection. The positive-locking connection comprises a positive-locking element and a counter-positive-locking element, wherein the positive-locking element and the counter-positive-locking element interlock. The positive-locking element is formed on the stator body, and the counter-positive-locking element is formed on the housing. Alternatively, the positive-locking element is provided on the housing and the counter-positive-locking element on the stator body.
[0014] The positive locking element projects radially with respect to the stator axis and extends axially. The counter-positive locking element is a groove-shaped recess extending axially. This recess is specifically designed in the radial direction. Thus, the projection of the positive locking element engages in the recess of the counter-positive locking element. In this way, a positive locking action is achieved at least in the circumferential direction and therefore in the direction of rotation of the electric machine, thus providing torque support of the stator to the housing. The counter-positive locking element, designed as a groove-shaped recess, can, in particular, have any inverse, partially inverse, or spaced contours of the positive locking element.
[0015] In particular, the mating form-locking element has a contour that corresponds to an offset on the outer contour of the form-locking element. This ensures that the form-locking element can engage with the mating form-locking element.
[0016] The positive locking element of the respective positive locking connection has a receptacle for an expansion element. The expansion element allows the positive locking element to be deformed, for which purpose the positive locking element can be deformed by inserting the expansion element into the receptacle. Deformation of the positive locking element creates a compression fit within the positive locking connection. The receptacle is typically a hollow profile. The insertion of the expansion element ensures, in particular, that a backlash-free connection is formed between the positive locking element and the mating positive locking element.
[0017] The expanding element advantageously has a profiled shape. In particular, the expanding element is designed as a bolt or as a rectangular or trapezoidal element. R.415162
[0018] - 3 -
[0019] A profile element is formed. By selecting the shape and / or size of the expanding element, the pressure in the positive locking connection can be adjusted.
[0020] The stator is fixed to the housing via at least one positive-lock connection. Multiple positive-lock connections are particularly advantageous, especially when they are evenly distributed around the stator axis. These positive-lock connections eliminate or significantly reduce the circumferential pressure exerted by the housing on the stator body. This results in the stator being arranged within the housing in a stress-free or at least low-stress manner, which improves the efficiency of the electric machine. Furthermore, the stator can be easily and quickly removed from the housing, simplifying both repairs and recycling of the electric machine.
[0021] The dependent claims describe preferred embodiments of the invention.
[0022] Preferably, the positive locking element of the respective positive locking connection is formed between two opposing flank walls. These flank walls are spaced apart from each other around the circumference of the stator body or housing. The flank walls interact positively with the groove flanks of the groove-shaped recess of the mating positive locking element. The stiffness of the positive locking element at the flank walls is particularly lower than the stiffness of the expanding element. In this way, the flank walls can be deformed by the expanding element. This makes the previously described pressure of the positive locking connection achievable.
[0023] It is particularly advantageous that the flank walls of the positive locking element of the respective positive locking connection are connected via an end wall. In this way, the receptacle is closed. A hollow profile is thus formed, which is particularly advantageous. The end wall is particularly straight or, alternatively, has a convex or concave curvature. The end wall connects the flank walls, making them stable and robust. The expanding element can be optimally received in the cavity formed by the side walls and the end wall. Excessive deformation of the flank walls is prevented.
[0024] - 4 -
[0025] prevented. If the flank wall is designed in such a way that it has a convex or concave curvature, a deformation characteristic of the form-locking element can be set by the spreading element.
[0026] Furthermore, it is particularly advantageous that at least one of the flank walls of the positive locking element of the respective positive locking connection is straight. Alternatively or additionally, the at least one flank wall has a convex or concave curvature. This allows, in particular, the creation of a preload against the expanding element. Again, the appropriate design of the concave and / or convex curvature allows for the adjustment of the deformation characteristics of the respective flank wall and thus of the positive locking element.
[0027] The flank walls of the positive locking element are spaced apart from each other at a distance smaller than one dimension of the expanding element. This allows the expanding element to be inserted between the flank walls only by deforming the flank walls. Inserting the expanding element into the receptacle inevitably leads to deformation of the flank walls. The deformation of the positive locking element can be adjusted by setting a desired overlap between the positive locking element and the expanding element. Furthermore, the degree of deformation can be defined by the difference between the distance of the flank walls and the dimension of the expanding element. This allows, in particular, the adjustment of the previously described contact pressure of the positive locking connection.
[0028] It is also particularly advantageous that the wall thickness of the positive-locking element is not constant along at least one of the flank walls in the radial direction. Preferably, said wall thickness is less at the radial end regions of the flank wall than at other regions. Thus, the wall thickness is particularly minimal at the radial end regions of the flank walls. The varying wall thicknesses allow for the targeted creation of areas with reduced strength, so that deformation preferably occurs in these areas. This means that different degrees of deformation can be achieved by means of R.415162 due to the varying wall thicknesses.
[0029] - 5 -
[0030] This can be achieved using expansion elements. This allows for an optimal positive locking connection.
[0031] It is also preferably provided that at least one of the flank walls has an insertion ramp at an axial end of the base body. Alternatively or additionally, the expanding element preferably has an insertion ramp at an axial end. Several insertion ramps at the same axial end or at opposite axial ends are also possible. Alternatively or additionally, it is preferably provided that at least one flank wall has an enlarged cross-section at an axial end of the base body for closing the groove-shaped recess of the mating element. Alternatively or additionally, the expanding element has such an enlarged cross-section at an axial end for closing the groove-shaped recess of the mating element. It is particularly advantageous that the flank walls have said insertion ramp at one axial end and said enlarged cross-section at another axial end.The same applies analogously to the spreading element, which, as an alternative to or in addition to the flank walls, may have the aforementioned insertion ramp and / or the aforementioned enlarged cross-section.
[0032] The positive locking element of the respective positive locking connection is advantageously formed by lamellar sections from several superimposed lamellae of the stator body. Thus, the stator body is particularly designed as a sheet metal lamella stack. The individual lamellae are particularly advantageously produced by stamping. The inventive configuration of the positive locking element enables, in particular, double-row stamping with a narrow coil width. This results in less waste during the stamping process, allowing for material-saving and therefore cost-effective stamping. Each of the individual lamellae has a suitable contour to form the positive locking element when stacked. In this way, the positive locking element can be manufactured simply and precisely.
[0033] The positive locking element preferably has at least one guide flank. The guide flank serves to guide the spreading element. The guide flank is particularly advantageous for centering the spreading element relative to the R.415162.
[0034] - 6 -
[0035] Positive locking element: Particularly in the case where the positive locking element is a hollow profile, the guide flank is advantageous to achieve a defined insertion of the expanding element. The guide flank can, for example, have a contour that is complementary to the outer contour of the expanding element. The guide flank is, in particular, a radially innermost flank of the positive locking element against which the expanding element rests.
[0036] The expanding element is advantageously supported against an inner wall of the mating element. This design is particularly advantageous when the mating element is designed as an open profile. In this case, the expanding element does not rest against the mating element on at least one side. Here, support against the mating element is advantageous. This ensures that the expanding element is fully supported and can optimally exert an expanding effect on the mating element.
[0037] The mating element preferably has a protrusion. The protrusion is designed to engage with a mating form of the mating element. Thus, the mating element is centered relative to the mating element by the protrusion and the mating form. Furthermore, at least a partially positive-locking connection is present. The mating element can therefore be reliably fitted into the mating element.
[0038] In a further preferred embodiment, the mating element has tapered or parallel groove flanks. If tapered groove flanks are present, it is particularly provided that the mating element forms a dovetail joint with the mating element. In this case, a positive fit between the mating element and the mating element is also present in the radial direction. This improves the retention of the mating element and the mating element relative to each other. Assembly is also advantageously simplified. If parallel groove flanks are present, a rectangular shape of the mating element is particularly provided. R.415162
[0039] - 7 -
[0040] The positive locking element and the counter-positive locking element preferably engage with clearance when the positive locking element is not deformed by the expansion element. This results in a robust manufacturing and assembly process, as the stator can be joined with clearance. This simplifies the assembly of the stator itself. The expansion element is pressed in relatively easily to secure it to the housing. This eliminates the need for a thermal process during manufacturing, as thermal processing of the housing and / or stator is unnecessary. Furthermore, it is not necessary to clean the previously manufactured stator, for example, by laser cleaning, which would be required after impregnation if the stator were thermally joined. Mounting the stator to the housing is thus significantly simplified. Nevertheless, secure, reliable, and, in particular, precise positioning of the stator within the housing is achieved.
[0041] Brief description of the drawings
[0042] Exemplary embodiments of the invention are described in detail below with reference to the accompanying drawings. The drawing shows:
[0043] Figure 1 shows a schematic view of an electric machine according to an embodiment of the invention.
[0044] Figure 2 shows a schematic top view of a stator and a rotor of the electric machine according to the embodiment of the invention.
[0045] Figure 3 shows a schematic spatial representation of the stator and rotor of the electric machine according to the embodiment of the invention.
[0046] Figure 4 shows a first schematic detail view of a connection between the stator and the housing of the electric machine according to the embodiment of the invention.
[0047] Figure 5 shows a second schematic detail view of the connection between the stator and the housing of the electric machine according to the embodiment of the invention, and R.415162
[0048] - 8 -
[0049] Figure 6 shows a schematic detail view of an alternative connection between the stator and the housing of the electric machine according to the embodiment of the invention.
[0050] Embodiments of the invention
[0051] Preferably, all identical components, elements and / or units in all figures are provided with the same reference numerals.
[0052] Figure 1 schematically shows an electric machine 1 according to an embodiment of the invention. The electric machine 1 has a stator 2 and a rotor 11. The stator has a stator winding 12 (see Figures 2 and 3) and is configured to drive the rotor 11. The rotor 11 can, for example, have permanent magnets, so that the electric machine 1 can be a permanent magnet synchronous machine. The type of electric machine 1 is fundamentally relevant for the invention according to the illustrated embodiment.
[0053] The stator 2 has a stator body 4, wherein the stator body 4 is in particular designed as a laminated core. The stator body 4 extends in a ring shape around a stator axis 100. The stator axis 100 is in particular also the axis of rotation of the rotor 11 and / or a central axis of the electric machine 1.
[0054] The stator 2 is arranged in a housing 3 of the electric machine 1. For this purpose, a positive-locking connection is provided between the stator 2 and the housing 3, which is described below.
[0055] The stator body 4 is fixed to the housing 3 for torque support via at least one positive-locking connection, wherein the positive-locking connection comprises a positive-locking element 5 and a counter-positive-locking element 6. The positive-locking element 5 and the counter-positive-locking element 6 engage with each other. It is provided that the positive-locking element 5 is located on the stator body 4 and the counter-positive-locking element 6 is located on the housing 3. In an alternative embodiment, the positive-locking element 5 can also be located on the housing 3 and the counter-positive-locking element R.415162
[0056] - 9 -
[0057] 6 is also provided on the stator body 4. In both cases, the positive locking element 5 projects radially 200 with respect to the stator axis 100 and extends axially 300 with respect to the stator axis 100. The counter-positive locking element 6 is a groove-shaped recess extending axially 300.
[0058] Figures 2 and 3 schematically show different views of the stator 1, including the rotor 11. The stator body 4 serves to hold the stator winding 12, and the rotor 11 of the electric machine 1 can be arranged within the stator body 4. The positive locking elements 5 of the stator body 4 project radially outwards. These positive locking elements 5 are distributed uniformly around the circumference 4a of the stator body 4. In the illustrated embodiment, three positive locking elements 5 are present, offset from each other by an angle of 120°. Such an arrangement is particularly advantageous when the positive locking elements 5, together with the stator body 4, are stacked from individual sheet metal laminations. In this case, the individual sheet metal laminations can be easily and cost-effectively stamped, as multi-row stamping processes can be used.This minimizes waste during the production of the lamellae.
[0059] Figures 4 and 5 show the positive locking connection between stator 2 and housing 3 formed by a positive locking element 5 and a counter-positive locking element 6. As previously described, the positive locking element 5 engages as a projection in the counter-positive locking element 6, which is designed as a groove. The engagement of the positive locking element 5 with the counter-positive locking element 6 is characterized by play. This simplifies the positioning of the positive locking element 5 within the counter-positive locking element 6. In particular, this simplifies the assembly of the stator 2 in the housing 3. After the stator 2 is positioned in the housing 3, an expanding element 8 can be inserted into the positive locking element 5. In the illustrated embodiment, the positive locking element 5 is designed as a hollow profile. The positive locking element 5 is provided with a receptacle 7 for receiving the expanding element 8.By inserting the expanding element 8 into the receptacle 7, the positive locking element 5 is deformable. In this way, a compression of the positive locking connection R.415162 is achieved.
[0060] - 10 -
[0061] trainable. Thus, after the insertion of the respective spreading elements 8, the stator 2 is connected to the housing 3 without play.
[0062] The stator 2 is firmly connected to the housing 3 for torque transmission by the described positive-lock connection. The assembly procedure for mounting the stator 2 to the housing 3 is simple.
[0063] In particular, no thermal treatment of the components is necessary, as would be required, for example, when shrinking the stator 2 into the housing 3. It is also not absolutely necessary to perform a complex cleaning of the stator 2, for example by laser cleaning, which is often required in conventional manufacturing processes after an impregnation step of the stator.
[0064] The expanding element 8 is, in particular, a profile element. In the exemplary embodiment, the expanding element 8 is a rod with a round cross-section. In principle, the expanding element 8 can also have other cross-sections, for example, rectangular or trapezoidal. It is provided that the positive locking element 5 is designed to be more easily deformable than the expanding element 8, so that primarily the positive locking element 5 is deformed when the expanding element 8 is inserted into the receptacle 7 of the positive locking element 5.
[0065] The recess 7 of the positive locking element 5 is formed between two opposing flank walls 5a, 5b. A first flank wall 5a and a second flank wall 5b extend radially away from the stator body 4 and are arranged on a circumference 4a of the stator body 4. A distance D between the opposing flank walls 5a, 5b is preferably selected such that it is less than a dimension L of the expanding element. In the illustrated embodiment, the dimension L is the diameter of the circular cross-section of the expanding element 8. In principle, the dimension L is the size of the expanding element 8 that lies between the flank walls 5a, 5b.
[0066] The first flank wall 5a and the second flank wall 5b of the positive locking element 5 interact positively with the respective groove flanks 6a of the groove-shaped recess of the counter-positive locking element 6. For this purpose, the respective flank walls 5a, 5b rest against the corresponding R.415162
[0067] - 11 -
[0068] The expanding element 8 is inserted into the receptacle 7 of the positive locking element 5, and the flank walls 5a, 5b are deformed and thereby pressed against the groove flanks 6a. In this way, a backlash-free mounting of the stator 2 in the housing 3 is achieved.
[0069] In the illustrated embodiment, the mating element 6 has parallel-oriented groove flanks 6a. These parallel-oriented groove flanks result in a groove-shaped recess in the mating element 6, which is particularly rectangular in shape. In an alternative embodiment, the mating element 6 can also have tapered groove flanks 6a. The tapered groove flanks 6a form, for example, a dovetail joint with the mating element 5.
[0070] In the illustrated embodiment, the flank walls 5a, 5b of the positive locking element 5 are connected via an end wall 5c. In this way, the receptacle 7 is closed and forms a hollow profile. The expanding element 8 is arranged within this hollow profile. The end wall can be straight, but in the illustrated embodiment it advantageously has a curvature.
[0071] In an alternative embodiment, if no end wall 5c is present, the side walls 5a, 5b form an open profile. In this case, it is advantageous if the expanding element 8 is supported against an inner wall 6b of the mating element 6. The inner wall 6b connects, in particular, the groove flanks 6a of the mating element 6. Thus, the mating element 5 remains reliably deformable by the expanding element 8, since movement of the expanding element 8, especially in the radial direction 200, is prevented by the support against the inner wall 6b.
[0072] The flank walls 5a, 5b of the positive locking element can be straight or have a convex or concave curvature. The shape of the flank walls allows, in particular, the desired deformation characteristic to be set when the expanding element 8 is inserted. In this way, a desired pressure between the positive locking element 5 and the counter-positive locking element 6 can also be achieved. R.415162
[0073] - 12 -
[0074] Furthermore, it is preferably provided that the wall thickness S of the positive locking element 5 is not constant along at least one of the flank walls 5a, 5b in the radial direction 200. Advantageously, the wall thickness S has its smallest value at the radial end regions of the flank walls 5a, 5b. In this way, a desired deformation characteristic can also be reliably set. This ensures reliable contact pressure between the positive locking element 5 and the counter-positive locking element 6, which leads to a secure hold of the stator 2 in the housing 3.
[0075] At least one of the flank walls 5a, 5b has an insertion ramp at an axial end of the base body 4. It is also preferred that the expanding element 8 has an insertion ramp at an axial end. This simplifies both the insertion of the stator body 4 into the housing 3 and the insertion of the expanding element 8 into the receptacle 7 of the positive locking element 5.
[0076] Furthermore, it is preferably provided that at least one flank wall 5a, 5b at another axial end of the base body 4 has an enlarged cross-section. In this way, the groove-shaped recess of the counter-form-locking element 6 at said axial end of the base body can be closed. In an alternative embodiment, the spreading element 8 can also have an enlarged cross-section at an axial end in order to close the groove-shaped recess of the counter-form-locking element 6.
[0077] To reliably guide the expanding element 8 in the guide 7, the positive locking element 5 has at least one guide flank 5d. The guide flank 5d serves to guide, and in particular center, the expanding element 8 in the receptacle 7. Thus, the expanding element 8 is reliably held in the desired position in the receptacle 7. This allows the expanding element 8 to optimally deform the positive locking element 5.
[0078] Figure 6 shows an alternative embodiment of the counter-form-locking element 6. Analogous to Figures 4 and 5, the form-locking element has a concave bulge that serves as a counter-form 10 to interact with a bulge 9 of the inner wall 6b of the counter-form-locking element 6, which, unlike in Figures 4 and 5, is present. In this way, a
[0079] - 13 -
[0080] Centering of the positive locking element 5 and the counter-positive locking element 6 enables this, which is achieved by positive locking of the bulge 9 and the counter-form 10.
[0081] All previously described variants of the positive-locking connection between housing 3 and stator 2 are based on the creation of a positive-locking connection, particularly one that is initially backlash-free, between the positive-locking elements 5 and the mating positive-locking elements 6, followed by crimping. To crimp the respective positive-locking connections, an expanding element 8 is inserted into a receptacle 7 of the positive-locking elements 5, which deforms the positive-locking elements 5. Thus, the stator 2 can be mounted easily and with minimal effort, ensuring reliable retention of the stator 2 in the housing 3.
Claims
R.415162 - 14 - Claims 1. Electric machine (1) comprising a housing (3) and a stator (2) arranged in the housing (3), • wherein the stator (2) comprises a stator body (4), in particular a laminated core, which is formed in a ring shape around a stator axis (100), • wherein the stator body (4) is fixed to the housing (3) for torque support via at least one positive locking connection, wherein the positive locking connection comprises a positive locking element (5) and a counter-positive locking element (6), wherein the positive locking element (5) and the counter-positive locking element (6) interlock, • wherein the positive locking element (5) is provided on the stator body (4) and the counter-positive locking element (6) is provided on the housing (3) or wherein the positive locking element (5) is provided on the housing (3) and the counter-positive locking element (6) is provided on the stator body (4), • wherein the positive locking element (5) projects radially (200) with respect to the stator axis (100) and extends axially (300), and • wherein the counter-form-locking element (6) is a groove-shaped recess extending in the axial direction (300), characterized by the fact that the positive locking element (5) of the respective positive locking connection has a receptacle (7) for receiving an expanding element (8), is deformable by inserting the expanding element (8) into the receptacle (7) to form a pressure in the positive locking connection and is in particular a hollow profile.
2. Electric machine (1) according to claim 1, characterized in that the receptacle (7) of the positive locking element (5) of the respective positive locking connection is formed between two opposing flank walls (5a, 5b) which are formed at a distance (D) from each other on the circumference (4a) of the stator body (4) or the housing (3) and with R.415162 - 15 - The groove flanks (6a) of the groove-shaped recess of the counter-form-locking element (6) interact in a form-locking manner.
3. Electric machine (1) according to claim 2, characterized in that the flank walls (5a, 5b) of the positive locking element (5) of the respective positive locking connection are connected via an end wall (5c) to close the receptacle (7), in particular to form a hollow profile, wherein the end wall (5c) is in particular straight or in particular has a convex or concave curvature.
4. Electric machine (1) according to claim 2 or 3, characterized in that at least one of the flank walls (5a, 5b) of the positive locking element (5) of the respective positive locking connection is straight or has a convex or concave curvature.
5. Electric machine (1) according to one of claims 2 to 4, characterized in that the flank walls (5a, 5b) of the positive locking element (5) have a distance (D) to each other which is less than a dimension (L) of the spreading element (8).
6. Electric machine (1) according to one of claims 2 to 5, characterized in that a wall thickness (S) of the positive locking element (5) along at least one of the flank walls (5a, 5b) in radial direction (200) is not constant and in particular preferably has a minimum value at radial end regions of the flank wall (5a, 5b).
7. Electric machine (1) according to one of claims 2 to 6, characterized in that, • that at least one of the flank walls (5a, 5b) at an axial end of the base body (4) and / or the spreading element (8) has an insertion ramp, and / or • that at least one flank wall (5a, 5b) at another axial end of the base body (4) and / or the spreading element (8) has an enlarged cross-section for closing the groove-shaped recess of the counter-form-locking element (6). R.415162 - 16 - 8. Electric machine (1) according to one of the preceding claims, characterized in that the positive locking element (5) of the respective positive locking connection is formed by lamellar sections of several superimposed lamellae of the stator body.
9. Electric machine (1) according to one of the preceding claims, characterized in that the positive locking element (5) has at least one guide flank (5d) for guiding, in particular centering, the spreading element (8).
10. Electric machine (1) according to one of the preceding claims, characterized in that the spreading element (8) is supported on an inner wall (6b) of the counter-form-locking element (6).
11. Electric machine (1) according to one of the preceding claims, characterized in that an inner wall (6b) of the counter-form-locking element (6) has a protrusion (9) which engages in a counter-form (10) of the form-locking element (5).
12. Electric machine (1) according to one of the preceding claims, characterized in that the counter-form-locking element (6) • has tapered groove flanks (6a) to form a dovetail joint with the positive locking element (5), or • has parallel oriented groove flanks (6a).
13. Electric machine (1) according to one of the preceding claims, characterized in that the positive locking element (5) and the counter-positive locking element engage with clearance when the positive locking element (5) is not deformed by the spreading element (8).