METHOD FOR FITTING A STATOR INTO A HOUSING, INCLUDING ROUNDED ANGLE MACHINING AND CUTTING OF STATOR SHEETS, STATOR, HOUSING, VEHICLE AND PROGRAM BASED ON SUCH A METHOD

Abstract

The invention relates to a shrink-fit method for an electrical machine stator (S) in a housing (C), comprising: - a machining step of a receiving portion (R) of the housing (C) to create a rounded corner junction surface (J); - a trimming step in which the size of the peripheral laminations (TP) is reduced relative to that of the central laminations (TC) forming the stator (S); and - a shrink-fitting step of the stator (S) in the housing (S) such that the laminations (TC, TP) bear against the shoulder portion (E), and the peripheral laminations (TP) are not in contact with the bottom wall (F) of the housing (C). The invention also relates to a stator, a housing, a vehicle, and a program based on such a method. Figure 4

Description

Title of the invention: METHOD FOR SHRINK-FITTING A STATOR INTO A CASING, COMPRISING ROUNDED ANGLE MACHINING AND BEAM REMOVAL OF STATOR SHEET METAL, STATOR, CASING, VEHICLE AND PROGRAM BASED ON SUCH A METHOD

[0001] The invention relates to the field of methods for shrink-fitting stators of electrical machines of motor vehicles.

[0002] The electrical machines which equip the electromotive groups are currently equipped with so-called “active” parts, mainly consisting of a rotor and a stator.

[0003] The stator S, the fixed member of the active parts illustrated in figures 1 to 3, is generally introduced inside a main casing C, by a manufacturing process called “shrinking”.

[0004] This method makes it possible to introduce, then by differential expansion, to immobilize in rotation the stator S in the main casing C of the electrical machine.

[0005] To do this, the main casing C is first heated by induction to a temperature of the order of 200°C, which significantly increases the internal diameter in which the stator S must be housed, so that the latter can slide freely therein without any radial stress.

[0006] The main casing C is then placed vertically and immobilized by clamping on a plate P of the shrink fitting station.

[0007] An expanding mandrel then grips the stator S by its internal diameter, to come, by means of a sliding plate, to house it inside the main casing C.

[0008] The axial position of the stator S is achieved using a shoulder E, produced by machining in the main casing C.

[0009] In order to ensure a precise position of the stator S in the main casing C, the creation of a clearance or "water drop" G is necessary in the prior art.

[0010] Generally speaking, the stator S is made up of n stacks, themselves made from stacks of cut TC sheets, with a thickness of between 0.25 and 0.5 mm, and of identical diameter.

[0011] Unfortunately, this machining requires a lot of cycle time, changeover of tool and its durability.

[0012] On the other hand, when the stator S returns to ambient temperature, there may be a risk of locally deforming the stator S at the level of the stacking of the sheets constituting it.

[0013] An objective of the present invention is to remedy the defects of the prior art, and in particular to propose an easy and rapid hooping solution, limiting the risk of locally deforming the stator.

[0014] To achieve this objective, the invention proposes a method for shrink-fitting an electrical machine stator in a casing comprising a cylindrical shoulder portion and a blind receiving portion comprising a bottom wall, receiving the stator, the stator being cylindrical with a base cooperating with the receiving part, the stator comprising central and peripheral rectilinear sheets with reference to the axis of the cylindrical stator, the stator being intended to be coaxial with the casing, the stator being in a reference frame in space comprising a longitudinal axis following the central axis of the cylindrical stator and a longitudinal direction of the sheets, a lateral axis perpendicular to the longitudinal axis, and a transverse axis perpendicular to the longitudinal axis and to the lateral axis, the fretting process comprising the following steps: - a machining step in which the receiving part of the casing is machined so as to produce a rounded angle junction surface between the cylindrical shoulder part and the bottom wall; - a calibration step in which the length of the peripheral sheets along the longitudinal axis is less than that of the central sheets; and - a step of shrink-fitting the stator into the casing so that the sheets are supported on the shoulder part, and the peripheral sheets have a distance from the bottom wall of the casing

[0015] Advantageously, the invention facilitates shrink fitting because the machining of the receiving part is easier and faster than the machining of the prior art. The creation of a clearance or "water drop" G is no longer necessary thanks to the invention.

[0016] Furthermore, the invention does not require heating and cooling of the stator, which limits the risk of locally deforming the stator.

[0017] According to one variant, the junction surface has a tangent radius of between 0.5 mm and 10 mm. Preferably, the junction surface has a tangent radius of 0.7 mm.

[0018] This makes it easier to insert the stator and to apply the stress of the stator against the housing.

[0019] According to a variant, the axis of the shoulder part is parallel to the sheets.

[0020] This allows for uniform support of the sheets on the shoulder perpendicular to the longitudinal axis of the sheets.

[0021] According to a variant, the stator comprises fewer peripheral sheets than sheets power plants.

[0022] This allows for the majority of the sheets to rest on the bottom wall.

[0023] The invention further relates to a motor vehicle stator obtained by a shrink-fitting method according to the invention, the stator being cylindrical and comprising central and peripheral rectilinear sheets with reference to the axis of the cylindrical stator, characterized in that the sheets are undercut so that the length of the peripheral sheets is less than that of the central sheets; and in that the peripheral sheets are configured to have a distance from the bottom wall of the casing.

[0024] Another subject of the invention relates to a motor vehicle stator casing, obtained by a shrink-fitting method according to the invention, the casing comprising a cylindrical shoulder portion and a blind receiving portion comprising a bottom wall, configured to receive a stator, characterized in that the casing comprises a receiving portion machined so as to produce a rounded angle junction surface between the cylindrical shoulder portion and the bottom wall.

[0025] The invention further relates to a motor vehicle comprising a casing and a stator obtained by the shrink-fitting method according to the invention.

[0026] The invention will be further detailed by the description of non-limiting embodiments, and on the basis of the appended figures illustrating variants of the invention, in which: - [Fig.l] schematically illustrates a shrink fitting station implementing a shrink fitting method according to the prior art; - [Fig.2] schematically illustrates an assembly of a stator in a clearance housing according to the prior art; - [Fig.3] schematically illustrates the release casing of the method according to the prior art; - [Fig.4] schematically illustrates an assembly of a stator in a housing without clearance according to the invention; and - [Fig.5] schematically illustrates the housing without clearance of the method according to the invention.

[0027] The invention relates to a method of shrink-fitting a stator of an electrical machine of a motor vehicle.

[0028] The stator S must be inserted into a casing C. The casing C comprises a cylindrical shoulder portion E and a blind receiving portion R in continuity with the shoulder portion E. The receiving portion R comprises a bottom wall F, and receives the stator S.

[0029] The stator S is cylindrical with a base cooperating with the receiving wall R. The stator S comprises rectilinear laminations. We distinguish central laminations TC close to the central axis of stator S, and peripheral laminations TP far from said axis.

[0030] The stator S is intended to be coaxial with the casing C once inserted into the casing C.

[0031] The stator S is defined in a reference frame in space comprising a longitudinal axis X along the central axis of the cylindrical stator S and a longitudinal direction of the laminations TC, TP, a lateral axis Y perpendicular to the longitudinal axis X, and a transverse axis Z perpendicular to the longitudinal axis X and to the lateral axis Y.

[0032] In particular, the axis of the shoulder part E is parallel to the sheets TC, TP.

[0033] The proposed solution is as follows. At the end of the stator S, resting on the shoulder E, intended to ensure its axial position during the shrink-fitting operation, it is proposed to simplify the machining to a tangent radius RT which can then be directly obtained by the insert radius of the tool producing the shrink-fitting diameter of the stator S in the main casing C.

[0034] Furthermore, it is proposed to minimize the diameter of the first peripheral sheets TP constituting the stator S, so that the latter can bear on the shoulder E, the bearing surface corresponding to a predefined minimum value.

[0035] Thus, the shrink-fitting method comprises a machining step in which the receiving part R of the casing C is machined so as to produce a rounded-angle junction surface J between the cylindrical shoulder part E and the bottom wall F.

[0036] In particular, the junction surface J has a tangent radius illustrated in [Fig.5], between 0.5 mm and 10 mm, preferably 0.7 mm.

[0037] The rounded angle is inscribed in the extension of the bottom wall and the shoulder part, so that there is no clearance or drop of eu G of the prior art (illustrated in figures 2 and 3).

[0038] The shrink fitting method further comprises a de-sizing step in which the size of the peripheral laminations TP, in particular their diameters in the preferred arrangement, is reduced relative to that of the central laminations TC, so that once the stator S is inserted into the casing C, the peripheral laminations TP will not be in contact with the bottom wall F of the casing C.

[0039] In particular, a minority of peripheral TP sheets have a reduced size, in comparison with the central TC sheets.

[0040] The shrink-fitting method further comprises a step of shrink-fitting the stator S into the casing S so that the sheets TC, TP are supported on the shoulder portion E, and the peripheral sheets TP are not in contact with the bottom wall F of the casing C.

[0041] The invention further relates to the corresponding control program, as well as to a shrink-fitting installation comprising such a control program.

Claims

Claims

1. Method for shrink-fitting a stator (S) of an electrical machine in a casing (C) comprising a cylindrical shoulder portion (E) and a blind receiving portion (R) comprising a bottom wall (F), receiving the stator (S), the stator (S) being cylindrical with a base cooperating with the receiving portion (R), the stator (S) comprising central (TC) and peripheral (TP) rectilinear laminations with reference to the axis of the cylindrical stator (S), the stator (S) being intended to be coaxial with the casing (C), the stator (S) being in a reference frame in space comprising a longitudinal axis (X) following the central axis of the cylindrical stator (S) and a longitudinal direction of the laminations (TC, TP), a lateral axis (Y) perpendicular to the longitudinal axis (X), and a transverse axis (Z) perpendicular to the longitudinal axis (X) and to the lateral axis (Y),the shrink-fitting method comprising the following steps: - a machining step in which the receiving part (R) of the casing (C) is machined so as to produce a rounded-angle junction surface (J) between the cylindrical shoulder part (E) and the bottom wall (F); - a relief step in which the length of the peripheral sheets (TP) along the longitudinal axis (X) is less than that of the central sheets (TC); and - a step of shrink-fitting the stator (S) in the casing (S) so that the sheets (TC, TP) bear on the shoulder part (E), and the peripheral sheets (TP) have a distance from the bottom wall (F) of the casing (C).,

2. A method of shrinking according to claim 1, characterized in that the junction surface (J) has a tangent radius of between 0.5 mm and 10 mm.

3. A method of shrink fitting according to claim 2, characterized in that the joining surface (J) has a tangent radius of 0.7 mm.

4. A method of shrink-fitting according to any one of claims 1 to 3, characterized in that the axis of the shoulder portion (E) is parallel to the sheets (TC, TP).

5. A method of shrink-fitting according to any one of claims 1 to 4, characterized in that the stator (S) comprises fewer peripheral sheets (TP) than central sheets (TC).

6. Stator (S) of a motor vehicle obtained by a shrink-fitting method according to any one of claims 1 to 5, the stator (S) being cylindrical and comprising central (TC) and peripheral (TP) rectilinear sheets with reference to the axis of the cylindrical stator (S), characterized in that the sheets are tapered so that the length of the peripheral sheets (TP) is less than that of the central sheets (TC); and in that the peripheral sheets are configured to have a distance from the bottom wall (F) of the casing (C).

7. Motor vehicle stator casing (C), obtained by a shrink-fitting method according to any one of claims 1 to 5, the casing (C) comprising a cylindrical shoulder portion (E) and a blind receiving portion (R) comprising a bottom wall (F), configured to receive a stator (S), characterized in that the casing (C) comprises a receiving portion (R) machined so as to produce a rounded-angle junction surface (J) between the cylindrical shoulder portion (E) and the bottom wall (F).

8. Motor vehicle comprising a casing and a stator obtained by the shrink-fitting method according to any one of claims 1 to 5.

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