WO2010025804A2 - Device and method for producing a rotor - Google Patents

Abstract

The invention relates to a method and a device for producing a rotor for an electric motor by means of hydraulically expanding the sleeve (5) of the electric motor, using a hydraulic device (1, 2), and then inserting the magnets (6) in the sleeve. After reducing the pressure in the interior of the sleeve (5), the inner radius of the sleeve (5) is reduced and the magnet (6) is fixed in the rotor.

Description

 Apparatus and method for manufacturing a rotor

The invention relates to a method according to claim 1 and a device according to claim 8.

DE 698 31 934 T2 describes an apparatus and a method for producing a rotor for an electric motor, in which a magnetic core is pressed into a sleeve. For this purpose, the sleeve is heated strongly, so that its diameter widens and the magnet can be introduced. It may happen that the magnet is heated so much that it demagnetizes. Furthermore, only small insertion depths of the magnet can be represented in the sleeve in this insertion process, since the magnet heats up quickly in the preheated sleeve and thus increases the diameter of the magnet. It must therefore be created consuming devices for heating and rapid cooling of the magnet.

The invention mentioned in the claims 1 and 8 is based on the problem of introducing a magnet into the sleeve of a rotor, without the sleeve or the magnet being subjected to heat, wherein the magnet has a larger outer diameter than the inner diameter of the sleeve of the rotor.

This problem is solved by the features of claims 1 and 8 according to the invention.

According to the invention, a method for producing a rotor for an electric motor is provided, wherein the rotor has a cylindrical sleeve open on both sides and a magnet, with the following method steps: The sleeve is pressurized by a hydraulic device in such a way that the inner diameter of the sleeve radially enlarged, the magnet is introduced into the sleeve and the pressure within the hydraulic device is reduced, so that the inner diameter of the sleeve is reduced radially and the magnet is fixed by the sleeve. This creates a simple, inexpensive and efficient way to bring the magnet into a sleeve without the sleeve has to be heated and cooled down. When exposed to high temperatures, the magnet is demagnetized and loses its magnetic properties. According to the invention, the magnet is not exposed to high temperatures and therefore retains its magnetic properties when introduced into the sleeve. Furthermore, the sleeve material becomes brittle when exposed to high temperatures and it can break earlier at high speeds than the sleeve according to the invention. It is also particularly advantageous that the insertion depth of the magnet in the sleeve can be chosen arbitrarily low, since the sleeve is widened over its entire length. This makes it possible to use a long compared to the length of the rotor sleeve, which also has bearing receptacles at the two ends. As a result, fewer components for the manufacture of the rotor are necessary and the rotor can be produced particularly inexpensively.

According to a particularly preferred embodiment of the invention, the hydraulic device has two separate adjacent to the openings of the sleeve pressure chambers and the pressure in the magnet at the beginning of the process-containing first pressure chamber is increased so that it is higher than the pressure in the second pressure chamber and that the magnet moves in or within the sleeve in the direction of the second pressure chamber. By generating this pressure difference, the movement of the magnet in or within the sleeve is specifically influenced and it can be controlled particularly well how far the magnet penetrates into the sleeve.

According to a further particularly preferred embodiment of the invention, the magnet moves after pressure increase within the sleeve by the hydraulic device, with vertically arranged sleeve, from a starting position along its gravity down to a final position. Thus, the magnet can be introduced into the sleeve in a particularly efficient manner and at no additional cost for other devices, since it moves in or within the sleeve, driven by its own gravitational force.

According to a further particularly preferred embodiment of the invention is during the pressurization of the sleeve by the hydraulic device of the magnet means a feed element pushed into the sleeve. This allows a particularly efficient and accurate insertion of the magnet can be ensured in the sleeve.

According to a further particularly preferred embodiment of the invention, the sleeve is introduced before the pressurization by the hydraulic device in a protective coating, so that excessive radial expansion, in particular a bursting of the sleeve is avoided. Depending on the modulus of elasticity, which characterizes the relationship between stress and strain of a solid body, or depending on the manufacturing quality of the sleeves, it is possible that the inner diameter of the sleeves increase in size when pressurized by the hydraulic device. If the inner radius of the sleeve is increased too far, then the expansion process is no longer reversible, but irreversible and the magnet can not be fixed in the sleeve. In order to obtain a defined maximum outer diameter of the sleeve below the irreversible deformation by expansion, the sleeve is inserted into the protective sheath. So it can be ensured that no sleeve takes damage during expansion and a particularly efficient production is ensured.

According to a further particularly preferred embodiment of the invention, the movement of the magnet within the sleeve is stopped by a stop. The stop ensures a constant end position of the magnet in the sleeve.

According to a further particularly preferred embodiment of the invention, the stop is firmly connected to the hydraulic device. Thus, the stop can be reused with each sleeve and the magnet is inserted equally deep into each sleeve.

According to the invention, an apparatus for producing a rotor for an electric motor, wherein the rotor has a cylindrical sleeve open on both sides and a magnet, claimed. The device is configured in such a way that the magnet is introduced into the sleeve after a pressurization with a hydraulic device, which enlarges the inner diameter of the sleeve. Subsequently, the magnet in the sleeve, after reducing the pressure within the hydraulic device and associated radial reduction of the inner diameter of the sleeve, fixed. This creates a simple and efficient way to bring the magnet into a sleeve, without the sleeve has to be heated and cooled down. When exposed to high temperatures, the magnet is demagnetized and loses its magnetic properties. According to the invention, the magnet is not exposed to high temperatures and therefore retains its magnetic properties when introduced into the sleeve. Furthermore, the sleeve material becomes brittle when exposed to high temperatures and it can break earlier at high speeds than the sleeve according to the invention. It is also particularly advantageous that the insertion depth of the magnet in the sleeve can be chosen arbitrarily low, since the sleeve is widened over its entire length. This makes it possible to use a long compared to the length of the rotor sleeve, which also has bearing receptacles at the two ends. As a result, fewer components for the manufacture of the rotor are necessary and the rotor can be produced particularly inexpensively.

According to a further preferred embodiment of the invention, the hydraulic device has two adjacent to the openings of the sleeve pressure chambers, wherein prevail in these different pressure levels. By creating this pressure difference, the movement of the magnet in or within the sleeve is selectively influenced and it can be controlled particularly well how far the magnet penetrates into the sleeve, wherein the magnet moves from the higher pressure level to the lower.

According to a further preferred embodiment of the invention, the hydraulic device has a feed element designed to advance the magnet. This element is designed to introduce the magnet a defined distance into the sleeve. Thus it can be ensured that the magnet is always positioned in the same place in or within the sleeve and that the rotors produced have the same properties.

According to a further preferred embodiment of the invention, the device has a protective casing for the sleeve, which prevents excessive radial expansion of the sleeve, in particular a bursting. Depending on the modulus of elasticity, which characterizes the relationship between stress and strain of a solid body, or depending on the manufacturing quality of the sleeves, it is possible that the inner diameter of the sleeves increase in size when pressurized by the hydraulic device. If the inner radius of the sleeve to greatly enlarged, the expansion process is no longer reversible, but irreversible and the magnet can not be fixed in the sleeve. In order to obtain a defined maximum outer diameter of the sleeve below the irreversible deformation by expansion, the sleeve is inserted into the protective sheath. Thus, a constant expansion of the inner radii of the sleeves can be secured and a particularly efficient production can be ensured.

According to a further particularly preferred embodiment of the invention, the device has a stop which defines the end position of the magnet in the sleeve. An advantage of this embodiment is that the magnet can always be introduced to a defined position in the sleeve and thus a high manufacturing quality can be achieved.

According to a further particularly preferred embodiment of the invention, the stop is firmly connected to the hydraulic device. Advantage of this embodiment is that the stop is introduced simultaneously with the hydraulic device in the sleeve and is removed at the same time with the hydraulic device after fixing the magnet. This can be made very efficient.

According to a further particularly preferred embodiment of the invention, the stop is formed as part of the inner wall of the sleeve. It is thus possible to create a defined stop in the sleeve in a particularly efficient manner. By using sleeves with different depth stops, it is possible to realize different insertion depths of the magnet in a particularly simple manner.

According to a further particularly preferred embodiment of the invention, a sealing element connects the hydraulic device and an opening of the sleeve. This ensures particularly well that no hydraulic fluid escapes during the enlargement of the inner diameter of the sleeve.

According to a further particularly preferred embodiment of the invention, the sealing element is arranged on the front side. As a result, the sealing element can be connected to the sleeve particularly quickly.

According to a further particularly preferred embodiment of the invention, the sealing element is arranged radially outside of the sleeve, wherein in the region of the sealing element, the inner diameter of the sleeve is made larger than in a middle section of the sleeve. This is advantageous in that the magnet can be easily introduced into the sleeve in the only slightly widening part of the seal. In particular, the magnet can be absorbed by this extension already of the sleeve, without the sleeve must be expanded hydraulically. As a result, a particularly good seal between the hydraulic device and the sleeve can be ensured.

According to another particularly preferred embodiment of the invention, the rotors produced are preferably used in high-speed machines. These high-revving machines are for example in electric turbocharger motors, as used in the charging of motor vehicles.

According to a further particularly preferred embodiment of the invention, the rotors produced are preferably used in high-speed machines. The rotor is long compared to the inserted magnetic core. This makes it particularly advantageous possible to use the rotor at the same time as a bearing point. As a result, it is particularly advantageous to save precise and therefore expensive to manufacture high-speed components. The rotor is also designed so that it can be stored in air.

Further advantageous embodiments and modifications of the invention will become apparent from the dependent claims and from the description in conjunction with the drawings.

Showing:

1 shows a section through an apparatus for producing a rotor for a

Electric motor according to a first embodiment, Fig. 2 shows a section through a device according to Figure 1 with incorporated

Magnet, Fig. 3 shows a section through an apparatus for producing a rotor for a

Electric motor according to a second embodiment, Fig. 4 shows a section through an apparatus for producing a rotor for a

Electric motor according to a third embodiment, Fig. 5 shows a section through an apparatus for producing a rotor for a

Electric motor according to FIG. 4 with magnet inserted, Fig. 6 is a section through an apparatus for producing a rotor for a

Electric motor according to a fourth embodiment, and

7 shows a section through an electrical machine with a built-in rotor according to the invention.

The device shown in Figure 1 for producing a rotor for an electric motor has a hydraulic device 1, 2 and a sleeve 5 of the rotor. The hydraulic device 1, 2 has a first pressure chamber 1 and a second pressure chamber 2.

The sleeve 5 is cylindrical and hollow inside. It has an upper and a lower opening on the front sides. The sleeve 5 is preferably made of a stretchable or stretchable material. In particular, a sleeve 5 made of a stretchable carbon fiber material is possible.

The hydraulic device 1, 2 used as a fluid preferably oil or water. Other fluid materials or even an embodiment of the hydraulic device as a pneumatic device are possible. The hydraulic device 1, 2 acts on the sleeve 5 with pressure, so that the inner diameter of the sleeve 5 expands radially, in particular as far as radially widening, that it is possible to move the magnet 5 in the axial direction of the sleeve 5 through the sleeve 5. For this purpose, the inner diameter of the sleeve 5 must be at least greater than the outer diameter of the magnet 6.

The hydraulic device 1, 2 is connected to the sleeve 5 via a sealing element 3, 4, the sealing element 3, 4 having a first sealing element 3 for sealing the first pressure chamber 1 and a second sealing element 4 for sealing the second pressure chamber 2. The sealing elements 3, 4 are arranged in this embodiment on the end face of the sleeve 5.

One of the two pressure chambers of the hydraulic device 1, 2, in particular the first pressure chamber 1 has inside a magnet 6, wherein the magnet 6 is formed as a rotor magnet and the magnet 6 has a north pole in a first, radially outward direction and a south pole in a second, opposite to the first radially outwardly directed direction. The magnet 6 is preferably cylindrical, so that it is able to occupy a high volume density within the sleeve. The magnet 6 is preferably formed as a rare earth magnet of, for example, samarium cobalt or neodymium-iron-boron. The outer diameter of the magnet 6 is greater than the inner diameter of the sleeve 5. Magnetic materials are often very brittle. In rotors they are exposed to high rotational speeds and thus high centrifugal forces. In order to avoid destruction of the magnet 6, it is necessary to fix the magnet in the sleeve 5 of the rotor.

After loading the sleeve 5 with pressure by the hydraulic device 1, 2, the inner diameter of the sleeve 5 increases and the magnet 6 can be introduced into the sleeve 5. In particular, it is possible for the magnet 6 to move downwards into the sleeve 5 along its force of gravity, when the sleeve 5 is in a vertical position. Alternatively, the magnet could move due to a pressure difference between the pressure in the first pressure chamber 1 and in the second pressure chamber 2 in the direction of the lower pressure having pressure chamber. Alternatively, the magnet 6 could be moved by another magnetic field within the sleeve 5.

In the pressure chamber 2, which does not contain the magnets, a stop 7 is formed, which defines the end position of the magnet 6 when inserted into the sleeve 5. After fixing the magnet 6 in the sleeve 5, the stopper 7 is removed. Alternatively, the stopper 7 may also have a pulling function, the magnet 6 being pulled into the sleeve 5 up to a defined position. Subsequently, the tension element acts as a stop 7 and it is released from the magnet 6. Alternatively, the stop can be formed within the sleeve 5 as a radial bulge. Alternatively to the stop 7, the movement of the magnet 6 within the sleeve 5 by reducing the pressure in the sleeve 5, whereby the inner diameter of the sleeve 5 is reduced, could be terminated.

Figure 2 shows the first embodiment after completion of the method. It shows the introduced into the sleeve 5 magnet 6 in its final position. It is also possible that the magnet 6 is only partially inserted into the sleeve.

FIG. 3 shows that, instead of the stop 7, an advancing element 8 can be formed in the first pressure chamber 1 containing the magnets 6, which introduces the magnet 6 with pressure into the radially widened sleeve 5 after the sleeve 5 has been acted on. The advancing element 8 can be designed, for example, as a telescopic rod be. Alternatively, a combination of feed element 8 and stop 7 may be formed, wherein the feed element 8 introduces the magnet 6 to the stop 7 in the sleeve.

In order to avoid an excessive radial enlargement, in particular a bursting of the sleeve 5, the sleeve is inserted into a protective sleeve 9 before being subjected to pressure by the hydraulic device 1, 2. Task of the protective sleeve 9 is to limit the outer diameter and thus the inner diameter of the sleeve 5. The inner radius of the protective sleeve 9 corresponds to a smaller radius than the maximum permissible outer radius of the sleeve 5 below the yield strength or below the irreversible deformation. So it can be ensured that the magnet 6 is fixed in the sleeve 5 after reducing the pressure of the hydraulic device 1, 2.

FIG. 4 shows a second embodiment of the invention. Identical elements are designated for reasons of clarity with the same reference numerals of the embodiments of Figures 1 and 3. Analogously to FIG. 1, the device has a sleeve 5, a hydraulic device 1, 2, a magnet 6 in the hydraulic device 1 and a stop 7. Unlike in the first embodiment, the sealing elements 3,4 are arranged radially outside of the sleeve 5 between the hydraulic device 1, 2 and sleeve 5.

FIG. 5 shows the magnet 6 in a fixed position within the sleeve 5.

FIG. 6 shows an alternative fourth embodiment in which, in an outer region 13 of the sleeve 5, the inner diameter of the sleeve 5 is made slightly larger than the outer diameter of the magnet 6. In the further course or in the central region of the sleeve 5, the inner diameter of the sleeve 5 is made slightly smaller than the outer diameter of the magnet 6.

FIG. 7 shows a rotor according to the invention in an electrical machine, in particular in a high-speed electrical machine, as used, for example, in electric turbochargers in motor vehicles.

The sleeve 5 is designed to be longer than the magnet 6, so that air bearing receptacles are formed at their projecting ends. The sleeve 5 is mounted axially via two air bearings 10 and 11 and via a third air bearing 12.

Claims

claims 1. A method for producing a rotor for an electric motor, wherein the rotor has a cylindrical, both sides open sleeve (5) and a magnet (6), comprising the following method steps: - The sleeve (5) is acted upon by a hydraulic device (1, 2) in such a pressure that the inner diameter of the sleeve (5) increases radially, - The magnet (6) is inserted into the sleeve (5) and - The pressure within the hydraulic device (1, 2) is reduced, so that the inner diameter of the sleeve (5) is reduced radially and the magnet (6) is fixed by the sleeve (5). 2. The method according to claim 1, characterized in that the hydraulic device (1, 2) has two separate to the openings of the sleeve (5) adjacent pressure chambers and the pressure in the magnet (6) at the beginning of the process-containing first pressure chamber (1 ) is increased so that it is higher than the pressure in the second pressure chamber (2) and that the magnet (6) moves in or within the sleeve (5) in the direction of the second pressure chamber. 3. The method according to claim 1, characterized in that the magnet (6) after pressure increase within the sleeve (5) by the hydraulic device (1, 2), with vertically arranged sleeve (5), from a starting position along its gravity downwards moved to a final position. 4. The method according to claim 1, characterized in that during the pressurization of the sleeve (5) by the hydraulic device (1, 2) of the magnet (6) by means of a feed element (8) in the sleeve (5) is pushed. 5. The method according to any one of the preceding claims, characterized in that the sleeve (5) is introduced before the pressurization by the hydraulic device (1, 2) in a protective sheath (9), so that an excessive radial expansion, in particular a bursting of the sleeve (5) is avoided. 6. The method according to any one of the preceding claims, characterized in that the movement of the magnet (6) in or within the sleeve (5) by a stop (7) is terminated. 7. The method according to claim 6, characterized in that the stop (7) with the hydraulic device (1, 2) is firmly connected. 8. A device for producing a rotor for an electric motor, wherein the rotor has a cylindrical, both sides open sleeve (5) and a magnet (6), characterized in that the device is designed such that the magnet (6), after a enlarge the inner diameter of the sleeve (5) Pressurization by means of a hydraulic device (1, 2), in the sleeve (5) is introduced and in the sleeve (5), after reducing the pressure within the Hydraulic device (1, 2) and associated radial reduction of the Inside diameter of the sleeve (5) is fixed. 9. Apparatus according to claim 8, characterized in that the hydraulic device (1, 2) has two pressure chambers (1, 2) adjoining the openings of the sleeve (5), wherein different pressure levels prevail in them. 10. The device according to claim 8, characterized in that the hydraulic device (1, 2) for advancing the magnet (6) formed feed element (8). 11. Device according to one of claims 8 to 10, characterized in that the device comprises a protective sheath (9) for the sleeve (5), which prevents excessive radial expansion of the sleeve (5), in particular a bursting. 12. Device according to one of claims 8 to 11, characterized in that the device has a stop (7) which defines the end position of the magnet within the sleeve (5). 13. The apparatus according to claim 12, characterized in that the stop (7) with the hydraulic device (1, 2) is firmly connected. 14. The apparatus according to claim 12, characterized in that the stop (7) is formed as part of the inner wall of the sleeve (5). 15. Device according to one of claims 8 to 14, characterized in that a sealing element (3, 4) connects the hydraulic device (1, 2) and an opening of the sleeve (5). 16. The apparatus according to claim 15, characterized in that the sealing element (3, 4) on the end face of the sleeve (5) is arranged. 17. The apparatus according to claim 15, characterized in that the sealing element (3, 4) is arranged radially outside of the sleeve (5), wherein in the region of the sealing element (3, 4), the inner diameter of the sleeve (5) is made larger as in a central region of the sleeve (5). 18. Device according to one of claims 8 to 17, characterized in that the device is suitable for the production of rotors in high-revving machines. 19. The method according to any one of claims 1 to 7, characterized in that the method for the production of rotors for high-revving machines is applied.