EP2622720A2

EP2622720A2 - Balanced rotor for a rotary machine and method for balancing a rotor

Info

Publication number: EP2622720A2
Application number: EP11740888.0A
Authority: EP
Inventors: Steffen Blum; Stephan Weissphal; Markus Minnermann
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2010-09-29
Filing date: 2011-07-28
Publication date: 2013-08-07
Also published as: DE102010041599A1; WO2012052202A2; WO2012052202A3; CN103222163A; US20130257189A1

Abstract

A balanced rotor and a method for balancing a rotor for a rotary machine, such as for example an electric motor, are described. The rotor (1) has at least one disc-shaped rotor body (9), which has magnetic elements (13) in the region of an outer circumference (11). A plurality of off-centre clearances (21) are also formed in the rotor body (9). In order to balance the rotor body (9), a rivet (23), for example in the form of a blind rivet or a Rivscrew® rivet, may be introduced and pressed into one or more of these clearances (41). The rivet (23) is thereby introduced directly into the rotor body (9). There is no need for an additional annular balancing disc. This makes simple, low-cost and reliable balancing of the rotor possible.

Description

DESCRIPTION

TITLE

Balanced rotor for a rotary machine and method for balancing a rotor

FIELD OF THE INVENTION

The invention relates to a balanced rotor for a rotary machine. The invention further relates to a method for balancing a rotor for a rotary machine.

PRIOR ART Rotating bodies, such as rotors of rotary machines, should be balanced prior to start-up, especially if they are to be operated at high speeds. Well-balanced rotors can be important for bearing and shaft life and for sound radiation and vibration transmission to the environment.

Rigid rotors can usually be balanced by adding or reducing masses at a certain distance from the rotation axis in one or more planes which are arranged perpendicular to a rotational axis of the rotor. In this context, a distinction can be made between static imbalances and dynamic imbalances. For static imbalances, the center of gravity of the rotor is not on the axis of rotation. A static unbalance can ideally be eliminated with just one balance mass. In the case of dynamic imbalances, which are also referred to as moment imbalances, the center of gravity of the rotor is indeed on the axis of rotation, but the principal axis of inertia is not parallel to the axis of rotation. For balancing this is usually required several balancing masses on must be distributed at least two levels, so that the main axis of inertia of the rotor including the balancing masses is rotated so that it then lies on the axis of rotation.

Conventionally, rotatable bodies, such as rotors for high speed rotary machines, are balanced by placing additional balancing ring disks. The Wuchtringscheiben are usually arranged at the two opposite end faces of the rotor and rotate during operation of the rotor with the rotor. In so-called additive balancing, e.g. Lead weights are attached to the Duchtringscheibe to compensate in this way an imbalance of the rotor can. Alternatively, bores can be introduced into the co-rotating rolling disk, whereby a center of gravity of the co-rotating disk is displaced and in turn an imbalance of the rotor can be compensated. This is called subtractive balancing.

DISCLOSURE OF THE INVENTION

There may be a need for a balanced rotor or a method of balancing a rotor, where balancing can be achieved with reduced labor and expense.

Such a need can be met by the subject matter of the independent claims. Advantageous embodiments are defined in the dependent claims.

According to a first aspect of the present invention, a balanced rotor for a rotary machine is described. The balanced rotor has at least one disk-shaped rotor body with magnetic elements along a circumference of the rotor body. In the rotor body a plurality of eccentric recesses is formed. In at least one of these recesses a rivet is inserted and pressed.

In a second aspect of the invention, a method for balancing a rotor for a rotary machine is described. The method in this case comprises providing the rotor with at least one disk-shaped rotor body with magnetic elements along a circumference of the rotor body and a multiple rotor body. number of eccentric recesses in the rotor body, determining an imbalance of the rotor and then pressing at least one rivet in one of the eccentric recesses such that an imbalance of the rotor is at least partially compensated.

The above aspects of the invention or its embodiments may be considered to be based on the following ideas:

In traditionally balanced rotors for rotary machines usually in addition to the actual rotor, which carries the magnets that are necessary for the motor or generator drive of the rotor within the rotary machine, provided on at least one or mostly both end faces of the rotor, a separate balancing ring , In this balancing ring weights or recesses can be introduced to balance the entire unit of rotor and Duchtringscheibe. Since this Wuchtringscheibe is a separate, additional component, their provision means additional labor and cost. In addition, the additional Wuchtringscheibe a mass that, since it must rotate with the rotor contributes to an increased moment of inertia of the entire rotating component. In addition, in conventional additive balancing in which one or more pins in a separate balancing ring disk provided with corresponding holes are depressed, it may be necessary to form the balancing ring disk from a material which sufficiently maintains the preload with which the pins held in the holes of the Wuchtringscheibe can ensure.

In contrast, should be dispensed as possible with the balanced rotor presented here on separate Wachttringscheiben.

For this purpose, the rotor-forming mostly disc-shaped rotor body are designed accordingly that additional weights can be arranged for balancing directly in them. In this case, the rotor bodies can be formed, for example, in the form of a circular disk or with another non-circular outer geometry, such as polygonal, flower-like, etc. Such a disk-shaped rotor body usually carries magnetic elements, such as permanent magnets or electromagnets, along its circumference, so that an externally acting magnetic field in the engine operation, a torque on the rotor can exercise the rotor in rotation movement or in generator mode during rotation of the rotor, a changing magnetic field can generate a voltage in surrounding coils .. The magnetic elements can, for example, along the circumference of the rotor body on the lateral surface by means of suitable methods such as Sticking to be attached. Alternatively, the magnetic elements may be arranged in a so-called buried manner within the rotor body, wherein in the rotor body in the vicinity of the outer periphery cavities are provided, in which the magnetic elements can be introduced and held therein. In principle, a rotor can be formed with a single disk-shaped rotor body. In practice, however, rotors are usually formed with a plurality of disc-shaped rotor bodies, wherein the individual rotor bodies are usually arranged along a rotation axis next to one another on a shaft and pressed with this.

In the rotor described here, in addition to the magnetic elements, eccentric recesses are formed in the rotor body. These eccentric recesses are arranged radially at a distance from the axis of rotation of the rotor body. They are designed so that additional mass can be absorbed in them, in this way the focus of the

To be able to shift rotational body and thus provide for a balance of the rotor body. In order to be able to compensate for different types and dimensions of imbalances, a plurality of eccentric recesses is provided. For example, 8 or more, preferably 16 or more eccentric recesses may be provided. The recesses may be formed along a concentric with the rotor body circle. In other words, the radial distance of all the recesses to the axis of rotation of the rotor body can be the same. The recesses may be arranged equidistantly along the concentric circle. Preferably, the recesses in the rotor body are arranged and dimensioned such that their common center of gravity lies on the axis of rotation of the rotor body.

In the balanced rotor, a rivet is arranged in at least one of the recesses provided in the rotor body or the plurality of rotor bodies. A rivet is a plastically deformable, mostly substantially cylindrical element. ment. Rivet connections are conventionally used mostly for joining parts such as sheets and are standard components that can be provided in large quantities and thus manufactured at low cost.

Rivets can be provided in a variety of materials and configurations. For example, there are rivets of steel, copper, brass, aluminum alloys, plastic and titanium. There are solid rivets, blind rivets, punch rivets, semi-hollow rivets, etc. known.

Components in which rivets are to be introduced and pressed with them or which are to be connected to one another by means of rivets, have to have recesses, for example in the form of bores. These recesses should have a slightly larger diameter than the rivet. In or through these recesses, the rivet is pushed in or pushed through.

The rivet can protrude beyond a surface of the component. The rivet can be machined so that a protruding end of the rivet is formed into a so-called closing head, which rests against surfaces of the component and thus holds the rivet to the component. Alternatively, the rivet can be processed in such a way that its shank arranged in the recess thickened, ie increases in diameter, so that an outer circumference of the rivet shank is firmly pressed against an inner circumference of the recess and the rivet is thus pressed into the recess.

Rivets can have the advantage over screws, that in the recesses in the component no thread needs to be introduced. In addition, an insertion and fastening of the rivet is usually possible quickly and easily. The rivet may initially have a smaller cross-section than the recess and thus be easily inserted into the recess. Then, the rivet can be braced with suitable tools in the recess and thus secured by its cross-section is increased. In the fastened state, the rivet is pressed into the recess in a force-fitting and / or form-fitting manner.

By introducing and pressing the rivet in the recess provided in the rotor body itself, the rivet can be reliably fixed in the rotor body. be taken. Since the rivet has its own weight, which is accommodated in the eccentric recess and can lead to an additional moment when the rotor rotates, a balancing of the entire rotor can be achieved with the aid of the pressed-in rivet. The recesses in the rotor body are preferably arranged with respect to their positioning and formed with respect to their shape and arranged in at least one of the recesses at least one rivet is formed with respect to its shape and weight such that an imbalance of the totality of the rotor body and rivet is smaller as an imbalance of the rotor body alone. In other words, due to the rivet pressed into the recess, an imbalance of the rotor body can be reduced, wherein the shape, position and weight of the rivet can be adapted to the imbalance to be compensated.

For balancing the rotor, an unbalance of the rotor without the rivet can first be determined, for example, by measurement or based on empirical values. Based on the determined imbalance, it can be analyzed how a suitable counter imbalance can be created by inserting rivets of appropriate weight in suitable locations in recesses within the rotor. In this way, a balancing of the rotor with a balancing quality of G 2.5 or even G 1 can be achieved. The balancing quality can according to the

Standard ISO 1940 be defined.

As rivets to be introduced into the recesses so-called blind rivets can be used. A blind rivet is a special form of rivet that only requires access to one side of the component to be riveted. Of the

Blind rivet can be fixed with a special blind rivet. Typically, the blind rivet in addition to the actual hollow rivet body with head on the front of a longer, elongated mandrel head with the rear rivet end, which is provided with a predetermined breaking point. So-called magazine rivets do not have their own mandrel but the mandrel is integrated in the tool which can be used to fix the blind rivet. Blind rivets are sometimes referred to as POP rivets. It needs not necessarily be provided at the rear end another head.

When blind riveting is a joining process or press-fitting of only one, outer side of the component. The blind rivet is inserted into the recess. leads. Subsequently, the protruding on the head mandrel is pulled out with a blind rivet. This leads to a compression and thus an expansion or increase in diameter of the rivet in the recess. At the end of the process, the mandrel typically breaks off at the predetermined breaking point within the rivet body and no longer protrudes from the rivet. Blind rivets are manufactured for a wide variety of applications and are therefore manufactured in large quantities standard components that can be provided very inexpensively. The use of blind rivets for balancing a rotor therefore allows a very cost-effective balancing method.

Rotor body for fast rotating rotors permanently excited synchronous machines, as used for example for electric and hybrid drive vehicles are often formed from a plurality of concentrically stacked lamella plates. In this case, several thin sheets are stacked into a laminae package and joined together, for example by pressing. The individual sheets can be easily brought into shape by punching operations. For example, the recesses into which buried magnets can be inserted, or the recesses, which, as described herein, are to receive the balancing rivets, can be produced by punching out suitable areas from the slat plate. Since the punching of the recesses always certain geometrical deviations occur due to manufacturing tolerances, is found in the recesses formed in the stack of stacked lamellae for balancing rivets usually inevitably a certain offset of the punched in the individual laminations recesses. This results in an uneven, for example, tooth-shaped structure on the surface of the recesses in a direction parallel to the axis of rotation of the rotor body.

In such a recess provided with an uneven surface, advantageously, a rivet also provided with an uneven surface can be introduced. Due to the uneven surface of both the recess and the rivet can lead to a positive connection of rivet and recess. Thus, a very good hold of the rivet is ensured in the recess. As a rivet with a special, uneven surface, a rivet with a screw geometry can be used. Such rivets are also referred to as Rivscrew® rivets. Especially with rotor bodies formed with lamellae packages, such helical rivets can stably mesh into the recesses within the laminae packages, also provided with an uneven surface, due to their "serrated" surface, despite slightly increased manufacturing costs for such helical rivets compared to simple blind rivets their use be justified because of the better grip.

The rivets often consist of a different material than the rotor body. In order not to disturb the magnetic field generated by the magnetic elements provided along the circumference of the rotor body, it may be advantageous for the recesses in which the rivets are to be arranged to have a spacing of at least 5 mm, preferably at least 7 mm of the magnetic elements to arrange. The recesses may be located radially inside the magnet elements in the rotor body. Due to the sufficient distance of the recesses from the magnetic elements, a negative influence on the magnetic flux generated by the magnetic elements is avoided.

It is noted that thoughts on the invention are described herein in the context of both a balanced rotor assembly and a method of balancing a rotor for a rotary machine. It is clear to a person skilled in the art that the individual features described can be combined with one another in various ways so as to also lead to other embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will be described below with reference to the accompanying drawings.

Fig. 1 shows a cross-sectional view of a balanced rotor for a rotary machine according to an embodiment of the present invention. Fig. 2 shows a cross-sectional view of a balanced rotor for a rotary machine according to another embodiment of the present invention.

3 shows a plan view of a rotor body for a balanced rotor according to an embodiment of the present invention.

4 shows an enlarged view of a recess for receiving a rivet in a rotor body for a rotor according to an embodiment of the present invention.

The figures are only schematic and not to scale. EMBODIMENTS OF THE INVENTION

Fig. 1 shows a rotor 1 for a rotary machine such as an electric motor or a generator. On a shaft 3, a plurality of disk packs 5 are arranged in a direction along a rotation axis 7 in succession and pressed with the shaft 3. Each of the disk packs 5 consists of a plurality of stacked laminations 19. The plurality of disk packs 5 together form a circular disk-shaped rotor body 9. A plan view of an end face of the rotor body 9 is shown in FIG.

In the vicinity of the outer periphery 1 1 of the rotor body 9 a plurality of magnetic elements 13 in the form of cuboid permanent magnets 15 are arranged. The magnetic elements 13 are introduced in likewise cuboidal recesses 17 in the rotor body 9 and fixed in these by pressing or gluing.

In the outermost disk pack 5 of the rotor body 9, a plurality of recesses 21 are further provided. The recesses 21 are arranged at a certain distance s from the center of the rotor body, through which the axis of rotation 7 extends, and thus positioned eccentrically. The recesses 21 are further spaced a distance d from the recesses 17 for the magnetic elements. In the example shown, the rotor body 9 has an outer diameter of 83 mm. The distance s of the recesses 21 from the center is 25 mm. The distance d of the recesses 21 from the recesses 17 is 7 mm. There are twenty recesses 21 along an axis concentric with the axis of rotation 7 circular circle arranged equidistantly. Each of the recesses 21 has a circular cross section with a diameter in the range of 1-5 mm. A depth of the recess 21 in the direction parallel to the rotation axis 7 may be in the range of 5-20 mm. In the recesses 21 blind rivets 23 can be introduced and pressed therein. In a balancing process, first the unbalance of the entire rotor 1 is determined. On the basis of the determined imbalance can be calculated at which positions counterweights should be introduced into the rotor 1. Rivets of suitable weight can then be pressed into a corresponding recess 21 at these positions. The rivets can be provided with weights in the range of 0.1-2 g, preferably in the range of 0.35-1.5 g.

In the embodiment shown in FIG. 1, the additive balancing weight is provided in the form of a blind rivet 23. The rivet is introduced from outside into the disk set 5 located in the figure on the left edge after assembly of the disk packs 5 on the shaft 3 and pressed. The desired position of the balance weight is determined using a balancing system. If the weight of a single rivet is insufficient, a rivet can be additionally attached elsewhere. There are a variety of in the

Disc pack 5 punched circular hole recesses 21 available. It can blind rivets 23 different weights are used.

This method offers advantages due to the low cost of the balancing weights, since the blind rivets used for this purpose are standard parts that are used in large quantities

Quantities are produced at low cost. In addition, the riveting process is proven and reliable. It is a clean process that precludes fouling of the rotor, for example due to shavings from balancing bores, since the recesses 21 already come into contact with each other during the manufacturing process of the disk packs 5, for example by punching can be formed and not only after assembly of the disk packs 5 must be introduced to an entire rotor.

In the embodiment shown in FIG. 2, special rivets 25 with an uneven surface 27 are made in recesses 21 in the rotor 1. For this purpose, so-called RivscrewO rivets are used. These RivscrewO rivets have a screw thread 33 on a lateral surface of the otherwise cylindrical shaft 31. As shown enlarged in FIG. 4, the disk packs 5 have a plurality of individual laminations 19. The recesses 21 are punched into the individual lamella plates 19 prior to the assembly of the lamella plates 19 to the plate packs 5. Due to manufacturing tolerances, there are regularly small deviations with regard to the position and size of the punched out areas. This results in the composite disk set 5 to the fact that the recess 21 has no flat surface, but, caused by the inevitable offset during punching, forms a tooth-shaped structure. In this tooth-shaped structure of the recess 21, the tooth-shaped structure of the helical outer surface of the Rivscrew® rivet 27 can engage well and lead to a positive compression.

It should be noted that although only one rivet 23, 27 is shown in the figures, a plurality of rivets may be arranged in the rotor body 9. Although only one rivet is shown in a disk pack 5 at the extreme left edge of the rotor body 9, rivets can also be accommodated in a disk set at the extreme right edge or in disk packs 5 at both arranged on the opposite edges of the rotor body 9 disk packs 5.

With the proposed balanced rotor or the method for balancing a rotor, a cost-effective, yet precise balancing with a balancing quality of, for example, better than G 2.5 can be achieved.

Claims

claims

Balanced rotor (1) for a rotary machine, comprising:

at least one disc-shaped rotor body (9) with magnetic elements (13) along a circumference (11) of the rotor body (9);

characterized in that

the rotor body (9) has a plurality of eccentric recesses (21),

wherein in at least one recess (21) a rivet (23) is arranged.

Rotor according to claim 1, wherein the recesses (21) are arranged and formed in such a way and in at least one recess (21) arranged at least one rivet (23, 27) is formed such that an imbalance of the totality of the rotor body (9) and rivet (23, 27) is smaller than an imbalance of the rotor body (9) alone.

Rotor according to one of claims 1 or 2, wherein the rivet (23, 27) is a blind rivet (23).

Rotor according to one of claims 1 to 3, wherein the rotor body (9) with a plurality of concentrically stacked laminations (19) is formed.

Rotor according to one of claims 1 to 4, wherein the rivet (27) has an uneven surface.

Rotor according to one of claims 1 to 5, wherein the rivet (27) has a screw geometry.

Rotor according to one of claims 1 to 6, wherein the at least one rivet (23, 27) in the recess (21) non-positively and / or positively a pressed.

Rotor according to one of claims 1 to 7, wherein the recesses (21) along a with the rotor body (9) concentric circle are formed.

Rotor according to one of claims 1 to 8, wherein the recesses (21) of the magnetic elements (13) with a distance (d) of at least 5mm are arranged. 10. A method of balancing a rotor (1) for a rotary machine, the method comprising the steps of:

Providing the rotor (1) with at least one disc-shaped rotor body (9) with magnetic elements (13) along a circumference (11) of the rotor body (9) and a plurality of eccentric recesses (21) in the rotor body (9);

Determining an imbalance of the rotor (1);

Pressing at least one rivet (23, 27) into one of the eccentric recesses (21) such that an imbalance of the rotor (1) is at least partially compensated.