WO2008015147A1

WO2008015147A1 - Linear motor with a three-dimensional tooth structure

Info

Publication number: WO2008015147A1
Application number: PCT/EP2007/057696
Authority: WO
Inventors: Zeljko Jajtic; Maximilian Klaus; Christian Volmert
Original assignee: Siemens Aktiengesellschaft
Priority date: 2006-07-31
Filing date: 2007-07-26
Publication date: 2008-02-07
Also published as: DE102006035671A1

Abstract

The invention relates to an electrical machine, in particular a linear motor (1) having a primary part (2), wherein e) the primary part (2) is intended for arrangement with a secondary part (7) and the primary part (2) and the secondary part (7) are separated from one another by a first air gap (δ1), f) the primary part (2) is formed at least from a laminated core (3), with the laminated core having a multiplicity of individual laminates in layers, g) the primary part having a first width (btot), with the width (btot) extending transversely with respect to the movement direction (R) of the primary part (2), h) with the primary part having at least one flux-guiding element (10), in order to reduce the force ripple, adjacent to one or both end faces (S1, S2), with the flux-guiding element (10) having a second width (b10) which is less than the width (btot)(b10 < btot) such that the flux-guiding element (10) extends only over sub-areas of the width (btot) of the primary part (2).

Description

description

Linear motor with three-dimensional tooth structure

The invention relates to a primary part for an electrical machine, in particular a linear motor, wherein the primary ^¬ part is provided for arrangement with a secondary part and the primary part and secondary part are spaced by a first air gap of ^¬ , the primary part is formed at least from a laminated core, said the laminated core having a plurality of laminated individual sheets, the primary part has a first width which extends transversely to the direction of movement of the primary part, and at least on one or both Stirnsei ^¬ th a flux guiding element for reducing the force ripple. Furthermore, the invention relates to a linear motor with such a primary part.

Linear motors have a primary part and a secondary part. The primary part is in particular the secondary part opposite. The primary part is intended to be supplied with electric current. The secondary part has, for example Permanentmag ^¬ designated or energizable windings. Both the primary part and the secondary part have active magnetic means for generating magnetic fields.

Permanently excited linear motors have design-related force fluctuations, which adversely affect synchronization and dynamics. The force fluctuations can be partly attributed to a smaller induced stress in the peripheral coils.

In order to guide the magnetic flux of exciting field of the secondary part and the main field of the primary part, toothed plates are usually used in the active part, ie in the winding-carrying part of the motor. Between the exciter poles and the toothed structure of the main field, a magnetic ^¬ tables interaction takes place, which leads to parasitic locking forces, also called passive force ripple. The result is Vibrations, restless running and tracking errors in machining processes. Furthermore, the induced voltages, ie the electromotive forces (EMF), in the start and end coil at the end faces of the primary part due to a lack of magnetic return usually are less pronounced than in the middle coil. This has the consequence that the motor has no symmetrically induced voltage and in addition to losses of force an additional current-dependent force ripple, also called active force ripple results.

From US 6,831,379 B2, a linear motor is known, whose primary part at the end faces of the laminated core of the main ^¬ teeth having additional auxiliary teeth, said auxiliary teeth are spaced from the air gap between primary and secondary part through egg NEN additional air gap. This reduces the passive force ripple of the linear motor, ie the latching force.

A disadvantage is that although the latching force of the linear motor is reduced, the primary part has no symmetrically induced voltages in the individual windings or coils, i. There is no reduction of active force ripple.

Object of the present invention is therefore to develop a generic linear motor such that in addition to the reduction of the detent forces and a balancing of the electromotive forces takes place.

The object is solved by the features of claims 1 and 10. Advantageous developments are given in the Unteransprü ^¬ chen.

In contrast to rotating machines, linear motors naturally have end regions in which the electromagnetic part of the motor ends. Is a linear motor constructed, for example in short stator, will be apparent to the ^primary part two end portions in the area of influence of secondary partly lie. The ends of the primary interact with the secondary part in such a way that this has a significant influence on the active force ripple and the passive latching force.

The electric machine according to the invention, which is designed in particular as a linear motor, has a primary part, which is provided for arrangement with a secondary part, wherein the primary part and the secondary part are spaced from each other by a first air gap. The secondary part has a series of poles formed by permanent magnets. The

Primary part is formed from one or more laminated cores, wherein the laminated core is constructed from a plurality of sheets. The primary part has a plurality of grooves and teeth, wherein the grooves serve to receive the primary part windings or coils. The windings are designed, for example, as a three-phase winding of a three-phase network or of a three-phase alternating current. Furthermore, the primary part has a width, also called total width, which extends transversely to the direction of movement of the primary part. In addition, the primary part still has an axial length which extends in the direction of movement of the primary part.

The linear motors are formed in particular with Bruchlochwicklungen and tooth coils in the primary part, wherein the Nuttei- ment of the primary part is not equal to the pole pitch of the secondary part. For example, the ratio of Nuttei ^¬ ment to pole pitch (slot pitch / pole pitch) = 8/12, 10/12, 11/12, 13/12, 14/12, 16/12.

At least one flux guiding element for Re ^¬ production of the force ripple is in each case arranged on one or both faces of the sheets or of the laminated core. The flux-guiding e lement itself also has a width, also called the second slurry ^¬ te extending well as the total width of the primary part transversely to the direction of movement of the primary part. According to the invention, the second width of at least one flow- ^guiding element is smaller than the total width of the primary partly formed, so that the width is reduced at one or both end sides of the primary part.

The flow-guiding element or the flux-guiding elements thus do not extend over one or both end faces over the entire width of the primary part, but only over partial regions. Viewed over the entire width, the flux-guiding element therefore has gaps.

The structure of the flux guiding element, by different individual sheets which are ketiert alternately or in groups pa ^¬ be realized. Thus, for example, the middle plates on individual flux-conducting elements, resulting in a centrally arranged overall flux guiding element.

Due to the formation of only partially flux guiding elements, the adaptation between passive and active force ripple can be made according to the requirements of the linear motor.

The reduced second width of the flux guiding element can be realized, for example, in that the laminated core has different sheets. There is the possibility, not every sheet with a flux-guiding element to be sent ^¬ hen. For example, only every second sheet has a flow ^¬ leading element. In the case of one-piece primary parts, ie primary parts with only one laminated core, it is possible for each metal sheet to have only one flux-conducting element at one end region of the metal sheet. The individual sheets can then be joined together, for example, to the laminated core, that by rotating the individual sheets, the flux-guiding element is aligned once to the left or to the right. The force ripple is thus sufficiently reduced compared to the previously known possibilities.

The flux-guiding element is attached to the end faces of the single ^¬ NEN sheets or of the entire laminated core and loading can be found at or next to the respective last groove or the last wound tooth of the primary part. The flux guiding element itself carries no winding or coil.

By attaching such a flux guiding element, in addition to the reduction of the passive power ripple, also a reduction of the active force ripple is possible. The indu ^¬ ed voltages in the winding-supporting end teeth of the primary part are raised, this goal is a possible lent uniform EMF in all coils of the primary part.

The primary part has several teeth with a tooth length. The flux-guiding element may have according to its width un ^¬ terschiedliche lengths. On the one hand, the length of the flux-conducting element can correspond to the tooth length, ie teeth and flux-guiding element have the same length. On the other hand, the length of the flux guiding element may be smaller than the tooth length. In this case, the flux guiding element is separated by an additional air gap to the normal air gap between the primary and secondary part.

The choice of the length of the flux guiding element depends on the width of the flux guiding element. The wider the flux guiding element is formed over the entire width of the primary part, the shorter it can be formed. The narrower the flux guiding element is formed, the more the length of the tooth length should approach. These parameters can be used to directly influence the force ripple of the primary part.

In a further embodiment, the flux-guiding element is designed so that it partially or completely rests on a neigh ^¬ beaten winding or coil for heat exchange. This results in improved cooling of the winding or coil. Advantageously, the laminated core is integrally formed together with the flux ^¬ leading element. The flux guiding element is already formed when manufacturing the sheets, ie there is a one-piece sheet metal section, whereby a simple and cost-effective production of the individual sheets with flux-conducting elements is possible.

Laminated core with flux-guiding element can also be formed in two parts, wherein the flux-guiding element force, material or positive fit on the laminated core can be attached. The flux guiding element is attached by suitable connections, such as by gluing, screwing, hooking or by a dovetail connection to the laminated core. The flux guiding element can also be clamped or clipped to the laminated core.

Furthermore, the flux-guiding element to the or to be wound ^¬ adjacent teeth of the laminated core to a distance. Advantageously, the distance of the flux guiding element to the adjacent wound tooth is selected so that it corresponds to the pole pitch of the secondary part, so ei ^¬ ne ^highest possible flux linkage with the last coil or coils of the primary and thus a deliberate increase in the induced voltage of the last coil.

For a space-optimized design of the linear motor, a minimum width of the flux-conducting element itself and the smallest possible distance of the flux-guiding element from the or the adjacent wound teeth are sought. As a result, the optimal distance of the flux lead ^¬ the element from the respectively adjacent teeth is smaller than the pole pitch of the secondary part.

For example, if a high force of attraction between the primary and secondary part aimed at, for example for the purpose of a biasing force at an air bearing, a larger magnet facing surface of the flux guiding element before ^¬ geous. In this case, the extent of the flow- the elements selected in the direction of movement and the opti ^¬ male distance of the flux guiding element of the or the adjacent teeth is greater than the pole pitch of the secondary part.

Preferably, the air gap facing surface of the flux guiding element is rounded. The flux-guiding element has, for example, rounded corners with a predeterminable radius. This measure contributes to the reduction of the cogging forces.

The primary part of the linear motor may consist of several successively arranged in BEWE ^¬ supply direction laminated cores. Accordingly, the centrally arranged laminated cores have no flux-conducting elements, but according to the invention, only flux-guiding elements are arranged at the respective ends, that is to say the end faces of the primary part. In this case, for example, by turning a sheet with rechtsseitigem element a sheet with left-sided element, so that on the front sides of these primary parts gapless elements are present. For primary components with only one plate package, so eintei ^¬ time primary parts, flux guiding elements can be provided on each end face of the laminated core.

The flux guiding element serves to reduce the latching force over the length of the primary part and to increase the useful force of the linear motor. Furthermore, the synchronous characteristics of the engine are significantly improved.

The primary part according to the invention is preferably for a

Linear motor provided. However, the primary part can also be used in rotary machines, the stator having end regions, such as, for example, segmented tubular motors.

In the following description, further features and details of the invention will be explained in more detail in connection with the attached drawings on the basis of exemplary embodiments. tert. In this case, features and relationships described in individual variants can in principle be applied to all exemplary embodiments. In the drawings show:

1 shows a perspective view of a linear motor and a primary part with a first embodiment of a flux-conducting element; 2 shows a perspective view of a primary part with a second embodiment of the flux-guiding EIe- Mentes.

1 shows a side view of a basically ^{dargestell ¬} th synchronous ^linear motor 1, which has one or more laminated cores 3, the respective sheets are layered parallel to the plane and which form the primary part 2. The BEWE ^¬ supply direction of the linear motor 1 is attached give ^¬ by the arrow R. Windings not shown enclose the teeth 5 of the primary part 2 such that there are 6 different? ^¬ che windings in a groove. Furthermore, the linear motor 1, the secondary part 7 with the permanent magnet 8. The Se ^¬ secondary part 7 is positioned on a machine bed, not shown. The permanent magnets 8 are arranged with the pole pitch τ _M. However, the pole pitch τ _M can also be formed by electrical excitation of an excitation winding arranged in the secondary part 7. Primary part 2 and secondary part 7 are spaced apart by the air gap δ. At the end faces Si and S _{2 of} the laminated core 3 each flux-guiding elements 10 are arranged to reduce the force ripple.

Furthermore, the primary part 2 has a width b _ges , also called overall width, which extends transversely to the direction of movement R of the primary part 2.

The flux guiding elements 10 themselves also have one

Width bio on, also called the second width, which extends as well as the total width b _{tot of} the primary part 2 transversely to the ^¬ movement direction R of the primary part 2. According to the invention the second width bio of or the flow ^¬ leading elements 10 is smaller than the total width b _ges of the primary part 2 is formed so that the width b _ges at ^¬ the end faces of Si, S ₂ of the primary section 2 is in each case reduced at the.

The flux guiding elements 10 thus does not extend to the two end faces of Si, S ₂ over the entire width b _ges of the primary part 2, but only over partial areas. Viewed over the total width b _ges , the flux-conducting element 10 accordingly has gaps.

The length lio of the flux-guiding elements 10 correspond to the tooth length I5 of the remaining teeth 5.

Furthermore, the flux-guiding element 10 to the Benach ^¬ disclosed wound tooth 5 of the laminated core 3 at a distance τ _F, which is smaller than the pole pitch τ _M of the primary part.

2 shows a further embodiment of the flux-guiding element. The length lio of the flux guiding element 10 is smaller than the tooth length I5 formed. It can be clearly seen that the width bio is greater than in FIG. 1, so that a shorter design of the flux-guiding element 10 makes sense. As a result, despite the shorter length lio of the flux guiding elements 10, a sufficient magnetic flux is achieved. In this case, the flux-guiding element 10 by an additional air gap δ ₂ to the normal air gap δi between the primary and secondary part 2, 7 spaced.

Claims

claims

1. primary part (2) for an electrical machine, in particular for a linear motor (1), wherein a) the primary part (2) for arrangement with a secondary part

(7) is provided and primary part (2) and secondary part (7) by a first air gap (δi) are spaced from each other, b) the primary part (2) at least from a laminated core (3) is formed, wherein the laminated core a plurality having from GE ^¬ coated individual plates, c) the primary part has a first width (b _GES), wherein the width (b _GES) transversely (to the direction R) of the primary part (2), d) the primary part at one or both end faces (Si, S ₂ ) has at least one flux guiding element (10) for reducing the force ripple, characterized in that the flux guiding element (10) has a second width (bio) which is smaller than the width (b _ges )

(bio <bges) t such that the flux-conducting element (10) extends only over partial regions of the width (b _ges ) of the primary part (2).

Second primary part (2) according to claim 1, characterized in that the primary part (2) a plurality of teeth (5) having a tooth length (I ₅ ), wherein the length (lio) of the flux-conducting element (10) of the tooth length (I ₅ ) ent ^¬ speaks.

3. primary part (2) according to claim 1, characterized in that the primary part (2) a plurality of teeth (5) having a tooth length (I ₅ ), wherein the length (lio) of the flux-conducting element (10) is smaller than the tooth length (I ₅ ), so that the flux guiding element (10) is spaced from the secondary part by a second air gap (δ ₂ ).

4. primary part (2) according to one of claims 1 to 3, ^{¬ characterized in} that the flux ^¬ leading element (10) at least partially against an adjacent ^¬ th winding or coil (4).

5. primary part (2) according to one of claims 1 to 4, since ^{¬ characterized in} that the Blechpa ^¬ ket (3) with the flux-conducting element (10) is formed in one piece or in two parts.

6. primary part (2) according to one of claims 1 to 5, since ^{¬ characterized in} that the flux ^¬ leading element (10) non-positively, material or positively on the laminated core (3) is attachable.

7. primary part (2) according to one of claims 1 to 6, ^{¬ characterized in} that the flux ^{¬ guiding} element (10) by a predetermined distance (τ _F ) of an adjacent tooth (5) of the primary part (2) spaced apart is, wherein for the distance (τ _F ) applies: τ _F = τ _M , where τ _{M is} the pole pitch of the secondary part (7).

8. primary part (2) according to one of claims 1 to 6, ^{¬ characterized in} that the flux-guiding element (10) by a predetermined distance (τ _F ) of an adjacent tooth (5) of the primary part (2) beabstan ^¬ det is, wherein for the distance (τ _F ) applies: τ _F <τ _M or τ _F > τ _M , where τ _{M is} the pole pitch of the secondary part (7).

9. primary part (2) according to one of claims 1 to 8, as ^¬ by in that the air gap (.DELTA.I) facing surface and / or corners of the flussfüh ^¬ leaders element (10) are rounded with a predetermined radius.

10. linear motor (1) having at least one primary part (2) and at least one secondary part (7), wherein primary part (2) and secondary part (7) by a first air gap (δi) voneinan- is spaced apart, and the primary part (2) at least from the egg ^¬ nem laminated core (3) is formed, wherein the laminated core having a plurality of laminated individual sheets and the primary part least at ^¬ at one or both end faces (Si, S ₂₎ a flux guiding element (10) for reducing the force ripple, dadurchgekennzeich ^¬ net, that the linear motor (1) has a primary part (2) according to one or more of claims 1 to 9.