WO2007134566A2

WO2007134566A2 - Stepper motor comprising a movable secondary part that has a different reluctance

Info

Publication number: WO2007134566A2
Application number: PCT/DE2007/000815
Authority: WO
Inventors: Wolfgang Hill
Original assignee: Luk Lamellen Und Kupplungsbau Beteiligungs Kg
Priority date: 2006-05-17
Filing date: 2007-05-07
Publication date: 2007-11-29
Also published as: WO2007134566A3; DE112007001151A5

Abstract

A stepper motor (1) based on the reluctance principle has a primary part (2) and a secondary part (3) which is capable of moving in relation thereto. The primary part (2) has at least three pole assemblies (4), which are offset with respect to one another in the movement direction of the relative movement and each have a soft-magnetic C-core (12) with an air gap (5) and an electrical winding (7) for producing a magnetic flux which passes through the C-core (12) and the air gap (5) transversely with respect to the relative movement. The pole assemblies (4) are arranged on a holder (9) such that they are magnetically insulated from one another. The secondary part (3) has a plurality of soft-magnetic core parts (10), which are offset with respect to one another in the movement direction of the relative movement and are capable of moving into and out of the air gaps (5).

Description

Stepper motor according to the reluctance principle

The invention relates to a stepping motor according to the reluctance principle, with a primary part and a relative thereto movable secondary part.

Such a stepping motor is known from DE 29 083 A1. He has designed as a stator primary part and designed as a rotor secondary part. The primary part has a ring around the rotor rotating soft magnetic yoke, projecting radially on the inside of soft magnetic stator teeth, which are spaced apart in the circumferential direction of the primary part and wound to form magnetic poles each having a winding. The windings are energized in such a way that a magnetic traveling field is generated on the stator. The rotor has a rotatably mounted on the stator soft magnetic rotor body, on whose outer circumference rotor teeth are arranged, which interact magnetically via an air gap with the stator teeth. By appropriately driving the windings, the rotor of the stepping motor can be positioned in a number of different positions relative to the stator. However, the stepper motor still has relatively large dimensions. In addition, the production of the stepping motor and in particular the winding of the stator teeth is still relatively expensive. The stepper motor is therefore expensive.

It is therefore an object to provide a stepping motor of the type mentioned, which allows compact dimensions and is inexpensive to produce.

This object is achieved in that the primary part has at least three mutually offset in the direction of movement of the relative movement Polbaugruppen, each having a soft magnetic C-core with an air gap and an electrical winding for generating a C-core and the air gap transversely to the relative movement by passing magnetic flux have that the pole assemblies are arranged magnetically insulated from each other on a holder, and that the secondary part offset in the direction of movement of the relative movement to one another, in the air gaps and out of these movable soft magnetic core parts.

The magnetic flux thus runs transversely to the relative movement of the primary and secondary parts, whereby it is possible to provide magnetically separate pole assemblies, which are each wrapped in a simple manner with a winding in the production of the stepping motor and then connected to each other by means of the holder to the primary part can. It is even possible to produce different stepper motors with identical pole assemblies by the pole assemblies are positioned by means of different brackets differently relative to each other, for example, at different distances from each other or along circular lines with different diameters. The stepper motor is therefore inexpensive to mass-produce. Advantageously, in a stepper motor in which the primary part is designed as a stator and the secondary part as a rotor mounted movably on the stator, the pole assemblies can also be arranged asymmetrically to a rotation axis, for example only in a certain segment, to form a banana-shaped stepping motor , The stepper motor therefore allows compact dimensions. The pole assemblies can be arranged in the design of the stepper motor according to an available space.

It is particularly advantageous if the individual pole assemblies are identical. The stepper motor is then even easier and cheaper to produce.

In a preferred embodiment of the invention, the C-cores are each composed of two preferably approximately U-shaped, soft magnetic core pieces, each having a first and a second front end, the core pieces with their first ends facing each other surface adjacent to each other and wherein the air gap is formed between the mutually facing second ends. In each case, the leg of the soft magnetic core piece arranged at the air gap has a shorter length than the leg of the core piece remote from the air gap. The core pieces are preferably made of a plurality of laminated to a U-shaped ferromagnetic sheets, which are electrically insulated from each other by a surface coating. The two core pieces of the C-core are preferably identical.

It is advantageous if the individual C-cores are each coated on their outer circumference with an electrical insulating layer, and if the winding surrounding the C-core is arranged on the insulating layer. The insulating layer is preferably sprayed onto the C-cores in the production of the stepping motor. The C-cores expediently have an approximately rectangular or square cross-section. In the area of the edges of the C-core, the insulating layer may have a greater wall thickness than at locations which are spaced from the edges. The outer plates of the C-cores may be slightly smaller in size than the inner plates of the C-cores for this purpose.

Preferably, the second ends of the individual C-cores are each supported by a non-ferromagnetic support element bridging the air gap against each other. By means of the support element, the magnetic forces acting on the air gap on the second front ends can be well supported. The support element is preferably made of stainless steel or a hard plastic.

The insulating layer preferably carries metallic contact elements which are electrically connected to the ends of the winding. The pole assemblies can then be electrically connected to a drive device for the windings in the manufacture of the stepping motor after its mounting on the holder in a simple manner.

It is advantageous if the flux-conducting cross section of the C-core decreases in each case towards the air gap. This results in a greater flux density in the air gap, whereby a higher thrust force is exerted on the soft magnetic core parts of the secondary part when the windings are energized.

In a preferred embodiment of the invention, the stepping motor for detecting the relative position between the primary part and the secondary part has a measuring device for determining the inductance of at least one winding. Since the inductance of the winding changes as a function of the position of the soft-magnetic core parts relative to the C-cores, the relative position between primary part and secondary part can be determined from the measured inductance. For measuring the inductance, a high-frequency test current is preferably fed into the winding. Preferably, the inductance of all windings is measured.

It is advantageous if the measuring device for comparing a measurement signal for the inductance of at least one winding with a predetermined reference range is connected to a comparison device, and if an output of the comparison device for commutating the windings depending on the result of the comparison with a control input of a drive device for the Windings connected. When a core part approaches the air gap, the inductance value increases. At a certain threshold value, the current supply of the previous pole assembly is stopped and the previously measuring pole assembly is energized. This gives us a high level of dynamics.

The drive device is preferably designed for feeding a pulsating, pulse-phase and pulse-phase holding current into at least one winding, wherein the measuring device has means for measuring the inductance of the winding in the pulse pauses. Thus, the relative position between the primary part and the secondary part can also be measured during the holding phase in a simple manner. If a deviation occurs between The current flow of the winding can be changed in such a way that the deviation is reduced, as a result of the measured relative position and a setpoint value for the holding position. In a symmetrical arrangement, in which a middle pole assembly assumes the holding function, the inductance of the two edge pole assemblies can be measured and compared with the desired value for checking the position. If the amount of the comparison value exceeds a threshold value, it is energized. If the force of the holding pole assembly is insufficient, then additionally that edge pole can be briefly energized, whose inductance is lower.

In an advantageous embodiment of the invention, the secondary part is designed as a rotatably mounted on the primary part disc, wherein the pole assemblies are arranged on the circumference of the disc. The three pole assemblies can be arranged distributed almost anywhere on the circumference of the disc. The winding distance must only amount to an even multiple of one third of the angle between the positions to be approached with the stepper motor. A servomotor with transversal pole modules is thus very space variable executable.

The stepper motor can also be designed as a linear motor, wherein the pole assemblies are offset parallel to each other. This embodiment also allows a space-variable arrangement of the pole assemblies.

In an advantageous embodiment of the invention, the primary part is connected to a housing having a plurality of first passage openings for a fluid of a slider and the secondary part with a movably mounted on the housing, at least one second passage opening for the fluid sliding body, wherein the second passage opening by appropriate energizing the windings or alternately with the first passage opening can be brought to cover. By means of the sliding body can then be connected to a plurality of actuating cylinders in a hydraulic device, a pressure accumulator.

Embodiments of the invention are explained in more detail with reference to the drawing. Show it:

1 is a plan view of a primary part and a secondary part having reluctance stepping motor for positioning a slider,

2 shows a cross section through a first exemplary embodiment of a magnetic pole assembly of the reluctance stepping motor, FIG. 3 shows a cross section through the magnetic pole assembly shown in FIG. 2, the cross-sectional plane being at right angles to the plane of the drawing in FIG. 2 and at right angles to the plane of extension of the secondary part, and the secondary part being partially shown, FIG.

4 is a longitudinal section through a second embodiment of the magnetic pole assembly,

5 shows a cross section through the second embodiment of the magnetic pole assembly, and

FIG. 6 is a side view of the magnetic pole assembly shown in FIGS. 4 and 5. FIG.

A generally designated 1 in FIG. 1, operating according to the principle of reluctance, has a primary part 2 in the form of a stator and a secondary part 3 which is rotatable relative thereto and serves as a rotor.

The primary part 2 has three mutually offset in the direction of movement of the secondary part 3, identical construction Polbaugruppen 4, each having a soft magnetic C-core, which forms an air gap 5 between its facing end faces. The air gaps 5 are arranged side by side in a common plane and laterally spaced from each other. The extension planes of the C-cores are arranged radially to a rotation axis 6 about which the secondary part 3 is rotatable relative to the primary part 2. As can be seen in Fig. 1, the C-cores are laterally spaced from each other.

The individual C-cores are each wound with a winding 7, which is arranged in the embodiment according to FIGS. 2 and 3 with its axis parallel to the axis of rotation 6. In the embodiment according to FIGS. 4 to 6, the winding 7 has two winding coils which are each wound onto a section of the C core which is arranged approximately normal to the axis of rotation 6 with its longitudinal direction of extension.

For energizing the windings 7, these are connected to a not-shown in the drawing, known drive device. The C-core and the air gap 5 form a magnetic circuit in which the magnetic flux generated by the winding 7 is guided transversely to the direction of movement 8 of the secondary part 3, that is to say approximately radially to the axis of rotation 6. The C-cores of the pole assemblies 4 are arranged on a non-ferromagnetic holder 9, which connects the C-cores bow-shaped with each other, on the holder 9, the secondary part 3 is rotatably supported about the rotation axis 6 by means of a bearing not shown in the drawing.

The secondary part 3 has a number of mutually spaced in the direction of movement 8, in the air gaps 5 and out of these movable soft magnetic core parts 10, whose dimensions correspond approximately to those of the air gap 5. The core parts 10 are arranged on an edge region of a non-ferromagnetic carrier disk 11 which is rotatable about the axis of rotation 6 relative to the primary part. The core parts 10 are preferably cast in the material of the carrier disk 11 or encapsulated with this. In order to facilitate the positioning of the core parts 10 during the casting or injection process, they can be integrally connected to each other by a narrow web. The pitch with which the core parts 10 are arranged on the carrier disk 11, differs from the pitch with which the pole assemblies are arranged on the holder 9. The angle between which the radial center planes of mutually adjacent core parts 10 deviate therebetween deviates from the angle enclosed by the planes spanned by adjacent C cores arranged adjacent to one another.

In Fig. 1 it can be seen that the pole assemblies 4 are arranged in a relatively small segment of the carrier disk 11, which covers approximately an angle of 60 °. In the remaining segment of the carrier disk 11 no pole assemblies 4 are provided. The number of core parts 10 is greater than that of the pole assemblies 4. Nevertheless, each core part 10 can be positioned on each pole assembly 4 by appropriately energizing the windings 7.

The C-cores are each composed of two identical, approximately U-shaped, soft magnetic core pieces 12. The core pieces 12 each have a first end face 13 and a second end face 14. The core pieces 12 adjoin one another in a flat manner with their first, mutually facing front ends 13. In this case, the plane in which the first end faces 13 are arranged, approximately in the plane of extension of the carrier plate 12 is arranged. The second front ends 14 of the core pieces 12 are spaced apart by the air gap 5.

The core pieces are composed of a plurality of U-shaped sheets 15 stacked parallel to one another in a stack, which consist of a ferromagnetic material which is coated with an electrically insulating surface coating. In the embodiment of FIGS. 2 and 3 are removed from the air gap 5

Leg of the core pieces 12 inserted into a passage opening of an electrically insulating bobbin 17, which is wound with the winding 7. The bobbin 17 has an approximately U-shaped cross-section.

In the embodiment of FIGS. 4 to 6, the C-Keme are each coated on its outer periphery with an electrical insulating layer 18, which is injection-molded respectively to the C-core. On the insulating layer 18 side boundary walls are integrally formed, which form a bobbin with the insulating layer 18. The sheet stack formed from the sheets 15 has on both sides cover plates 16, which have slightly smaller dimensions than the plates 15 located between them. At the edges of the C-core, the insulating layer 18 has a greater wall thickness than at the points spaced from the edges.

As can be seen particularly clearly in FIG. 3, the core parts 10 have a phase at their end faces facing the air gap 5, which tapers the flux-conducting cross section of the C core towards the air gap 5 and thereby generates a greater flux density in the air gap 5.

In Fig. 5 it can be seen that the air gap 5 is bridged by a non-ferromagnetic support member 19 which supports the air gap facing the ends of the core parts 10 against each other and keeps at a distance.

The primary part 2 is connected to a housing of a slide, which has a plurality of first passage openings 20, shown only schematically in FIG. 1, for a fluid. The first passage openings 20 are radially spaced from the axis of rotation 6.

The carrier disk 11 has a second through-opening 21 for the fluid, which is designed as a slot which extends approximately radially with its longitudinal axis to the axis of rotation 6 of the carrier disk 11. By appropriately energizing the windings 7, the second passage opening 21 can each be brought to coincide with one of the first openings 20. At the second passage opening 21, a pressure accumulator and to the first passage opening 20 each have an actuating cylinder is connected. LIST OF REFERENCE NUMERALS

stepper motor

primary part

secondary part

pole assembly

air gap

axis of rotation

winding

movement direction

bracket

core part

carrier disc

Core piece first front end second front end

sheet

cover plates

bobbins

insulating

Support element first passage opening second passage opening

Claims

claims

1. stepping motor (1) according to the reluctance principle, with a primary part (2) and a relatively movable secondary part (3), wherein the primary part (2) at least three mutually offset in the direction of movement of the relative movement pole assemblies (4), each having a soft magnetic C-core having an air gap (5) and an electrical winding (7) for generating a C-core and the air gap (5) transversely to the relative movement passing through magnetic flux, said pole assemblies (4) to a holder (9) magnetic are arranged isolated from each other, and wherein the secondary part (3) offset in the direction of movement of the relative movement to one another, in the air gaps (5) into and out of these movable soft magnetic core parts (10).

Second stepping motor (1) according to claim 1, characterized in that the individual pole assemblies (4) are identical.

3. stepping motor (1) according to claim 1 or 2, characterized in that the C-cores are each composed of two preferably U-shaped, soft magnetic core pieces (12), each having a first end face (13) and a second end face (14 ), wherein the core pieces (12) with their first end faces (13) facing each other surface adjacent to each other and wherein the air gap (5) between the mutually facing second end faces (14) is formed.

4. stepping motor (1) according to one of claims 1 to 3, characterized in that the individual C-cores are coated on its outer circumference each with an electrical insulating layer (18), and that on the insulating layer (18) which the C-core surrounding winding (7) is arranged.

5. stepper motor (1) according to one of claims 1 to 4, characterized in that the second front ends (14) of the individual C-cores are each supported by a the air gap (5) bridging non-ferromagnetic support member (19) against each other.

6. stepping motor (1) according to one of claims 1 to 5, characterized in that the insulating layer (18) carries metallic contact elements, which are electrically connected to the ends of the winding (7).

7. stepper motor (1) according to one of claims 1 to 6, characterized in that the flux-conducting cross section of the C-core in each case to the air gap (5) decreases towards.

8. step motor (1) according to one of claims 1 to 7, characterized in that it comprises a measuring device for determining the inductance of at least one winding (7) for detecting the relative position between the primary part (2) and the secondary part (3).

9. stepping motor (1) according to one of claims 1 to 8, characterized in that the measuring device for comparing a measurement signal for the inductance of at least one winding (7) with a predetermined reference range is connected to a comparison device, and that an output of the comparison means for Commutating the windings (7) is connected in dependence on the result of the comparison with a control input of a drive device for the windings (7).

10. stepping motor (1) according to one of claims 1 to 9, characterized in that the drive device for feeding a pulsating, pulse phase and pulse phases having holding current is configured in at least one winding, and that the measuring means comprises means for measuring the inductance of the winding (7 ) in the pauses between pulses.

11. Stepping motor (1) according to one of claims 1 to 10, characterized in that the secondary part (3) as rotatably mounted on the primary part (2) mounted disc is formed and that the pole assemblies (4) are arranged on the circumference of the disc.

12, stepper motor (1) according to one of claims 1 to 11, characterized in that it is designed as a linear motor and that the pole assemblies (4) are offset parallel to each other.

13. stepping motor (1) according to one of claims 1 to 12, characterized in that the primary part (2) having a plurality of first passage openings (20) for a fluid housing of a slider and the secondary part (3) with a movable on the housing mounted, at least one second passage opening (21) for the fluid having sliding body is connected, and that the second passage opening (21) by appropriate energizing the windings (7) or alternately with the first passage opening (20) can be brought to cover.