DE102011051020B4 - DC linear actuator - Google Patents

Abstract

Direct current linear drive comprising - a rotor with a movable coil (09), - a linear guide made of a non-magnetizable material on which the rotor is guided, with a guide (06) and a carriage (08) movable thereon for receiving the coil (09) a stator, on which a magnetic circuit is formed, with a central yoke (01), which extends through a cross-sectional area surrounded by the coil (09) of the rotor, two parallel outer yokes (02), which each have permanent magnets (04) wear, which are arranged diametrically opposite to the middle yoke (01); the linear guide being mounted on the middle yoke (01) and also extending through the cross - sectional area surrounded by the coil (09), characterized in that the central yoke (01) has a rectangular cross section, and in that the linear guide abuts against the planar upper side of the middle yoke (01) is directly coupled.

Description

The invention relates to a DC linear drive according to the preamble of claim 1. Such so-called electrodynamic linear motors can be used in particular for the smaller power range with relatively short travel distances. Their advantages lie above all in the high dynamics and the high producible force.

Generic DC linear motors or drives are often referred to as voice coil, voice coil or moving coil actuators or motors. Their principle of action - the electrodynamic principle - has been known for a long time. In this case, a force (Lorentz force) acts on a current-carrying coil, which is located in a magnetic field. The force and direction of movement of the rotor is directly dependent on the direction and magnitude of current flow through the coil.

From the US 4 808 901 A is a generic linear motor with moving coil known in which the yoke is arranged with the coil laterally adjacent to the linear guide of the movable platform. The coil is connected to the platform at a lateral projection.

In the DE 10 2009 018 866 A1 a linear drive of the same type is disclosed in which the movable carriage is connected via a coupling part with the coil and the yoke and the carriage are also arranged side by side in the direction of movement of the coil.

In the cited prior art, it is disadvantageous that the positive guidance of the carriage must absorb a tilting moment, since forced guidance and the origin of the force are spaced apart from one another. Accordingly consuming is the dimensioning of the forced operation. Precision drives in particular depend on the high accuracy of the positioning.

From the DE 10 2006 052 364 A1 a generic linear drive is known in which a main guide and a secondary guide of the rotor are provided as Wälzkörperführungen. Due to the large distance between the two guides from each other high accuracy of movement and securing the rotor against twisting and tilting is achieved. This variant is relatively complicated and expensive to manufacture due to the two separate rolling element guides.

In synchronous or asynchronous linear motors, the primary part is usually designed as a guide rail for the secondary part (runners).

From the DE 689 09 429 T2 a linear motor for high-precision positioning of an optical reading unit is known, in which the middle yoke, which is enclosed by two wound on a bobbin coils is divided into two spatially separated, parallel yokes, which also serve as a guide for the coils by a Having guide groove which penetrate a correspondingly shaped passage of the bobbin, wherein between the guide groove and the bobbin rolling elements are provided. The yokes are thus used to form the magnetic circuit and to guide the bobbin, whereby a separate guidance of the bobbin can be omitted, thereby a high dynamics of the drive is achieved. Different yoke cross sections in the magnetic circuit are problematic in the dimensioning of the motor and in the production of the yokes.

The JP H11-55 925 A describes a linear actuator in which a bobbin is guided with a coil and a holding device on a central yoke. The holding device has a linear guide, which comprises the central yoke as a main guide and a second guide rail as an auxiliary guide.

From the JP S62-34 745 A a linear guide for a positioning table is known in which two parallel linear drives are provided, in which the yoke simultaneously forms the guide unit at the same time. The bobbins are each guided on the yoke by means of compressed air at a distance from the yoke.

The JP H08-80 028 A relates to an electromagnetic conveying mechanism, for example for curtains or doors, in which a coil is displaceable along a long yoke. A bearing should reduce the friction between the coil and the yoke.

From the DE 29 08 413 A1 For example, a linear actuator for a magnetic disk storage with a cantilevered coil is known in which the linear guide for the carriage is guided by means of ball bearings on a precision rod which is arranged within the cross-sectional area of the coil at the central yoke. As a further guide elements guide rails formed by side parts are required, which are arranged outside of the coil cross-section.

The object of the invention is based on the DE 29 08 413 A1 It is to improve a DC linear motor to the effect that a simplified and inexpensive realizable leadership of the rotor and a driven carriage is made possible.

The object is achieved by a DC linear drive with the features of claim 1.

A DC linear drive according to the invention comprises a stator which is formed by a magnetic circuit with permanent magnets. The magnetic circuit comprises a middle and two outer yokes, which are arranged parallel to each other. The outer yokes are angled at their ends to make a magnetically conductive connection to the middle yoke. This yoke assembly is similar to an "8", which is drawn in width. At the outer yokes facing the middle yoke, permanent magnets are arranged, which are magnetized in the direction of their thickness.

A coil is in a conventional manner as a runner on the middle yoke, this enclosing, arranged and guided in a linear guide.

According to the invention, the linear guide is coupled directly to the middle yoke. It is enclosed by the coil. The coil thus encloses the middle yoke and the linear guide. The linear guide comprises a movable carriage and a guide for the carriage. The carriage serves to accommodate the spool and receiving an adapter for a support carriage.

Thus coil guide and support slide guide are placed in the coil interior such that the Lorentz forces acting on the coil, also centrally on the carriage and thus act on the support carriage. Tilting is therefore minimized. In an advantageous embodiment, carriage and adapter are made in one piece.

The advantages of the invention are in particular to be seen in the fact that the guides for the coil and the supporting carriage driven by the coil are arranged centrally to the Lorentz force acting on the coil, whereby no tilting moment can arise. In addition, the middle yoke in addition to the leadership function for coil and support carriage also assumes a support function for the carriage and support carriage, which is why the previously necessary frame plate, which accommodated both functional units, can be omitted. Since the yoke parts of the magnetic circuit are connected directly to the middle yoke and the guide arranged thereon, a compact space-minimized linear drive unit is formed.

Advantageous embodiments of the DC linear actuator according to the invention will become apparent from the dependent claims.

In a preferred embodiment of the invention, the parts of the linear guide are made of a non-magnetizable material. Particularly suitable for this are light metals and plastics. But also ceramic materials can be used, for example, for rolling elements in circulation guides. Such a linear guide does not affect the magnetic circuit and the regulation of the coil current.

The linear guide itself can be designed in all known ways. Both purely mechanical guides with rolling or plain bearings, but also hydrostatic or hydrodynamic bearings, z. Eg air bearing for the car. The corresponding design can easily be made by a person skilled in the art.

In the simplest case, the car on a guide, z. For example, be guided slidingly a rail. Alternatively, the use of a recirculating ball bearing or ball roller guide is possible.

The yoke parts preferably have a rectangular or square cross-section. In these embodiments, inexpensive flat magnets can be used. In addition, the connection of the linear guide is facilitated to the middle yoke, as a flat top of the yoke is available as a guide base. In addition, rectangular Jochquerschnitte are easy and inexpensive to produce.

Due to the simple possibility of connecting the linear guide to the yoke cross section, the linear guide can also be made interchangeable in modified embodiments and thus offers the possibility of being able to use various suitable commercially available guide assemblies with the system merely by changing the coil dimensions.

In any case, the drive can be easily adapted to different application scenarios by the configuration of the linear guide and the corresponding dimensioning of the coil. The dimensioning of the coil and thus the determination of force, speed and acceleration of the drive prepare the expert no difficulties. The coil winding may be designed as a copper or aluminum winding. The use of aluminum wire for the coil winding results in significant advantages in terms of the total weight of the drive and thus a higher achievable acceleration over conventional linear drives.

In a further preferred embodiment, the DC linear drive also includes a displacement measuring system in order to enable accurate positioning and possibly position regulation of the carrier carriage. The displacement measuring system preferably comprises a distance measuring ruler with a incremental scale and a displacement sensor which may be implemented in any known manner. Optical path measuring methods which are known to the person skilled in the art have proven to be particularly suitable. But also inductive, capacitive or tactile measuring systems have proven themselves and can be used depending on the measuring task. The scale can be easily coupled to the cart or adapter.

In order to park the car at a shutdown of the stream in a safe position, a determination of the car can be done in a parking position. For this purpose, a switchable magnet is particularly suitable. The switchable magnet preferably releases a locking mechanism in the de-energized state, in which a positive-locking element, for example a latch, engages in a recess in the carriage or in the adapter plate. So the car is prevented from any unwanted movement, as long as no electricity flows. As a result, an uncontrolled impact of the car at an end position with its possibly sensitive functional elements is safely prevented during power off. Such emergency braking systems are known in various embodiments. Their design and dimensioning will not cause any difficulty to the skilled person.

A particularly preferred embodiment of the invention is illustrated in the drawing and will be explained in more detail below.

• 1: eine perspektivische Darstellung eines erfindungsgemäßen Gleichstromlinearantriebes;
• 2: eine Draufsicht auf den in 1 dargestellten Gleichstromlinearantrieb;
• 3: eine Schnittdarstellung entlang der Schnittlinie B-B gemäß 2;
• 4: eine Schnittdarstellung entlang der Schnittlinie A-A gemäß 2.

Show it:

• 1 a perspective view of a direct current linear drive according to the invention;
• 2 : a top view of the in 1 illustrated DC linear actuator;
• 3 : a sectional view along the cutting line BB according to 2 ;
• 4 : a sectional view along the cutting line AA according to 2 ,

In 1 An inventive DC linear drive - shown in a perspective view. The 2 to 4 show different views or sectional views of the same DC linear actuator.

The DC linear actuator has in a conventional manner a stator which forms a magnetic circuit. The stator includes a middle yoke 01 and two parallel outer yokes 02 each with angled ends, the middle yoke 01 facing and attached to this. This attachment is preferably positive and non-positive by means of Schraubstiften 03 , Other types of connections by means of extensions, recesses or mating or threaded holes for pins and screw elements are possible here.

At the middle yoke 01 facing inner sides of the outer yokes 02 are permanent magnets 04 preferably attached by gluing. The permanent magnets 04 are magnetized along their thickness and extend over the entire travel range of the drive.

At the middle yoke 01 is coupled to a continuously free, flat yoke surface a linear guide. The linear guide comprises a guide 06 , which in this embodiment by two parallel guide rods 07 is formed. On the guide rods 07 is a car 08 guided. The car 08 carries a coil 09 which the middle yoke 01 and the guide 06 from guide rods 07 and carriages 08 encloses.

The force on the coil 09 arises on the two sides of the coil 09 that is between the middle yoke 01 and the permanent magnet 04 are located. The leadership of the car 08 is located near the plane of the direction of movement centrally between the force-generating locations, which is why a tilting of the car or not at extremely unfavorable external loading or weight distribution on the car 08 allowed.

On the cart 08 is still an adapeter 11 arranged to receive a support carriage, not shown.

The adapter 11 continues to serve as a carrier for a Wegmesslineal 12 which preferably contains an incremental scale. The distance measuring ruler 12 Opposite is on one of the outer yokes 02 a distance measuring sensor 13 provided to the signals or marks of the moving Wegmesslineals 12 in a known manner to decode. Of course, depending on the application, an absolute or relative scale can be used. It is also conceivable, the Wegmesslineal 12 at the yoke and the distance measuring sensor 13 on the adapter 11 provide as a power supply to the coil 09 anyway on the moving car 08 must be present. The skilled person various embodiments for such sensors are known, therefore, a detailed explanation of the distance measurement is omitted at this point.

The DC linear actuator according to the invention can be kept in a stable parking position by a locking mechanism, so that when the power is turned off the car does not run unbraked on the end of the guide path. For this purpose, a switchable locking magnet 14 on the stator, ie preferably on one of the outer yokes 02 attached. This attachment takes place in the illustrated embodiment by means of an angle 15 which is on the outer yoke 02 is arranged adjustable. The locking magnet 14 switches a plunger 16 , He is in an operation transverse to the direction of movement of the coil 09 moved and with its end in a recess 17 engages on a part of the runner, preferably on the carriage 08 or on the adapter 11 is provided. By means of a position control device, which works together with the displacement measuring system, the runner can be moved to the desired parking position before the locking magnet 13 is pressed.

LIST OF REFERENCE NUMBERS

01 -

Yoke, middle

02 -

Yoke, outside

03 -

Threaded

04 -

permanent magnet

05 -

-

06 -

guide

07 -

guide rod

08 -

dare

09 -

Kitchen sink

10 -

-

11 -

adapter

12 -

Wegmesslineal

13 -

Displacement

14 -

locking magnet

15 -

corner

16 -

tappet

17 -

recess

Claims (8)

DC linear actuator comprising - a rotor with a movable coil (09); - A linear guide of a non-magnetizable material on which the rotor is guided, with a guide (06) and a movable carriage (08) for receiving the coil (09); - A stator on which a magnetic circuit is formed, with a central yoke (01) which extends through one of the coil (09) of the rotor surrounded cross-sectional area, two parallel outer yokes (02), each of which permanent magnets (04) wear which are arranged diametrically opposite to the middle yoke (01); the linear guide being mounted on the middle yoke (01) and also extending through the cross - sectional area surrounded by the coil (09), characterized in that the central yoke (01) has a rectangular cross section, and in that the linear guide abuts against the planar upper side of the middle yoke (01) is directly coupled. DC linear actuator to Claim 1 , characterized in that the linear guide comprises a mechanical rolling and / or sliding guide. DC linear actuator to Claim 1 or 2 , characterized in that the carriage (08) is mounted by a hydrodynamic or hydrostatic bearing in the linear guide. DC linear drive according to one of the Claims 1 to 3 , characterized in that it comprises a displacement measuring system. DC linear actuator to Claim 4 , characterized in that the displacement measuring system comprises a Wegmesslineal (12) which is arranged on the carriage (08). DC linear actuator to Claim 5 , characterized in that the Wegmesslineal (12) carries an incremental scale. DC linear drive according to one of the Claims 1 to 6 , characterized in that it comprises a position-locking unit for the carriage (08). DC linear actuator to Claim 7 , characterized in that the position-locking unit comprises a switchable locking magnet (14) with a plunger (16) fixed to the stator, the plunger (16) being engageable with a recess (17) on the carriage (08) to secure this in a parking position.

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