DE20012605U1 - Linear drive device - Google Patents

Description

GRÜNECKER KINKELDEY STOCKMArR 8i

LAWYER ETAT

GKS & S MAXIMILIANSTRASSE 58 D-80538 MUNICH GERMANY

German Patent and Trademark Office

Zweibrückenstr. 12
80297 Munich

LAWYERS UWYERS

MUNICH

DR. HELMUT EICHMANN

GERHARD BARTH

DR. ULRICH BLUMENROEER, LLM.

CHRISTA NIKLAS-FALTER

DR. MAXIMILIAN KINKELDEY, LLM.

SONJA SCHAEFFLER

DR. KARSTEN BRANDT

ANJA FRANKE, LL.M.

UTE STEPHANI

DR. BERND ALLEKOTTE, LLM.

PATENT ATTORNEYS PATENT ATTORNEYS

EUROPEAN PATENT ATTORNEYS EUROPEAN PATENT ATTORNEYS

MUNICH

OR. HERMANN KiNKELDEY PETER H. JAKOB WOLFHARD MEISTER HANS HILGERS DR. HENNING MEYER-PLATH ANNELIE EHNOLD THOMAS SCHUSTER DR. KWRA GOLDBACH MARTIN AUFENANGER GOTTPRIED KLITZSCH DR. HEIKE VOGELSANG-WENKE REINHARD KNAUER DIETMAR KUHL DR. FRANZ-JOSEF ZIMMER BETTINA K. REICHELT DR. ANTON K. PFAU DR. UDO WEIGELT RAINER BERTRAM JENS KOCH, M.S. (U OfPA) M.S.

8ERND ROTHAEMEL DR. DANIELA KINKELDEY DR. MARIA ROSARIO VEGA LASO

COLOGNE

DR. MARTIN DROPMANN

CHEMNITZ MANFRED SCHNEIDER

BERLIN

DIETER JANDER

OF COUNSEL PATENT ATTORNEYS

AUGUST GRÜNECKER DR. GUNTER BEZOLD DR. WALTER LANGHOFF

DR. WILFRIED STOCKMAW (■1996)

YOUR REF.

OUR SIGN / OU8 REF.

G 4325 -829/bi DATE

20.07.00

Applicant: KUNOW ELECTRONIC GMBH KAPAUNENSTRASSE14

12355 BERLIN

Linear drive device

GRÜNECKER-KINKELDEY ..

stockman a swan houses;

MAXIMILIAN STREET 58 '.

D-80538 MUNICH *"

GERMANY

«L.

+ 49- 89 4&Iacgr; 23 50· +4$ 89*2^02$?·.

http://www.grunecker.de
e-mail: postmaster@grunecker.de PfUTSCHE SANK MUNICH NJi. 17 51734 8^700 70010 SWIFT: DEUTDE MM

Linear drive device

The invention relates to a linear drive device with a shaft rotatable about its longitudinal axis, a feed element movable in the direction of the longitudinal axis and rolling elements rolling on the shaft, converting a rotary movement of the shaft into an axial movement of the feed element.

Such a linear drive device is known, for example, in the form of a ball screw spindle. The shaft, which can be rotated about its longitudinal axis, is designed as a ball screw spindle and the feed element, which can be moved in the direction of the longitudinal axis, is designed as a ball nut. The rolling elements arranged between the ball screw spindle and the ball nut are a large number of balls. These roll along guide grooves in the spindle and carry out a tangential and axial movement when the ball screw spindle rotates. This moves the ball nut in the direction of the longitudinal axis, i.e. in the axial direction.

The design of such ball screws as linear drive devices, which are already known from practice, is relatively complex, as, for example, return guides for the balls are necessary. Furthermore, the guide groove of the spindle and nut must be manufactured with great precision and at great expense and be designed to absorb the corresponding axial forces and preload forces.

The invention is based on the object of improving a linear drive device of the type mentioned at the outset in such a way that it can be manufactured simply and inexpensively and at the same time meets all the requirements placed on a linear drive device.

This object is achieved in connection with the features of the preamble of patent claim 1 in that the rolling elements are mounted on the feed element so as to be rotatable about bearing axes, which bearing axes have a particularly variable angular offset relative to the longitudinal axis of the shaft.

Due to the bearing on the feed element, the rolling elements move together with it in the direction of the longitudinal axis of the shaft without the need for guide grooves or return guides for the rolling elements. This means that the linear drive device is overall simpler in design and can be manufactured at a correspondingly low cost. The angular offset of the bearing axes relative to the longitudinal axis of the shaft, i.e. the angle of attack between the shaft longitudinal axis and the bearing axis, determines a pitch that determines the transmission ratio between the shaft and the feed element, analogous to the pitch of the guide grooves in the known ball screw spindle.

A particularly advantageous feature is a variable angular offset, which, in contrast to the known ball screws, allows the gear ratio to be changed easily.

In order to obtain rolling elements that are relatively wear-free and can absorb high radial forces, such a rolling element can be formed by a ball bearing.

In order to be able to safely support and guide the feed element with respect to the shaft, at least two rolling elements can be arranged at a distance from one another in the circumferential direction of the shaft.

In order to achieve a uniform load on all rolling elements and a uniform feed of the feed element relative to the shaft, the bearing axes can have the same angular offset to the longitudinal axis.

In order to be able to change the gear ratio as much as possible, the angular offset can be varied in size and/or direction relative to the longitudinal axis.

In order to further simplify and standardize the structure of the linear drive device according to the invention, the bearing axes can be arranged at the same distance from the longitudinal axis, so that, for example, bearing axes and rolling elements can all be constructed in the same way.

In order to establish good contact between rolling elements and shaft and in particular to ensure a play-free conversion of rotation into translation in a simple manner, at least one spring element for applying force to the bearing axis in the direction of the shaft can be arranged on the feed element or directly on the bearing axis.

In a simple embodiment, the spring element can be designed as a spring ring with an expandable diameter that is directly attached to the bearing axles.

In order to easily position the spring ring in relation to the bearing axles and to attach it to them, the spring ring can have bearing holes for the bearing axles and at least one expansion slot between them. The expansion slot forms the actual spring element, whereby this slot is expanded when the spring ring is attached to the bearing axles and accordingly, due to the elasticity of the bearing ring, presses the bearing axles and thus the rolling elements towards the shaft and into contact with the shaft.

A spring ring that is easy to produce and has sufficient spring force in the direction of the shaft can be formed, for example, by arranging a group of expansion slots between two adjacent bearing bores, some of which extend from the inner circumference and others from the outer circumference of the spring ring to the other circumference and end at a distance from this other circumference. This results in a circular ring section in the area of this group of expansion slots that runs in a meandering shape.

The feed element is essentially designed as a cage in which the rolling elements are mounted. Such a feed element can have at least two disks spaced apart from one another in the direction of the longitudinal axis, on which the bearing axes are mounted at their ends.

A simple way of storing and fastening the bearing axles can be seen in the fact that each disc has at least holes for inserting the bearing axle ends on its inner side facing the other disc. The discs can be designed the same overall, which makes the production

the linear drive device is further simplified. The discs can then be slid onto the shaft so that their corresponding inner sides face each other.

In order to easily support the bearing axes in such a way that the correspondingly variable angular offset between them and the longitudinal axis of the shaft is possible, the holes can have a substantially oval cross-section. In addition or alternatively, the holes can widen in the direction of the disk, so that this also makes it possible to pivot the bearing axes relative to the disks.

In order to allow sufficient loading of the shaft while at the same time ensuring excellent rolling behavior of the rolling elements, the shaft can be hardened and/or ground.

Another significant advantage of the linear drive device according to the invention is that a maximum propulsion force of the linear drive device can be set. The maximum propulsion force essentially results from the normal force applied by the spring rings, the number of rolling elements and the coefficient of static friction between the rolling elements and the shaft. If this maximum propulsion force is exceeded, the static friction changes to sliding friction, so that the linear drive device according to the invention simultaneously forms a slip clutch and the mechanical components are thus protected from overloading. This makes it possible, for example, for the linear drive device to drive parts against end stops without any problem.

While in the known ball screw spindles the realization of freedom from play, i.e. minimal reversal margin, is made possible by complex measures such as preloading or the like, according to the invention the rolling elements can roll directly on the shaft without play, for example by all of them resting on the shaft with sufficient pressure force.

According to the invention, it is also advantageous that the pitch can be set to very small values even with relatively large spindle diameters, so that large transmission ratios are achieved. Furthermore, only one shaft is required for linear guidance and

Propulsion is required so that no parallelism jamming occurs between two parallel shafts.

In the following, an advantageous embodiment is explained in more detail with reference to the figures attached to the drawing.

Show it:

Fig. 1 is a partially sectioned side view of the linear drive device according to the invention in a state installed in a machine shown in principle;

Fig. 2 is an enlarged view of the linear drive device according to Fig. 1;

Fig. 3 is a section along the line IH-III;

Fig. 4 is a plan view of a disk of the linear drive device, and

Fig. 5 is a view of the linear drive device corresponding to the section along the line III-III of Fig. 2 to highlight an angular offset.

Fig. 1 shows a partially sectioned side view of an embodiment of a linear drive device 1 according to the invention in the installed state. The linear drive device 1 comprises a shaft 3 with a longitudinal axis 2 and a feed element 4 arranged concentrically on the shaft 3. The shaft 3 is rotatably mounted at its ends in bearings 26 and is connected at one of its ends to a handwheel 28 via a bevel gear 27. This allows the shaft 3 to be rotated and its rotary movement is converted into a translatory movement of the feed element 4 in the direction of the longitudinal axis 2 of the shaft 3.

The feed element is designed like a cage. Inside it, a series of rolling elements are mounted on bearing axles 6. In the embodiment shown, the rolling elements 5 are designed as ball bearings 8. The feed element comprises two disks 17, 18 at its ends in the direction of the longitudinal axis 2, which serve to

Serve for supporting the ends of the bearing axes 6. The disks 17, 18 are arranged at a distance from one another in the direction of the longitudinal axis 2 and are connected to one another via a sleeve or the like. A holder 24 protrudes radially outward from the sleeve, between which and another stationary holder, for example, a test object 25 is held.

Fig. 2 shows an enlarged side view of the linear drive device 1 according to Fig. 1. The sleeve 33 is detachably attached to the outer circumference of the disks 17, 18, for example via bores 29, see Fig. 4. Inside the feed element 4, six bearing axes 6 are arranged around the shaft 3 at equal distances in the circumferential direction 9, see Fig. 3. The ends 19, 20 of the bearing axes are inserted into corresponding bores in the disks 17, 18 and are supported there. The bores 21 are arranged on the inner sides 22, 23 of the disks 17, 18 facing one another.

In the embodiment shown, five ball bearings 8 are arranged as rolling elements 5 on each of the bearing axes 6. An annular spring element 11 is arranged between adjacent ball bearings 8 along the bearing axes.

In Fig. 2 it can be seen in particular that the bearing axes 6 are arranged at an angular offset 7 relative to the longitudinal axis 2 of the shaft 3. This angular offset 7 can be varied, for example, by correspondingly rotating the disks 17, 18 relative to one another.

Fig. 3 shows a section along the line IH-III of Fig. 2.

The ball bearings 8 as rolling elements 5 are arranged concentrically around the shaft 3 and equally spaced from one another in the circumferential direction 9 of the shaft. All rolling elements 5 rest on the outer circumference of the shaft 2 and roll on it. A distance 10 from a center of the ball bearings 8 to a center of the shaft 3 is constant.

Also visible in Fig. 3 is a spring ring as a spring element 11. This has bearing holes 12 at the points corresponding to the bearing axes 6, through which the bearing axes are inserted through the corresponding spring rings. A group of expansion slots 13, 14 is arranged between each two bearing holes 12.

From these, expansion slots 13 extend from the inner circumference 15 of the spring ring 11 in the direction of the outer circumference 16 and end at a distance from this. Furthermore, the expansion slots 14 extend from the outer circumference 16 in the direction of the inner circumference 15 and end at a distance from this. Between the expansion slots 13, 14, a corresponding spring ring section is formed in a meandering shape and by placing the spring ring on the various bearing axes 6, the expansion slots 13, 14 are expanded and result in a spring force that presses the rolling elements 5 in the direction of the outer circumference of the shaft 3.

It should also be noted that the spring rings 11 are arranged along their inner circumference 15 at a distance from the shaft 3 and only the rolling elements 5 as parts of the feed element are in contact with the shaft.

Fig. 4 shows a plan view of disks 17, 18 and in particular of their inner sides 22, 23. Bores 29, 30 are formed in the circumference of disks 17, 18, which serve in particular for fastening sleeve 33, see Fig. 2, to the disks.

The discs 17, 18 have a central bore with a diameter 31 through which the shaft 3 with a smaller diameter 32, see Fig. 5, is passed.

In the embodiment shown, each of the disks 17, 18 has six holes 21 on its inner side 22, 23, into which the ends 19, 20 (see Fig. 2) of the bearing axles can be inserted. The holes have an oval cross-section, with the corresponding longer half-axis extending approximately radially outwards. The holes 21 can be designed with a widening running in the direction of the disk 17, 18 as an alternative or in addition to their oval cross-section. Both the oval cross-section and this widening are examples of the adjustable mounting of the bearing axle ends for varying the angular offset in the corresponding disks 17, 18.

In Fig. 5, a section is shown that is analogous to the section along line III-III in Fig. 2. In particular, the angular offset relative to the longitudinal axis 2 of the shaft 3, which is the same for each of the bearing axes 6, is shown here. As a result, the ball bearings 8 used as rolling elements 5 do not run perpendicular to the longitudinal axis 2 of the shaft 3 on its outer circumference.

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catch 34, but run at an angle equal to the angular offset 7 between the bearing axis and the longitudinal axis relative to this vertical plane.

A variation of the angular offset is easily possible, for example, by rotating the disks 17,18 relative to each other.

Claims (17)

1. Linear drive device ( 1 ) with a shaft ( 3 ) rotatable about its longitudinal axis ( 2 ), a feed element ( 4 ) movable in the direction of the longitudinal axis ( 2 ) and rolling elements (5) rolling on the shaft ( 3 ) and converting a rotary movement of the shaft into an axial movement of the feed element, characterized in that the rolling elements ( 5 ) are mounted on the feed element ( 4 ) rotatably about bearing axes ( 6 ) , which bearing axes have a particularly variable angular offset ( 7 ) relative to the longitudinal axis ( 2 ) of the shaft ( 3 ). 2. Linear drive device according to claim 1, characterized in that the rolling element ( 5 ) is formed by a ball bearing ( 8 ). 3. Linear drive device according to claim 1 or 2, characterized in that at least two rolling elements ( 5 ) are arranged at a distance from one another in the circumferential direction ( 9 ) of the shaft ( 3 ). 4. Linear drive device according to at least one of the preceding claims, characterized in that the bearing axes ( 6 ) have the same angular offset ( 7 ) relative to the longitudinal axis ( 2 ). 5. Linear drive device according to at least one of the preceding claims, characterized in that the angular offset ( 7 ) is variable in size and/or direction relative to the longitudinal axis ( 2 ). 6. Linear drive device according to at least one of the preceding claims, characterized in that the bearing axes ( 6 ) are arranged at the same distance ( 10 ) from the longitudinal axis ( 2 ). 7. Linear drive device according to at least one of the preceding claims, characterized in that at least one spring element ( 11 ) for applying force to the bearing axes ( 6 ) in the direction of the shaft ( 3 ) is arranged on the feed element ( 4 ). 8. Linear drive device according to at least one of the preceding claims, characterized in that the spring element ( 11 ) is designed as a spring ring which can be expanded in its circumference and which can be plugged onto the bearing axles ( 6 ). 9. Linear drive device according to at least one of the preceding claims, characterized in that the spring ring ( 11 ) has bearing bores ( 12 ) for the bearing axes ( 6 ) and at least between these at least one expansion slot ( 13 , 14 ). 10. Linear drive device according to at least one of the preceding claims, characterized in that a group of expansion slots ( 13 , 14 ) is arranged between adjacent bearing bores ( 12 ), some of which ( 13 ) extend from the inner circumference ( 15 ) and others ( 14 ) from the outer circumference ( 16 ) of the spring ring ( 11 ) to the other circumference ( 16 , 15 ) and end at a distance from these. 11. Linear drive device according to at least one of the preceding claims, characterized in that the feed element ( 4 ) has at least two disks ( 17 , 18 ) spaced apart from one another in the direction of the longitudinal axis ( 2 ), on which the bearing axes ( 6 ) are mounted at their ends ( 19 , 20 ). 12. Linear drive device according to at least one of the preceding claims, characterized in that each disc ( 17 , 18 ) has at least bores ( 21 ) for inserting the bearing axle ends ( 19 , 20 ) on its inner side ( 22 , 23 ) facing the other disc ( 18 , 17 ). 13. Linear drive device according to at least one of the preceding claims, characterized in that the bores ( 21 ) have a substantially oval cross-section. 14. Linear drive device according to at least one of the preceding claims, characterized in that the bores ( 21 ) widen in the direction of the disc ( 17 , 18 ). 15. Linear drive device according to at least one of the preceding claims, characterized in that the shaft ( 3 ) is hardened and/or ground. 16. Linear drive device according to at least one of the preceding claims, characterized in that a maximum propulsion force of the linear drive device ( 1 ) is adjustable. 17. Linear drive device according to at least one of the preceding claims, characterized in that the rolling elements ( 5 ) roll on the shaft ( 3 ) without play.