EP1725373B1 - Wobble drive - Google Patents

Abstract

The invention relates to a wobble drive, in which a shaft (1) supports a wobble ring (8) by means of a pivot bearing (5), a finger (12) extending from said ring. To reduce vibrations caused by the movement of the finger (12), at least one balancing mass (20, 21) is configured on the shaft (1). Alternatively or in addition, at least one balancing mass (22, 23) can be provided on the wobble ring (8). This allows the vibrations that are caused naturally by the movement of the finger (12) to be compensated.

Description

The invention relates to a wobble mechanism according to the preambles of claims 1 and 10.

The term wobble-type gear is understood to mean a device for converting a rotational movement into an oscillating translational movement. In this case, a rotationally driven rotational element acts on a tumbling element in such a way that it is driven to reciprocate and thereby enable a further element to be translated into linear translation.

Such a wobble mechanism is z. B. from the DE 198 51 888 C1 known.

Taumelfingergetriebe be - as well as in the DE 198 51 888 C1 described - z. B. used in drills or impact hammers to convert the rotational movement of a drive in an oscillating translational motion that can be used in a striking mechanism to apply shocks on a tool.

A wobble mechanism according to the preamble of claims 1 and 10 is known from DE 3427342 A1 known.

Fig. 1 shows an example of a known wobble mechanism for such a Luftfederschlagwerk.

A shaft 1 serving as a drive shaft is driven in rotation by a drive (not shown) (eg electric motor) via a gearwheel 2. The shaft 1 is rotatably mounted on bearings 3 and 4 shown schematically. These bearings 3. 4 are usually rolling bearings, which are supported in a housing, not shown, as z. B. also in the DE 198 51 888 C1 is shown.

On the shaft 1, a pivot bearing 5 is fixed with an inner ring 5a. The inner ring 5a must be connected to the shaft 1 z. B. rotatably connected via a press fit. Optionally, the shaft 1 and the inner ring 5a can be made in one piece.

The inner ring 5 a has an annular inner running surface 6 which lies in a plane which is not perpendicular to a rotation axis 7 of the shaft 1. In the example in FIG. 1, the angle α between the plane of the inner running surface and the plane perpendicular to the rotation axis 7 is approximately 30 °.

Arranged around the inner ring 5a is a wobble ring 8, which has on its inner side an outer running surface 9 assigned to the inner running surface 6. Between the inner race 6 and the outer race 9 rolling elements 10 are arranged to be movable in a known manner. The inner ring 5a with the inner race 6, the Taumelfingerring 8 with the outer race 9 and the rolling elements 10 together operatively form the pivot bearing 5, which is designed in the example shown as a rolling bearing. Alternatively, other types of bearings such. B. plain bearings use.

On the outside of the wobble ring 8, a wobble finger 12 extends radially from an articulation point 11 to a central axis 13 of the wobble ring 8.

A Taumelfingerring 8 facing away from the end of the wobble finger 12 penetrates a piston pin 14, which in turn is attached to a drive piston 15 of a Luftfederschlagwerks.

In the drive piston 15, a percussion piston 16 belonging to the air spring impact mechanism is shown in FIG. Such air spring impact are known. However, since they do not relate to the subject matter of the invention, further explanation will be omitted.

During operation of the wobble mechanism, the shaft 1 is rotated together with the inner ring 5a. Due to the inclined inner race surface 6, the rolling elements 10 revolving therein and, with them, the wobble ring 8 are set in a tumbling motion, which can be converted into a linear reciprocating motion by the guidance of the piston pin 14 and the drive piston 15.

The wobble finger 12 is a significant imbalance mass which, with rapid movement (several hundred beats per minute), results in significant additional pendulum bearing loads acting on both the machine (bearings, housings) and the operator holding the machine.

As such wobbler gears are often used in hammers, this means that the operator is exposed not only to a shock load from the blows carried by the hammer, but also to the imbalance load from the moving wobble finger.

The invention has for its object to reduce in a wobble gear generated by the movement of the wobble finger unbalance forces and thus prevent vibration unrest of the wobble mechanism.

The object is achieved by wobble mechanism according to claims 1 and 10. Advantageous developments of the invention are defined in the dependent claims.

In a first solution according to the invention, at least one counterbalancing mass is formed on the shaft. The balancing mass is to be provided in addition to the pivot bearing held by the shaft and an imbalance caused by its asymmetrical design.

The additional, constructively provided balancing mass generates an imbalance force on the shaft which, with appropriate dimensioning and design, can be superimposed on the imbalance force generated by the movement of the wobble finger in such a way that the imbalance forces at least partially cancel out or at least diminish in the resultant ,

In a preferred embodiment of the invention, the rotary bearing has a formed on the shaft inner ring, which is associated with a Taumelfingerring. Between the inner ring and the Taumelfingerring belonging to the rotary bearing rolling elements can rotate.

The balance mass can be created by adding mass elements to the shaft. Alternatively, it is also possible to produce a corresponding balancing mass by removing material elsewhere in the shaft.

In a particularly advantageous embodiment of the invention, the shaft is mounted on two bearings, each of the bearings is assigned a balancing mass. The term "balancing mass" is to be understood abstractly. Of course, a balancing mass can also be formed by a plurality of individual mass elements, which are to be arranged according to each other for generating a common mass effect.

Thus, each balancing mass at the bearing point assigned to it is able to selectively generate a counteracting the effect of the wobble finger counterforce, in order to reduce the resulting bearing force in this way.

In a particularly advantageous embodiment of the invention, the axial distance between a bearing and the respectively associated therewith balancing mass is minimal. In this way, the effect of the balancing mass can be transferred particularly well to its associated bearing point.

In a further advantageous embodiment, the balancing masses associated with the two bearing points are arranged opposite one another with respect to the axis of rotation of the shaft. This means that the centrifugal forces generated by the balancing masses are offset by 180 ° to each other. In addition, the two balancing masses generate a torque about the center of the shaft, which counteracts the wobble generated by the wobble finger.

It is particularly advantageous if the wobble ring is essentially rotationally symmetrical, with the exception of the region from which the wobble finger extends radially. The Taumelfingerring should have the lowest possible weight to avoid the emergence of additional tumbling moments.

In another, as defined in claim 10 solution of the invention underlying object is provided on the wobble ring at least one balancing mass in a range that neither at the articulation point, still, based on the center axis of the wobble ring, opposite of the articulation point at the the wobble finger extends radially from the wobble ring is located.

It has surprisingly been found that the application of balancing masses, which are related to the Taumelfingerring laterally to the wobble finger, generates an imbalance force which counteracts the tumbling moment of the wobble finger and thus leads to a reduction of the vibration forces.

Also in this variant, the arranged between the shaft and the Taumelfingerring, obliquely rotating bearings can be realized by different types of bearings, the rolling bearing is preferable due to the lower friction and high wear resistance.

It is particularly advantageous if two balancing masses are provided which are arranged opposite one another on the wobble ring, relative to the central axis of the wobble ring. Here are the balancing masses with the same angular distance, preferably with 90 ° relative to the center axis of the wobble ring, relative to the pivot point of the wobble finger.

It is furthermore advantageous if the wobble ring, with the exception of the point of articulation, from which the wobble finger extends, and the areas in which the additional balance masses are provided, is substantially rotationally symmetrical. It has been found that the arrangement of balancing masses in areas other than those defined above does not lead to an improvement in the vibration situation, but rather to an increase in the imbalance forces and thus the vibrations.

In a particularly advantageous embodiment of the invention, the two solutions of the problem described above separately from each other are combined. This means that the wobble gear on the one hand has a shaft to which additional balancing masses are attached, and on the other hand also on the wobble ring balancing masses are provided in the manner described above. The combination of balancing masses and the resulting total forces and moments cause a significant reduction in unwanted vibrations.

Fig. 1

einen schematischen Schnitt durch ein aus dem Stand der Technik bekanntes Taumelfingergetriebe für ein Luftfederschlagwerk;

Fig. 2

ein Diagramm mit den zu erwartenden Lagerkräften bei einem nicht erfindungsgemäß ausgestalteten Taumelfingergetriebe;

Fig. 3

schematisch ein Taumelfingergetriebe gemäß der Erfindung;

Fig. 4

ein Diagramm zur Erläuterung der Reduzierung der Gesamtlagerlasten durch Auswuchtmassen auf der Welle (erste Ausführungsform der Erfindung);

Fig. 5

ein Diagramm zur Erläuterung der Lagerlasten bei Unwuchten auf der Welle und auf dem Taumelfingerring (dritte Ausführungsform der Erfindung).

These and other advantages and features of the invention are explained below with the aid of the accompanying figures. Show it:

Fig. 1

a schematic section through a known from the prior art wobble gear for an air spring impact mechanism;

Fig. 2

a diagram with the expected bearing forces in a non-inventively designed wobble action gearbox;

Fig. 3

schematically a wobble mechanism according to the invention;

Fig. 4

a diagram for explaining the reduction of the total bearing loads by balancing masses on the shaft (first embodiment of the invention);

Fig. 5

a diagram illustrating the bearing loads at imbalances on the shaft and on the wobble ring (third embodiment of the invention).

The basic structure of a wobble-type transmission is known and has already been explained above with reference to FIG. To avoid repetition, reference is made to the description there.

In the known wobble mechanism of Fig. 1 occur at the bearings 3, 4 bearing loads, which are plotted in Fig. 2 by way of example over time. The curve a represents the bearing forces in the direction of a transverse axis (horizontal plane), while the curve b corresponds to the bearing load in the direction of the machine vertical axis. It is assumed that the wobble finger 12 is directed substantially vertically, ie in the direction of the machine vertical axis.

When superimposing the curves a and b, the total bearing load results according to curve c.

The wobble-type transmission according to the invention will be explained with reference to the schematic representation of FIG.

Fig. 3 accesses from Fig. 1, the essential components, namely the shaft 1, the Taumelfingerring 8 and the wobble finger 12. Furthermore, the bearings 3 and 4 are shown symbolically. Incidentally, the detailed technical embodiment can essentially be carried out according to FIG. 1.

In a first embodiment of the invention balancing masses 20 and 21 are provided on the shaft 1, wherein the balancing mass 20 as close as possible (relative to the axial distance a) to the bearing point 3 and the balancing mass 21 are arranged as close as possible to the bearing point 4. Furthermore, it can be seen in FIG. 3 that the balancing masses 20 and 21 are arranged opposite one another with respect to the axis of rotation 7 of the shaft. As a result, the balancing masses 20 and 21 generate a torque about the axis X, which is opposite to the tumbling moment of the wobble finger 12.

The dimensioning of the balancing masses 20, 21, in particular their mass and their distance from the axis of rotation 7, the expert can easily determine by experiment.

The distance a of the balancing mass 20 to the bearing 3 and according to the distance from the balancing mass 21 to the bearing 4 should be as low as possible in order to develop a maximum effect of the balancing masses 20, 21. This results from the fact that the closer the balancing weights 20, 21 are to the bearing points 3, 4, the greater the momentum around the X axis.

The balancing masses 20, 21 may, as shown in Fig. 3, be formed by attaching additional mass elements. Alternatively, it is also possible to remove material from the shaft 1 in each case on the opposite shaft side in order to produce the desired force. As a force, the product of a balancing mass is generally referred to with the distance of its center of gravity from the axis of rotation 7.

With a suitable dimensioning and arrangement of the balancing masses 20, 21, the total bearing load c shown in FIG. 2 can be reduced. In Fig. 4, the curve c of Fig. 2 is taken. The curve d corresponds to the course of the total bearing load when the balancing masses 20, 21 are provided on the shaft 1. The resulting significant reduction of the total storage loads can be seen directly in Fig. 4.

In a second embodiment of the invention, additional balance masses 22 and 23 are attached to the wobble ring 8 (Figure 3). In the second embodiment of the invention, however - in contrast to the representation in FIG. 3 - no balancing masses 20, 21 are formed on the shaft 1.

The balancing masses 22, 23 are arranged opposite each other in a region which is offset in each case by 90 ° relative to the articulation point 11 of the wobble finger 12.

The balancing masses 22, 23 lead to an alignment of the maximum bearing forces in the high (Y) and transverse (X) directions of the machine, whereby the effective bearing forces can be made uniform. As was shown in FIG. 2, the bearing forces acting in the machine vertical axis (curve b) are greater than the forces in the transverse machine axis (curve a).

By applying the balancing masses 22, 23 a reduction of the undesired vibration forces is thus already achieved.

In a third embodiment of the invention shown in Fig. 3, the teachings of the first and second embodiments described above are combined. This means that the first by the balancing masses 22, 23 on the wobble ring 8, the maximum bearing forces acting in the X and Y directions are equalized. These forces are then largely compensated by the balancing masses 20, 21 on the shaft 1. Finally, a bearing force curve as shown as curve e in FIG. 5 is expected.

If one compares the curve e of FIG. 5 with the curve c of FIG. 2, it can be clearly seen that the high vibrational forces existing without the additional balancing masses 20, 21, 22, 23 can be largely eliminated.

The first and second embodiments in themselves already bring a significant improvement to the reduction of unwanted vibration forces. The combination of the first and second embodiments to the third embodiment allows even further vibration reduction.

Claims (18)

1. Wobble drive, having

   - a shaft (1);

   - a pivot bearing (5) which is disposed on the shaft (1) and is inclined with respect to an axis of rotation (7) of the shaft (1);

   - a wobble finger (12) which extends away from the axis of rotation (7) of the shaft (1) and is held by the pivot bearing (5);

   characterised in that at least one balancing mass (20, 21) is formed on the shaft (1).
2. Wobble drive as claimed in claim 1, characterised in that the balancing mass (20, 21) is disposed on the shaft (1) in such a manner that it counteracts the design-generated unbalance of the wobble drive.
3. Wobble drive as claimed in claim 1 or 2, characterised in that

   - the pivot bearing (5) comprises an inner ring (5a) formed on the shaft (1), having an annular inner running surface (6) for rolling bodies (10), wherein the inner running surface (6) lies in a plane which is not perpendicular to the axis of rotation (7) of the shaft (1);

   - the pivot bearing (5) is allocated a wobble ring (8) which is disposed around the inner ring (5a), having an annular outer running surface (9) for the rolling bodies (10) which is allocated to the inner running surface (6); and that

   - the wobble finger (12) extends from the wobble ring (8) in a radial manner with respect to a central axis (13) of the wobble ring (8).
4. Wobble drive as claimed in any one of claims 1 to 3, characterised in that the balancing mass (20, 21) can be produced by removing material of the shaft (1).
5. Wobble drive as claimed in any one of claims 1 to 4, characterised in that

   - the shaft (1) is mounted on at least two bearing points (3, 4);

   - at least one of the bearing points (3, 4) is allocated a balancing mass (20, 21).
6. Wobble drive as claimed in claim 5, characterised in that

   - the shaft (1) is mounted on two bearing points (3, 4), and that

   - the bearing points (3, 4) are each allocated a balancing mass (20, 21).
7. Wobble drive as claimed in claim 6, characterised in that the axial spacing (a) between a bearing point (3) and the balancing mass (20) allocated thereto is minimal.
8. Wobble drive as claimed in claim 6 or 7, characterised in that the balancing masses (20, 21) which are allocated to the two bearing points (3, 4) are disposed lying opposite in relation to the axis of rotation (7) of the shaft (1).
9. Wobble drive as claimed in any one of claims 1 to 8, characterised in that with the exception of the region from which the wobble finger (12) extends, the wobble ring (8) is substantially rotationally symmetrical .
10. Wobble drive, having

    - a shaft (1);

    - a pivot bearing (5) which is disposed on the shaft (1) and is inclined with respect to an axis of rotation (7) of the shaft (1);

    - a wobble ring (8) which is held by the pivot bearing (5);

    - a wobble finger (12) which extends at an articulation point (11) from the wobble ring (8) in a radial manner with respect to a central axis (13) of the wobble ring (8);

    characterised in that the wobble ring (8) is provided with at least one balancing mass (22, 23) in a region which is not located either at the articulation point (11) or opposite the articulation point (11) in relation to the central axis (13) of the wobble ring (8).
11. Wobble drive as claimed in claim 10, characterised in that

    - the pivot bearing (5) comprises an inner ring (5a) which is formed on the shaft (1), having an annular inner running surface (6) for rolling bodies (10), wherein the inner running surface (6) lies in a plane which is not perpendicular to the axis of rotation (7) of the shaft (1); and that

    - the wobble ring (8) is allocated to the inner ring (5a) and comprises an annular outer running surface (9) for the rolling bodies (10) which is allocated to the inner running surface (6).
12. Wobble drive as claimed in claim 10 or 11, characterised in that two balancing masses (22, 23) are provided which are disposed on the wobble ring (8) so as to lie opposite one another in relation to the central axis (13) of the wobble ring (8).
13. Wobble drive as claimed in any one of claims 10 to 12, characterised in that two balancing masses (22, 23) are provided and that in relation to the central axis (13) of the wobble ring (8) the articulation point (11) is positioned at the same angular spacing with respect to the two balancing masses (22, 23).
14. Wobble drive as claimed in any one of claims 10 to 13, characterised in that

    - one balancing mass (22) is disposed in a region of the wobble ring (8) which is offset relative to the articulation point (11) of the wobble finger (12) by +90° in relation to the central axis (13) of the wobble ring (8), and that

    - the other balancing mass (23) is disposed in a region of the wobble ring (8) which is offset relative to the articulation point (11) of the wobble finger (8) by -90° in relation to the central axis (13) of the wobble ring (8).
15. Wobble drive as claimed in any one of claims 10 to 14, characterised in that the wobble ring (8) is substantially rotationally symmetrical with the exception of the articulation point (11), from which the wobble finger (12) extends, and of the regions, in which the balancing masses (22, 23) are provided.
16. Wobble drive as claimed in any one of claims 10 to 15, characterised in that the balancing mass (22, 23) can be produced by removing material of the wobble ring (8).
17. Wobble drive as claimed in at least one of claims 1 to 9 and at least one of claims 10 to 16.
18. Wobble drive as claimed in any one of claims 1 to 17, characterised in that a balancing mass (20, 21, 22, 23) is formed from several balancing mass elements.

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