DE102013106291A1 - vibration absorber - Google Patents

Abstract

The invention relates to a vibration damper (10) for coaxial mounting in a hollow shaft, which has a damper mass (12) and an outer sleeve (14) surrounding the damper mass (12) radially outside. The absorber mass (12) and the outer sleeve (14) are connected to one another by a spring element (32). The spring element (32) is arranged in the radial direction between the absorber mass (12) and the outer sleeve (14) and is partially spaced in the radial direction from the absorber mass (12) and the outer sleeve.

Description

The invention relates to a vibration damper for coaxial mounting in a hollow shaft, which has a damping mass and the absorber mass radially outside surrounding outer sleeve, wherein the absorber mass and the outer sleeve are connected by a spring element.

Such, essentially rotationally symmetrical vibration absorber are used for the eradication of bending vibrations, for example in drive or propeller shafts, in side shafts or other rotating tubes. A main field of application is in the field of automotive engineering, where they minimize natural vibrations of waves or pipes, which are excited, for example, by a motor, by imbalances or by road bumps.

From the EP 0 988 470 B1 For this purpose, a vibration damper of the aforementioned type is known, which has a dumbbell-shaped in axial cross-section absorber mass. The damper mass has a greater extent in the axial direction than in the radial direction and is mounted on a constriction by means of an elastomeric spring. Due to this design, the elastomer spring in the radial direction is particularly stiff. In contrast, in the axial and in the tumbling direction, the elastomer spring has a lower rigidity, so that natural frequencies of the vibration absorber in these directions are below the natural frequencies in the radial direction. If a shaft in which such a vibration damper is arranged is accelerated, the natural frequencies are first excited in the tumbling direction. Due to the large axial extent a wobbling motion is also reinforced. In unfavorable cases, the absorber mass can tilt in the shaft and jam in this oblique position.

The invention is based on the object to provide a vibration damper of the type mentioned, which has an improved stability.

To solve the problem it is proposed that the spring element of the aforementioned vibration damper is arranged in the radial direction between the absorber mass and the outer sleeve and is partially spaced in the radial direction of the absorber mass and the outer sleeve.

Advantageous embodiments are the subject of the dependent claims.

The vibration absorber according to the invention has the advantage that the stiffness in the radial direction is reduced by the spacing of the spring element from the absorber mass and the outer sleeve. Relative to this, the rigidity in the axial direction is increased. This reduces a tumbling tendency of the absorber mass. A movement or rotation of the absorber mass in the tumbling direction is counteracted by the increased stiffness in the axial direction, so that the vibration absorber has self-centering properties.

In the radial direction can be arranged between the spring element and the absorber mass and / or between the spring element and the outer sleeve, an annular recess. As a result, the stiffness in the radial direction and thus also the tendency to tumble is further reduced.

The recesses may be conical in the axial direction.

The spring element may have substantially the shape of a hollow truncated cone. This causes the spring element acts in the radial direction substantially as a bending spring, which has a lower rigidity and natural frequency compared to the loaded on pressure or thrust in the axial direction elastomer spring. As a result, the tumbling tendency of the absorber mass is further reduced.

Advantageously, the spring element can be connected in an outer attachment portion with the outer sleeve and in an inner mounting portion with the absorber mass, wherein the fastening portions are arranged spaced apart in the axial direction. This allows a particularly compact arrangement of the spring element.

The attachment portions may form in another embodiment bending springs. These torsion springs, which mainly determine the spring stiffness in the radial direction, are less stiff compared to the pressure-loaded, mainly in the axial direction spring element.

The spring element advantageously has a greater extent in the axial direction than in the radial direction. As a result, a particularly compact design of the vibration damper is achieved and the ratio of stiffness in the axial and radial directions is further improved.

The spring element may have stop elements which are arranged in the radial direction between the spring element and the outer sleeve. The absorber mass can have stop elements on a radially outer outer circumferential surface. The outer sleeve may have stop elements on an inner circumferential surface. If the damper mass wobbles and is thus deflected in the radial direction, the movement of the absorber mass by the various stop elements and / or by an interaction of the various Stop elements stopped. This causes uncontrolled wobbling movements of the absorber mass to be limited.

In a further advantageous embodiment, the stop elements extend in the axial direction parallel to an axis of the vibration absorber. If the absorber mass tends to wobble and abuts the stopper members, the stopper members form a guide for an outer circumferential surface of the absorber mass. As a result, the absorber mass, if it is not already resting on the stop elements, erected again, so that its axis coincides again with the axis of the vibration absorber or the shaft in which it is installed. Also by this measure the tendency to tumble is reduced.

The center of gravity of the absorber mass is advantageously in the radial direction over a center of the spring element. If the absorber mass is deflected radially, then no moment is exerted on the absorber mass of the spring element in this arrangement. Thus, it is avoided to translate any translational movements by an indirectly generated by them moment in a rotation of the absorber mass and thus in a tumbling motion.

The outer sleeve may have an axial collar. This stabilizes the outer sleeve.

The outer sleeve and the absorber mass can each have sheaths which are integrally formed with the spring element. This results in a particularly good longevity and reliability of the vibration absorber.

The outer sleeve may have openings which allow an elastomer of the sheath and / or the spring element to be connected in a particularly effective and reliable form-fitting or material-locking manner to the outer sleeve.

Nubs may be arranged on an outer peripheral surface of the outer sleeve. These nubs, which are compressed when fitted in a hollow shaft, can compensate for a certain manufacturing tolerance, in particular at the inner diameter of the hollow shaft.

The invention will be explained in more detail with reference to an embodiment which is shown schematically in the figures. In detail show:

1 a section through an embodiment of the vibration absorber along a rotation axis;

2 an enlarged section of the view 1 where the cut is at a different angle than in 1 placed by the vibration absorber;

3 an isometric view of a first side of the vibration absorber;

4 an isometric view as in 3 from a second page and

5 a cut like in 1 , wherein the vibration damper is inserted into a hollow shaft.

1 shows a vibration damper 10 which is substantially rotationally symmetric to an axis 36 is trained. Radially inboard is a damper mass 12 arranged. The absorber mass 12 has a rotationally symmetric and with respect to a rotational movement about the axis 36 unbalance-free basic shape and is of a likewise unbalance-free outer sleeve 14 surrounded by hollow cylindrical basic shape, which is an envelope 16 made of an elastomer.

A typical mounting situation of the vibration absorber 10 in a hollow shaft 58 is in 5 shown.

On an inner peripheral surface 22 the outer sleeve 16 are, as in 1 shown in the circumferential direction evenly spaced apart stop elements 24 arranged radially inward of the inner peripheral surface 22 protrude.

The essentially straight circular absorber mass 12 has an envelope 26 on, which is formed of an elastomer. On an outer peripheral surface 28 the absorber mass 12 are stop elements 30 arranged radially outward from the outer peripheral surface 28 protrude.

The absorber mass 12 and the outer sleeve 14 are by means of a spring element 32 connected, which is formed of an elastomer.

The spring element 32 has a rotationally symmetric basic shape and has substantially the shape of a hollow truncated cone. The spring element 32 is over its entire extent in the axial direction between the absorber mass 12 and the outer sleeve 14 arranged.

On the spring element 32 Axially end is on the one hand a radially outer, in the circumferential direction on the inner peripheral surface 22 circumferential attachment section 38 formed in which the spring element 32 with the outer sleeve 14 connected is. The axially opposite end is on the spring element 32 a radially inner mounting portion 40 formed in which the spring element 32 with the absorber mass 12 connected is.

The spring element 32 is partially in the radial direction of both the absorber mass 12 as well as from the outer sleeve 14 spaced. This forms between the spring element 32 and the absorber mass 12 a recess 52 and between the outer sleeve 14 and the spring element 32 a recess 54 , The recesses 52 . 54 are annular around the axis 36 and the absorber mass 12 arranged and have a conical shape in the radial cross section.

Due to the conical shape of the spring element 32 are the outer attachment section 38 and the inner attachment portion 40 offset from each other in the axial direction. A distance between the outer attachment portion 38 and the inner attachment portion 40 in the axial direction is greater than a distance between the outer peripheral surface 28 and the inner peripheral surface 22 in the radial direction. Thus, the spring element extends 32 in cross-section with respect to the axis 36 so inclined that between the axis 36 and the spring element 32 an angle of at most 45 ° is included. Preference is given to the smallest possible angle up to a part of the outer peripheral surface 28 and / or the inner peripheral surface 22 parallel course.

Manufacturing considerations make angles between 1 ° and 10 ° appear advantageous, since such angles are easily available by means of elastomer molding in a mold and already provide a significantly increased rigidity in the axial direction.

The effect of the spring element 32 is based in particular on that by its shape in the attachment sections 38 . 40 each bending springs are formed, which act in the radial direction and are decisive for the spring properties in this direction. In a tumbling direction and in the axial direction, the spring element 32 on the other hand, they are mainly burdened by pressure or train.

An elastomer spring, which is designed as a spiral spring, usually has a lower spring stiffness and natural frequency than an elastomeric spring, which is loaded on pressure / train. In the radial direction, at the same time a direction of action of the vibration absorber 10 is, has the vibration absorber 10 thereby a lower spring stiffness and natural frequency than in the axial or tumbling direction. This will avoid the vibration damper 10 at a low frequency even tumbling.

Already by calculation can be shown that the thus configured spring element 32 has the lowest natural frequency in the direction of action. The next higher natural frequency, namely axially, is higher by about a factor of 2 than the radial natural frequency. The natural frequency in the tumbling direction is higher by a factor of 2.3 than the radial natural frequency. Thus, a negative effect on the natural frequencies is prevented and the effect in the effective direction in a desired operating range, which is limited by the natural frequency in the direction of action, not hindered.

The absorber mass 12 points around the axis 36 their highest inertia. This inertia is greater than any perpendicular to the axis 36 running wobble axis. As a result, a self-centering occurs. Similar to a gyro is inertia when rotating about the axis 36 largest, giving the spatial orientation of the absorber mass 12 stabilized and thereby a tumbling motion is prevented. In contrast, the inertia about any wobble axis is very small, so that only a small degree of imbalance occurs during a tumbling motion.

The spring element 32 has an outer peripheral surface 42 stop elements 44 on that with the stop elements 24 for limiting a deflection of the absorber mass 12 interact in the radial direction. Surfaces of the stop elements 24 . 44 which abut each other when the absorber mass 12 is deflected in the radial direction, parallel to the axis 36 , This will ensure that the absorber mass 12 set up again, so its axis again parallel to the axis of rotation of the vibration absorber 10 is aligned, if the absorber mass 12 even staggering. If the absorber mass 12 staggers and the Auslenkungsbegrenzung the stop elements 24 . 44 begins to act, then the movement of the absorber mass 12 This limits exactly where it is staggering the furthest deflected.

The outer sleeve 14 is in a cladding 16 embedded in elastomer. The outer sleeve 14 has sufficient rigidity, so that the vibration damper 10 can be fastened by press fitting in a hollow shaft. Through the pimples 20 the tolerance to variations in an inner diameter of the hollow shaft is improved.

In an alternative embodiment, the outside of the outer sleeve 14 also be left blank. This allows a press fit between the metal of the outer sleeve 14 and the metal of the hollow shaft 58 be achieved.

In the outer sleeve 14 are openings 48 provided that improved cohesion of the outer sleeve 14 and cause the surrounding elastomer. The serving 16 , the serving 26 and the spring element 32 are integrally formed of an elastomer. Depending on the application, the elastomer can by positive engagement and / or material connection with the absorber mass 12 and / or the outer sleeve 14 be connected. The openings 48 can control the flow of material through the outer sleeve 14 improve during a casting process.

The spring element 32 is designed and arranged such that a center of gravity 50 the absorber mass 12 in the radial direction with a center of the spring element 32 coincides, for example in the axial direction in the middle between the outer attachment portion 38 and the inner attachment portion 40 , Will the absorber mass 12 deflected in the radial direction, so there is no moment on the absorber mass 12 exercised because no lever arm is present. This contributes to a wobble-free operation of the vibration absorber 10 at.

The in 2 The cut shown goes out just like the cut 1 , through the axis 36 , however, is the vibration absorber 10 across from 1 a little bit around the axis 36 turned. This causes the openings 48 not to be seen in this section.

The outer sleeve 14 has an axial collar 56 on, which protrudes from the outer sleeve radially inwardly. This axial collar 56 improves the positive connection of the outer sleeve 14 with the serving 16 and stiffens the outer sleeve 14 , The outer sleeve 14 This has a rigidity, which fix the vibration damper 10 in the hollow shaft 58 sufficient.

In the 3 and 4 is the rotationally symmetric basic form of the vibration absorber 10 as well as the absorber mass 12 and the outer sleeve 14 to see. The outer sleeve 14 has an outer peripheral surface 18 burl 20 on the radially outward from the outer peripheral surface 18 protrude. The pimples 20 are circumferentially equally spaced from each other and over the entire outer peripheral surface 18 the outer sleeve 14 distributed.

The vibration absorber 10 can be obtained in particular by the absorber mass 12 and an outer sleeve 14 placed in a mold and then be encapsulated with an elastomer.

The absorber mass 12 may be formed in particular of metal. In principle, it is possible, any heavy materials for the absorber mass 12 to use. The weight of the absorber mass 12 Depending on the application, in particular between 5 and 1000 g, the absorber mass 12 in an advantageous embodiment has a weight of 250 g.

The vibration absorber 10 is particularly suitable for cardan shafts whose speed is less than 3600 revolutions / min.

Due to the particularly stiff axial component of the spring element 32 , which is subjected to axial deflection on pressure / train, a hardening of the spring element 32 in the axial direction causes when the absorber mass 12 is deflected in the axial direction.

Due to the fact that the spring element 32 has a rotationally symmetrical shape, it is evenly loaded during operation, so that no asymmetric settlement of the elastomer is to be expected, which increases the life. Both the stiffness and the imbalance of the vibration absorber 10 remain almost constant over the entire service life.

As material for the spring element 32 In particular, high-damping elastomer mixtures can be used.

The assembly of the vibration absorber 10 in a hollow shaft 58 , as in 5 shown, can happen in at least two different ways.

A first possibility of assembly is an outer peripheral surface 18 the outer sleeve 14 to wet with a mounting fluid and the vibration damper 10 in the hollow shaft 58 to press.

A second possibility is the outer peripheral surface 18 the outer sleeve 14 to be dimensioned so that the vibration damper 10 can be introduced into the pipe without relevant effort. The vibration absorber 10 is first fixed at its target position. The outer sleeve 14 Then, by means of a tool that is in the recess 54 is introduced, so widened that the outer sleeve 14 by means of adhesion to the hollow shaft 58 is squeezed.

The vibration absorber 10 has the advantage that the elastomer of the spring element 32 is loaded in the effective direction to thrust or bending, whereby a linear spring behavior and a long service life can be achieved. By the orientation of the spring element 32 in the axial direction, which is different from the outer sleeve 14 and the absorber mass 12 extends at a distance, a high axial rigidity is achieved.

The vibration absorber 10 In particular, it has a low tendency to tumble that it is its greatest moment of inertia about the axis 36 (Main axis of rotation) has. In addition, wear the compact absorber mass 12 and the high spring stiffness in tumbling direction, the In addition, the stop elements are to keep the tendency to tumble 24 . 30 . 44 designed so that the absorber mass 12 is raised when striking, if its axis of rotation staggers. Also a jamming of the absorber mass 12 in an oblique position is avoided.

Thus offers the vibration damper 10 both by avoidance as well as by limiting and damping a tumbling motion of the absorber mass 12 At operational frequencies a reliable and stable bending vibration damping with a long service life and over the lifetime largely constant properties.

LIST OF REFERENCE NUMBERS

10

vibration absorber

12

absorber mass

14

outer sleeve

16

wrapping

18

Outer circumferential surface

20

burl

22

Inner circumferential surface

24

stop element

26

wrapping

28

Outer circumferential surface

30

stop element

32

spring element

36

axis

38

outer attachment section

40

inner mounting section

42

Outer circumferential surface

44

stop element

48

opening

50

main emphasis

52

recess

54

recess

56

Axial collar

58

hollow shaft

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 0988470 B1 [0003]

Claims (15)

Vibration absorber ( 10 ) for coaxial assembly in a hollow shaft having a damping mass ( 12 ) and one the absorber mass ( 12 ) radially outwardly surrounding outer sleeve ( 14 ), wherein the absorber mass ( 12 ) and the outer sleeve ( 14 ) by a spring element ( 32 ), characterized in that the spring element ( 32 ) in the radial direction between the absorber mass ( 12 ) and the outer sleeve ( 14 ) and partially in the radial direction of the absorber mass ( 12 ) and the outer sleeve ( 14 ) is spaced. Vibration damper according to claim 1, characterized in that in the radial direction between the spring element ( 32 ) and the absorber mass ( 12 ) and / or between the spring element ( 32 ) and the outer sleeve ( 14 ) an annular recess ( 52 . 54 ) is arranged. A vibration damper according to claim 2, characterized in that the recess ( 52 . 54 ) is conical in the axial direction. Vibration damper according to one of the preceding claims, characterized in that the spring element ( 32 ) has substantially the shape of a hollow truncated cone. Vibration damper according to one of the preceding claims, characterized in that the spring element ( 32 ) in a radially outer mounting portion ( 38 ) with the outer sleeve ( 14 ) and in a radially inner mounting portion ( 40 ) with the absorber mass ( 12 ), wherein the attachment sections ( 38 . 40 ) are arranged spaced apart in the axial direction. A vibration damper according to claim 5, characterized in that the fastening sections ( 38 . 40 ) Bending springs for the absorber mass ( 12 ) form. Vibration damper according to one of the preceding claims, characterized in that the spring element ( 32 ) has a greater extent in the axial direction than in the radial direction. Vibration damper according to one of the preceding claims, characterized in that the spring element ( 32 ) Stop elements ( 44 ), which in the radial direction between the spring element ( 32 ) and the outer sleeve ( 14 ) are arranged. Vibration damper according to one of the preceding claims, characterized in that the absorber mass ( 12 ) on a radially outer peripheral surface ( 28 ) Stop elements ( 30 ) and / or that the outer sleeve ( 14 ) on an inner peripheral surface ( 22 ) Stop elements ( 24 ) having. Vibration damper according to one of claims 8 or 9, characterized in that the stop elements ( 24 . 30 . 44 ) in the axial direction parallel to an axis ( 36 ) of the vibration absorber ( 10 ). Vibration damper according to one of the preceding claims, characterized in that a center of gravity ( 50 ) of the absorber mass ( 12 ) in the radial direction over a center of the spring element ( 32 ) lies. Vibration damper according to one of the preceding claims, characterized in that the outer sleeve ( 14 ) an axial collar ( 56 ) having. Vibration damper according to claim 12, characterized in that the outer sleeve ( 14 ) an envelope ( 16 ), that the absorber mass ( 12 ) an envelope ( 26 ), and that the wrappings ( 16 . 26 ) with the spring element ( 32 ) are integral. A vibration damper according to claim 12 or 13, characterized in that the outer sleeve ( 14 ) Openings ( 48 ) having. Vibration damper according to one of the preceding claims, characterized in that an outer peripheral surface ( 18 ) of the outer sleeve ( 14 ) Pimples ( 20 ) having.

Images