Vibration absorber consisting of spoke spring buffer

Abstract

The proposed structure of a vibration damper (13, 18, 25) with at least two dampers (6, 12, 19, 20, 21) can effectively damp the frequency characteristics of a crankshaft. The at least two dampers each include at least one spoke spring (29, 30, 31). The dampers (6, 12, 19, 20, 21) preferably have different natural frequencies, which are matched to the frequency characteristics of the crankshaft. The dampers (6, 12, 19, 20, 21) have a frequency characteristic that is independent or only slightly independent of the aging of the spoke springs (29, 30, 31) and of the ambient temperature. The corresponding vibration damper (13, 18, 25) can be easily constructed and installed.

Description

Technical Field

[0001] The invention relates to a vibration damper for use in a motor vehicle, in particular for damping vibrations of a crankshaft. Background Art

[0002] In recent years, crankshaft dampers for reducing crankshaft vibrations have become known. During operation, the crankshaft on an internal combustion engine rotates in response to the periodic pulses of the cylinders during the alternating operation of the cylinders. This generates vibrations in the crankshaft, which are detrimental to the long-term service life of the engine and its associated components. Known crankshaft dampers can be provided with an elastomer ring pressed between the flange and the flywheel mass. There are many embodiments for this. Typical examples are presented in EP 1 412 656 B1 or DE 60119 333 T2. In this solution, since the spring characteristics of the elastomer are temperature-dependent, a relatively large mass is used, thereby ensuring a minimum effect even under unfavorable temperature conditions. Another known solution for reducing crankshaft vibrations is to use a viscous damper. Typical examples are presented in EP 197 08082A1 or US 8,863,925B2. Compared with crankshaft dampers with elastomer rings, viscous dampers achieve better damping effects. However, there is a significantly higher price in comparison. Crankshaft vibration dampers with compression springs are also known. Examples of this are known from DE 199 49 206 B4 or DE 196 52 730 B4. DE 10 2015 213 653 A1 discloses a vibration damper based on a spoke spring, which acts as a buffer and thus precisely reduces the frequency of the crankshaft. This vibration damping performance is usually not sufficient. Summary of the invention

[0003] On this basis, the object of the present invention is to at least partially overcome the problems known in the prior art. A vibration damper rotatable about a rotation axis, particularly for use in a drive train of a motor vehicle for reducing torsional vibrations, comprises at least two dampers, wherein each damper has a natural frequency, wherein each damper has at least one spoke spring, the at least one spoke spring having a natural frequency of the damper, wherein each spoke spring has a circular ring-shaped outer element on the radial outside and a connecting element on the radial inside for connection to a shaft and has a plurality of spokes extending in the radial direction, the spokes being elastic, wherein the vibration damper comprises at least two dampers, the at least two dampers each having a different natural frequency.

[0004] The vibration damper is preferably formed only of buffers, each of which has a natural frequency, and each of which comprises at least one spoke spring with a corresponding natural frequency. Each buffer can be formed by one or more spoke springs with the same natural frequency. The spoke spring with a spring coupling as a vibration damper is basically formed by a rotating mass with a defined moment of inertia of an external element, which is connected to a connecting element via spokes designed as spring elements and is connected to a shaft, in particular a crankshaft, via the connecting element. The natural frequency of the vibration damper is generated by the torsional rigidity of the spring element and the moment of inertia of the rotating mass. The spokes are preferably arranged in one plane, whereby the axial installation space requirement of the spoke spring can be reduced to a minimum.

[0005] It has been shown that the use of at least two dampers consisting of spoke springs with different natural frequencies makes it possible in particular to damp crankshaft vibrations. In this case, the natural frequency can be adapted to the overall system consisting of the shaft to be damped with the shaft natural frequency and the vibration absorber having at least two dampers. The spoke springs are made of steel, at least the spokes are preferably made of spring steel.

[0006] A vibration damper consisting of a damper each comprising at least one spoke spring allows effective damping of the frequency response of a crankshaft, in particular. The individual dampers are formed by spoke springs made of steel, whereby the influence of aging and temperature is significantly reduced compared to the prior art crankshaft vibration dampers with elastomer elements. The corresponding vibration damper is also of simple construction and can be manufactured cost-effectively.

[0007] A preferred design is that the first natural frequency of the first damper is coordinated with the natural frequency of the shaft, in particular corresponds to the natural frequency of the shaft or differs therefrom by up to 20 Hz. This results in a frequency characteristic (i.e., amplitude relative to rotational frequency) having two maxima, wherein one maximum occurs at a higher frequency than the natural frequency of the shaft and the other maximum occurs at a lower frequency than the natural frequency of the shaft. The amplitude of the maximum is smaller than the amplitude at the natural frequency of the undamped shaft. It is also preferred that the second natural frequency of the second damper is coordinated with the frequency of one of these maxima or differs therefrom by up to 20 Hz. This results in a frequency characteristic having three maxima, but all three maxima have smaller amplitudes than the previous maximum in the case of one damper. According to the same concept, additional dampers can be added, wherein the damping is further improved.

[0008] Preferably, the vibration absorber comprises at least three buffers, and the at least three buffers respectively have different natural frequencies. The vibration damping can be further improved by increasing the number of buffers.

[0009] Preferably, the damper comprises a plurality of spoke springs, each of which has a natural frequency of the damper. This simplifies the construction of the damper, since, in particular when the spoke springs are produced by a stamping process, it is easier to construct a plurality of thin spoke springs, which have a smaller expansion in the axial direction, than thicker spoke springs.

[0010] Preferably, the spokes are designed as torsion spring rods. The spokes can advantageously accommodate relative movements between the outer element and the connecting element and can be designed in a simple manner.

[0011] Preferably, the natural frequencies of all dampers are different from one another. As a result, the natural frequencies of the dampers can cover a larger frequency range. Preferably, the natural frequencies of the dampers are selected in such a way that the natural frequencies of the shaft are in the region covered by the natural frequencies of the dampers. Preferably, the natural frequencies of the dampers are selected in such a way that the natural frequencies of the crankshaft are in the middle 20% of the frequency space spread out by the natural frequencies of the dampers. For example, if the minimum natural frequency of a damper is 400 Hz and the maximum natural frequency is 620 Hz, the natural frequency of the crankshaft is preferably in the range of 488 Hz to 532 Hz.

[0012] Preferably, the spoke springs are arranged successively in the direction of the rotation axis, wherein the spoke springs adjacent to each other in the direction of the rotation axis are in contact with each other. The spoke springs of different dampers can rotate relative to each other at least up to a predeterminable critical amplitude. Due to the friction between the adjacent spoke springs caused by the contact in the direction of the rotation axis, the damping of the relative movement is achieved without the need to construct an additional friction element.

[0013] A vibration damper for damping the vibration characteristics of a specific crankshaft system having a crankshaft natural frequency is also proposed, wherein the vibration damper is designed as described herein, wherein a first damper has a first natural frequency and a second damper has a second natural frequency, and wherein the first natural frequency is lower than the crankshaft natural frequency and the second natural frequency is higher than the crankshaft natural frequency, thereby achieving vibration damping of the crankshaft.

[0014] A vibration damper for reducing the vibration characteristics of a specific crankshaft system having a crankshaft natural frequency is also proposed, wherein the vibration damper is constructed as implemented herein, wherein a first damper has a first natural frequency, which differs from the crankshaft natural frequency by a maximum of 20 Hz, wherein a second damper has a second natural frequency, which differs from a maximum frequency of the frequency characteristics of the crankshaft system damped by the first damper by a maximum of 20 Hz.

[0015] In this case, the first damper is matched with its first natural frequency to the natural frequency of the crankshaft. As a result, instead of the maximum value of the natural frequency of the crankshaft without vibration damping, a frequency characteristic with two maxima is produced, which have smaller amplitudes on the right and left (i.e. at higher and lower frequencies) than the maximum value without vibration damping. The second natural frequency of the second damper is then matched to one of the frequencies of one of the maxima. The resulting frequency characteristic thus has three maxima with reduced amplitudes.

[0016] It can be advantageously improved that at least one further damper is designed with a further natural frequency, wherein for each further damper it is applicable that its further natural frequency differs by a maximum of 20 Hz from the frequency of the maximum value of the frequency characteristic of the crankshaft system damped by the remaining dampers. As an example, a third damper is designed with a third natural frequency that is coordinated with the frequency of one of the three maximum values ​​in a system with two dampers, and so on.

[0017] A component is also proposed, comprising a crankshaft having a crankshaft natural frequency and a vibration damper as described herein, wherein a first damper has a first natural frequency, which is lower than the crankshaft natural frequency, and a second damper has a second natural frequency, which is higher than the crankshaft natural frequency. This allows a vibration damping of the frequency characteristic to be achieved.

[0018] It should be noted in advance that the ordinal numbers used here ("first", "second", ...) are primarily (only) used to distinguish between a plurality of objects, variables or processes of the same type, i.e., in particular, no mandatory presupposition is given to the correlation and / or order of these objects, variables or processes with respect to one another. If a correlation and / or order is required, this is explicitly stated here or is obvious to a person skilled in the art when studying the specifically described embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention and the technical field are described in more detail below with reference to the accompanying drawings. It should be noted that the present invention should not be limited by the illustrated embodiments. In particular, if there is no clear indication to the contrary, partial solutions of the facts described in the drawings can also be extracted and combined with other components and cognitions in this specification and / or the drawings. It should be pointed out in particular that the drawings and the dimensional ratios shown in particular are only schematic. The same reference numerals represent the same objects, so that the descriptions in other drawings can be supplemented as necessary. The drawings show:

[0020] Figure 1 A first vibration model not belonging to the present invention is shown;

[0021] Figure 2 shows the frequency characteristics of the first vibration model;

[0022] Figure 3 A vibration model of a first example of a shock absorber consisting of two buffers is shown;

[0023] Figure 4 shows the frequency characteristics of a first example of a vibration absorber;

[0024] Figure 5 A vibration model of a second example of a shock absorber consisting of five buffers is shown;

[0025] Figure 6 shows the frequency characteristics of a second example of a vibration absorber;

[0026] Figure 7 and Figure 8 A perspective view and a cross section of a third example of a vibration absorber are shown. DETAILED DESCRIPTION

[0027] Figure 1 A first vibration model of an example not covered by the present invention is shown. The first vibration model comprises a crankshaft system 1, which represents the crankshaft of an internal combustion engine and the oscillating mass associated therewith. The internal combustion engine (not shown) generates a torque 2, which is fed into the crankshaft system 1. This torque is frequency-dependent in a known manner and the frequency characteristic of the crankshaft system 1 is likewise dependent on a natural frequency or a resonant frequency. Figure 2 The frequency response of the crankshaft system 1 is shown as crankshaft frequency response 3 , which is expressed as an amplitude A of the crankshaft over a rotational frequency f. The crankshaft system 1 has a single crankshaft natural frequency 4 , at which a single maximum 5 of the crankshaft frequency response 3 is located.

[0028] Figure 1 Also shown is a first buffer 6 which is configured as a spoke spring buffer having a spoke spring. Figure 7 and Figure 8 The spoke spring damper is described in detail. The spoke damper has an external annular outer element and an internal connecting element, the connecting element is used to connect to the crankshaft, and the outer element and the connecting element are connected to each other via radially extending elastically deformable spokes. The natural frequency of the first damper 6 can be determined by designing the spoke spring damper, in particular by determining the mass of the outer element, the radius of the outer element and / or the number of spokes and / or the spring constant (thickness). Here, the first damper 6 forms a vibration system 7, and the vibration characteristics of the vibration system are determined by the first damper 6. The natural frequency of the first damper 6 is coordinated with the crankshaft natural frequency 4.

[0029] If the vibration system 7 is now connected to the crankshaft system 1, wherein the connecting element (not shown) of the first damper 6 is connected to the crankshaft in a rotationally fixed manner, the vibration system and the crankshaft system together form a Figure 2 8 of the first crankshaft system frequency characteristic shown in FIG. The frequency characteristic of the first crankshaft system 8 having a damped vibration has a first maximum value 10 and a second maximum value 11, the frequencies of which are below the crankshaft natural frequency 4 for the first maximum value 10 and above the crankshaft natural frequency 4 for the second maximum value 11. The amplitude A of the first maximum value 10 and the second maximum value 11 are significantly lower than the amplitude A of the maximum value 5 of the crankshaft frequency characteristic 3. Figure 2 The crankshaft frequency characteristic 3 shown in FIG. 1 is the frequency characteristic of a pure crankshaft system 1 without a damper.

[0030] In the following Figures 3 to 6 Two examples of vibration dampers according to the invention are explained in FIG. Figure 3 and Figure 5 As shown in the figure, the frequency characteristics belonging to it are Figure 4 and Figure 6 In Figure 4 and Figure 6 For comparison, the following are shown: Figure 2 9. Frequency characteristics of the first crankshaft system.

[0031] Figure 3 The vibration model of the first example of the first shock absorber 13 composed of the first shock absorber 6 and the second shock absorber 12 is shown. The first shock absorber 6 corresponds to Figure 1 The first buffer 6 in the embodiment. The second buffer 12 is also designed as a spoke spring buffer. Here, the natural frequency of the second buffer is tuned to Figure 2 10, i.e., the frequency which is tuned to the higher maximum value of the first crankshaft frequency characteristic 9. The first vibration damper 13 is connected to a crankshaft (not shown) by connecting the first and second dampers 6, 12, via connecting elements (not shown), so that the vibration damper 13 is connected to the crankshaft system 1, and the vibration damper and the crankshaft system together form a second crankshaft system 14 which is damped.

[0032] The second crankshaft system 14 after vibration reduction shows a second crankshaft system frequency characteristic 15, such as Figure 4As shown. The crankshaft system frequency characteristic has, in addition to the second maximum value 11 corresponding to the second maximum value of the first crankshaft system frequency characteristic 9, a third maximum value 16 and a fourth maximum value 17, wherein the third maximum value 16 is at a frequency f lower than the frequency f of the first maximum value 10 and the fourth maximum value 17 is at a frequency f higher than the frequency of the first maximum value 10. Here, the amplitude A of the third maximum value 16 and the fourth maximum value 17 is smaller than the amplitude A of the first maximum value 10 of the first crankshaft system frequency characteristic 9. It is shown here that the use of a vibration damper 13 having a plurality of dampers 6, 12 designed as spoke spring dampers allows good vibration damping of the crankshaft system 1.

[0033] Figure 5 The vibration model of the second example of the second vibration absorber 18 is shown, and the second vibration absorber includes a first buffer 6 and a second buffer 12, and the first buffer and the second buffer are designed as described above. The second vibration absorber 18 also includes a third buffer 19, a fourth buffer 20 and a fifth buffer 21, and the third buffer, the fourth buffer and the fifth buffer are respectively configured as spoke spring buffers. Figure 5 The natural frequency of the undamped crankshaft system 1 (here 525 Hz) and the natural frequencies of the first shock absorber 6 (400 Hz), the second shock absorber 12 (450 Hz), the third shock absorber 19 (500 Hz), the fourth shock absorber 20 (560 Hz) and the fifth shock absorber 21 (620 Hz) are respectively given in . If the second shock absorber 18 is connected to the crankshaft system 1, a damped crankshaft system 22 is formed. Figure 6 , in addition to the curve of the first crankshaft system frequency characteristic 9 used as a reference curve, a corresponding third crankshaft system frequency characteristic 23 is shown. The third crankshaft system frequency characteristic 23 accordingly has a sixth maximum value 24, which extends over a frequency below the lowest natural frequency of the dampers 6, 12, 19, 20, 21 (here 400 Hz) to above the highest natural frequency of the dampers 6, 12, 19, 20, 21 (here 620 Hz). The amplitude A of the maximum value 24 is significantly lower than the amplitudes of the first maximum value 10 and the second maximum value 11, so that the crankshaft vibrations are significantly reduced here.

[0034] Figure 7 and Figure 8 A perspective view showing an example of the third vibration absorber 25 ( Figure 7 ) and Section View ( Figure 8). Unless otherwise expressly stated, the two figures are described together below, so these embodiments refer to both figures. In this example, the third shock absorber 25 is composed of three buffers: a first buffer 6, a second buffer 12 and a third buffer 19. Each buffer 6, 12, 19 is respectively composed of three identical spoke springs, the first buffer 6 is composed of three identical first spoke springs 29, the second buffer 12 is composed of three identical second spoke springs 30, and the third buffer 19 is composed of three identical third spoke springs 31, in particular Figure 8 shown.

[0035] The spoke spring damper is composed of an annular outer element 26, an inner connecting element 27 and radially extending spokes 28 between them, which are only partially provided with reference numerals for the sake of clarity. The spokes 28 are designed as torsion spring rods. In the direction of the rotation axis 32 of the damper 6, 12, 19, adjacent spoke springs 29, 30, 31 are in contact with each other, so that in the case of a deflection of the damper 6, 12, 19, the movement caused by the existing friction is damped.

[0036] The natural frequency of the dampers 6, 12, 19 and of the spoke spring dampers in general can be achieved here by changing the corresponding outer element 26, in particular by changing the mass and / or radius of the outer element 26 and / or by changing the spokes 28, in particular by changing the number of spokes 28 and / or the spring constant of the spokes 28. In this example, the outer elements 26 of the first damper 6, the second damper 12 and the third damper 19 are different, which have different extensions and different masses in the radial direction relative to the rotation axis 32, thereby causing different moments of inertia of the outer elements 26 of the different spoke springs 29, 30, 31. In this example, the number, position and design of the spokes 28 of the spoke springs 29, 30, 31 of the dampers 6, 12, 19 are identical. The dampers 6, 12, 19 are connected to a crankshaft (not shown) via a connecting element 27.

[0037] The dampers 6, 12, 19 in the third damper 25 are connected via rolling bodies 33, which allow relative movement relative to each other. For this purpose, corresponding elongated holes are formed in the outer element 26, which allow relative movement of the dampers 6, 12, 19 relative to each other.

[0038] The proposed design of the vibration damper 13, 18, 25 with at least two dampers 6, 12, 19, 20, 21, each of which comprises at least one spoke spring, enables effective damping of the frequency characteristics of the crankshaft. The dampers 6, 12, 19, 20, 21 have preferably different natural frequencies, which are matched to the frequency characteristics of the crankshaft. The dampers 6, 12, 19, 20, 21 have a frequency characteristic that is independent or only slightly independent of the aging of the spoke springs 29, 30, 31 and of the ambient temperature. The corresponding vibration damper 13, 18, 25 can be designed and installed in a simple manner.

[0039] Reference numerals list

[0040] 1 Crankshaft system

[0041] 2 Torque

[0042] 3 Crankshaft frequency characteristics

[0043] 4 Crankshaft natural frequency

[0044] 5 Maximum

[0045] 6 First buffer

[0046] 7 Vibration system

[0047] 8 Damped first crankshaft system

[0048] 9 Frequency characteristics of the first crankshaft system

[0049] 10 First maximum value

[0050] 11 Second maximum

[0051] 12 Second buffer

[0052] 13 First shock absorber

[0053] 14 Damped second crankshaft system

[0054] 15 Second crankshaft system frequency characteristics

[0055] 16 Third maximum

[0056] 17 Fourth Maximum

[0057] 18 Second shock absorber

[0058] 19 Third buffer

[0059] 20 Fourth buffer

[0060] 21 Fifth Buffer

[0061] 22 Damped third crankshaft system

[0062] 23 Frequency characteristics of the third crankshaft system

[0063] 24 Maximum

[0064] 25 Third shock absorber

[0065] 26 External components

[0066] 27 Connecting elements

[0067] 28 spokes

[0068] 29 First spoke spring

[0069] 30 Second spoke spring

[0070] 31 Third spoke spring

[0071] 32 Rotation axis

[0072] 33 Rolling element

[0073] A amplitude

[0074] f Rotation frequency

Claims

1. A vibration damper (13, 18, 25) for reducing torsional vibrations, characterized in that The vibration absorber is rotatable about a rotation axis (32), and comprises at least two buffers (6, 12, 19, 20, 21), wherein each buffer (6, 12, 19, 20, 21) has a natural frequency, wherein each buffer (6, 12, 19, 20, 21) has at least one spoke spring (29, 30, 31), and the at least one spoke spring has the natural frequency of the buffer (6, 12, 19, 20, 21), wherein each spoke spring has a circular ring-shaped outer element on the radial outside and a connecting element for connecting to a shaft on the radial inside, and has a plurality of spokes extending in the radial direction, wherein the spokes are elastically configured, wherein the at least two buffers have different natural frequencies respectively, and the spoke springs (29, 30, 31) are arranged successively in the direction of the rotation axis, wherein the spoke springs adjacent to each other in the direction of the rotation axis are in contact with each other.

2. The vibration absorber (13, 18, 25) according to claim 1, characterized in that in, The vibration absorber comprises at least three buffers (6, 12, 19, 20, 21), and the at least three buffers respectively have different natural frequencies.

3. The vibration absorber (13, 18, 25) according to claim 1, characterized in that in, The buffer (6, 12, 19, 20, 21) comprises a plurality of spoke springs (29, 30, 31), wherein the plurality of spoke springs respectively have the natural frequency of the buffer (6, 12, 19, 20, 21).

4. The vibration absorber (13, 18, 25) according to claim 1, characterized in that in, The natural frequencies of all the buffers (6, 12, 19, 20, 21) are different from each other.

5. The vibration absorber (13, 18, 25) according to claim 1, characterized in that in, The spoke spring is designed as a torsion spring rod.

6. The vibration absorber (13, 18, 25) according to claim 1, characterized in that For reducing the vibration characteristics of a specific crankshaft system (1) having a crankshaft natural frequency (4), wherein a first damper (6, 12, 19, 20, 21) has a first natural frequency and a second damper (6, 12, 19, 20, 21) has a second natural frequency, the first natural frequency being lower than the crankshaft natural frequency (4) and the second natural frequency being higher than the crankshaft natural frequency (4).

7. The vibration absorber (13, 18, 25) according to any one of claims 1 to 5, characterized in that For reducing the vibration characteristics of a specific crankshaft system (1) having a crankshaft natural frequency (4), wherein a first damper (6, 12, 19, 20, 21) has a first natural frequency, which differs from the crankshaft natural frequency (4) by a maximum of 10 Hz, wherein a second damper (6, 12, 19, 20, 21) has a second natural frequency, which differs from a maximum frequency (10, 11) of the frequency characteristic (9) of the crankshaft system (1) damped by the first damper (6, 12, 19, 20, 21) by a maximum of 20 Hz.

8. The vibration absorber (13, 18, 25) according to claim 6, characterized in that It also has at least one further damper (6, 12, 19, 20, 21) having a further natural frequency, wherein for each further damper (6, 12, 19, 20, 21) it is applicable that its further natural frequency differs by a maximum of 20 Hz from the frequency of the maximum value of the frequency characteristic of the crankshaft system (1) damped by the remaining dampers (6, 12, 19, 20, 21).

9. A crankshaft damper assembly, characterized in that: The assembly comprises a crankshaft having a crankshaft natural frequency and a vibration damper (13, 18, 25) according to any of the preceding claims, wherein a first damper (6, 12, 19, 20, 21) has a first natural frequency which is lower than the crankshaft natural frequency (4), and a second damper (6, 12, 19, 20, 21) has a second natural frequency which is higher than the crankshaft natural frequency.

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