Vibration damper assembly, method for adjusting such an assembly, and method for manufacturing a vibration damper assembly

Abstract

The frequency-tuned vibration damper assembly (100) includes a horn plate (20) connected to a vibration surface (3) of a steering wheel structure at a first interface (I1) via a plurality of first elastic damper elements (30) so as to be movable relative to the vibration surface (3). A mass (10) supported by the plate (20) is movable relative to the plate (20) on the opposite front side of the plate (20). A second interface (I2) between the plate (20) and the mass (10) includes an elastic buffer element (40). The stiffness of the elastic buffer element (40) is selected so that it forms a second elastic buffer element, which, together with the first elastic buffer element (30) and the mass (10), forms a frequency-tuned damped mass-spring system having two damping interfaces and is frequency-tuned to the vibration of the vibration surface.

Description

[Technical Field]

[0001] The present disclosure relates generally to the field of dynamically frequency-tuned vibration dampers for automotive vehicles. A dynamically frequency-tuned damper assembly for damping vibrations in a steering wheel structure is disclosed. Also disclosed are methods for frequency tuning such a vibration damper assembly and methods for damping vibrations in a steering wheel structure. Additionally, methods for manufacturing vibration damper assemblies that are frequency-tuned to mutually different frequencies are disclosed. The present disclosure also relates to the use of a resilient buffer assembly element in the frequency-tuned vibration damper assembly. [Background technology]

[0002] Dynamic frequency-tuned vibration damper assemblies typically include at least one mass acting as a vibrating body and one or more elastic damper elements, the mass being elastically connected to a vibrating surface via the elastic damper elements, the mass and elastic elements together forming a damped spring-mass system connectable to the vibrating surface.

[0003] The weight of the mass and the stiffness, damping, design, and number of the elastic damper elements constitute tuning parameters and are selected or varied to provide a damping effect on a vibrating structure that is expected to vibrate at one or more preset target frequencies. When the vibrating structure vibrates at the target frequencies, the mass or oscillator vibrates / resonates at essentially the same frequency as the structure, but out of phase, thereby substantially damping the vibrations of the structure. Depending on the application, frequency-tuned dampers can be tuned to different frequencies in different spatial directions.

[0004] Frequency-tuned vibration dampers, also known as tuned mass dampers, dynamic dampers, or vibration absorbers, function by using one or more elastic damper elements to transfer vibrations from a vibrating structure to at least one mass that vibrates out of phase to damp the vibrations, thereby canceling and reducing vibrations in the structure or surface to which the damper is connected. WO 01 / 92752 A1, WO 2013 / 167524 A1, and WO 2008 / 127157 A1 disclose examples of frequency-tuned vibration dampers.

[0005] In the automotive industry, some steering wheels are provided with frequency-tuned vibration damper assemblies to reduce steering wheel vibration caused by road or engine vibrations transmitted to the steering wheel. In such damper designs, the weight of a gas generator, also known as an inflator, may be used as at least a portion of the mass in the damper assembly's spring-mass system. For this reason, such prior art vibration dampers may be integrated with the steering wheel's airbag module.

[0006] The steering wheel also typically includes a horn actuation mechanism that allows the driver to activate the vehicle's horn. The horn actuation mechanism may include one or more springs, called horn springs, that return the horn actuation mechanism to its normal state after the horn has been activated.

[0007] WO2019 / 129512A1 discloses an example of a vibration-reducing damper structure for a steering wheel, including an elastomeric damper element disposed on a slider slidably mounted on a bolt shaft. The entire damper assembly includes a set of such damper structures, each containing an elastomeric damper element. Steering wheel vibrations are transmitted to an airbag assembly by another such elastomeric damper element for damping purposes. During horn activation, the slider can slide along the bolt shaft. A spring disposed on the bolt shaft compresses during horn activation and returns the slider to its normal position when horn activation ends.

[0008] Shortcomings of the prior art include challenges with frequency tuning, particularly those related to reaching low tuning frequencies. Tuning to a lower vibration frequency generally means selecting a lower stiffness for the elastic damper element supporting the mass. However, in certain applications and situations, selecting a low elastic stiffness can create other problems. In particular, in so-called modular dampers, where the dynamic damper assembly uses the weight of an airbag module as the primary part of its mass, selecting a low stiffness may be practically impossible. If too low a stiffness is selected for the elastic damper element, the mass supported by it will "sag" under its own weight and assume an undesirable, improper position. Furthermore, such an improper positioning of the airbag module may cause the internal structural components of the assembly to become visible in an undesirable manner. Summary of the Invention

[0009] In view of the above, it is an object of the inventive concept to address one or more of the above-mentioned shortcomings of the prior art.

[0010] According to a first aspect, there is provided a method of frequency tuning a vibration damper assembly for damping vibrations in a steering wheel structure, comprising: the vibration damper assembly comprises a mass and a contact plate having a front surface facing the mass and a rear surface arranged to face a vibration surface of a steering wheel structure, the contact plate being connectable to the vibration surface via a plurality of first elastic elements so as to be movable relative to the vibration surface; the mass is supported by the contact plate; The method includes the step of frequency tuning the damper assembly to various vibration frequencies of the vibration surface by both varying the stiffness of a first elastic element and varying the stiffness of a plurality of second elastic elements, the second elastic elements being disposed between the plate and the mass and in contact with the plate and the mass, and being elastically deformable in response to movement of the mass relative to the contact plate during damping operation of the damper assembly.

[0011] According to a second aspect, there is provided a frequency tuned damper assembly for damping vibrations in a steering wheel structure, the assembly comprising: a plurality of first elastic elements; a contact plate connectable to the vibration surface via a first elastic element so as to be movable relative to the vibration surface of the steering wheel structure; a mass supported by the contact plate for movement relative to the contact plate; a plurality of second elastic elements disposed between the plate and the mass and in contact with the plate and the mass such that each second elastic element is elastically deformable in response to movement of the mass relative to the contact plate during damping operation of the damper assembly; The mass and the first and second resilient damper elements are configured to cooperate to act as a damped spring-mass system tuned to vibration of the vibrating surface during damping operation of the damper assembly.

[0012] According to a third aspect, there is provided a method of damping vibrations in a steering wheel structure, the method comprising: connecting the contact plate to the vibration surface via a plurality of first elastic elements such that the contact plate is movable relative to the vibration surface of the steering wheel structure; connecting a mass to the contact plate such that the mass can move relative to the contact plate; disposing a plurality of second elastic elements between the contact plate and the mass and in contact with the contact plate and the mass such that the second elastic elements are elastically deformable in response to movement of the mass relative to the contact plate during damping operation; and configuring the first and second elastic elements to form, together with the mass, a frequency-tuned damped spring-mass system that is frequency-tuned to the vibration of the vibrating surface.

[0013] According to a fourth aspect, there is provided a use of a resilient buffer element in a frequency-tuned vibration damper assembly, comprising: the damper assembly comprises: a plate connected to the vibration surface of the steering wheel structure via a plurality of first elastic damper elements so as to be movable relative to the vibration surface; a mass supported by the plate on a front side opposite to the plate so as to be movable relative to the plate; and an elastic buffer element provided between the plate and the mass; The present invention is characterized in that an elastic buffer element is used as a second elastic damper element which, together with the first elastic damper element and the mass, forms a frequency-tuned damped mass-spring system whose frequency is tuned to the vibration of the vibration surface.

[0014] According to a fifth aspect, there is provided a method of manufacturing a plurality of frequency-tuned vibration damper assemblies for damping vibrations in a steering wheel structure, the plurality of damper assemblies being frequency-tuned to mutually different damping frequencies, the method comprising: The method includes, to manufacture each damper assembly of the plurality of damper assemblies, - providing a contact plate, the contact plate having a front surface, an opposite rear surface, and a plurality of mounting openings therethrough; - inserting a plurality of elastomeric damper elements into the mounting openings, the elastomeric damper elements being arranged to connect to a steering wheel structure that vibrates on the rear side of the contact plate; - attaching a mass to the front side of the contact plate; - disposing a plurality of elastomeric buffer elements as spacers between the mass and the contact plate, the elastomeric buffer elements being resiliently compressed in response to attaching the mass to the contact plate; The method includes, to frequency tune the plurality of vibration damper assemblies to the mutually different damping frequencies: - selecting a stiffness of an elastomeric damper element of each damper assembly of the plurality of damper assemblies, each stiffness being different from the stiffness of the elastomeric damper elements of the other damper assemblies; - selecting a stiffness of an elastomeric buffer element of each damper assembly of the plurality of damper assemblies, each stiffness being different from the stiffness of the elastomeric buffer elements of the other damper assemblies.

[0015] In a preferred embodiment, the mass may include an airbag module. The airbag module may typically include a gas generator, which provides the mass of the airbag module. By using the existing weight of the airbag module in the steering wheel structure as at least a portion of the mass of the spring-mass system, it is possible to reduce weight gain when designing the damper assembly. Additionally, the weight of other components, such as the weight of the contact plate, may also constitute a portion of the total mass in the frequency-tuned spring-mass system.

[0016] A common feature of the inventive concepts is that the overall dynamic damping action while an elastically suspended mass is arranged to oscillate out of phase with an undesired vibration utilizes two separate sets of elastic elements operating at two different "interfaces" of the damper assembly, but still operating together in the overall damping action, rather than using only a single set of elastic damper elements as in the prior art. The first interface is between the contact plate and the vibrating structure to which the damper assembly can be connected. The second interface is between the contact plate and the mass. The first set of elastic damper elements is arranged to operate at the first interface as part of the overall damped spring-mass system. The second set of elastic damper elements is arranged to operate at the second interface as part of the overall damped spring-mass system. The first and second sets of elastic elements are configured with the mass to form a frequency-tuned spring-mass system that is frequency-tuned to the vibration of the vibrating structure. The spring-mass system of the present invention can also be thought of as a coupled or series-coupled dynamic spring-mass system that includes two interacting or cooperating sets of elastomeric elements configured to form a complete overall frequency-tuned damping system with the masses. In many cases, this allows the frequency of the damper assembly to be adjusted to achieve the intended out-of-phase motion of the masses during damping operation. Typically, the act of "configuring" the elastic elements involves selecting / tuning / changing the stiffness of the elastic elements.

[0017] The present concept provides an advantage in that it allows for the design of vibration-damping assemblies that can be frequency-tuned to lower frequencies compared to conventional damping solutions that rely on a single set of elastic damper elements operating at a single interface between the contact plate and the vibration surface. By using a first set of elastic elements and a second set of elastic elements located at a second interface between the contact plate and the mass, and configuring and selecting the stiffness of the first and second elastic elements so that they all actively participate in the overall dynamic damping action, the entire spring-mass system can be tuned to lower frequencies without reducing the stiffness of the first elastic elements. This is advantageous because reducing the stiffness of the first elastic elements can lead to undesirable weight-related misalignment of various parts within the assembly. The first elastic elements may be positioned to not only perform a frequency-damping function but also to position the contact plate relative to the steering wheel structure. If too low a stiffness is selected for the first elastic elements, the contact plate with the mass attached thereto may "sag" to an undesirable default position due to the combined weight, potentially allowing the driver to view the internal structural components of the assembly in an undesirable manner. Also, the damping behavior may be adversely affected by misalignment of such components. The inventive concept makes it possible to avoid the undesirable compromise between, on the one hand, choosing a low stiffness in order to reach a low tuning frequency, with the consequences of potential misalignment, and, on the other hand, choosing a high stiffness in order to avoid misalignment, with the drawback of not reaching the desired low tuning frequency.

[0018] A mass (eg, an airbag module) can be supported by the contact plate such that it can move linearly and / or rotationally relative to the contact plate during damping operation of the damper assembly.

[0019] In some embodiments, the mass is arranged to undergo at least linear movement relative to the contact plate during damping operation of the damper assembly, and the second elastic element is arranged to undergo shear deformation in response to said linear movement. Such linear movement may be in a plane essentially parallel to the contact plate and essentially perpendicular to a major axis of the steering column (e.g., extending vertically and / or horizontally). In certain cases, the damper assembly is designed to damp different frequencies in different directions.

[0020] In some embodiments, the mass is arranged to undergo at least rotational movement relative to the contact plate during damping operation of the damper assembly, and the second elastic element is arranged to undergo alternating compressive / extensional elastic deformation in response to said rotational movement. In certain aspects, the mass can undergo a combination of both linear and rotational movement relative to the contact plate during damping operation.

[0021] Configuring the two sets of elastic elements typically involves changing or selecting both the stiffness of the first elastic element and the stiffness of the second elastic element to achieve a desired tuning frequency of the damping system. This configuration process can also be considered a tuning operation. The stiffness of the first and second elastic elements can be varied in various ways, and these methods can be combined. In some embodiments, the stiffness can be varied by changing at least the shear stiffness of each or some of the first and / or second elastic elements. In some embodiments, the stiffness can be varied by changing at least the material hardness. In some embodiments, the stiffness can be varied by changing the physical design and / or dimensions of the elastic elements. Varying the stiffness can involve changing the stiffness of individual elements, but can also involve changing the stiffness of multiple elements as a group, for example, by changing the number of elastic elements in a set. In a design process, for example, to frequency-tune the overall damper assembly to expected vibrations of the steering wheel structure, the stiffness of the first elastic element may first be selected to achieve a first "main" frequency level or interval, and then the stiffness of the second elastic element may be selected to fine-tune the assembly in smaller steps.

[0022] Preferably, the first elastic element and the second elastic element are both made from an elastomeric material such as rubber.

[0023] The first elastic element and the second elastic element may differ from each other in one or many ways, for example, with respect to structure, design, material, stiffness, dimensions, mounting, function, mode of operation, number, etc.

[0024] In some embodiments, the system may be configured such that the movement of the contact plate relative to the vibrating structure is greater than the movement of the mass relative to the contact plate during damping operation, while in other embodiments the situation may be reversed.

[0025] In some embodiments, the plurality of second elastic elements may comprise a solid or homogenous body of elastomeric material, while the plurality of first elastic elements may comprise more structurally designed elements, such as cylindrical or sleeve-shaped elements.

[0026] In some embodiments, the mass is connected to the contact plate via one or more connector elements that do not form part of the second elastic element. In such embodiments, the second elastic element may be disposed between the contact plate and the mass without mechanically supporting the mass on the contact plate. In some embodiments, all or at least a portion of the second elastic element is mechanically connected to only one of the contact plate and the mass and frictionally engages only the other of the contact plate and the mass. The engagement on either side ensures that the second elastic element can elastically deform in response to movement of the mass relative to the contact plate during damping operation. In alternative embodiments, the second elastic element may also function as a connector element mechanically connected to both the mass and the contact plate.

[0027] In some embodiments, the number of first elastic elements may be different from or the same as the number of second elastic elements. Typically, the number of first elastic elements may be 3 to 4 to accurately position the contact plate relative to the steering wheel structure. As an example, the number of second elastic elements may be 4.

[0028] The actual locations of the first and second resilient elements relative to the contact plate may vary in different embodiments. In some embodiments, the contact plate may include a mounting opening for receiving the first resilient element. In such embodiments, the first resilient element may be at least partially disposed on a rear side of the contact plate facing the vibration surface. In some embodiments, the second resilient element may be at least partially disposed on a front side of the contact plate facing the mass.

[0029] The location of the mass relative to the contact plate may also vary in different embodiments. In some embodiments, the mass may be positioned entirely on the front side of the contact plate, and the second resilient element may be positioned at least partially between the mass and the contact plate to contact the mass and the contact plate. In alternative embodiments, the contact plate may have a central opening for receiving a portion of the mass, and may optionally extend partially onto the back side of the contact plate.

[0030] In some embodiments, the plurality of second elastic elements can comprise elastic assembly buffers arranged to maintain a distance between the mass and the contact plate during the assembly process. Such buffers can be attached to and supported by the contact plate prior to assembly. When the mass is attached and connected to the contact plate by one or more separate contact elements, a front portion of the assembly buffer can be brought into frictionally engaged contact, optionally indirectly engaged, with the mass. During assembly, the assembly buffer can be slightly elastically compressed to be attached in a biased state between the mass and the contact plate. Such assembly buffers can advantageously accommodate tolerances and avoid undesirable direct contact between the mass and the contact plate. In such embodiments, in accordance with the concepts of the present invention, the stiffness of the second elastic elements is selected so that they act as both an active damper element forming the active portion of the overall frequency-tuned spring-mass system and a static assembly buffer in the absence of vibration.

[0031] In embodiments in which the second elastic element has the dual function of acting as a dynamic damping element and an assembly buffer, it may be advantageous to significantly reduce the stiffness of the second elastic element compared to situations in which only the buffer function is required. As a non-limiting example, a relatively high hardness of 80 Shore A may be selected to obtain only a static assembly buffer action, while a relatively low hardness, for example 60 Shore A or less, or optionally 40 Shore A or less, may be selected to obtain both a dynamic frequency-tuned damping function together with the mass and the first elastic element, and an assembly buffer function.

[0032] These and other features and advantages of the inventive concepts are set forth in the claims and are further explained in the detailed description of the preferred embodiments.

[0033] Explanation of terms In this disclosure, the act of "varying the stiffness" of multiple elastic elements should be interpreted as adjusting or adapting the elastic stiffness of a group of elastic elements so that the elastic elements are configured to actively participate and contribute to dynamic vibration damping. With respect to the second elastic damping element, the act of "varying the stiffness" typically means selecting a stiffness that is low enough for the second elastic element to work together with the first elastic element to perform the overall dynamic damping action.

[0034] In the present disclosure, a "contact plate" (also referred to in the art as a "horn plate") should be interpreted as a plate-like element, optionally a multi-part element, forming part of the horn actuation mechanism of the steering wheel structure, said contact plate being movable in one direction in response to horn actuation performed by the driver, and being biased in the opposite direction by a horn spring mechanism to return the contact plate to its default position after horn actuation. [Brief explanation of the drawings]

[0035] The inventive concept, some non-limiting preferred embodiments, and further advantages of the inventive concept will now be described with reference to the following drawings. [Figure 1] FIG. 1 shows a steering wheel of a vehicle. [Figure 2] FIG. 2 is an exploded front view of one embodiment of a vibration reduction damper assembly. [Figure 3] FIG. 3 is an exploded rear view of the damper assembly of FIG. [Figure 4] FIG. 4 shows the installation of the airbag module. [Figure 5] FIG. 5 shows the damper assembly mounted to the steering wheel structure. [Figure 6] Figures 6A and 6B are enlarged cross-sectional views showing the installation of the airbag module shown in Figures 4 and 5. Figure 6C shows the movement of the airbag module. [Figure 7] 7A and 7B show the second elastic element. [Figure 8] FIG. 8 shows the damper assembly in partial cross section. [Figure 9] FIG. 9 is a cross-sectional view of the main damper unit. [Figure 10] 10A to 10C show the movement of the contact plate at the first interface. [Figure 11] 11A and 11B show the linear movement of the airbag module at the second interface. [Figure 12] 12A and 12B show the rotational movement of the airbag module at the second interface. [Figure 13] FIG. 13 is a schematic diagram of the concept of the present invention. [Figure 14] 14A-14C show alternative embodiments of the second elastic element. [Figure 15] FIG. 15 shows an alternative embodiment of the first elastic element. [Figure 16]FIG. 16 shows another alternative embodiment of the first elastic element. DETAILED DESCRIPTION OF THE INVENTION

[0036] The present invention relates generally to the field of frequency-tuned vibration dampers, also known as dynamic dampers. Such dampers can be used to damp vibrations in a vibrating surface or structure, such as a vibrating component, such as a steering wheel or steering wheel structure of an automobile. A dynamic vibration damper comprises at least one mass acting as an oscillator and at least one elastic damper element. The at least one mass and the at least one elastic damper element together provide a damped spring-mass system and can be connected to the vibrating structure.

[0037] The weight of the mass and the stiffness and damping of the elastic damper element are selected to provide a damping effect on a vibrating structure that is expected to vibrate at one or more predetermined target frequencies. When the vibrating structure vibrates at the target frequencies, the mass is preferably vibrated / resonated at essentially the same frequency as the structure but out of phase with it so that the vibration of the structure is significantly damped. The mass can vibrate at an amplitude much greater than the vibration amplitude of the vibrating structure.

[0038] FIG. 1 illustrates a steering wheel 2 for a motor vehicle equipped with a frequency damper assembly 100 according to one embodiment of the inventive concepts. A Cartesian coordinate system is used throughout this disclosure, with the x-axis coaxial with the steering column, and the y- and z-axes corresponding substantially to the horizontal and vertical directions, respectively. This coordinate system is fixed relative to the steering wheel and damper assembly, and the orientation of the y- and z-axes may change as the driver turns the steering wheel. Radial and circumferential directions are referenced to the x-axis.

[0039] Vibrations from the road and engine may be transmitted to the steering wheel 2. These steering wheel vibrations may be perpendicular to the steering column, as indicated by arrows Vy and Vz in FIG. 1, and may also be along the x-axis, as indicated by arrow Vx. The steering wheel 2 is provided with a vibration reduction damper assembly 100 (FIG. 4) configured to dynamically damp at least some of the steering wheel vibrations. In particular, the components of the damper assembly 100 are selected to frequency-tune the damper assembly 100 to one or more of the "problem vibrations" to be damped.

[0040] As is known in the art, the steering wheel 2 also includes a horn actuation mechanism for activating the vehicle's horn (not shown). To this end, a horn actuation pad 4 is located in the center of the steering wheel 2, which is pressed by the driver when the horn is to be activated. A damper assembly is located behind the horn actuation pad 4. When the driver presses the horn actuation pad 4, an electrical switch is closed, activating the horn. The switch (not shown) may be in the form of, for example, one or more metal rivets supported by the armature 3 and which are in electrical contact with the horn plate 20 when the horn is activated. When the driver releases the horn actuation pad 4, the horn actuation mechanism is returned to its deactivated or initial state by one or more horn springs.

[0041] The airbag module 10, located in the center of the steering wheel 2, typically includes at least an inflatable airbag and a gas generator 11 (FIG. 5). In this embodiment, the weight of the airbag module 10, and in particular the weight of the gas generator 11, is used as at least a portion of the total mass of the frequency-tuned spring-mass system, thereby making it possible to avoid or significantly reduce the use of a separate weight for this purpose.

[0042] 2 and 3 are exploded perspective views illustrating the various components of a dynamic vibration reduction damper assembly 100 and its assembly to an armature 3 of a steering wheel structure, as indicated by dashed lines. The main parts of the entire damper assembly 100 include an airbag module 10 (forming at least a portion of the mass of a damping spring-mass system), a contact plate 20 (also referred to in the art as a horn plate), a plurality of first elastic elements 30, and a plurality of second elastic elements 40. The damper assembly 100 is disposed on and supported by a base structure or armature 3, to which the steering wheel 2 is fixedly connected. Vibrations of the steering wheel 2 are therefore also present in the armature 3. Thus, in this embodiment, the surface of the armature 3 facing the damper assembly 100 constitutes the vibration surface whose vibrations are to be damped.

[0043] The contact plate 20 can be made of metal or any other rigid material. It can extend parallel to the yz plane. It can include a plastic cover (not shown) made of a relatively rigid plastic material molded onto the horn plate 20, including top and bottom covers. The contact plate includes a plurality of openings 22, each positioned to receive an associated one of the first elastic damper elements 30, as described below. In the illustrated embodiment, a cylindrical sleeve is disposed around each opening 22 in the contact plate 14 and extends above the front side of the contact plate 14. The sleeve may be integrally molded with the plastic cover and thus rigidly connected to the horn plate 20. In other embodiments, the sleeve may be absent. The contact plate 20 further includes a plurality of smaller openings 24, each positioned to receive a portion of an associated one of the second elastic damper elements 40, as described further below. The contact plate 20 further includes two openings 26, spaced apart from one another along the horizontal z-axis, each positioned to receive an associated mounting element 12 attached to and projecting from the rear of the airbag module 10. FIGS. 2 and 3 further show three bolts 50, each positioned to be inserted through an associated one of the openings 22 and through an associated one of the first damper elements 30 and fixedly attached to the mounting studs 5 of the armature 3. Finally, FIGS. 2 and 3 show a locking spring 60 for engaging the mounting element 12 of the airbag module 10. The locking spring 60 is installed in a biased state. The first and second resilient elements 30, 40 may be fabricated from any suitable elastomeric material, such as silicone rubber.

[0044] As shown enlarged in FIG. 9 , each elastic damper element 30 is disposed around a tubular slider 70. In final assembly, the tubular slider 70 is positioned to slide along the shaft 52 of the bolt 50 during horn actuation. The slider 70 can typically be manufactured from a more rigid material. In the illustrated embodiment, the elastic elements 30 and slider 70 can be prefabricated as a single, integrated damper unit, hereinafter referred to as the “primary damper unit.” The elastic elements 30 can be molded directly onto the slider 70. This can be done by 2K injection molding, in which the slider 70 and the elastomeric component 30 are manufactured using a single 2K injection molding machine. Alternatively, the elastic elements 30 can be further bonded to the slider 70, such as by mechanical and / or chemical bonding.

[0045] In the assembly process shown in FIG. 3, each primary damper unit 30+70 is inserted rearward through the associated opening 22 in the contact plate 20. FIG. 9 shows the primary damper unit in the installed position. During insertion, the radially enlarged portion 34 of the elastic element 30 is radially deformed to pass through the opening 22 and then radially expanded to secure the elastic element 30 in place. The central portion of the elastic element 30 forms the engagement surface 34 that engages with the rim of the opening 20. This forms the interface through which vibrations from the armature 3 are transmitted. The rear end of the elastic element 30 engages a horn spring 80 biased between the primary damper unit and the armature 3.

[0046] Subsequently, during assembly, the shaft 52 of each bolt 50 is inserted through the associated opening 22 in the contact plate 20 and through the associated primary unit 30, 70. The threaded bolt end 54 is securely fastened to the mounting stud 5 of the armature 3. The contact plate 20 is thereby resiliently suspended from the armature 3 via the primary damper unit. During dynamic damping operation, the contact plate 20 is permitted to undergo an oscillatory motion relative to the armature 3, as shown by arrows Py and Pz in FIGS. 10A-10C. In some embodiments, oscillation may also occur in the x-direction.

[0047] During final tightening of each bolt 50, a pre-compression of the corresponding horn spring 80 is obtained. By way of non-limiting example, the horn spring 80 may be pre-compressed from 10 mm to 7 mm during assembly, and then compressed an additional mm or several mm upon horn actuation.

[0048] In the final assembled state, the bolt heads may axially engage the insertion ends 32 of the resilient elements 30, optionally with a slight axial resilient compression to lock the ends 32 in place. During final tightening of each bolt 50, the bolt heads may engage and axially compress the resilient elements 30 until their insertion ends are level with the distal ends of the sliders 70. This optional final compression locks the snap-lock projections 32 more tightly, thereby further securing the damper unit against the contact plate 20.

[0049] FIG. 7B illustrates the pre-assembly of the second elastic elements 40 on the front side of the contact plate 20. As described in more detail below, the second elastic elements 40 can have the dual function of both acting as active dynamic damping elements in the dynamic damping operation of the overall damper assembly 100 and acting as static assembly buffers. In this embodiment, there are four second elastic elements 40 arranged in a generally square configuration on the contact plate 20. Other numbers and configurations are possible. Each second elastic element 40 includes a main portion, an insert portion 42, and a mounting groove 44 located therebetween. In the illustrated embodiment, the main portion is slightly conical in shape, and the insert portion 42 is also conical in shape but with a more pronounced cone angle. In the pre-assembly process, the insert portion 42 of each second elastic element 40 is pulled or pushed through the associated mounting opening 24 of the contact plate 20 until the rim of the opening 24 engages the mounting groove 44 to hold the element 40 in place.

[0050] In the illustrated embodiment, the second elastic element 40 is manufactured as a solid or homogenous body, in contrast to the more sleeve-shaped first elastic element 30. The material may be silicone rubber or other suitable elastomeric material exhibiting the required stiffness.

[0051] Following the above-described attachment of the contact plate 20 to the armature 3 via the primary damper units 30, 70 and the above-described pre-assembly of the second elastic element 40 to the contact plate 20, the airbag module 10 can be attached to the contact plate 20. Figure 4 shows in dashed lines how the two rod-shaped mounting elements 12 of the airbag module 10 are aligned with the openings 26 in the contact plate 20. The airbag module 10 is moved towards the contact plate 20 until the conical insertion ends 14 of the mounting elements 12 are inserted through the openings 26. The final position of the airbag module 10 is shown in Figure 5.

[0052] 6A and 6B show a mechanism for preventing the airbag module 20 from disengaging from the contact plate 20. Other designs are possible. In this embodiment, engagement is achieved by a locking spring 60 and an engagement groove 16 formed in the mounting element 12. The locking spring 60 is installed in a biased state. As shown in FIG. 6A, when the tip 14 of the mounting element 12 is inserted through the opening 24, the ramp portion deflects the locking spring 60 laterally until it quickly returns to the engagement groove 16, as shown in FIG. 6B. In this position, the airbag module 10 is prevented from disengaging from the contact plate 20. However, as will be described below, the airbag module 10 can still move slightly relative to the contact plate 20.

[0053] In accordance with the concepts of the present invention, a second resilient element 40 engages both the contact plate 20 and the mass 10. In the illustrated embodiment, the engagement between the second resilient element 40 and the mass 10 is achieved solely by frictional forces. The second resilient element 40 is sized to be slightly compressed during final installation of the airbag module 10 as described above to achieve the frictional engagement between the second resilient element 40 and the airbag module 10. During assembly of the airbag module 10 to the contact plate 20, the second resilient element 40 can function as an assembly buffer to accommodate manufacturing tolerances and to prevent direct contact between the main parts of the airbag module 10 and the contact plate 20.

[0054] In accordance with the concepts of the present invention, this structure allows the airbag module 10 to undergo various movements relative to the contact plate during dynamic damping operation. The possible movements may vary between different embodiments. Figure 6C illustrates some of the key movements.

[0055] The first movement is linear or translational, as indicated by arrow Mz. In the illustrated example, the airbag module 10 (i.e., the main mass portion of the damping spring-mass system) is capable of linear movement in the vertical z-direction relative to the contact plate 20. This linear movement is made possible by the small radial annular play d between the mounting element 12 and the rim of the opening 24. The elastic spring characteristics of the locking spring 60 allow this movement while maintaining engagement with the mounting element 12. In some embodiments, linear movement in the y- and / or x-directions is also possible.

[0056] The second movement is a rotational movement as shown by the arrow Mr in Figure 6C. In the illustrated example, the airbag module 10 is capable of a rotational movement Mr relative to the contact plate 20 during damping. In this example, the axis of rotation is essentially determined by the point of engagement with the locking spring 60, i.e., by rotation relative to a horizontal axis along which the mass 10 moves slightly up and down during damping.

[0057] The overall dynamic damping operation of the inventive concepts will now be described in more detail with particular reference to FIGS. 10A-10C, 11A and 11B, 12A and 12B, and 13. FIG.

[0058] 13 is a schematic diagram, not to scale, illustrating the concept of the present invention. References I1 and I2 designate a first interface and a second interface, respectively. The first interface I1 is between the contact plate 20 and the armature 3, which exhibits the "problem vibrations" Vy and / or Vz. The second interface I2 is between the contact plate 20 and the mass 10, here provided by the airbag module 10. A first elastic element 30 is disposed at the first interface I1, and a second elastic element 40 is disposed at the second interface I2.

[0059] 13, each first elastic damper element 30 has a spring characteristic S1 and a damping characteristic D1, and each second elastic damper element 40 has a spring characteristic S2 and a damping characteristic D2. The spring characteristics S1 and S2 may be different from each other, and the damping characteristics D1 and D2 may be different from each other.

[0060] The mass, stiffness of the first elastic element 30, and stiffness of the second elastic element 40 of the airbag module 10 are configured such that, during dynamic damping operation of the damper assembly, the mass, first elastic element 30, and second elastic element 40 collectively operate as a frequency-tuned damped spring-mass system that is frequency-tuned to the vibration Vy of the vibrating surface or structure 3. In other words, the configuration is such that, during damping operation, the damper assembly 100 exhibits damped oscillatory behavior at both interfaces I1 and I2. The contact plate 20 experiences oscillatory motion (e.g., Pz) relative to the armature 3, and the mass 120 experiences oscillatory motion (e.g., Mz and / or Mr) relative to the contact plate 20. The weight of the contact plate 20 and other small components can also be considered part of the overall mass of the damper system.

[0061] Thus, in accordance with the inventive concept, the overall damping action includes not just damping action at one interface as in the prior art, but damping action at two different interfaces I1, I2 by two different sets of elastic elements, the stiffness of both sets of elastic elements being selected so that together, together with the mass, both sets form an overall "coupled" damped spring-mass system that is frequency-tuned to the vibration being damped.

[0062] During the design process, the stiffness of the elastic elements 30, 40 is modified / tuned in response to the expected frequency of vibration to be damped. The weight of the airbag module 10 must also be considered. Design parameters will typically be selected so that the airbag module 10 (i.e., the mass) vibrates at the vibration frequency of interest (e.g., Vz), but out of phase. During this movement, by appropriately selecting the stiffness of the second interface I2, a relative damping movement will occur not only at the first interface I1, but also at the second elastic element 40.

[0063] The arrows Py, Pz in Figure 10A indicate a possible linear damping movement of the contact plate 20 relative to the armature 3 at the first interface portion I1. During such movement, the first elastic element 30 will undergo elastic deformation, as known per se in the art. In this embodiment, the elastic deformation comprises a radial compression / extension of the central portion 34 of the elastic element 30. In some embodiments, there may also be a damping movement in the x-direction at the first interface portion I1.

[0064] The arrows My, Mz in Figure 11A indicate a possible linear damping movement of the airbag module 10 at the second interface I2 relative to the contact plate 20. During such linear / translational movement, the second elastic element 40 will undergo elastic deformation. As shown enlarged in Figure 11B, such elastic deformation is essentially a shear deformation of the element 40 when the mass 10 is moving horizontally and / or vertically relative to the contact plate 20. As mentioned above, there may simultaneously be a slight axial compression of the second elastic element 40 to ensure frictional engagement with the airbag module 10.

[0065] The arrows Mr in Figure 12A indicate possible rotational damping movements of the airbag module 10 at the second interface portion I2 relative to the contact plate 20. During such rotational movements Mr, the second elastic element 40 will primarily undergo alternating compression / extension, as shown in Figure 12B.

[0066] Whether the second interface I2 provides only linear / translational airbag module damping motion, only rotational motion, or a combination of both depends on several factors, including the characteristics of the vibration in question (frequency, amplitude, frequency variation, etc.), the number of resilient elements 30, 40, and their arrangement. With respect to motion in the x-direction, the locking spring 60 is preferably strong enough to keep the second resilient element 40 resiliently biased or compressed, so that the dynamic damping effect of the second interface I2 in this embodiment is mostly or completely limited to motion in the y- and z-directions and / or rotational motion.

[0067] As mentioned above, a particular advantage of the inventive concept is that by using two interacting sets of elastic damper elements 30, 40 operating at two different interfaces I1, I2, it is possible to reach a substantially lower tuning frequency without any adverse effects. By way of example, tests have shown that an assembly such as that described above, without using damping at the second interface, can reach a tuning frequency of approximately 32 Hz, while using a second set of elastic dampers 40 with a hardness of 40 Shore A in dynamic damping operation, it is possible to reach a tuning frequency of approximately 20 Hz, i.e., a reduction in frequency of approximately 40%.

[0068] In other words, the present invention makes it possible to reach a composite or overall dynamic system damping frequency that is X% lower than the lowest damping frequency that can be reached by the same set of first elastic dampers alone operating with the same design without combining it with the damping action of the second set of elastic dampers in the second interface portion I2, where X can be any of at least 10%, at least 20%, at least 30%, or more.

[0069] Alternative example The illustrated embodiment described above can be modified in many ways.

[0070] In the embodiment shown, the second elastic element is initially mechanically attached to the contact plate 20 and engages the mass 10 by frictional forces only. In alternative embodiments, a mechanically reversed solution may be used, or there may be mechanical / chemical engagement at both ends.

[0071] 14A-14C show a variation of the second elastic element 40'. In this alternative, the main portion of the element 40' is bellows-shaped and provides a plurality of circumferentially extending ribs or flanges 46'. The number and design of the flanges 46' constitute additional tuning parameters for varying the stiffness of the elastic element. Furthermore, both this and the previous embodiment can be varied in different ways. The element 40, 40' can be sleeve-shaped with an internal bore, the size and dimensions of which can constitute additional tuning parameters. The cross section of the element can also be varied.

[0072] 15 and 16 illustrate alternative embodiments of the first resilient element 30. FIG. 15 shows a ribbed first resilient element 130 providing multiple circumferentially distributed ribs 132 separated by spaces 131. The ribs 132 extend from the rear base of the element 1232 toward the front insertion end of the element 130. As with the previous embodiment, the resilient element 130 is molded onto the slider 70, which is made of a more rigid material. During molding, the element 130 is mechanically secured to the slider 70 through openings 75 formed in the flange 74 of the slider 70, and the resilient material at 136 secures the components 130 and 70 together. Each rib 132 has a radially enlarged portion at its insertion end, providing leading and trailing inclined surfaces 132a and 132b, as in the previous embodiment. While the snap-lock mechanism is essentially the same, the ribbed configuration allows for easier insertion of the contact plate into the opening 22. The ribbed configuration also provides additional adjustment options.

[0073] The resilient element 130 further comprises a first set of axial studs 134a having a first axial height and a second set of axial studs 134b having a second axial height less than the first axial height. The first studs 134a provide an insertion stop during insertion of the resilient element 130 into the contact plate opening 22. The studs 134a also provide a decoupling effect so that frictional engagement between the base of the element 130 and the back surface of the contact plate 20 does not interfere with damping. The second set of studs 134b is activated during horn actuation. As the contact plate 20 moves toward the armature 3 during horn actuation, the smaller studs 134a are axially compressed first. When they are flush with the larger, lower studs 134b, the two sets of studs 134a, 134b, cooperate to provide a more rigid axial stop against horn actuation movement. The embodiment of the first elastic element 30 shown in the previous figures can provide such a first stud and, optionally, also such a second stud.

[0074] This design, and the operation and advantages of the design of FIG. 15, are fully described in applicant's WO2019 / 129512A1, the disclosure of which is incorporated herein by reference.

[0075] Figure 16 shows a variation of the design of Figure 15, which also includes an integral horn spring 138 that is integrally molded with the resilient element 130 and can replace the separate spring 80 in the previous embodiment. Such an integral horn spring can also be used in ribless designs of the first resilient element 30.

[0076] In the embodiment shown, the guide shaft 52 is part of a bolt 50 that is screwed into the vibrating base structure 3. The guide shaft may also be realized in different ways, for example by a guide shaft made integral with the vibrating structure 3, optionally with a threaded free end for fixing the assembly by a nut. It is also possible in some embodiments for the bolt 50 to be oriented in the opposite direction, i.e. to be screwed into the horn plate instead.

[0077] In other embodiments, if the damper unit is configured to transmit vibrations only in a few specific directions, the outer engagement surface of the first resilient element 30, 130 may exist only in a few directions. This can be achieved in a variety of ways, such as by locating an inner protrusion in a mounting opening in the horn plate that defines a circumferentially limited inner engagement surface, such as an inner protrusion on a sleeve. It can also be achieved by designing the resilient damper element 30, 130 to have an engagement surface only in a few directions. In such embodiments, where a single damper unit is arranged to transmit vibrations only in a specific direction, the complete assembly can include multiple damper units arranged to handle vibrations in various directions.

Claims

1. 1. A method of frequency tuning a vibration damper assembly for damping vibrations in a steering wheel structure, comprising: the vibration damper assembly comprises a mass and a contact plate having a front surface facing the mass and a rear surface arranged to face a vibration surface of the steering wheel structure, the contact plate being connectable to the vibration surface via a plurality of first elastic elements so as to be movable relative to the vibration surface; the mass is supported by the contact plate; the method includes frequency tuning the vibration damper assembly to various vibration frequencies of the vibrating surface by both varying the stiffness of the first elastic element and varying the stiffness of a plurality of second elastic elements, the second elastic elements being disposed between the contact plate and the mass and in contact with the contact plate and the mass, and being elastically deformable in response to movement of the mass relative to the contact plate during damping operation of the vibration damper assembly; the second resilient element including a resilient assembly buffer positioned to maintain a distance between the mass and the contact plate.

2. 10. The method of claim 1, 10. The method of claim 9, wherein varying the stiffness of the second elastic element comprises varying at least a shear stiffness of the second elastic element.

3. 3. The method according to claim 1 or 2, 10. The method of claim 9, wherein varying the stiffness of the second elastic element comprises varying at least a material hardness of the second elastic element.

4. 4. The method of claim 3, The method is characterized in that the material hardness of the second elastic element is selected to be 60 Shore A or less.

5. 5. The method of claim 4, The method is characterized in that the material hardness of the second elastic element is selected to be 40 Shore A or less.

6. The method according to any one of claims 1 to 5, The method, wherein the mass comprises an airbag module.

7. 1. A frequency tuned damper assembly for damping vibrations in a steering wheel structure, comprising: a plurality of first elastic elements; a contact plate connectable to a vibration surface of the steering wheel structure via said first elastic element so as to be movable relative to said vibration surface; a mass supported by said contact plate so as to be movable relative to said contact plate; a plurality of second elastic elements arranged between and in contact with the contact plate and the mass such that each second elastic element is elastically deformable in response to movement of the mass relative to the contact plate during damping operation of the damper assembly; the mass and the first and second elastic damper elements are configured to cooperate to operate as a frequency-tuned damped spring-mass system that is frequency-tuned to vibrations of the vibration surface during damping operation of the damper assembly; The damper assembly according to claim 1, wherein the second resilient element includes a resilient assembly buffer positioned to maintain a distance between the mass and the contact plate.

8. 8. The damper assembly of claim 7, 10. A damper assembly according to claim 9, wherein the mass is connected to the contact plate via one or more connector elements that do not form part of the second elastic element.

9. 9. The damper assembly according to claim 7 or 8, 10. A damper assembly, comprising: a contact plate supporting the mass such that the mass can move linearly and / or rotationally relative to the contact plate during damping operation of the damper assembly.

10. The damper assembly according to any one of claims 7 to 9, 10. A damper assembly comprising: a mass body arranged to undergo at least linear movement relative to the contact plate during damping operation of the damper assembly; and a second elastic element arranged to undergo shear deformation in response to the linear movement.

11. The damper assembly according to any one of claims 7 to 10, 10. A damper assembly comprising: a mass body arranged to undergo at least rotational movement relative to the contact plate during damping operation of the damper assembly; and a second elastic element arranged to undergo alternating compression / extension deformation in response to the rotational movement.

12. The damper assembly according to any one of claims 7 to 11, at least some of the second resilient elements are mechanically connected to one of the contact plate and the mass and are in frictional engagement with the other of the contact plate and the mass.

13. The damper assembly according to any one of claims 7 to 12, The damper assembly, wherein the mass comprises an airbag module.

14. 10. A method of damping vibrations in a steering wheel structure using the damper assembly of claim 7, comprising: connecting the contact plate to a vibration surface of a steering wheel structure via a plurality of first elastic elements such that the contact plate is movable relative to the vibration surface; connecting the mass to the contact plate such that the mass can move relative to the contact plate; disposing a plurality of second elastic elements between the contact plate and the mass and in contact with the contact plate and the mass such that the second elastic elements are elastically deformable in response to movement of the mass relative to the contact plate during a damping operation; and configuring the first and second elastic elements to form, together with the mass, a damped spring-mass system that is frequency-tuned to vibration of the vibrating surface.

15. 15. The method of claim 14, the configuring step includes selecting a stiffness of the first elastic element and a stiffness of the second elastic element to frequency-tune the damped spring-mass system to vibrations of the vibration surface.

16. 8. Use of a resilient buffer assembly element in a frequency-tuned damper assembly according to claim 7, comprising: the damper assembly comprises: a plate connected to a vibration surface of a steering wheel structure via a plurality of first elastic damper elements so as to be movable relative to the vibration surface; a mass supported by the plate on a front side opposite to the plate so as to be movable relative to the plate; and an elastic buffer element provided between the plate and the mass; Use of an elastic buffer assembly element, characterized in that it is used as a second elastic damper element, together with the first elastic damper element and the mass, to form a frequency-tuned damped mass-spring system that is frequency-tuned to vibrations of the vibration surface.

17. 1. A method of manufacturing a plurality of frequency-tuned vibration damper assemblies for damping vibrations in a steering wheel structure, comprising: the plurality of vibration damper assemblies are frequency-tuned to mutually different damping frequencies; The method includes, to manufacture each vibration damper assembly of the plurality of damper assemblies, - providing a contact plate, said contact plate having a front surface, an opposite rear surface and a plurality of mounting openings therethrough; - inserting a plurality of elastomeric damper elements into said mounting openings, said elastomeric damper elements being arranged to be connected to a steering wheel structure vibrating on the rear side of said contact plate; - attaching a mass to the front side of said contact plate; - disposing a plurality of elastomeric buffer elements as spacers between the mass and the contact plate, the elastomeric buffer elements being compressed in response to attaching the mass to the contact plate; The method further comprises the steps of: - selecting the stiffness of the elastomeric damper element of each vibration damper assembly of said plurality of vibration damper assemblies to be different from the stiffness of the elastomeric damper elements of the other damper assemblies; - selecting the stiffness of the elastomeric buffer element of each vibration damper assembly of the plurality of vibration damper assemblies to be different from the stiffness of the elastomeric buffer elements of the other damper assemblies.

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