Device for the purpose of influencing the transfer of vibration between two units

The invention is a device for influencing transfer of vibration between two units, one is mounted so that it can vibrate and the other is mounted to be damped. A parallel circuit is connected indirectly or directly with both units, which comprises at least one elastically deformable element, with an associated first force path and at least one force generator, providing a second force path, oriented parallel to the first force path and associated with a lever, connected indirectly or directly with the one unit, which lever at one end is rotated about a first axis of rotation oriented orthogonally to both force paths.

CROSS REFERENCE TO RELATED APPLICATION

Reference is made to German Patent Application Serial No. 10 2012 004 808.4, filed on Mar. 9, 2012, which application is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

Field of the Invention

The invention relates to a device for the purpose of influencing the transfer of vibration between two units, one of which is mounted so that it can vibrate, and the other of which is mounted such that it can be damped, with a parallel circuit.

Description of the Prior Art

A device known as a dynamic anti-resonance force isolator is disclosed in U.S. Pat. No. 3,322,379, and serves to provide decoupling of vibration between a unit subjected to parasitic vibrations, and a unit that is to be damped with respect to the parasitic vibrations. In particular the device, by means of appropriate matching to the main frequency of excitation of the unit subjected to the parasitic vibrations, is able to isolate completely the unit that is to be damped with respect to the parasitic vibrations. For this purpose the device makes use of a mechanically driven pendulum as a force generator which is introduced in parallel to an elastically deformable support spring between the unit subjected to the parasitic vibrations and the unit that is to be damped. Such an anti-resonance force isolator arrangement of known art is schematically represented inFIG. 2. A unit1is mounted such that it can vibrate while being mounted opposite to a unit2that is to be damped. Thus the vibrating unit1represents a base plate, at whose center of gravity1san exciting force Feacts, directed in one dimension and in two directions, which sets the unit1into vibration. In the interests of a clearer representation a one degree of freedom system is supposed, in which force components that are oriented in two directions act between the two units1and2just along or parallel to a single force axis. For the purpose of vibration isolation, or vibration reduction, an elastically deformable support spring3is provided between the vibrating unit1and the unit2that is to be damped. The spring forms a first force path K1, along which both static and dynamic force components are transferred. Parallel to the support spring3, a force isolator, designed as a pendulum mechanism, is provided between the vibrating unit1and the unit2that is to be damped, by which inertial forces originating from the pendulum mechanism are introduced along a second force path K2that is oriented in parallel to the first force path K1. To this end the force generator provides a lever4, whose one end of the lever arm41is mounted such that it can rotate by a rotary bearing5about a first axis of rotation D1that is oriented orthogonally to both force paths K1and K2. For its part, the rotary bearing5is securely anchored via an attachment6with the unit2that is to be damped. At a distance r from the rotary bearing5, extending from the first axis of rotation D1, the lever4is mounted on a second rotary bearing7such that it can rotate about a second axis of rotation D2, which is oriented in parallel to the first axis of rotation D1. The second rotary bearing7is securely anchored via an attachment8with the vibrating unit1. A massive body9is attached on the end of the lever arm42that is mounted such that it can freely vibrate, and is opposite to the end of the lever arm41, which end of the lever arm42is distanced from the first axis of rotation D1by the lever arm length R. The body9is mounted such that it can pivot in two directions about the axis of rotation D2, and, as a function of the acceleration acting at the location of the body, generates an inertial force FTacting along the second force path K2in the direction of deflection. It is necessary to select the inertial force FTthat can be introduced along the second force path K2with respect to magnitude, frequency and phase such that the inertial forces FTacting along the second force path K2fully compensate for, and thus eliminate, the resonance forces Fresacting in the event of resonance along the first force path K1via the support spring3between the resonantly vibrating unit1and the unit2that is to be damped. The mode of operation that underlies the force generator, which is designed as a lever mechanism, thus operates so that the lever mechanism as a function of its inertia is set into anti-resonance compared with the resonant vibration behavior of the vibrating unit1. As a result of the dynamic component of the spring force Fresand the dynamic force being generated by the force resonator, by virtue of the relative movement between the vibrating unit1and the unit2that is to be damped, act in opposition and with equal strength at the location of the center of gravity2sof the unit2that is to be damped. Thus a maximum isolation of vibration between the vibrating unit1and the unit2that is to be damped is present at a fixed prescribed resonant frequency, to which the anti-resonance frequency of the force generator is set by the adjustment of particular parameters describing the kinematics of the lever mechanism. To this end it is in particular necessary to coordinate the following parameters with one another: the mass of the unit2that is to be damped, the mass of the massive body9, the spring stiffness k of the at least one support spring3, the lever ratio QR=R/r, and the massive moment of inertia J of the lever arm4.

SUMMARY OF THE INVENTION

The invention is a device for influencing the transfer of vibration between two units, with one unit being mounted so that it can vibrate and the other unit is mounted such that it can be damped. A parallel circuit is connected indirectly or directly with the two units, comprising at least one elastically deformable element and at least one force generator, which a lever arm mechanism such that the anti-resonant vibration behavior of the force generator can be adaptively matched to altering resonance properties of the vibrating system. The exertion of influence onto the force generator is to be undertaken without manual intervention, and must be capable of implementation in situ on the basis of an adaptive controller. In this manner vibration isolation must always remain ensured in the event of resonance, even if the resonant frequency alters. Moreover further influence of the transfer that is transmission, of vibration must also be provided above the isolation frequency.

In accordance with the invention, two units are connected indirectly or directly with both units, comprising at least one elastically deformable element, with which a first force path is associated, and at least one force generator, with which a second force path, oriented in parallel to the first force path, is associated, and which has a lever arm, connected indirectly or directly with the one unit, which can rotate about a first axis of rotation, which is oriented orthogonally to both force paths, which lever arm at a distance r from the first axis of rotation is connected indirectly or directly with the other unit such that it can rotate about a second axis of rotation, oriented in parallel to the first axis of rotation, and which provides an end of the lever arm that is fitted with a mass, and is mounted such that it can vibrate freely.

In accordance with the invention a device for the purpose of influencing the transfer of vibration between two units, has at least one actively controllable element in one lever arm region alongside the lever, between a second axis of rotation and an end of the lever arm that is mounted such that it can vibrate and is fitted with the mass, which includes an actively controllable element dynamically influencing the moment of inertia associated with the end of the lever arm that is mounted such that it can rotate about the second axis of rotation and is fitted with the mass.

The moment of inertia and the vibration dynamics of the force generator, are essentially determined by the dimensions of the lever arm, measured from the second axis of rotation up to the end of the lever arm that is fitted with the mass, and also by the mass that is provided or attached at the end of the lever arm. By exerting influence with an actuator on at least one of the above parameters, it is possible to influence the vibration behavior and thus the dynamic reactive effect of the force generator on the parasitic vibrations from the vibrating unit acting on the force generator.

Examples of embodiments are described, in which by exerting influence with an actuator onto the force generator the anti-resonance frequency can be varied and thus adjusted within a prescribed range of frequencies to the current exciting frequency of the vibration from the vibrating unit that is to be isolated. By means of suitable active control of the at least one actively controllable element that interacts with the force generator, it is possible to adapt the anti-resonance isolation frequency, so that in this manner it can counteract effectively the resonances of the system that vary as a function of operational conditions. It is self-evident that the transfer or transmission of vibrations from the vibrating unit onto the unit that is to be damped must also be influenced in a positive manner above the anti-resonance isolation frequency.

DETAILED DESCRIPTION OF THE INVENTION

Underlying all forms of embodiments of the invention, for an adaptively dynamic anti-resonance force isolator between a vibrating unit and a unit that is to be damped, is a force generator having the lever arm mechanism illustrated inFIG. 2, which provides an inertially-conditioned resonant vibration behavior with amplitude, frequency and phase matched for the purpose of complete elimination of the system-conditioned natural frequency of the vibrating unit. In the case of natural vibration of the vibrating unit, the lever arm mechanism generates counter-vibrations with exactly the same frequency and amplitude as the systemic natural vibrations of the vibrating unit which are displaced in phase by exactly 180° so that the resonant natural vibrations of the vibrating unit and the vibrations generated by the force generator at the location of the center of gravity of the unit to be damped are mutually eliminated.

In order to be able to adjust the anti-resonant vibration behavior of the force generator, a lever arm mechanism adaptively alters resonance frequencies of the vibrating unit in situ. dynamically during system operation. The lever arm mechanism illustrated inFIG. 1provides an actively controllable element10alongside the lever arm4H, which at one end is bounded by the second axis of rotation D2, and at the other end by the preferably freely-vibrating end of the lever arm42that is fitted with the mass. The actively controllable element10, when it is activated, induces a mechanical compressive or tensile stress into the lever arm4H. The stress deforms the lever arm4H at least in the region of the actively controllable element10. As a consequence, the stress influences at least the end of the lever arm that is fitted with the mass rotating about the second axis of rotation D2such that the end of the lever arm4H is accelerated in two directions longitudinally relative to the force paths K1, K2by a magnitude a and as a consequence is in each case deflected by a displacement of magnitude w.

In order to increase the effectiveness of the at least one actively controllable element so as to increase its ability as an actuator to deform the lever locally, it is advantageous to reduce the structural strength of the lever in the region of the actively controllable element. One form of reducing structural strength is by local thinning of the lever material.

The transducer materials of variable length are suitable in principle for the purpose of implementing the actively controllable element actuators. These transducer materials are produced, for example, from piezoelectric materials, magnetostrictive materials and/or from shape memory materials. Such actuators can be applied onto the surface of the lever, which is preferably produced from a metallic material, using a fiber composite material, such as, for example a material reinforced with glass, carbon, aramide or natural fibres, or from hybrid material compositions. In the case in which the lever is produced using fiber-reinforced materials, the fiber-reinforced composite materials that are suitable are primarily those with orthotropic properties, which have directionally-dependent elasticity properties, but do not possess any coupling between strains and shear deformations.

Also it is appropriate to integrate the actuators into the lever such that the actuators are protected from external influences. An integral design of the sensors and actuators within the composite structure is linked with the following advantages:

protection of the sensors and actuators from environmental influenceselimination of any additional structures for attaching and housing the actuators and sensors and any therewith linked production and assembly effort (reduced complexity)direct deformation coupling between the active element and the structure, andmodularity, by virtue of the construction of a closed, functionally integrated unit.

In the case of the actuator design inFIG. 1, it is assumed that the lever arm4H, has a cross-section of rectangular design, which provides on both its upper and lower faces an actively controllable element as close as possible to the location of the axis of rotation D2. Each element has the form of a piezoelectric actuator10of planar design. The two actuators10are controlled on the basis of an objective function of a control unit11. The function controls the state of vibration of the mass9connected with the end of the lever arm42. A sensor12serves to sense and register the state of vibration of the end of the lever arm42that is fitted with a mass. The sensor is preferably designed as a displacement sensor or an acceleration sensor. Relative vibrations between the vibrating unit and the unit that is to be damped can also be registered by sensors to obtain control signals for the control of the actuators.

In principle, it is also possible to arrange the at least one actively controllable element alongside the lever4between the two rotary bearings5and7. However, in the following discussion, it will be assumed that the actively controllable elements10are applied alongside the lever arm4H as close as possible to the location of the axis of rotation D2of the rotary bearing7.

The actively controllable elements10, which are designed as planar actuators, are able by means of alterations of their length, which are matched, to translate the lever arm4H from the horizontally straight shape represented inFIG. 1into a shape that is curved upwards4oor downwards4u, as indicated by the dashed lines representing each case4oand4u.

For the case in which the lever arm4H is deformed upwards, the actuators of planar design are controlled such that the actuator applied onto the upper face of the lever arm4H is shortened, whereas the actuator attached onto the lower face of the lever arm4H is lengthened. In this manner the surface on the upper face of the lever arm4H in the region of the actuators experiences a tensile stress that shortens the surface, whereas the lower face of the lever arm4H experiences a compressive stress, and/or tensile stress, that lengthens the surface locally. As a consequence, the lever arm4H is locally deformed in the region of the actuators for the purpose of exerting the above-described upward movement. In the reverse case, it is equally possible to deflect the lever arm4H downwards as indicated by position4u.

As a result of the above-described deflection of the lever arm4H that can be initiated by actuators, the mass9arranged at the end of the lever arm42experiences an acceleration oriented upwards or downwards, depending upon the deflection movement, about the second axis of rotation D2shown inFIG. 1. Thus it is possible to impose additionally on the mass9mounted at the end of the lever arm42, which is influenced by the vibrating unit1and the lever arm mechanism inertially-conditioned vibrations about the axis of rotation D2, suitably superimposed acceleration forces. These actions effect inter alia a virtual alteration of the mass9, as a result of which the moment of inertia of the lever arm arrangement oriented about the second axis of rotation D2can be altered, as can its resonant vibration behavior, and, linked with this is the anti-resonance frequency of the force generator.

The control of the actuators is undertaken by the control unit11, which on the basis of a programmed objective function prescribes the vibration isolation effect of the lever mechanism between the two units1and2.

It is self-evident that a combination of the above measures is also possible, which leads to improved behavior over the complete frequency range.

For the controlled superimposed acceleration of the end of the lever arm42that is fitted with the mass about the second axis of rotation D2, as can be seen inFIG. 1, further alternative configurations and attachments of actively controllable elements, in or relative to the lever arm4H, are suitable, as can be seen in the further embodiments. In the interest of simplifying the further description just the lever arm mechanism is illustrated, comprising the lever4, which is mounted such that it can rotate on the rotary bearings5and7about the first and second axes of rotation D1and D2respectively, and at whose end42the mass9is attached.

In the case ofFIG. 3an actuator10, having a thickness which can be altered, is introduced between the end of the lever arm42and the mass9. When the actuator is activated, it increases or decreases the distance d of the mass9relative to the lever4. In an equivalent manner, the actuator10is thus able to accelerate the mass9by a magnitude a along the force paths upwards or downwards, as a result of which, with suitable activation of the actuator10, a virtual reduction or increase of the mass can be achieved. In a similar manner to the above embodiments, this embodiment is able to influence the moment of inertia of the lever4about the axis of rotation D2, and, associated with the latter, the anti-resonance frequency. Alterations of the thickness of actuators consisting of piezoelectric material are typically limited. In order to increase the actuator travel of piezoelectric actuators in particular, gearing units or travel ratio mechanisms that increase the actuator travel are suitable which can be provided in the form of an actuator unit between the end of the lever arm42and the mass9. Such gearing units are known to the person skilled in the art, for example in the form of mechanical lever arm mechanisms, which are not the subject of the invention.

A further alternative for accelerating the mass9attached at the end of the lever arm and, associated with this, for exerting an active influence on the alteration of the location of the mass9relative to the force paths K1and K2, provides for the utilization of externally applied electrical and/or magnetic alternating fields. InFIG. 4it is supposed that the mass9consists of a permanently magnetic material. An electromagnetic arrangement with alternating magnetic polarity serves as an actively controllable element10which provides magnetic forces H acting on the permanently magnetic mass9, deflecting it upwards or downwards depending upon the magnetic polarity. Alternatively it is possible, instead of using magnetic forces H, to mount the mass9within a condenser unit10, in which an electric alternating field E is applied to provide electrically attracting or repelling forces which are able to accelerate the mass9in the above manner in two directions along the force paths K1and K2.

InFIG. 5is illustrated a mechanical solution for the generation of forces in two directions for accelerating the mass9along the force paths K1and K2. In this case, the end of the lever arm42is connected with an out-of-balance exciter in the form of a motor-driven eccentric unit13; this generates acceleration forces, which are at least oriented in two directions along the force paths K1and K2.

All of the embodiments elucidated inFIGS. 1, 3, 4 and 5contain actively controllable elements which produce acceleration forces acting on the mass9, acting along the force paths K1and K2, as a result of which the virtual mass, which is responsible for the dynamic moment of inertia of the lever arm4H about the axis of rotation D2, can be varied.

A further option for exerting an influence on the moment of inertia of the lever arm4H oriented about the second axis of rotation D2provides variation of the length (R-r) of the lever arm4H (cf.FIG. 1). InFIG. 6a lever arm arrangement is illustrated with a lever arm4H, alongside which an actively controllable element10is provided. The latter is able to lengthen or shorten the lever arm4H and as a consequence positions the end of the lever arm42that is fitted with the mass nearer or further from the location of the second rotary bearing D2. A possible form of implementation of the active element which is illustrated inFIG. 6relies upon a part of the lever arm4H from an actively controllable transducer material of variable length, from a piezoelectric or a magnetostrictive material, for example. The advantage of such materials is in their utilization of the property of shape alteration that is inherent to the material which enables a direct conversion of electrical or magnetic energy into deformation energy. Moreover such materials offer the option of implementing very compact designs in comparison to standard drives, for example. Since, however, the travel or length alteration caused by the shape alteration is limited, it is also appropriate to provide as an actively controllable element10a spindle mechanism that can be driven by an electric motor for the purpose of altering the length of the lever arm4H.

A further form of embodiment for the purpose of varying the lever arm length (R-r) uses the option of mounting at least one means of attachment8, seeFIG. 7, such that it can move linearly transverse to the track of the force paths K1and K2, with the aid of a motor-driven linear drive10, for example. In this manner the distance r between the first and second axes of rotation D1and D2can be varied, and thus the lever arm length R-r.

The device in accordance with the invention for the purpose of providing vibration isolation between a vibrating unit, structure, or component1and a unit, structure, or component2that is to be damped, can preferably be deployed for the purpose of vibration reduction between a motor unit and a structure supporting the motor unit. In particular in land, water or air vehicles the vibration-isolating device can contribute to the damping of vibrations of the bodywork of the motor vehicle or rail vehicle, or of the hull of a ship, or of an aircraft structure. The vibration damping measures contribute not only to the comfort of using the respective means of transport, in particular they also increase significantly the operating lives of components that are subjected to vibration. The measures in accordance with the invention for reducing or compensating for vibrations also enable components subjected to vibration to be designed less massively, especially since the components are subjected to lower mechanical loads.

The device in accordance with the invention is also suitable for reducing the vibration of at least one component or structure that is sensitive to vibration relative to a vibrating environment, such as, for example, a vibrating supporting structure. Such applications find deployment in particular in the technology of precision measurements, microscopy, and chip production.

FIGS. 8 to 10reproduce a summarizing overview on the basis of equivalent mechanical circuit diagrams in the form of pictograms, of respectively preferred examples of application and deployment for the device in accordance with the invention, for the purpose of influencing the transfer of vibration between two units.

FIG. 8shows the case in which the force generator is designed as an actively controllable lever arm mechanism functioning as an active bearing that is attached between a first unit1* and a second unit2*. Here the first unit1* is at rest, that is, securely anchored, and the second unit2* is mounted such that it can vibrate relative to the first unit1*. By means of suitable control, for example, by means of time-wise periodic control of the actively controllable element10, bearing forces F1, F2can be generated on both units, which, by virtue of the mounting of the second unit2* such that it can vibrate, lead to its spatial deflection in two directions. By means of a suitable lever arm length ratio the bearing force F2acting on the second unit2* can be selected to be greater than the bearing force F1acting on the first unit1*. Moreover the stiffness c and the damping action b of the active bearing can be prescribed by means of at least one elastically deformable element3attached between the two units1*,2*.

FIG. 9shows an inertial mass actuator, with which the unit M2*, which is fitted with a mass and mounted such that it can vibrate, is mounted in a freely vibrating manner on the structure1** that is to be influenced, and interacts with the force generator designed as a lever arm mechanism such that forces FIMAthat initiate vibration act upon the unit1** that is mounted such that it can vibrate, via the actively controllable lever mechanism. In this case also, the stiffness c and the damping action b can be prescribed by means of at least one elastically deformable element3attached between the two units M2* and1**.

FIG. 10shows the case of an adaptive dynamic vibration absorber, whose task it is to extract vibration energy from a vibrating system2, and preferably to convert this energy into another form of energy, preferably to dissipate it. For this purpose, the unit2that is to be damped is connected via at least one elastically deformable element3* with a vibrating system14, which thus excites the system2into undesired vibrations. The unit2that is to be damped is connected via an actively controllable lever mechanism with a unit M2* that is mounted such that it can vibrate freely. With the aid of the actively controllable element10alongside the lever arm4H, the resonant vibrating behavior of the lever arm mechanism is to be adjusted precisely such that the vibrating system2provides maximum vibrational excitation of the mass M2*, as a result of which a maximum of vibration energy is extracted from the vibrating system2. In this case also, the stiffness c and the damping action b can be prescribed by means of at least one elastically deformable element3attached between the two units2, M2*.

REFERENCE SYMBOL LIST

1Vibrating unit2Unit that is to be damped3Elastically deformable element, support spring4Lever4H Lever arm41End of the lever arm42End of the lever arm that is fitted with a mass5First rotary bearing6Means of attachment7Second rotary bearing8Means of attachment9Mass10Actively controllable element11Control unit12Sensor13Out-of-balance exciter14Vibrating systemK1, K2Force pathr Distance between first and second axes of rotationR Length of the lever41sCenter of gravity of the vibrating unit2sCenter of gravity of the unit that is to be dampedFTForce exerted by the force generator3* Elastically deformable element2* Unit mounted so it can vibrate1* Unit securely mounted at rest1** Structure that is to be influencedc Stiffness of the elastically deformable element3d Damping of the elastically deformable element3F1Bearing force generated by the actively controllable element10, introduced via the attachment8F2Bearing force generated by the actively controllable element10, introduced by means of attachment6FIMAInertial mass actuator forceM2* Unit that is fitted with a mass and mounted such that it can vibrate