Dynamic damper

The invention relates to a vibration damper with variable Resonant frequency of a dynamically excited component, according to the preamble of claim 1 and 5 respectively.

A vibration damper of this type can be used anywhere where a periodic excitation of a component is to be compensated, in particular in helicopters to vibration phenomena in helicopter, eg cockpit parts from the rotor system of the helicopter with the rotor rotational frequency are energized effort to counteract.

For modern helicopters, which operated with a variable rotor speed be, mass damper with a variable resonance frequency are required. For this purpose it is known, vibrating at the outer Inertial mass of a leaf spring-mass system by means of an electric motor controlled actuator differential masses longitudinally to move the leaf spring assembly to thereby form the natural frequency of the Vibration absorber continuously at the excitation frequency of the rotor system adapt. Such Frequenzverstellmechanismus in swinging Part of the spring-mass system is, however, a relatively large constructional connected and subject to high accelerations at high numbers of load cycles, so that life may experience problems.

The object of the invention is to provide a vibration damper of the aforementioned to create kind of a structurally simple and troublefree Resonance frequency adjustment in non-vibrating portion of the spring-mass system features.

This object is by the in claim 1 or 5 Damper marked resolved.

According to the invention due to the claimed, between housing and Leaf spring assembly effective support with variably adjustable Einspanngeometrie or spring rigidity ensures that the bending elasticity the spring assembly and thus the resonance frequency of the vibration absorber Only by a housing-side, ie in non-vibrating change region of the spring-mass system arranged mechanism leaves and thus structurally complicated and dynamically highly stressed mass displacement drives, the integrated into the vibrating part of the system are, ceased to exist.

In a further, particularly preferred embodiment of the invention is the Einspanngeometrie the support according to claim 2 characterized changed, that the leaf spring arrangement comprises at least two superposed on includes the part of the inertial mass firmly connected individual springs, whose mutual distance at the fixing means of the support transversely variably adjusted to the plane of the leaf spring assembly is. Such a distance-variable support of the double leaf spring can be by way of the resistance to bending moment Bending stiffness and thus the resonant frequency of the spring-mass system in a structurally particularly simple manner by the housing side control interventions influence.

According to a further preferred embodiment according to claim 3 of the invention, the verwenbar for vibration damper with a single leaf spring is the effective leaf spring length and thus resonant frequency influenced by a variable length Einspanngeometrie in such a way that the housing-side support of the leaf spring two each on a leaf spring side variable clamping includes fitting printed documents which in structurally useful embodiment of claim 4 each consist of a in Direction of the leaf spring assembly convex curved, in a variable-length Contact zone to the leaf spring assembly is repressed tension spring consist.

In the second variant of the invention, the resilient support according to claim 6 for reasons of structural simplification preferably each mechanical springs with non-linear spring curve and variably adjustable preload, whereby instead as support springs of coil springs, of course, non-metallic spring elements, about gas springs used with variably adjustable spring rate can be.

With regard to a simple design of the adjusting mechanism for Amending Einspanngeometrie or spring stiffness is this according Claim 7 preferably consists of a rotatable mounted on the housing Lead screw and two opposite directions at a rotational change in position of the spindle to one another transversely to the surface extension of the leaf spring assembly adjustable support members.

according to claim 8, the vibration absorber is preferably provided with a control unit , through which the resonance frequency of the vibration absorber adaptively changes the excitation frequency is readjusted.

The invention will now by means of embodiments in conjunction explained in more detail with the drawings. Shown schematically in strong illustration:<dl tsize="7"><dt><b>Fig. 1</b></dt><dd>a first embodiment of a passive vibration absorber with a variable length Blattfedereinspannung,</dd><dt><b>FIG. 2</b></dt><dd>the operating principle of a second embodiment with a double leaf spring and in terms of flexural modulus variable Blatteinspannung; </dd><dt><b>Fig. 3</b></dt><dd>a more detailed illustration of the embodiment of FIG. 2; and</dd><dt><b>Fig. 4</b></dt><dd>a of Fig. 3 corresponding view of a third embodiment the invention.</dd></dl>

According to FIG. 1 is a passive vibration damper 2 with its housing 4 fixed with a direction of the arrow A periodically excited component 6, about the Instrument panel of a helicopter cockpit, which the rotor system is excited by the rotor rotational frequency oscillations, connected and contains a clamped leaf spring 4 to the housing 8, at the free ends each one vibratory direction of the arrow A inertial mass 10 is attached. That of a leaf spring arm and an inertial mass 10 existing spring-mass system 12 is through to the component 6 offset acting exciting forces in vibration and for the eradication of Exciting forces it is necessary that the resonance frequency of the spring-mass system 12 matches the excitation frequency, ie for frequency variable Component excitations so as for helicopters whose rotor system is operated with variable speed, the resonance frequency must be of Vibration absorber 2 are changed in accordance with the excitation frequency.

To this end, the leaf spring 8 is on the housing 4 by means of a total of clamped with 14 designated support which a variably adjustable Einspanngeometrie possesses. In detail, the support 14 from a rotatably supported adjusting spindle 4 on the housing 16, with the two each arranged on a leaf spring side, axially movable, but rotationally fixed guided on the housing 4 support members 18 on opposite adjustment threads are screwed. In the case of a rotation of the lead screw 16 Consequently, the two support members 18 transversely and symmetrically to the surface extension the leaf spring 8 is traveling on these increases or from this. clamped the leaf spring 8 between likewise leaf spring-like, convex in Direction of the leaf spring 8 domed thrust pieces 20 in the middle Range screwed to the leaf spring 8 and the housing 4 and at their Ends are longitudinally displaceably mounted on the support members 18th Will the twisted adjusting spindle 16, the plungers 20 on the support members 18 - depending on the direction of rotation of the lead screw 16 - more or weaker pressed against the leaf spring 8, and accordingly changes the length of the contact and clamping region between the pressure pieces 20 and leaf spring 8, with the result that the free leaf spring length and thus also be considered for the resonance frequency of the vibration absorber reduced bending stiffness of the leaf spring 8 or increased accordingly.

For continuous adjustment of the resonance frequency of the vibration absorber 2 to the excitation frequency is a control unit 22 having a the Excitation frequency receiving sensor and an electric motor 24 provided of the adjusting spindle 16 in accordance with of the control unit 22 generated control signals rotationally positioned.

In the vibration damper according to Figs. 2 and 3 where the first embodiment functionally identical components by the same reference numerals are marked, there is a leaf spring 8 from two superimposed, 10 firmly connected to the side of the inertial mass Single springs 8.1 and 8.2, whose mutual distance on the housing side at the Clamping means of adjustable, from spindle 16 and Support members 18 existing support 14 transversely to the surface extension of the leaf springs 8 can be variably adjusted. When changing the Spring distance at the clamping point changes the flexural modulus and in turn the flexural rigidity of the double leaf spring 8 and thus the resonance frequency of the spring-mass system 12. As shown in Fig. 3 in the individual displays, in this embodiment, the support members 18 are each in two parts from the interposition of the leaf spring element 8.1 or 8.2 screwed together, plate-shaped supporting elements formed and by plate spring 26 in a play-free contact with the thread Adjusting spindle 16 is held and axially by means of securing pins 28 slidably but non-rotatably guided on the housing 4th Incidentally corresponds the construction and operation of the vibration absorber 2 according to FIGS. 2 and 3 of the first embodiment.

In the vibration damper according to Fig. 4, where again the previous Embodiments functionally identical components by the same reference numerals are marked, the leaf spring 8 with invariable Einspanngeometrie the housing 4 is clamped. For resonance adjustment the vibration damper 2 is in addition to the clamping point and the distance of this resilient support 30 provided for each leaf spring arm. The support 30 includes on each side of the leaf spring 8 between a the latter and the yoke-shaped support member 18 acting supporting spring 32, which - as by the changing wall height of the individual spring coils indicated - has a non-linear spring characteristic. Will the Support members 18 by rotation of the lead screw 16 in the same manner as in opposite directions in the embodiments described above, axially adjusted, so changes the bias of the support springs 32 and thus also their spring stiffness. This will increase or decrease the Rigidity of the overall spring system 8, 32 and consequently the resonant frequency the vibration damper. 2

For adaptive adjustment of the vibration absorber 2 at the instantaneous excitation frequency is in turn a control unit 22 having a motor Drive 24 for rotational positioning of the adjusting 16th in the Otherwise, the construction and operation of the vibration damper 2 of FIG. 4 the same as in the first two embodiments.