GB2599614A

GB2599614A - Active tuned vibration absorber

Info

Publication number: GB2599614A
Application number: GB2008396.0A
Authority: GB
Inventors: Mcgregor Stothers Ian; Bayliss Clive; Spence Myles; Anthony Colavincenzo Stephen; Kathirchelvan Thineshan
Original assignee: Bombardier Inc; De Havilland Aircraft of Canada Ltd; Ultra Electronics Ltd
Current assignee: Bombardier Inc; De Havilland Aircraft of Canada Ltd; Ultra Electronics Ltd
Priority date: 2020-06-04
Filing date: 2020-06-04
Publication date: 2022-04-13
Anticipated expiration: 2040-06-04
Also published as: GB202008396D0; GB2599614B

Abstract

An active tuned vibration absorber 100 for reducing vibrations in a structure is provided. The active tuned vibration absorber 100 is housed in a housing 200 that has a cap 210 for connecting the active tuned vibration absorber 100 to an electrical power source. The cap 210 comprises one or more electrical power inputs 220 and one or more electrical connectors 230 for coupling the respective one or more electrical power inputs 220 to the active tuned vibration absorber 100. Each of the one or more electrical connectors 230 comprises an elongate pin (310, figure 3a) protruding from a substrate and surrounded by an electrically conducting coiled spring (320, Figure 3a) electrically connected to the elongate pin. The coiled spring has a first portion (340, figure 3a) proximal the substrate having a first uncompressed length and a first radius about a longitudinal axis of the elongate pin, and a second portion (350, Figure 3a) distal the substrate for contacting a respective contact pad coupled to the active tuned vibration absorber 100. The second portion has a second uncompressed length, and a radius that flares radially outwardly along its second uncompressed length from the longitudinal axis of the elongate pin.

Description

Active Tuned Vibration Absorber

FIELD OF THE INVENTION

The present invention relates to an active tuned vibration absorber for reducing vibrations in a structure.

BACKGROUND OF THE INVENTION

Tuned vibration absorbers are devices that can be attached to a structure (including a fixed structure, such as a bridge, or a moveable structure, such as an aircraft) in order to reduce vibrations in the structure. Tuned vibration absorbers can be divided into two types: passive tuned vibration absorbers and active tuned vibration absorbers.

Passive tuned vibration absorbers include a moveable mass, some form of spring and (optionally) a damping element that together form a resonant mechanical system. The vibration absorbers are tuned, by appropriate choice of components, so that they resonate within a predetermined range of frequencies of vibration corresponding (for example) to an expected range of frequencies of vibration in the structure. When the vibration absorber responds strongly to a vibration in the structure, energy is transferred to the vibration absorber and is then dissipated within the vibration absorber. As a consequence, the vibrations in the structure may be reduced.

The Q factor of a resonant system is a measure of the amount of damping in the system (or, equivalently, it is a measure of the 'quality' of resonance). The Q factor is defined in various ways for different types of resonant systems. For example, for a mechanical system the Q factor can be determined by the formula Q = \(MK) / R, where M is the moveable mass of the absorber, K is the spring stiffness, and R is the mechanical resistance (damping), defined as Fdamping = -R.0 (where u = the velocity of the mass, and Fdamping = the force exerted by the damping element on the mass in the direction of the velocity).

More broadly, the mechanical impedance Z of a system at a given angular frequency co can be defined (using complex variables) as Z(fw) = few) / u(/co) where f(/co) is the complex amplitude of the force applied to the system at a frequency co and u(lut) is the complex amplitude of the resulting velocity in the direction of the force.

A system with a low Q factor has a relatively small response when driven at its resonant frequency by an external input On this case, vibrations from the structure to which the vibration absorber is attached) but it also responds over a relatively large range of frequencies. In addition, a system with a low Q factor (high damping) reaches a steady state relatively quickly after a perturbation to the system (such as a change to the amplitude or frequency of external stimulation, for example). By contrast, a system with a high Q factor has a very strong response at its resonant frequency, but the system's response falls off quickly at frequencies moving away from the resonant frequency. A system with a high Q factor also takes longer to settle into a steady state when it is perturbed (it can experience 'ringing', with the system response oscillating for many cycles until reaching a steady state again).

Increasing the Q factor of a vibration absorber increases the response to vibrations, and can allow a smaller mass to be used without reducing the energy absorption at the resonant frequency. This is a significant consideration on structures such as aircraft, for example, where minimising mass is important. However, increasing the Q factor also increases the selectivity of the vibration response, and requires the vibration absorber to be more precisely tuned to the source of vibration. It can also be expensive and technically difficult to achieve very high Q factors (very low internal damping) in passive tuned vibration absorbers.

For some applications, such as noise reduction on aircraft, passive tuned vibration absorbers are generally not suitable. This is because the weight considerations require a vibration absorber to be provided with a high Q factor, and the expected range of frequency of vibrations in the structure exceeds the necessarily narrow bandwidth of response (because of the high Q factor, as noted above). The frequencies of vibration in the structure can also vary with time, and the properties of the passive vibration absorbers can also change over time because of the degradation of components and changes to environmental conditions.

Active tuned vibration absorbers are better suited to such applications. Active tuned vibration absorbers include all of the elements of a passive tuned vibration absorber, but also include an actuator for applying a force between the moveable mass and the structure and a control system for controlling the actuator. The actuator is driven either to impart energy to the mechanical system or to remove it from the system. A typical active tuned vibration absorber detects vibrations affecting the structure using sensors positioned in or adjacent to the vibration absorber, and uses a feedback loop to drive the actuator so as to counteract the detected vibrations. Adaptive filtering can be used to retune the vibration absorber, for example to track changes to the major frequencies of vibration in the structure (such changes arising, for example, due to changes in propeller or turbine speed). The aim of the control system of an active tuned vibration absorber is normally to reduce the detected vibrations to as close to zero as possible.

Such an active tuned vibration absorber suffers some drawbacks, however. The active tuned vibration absorber, unlike the passive variants, requires a power supply, which can be difficult to achieve reliably when the device, but its very nature, is required to create vibrations. Prior art solutions have used a pogo pin arrangement, where an electrical supply is electrically coupled to a controller that supplies the coils used to drive the actuator via pogo pins contacting pads internally to the active tuned vibration absorber. Often these pogo pins are required to carry large currents (hundreds if not thousands of amps) However, it has been found that these arrangements deteriorate over time due to the vibrational forces within the system.

As such, we have appreciated the need for an improved means of providing the required supply to an active tuned vibration absorber.

SUMMARY OF THE INVENTION

The present invention addresses this need with the active tuned vibration absorber according the independent claim appended hereto. Advantageous embodiments are presented in the dependent claims, also appended hereto.

In particular, the present invention provides an active tuned vibration absorber for reducing vibrations in a structure, the vibration absorber comprising: a mount for attachment to the structure; a moveable mass; a spring arrangement connected between the mass and the mount; and an actuator arrangement for applying a force between the mass and the mount; a control system for generating an actuator driving signal for driving the actuator, wherein the active tuned vibration absorber is housed in a housing, and wherein the housing comprises a cap for connecting the active tuned vibration absorber to an electrical power source, the cap comprising: one or more electrical power inputs; and one or more electrical connectors for coupling the respective one or more electrical power inputs to the active tuned vibration absorber, wherein each of the one or more electrical connectors comprises an elongate pin protruding from a substrate and surrounded by an electrically conducting coiled spring electrically connected to the elongate pin, and wherein the coiled spring comprises: a first portion proximal the substrate having a first uncompressed length and a first radius about a longitudinal axis of the elongate pin, and a second portion distal the substrate for contacting a respective contact pad coupled to the active tuned vibration absorber, the second portion having a second uncompressed length a radius that flares radially outwardly along its second uncompressed length from the longitudinal axis of the elongate pin.

Advantageously, the flared radius of the second portion of the spring provides for a much improved contact means for contacting the electrical contact pad to transfer the power supply required to power the coils of the actuator. As the flared portion is brought into contact with the pad, it compresses, but still retains a wide radius, meaning that any vibrational forces will not cause the spring to lose contact with the pad. Furthermore, the flared radius provides a contact portion that has a lower stiffness compared to other portions of the spring (for example the first portion), meaning that not all vibrational components are transferred through the flared portion.

When a respective electrical connector is in contact with a respective contact pad of the active tuned vibration absorber, the coiled spring may be compressed along at least a portion of its length. When the coiled spring is compressed along at least a portion of its length, the second portion may be compressed.

When the second portion is compressed, a plurality of the coils of the spring comprising the second portion concertina such that a plurality of coils may be in contact with the contact pad.

The second portion of the coiled spring may have a lower stiffness than of the first portion of the coiled spring.

The housing and cap may be hermetically sealed.

The active tuned vibration absorber may comprise: a first sensor for providing a first measurement indicative of a force exerted between the structure and the mount; a second sensor for providing a second measurement indicative of an acceleration of the structure at or proximate to the mount; and a control system for generating an actuator driving signal for driving the actuator using the first and second measurement, wherein the control system is operable to generate the actuator driving signal using the first and second measurement to cause the first measurement and second measurement to conform to a target relationship.

The control system may be operable to generate an actuator drive signal to cause the mechanical impedance of the vibration absorber to converge to a target mechanical impedance substantially equivalent to the mechanical impedance of a passive tuned device.

The first sensor may be a force sensor attached to or proximate the mount, or the first sensor may be an accelerometer attached to the moveable mass. The second sensor may be an accelerometer attached to or proximate the mount.

The control system may instead be a feedforward control system for generating an actuator driving signal for driving the actuator arrangement, the actuator driving signal being generated to cause the mechanical impedance of the vibration absorber to converge to a target mechanical impedance substantially equivalent to the mechanical impedance of a passive tuned device.

Alternatively, the active tuned vibration absorber may comprise: a force sensor attached to or proximate the mount for outputting a measurement indicative of a force exerted between the structure and the mount; and wherein the control system may be configured for generating a drive signal for the actuator arrangement using the measurement, the actuator drive signal being generated to cause the mechanical impedance of the vibration absorber to converge to a target mechanical impedance substantially equivalent to the mechanical impedance of a passive tuned device..

LIST OF FIGURES

Figure 1 is a schematic diagram of an active tuned vibration absorber; Figure 2 is a schematic diagram of the active tuned vibration absorber of figure 1 incorporating a schematic representation of the electrical connections to a supply; Figures 3a, 3b and 3c show the coiled spring according to the present invention; and Figure 4 shows the coiled spring arrangement on a cap.

DETAILED DESCRIPTION

In brief, the present invention provides an active tuned vibration absorber for reducing vibrations in a structure. The active tuned vibration absorber is housed in a housing that has a cap for connecting the active tuned vibration absorber to an electrical power source. The cap comprises one or more electrical power inputs and one or more electrical connectors for coupling the respective one or more electrical power inputs to the active tuned vibration absorber. Each of the one or more electrical connectors comprises an elongate pin protruding from a substrate and surrounded by an electrically conducting coiled spring electrically connected to the elongate pin. The coiled spring has a first portion proximal the substrate having a first uncompressed length and a first radius about a longitudinal axis of the elongate pin, and a second portion distal the substrate for contacting a respective contact pad coupled to the active tuned vibration absorber, the second portion having a second uncompressed length, and a radius that flares radially outwardly along its second uncompressed length from the longitudinal axis of the elongate pin.

The structure and overall effect of the active tuned vibration absorber will first be described.

Figure 1 is a schematic diagram of an active tuned vibration absorber.

The active tuned vibration absorber 100 is shown attached to a structure 102, which may be a fixed structure such as a building or a mobile structure such as an aircraft fuselage. The vibration absorber 100 includes a mount 104 for rigid attachment to the structure, a moveable mass 106, a spring 108, a low-impedance actuator 110, a force gauge 112, and accelerometer 114 and a control system 116.

It will be appreciated that Figure 1 shows the elements of the vibration absorber in an essentially conceptual form. The spring 108 may be any suitably elastic material or device, such as a compressed air device, elastomer material, coiled metal spring, magnetic assembly and the like, and may have a form quite different to that shown in Figure 1 (and other figures), for example. The mass 106 may in fact be formed from parts of the spring 108 and/or actuator 110. For example, the actuator 110 may comprise a wire coil wound around a permanent magnet (so that when the coil is energised, a force is actuated on the permanent magnet). In this example the permanent magnet may serve the purpose of the mass 106 as well as forming part of the actuator 110. Other variations of construction are of course possible, and further examples are given later on.

The constructional details of the mount 104 can also be varied, provided that the force gauge 112 and accelerometer 114 are disposed in rigid contact with the structure (so that vibrations and accelerations of the structure 102 in the vicinity of the vibration absorber 100 are transmitted substantially directly to the force gauge 112 and accelerometer 114). Any suitable devices can be used to implement the force gauge 112 and accelerometer 114.

The force gauge 112 and accelerometer 114 output electronic signals which are fed into the control system 116. The control system 116 processes the signals and generates an actuator driving signal, which is transmitted to the actuator 110.

The vibration absorber is also supplied with power and may be connected to a communications bus (depending on the application). The actuator 110 and control system 116 may be powered separately, or the actuator 110 may be powered via the actuator driving signal outputted by the control system 116, for example. The force gauge 112 and/or accelerometer 114 may also be powered or may be purely passive devices, depending on the type of devices that are used for those purposes. The electrical connections will be described in more detail below.

The spring 108 has some degree of internal damping (being a real device) but, as is explained later, a separate damping component may be provided, and the mass 106, spring 108 and/or damping component may actually comprise a plurality of separate components arranged in any suitable series or parallel arrangement.

Figure 2 shows the active tuned vibration absorber of figure 1 incorporating a schematic representation of the electrical connections to a supply.

As mentioned above, the vibration absorber is also supplied with power and may be connected to a communications bus (depending on the application). The actuator 110 and control system 116 may be powered separately, or the actuator 110 may be powered via the actuator driving signal outputted by the control system 116, for example. The force gauge 112 and/or accelerometer 114 may also be powered or may be purely passive devices, depending on the type of devices that are used for those purposes.

A power supply 220 is coupled to the ATVA 100 via the cap 210 of the housing of the ATVA. The supply 220 is coupled to the various components requiring power via couplings 240, 250 (and others, not shown for the sake of simplicity with the drawings).

The coupling between the supply 220 and couplings 240, 250 is made via electrical connectors 230, shown here as a simple box, but the details of which will be described in more detail below.

The purpose of the electrical connectors 230 is to transfer power between the supply 220 and couplings 240, 250, whilst being able to perform this function in a noisy environment i.e. due to the vibrations induced by the ATVA 100 in performing its function as a vibration absorber.

There may be one or more electrical connectors 230 performing this function. Each of the electrical connectors 230 comprises an elongate pin 310 (which is electrically conducting) protruding from a substrate (not shown) and surrounded by an electrically conducting coiled spring 320. This coiled spring 320 is electrically connected to the elongate pin, either via contact with the spring, or via a common connection with the elongate pin 310 on the substrate. The coiled spring 320 comprises a first portion 340 that is proximal to the substrate, and a second portion 350 distal the substrate. The second portion 350 is the portion that contacts a corresponding contact pad (not shown) that is coupled with the devices that require power in the ATVA 100. Contacting the contactor pad with the elongate pin 310 and/or the coiled spring 320 completes the electrical connection to enable power to be transferred.

When in its uncompressed form, the coiled spring 320 has a first uncompressed length and a first radius along the first portion 340 about a longitudinal axis of the elongate pin 310. The second portion 350, as can be seen in the figures, has a second uncompressed length and a radius that flares radially outwardly along its uncompressed length from the longitudinal axis of the elongate pin 310.

As the electrical connector 230 is brought into contact with a contact pad at end 330, the second portion 350 begins to compress first and the coils being to concertina together until the elongate pin comes to rest on the contact pad. In this form, the electrical connector 230 form a connector having a contact area spanning from the pin 310 across the width of the coiled spring 320 at its widest end 330. Such a large area of contact is advantageous when large currents are flowing in an environment where there will be vibrational noise.

Since the spring 320 flares outwardly at the distal end over the second portion 350, the second portion has a lower stiffness than of the first portion 340 of the coiled spring. As such, under vibration, the second portion 350 in contact with the contact pad is less likely to fret or come out of contact with the contact pad under these conditions, since the vibrations do not so easily couple into the spring. Since the first portion 340 of the spring 320 has a narrower diameter over its length compared to the second portion 350, the first portion has a higher stiffness, and keeps the second portion 350 in contact with the contact pad when compressed.

Figure 4 shows one possible arrangement of the electrical connectors on a cap that is attached to a ATVA 100.

A more detailed description of the composition and function of the ATVA shown in figure 1 may be found in our prior patents GB2447231 and GB2480785, both of which are incorporated herein by reference. Further embodiments and variants may also be found in the above-mentioned prior patents. As such, the embodiments shown in Figures 1 to 178, and their associated passages in the description of GB2447231 and GB2480785, are incorporated herein by reference. The present invention is intended to work within such ATVAs as described therein, as each require power to be supplied, and the present invention advantageously addresses the problem associated with the prior solutions where the prior connectors could become fatigued or damaged due to the inherently noisy environment in an ATVA.

No doubt many other effective alternatives will occur to the skilled person. It will be understood that the invention is not limited to the described embodiments and encompasses modifications apparent to those skilled in the art lying within the scope of the claims appended hereto.

Claims

CLAIMS: 1. An active tuned vibration absorber for reducing vibrations in a structure, the vibration absorber comprising: a mount for attachment to the structure; a moveable mass; a spring arrangement connected between the mass and the mount; and an actuator arrangement for applying a force between the mass and the mount; a control system for generating an actuator driving signal for driving the actuator, wherein the active tuned vibration absorber is housed in a housing, and wherein the housing comprises a cap for connecting the active tuned vibration absorber to an electrical power source, the cap comprising: one or more electrical power inputs; and one or more electrical connectors for coupling the respective one or more electrical power inputs to the active tuned vibration absorber, wherein each of the one or more electrical connectors comprises an elongate pin protruding from a substrate and surrounded by an electrically conducting coiled spring electrically connected to the elongate pin, and wherein the coiled spring comprises: a first portion proximal the substrate having a first uncompressed length and a first radius about a longitudinal axis of the elongate pin, and a second portion distal the substrate for contacting a respective contact pad coupled to the active tuned vibration absorber, the second portion having a second uncompressed length a radius that flares radially outwardly along its second uncompressed length from the longitudinal axis of the elongate pin.
2. An active tuned vibration absorber according to claim 1, wherein, when a respective electrical connector is in contact with a respective contact pad of the active tuned vibration absorber, the coiled spring is compressed along at least a portion of its length.
3. An active tuned vibration absorber according to claim 2, wherein, when the coiled spring is compressed along at least a portion of its length, the second portion is compressed.
4. An active tuned vibration absorber according to claim 3, wherein when the second portion is compressed, a plurality of the coils of the spring comprising the second portion concertina such that a plurality of coils are in contact with the contact pad.
5. An active tuned vibration absorber according to any preceding claim, wherein the second portion of the coiled spring has a lower stiffness than of the first portion of the coiled spring.
6. An active tuned vibration absorber according to any preceding claim, wherein the housing and cap are hermetically sealed.
7. An active tuned vibration absorber according to any preceding claim, comprising: a first sensor for providing a first measurement indicative of a force exerted between the structure and the mount; a second sensor for providing a second measurement indicative of an acceleration of the structure at or proximate to the mount; and a control system for generating an actuator driving signal for driving the actuator using the first and second measurement, wherein the control system is operable to generate the actuator driving signal using the first and second measurement to cause the first measurement and second measurement to conform to a target relationship.
8. A vibration absorber according to claim 7, wherein the control system is operable to generate an actuator drive signal to cause the mechanical impedance of the vibration absorber to converge to a target mechanical impedance substantially equivalent to the mechanical impedance of a passive tuned device.
9. A vibration absorber according to claim 7 or 8, wherein the first sensor is a force sensor attached to or proximate the mount, or the first sensor is an accelerometer attached to the moveable mass.
10. A vibration absorber according to claim 7, 8 or 9, wherein the second sensor is an accelerometer attached to or proximate the mount.
11. An active tuned vibration absorber according to any one of claims 1 to 6, wherein the control system is a feedforward control system for generating an actuator driving signal for driving the actuator arrangement, the actuator driving signal being generated to cause the mechanical impedance of the vibration absorber to converge to a target mechanical impedance substantially equivalent to the mechanical impedance of a passive tuned device.
12. An active tuned vibration absorber according to claims 1 to 6, comprising: a force sensor attached to or proximate the mount for outputting a measurement indicative of a force exerted between the structure and the mount; wherein the control system is configured for generating a drive signal for the actuator arrangement using the measurement, the actuator drive signal being generated to cause the mechanical impedance of the vibration absorber to converge to a target mechanical impedance substantially equivalent to the mechanical impedance of a passive tuned device.