NZ619612B2 - Passive damper - Google Patents
Passive damper Download PDFInfo
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- NZ619612B2 NZ619612B2 NZ619612A NZ61961212A NZ619612B2 NZ 619612 B2 NZ619612 B2 NZ 619612B2 NZ 619612 A NZ619612 A NZ 619612A NZ 61961212 A NZ61961212 A NZ 61961212A NZ 619612 B2 NZ619612 B2 NZ 619612B2
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Abstract
passive damper 1 for dampening relative movement between members 2,3 of a structure to which the damper 1 can be connected, comprises a first set of parallel disposed plates 17, and a second set of parallel disposed plates 18. The first set of plates and the second set of plates overlap one another in an alternating fashion at a rotational joint with damping pads 25 between the plates 17, 18. The rotational joint comprises a pin or bolt 19 inserted through apertures 24 in the plates 17, 18. The apertures 24a in selected plates 18 are shaped and dimensioned to provide a predetermined amount of clearance with the pin or bolt 19 so that the pin or bolt 19 can move inside the aperture 24a to a predetermined extent without the selected plates 18 taking part in the damping action. r in an alternating fashion at a rotational joint with damping pads 25 between the plates 17, 18. The rotational joint comprises a pin or bolt 19 inserted through apertures 24 in the plates 17, 18. The apertures 24a in selected plates 18 are shaped and dimensioned to provide a predetermined amount of clearance with the pin or bolt 19 so that the pin or bolt 19 can move inside the aperture 24a to a predetermined extent without the selected plates 18 taking part in the damping action.
Description
PASSIVE DAMPER
The present invention relates to a damper that can be used to
protect a structure or a structural system, e.g. a building
against dynamic stress such as the stress caused by an
earthquake, the shock of a large sea wave, or a stress that
is produced by vibration and the like caused by shocks from
transportation, machines, wind, or the like. More
specifically, the invention relates to a damper that can
operate with different damping forces for different
displacement magnitudes.
BACKGROUND OF THE INVENTION
When a structure or structural system is excited, elements of
the structure may get displaced relative to one another. If
such displacements are large, or if they occur periodically,
they may have serious impact on the conditions of the
structure, and may cause severe damages or even result in a
collapse.
Dampers play an important role in the protection of
structures such as buildings, and they exist in numerous
variants. Dampers are typically damping the motion by means
of a friction force between two parts attached to the frame
structure of the building, or by means of a fluid being
pressed to flow between two chambers through a restriction.
Other similar well-known methods of damping motion or
vibrations exist. Some dampers are actively changing the
damping effect corresponding to external conditions, and
other dampers are passive dampers having a constant damping
characteristic. The active dampers are expensive and
technically complicated devices, which need extensive
maintenance in order to work when needed. Further, they are
prone to malfunctions, e.g. leaking of hydraulic fluids or
breakdown of electronic control systems.
WO 2011038742 discloses a passive damper that is constructed
with overlapping sets of plates connected by a bolt with
damping pads arranged between the plates and the bolts
applying a compression force on the plates and the damping
pads therebetween. The damper impedance can be adjusted by
changing the compression force. However, this can only be
done during installation or during service, and not in
response to an event such as a seismic event.
Passive dampers with a variable damping characteristics are
sometimes desirable but no commercially viable dampers of
such kind are presently available.
DISCLOSURE OF THE INVENTION
On this background, it is an object of the present
application to provide a passive damper for dampening
relative movement between members of a structure to which the
damper can be connected that has a damper characteristic or
impedance that changes with the amplitude of the oscillations
or with magnitude of the movement that it is exposed to.
Alternatively, it is an object of the invention to at least
provide the public with a useful choice.
Any of these objects are achieved by providing a passive
damper for dampening relative movement between members of a
structure to which the damper can be connected, the damper
includes at least a first set of parallel disposed plates,
and a second set of parallel disposed plates, the first set
of plates and the second set of plates overlap one another in
an alternating fashion at a rotational joint with damping
pads between the plates, the rotational joint comprises a pin
bolt inserted through apertures in the plates, a connection
hole in each of the plates of the second set of plates for
receiving a connection pin therein for connecting the second
set of plates to one of the members, the connection holes in
a selection of the plates of the second set of plates are
shaped and dimensioned to provide a predetermined amount of
clearance with the connection pin so that the connection pin
can move inside the connection holes of the selection of the
plates to a predetermined extent without the selection of
plates taking part in the damping action of the damper.
By providing a predetermined amount of clearance between the
apertures of selected plates and the connection pin it is
possible to construct a damper in which only a few of the
plates become active in the damping process when the
oscillations or movements have a relatively small magnitude,
whilst more of the plates come into action when the magnitude
of the oscillations or movements increases and becomes of a
relatively larger magnitude. Thus, it becomes possible to
have a damper that provides for relatively little damping
forces at small magnitudes of oscillations or movements and
that provides a progressively increased damping force
(impedance) when the oscillations or movements become a
larger and are of a substantial magnitude. This means that
the damper impedance has a value that changes stepwise in
relation to the size or magnitude of the movement of the
damper .
Preferably, the shape and size of the connection holes in the
plates outside the selection being dimensioned relative to
the shape and size of the cross-section of the connection pin
such that the plates in the second set of plates outside the
selection have substantially no clearance between their
respective connection hole and the connection pin.
The shape and size of the connection holes in the plates of
the selection may be dimensioned relative to the shape and
size of the cross-section of the connection pin such that
plates in the selection of plates of plates have a first
amount of substantial amount of clearance between their
respective connection holes and the connection pin.
In an embodiment the plates outside the section selection of
plates move with the one member at any amplitude of movement
of the one member and wherein the plates in the selection
move with the one member only if the extent of the movement
of the one member exceeds the clearance between the
connection hole concerned and the connection pin.
Preferably, the connection holes of the selection of plates
have an elongated outline or shape.
In an embodiment the damper includes a further selection of
plates within the selection of plates the shape and size of
the connection holes of the further selection of plates
relative to the shape and size of the cross section of the
connection pin being such that the extent of clearance
between the connection holes concerned and the connection pin
is larger than the first substantial amount of clearance.
In another embodiment the plurality of damper pads comprises
first selection of pads with a first effective contact area
size and a second selection of pads with a second effective
contact area size different from the first contact area size.
In yet another embodiment the damper pads are disk shaped
with a central hole and the effective contact area is
differentiated in a selection of damping pads through the
section of the outer diameter and/or the inner diameter of
the damping pads concerned.
The objects above may also be achieved by providing a passive
damper for dampening relative movement between members of a
structure to which the damper can be connected, the damper
including a first set of parallel disposed plates, and a
second set of parallel disposed plates, the first set of
plates and the second set of plates overlap one another in an
alternating fashion at a rotational joint with damping pads
between the plates the rotational joint comprises a pin or
bolt inserted through apertures in the plates, whereby
apertures in a selection of the plates are shaped and
dimensioned to provide a predetermined amount of clearance
with the pin or bolt so that the pin or bolt can move inside
the aperture to a predetermined extent without the selection
of plates taking part in the damping action.
Further objects, features, advantages and properties of the
damper according to the present disclosure will become
apparent from the detailed description.
Unless the context clearly requires otherwise, throughout the
description and claims the terms “comprise”, “comprising” and
the like are to be construed in an inclusive sense, as
opposed to an exclusive or exhaustive sense. That is, in the
sense of “including, but not limited to”.
BRIEF DESCRIPTION OF THE DRAWINGS
In the following detailed portion of the present description,
the invention will be explained in more detail with reference
to the exemplary embodiments shown in the drawings, in which:
- Figs. 1a-1d are a various views of an exemplary
embodiment of a damper connected to two members of a
structure,
- Fig. 2a is a side view of an exemplary embodiment of a
damper,
- Figs. 2b-2d show different plates used in the damper
shown in Fig. 2a,
- Figs. 3a-3d is a series of side views of the damper
shown in Fig. 2a with an increasing extent of movement,
- Figs. 4a-4d is a series of rear views of the damper
shown in Fig. 2a in an increasing extent of movement,
- Fig. 5 is a rear view of the damper according to Fig. 2
illustrating exemplary damping pads used therein,
- Fig. 6 is a side view of another embodiment of a damper,
- Fig. 7 is a top of the damper according to Fig. 6, and
- Figs 8 and 9 show different plates used in the damper
shown in Fig. 6
- Fig. 10a, in a side view, shows another embodiment of a
damper according to the invention,
- Fig 10b, in a top view, shows the damper according to
Fig. 10a,
- Fig. 10c shows how each of the damper's second elongate
plates may be differently configured from each other,
- Fig. lOd shows one configuration of a first plate in the
damper according to Figs. 10 and 10b,
- Fig. lOe shows another configuration of a first plate in
the damper according to Figs. 10 and 10b, and
- Fig. lOf shows yet another configuration of a first
plate in the damper according to Figs. 10 and 10b.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Below follows a description of embodiments of the present
invention, referring to the figures. In the below
description, a member of a structure, such as a building, is
understood to include e.g. pillars, beams, stiffeners,
stretchers, v-braces and the like, and any member which
maintains the rigidity of a structure of a construction or
structural body of e.g. a building or the like.
With reference to Figs la to Id a damper 1 according to an
exemplary embodiment is shown connected to members 2, 3 of a
structure, such as a building. The damper 1, in this
embodiment is substantially T-shaped. Each end of the T-
shaped damper is connected to the structure. The two opposite
ends to the "top" or horizontal line of the T are connected
via respective pins 6 and brackets 5 to member 3 of the
structure. The free end of the "leg" or vertical line of the
T is connected via a pin 6 and a bracket 4 to member 2 of the
structure .
With reference to Figs 2a-2d, 3a - 3d and 4a-4d the damper 1
according to an exemplary embodiment is illustrated in
greater detail.
The passive damper 1 includes a first set of plates 7 forming
the "top" of the T . The first set of plates 7 includes a
plurality of elongate plates 7a that are substantially
identical in shape and size. In the shown embodiment the set
of plates 7 includes six plates 7a that are disposed in
parallel, i.e. extending in the same direction and at the
same distance apart at every point. In other embodiments the
first set of plates 7 can include as few as three plates 7a
or many more than six plates 7a arranged in parallel. The
plates 7a have a rectangular cross-section and an outline
like a stadium, i.e. the end section or at least the corners
are preferably rounded.
The passive damper 1 includes a second set of plates 8
forming the "leg" or the vertical or upright line of the T .
The second set of plates 8 includes a plurality of elongate
plates 8b, 8c, 8d that are substantially identical in shape and
size. In the shown embodiment the set of plates 8 includes
five plates 8b, 8c, 8d that are disposed in parallel, i.e.
extending in the same direction and at the same distance
apart at every point. In other embodiments the second set of
plates 8 can include as few as two plates 8a or many more
than five plates 8a arranged in parallel. The plates 8a have
a rectangular cross-section and an outline like a stadium,
i.e. as describe for the first set of plates 7 above.
The first set 7 of plates and said second set 8 of plates
overlap one another in an alternating fashion at a rotational
joint that is placed substantially in the middle of the
longitudinal extent of the plates 7a of the first set of
plates 7 and at one (non-free) longitudinal extremity of the
plates 8b, 8c, 8d of the second set of plates 8 . The rotational
joint allows the plates 7a, 8b, 8c, 8d to rotate with respect
to each other.
Damping pads 15a are arranged between the plates 7a, 8b, 8c, 8d
at the rotational joint.
The plates of the first 7 set and of the second set 8 are
arranged such that a plate 7a, 8b, 8c, 8d of one of the sets 7,8
is inserted between two plates 7a, 8b, 8c, 8d of the other set
7,8 with damping pads 15a sandwiched between neighboring
plates 7a, 8b, 8c, 8d, except for two outer plates 7a that
belong to the first set of plates 7.
The damping disks or pads 15a may be made from a friction
material or from a visco-elastic material. The damping disks
15a are provided for damping movements between the first set
7 of elongate plates 7a, in relation to the second set 8 of
elongate plates 8b,8c,8d. When friction material is used for
the damping disk 15a, relative rotational movement between
plates 7a, 8b, 8c, 8d, is dampened/attenuated by fiction and the
forces related thereto.
Preferably, compound materials are used for the friction
material, selected from materials such as brass and aluminum,
or, alloys thereof, or compound fiber materials such as
plastic and glass, carbon and the like, or, optionally
compound fiber materials such as ceramic materials and glass,
carbon, and the like.
Suitable visco-elastic materials for the damping disks 15a,
are for example, rubber, acryl polymers, copolymers,
optionally glass-like materials and the like and combinations
thereof, which disperses energy when exposed to shear
deformation .
The damping pad or disk 15a may be a of disc shape and with
an opening, hole or aperture, to correspond to the respective
holes or apertures in the first elongate plates 7a and in the
second elongate members 8b, 8c, 8d, respectively.
The rotational joint includes a pin or bolt 9 inserted
through apertures 15 in each of the plates 7a, 8b, 8c, 8d of
both sets of plates 7,8 and the pin or bolt 9 joins the
plates 7a, 8b, 8c, 8d together, with a nut 9a affixed to the
threaded free end of the bolt 9 . The apertures or holes in
the plates 7a and 8a, 8b, 8c have a circular outline. The
diameter of the apertures or holes is slightly larger than
the diameter of the pin or bolt 9 so that the plates 8b, 8c, 8d
can rotate about the pin or bolt without any excess backlash
or play.
A clamping member, e.g. in the form of a disc spring 11 and
washers 12, may further be attached via the bolt 9 and nut
9a. There are washers 10 provided on the outwardly facing
surface of the elongate plates 7a that is located in outer
layer of the first set 7 of plates 7a. There are clamping
means in the form of disc springs 11 arranged on the outer
surface of each of these washers 10. The clamping means/disc
springs 11 functions as an energy buffer for the compression
or clamping force, pressing the plates 7a and the plates
8b, 8c, 8d together and towards the damping pads or disks 15a.
There may be provided holes or apertures in the damping discs
15a for receiving the pin or bolt 9 therein. There may be
washers 12 arranged on the opposite side of the disc springs
11 with respect to the washers 10. The bolt 19 is passed
through the washers 12, the holes in the disk springs 11, the
holes in the plates 7a, 8b, 8c, 8d and the nuts 9a is affixed to
the extremity of the bolt 9 where the bolt protrudes from the
holes. To prevent loosening, a double nut (not shown) may be
used .
The compression or clamping force that presses the plates 7a
and the plates 8b, 8c, 8d onto the damping disks 15a can be
adjusted using the amount of tightening on the nut 9a, the
spring constant of the disc springs 11, or the number of
layers of disc springs 11.
A rotational joint is provided near the two opposite
longitudinal extremities of the plates 7a of the first set 7 .
This joint may be in the form of a circular hole or aperture
13 in each of the plates 7a of the first set 7 . The hole or
apertures 13 are adapted for connection to a member 3 of the
structure via a bracket 5, by a connection pin 6 as shown in
Figs, la to Id with the holes or apertures having a diameter
slightly larger than the diameter of the hinge connection pin
6 to allow rotation of the plates 7a relative to the
connection pin 6 with a minimal amount of play or backlash.
A rotational joint is also provided near the longitudinal
extremities of the plates 8b, 8c, 8d of the second set 8 . This
joint may be in the form of a circular connection hole or
aperture 14b in the plates 8b with a diameter relative to the
diameter of the connection pin 6 that provides for a small
amount of clearance or backlash that allows the plates to
rotate relative to the connection pin 6 . The joint can also
be in the form of an enlarged circular hole (not shown)
and/or in the form of an elongate connection hole 14c, 14d
with a stadium like outline in the plates 8c, 8d. Various
shapes for the outline of the connection hole 14c, 14d can be
used as long as the shape and size of the connection hole
14c, 14d relative to the shape and size of the (cross-section
of the) connection pin 6 provides for the desired amount of
clearance in the desired direction or directions. For a
connection pin 6 with a circular cross-section connection
holes with a circular, oval elliptic, stadium like or other
rounded outline is suitable. For some applications only a
particular direction for the clearance will be required
whilst other applications may require clearance in another
direction or in several directions.
In the shown exemplary embodiment the connection holes
14c, 14d are provided with a predetermined amount of clearance
relative to the diameter of the connection pin 6 for allowing
a predetermined magnitude of movement in a given direction of
the connection 6 relative to the plate 8c, 8d concerned
without the plate 8c, 8d concerned moving with the connection
pin 6 . The amount of clearance of the holes 14c in the plates
8c is of a first substantial amount and the amount of
clearance of the connection holes 14d in the plates 8d is of
a second substantial amount of clearance that is larger than
the first amount of clearance. The connection holes or
apertures 14b, 14c, 14d are adapted for connection to a member
2 of the structure via a bracket 4, by a connection pin 6 as
shown in Figs la to Id.
A selection of said plates 8c, 8d of said first set of plates
8c, 8d has connection holes 14c, 14d that are shaped and
dimensioned to provide a predetermined amount of clearance
with said connection pin 6 so that said connection pin 6 can
move inside the connection holes 14c, 14d of said selection of
said plates 8c, 8d to a predetermined extent without said
selection of plates 8c, 8d taking part in the damping action
of the damper 1 . This effect is illustrated in the series of
Figs. 3a to 3d and 4a to 4d. The upwardly pointing arrow
illustrates movement of the connection pin 6 . As shown in
these Figs. 3b and 4b, the plates 8b with the holes 14b with
the minimum amount of clearance with respect to the
connection pin 6 move with the connection pin 6 at the first
movement of the connection pin. The plates 8c, 8d in the
selection do not move. The damping effect (impedance) of the
damper is at this extent of movement of the connection pin 6
only determined by the plates 8b.
As shown in Figs 3c and 4c, the plates 8b with the holes 14b
with the minimum amount of clearance with respect to the
connection pin 6 and the plates 8c with the connection holes
14c with a first substantial amount of clearance with respect
to the connection pin 6 all move when the extent of the
movement of the connection pin 6 exceeds a predetermined
level (the extent of the movement of the connection pin 6 in
Figs 3c and 4c is larger than in Figs. 3b and 4b) . The plates
8d still do not move. The damping effect (impedance) of the
damper 1 is at this extent of movement of the connection pin
6 determined by the plates 8b and 8c.
As shown in these Figs 3d and 4d, with even larger extent of
movement of the connection pin 6 the plates 8b with the holes
14b with the minimum amount of clearance with respect to the
connection pin 6 and the plates 8c with the connection holes
14c with a first substantial amount of clearance with respect
to the connection pin 6 and the plates 8d with the connection
holes 14d with a second substantial amount of clearance with
respect to the connection pin 6 all move when the extent of
the movement of the connection pin 6 exceeds a further
predetermined level. The damping effect (impedance) of the
damper 1 is at this extent of movement of the connection pin
6 determined by all the plates 8b, 8c and 8d in the second
set .
For the material of the plates 7a, 8b, 8c, 8d, metals, like
steel, resins, ceramics, carbon fibers, combinations thereof
and the like may be used.
It is noted that the construction of the damper 1 and in
particular the connection means to the member 2,3 of the
structure can be reversed. In this reversed construction the
plates 8 are provided with pins (not shown) and the structure
2,3 or a bracket 4,5 rigidly connected to the structure 2,3
is provided with apertures with a shape and size that
provides the required amount of clearance with the respective
pins of the plates.
Figure 5 shows another exemplary embodiment. This embodiment
is essentially identical to the embodiment described here
above, except for some modifications to the damping disks.
The dimensions of the individual damping pads or discs 25 in
a set of friction pads or discs 25 that is associated with
the rotational particular joint between the first set of
plates 7 and the second set of plates 8 can be selected in
order to obtain particular characteristics for the damper 1 .
Thus, there can be first damping discs with e.g. a larger
inner diameter in a set of damping discs whilst the other
second damping discs of the set damping discs have a smaller
inner diameter. Therefore, the first damping discs have a
smaller effective surface area compared to the second damping
discs. The damping effect between plates 7a, 8b, 8c, 8d with
the first damping discs therebetween will be less than the
damping effect between elongate plates 7a, 8b, 8c, 8d with the
second damping discs therebetween. Consequently, by having a
set of damping discs or pads that includes individual damping
discs or pads with different dimensions the characteristics
of the damper can be adapted to the needs. In the exemplary
embodiment shown in figure 5 three different types of damping
discs 15a, 15b, 15c with varying dimensions and effective
contact surface area have been used.
Fig. 6 shows a side view of a damper 1 according to another
exemplary embodiment for damping movements/oscillations in a
construction for a system according to one embodiment of the
present invention. Fig. 7 shows a top view of the same
damper .
The damper 1 includes two sets of first elongate plates 17;
two sets of second elongate plates 18; and damping pads or
disks 25 sandwiched between the two sets of the first
elongate plates 17 and the two sets of second elongate plates
18. The set of second elongate plates 18 are connected to the
two sets of the first elongate plates 17, such that they may
rotate with respect to each other, in rotational connections.
The first elongate plates 17 are formed from stadium shaped
plates, i.e. the end sections or at least the corners of the
plates are preferably rounded. A rotational joint 23 is
provided near one extremity 17a of the plates 17. The joint
23, may as shown be in the form of a circular hole or
aperture in each of the plates of the set is adapted for
connection to a structural member, by a connection pin
similar as described with reference to the embodiments
described here above.
In the shown embodiment, the rotational connections are
formed by holes or openings in the first elongate plates 17,
and in the second elongate members 18, and each of the
rotational connections are formed in series along the
longitudinal axis of the first elongate plates 17. Further
the rotational connections may be provided as shown by a bolt
19 which extends through the respective elongate plates 17,
18 and joins them together, with a nut 19a affixed to the
threaded free end of the bolt 19.
A clamping member in the form of e.g. a disc spring 21, and
washers 22 may further be attached via the bolt 19 and nut
19a. The two sets of first elongate plates 17 are arranged
in parallel. The joints 23 of the one set of first elongate
plates 17 are arranged adjacent to the opposite end 17a of
the other set of first elongate plates 17.
The two sets of second elongate plates 18 are arranged so as
to be parallel to one another. These two sets of second
elongate plates 18 are also plate members with an outline
like a stadium, with holes or apertures 14, that form part of
the rotational connections, together with the holes or
apertures 23 in the first elongate plates 17.
For the first and second elongate plates 17,18, the same
materials metals, can be used as for the plates of the
embodiment described above.
A damping disk or pad 25 is provided between each first
elongate plate 17 and second elongate plate 18. Thus, there
is a set of damping discs or pads 25 associated with each
rotational joint.
The damping disks or pads 25 may be made from the same
friction or visco-elastic material as described for the
embodiment above .
As shown in figure 7 the damping pad or disk may be a of disc
shape and with an opening, hole or aperture 26, to correspond
to the respective holes 23, 24 in the first elongate plate 17
and in the second elongate plate 18, respectively.
Similar to the embodiments described above with reference to
figures 1 to 5, the dimensions of the individual damping pads
or discs 25 in a set of friction pads or discs 25 that is
associated with a particular joint can be selected in order
to obtain particular characteristics for the damper. Thus,
there can be first damping discs with e.g. a larger inner
diameter in a set of damping discs whilst the other second
damping discs of the set damping discs have a smaller inner
diameter. Therefore, the first damping discs have a smaller
effective surface area compared to the second damping discs.
The damping effect between elongate plates 17, 18 with the
first damping discs therebetween will be less than the
damping effect between elongate plates 17, 18 with the second
damping discs therebetween. Consequently, by having a set of
damping discs or pads that includes individual damping discs
or pads with different dimensions the characteristics of the
damper can be adapted to the needs .
In the damper 1, shown in Fig. 6 and 7, there are eight first
elongate plates 17 (four in each set) , ten second elongate
plates 18 (five in each set), and 16 damping disks or pads
There are washers 20 located on the surface of the second
elongate plates 18 that are located in the uppermost layer
and on the surface of the second elongate plates 20 that are
located in the lowermost layer, respectively. There are
clamping means in the form of disc springs 21 arranged on the
outer surface of each of these washers 20. The clamping
means/disc springs 21 functions as an energy buffer for the
compression or clamping force, pressing the first elongate
plates 17 and the second elongate plates 18 together and
towards the damping members 25. There may be provided holes
or apertures in the disc springs 21 that also correspond to
the holes 23, 24, and 26 to provide the abovementioned
rotational connection. There may be washers 22 arranged on
the opposite side of the disc springs 21 with respect to the
washers 20. The bolts 19 are passed through the washers 22,
the holes in the disk springs 21, the holes 23,24 and 26, and
the nuts 19a are affixed to the tips of the bolts 19 where
they protrude from the holes. The nut 19a is to prevent
loosening, so a double nut is used.
The compression or clamping force that first elongate plate
17 and the second elongate plate 18 press on the friction
member 25 can be adjusted using the amount of tightening on
the nuts 42, the spring constant of the disc springs 21, or
the number of layers of disc springs 21.
The shape and dimension of the holes or apertures 24 in the
individual second plates 18 in a set can be chosen relative
to the shape and dimension of the bolt 19 to provide a larger
or smaller amount of clearance between the bolt 19 and the
hole or aperture 24. This is illustrated in Fig. 8 and Fig.
Fig. 8 shows a "regular" second elongate plate 18. The
elongate plate 18 is provided with a circular hole or
aperture 24 near each of its two opposite ends. The diameter
of the circular hole or aperture 24 is chosen relative to the
diameter of the bolt 19 such that there is a small or minimal
amount of clearance between the hole or aperture 24 and the
bolt 19 for allowing rotational movement of the bolt 19
relative to the second elongate plate 18, though without
providing a substantial clearance or backlash between the
bolt 19 and the second elongate plate 18. Thus, when the bolt
19 moves, e.g. due to e.g. a movement of the set of first
elongate plates 17 this type of second elongate plate 18 will
move substantially in unison with the bolt, also for
relatively small movements of the bolt 19.
Fig. 9 shows a "special" second elongate plate 18. The
special elongate plate 18 is provided with an elongate hole
or aperture 24a near one of its two opposite ends and with a
conventional circular hole or aperture 24 near its opposite
end. The diameter of the circular hole or aperture 24 is
chosen relative to the diameter of the bolt 19 is as
described for the regular second elongate plate.
The dimension of the elongate hole or aperture 24a is chosen
relative to the diameter of the bolt 19 such that there is a
substantial amount of clearance between the hole or aperture
24 and the bolt 19 for allowing translational movement in at
least on direction of the bolt 19 relative to the second
elongate plate 18. Thus, when the bolt 19 moves in the
direction of the longitudinal extent of the elongate hole or
aperture 24a, e.g. due to e.g. a movement of the set of first
elongate plates 17 this type of second elongate plate 18 will
not move in unison with the bolt, when the movement of the
bolt 19 is smaller than the longitudinal extent of the
elongate hole or aperture 24a. The bolt 19 will urge or force
the second elongate plate 18 to move only when the extent of
the movement of the bolt 19 in the direction of the
longitudinal extent of the elongate hole or aperture 24a is
larger than the longitudinal extent of the elongate hole or
aperture 24a. Thus, by choosing the shape and dimensions of
the hole or aperture 24 in the second elongate plate 18 it
can be decided at which extent of size of movement or at
which of amplitude of an oscillation at particular second
elongate plate 18 will start moving and starts to provide a
damping effect. This renders it possible to design a damper
1 with one or more sets of second elongate plates 18 that
includes one or more elongate plates 18 with the special
apertures 24 that provide for a substantial amount of
clearance between the bolt 19 and the second elongate plate
18 concerned. This allows for the construction of a damper 1
for which certain second elongate plate 18 come into action
immediately, i.e. at small movements only the regular plates
18 come in action whilst the other "special" elongate plates
18 of the set concerned will only come into action at the
larger movements of the bolt 19, i.e. when the movements are
caused by vibrations with a greater amplitude. The provision
to include different types of second elongate plates 18 opens
the possibility to design the damping characteristic
(impedance) according to the particular needs of the
construction in which the damper 1 is to be used.
The operation of the dampers 1 according to the present
exemplary embodiment is known in detail from the prior art
document cited in the introductory portion of the present
description. Shortly explained, when a force substantially in
the direction of the longitudinal extent of the first
elongate plates 17 is applied to the joints 23 of the
respective elongate plate 17 in opposite directions in the
damper 1 either extends or retracts which causes a relative
rotational movement between the first elongate plate 17 and
the second elongate plate 18 about the joints defined by the
bolts 19 and the relative rotational movement causes energy
to be dissipated between the respective elongate plate 17, 18
and the damper pads or discs 25 therebetween. The energy
dissipation causes the damping effect. Depending on the
amplitude or size of the movement only a few of the elongate
plates 18 or all of the elongate plates 18 move and
participate in the damping effect.
Figs. lOa-lOf shows a damper 1 similar to the one shown in
Figs 6-9. The same reference numbers are used for like parts.
The damper 1 in this embodiment have 6 first plates 17 and 12
second plates 18, but embodiments with more plates may be
made. For the clarity of this description, the first plates
17 shown in the top of Fig 10a are called upper plates and
designated by the reference number 17'. Similarly the first
plates 17 shown in the bottom of Fig 10a are called lowe
plates and designated by the reference number 17''. In the
real damper the orientation may be different.
In Fig. 10c two different second plates are shown. The plate
on the left of the figure has holes 24 adapted with a
clearance to match the dimensions of the bolt 19. The plate
to the right in the figure has holes 24b with a larger
dimension. The dimension of the holes in the plate to the
right in the figure can be compared to the dimension of the
holes 24 in the plate on the left of the figure by the size
of the smaller holes being indicated by a dashed line. With
arrows the location of the two types of plates in the damper
is shown in the top view of the drawing, Fig. 10b.
In Fig. lOd an upper plate 17' of the first plates 17 is
shown. The hole 23b on the left side of this figure is
adapted for rotational connection to braces (not shown) to
connect the damper to a structural part of a building. The
plate 17' also has two holes 23a adapted for connecting to
the other the other parts (other first and second plates,
friction pads, etc) of the damper 1 via bolt 19. The location
of this first plate 11' is indicated by an arrow to fig. 10b.
It can be seen that the plate is the central one of the three
upper plates 17'.
In fig. lOe another first plate 17 is shown. This can be used
as upper plate 17' or as lower plate 17'' . This plate also
has one hole 23b shown on the left side of the figure, which
is adapted for rotational connection to braces (not shown) to
connect the damper to a structural part of a building. The
plate also has two holes 23a adapted for connecting to the
other the other parts (other first and second plates,
friction pads, etc) of the damper 1 via bolt 19. The plate in
Fig. lOe differs from the plate in Fig. lOd in that the holes
23a in Fig.lOe are dimensioned to adapted with just a minute
clearance to match the dimensions of the bolt 19, whereas the
holes 23a in Fig. lOd are larger than in Fig. lOe. This is
indicated in Fig. lOd by the dashed lines. The dashed lines
show the size of the corresponding holes in Fig. lOe. The
size of these holes 23a in Fig. lOe is the same as the holes
24 in the second plate on the left of Fig. 10c.
The plates in figures lOd and lOe also differs in that the
hole 23b for connection to braces is bigger in the Fig. lOd
plate than in the Fig. lOe plate. Again, the difference in
size is indicated by the dashed line in Fig. lOd. Arrows to
Fig. 10b shows the location of the 4 plates of the Fig. lOe
type .
A third type of first plates 17 is shown in Fig. lOf. This is
for use as a lower plate 17' '. This plate has a hole 23b for
connection to braces of the same size as the plate shown in
fig. lOe, and holes 23a that are larger than the similar
holes in Fig. lOe, as indicated by the dashed lines. An arrow
to Fig. 10b shows the location of the one plate of the Fig.
lOf type.
Thus the damper shown in Figs. 10a and 10b has 3 upper first
plates 17', the central one of which is of the Fig. 10c type,
and the two other of the Fig. lOe type. Further, the damper
shown in Figs. 10a and 10b has 3 lower first plates 17'', the
central one of which is of the Fig. lOf type, and the two
other of the Fig. lOe type. Thereby, the damper may be
adapted for dissipating movements of different magnitudes in
a building in which is installed, in a manner similar to the
embodiments described above.
The embodiment of the damper as described in Figs. lOa-lOf
may further be provided with a set of pads 50 configured for
reducing friction. Such pads 50 may be formed in e.g. Teflon
or another similar material. They may also be constructed
with a ball type bearing. The pads 50 are arranged in the
layers of first and second plates 17, 18 to allow a further
play of those plates having enlarged holes 23a, 23b, 24, see
above .
In Fig 10b the damper 1 may thus be constructed by the
following layering of plates 17, 18, seen from top to bottom
in the figure (for each of the bolts 19) : After the bolts,
the disk spring and the washer, there is arranged a second
plate of the type in the left side in Fig IOC. Then a first
plate 17 of the Fig. lOe type. Then a second plate 18 of the
type in the left side in Fig IOC. Then a friction reducing
pad 50. Then a second plate 18 of the type in the right side
in Fig IOC, i.e. with enlarged holes 24. Then an upper first
plate 17' of the Fig. lOd type, i.e. with enlarged holes 23a,
23b. (In the lower layer 17'' there could be a first lower
plate 17'' of the Fig. lOf type, this is not shown) . Then
another second plate 18 of the type in the right side in Fig
IOC, i.e. with enlarged holes 24. Then a friction reducing
pad 50. Then a second plate 18 of the type in the left side
in Fig IOC. Then a first plate 17 of the Fig. lOe type. Then
a second plate of the type in the left side in Fig IOC.
Thereby, the plates having increased diameter holes are
centrally located, and surrounded by friction reducing pads
50, and thereby allowed another tolerance of slip than the
plates surrounding them. Friction pads are arranged between
each of the first and second plates 17, 18, as is explained
for the embodiments described for figures 6 through 9 above.
The teaching of this disclosure has numerous advantages.
Different embodiments or implementations may yield one or
more of the following advantages. It should be noted that
this is not an exhaustive list and there may be other
advantages which are not described herein. One advantage of
the teaching of this disclosure is that it provides for a
passive damper with a characteristic or impedance that
changes with the magnitude of the movement that it is exposed
to. It is another advantage that it provides for a damper
that can be easily adapted to a specific need.
The term "clearance" as used in this description refers the
clearance between mating components and defines the amount of
motion that is possible between the mating components. The
term "clearance is similar to backlash or play, but in the
context of this description the terms have do not have a
negative meaning as the described clearance is desirable.
Although the teaching of this application has been described
in detail for purpose of illustration, it is understood that
such detail is solely for that purpose, and variations can be
made therein by those skilled in the art without departing
from the scope of the teaching of this application.
The term "comprising" as used in the claims does not exclude
other elements or steps. The term "a" or "an" as used in the
claims does not exclude a plurality. The single processor or
other unit may fulfill the functions of several means recited
in the claims.
Claims (9)
1. A passive damper for dampening relative movement between 5 members of a structure to which said damper can be connected, said damper comprising: at least a first set of parallel disposed plates, 10 and a second set of parallel disposed plates, said first set of plates and said second set of plates overlap one another in an alternating fashion at a rotational joint with damping pads between said plates, said rotational 15 joint comprises a pin or bolt inserted through apertures in said plates, a connection hole in each of the plates of the second set of plates for receiving a connection pin therein for connecting 20 the second set of plates to one of said members, wherein said connection holes in a selection of said plates of said 25 second set of plates being shaped and dimensioned to provide a predetermined amount of clearance with said connection pin so that said connection pin can move inside the connection holes of said selection of said plates to a predetermined extent without said selection of plates taking part in the 30 damping action of the damper.
2. A damper according to claim 1, wherein the shape and size of said connection holes in said plates outside said selection being dimensioned relative to the shape and size of the cross-section of said connection pin such that the plates in said second set of plates outside said selection have substantially no clearance between their respective connection hole and the connection pin.
3. A damper according to claim 1 or 2, wherein the shape and size of said connection holes in said plates of said selection being dimensioned relative to the shape and size of the cross-section of said connection pin such that plates in 10 the selection of plates have a first amount of substantial amount of clearance between their respective connection holes and the connection pin.
4. A damper according to any one of claims 1 to 3, wherein 15 the plates outside said section selection of plates move with said one member at any amplitude of movement of said one member and wherein said plates in said selection move with said one member only if the extent of the movement of said one member exceeds the clearance between the connection hole 20 concerned and the connection pin.
5. A damper according to any one of claims 1 to 4, wherein the connection holes of said selection of plates have an elongated outline or shape.
6. A damper according to any of one claims 3 to 5, comprising a further selection of plates within said selection of plates, the shape and size of the connection holes of the further selection of plates relative to the shape and size of 30 the cross section of the connection pin being such that the extent of clearance between the connection holes concerned and the connection pin is larger than said first substantial amount of clearance.
7. A damper according to any one of claims 1 to 6, wherein said plurality of damper pads comprises first selection of pads with a first effective contact area size and a second selection of pads with a second effective contact area size 5 different from said first effective contact area size.
8. A damper according to claim 7, wherein said damper pads are disk shaped with a central hole and the effective contact area is differentiated in a selection of damping pads through 10 the section of the outer diameter and/or the inner diameter of the damping pads concerned.
9. A passive damper for dampening relative movement between members of a structure to which said damper can be connected, 15 said damper comprising: a first set of parallel disposed plates, and a second set of parallel disposed plates, said first set of plates and said second set of plates overlap one another in an alternating fashion at a rotational joint with damping pads between said plates, said rotational joint comprises a pin or bolt inserted through apertures in 25 said plates, wherein apertures in a selection of said plates are shaped and 30 dimensioned to provide a predetermined amount of clearance with said pin or bolt so that said pin or bolt can move inside said aperture to a predetermined extent without said selection of plates taking part in the damping action.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DKPA201100546 | 2011-07-15 | ||
DKPA201100546 | 2011-07-15 | ||
PCT/EP2012/063714 WO2013010917A1 (en) | 2011-07-15 | 2012-07-12 | Passive damper |
Publications (2)
Publication Number | Publication Date |
---|---|
NZ619612A NZ619612A (en) | 2015-11-27 |
NZ619612B2 true NZ619612B2 (en) | 2016-03-01 |
Family
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