Note: Descriptions are shown in the official language in which they were submitted.
CA 02440801 2003-09-12
Braking Mechanism for a raisable platform assembly
Background of the invention
The present relates to a braking mechmism for a raisable platform. More
particularly,
the invention relates to an automatic braking mechanism for preventing falling
of a
raisabIe platform in the case of a malfunction.
lRaisable platforms have been in use for the purposes of raising people and
goods. One
example use would be the elevators used in tall buildings. One problem with
such
raisable platforms is the chance of failure. On type of failure would be
breakage in the
raising mechanisms of the platforms. If these mechanisms fail then the
platform may
be allowed to rapidly fall from its elevated position. This may cause great
damage to
the raisable platform mechanism, as well as to the goods that were being
raised.
For this reason, most raisable platform assemblies are fitted with emergency
brakes
and other braking mechanisms which are designed to automatically start to
function in
the case of a malfunction in the platform assembly.
These emergency brakes can often get complicated to manufacture, and often
require
additional braking surfaces to be installed along with the raisable platforms.
While xaisable platforms may be constructed very simply using noting but a
platform
which is raisable by a winch, it is often useful to provide the platform with
additional
support measures. These additional support measures can provide greater
stability and
support. These additional support measures may for instance take the form of
threaded
support rods. These threaded support rods may be attached to the raisable
platforms
by way of nuts. Thus, the turning of the threaded support rods may raise and
lower the
raisable platform, or more commonly, the threaded support rods will rotate in
response to the raising and lowering of the platform. This type of structure
provides
additional support for a raisable platform and is simple to implement.
CA 02440801 2003-09-12
Brief description of the drawings
Figure 1 shows an example embodiment of a raisable platform assembly fitted
with an
example embodiment of braking mechanism according to the present invention
S
Figure 2 shows a close-up of the braking mechanism shown in figure 1 during
normal
operation.
Figure 3 shows a close-up of the braking mechanism shown in figure 1 when the
braking mechanism is activated,
Figure 4 shows a top view of the braking mechanism sholv~~ in figure 1 during
normal
operation.
1 S Figure 5 shows a top view of the braking mechanism shown in figure 1 when
the
braking mechanism is activated.
Detailed Description
Referring to the fig l, we can see one example embodiment of a raisable
platform
assembly equipped with a breaking mechanism according to the present
invention. As
may be seen the raisable platform assembly comprises a raisable platform 10
mounted
on threaded support rods 20 and 22. The platform 10 is mounted on the threaded
support rods 20 and 22 such that when the platform 10 is raised or lowered the
threaded support rods 20 and 22 will rotate.
Any mounting means between the rods 20 and 22 and the platform 10 can be used,
as
long as any up and down movement of the supported platform 10 allows the rod
20,
22 to freely rotate about themselves. Also, the mounting means must allow the
transmission of the load and movement of the unsupported platforin 10 to the
rods 20
and 22. In the shown embodiment the treaded rods 20 and 22 cooperate with the
platform 10 via a male (rods 20 and 22) female (threaded hole in the platform
10)
connection.
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CA 02440801 2003-09-12
While the example embodiment shown in Fig 1 has two threaded support rods 20
and
22, the raisable platform assembly may be utilized with any number of threaded
support rods. Other embodiments may for instance have four threaded support
rods,
on at each corner of the platform.
Also attached to the raisable platform 10 are support cables 30 and 32. The
support
cables 30 and 32 are attached to winding rod 40 such that rotation of winding
rod 40
may wind or unwind the support cables. Therefore, the rotation of the winding
rod 40
allows for the raisable platform 10 to be moved in a up and down direction by
winding and unwinding the support cables 30 and 32. The winding rod 40 may
further
be attached to a reversible motor 50, which rotates the wrinding rod in both
directions.
In the shown embodiment of Figure 1, two support cables 30 and 32 are shown,
but
the present invention could comprise only one cable attached at strategic
locations on
the platform 10, or could comprise more than one cable.
The raisable platform assembly also has breaking mews 60, which are adapted to
stop
the platform 10 in the case of dangerous decent speeds such as when one of the
cable
30 and 32 breaks.
As may be seen in greater detail in Fgures ? and 3, the braking means may 60
comprise multiple components, In a first aspect, the braking means 60
comprises a
bolt 64 which may be attached to the threaded support rods 20 and 22, or may
alternately be formed integral therewith. The bolt 64 is attached such that as
the
threaded rod 20 and 22 turn, the bolt 64 will tunz as well.
Second, the braking means 60 may comprise a stopping means 66 configured such
as
allow the bolt 64 to freely rotate above it. However, if the bolt 64 is moved
to the
level of the stopping means 66, then the stopping means 66 will prevent the
bolt from
3U turning.
Finally, the braking means may comprise a biasing means 62 Iike a spring,
which
gives the threaded support rod 20 and 22 a bias so as to keep the bolt 64 at a
height
where the stopping means 66 does not interfere with bolt 64.
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CA 02440801 2003-09-12
The braking mechmism 60 functions as follows. During normal utilisation, the
platform 10 is loaded, algid may then be raised and lowered using motor 50 and
support cables 30 and 32. In this. case the biasing means 62 will exert cuff
cient force
on the threaded support rods 20 and 22 to keep the bolts 64 out of the way of
the
stopping means 66.
In the case of a malfunction however, such as the breaking of at least one of
the
support cables 30 and 32 or a malfunction in the motor, the raisable platform
10 may
lose start to fall rapidly due to its one weight which is combined with the
weight of
any load placed thereon. In this case the weight of the platform 10 and its
load will
press downwards on the threaded support rods 20 and 22 as they are rotated by
the
decent of the platform 10. The induced presswe of the platform 10 on the
threaded
support means 20 and 22 will overcome the bias of the biasing means 62. The
bolt 64
will then be brought down to the level of the stopping means 66. Then as the
threaded
support means 20 and 22 rotate the bolt 64 wilt come into contact with the
stopping
means 66, thus halting the rotation of the threaded support means 20 and 22
and
thereby the decent of the platform 10.
Moving on to figures 4 and 5, we can see a top view of the braking mechanism
60. In
figure 4 we can see that the brakvig mechanism may be fitted with multiple
bolts 64.
The stopping means 66 may also be fitted with a kill switch so that when the
braking
means is activated the kill switch will automatically stop the motor 50. The
kill switch
may be activated by providing the stopping means 66 with a button 68. This
button 68
may be placed such that if one of the bolts 64 comes into contact with the
stopping
means 66 the button will be pressed (see fig 5). The pressing of the button 68
then
activates the kill switch and stops the motor 50.
While the braking mechanism of the invention has been described using the
example
embodiment shown in the figures, other embodiments are envisioned. In other
embodiments, the biasing means may for instance be a wire, which suspends the
threaded support rod from the top of the raisable platforni assembly. This
wire could
be selected to have a tensile strength such that it would break if subjected
to the full
weight of the platform.
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CA 02440801 2003-09-12
In another example embodiment, the threaded support rod or rods could be
suspended
from an extendable spring at the top, rather than supported by a compressible
spring at
the bottom.
In yet another example embodiment, the threaded support rods may be fitted
with
magnets, either on the top where in which case the magnets could attract to
magnets
placed on the top of the raisable platfonn assembly, or on the bottom in which
case
the magnets would repulse from magnets placed on the bottom of the raisable
platform assembly.
In another example embodiment, the spring might be replaced by a mechanism
similar
to those used for shock absorption, for instance in vehicles.
In another example embodiment, the spring might be removed and the bolt could
be
placed on hinges and biases to a position parallel with the threaded support
rod. The
bolt and the bias would be such that in the case of a rapid rotation of the
threaded
support rod, such as in the case of a malfunction, the result would allow
su~cient
centrifugal force to cause the bolt to overcome the bias and displace to a
position at an
angle to the threaded support rod, thus coming in to the path of a stopping
mews.
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