U.S. patent application number 15/685764 was filed with the patent office on 2018-03-01 for anti-entrapment device for scissor lifts.
This patent application is currently assigned to BLUESKY SOLUTIONS LIMITED. The applicant listed for this patent is BLUESKY SOLUTIONS LIMITED. Invention is credited to Leslie Darby, Kevin Jonathan Gale, Christopher Houlton, Matthew Ross.
Application Number | 20180057333 15/685764 |
Document ID | / |
Family ID | 57119816 |
Filed Date | 2018-03-01 |
United States Patent
Application |
20180057333 |
Kind Code |
A1 |
Gale; Kevin Jonathan ; et
al. |
March 1, 2018 |
Anti-entrapment Device for Scissor Lifts
Abstract
The present invention provides an anti-entrapment device for an
aerial lift having a basket or cage. The anti-entrapment device
comprises an elongate housing; two or more sensors housed within
said elongate housing and a switch activation device coupled to the
elongate housing. At least one of said two or more sensors is
positioned proximate an end of said elongate housing. Said switch
activation device is arranged at an angle to the orientation of
said sensor(s) positioned proximate the end of said elongate
housing. The sensors are arranged to provide a detection zone and
to detect obstacles within the detection zone. The sensors are
configured to facilitate the alerting of an operator standing in a
basket or cage to the presence of an obstacle that may potentially
strike the operator before the strike occurs, and the switch
activation device is configured to prevent further movement of the
basket or cage once the switch activation device is activated.
Inventors: |
Gale; Kevin Jonathan;
(Marlow, GB) ; Darby; Leslie; (Maghull, GB)
; Houlton; Christopher; (St Helens, GB) ; Ross;
Matthew; (Southampton, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BLUESKY SOLUTIONS LIMITED |
Lutterworth |
|
GB |
|
|
Assignee: |
BLUESKY SOLUTIONS LIMITED
Lutterworth
GB
|
Family ID: |
57119816 |
Appl. No.: |
15/685764 |
Filed: |
August 24, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B66C 15/06 20130101;
B66F 11/042 20130101; B66F 17/006 20130101; B66F 9/24 20130101;
B66F 11/04 20130101 |
International
Class: |
B66F 17/00 20060101
B66F017/00; B66F 11/04 20060101 B66F011/04 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 25, 2016 |
GB |
GB1614519.5 |
Claims
1. An anti-entrapment device for an aerial lift having a basket or
cage, the anti-entrapment device comprising: an elongate housing;
two or more sensors housed within said elongate housing, at least
one of said two or more sensors positioned proximate an end of said
elongate housing; a switch activation device coupled to the
elongate housing, said switch activation device arranged at an
angle to the orientation of said sensor(s) positioned proximate the
end of said elongate housing; wherein the sensors are arranged to
provide a detection zone and to detect obstacles within the
detection zone; the sensors configured to facilitate the alerting
of an operator standing in a basket or cage to the presence of an
obstacle that may potentially strike the operator before the strike
occurs, and the switch activation device configured to prevent
further movement of the basket or cage once the switch activation
device is activated.
2. The anti-entrapment device of claim 1, wherein the
anti-entrapment device includes two sensors, each sensor located
proximate an end of the elongate housing.
3. The anti-entrapment device of claim 2, wherein the elongate
housing is between 50 cm and 100 cm in length.
4. The anti-entrapment device of claim 2, further comprising a
plurality of braces configured to support the elongate housing in a
position above and parallel to a top rail of a basket or cage.
5. The anti-entrapment device of claim 2 wherein the switch
activation device comprises a pressure sensitive safety edge.
6. The anti-entrapment device of claim 2 further comprising an
operator warning system.
7. The anti-entrapment device of claim 6 wherein the operator
warning system comprises one or more warning lights mounted on the
elongate housing.
8. The anti-entrapment device according to claim 2 wherein the
sensors are ultrasonic sensors.
9. A basket or cage for a scissor lift, said basket or cage
comprising: an anti-entrapment device according to claim 2;
controls which permit an operator standing in the basket or cage to
manoeuvre it, the controls comprising: an emergency switch which
normally allows the flow of electricity and is operable to stop
electrical supply and prevent movement of the basket or cage, and a
function enable switch which is normally open to cut electrical
supply and prevent movement of the basket or cage and which must be
held closed by the operator to allow the flow of electricity and
enable the operator to operate the controls; an alarm which is
either audible, visual or audible and visual; a primary relay
connected to the function enable switch; a secondary relay
connected to the emergency switch; the primary and secondary relays
being controlled by a programmable control module connected to the
switch activation device, function enable switch and alarm; wherein
the control module is programmed to prevent movement of the basket
or cage by cutting electrical supply to the function enable switch
when the function enable switch is closed and the switch activation
device is activated, and to activate the alarm.
10. The basket or cage of claim 9, wherein if the electrical supply
to the function enable switch cannot be cut, the control module is
further programmed to prevent movement of the basket or cage and
activate the alarm by operating the emergency switch to cut the
electrical supply.
11. The basket or cage according to claim 10 wherein the function
enable switch is a dead man's handle.
12. The basket or cage according to claim 9 wherein the alarm is
located on an underside of the elongate housing of the
anti-entrapment device.
13. The basket or cage according to claim 9 wherein the scissor
lift has a horn and the alarm is an audible alarm which utilises
the horn.
14. The basket or cage according to claim 13 wherein the horn
sounds a unique sounding pattern.
15. The basket or cage according to claim 13 wherein the alarm is
linked to the horn via a communications link such as an RS232
interface.
16. The basket or cage according to claim 9 wherein the alarm is
visual and flashes for a period of time when the switch activation
device is activated.
17. The basket or cage according to claim 9 wherein the control
module is further programmed to perform a self-diagnostic test when
the anti-entrapment device is first turned on, and if the
anti-entrapment device fails the diagnostic test the control module
is programmed to activate a fault warning system.
18. The basket or cage according to claim 9 further comprising a
switch activation device reset switch connected to the control
module.
19. The basket or cage according to claim 18 wherein the reset
switch is located on said controls.
20. The basket or cage according to claim 9 wherein the control
module is further programmed to delay activation of the cutting
electrical supply to the function enable switch upon activation of
the switch activation device.
21. The basket or cage according to claim 20 wherein the delay is
approximately 0.4 seconds.
22. The basket or cage according to claim 9 further comprising an
information link to a data collection device.
23. The basket or cage according to claim 9 wherein additional
modules can be plugged into the control module.
24. The basket or cage according to claim 9 wherein the basket or
cage has a scissor lift control box and the control module is
housed within the scissor lift control box.
25. The basket or cage according to claim 9 comprising two or more
anti-entrapments devices; said two or more anti-entrapment devices
each comprising: an elongate housing; two or more sensors housed
within said elongate housing, at least one of said two or more
sensors positioned proximate an end of said elongate housing; a
switch activation device coupled to the elongate housing, said
switch activation device arranged at an angle to the orientation of
said sensor(s) positioned proximate the end of said elongate
housing; wherein the sensors are arranged to provide a detection
zone and to detect obstacles within the detection zone; the sensors
configured to facilitate the alerting of an operator standing in a
basket or cage to the presence of an obstacle that may potentially
strike the operator before the strike occurs, and the switch
activation device configured to prevent further movement of the
basket or cage once the switch activation device is activated;
wherein said anti-entrapment devices are positioned and connected
in series with one another.
26. The basket or cage according to claim 9 wherein the or each
anti-entrapment device is removably attached to the basket or
cage.
27. The basket or cage according to claim 9 wherein the or each
anti-entrapment device is permanently attached to the basket or
cage.
28. The basket or cage according to claim 25 wherein each
anti-entrapment device is located such that said elongate housing
does not protrude either into or out of the basket or cage.
29. The basket or cage according to claim 9 wherein the detection
zone extends approximately 210 cm above the floor of the basket or
cage.
30. The basket or cage according to claim 9 wherein the sensors do
not detect the position of the operator inside the basket or
cage.
31. The basket or cage according to claim 24, wherein the control
box comprise a control panel having one or more warning lights
mounted on the control panel.
32. The basket or cage according to claim 9, wherein the basket or
cage is a scissor lift basket or cage.
33. A scissor lift comprising a basket or cage according to claim
9.
34. A method of preventing the crushing of an operator standing in
a basket or cage of an aerial lift by an obstacle striking said
operator, said method comprising the steps: a. installing a
plurality of sensors to the basket or cage to establish a detection
zone, b. installing a switch activation device proximate a control
box of said aerial lift, c. connecting the sensors and the switch
activation device to a control module capable of preventing
movement of the basket or cage and/or alerting the operator to the
presence of an obstacle, d. monitoring the detection zone for an
obstacle entering the detection zone, e. sending a signal from the
sensors to the control module to instruct the control module to
alert the operator and/or to prevent movement of the basket or cage
when an obstacle is detected within the detection zone, f.
preventing movement of the basket or cage on activation of the
switch activation device.
35. The method of claim 34, wherein when the sensors detect an
obstacle and activate an alarm and/or warning system, the operator
can override the alarm and/or warning system by activating an
override procedure.
36. An anti-entrapment device for an aerial lift having a basket or
cage, the anti-entrapment device comprising: an elongate housing,
said elongate housing being between 50 cm and 100 cm in length; two
or more sensors housed within said elongate housing, at least one
of said two or more sensors positioned proximate an end of said
elongate housing; a switch activation device coupled to the
elongate housing, said switch activation device arranged at an
angle to the orientation of said sensor(s) positioned proximate the
end of said elongate housing, said switch activation device
comprising a pressure sensitive safety edge; and a plurality of
braces configured to support the elongate housing in a position
above and parallel to a top rail of a basket or cage.
Description
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS
[0001] The present application claims priority to United Kingdom
Patent Application No. GB1614519.5, filed Aug. 25, 2016, the
contents of which is incorporated herein by reference in their
entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to an anti-entrapment device
for scissor lifts. The present invention also relates a basket or
cage having such an anti-entrapment device, and a scissor lift
comprising the same.
BACKGROUND OF THE INVENTION
[0003] Aerial lifts are frequently employed for lifting operatives
to elevated working sites, for example to install overhead pipe
work during building construction. A typical aerial lift may
comprise a mobile elevated work platform (MEWP) having an
extendable boom which has an elevator basket or cage for housing
operatives securely to the end of the boom. Alternative aerial
lifts may comprise a MEWP having an extendable scissor linkage
which has an elevator basket or cage for housing operatives
securely to the end of the scissor linkage.
[0004] The basket or cage generally contains a control panel which
permits an operative standing in the basket or cage to manoeuvre
the work platform as desired. The aerial lift may be powered using
hydraulics powered by the MEWP's engine.
[0005] The control panel generally features an emergency stop
switch and a function enable switch which needs to be operated
before the controls can be operated. In boom lifts the function
enable switch is typically a footswitch which must be depressed to
activate the controls. In scissor lifts the function enable is
typically a dead man's handle. If the function enable switch is
released, the basket or cage is prevented from moving immediately,
but the MEWP's engine (which powers the hydraulics) continues to
run. If the emergency stop switch is activated then both the basket
is prevented from moving and, in most cases, the MEWP's engine is
stopped.
[0006] Unfortunately it is known that operators standing at the
control panel of the aerial lift can become trapped between the
basket/cage and an obstacle before they can either release the
function enable switch or activate the emergency stop. This is
known as an entrapment event. Accidents of this nature can be fatal
since the operator can be crushed.
[0007] The present applicants have previously described a safety
device comprising a tensioned cord or wire (EP2096078B1) and an
improved system comprising a pressure sensitive safety edge
(WO2012/001353). Activation of the safety device, which is located
proximate to the control panel, prevents movement of the basket or
cage by overriding the function enable switch. The effect being
equivalent to the operative having released the function enable
switch. A further improvement was disclosed in WO2013/093395
whereby the safety device is not "live" until the operator
activates the function enable switch.
[0008] The basket/cage of scissor lifts has more limited movement
than that of boom lifts, limited to up and down movement. As a
result, the issue of the possible entrapment of an operator in a
scissor lift and how to prevent such an event from occurring is
generally overlooked.
[0009] The present inventors have identified that it is preferable
to prevent an entrapment even before it occurs rather than after it
happens. Therefore it is an objective of the present disclosure to
provide an anti-entrapment device that can alert an operator to
possibility of an entrapment event occurring as well as prevent
crushing of the operator in the event that entrapment occurs.
SUMMARY OF THE INVENTION
[0010] According to a first aspect, there is provided an
anti-entrapment device for an aerial lift having a basket or cage,
the anti-entrapment device comprising: an elongate housing; two or
more sensors housed within said elongate housing, at least one of
said two or more sensors positioned proximate an end of said
elongate housing; a switch activation device coupled to the
elongate housing, said switch activation device arranged at an
angle to the orientation of said sensor(s) positioned proximate the
end of said elongate housing; wherein the sensors are arranged to
provide a detection zone and to detect obstacles within the
detection zone; the sensors configured to facilitate the alerting
of an operator standing in a basket or cage to the presence of an
obstacle that may potentially strike the operator before the strike
occurs, and the switch activation device configured to prevent
further movement of the basket or cage once the switch activation
device is activated.
[0011] The anti-entrapment device in accordance with the invention
provides a device that can alert an operator to possibility of an
entrapment event occurring, thus allowing the operator to take
evasive action as appropriate, as well as one which prevents
crushing of an operator in the event that entrapment of the
operator occurs.
[0012] In scissor lifts, it is known for operators to accidentally
engage the wrong control function, for example engage the lift
function of the basket or cage rather than the drive function of
the scissor lift. Such an error can lead to an accident, such as an
obstacle striking the operator. This could especially be serious
when the operator is looking or leaning over the side of the
basket/cage while trying to drive the scissor lift. The possibility
of an operator being crushed due to a mistake caused by engaging
the wrong control function is eliminated by the anti-entrapment
device of the invention as it first alerts the operator to the
presence of obstacles that may potentially strike the operator, as
such s/he is more aware of the risks in his environment. Secondly,
should the lift function be accidently engaged rather than the
drive function causing an obstacle to strike the operator,
entrapment of the operator would result in activation of the switch
activation device which results in the cessation of the basket or
cage thereby preventing crushing of the operator.
[0013] Preferably, the anti-entrapment device includes two sensors,
each sensor located proximate an end of the elongate housing. The
elongate housing is preferably between 50 cm and 100 cm in length.
In exemplary embodiments, the elongate housing is between 60 cm and
80 cm in length.
[0014] Preferably, the anti-entrapment device further comprises a
plurality of braces configured to support the elongate housing in a
position above and parallel to a top rail of a basket or cage.
[0015] Preferably, the switch activation device comprises a
pressure sensitive safety edge.
[0016] Preferably, the anti-entrapment device further comprises an
operator warning system. The operator warning system may comprises
one or more warning lights mounted on the elongate housing.
[0017] Preferably, the sensors are ultrasonic sensors.
[0018] According to a second aspect there is provided a basket or
cage for a scissor lift, said basket or cage comprising: an
anti-entrapment device according to the first aspect; controls
which permit an operator standing in the basket or cage to
manoeuvre it, the controls comprising: an emergency switch which
normally allows the flow of electricity and is operable to stop
electrical supply and prevent movement of the basket or cage, and a
function enable switch which is normally open to cut electrical
supply and prevent movement of the basket or cage and which must be
held closed by the operator to allow the flow of electricity and
enable the operator to operate the controls; an alarm which is
either audible, visual or audible and visual; a primary relay
connected to the function enable switch; a secondary relay
connected to the emergency switch; the primary and secondary relays
being controlled by a programmable control module connected to the
switch activation device, function enable switch and alarm; wherein
the control module is programmed to prevent movement of the basket
or cage by cutting electrical supply to the function enable switch
when the function enable switch is closed and the switch activation
device is activated, and activate the alarm.
[0019] Preferably, the control module is further programmed to
prevent movement of the basket or cage and activate the alarm by
operating the emergency switch to cut the electrical supply, if the
electrical supply to the function enable switch cannot be cut.
[0020] Preferably, the function enable switch is a dead man's
handle.
[0021] Preferably, the alarm is located on an underside of the
elongate housing of the anti-entrapment device.
[0022] In embodiments wherein the basket or cage forms part of a
scissor lift and the scissor lift has a horn, the alarm may be an
audible alarm which utilises the horn.
[0023] Preferably the horn sounds a unique sounding pattern.
[0024] The alarm may be linked to the horn via a serial
communications link such as an RS232 connection.
[0025] In exemplary embodiments, the alarm is visual and flashes
for a period of time when the switch activation device is
activated.
[0026] Preferably, the control module is further programmed to
perform a self-diagnostic test when the anti-entrapment device is
first turned on, and if the anti-entrapment device fails the
diagnostic test the control module is programmed to activate a
fault warning system.
[0027] In exemplary embodiments, the basket or cage further
comprises a switch activation device reset switch connected to the
control module. Preferably, the reset switch is located on said
controls.
[0028] The control module may be further programmed to delay
activation of the cutting electrical supply to the function enable
switch upon activation of the switch activation device. The delay
may be for any suitable period of time, preferably the delay is
approximately 0.4 seconds.
[0029] The basket or cage may further comprise an information link
to a data collection device.
[0030] Preferably, additional modules can be plugged into the
control module.
[0031] Preferably, the basket or cage has a scissor lift control
box and the control module is housed within the scissor lift
control box.
[0032] In exemplary embodiments, the basket or cage comprises two
or more anti-entrapments devices according to the first aspect. The
anti-entrapment devices are preferably positioned and connected in
series with one another.
[0033] The or each anti-entrapment device may be removably attached
to the basket or cage. Alternatively, the or each anti-entrapment
device may be permanently attached to the basket or cage.
[0034] It would be understood that in embodiments wherein the
basket/cage comprises a plurality of anti-entrapment devices, the
plurality of anti-entrapment devices could include a combination of
removably attached and permanently attached anti-entrapment
devices.
[0035] Advantageously, each anti-entrapment device is located such
that said elongate housing does not protrude either into or out of
the basket or cage.
[0036] Preferably, the detection zone extends approximately 210 cm
above the floor of the basket or cage.
[0037] Preferably, the sensors do not detect the position of the
operator inside the basket or cage.
[0038] In embodiments comprising a control box, the control box may
comprise a control panel having one or more warning lights mounted
on the control panel.
[0039] Preferably, the basket or cage is a scissor lift basket or
cage.
[0040] According to a third aspect, there is provided a scissor
lift comprising a basket or cage according to the second
aspect.
[0041] According to a fourth aspect, there is provided a method of
preventing the crushing of an operator standing in a basket or cage
of an aerial lift by an obstacle striking said operator, said
method comprising the steps:
[0042] installing a plurality of sensors to the basket or cage to
establish a detection zone;
[0043] installing a switch activation device proximate a control
box of said aerial lift;
[0044] connecting the sensors and the switch activation device to a
control module capable of preventing movement of the basket or cage
and/or alerting the operator to the presence of an obstacle;
[0045] monitoring the detection zone for an obstacle entering the
detection zone,
[0046] sending a signal from the sensors to the control module to
instruct the control module to alert the operator and/or to prevent
movement of the basket or cage when an obstacle is detected within
the detection zone;
[0047] preventing movement of the basket or cage on activation of
the switch activation device.
[0048] Preferably, when the sensors detect an obstacle and the
control module activates an alarm and/or warning system, the
operator can override the alarm and/or warning system by activating
an override procedure.
[0049] Other aspects are as set out in the claims herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0050] For a better understanding of the invention and to show how
the same may be carried into effect, there will now be described by
way of example only, specific embodiments, methods and processes
according to the present invention with reference to the
accompanying drawings in which:
[0051] FIG. 1 shows a MEWP with a scissor lift;
[0052] FIG. 2 shows a partial view of an embodiment of a
basket/cage of a scissor lift in accordance with the invention;
[0053] FIG. 3A shows a view from above of the basket/cage of FIG. 2
with the floor in a retracted configuration;
[0054] FIG. 3B shows a view from above of the basket/cage of FIG. 2
with the floor in an extended configuration;
[0055] FIG. 4A shows an isometric view of an embodiment of an
anti-entrapment device in accordance with the invention;
[0056] FIG. 4B shows a side view of the anti-entrapment device of
FIG. 4A;
[0057] FIG. 5A shows an isometric view of a section of a
basket/cage having the anti-entrapment device of FIG. 4A installed
thereon from the outside of the basket or cage;
[0058] FIG. 5B shows an isometric view of a section of a
basket/cage having the anti-entrapment device of FIG. 4A installed
thereon from the inside of the basket or cage;
[0059] FIG. 5C shows a side view of the section of the basket/cage
shown in FIG. 5A;
[0060] FIG. 5D shows a side view of the section of the basket/cage
shown in FIG. 5B;
[0061] FIG. 6 shows a side view of the embodiment of the
basket/cage in accordance with the invention;
[0062] FIG. 7A shows an isometric view of a basket or cage having
an anti-entrapment device in accordance with the invention
highlighting schematically the detection zone provided by each
sensor of the anti-entrapment device;
[0063] FIG. 7B shows a side view of the basket or cage of FIG. 7A,
highlighting the detection zone above the operator's head; and
[0064] FIG. 8 shows a block type circuit diagram for connection of
the anti-entrapment device into safety switches of the aerial
lift.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0065] There will now be described by way of example a specific
mode contemplated by the inventors. In the following description
numerous specific details are set forth in order to provide a
thorough understanding. It will be apparent however, to one skilled
in the art, that the present invention may be practiced without
limitation to these specific details. In other instances, well
known methods and structures have not been described in detail so
as not to unnecessarily obscure the description.
FIG. 1
[0066] With reference to FIG. 1, there is shown a mobile elevated
work platform (MEWP) 10 in the form of a scissor lift. The MEWP 10
has a drivable vehicle body 11 having wheels 12 and an extendable
scissor linkage 19. A basket or cage 20 is mounted on the free end
of the scissor linkage 19 and the basket/cage 20, in use, can be
raised or lowered relative to the ground as is well known. The
basket/cage 20 is shown in a raised condition. The scissor lift is
raised and lowered by any suitable means, typically operated by a
powered hydraulic system provided on the vehicle body 11 and
powered by the vehicle engine.
FIG. 2
[0067] With reference to FIG. 2 there is shown an embodiment of
basket/cage 20 for a scissor lift in accordance with the invention.
The basket/cage has a floor 21,21' which is surrounded by a safety
barrier 22. In the embodiment shown, the floor 21,21' is
extendable, although it may be understood that the floor of the
basket/cage may be of a fixed length.
[0068] The basket/cage is of a typically standard size known in the
art. There are two rails (a top rail 33 and a mid rail 34) and a
kick plate 35 surrounding the perimeter of the basket/cage 20, all
of which define the safety barrier 22. The top rail 33 is typically
approximately 110 cm above the floor 21,21' of the basket/cage,
such as approximately 102 cm from the floor 21,21' to the underside
of the top rail 33. The mid rail 34 is typically positioned
approximately 500 mm below the top rail 33, such as 566 mm from the
underside of the top rail 33 to the top side of the mid rail
34.
[0069] The basket/cage 20 is provided with controls 23, shown as a
control panel 24, which typically feature a control lever 27
whereby an operator (not shown) standing in the basket/cage 20 can
manoeuvre the scissor lift to a desired location by engaging the
drive function and/or raise or lower the basket/cage 20. The
controls 23 also comprise a function enable switch in the form of a
dead man's handle (not shown) which must be closed (depressed) by
the operator before the controls 23 are operational. The dead man's
handle may be coupled to the control lever 27 as known in the art.
When the dead man's handle is not depressed movement of the
basket/cage 20 ceases immediately although the MEWP's engine (which
powers the basket) usually continues to run.
[0070] An emergency stop switch 25 is shown on the controls 23
which also ceases movement of the basket/cage 20 when activated.
For most models of MEWP, the emergency stop switch 25
simultaneously shuts down the MEWP's engine.
[0071] In the embodiment shown, the control panel 24 is partially
protected by a side plate 30. The electronics of the controls 23
are typically housed directly beneath the control panel 24 in a
control box 32. The control panel may comprise one or more warning
lights mounted thereon.
[0072] The basket/cage 20 further comprises an anti-entrapment
device 40 and an alarm (not shown in FIG. 2).
[0073] An anti-entrapment device is a device to prevent entrapment
events which potentially endanger the operator. The anti-entrapment
device is not an anti-collision device. That is, the device is not
designed to prevent collision of the basket/cage with surrounding
obstacles.
[0074] The anti-entrapment device 40 comprises two or more sensors
42 arranged to provide a detection zone, and a switch activation
device 43. The switch activation device 43 is configured to prevent
further movement of the basket/cage 20 once the switch activation
device 43 is activated. The anti-entrapment device 40 is described
in more detail later on. In certain arrangements, the
anti-entrapment device is only functional after the function enable
switch is initially activated in order to make the controls
operational.
[0075] The alarm may be either audible, visual or audible and
visual.
[0076] A primary relay is connected to the function enable switch
and a secondary rely is connected to the emergency switch 25. The
primary and secondary relays are controlled by a programmable
control module connected to the switch activation device, function
enable switch, and alarm.
[0077] An advantage of the programmable control module is that it
can be expanded to incorporate additional "modules" such as
additional safety monitoring devices, a data recording device
etc.
[0078] Advantageously, the control module is dimensioned such that
it can also be housed within the control box 32. This is a
significant improvement over the prior art which had a control
module be housed outside of the control box, therefore taking up
more space within the basket.
[0079] In addition, having dimensions to fit inside the control box
means that the control module is smaller and lighter than in the
prior art, this is important particularly because aerial lifts have
a maximum load that can be lifted. A further advantage of housing
the control module within the control box is that it cannot be
accessed and tampered with as easily as in the prior art.
[0080] The control module is programmed to prevent movement of the
basket/cage 20 by cutting communication between the function enable
switch and the controls 23 when the function enable switch is
closed and the switch activation device 43 of the anti-entrapment
device 40 is activated. For example, the control module may be
programmed to cut electrical supply to the function enable switch
when the switch activation device 43 is activated.
[0081] Cutting communication between the dead man's handle
(function enable switch) and the controls 23 means that the
controls 23 would consider the dead man's handle not to be closed
even though the dead man's handle is depressed.
[0082] The initiation of the cutting of communication between the
function enable switch and the controls 23 or of electrical supply
to the function enable switch may be delayed by the control module
upon activation of the switch activation device 43.
[0083] Advantageously, employing a delay means that the sensitivity
of the switch activation device 43 can be fine tuned to reduce the
number of accidental activations. By employing a delay it is
possible to accidentally activate the switch activation device 43
and remove the activating signal quickly enough that the control
module does not consider the switch activation device 43 to have
been activated. For example, the operator can brush against the
switch activation device without cutting power to the controls. A
delay may be up to approximately 0.5 seconds such as 0.1, 0.2, 0.3,
0.4 seconds, for example 0.4 seconds.
[0084] In a preferred configuration, the delay is approximately 0.4
seconds.
[0085] The control module is further programmed to prevent movement
of the basket/cage 20 by operating the emergency switch 25 to cut
electrical supply to the controls in the event that the
communication between the function enable switch and the controls
23 cannot be cut.
[0086] The control module may also be programmed to activate the
alarm at the same time or soon after cutting communication between
the function enable switch and the controls 23 or electrical supply
to the function enable switch.
[0087] The basket/cage 20 further comprises a switch activation
device reset switch or button 29 connected to the control module.
In the embodiment shown, the reset switch/button 29 is located on
the controls 23. It would be understood that the reset
switch/button may be positioned in a different location in the
basket/cage, preferably proximate to the controls 23.
[0088] Typically the reset switch/button 29 must be activated
within 10 seconds of the accidental activation, for example within
1, 2, 3, 4, 5, 6, 7, 8 or 9 seconds. This period is known as the
pre-emergency stage.
[0089] The prevention of movement of the basket/cage 20 by the
control module may be overridden in the pre-emergency stage.
[0090] In general the reset switch/button 29 can be deployed during
an initial "pre-emergency" stage following activation of the safety
activation device 43. The pre-emergency stage is typically a period
of up to 10 seconds.
[0091] If the reset switch/button 29 is not deployed the full alarm
is activated and movement is prevented.
[0092] The alarm then operates until the anti-entrapment device is
reset.
[0093] In a preferred configuration during the pre-emergency stage,
the alarm has a different warning pattern.
[0094] In one arrangement, during the pre-emergency stage the
alarm's warning pattern comprises up to 5 sounds, flashes or sounds
and flashes in ten seconds, such as 1, 2, 3 or 4 flashes and/or
sounds in 10 seconds, for example 3 flashes and/or sounds.
[0095] A self-diagnostic test may be performed by the control
module when the anti-entrapment device is first turned on, this
usually occurs at the same time the engine of the MEWP is turned
on. If the anti-entrapment device fails the diagnostic test, the
control module is programmed to activate a fault warning
system.
[0096] The fault warning system alerts the operator to the fact
that the anti-entrapment device is either not working or fully
functional so that the operator can take alternate precautions.
[0097] The fault warning system does not cut power to the controls
meaning that the operator can chose to ignore the warning and
operate the aerial lift without the anti-entrapment device being
fully functional.
[0098] The anti-entrapment device must be restarted following
activation of the switch activation device 43.
[0099] The basket/cage 20 may further comprise an information link
to a data collection device and/or additional modules can be
plugged into the control module.
[0100] As is evident from the description above, the control module
can be programmed to perform certain actions on receipt of a given
signal. For example, on triggering of the switch activation device
the control module will send a signal to deactivate or override the
function enable device, to double check whether the signal worked
to cut power to the controls and if not to send a second signal to
the emergency switch. It will also activate the alarm. Similarly,
if the reset button is activated within a given period of time the
control module will reset the anti-entrapment device and allow the
controls to be functional again.
FIGS. 3A-B
[0101] With reference to FIGS. 3A and 3B there is shown a view of
the scissor lift basket/cage 20 with the extendable floor 21,21' in
a retracted configuration (FIG. 3A) and an extended configuration
(FIG. 3B).
[0102] The control box may stay with the fixed deck of the scissor
lift or may move with the sliding deck of the scissor lift as the
floor is extended depending on the configuration of the
basket/cage.
[0103] The configuration shown in FIGS. 3A and 3B is one wherein
the control box stays with the fixed deck.
FIGS. 4A and 4B
[0104] With reference to FIGS. 4A and 4B, an embodiment of an
anti-entrapment device 40 in accordance with the invention is
shown.
[0105] In addition to the sensors 42 and the switch activate device
43, the anti-entrapment device 40 comprises an elongate housing 41
and an operator warning system.
[0106] The elongate housing 41 is between 50 cm and 100 cm in
length. For example, the elongate housing is 75 cm in length.
[0107] The sensors 42 are housed in an elongate housing 41. In the
embodiment shown, the anti-entrapment device 40 comprises two
sensors 42. Each sensor is positioned proximate an end of the
elongate housing 41.
[0108] In one configuration the sensors 42 are located at a
distance of approximately 65 to 72 cm from each other such as 65,
66, 67, 68, 69, 70, 71 or 72 cm.
[0109] The detection zone defined by the sensors 42 is configured
to detect obstacles within the detection zone. That is to say that
the sensors are configured to facilitate the alerting of an
operator standing in the basket/cage 20 to the presence of an
obstacle that may potentially strike the operator before the strike
occurs. The detection zone will be described in more detail later
on.
[0110] The sensors do not detect the position of the operator
inside the basket or cage. Advantageously, this permits the
operator to undertake normal control of the basket or cage without
triggering the sensors.
[0111] In addition, the number and positioning of the sensors mean
that collision of an obstacle with the majority of the basket/cage
20 in not preventable i.e. the anti-entrapment device cannot work
as a viable anti-collision device.
[0112] In a preferred configuration, the sensors 42 are ultrasonic
sensors having a frequency of 39 to 41 kHz. However, it would be
understood that the sensors may be any suitable sensors such as
proximity sensors including, but are not limited to Doppler radar,
passive infrared, motion detectors, capacitive, capacitive
displacement, eddy-current, inductive, laser rangefinder, light
beam or curtain, magnetic, passive optical, passive thermal
infrared, photocell, Doppler effect, radar, reflection of ionising
radiation, sonar and ultrasonic sensors. In addition, the frequency
range of the sensors may be different to the one mentioned
above.
[0113] An advantage of proximity sensors is that they typically
have a high reliability and long functional life because of the
absence of mechanical parts and lack of physical contact between
sensor and the sensed object.
[0114] The maximum distance that a sensor can detect is defined as
its "nominal range". Some sensors have adjustments of the nominal
range or means to report a graduated detection distance.
[0115] In a preferred configuration, hysteresis of the sensors is
set to approximately 1 to 15 cm increments, such as 2, 3, 4, 5, 6,
7, 8, 9, 10, 11, 12, 13, or 14 cm, for example approximately 5 cm
increments. That is, a detected obstacle 100 cm away will be
detected at 95 cm away, 90 cm away etc when moving toward it and
will also be detected up to 105 cm away when moving away from it.
Hysteresis is a term relating to sensors which indicates the
sensor's response to objects that are getting closer as opposed to
those which are moving away from the sensor.
[0116] In a preferred configuration, the sensors 42 detect
obstacles approximately every 20 to 60 ms (milliseconds), such as
25, 30, 35, 40 45, 50 or 55 ms. For example every 40 ms.
[0117] In one configuration the debounce of the sensors 42 can
detect obstacles in 1 to 15 consecutive detections, such as 2, 3,
4, 5, 6, 7, 8, 9, 10, 11, 12, 13, or 14 detections. For example 2
consecutive detections. De-bounce is a term relating to sensors
which indicates the number of signals detected by the sensor before
an event output is passed on.
[0118] The debounce of the sensors 42 are arranged to have a
slightly different behaviour when the sensors 42 are moving closer
to an object than when the sensors 42 are moving away from an
object.
[0119] In one configuration the operator warning system is
activated following two consecutive detection signals from a single
sensor 42.
[0120] The operator warning system may be a visual, audible or
tactile warning system. For example, lights, sounds or
vibrations.
[0121] In an exemplary configuration, the operator warning system
comprises one or more warning lights. The one or more warning
lights are arranged on the elongate housing 41 and are configured
to indicate whether one of the sensors has detected an obstacle.
The one or more warning lights may also optionally indicate whether
the sensors are functional.
[0122] The warning light(s) may have different colours to indicate
different situations. For example, a green warning light to
indicate that a respective sensor is functional, an amber warning
light to indicate that an obstacle has entered the detection zone,
and a red warning light to indicate that the anti-entrapment device
is operating in override mode.
[0123] The switch activation device 43 is coupled to the elongate
housing 21 and arranged at an angle to the orientation of the
sensors (see FIG. 4B).
[0124] The switch activation device 43 is in the form of a pressure
sensitive safety edge. A safety edge can be classified as a "trip"
device. In general a safety edge or safety bumper is particularly
suitable for use on machines which stop immediately after removal
of power. A typical safety edge consists of an aluminium rail, a
safety contact, and a safety contact strip. The special shape of
the safety edge (rubber profile) protects the safety contact strip
from damage.
[0125] A protective covering or sleeve may be provided over the
switch activation device 43 and the elongate housing 41 to prevent
unwanted tampering with the switch activation device 43. Such an
arrangement is depicted in FIG. 2.
FIGS. 5A to 5D
[0126] With reference to FIGS. 5A to 5D, the mounting of the
anti-entrapment device 40 of FIGS. 4A and 4B on the basket/cage 20
will now be described.
[0127] The control box of a scissor lift may be portable allowing
its use in various different locations within the basket/cage or be
fixed in a permanent location within the basket or cage.
[0128] In arrangements where the control box of the basket/cage is
portable the basket/cage is provided with a mounting bracket on
which the control box may be mounted. This defines the home
position for the control box. The mounting bracket is generally
fixed to a vertical rail of the basket/cage.
[0129] While the mounting of the anti-entrapment device 40 will be
described with reference to a basket/cage having a portable control
box, it would be understood that it not limited thereto and can be
mounted in a basket/cage having a fixed control box position.
[0130] The mounting bracket for the control box 32 of the
basket/cage 20 is indicated by the reference numeral 53 in FIGS. 5A
to 5D. The same numerals as in the previously described figures are
use to identify identical components.
[0131] The anti-entrapment device 40 is positioned proximate the
home position of the control box 32. The location of the
anti-entrapment device 40 is such that it is not easily
unnecessarily triggered by an operator in the basket/cage.
[0132] The anti-entrapment device 40 comprises a pair of braces 44
configured to support the elongate housing 41 in a position above
and parallel to the top rail 33 of the basket/cage. While two
braces are shown being ustilised to support the elongate housing
41, it would be understood that more than to braces may be used or
a different support arrangement employed.
[0133] Positioning the anti-entrapment device 40 proximate the home
position means that it would be near the operator in situations
where an entrapment/crush incident is likely to take place when
accidental lifting not driving of the scissor lift occurs.
[0134] The braces 41 are spaced apart from each other at a distance
between 55 cm and 65 cm.
[0135] The braces 41 are configured to locate the elongate housing
41 at a distance of between 5 cm and 10 cm above the top rail 33.
The chosen spacing between the elongated housing and the top rail
may be varied dependent on requirements and may be greater or less
than the distance specified above.
[0136] The braces 41 are sized and shaped such that they support
the elongate housing 41 in such a way that it does not protrude
either into or out of the basket/cage 20.
[0137] One of the braces 41 is connected to the vertical rail 36 on
which the mounting bracket 53 is fixed. In the embodiment shown,
the brace 41 is releasably connected to the vertical rail 36 by
fasteners, such as nuts and bolts etc. It would be understood that
the bracket could instead be permanently connected to or integrally
formed with the vertical rail.
[0138] The second brace 41 is connected to a second vertical rail
52. The brace 41 may be releasably or permanently connected to the
second vertical rail 52, or be integrally formed with the second
vertical rail 52.
[0139] The second vertical rail 52 may be retrofitted to the
basket/cage or be pre-installed on the basket/cage.
[0140] In the embodiment shown, the second vertical rail 52 is
retrofitted to the basket/cage 20 and is releasably connected to
the mid rail 34 of the basket/cage 20. A clamp 55 is used to
connect the second vertical rail 53 to the basket/cage 20.
[0141] The clamp is shown as releasably connected to the mid rail
34, although it would be understood that it may be permanently
connected to the mid rail 34.
[0142] The braces 41 are shaped and positioned so as not to
interfere with a sliding top rail 33' of the basket/cage which
moves during extension and contraction of the floor 51,51' of the
basket/cage 20.
[0143] In the embodiment shown, the second vertical rail 52 is
pivotly mounted to the clamp 55 via a pivot pin 54. In this way,
the second vertical rail 52 will not prevent the handrails of the
basket/cage 20 from collapsing in a manner known in the art.
[0144] The anti-entrapment device is connected to the control
module 31 via any suitable means. For example, the connection may
be via a physical link such as wiring or via a wireless
connection.
FIG. 6
[0145] With reference to FIG. 6 there is shown a view of the
scissor lift basket/cage 20 from a side. In the embodiment shown,
the alarm 51 is mounted to an underside 50 of the elongate housing
41. It would be understood that the alarm may be positioned in a
different location.
[0146] In the embodiment shown, the alarm is in the form of a
visual alarm. The alarm may instead be an audible alarm or a
combined audible and visual alarm system.
[0147] The visual alarm, the visual alarm will flash when active
since it is known that a non-flashing alarm is less likely to
attract attention. The alarm will flash for a period of time when
the switch activation device is activated.
[0148] Generally visual alarms will be at least 50 lumens, such as
approximately 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160,
170, 180, 190, 200, 210, 220 230, 240, 250, 260 or 270 lumens, for
example over 230 lumens, such as about 240 lumens.
[0149] The flashing sequence of the visual alarm can be in a
regular or irregular pattern or can be arranged to send a message
such as a Morse code SOS.
[0150] In certain arrangements, an audible alarm is utilized in
addition to or instead of the visual alarm 51. Generally the
audible alarm will be at least 95 decibels, for example at least
96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109,
110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122,
123, 124, 125, 126, 127, 128, 129 or 130 decibels, such as
approximately 105 decibels.
[0151] The audible alarm may be in the form of a horn, for example
a vehicle horn.
[0152] Where the scissor lift is provided with a vehicle horn, the
audible alarm may utilise the horn so as to avoid the requirement
of installing a separate horn.
[0153] The audible alarm is linked to the vehicle horn via a serial
communications link, such as an RS232 lead.
[0154] Alternatively, a separate horn may be installed on the
basket/cage 20 as part of the combined audible and visual alarm
system.
[0155] The alarm or horn sounds a unique sounding pattern, for
example as Morse code SOS pattern--that is 3 short alarms followed
by three long alarms followed by three short alarms to replicate
the ...---... of Morse code.
[0156] The audible or visual SOS alarm preferably has a duration of
30 seconds or less, for example 29, 28, 27, 26, 25, 24, 23, 22, 21,
20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2
or 1 second. In an exemplary arrangement, the SOS alarm has
duration 10 seconds.
FIGS. 7A and 7B
[0157] With reference to FIGS. 7A and 7B there is shown the
basket/cage 20 with an operator 18 stood therein in front of the
control panel 24. The detection zone 48 is indicated generally, the
detection zone 48 being created by the two sensors 42 mounted on
the elongate housing (see earlier figures).
[0158] The sensors 42 each detect a conical shaped area which is
larger the further away from the sensor. While not shown in the
figures, the conical detection area of two or more sensors may
overlap closer or further away from the sensors.
[0159] Typically the detection zone 48 is arranged to detect
obstacles that come within 1 metre above the operator's head.
[0160] For example, if the operator is assumed to be 180 cm tall,
in one configuration the detection zone detects obstacles that are
within 300 mm of the operator's head when standing in the
basketicage. Therefore the detection zone is arranged to detect
obstacles approximately 210 cm (2100 mm) above the floor of the
basketicage.
[0161] In one configuration the sensors detect up to 80% of the
detection zone.
[0162] The sensors will have a detection angle of approximately 30
to 50 degrees, such as 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41,
42, 43, 44, 45, 46, 47, 48 or 49 degrees. For example approximately
40 degrees.
[0163] In one configuration, the conical detection area has a
diameter of approximately 550 to 600 mm at 800 mm away, such as
555, 560, 565, 570, 575, 580, 585, 590 or 595 mm. For example
approximately 582 mm at 800 mm away.
[0164] In another configuration, the conical detection area has a
diameter of approximately 625 to 675 mm at 900 mm away, such as
630, 635, 640, 645, 650, 655, 660, 665 or 670 mm. For example
approximately 655 mm at 900 mm away.
[0165] In yet another configuration, the conical detection area has
a diameter of approximately 700 to 750 mm at 1000 mm away, such as
705, 710, 715, 720, 725, 730, 735, 740 or 745 mm. For example
approximately 728 mm at 1000 mm away.
[0166] In yet another further configuration, embodiment the conical
detection area has a diameter of approximately 250 to 300 mm at 400
mm away, such as 255, 260, 265, 270, 275, 280, 285, 290 or 295 mm.
For example approximately 291 mm at 400 mm away.
[0167] The sensor range of the sensors 42 can be adjusted and is
set so that it does not detect obstacles too far away such that it
provides false readings thus leading to an operator not believing
in the system and thereby potentially ignoring real risk
situations.
[0168] In addition, the features of sensor detection envelop i.e.
angle, height, diameter etc., can be adjusted as required.
[0169] FIG. 8
[0170] With reference to FIG. 8 there is shown a simplified circuit
diagram for the anti-entrapment device.
[0171] In use, the anti-entrapment device is turned on when the
MEWP is powered up and performs a self-diagnostic test via the
control module 60. If the self-diagnostic test is failed the
operator is alerted by means of an alarm. If the test is passed the
anti-entrapment device is functional.
[0172] When the aerial lift is operational the operator activates
the function enable switch 82 which signals to the control module
60 to monitor for entrapment events. If an entrapment event is
detected by the switch activation device 72, a signal is sent to
the control module 60 to tell it to cut power to the function
enable switch 82 via a primary relay 88.
[0173] If the primary relay cannot cut power to the function enable
switch a signal is sent via the control module to a secondary relay
86 which cuts the power at the emergency switch 78.
[0174] In addition, when an entrapment event is detected by the
activation of the switch activation device 72, a further signal
from the control module is sent to activate the alarms 64, 80
within the basket (i.e. under the elongate housing) and at ground
level. The ground level alarm is activated via communications with
a ground level routing module 62.
[0175] The control panel features a reset button 70 which
communicates with the control module 60 to reset the alarms
following accidental triggering of the switch activation device.
For example, if pressed within 10 seconds of the triggering.
[0176] At each stage, error checking and fault reporting protocols
66 are in place to alert the operator that the anti-entrapment
device is not functional.
[0177] In the event that the function enable switch 82 is not
activated, the switch activation device 72 is ignored.
[0178] Additional anti-entrapment devices 92a (labeled as Pre crush
modules in FIG. 8) or additional modules 95 can be connected to the
control module, or the Base routing module 62, if desired.
[0179] In one embodiment the operator can override the
anti-entrapment device 92 by activating an override procedure.
[0180] In one embodiment the override procedure comprises pressing
an override button.
[0181] In one embodiment the override button is mounted on the
control panel.
[0182] In one embodiment the override button is mounted on the
elongate housing.
[0183] In one embodiment the override is automatically reset into
detection mode if the detection zone is clear of obstacles. That
is, if an obstacle is detected and the operator overrides the
anti-entrapment device, then the operator moves out of the
detection zone, the system is reset ready to detect the next
obstacle.
[0184] The present invention provides an improved method of
preventing the crushing of an operator standing in a basket or cage
of an aerial lift by an obstacle striking said operator. This is
because the present invention involves both installing a plurality
of sensors to the basket or cage to establish a detection zone and
installing a switch activation device proximate a control box of
said aerial lift, and connecting the sensors and the switch
activation device to a control module capable of preventing
movement of the basket or cage and/or alerting the operator to the
presence of an obstacle.
[0185] In this way, the operator is notified of obstacles which may
strike the operator and if an obstacle should strike the operator
resulting in an entrapment event further movement of the
basket/cage which would result in crushing of the operator is
prevented.
[0186] Continuously monitoring the detection zone for an obstacle
entering the detection zone means that the operator is alerted of
potentially hazardous situations while operating the aerial
lift.
[0187] Signals sent from the sensors to the control module would
instruct the control module to alert the operator of the presence
of an obstacle within the detection zone and to prevent movement of
the basket or cage when the obstacle is detected in a predetermined
range from the sensors.
[0188] Where the signal from the sensors results the control module
preventing movement of the basket or cage, a dwell time before
reactivation of the sensors may be employed after reactivation of
the controls in order to prevent an operator getting stranded due
the obstacle being in intermittently in the detection zone while
trying to move the basket/cage.
[0189] Movement of the basket or cage is stopped on activation of
the switch activation device. Reactivation of the controls would
only allow movement of the basket/cage in a downwards direction.
The control module may be programmed after activation of the switch
activation device to stop movement of the basket/cage in an upwards
direction (i.e. lifting) and immediately cause the basket/cage to
be lowered a predetermined distance or for a period of time at a
slow speed.
[0190] While the invention has been described with use of a single
anti-entrapment device fitted to the basket/cage, two or more
anti-entrapments devices as hereinbefore described may be used with
the basket/cage. In such a situation, the anti-entrapment devices
are positioned and connected in series with one another.
[0191] In the context of the present disclosure, anti-entrapment
device means a device for preventing or limiting the severity of
entrapment events. That is, an accident in which an operator is
struck by an object causing him to be pressed against the switch
activation device in a potential crushing position.
[0192] As employed herein aerial lift refers to any form of powered
extendable lift for enabling an operative to work at height, such
as a MEWP, cherry picker or scissor lift. Aerial lift does not
include a forklift truck or manually-powered (i.e. non-electrical)
lifts.
[0193] Basket or cage as employed herein refers to a working
platform with a safety barrier. The basket or cage is typically not
enclosed overhead.
[0194] Controls as employed herein refers to the entirety of the
controls via which the operator can manoeuvre the basket or cage
including the control lever on the control panel and the function
enable switch.
[0195] Emergency switch as employed herein refers to a switch or
button which, when activated, cuts all power to the MEWP platform
controls, overriding all other controls and preventing further
movement of the basket or cage.
[0196] Allows the flow of electricity as employed herein refers to
a closed (complete) circuit wherein electricity is free to move,
completing the circuit and allowing power to be supplied to the
controls of the basket or cage. That is, the controls of the basket
or cage are "live" and can be used to manoeuvre the basket or
cage.
[0197] Stop (or cut) electrical supply as employed herein means
that the circuit is open (broken), power is not supplied to the
controls of the basket or cage and therefore the basket or cage
cannot be moved.
[0198] Prevent movement as employed herein means that the basket or
cage cannot be manoeuvred. Typically this is due to the controls
not receiving power either because the function enable switch is
not activated or because the emergency switch has been
activated.
[0199] Function enable switch as employed herein means a switch
which must be activated for the controls to be live or functional.
For example, a dead man's handle must be held closed or a foot
switch must be depressed.
[0200] Dead man's handle as employed herein refers to a switch,
generally a lever, which acts as a safety device by shutting off
power when not held in place (held closed) by the operator.
[0201] Held closed by the operator as employed here refers to any
function enable switch which is held in the closed position, that
is, the position which enables the flow of electricity. Examples
include, but are not limited to, a dead man's handle which is held
in the active position and a foot switch which is depressed.
[0202] Alarm as employed herein refers to any alerting system
designed to draw attention to a specific problem or danger. Alarms
can be visual, audible, tactile (e.g. such as vibration alert) or
any other type of alarm.
[0203] Audible as employed herein refers to an alarm which can be
heard, for example, a klaxon or horn.
[0204] Horn as employed herein is a sound-making device used to
warn others of a hazard, such as the approach of a vehicle or of
its presence. Automobiles, trucks, ships, and trains are generally
required by law to have horns.
[0205] Unique sounding pattern as employed herein refers to a
specific repeated activation of the alarm, for example is a Morse
code SOS pattern--that is 3 short alarms followed by three long
alarms followed by three short alarms to replicate the ...---... of
Morse code.
[0206] RS232 as employed herein refers to a standard for serial
communication transmission of data. It formally defines the signals
connecting between a DTE (data terminal equipment) such as a
computer terminal, and a DCE (data circuit-terminating equipment,
originally defined as data communication equipment), such as a
modem. The RS-232 standard is commonly used in computer serial
ports. The standard defines the electrical characteristics and
timing of signals, the meaning of signals, and the physical size
and pinout of connectors.
[0207] Visual as employed herein refers to alarm which can be seen,
such as a light or beacon.
[0208] Flashes as employed herein means repeatedly turning on and
off. This can be in a regular or irregular pattern or can be
arranged to send a message such as a Morse code SOS.
[0209] Underside as employed herein means the bottom or underneath.
In use, the underside can be seen from the ground when the basket
or cage is elevated.
[0210] Switch activation device as employed herein refers to a
switch that activates, that is, triggers, the anti-entrapment
device to be deployed. While the invention has been described with
reference to a switch activation device in the form of a pressure
sensitive safety edge, it would be understood that it is not
limited thereto. Other types of switch activation device may be
utilized, including, but not limited to a tensioned cord or wire, a
safety bar, a laser or other beam or curtain of light which is
activated when the beam is broken.
[0211] Pressure sensitive safety edge as employed herein refers to
a sensor, which may be offered as a normally open contact. Safety
edges are typically flexible. If the moving part that includes the
safety edge or safety bumper strikes an operator (or vice versa)
the flexible safety edge is depressed under the applied load and
will send a signal for movement to be stopped.
[0212] Brace as employed herein refers to a mechanical fastening
arranged to hold the anti-entrapment device in position.
[0213] Proximate to as employed herein means very close to.
[0214] Reset switch as employed herein is a switch or button which
can be used to override the activity of the safety activation
device and ignore an accidental activation of the device.
[0215] Primary relay connected to the function enable switch as
employed herein means an electrically operated switch that
electrically connects the control module and the function enable
switch. It would be understood that an alternative connection means
that is capable of sending an electrical signal between the control
module and the function enable switch may be utilized. Generally,
the signal will be a signal to deactivate or override the function
enable switch, that is, to cut electrical supply and prevent
movement of the basket or cage.
[0216] Secondary relay connected to the emergency switch as
employed herein means an electrically operated switch that
electrically connects the control module and the emergency switch.
It would be understood that an alternative a connection means that
is capable of sending a signal between the control module and the
emergency switch may be utilized. Generally, the signal will be a
signal to activate the emergency switch, that is, to cut electrical
supply and prevent movement of the basket or cage.
[0217] Control module as employed herein refers to a component of
the anti-entrapment device which controls the interactions between
components.
[0218] Self-diagnostic as employed herein means the process of
diagnosing, or identifying the status of each component in the
anti-entrapment device. Typically the process involves checking
that power is supplied to each component, and where possible that
the component is working.
[0219] Warning system as employed herein means a different alarm
pattern to the emergency alarm seen or heard when the
anti-entrapment device is triggered by the switch activation
device.
[0220] Delay activation as employed herein refers to a delay
between receiving the activation signal from the switch activation
device and sending the signal to deactivate the function enable
switch.
[0221] Housed within as employed herein means that the control
module is arranged to have suitable dimensions that is can fit
entirely within the control box of the aerial lift.
[0222] Additional modules as employed herein refers to modular
units that can be connected to the present anti-entrapment device
to extend or improve its usefulness. Such modules include, but are
not limited to, additional sensors and data collection devices.
[0223] Plugged into the control module as employed herein refers to
the intention that such module will be easily connectable by the
unskilled person or a person with minimal training.
[0224] Communication link as employed herein refers to the
transmission of data from the control module to another module
(including the data collection device). Any suitable means of
transmission is intended to be covered including physical cabling,
such as ethernet, or wireless transmission including radio, wifi
and Bluetooth etc.
[0225] Data collection device as employed herein refers to a "black
box" type recorder intended to record information about collisions
and entrapments or near collisions/entrapments, operator data,
results of the self-diagnostic test among other things.
[0226] In the context of this specification "comprising" is to be
interpreted as "including".
[0227] Aspects of the disclosure comprising certain elements are
also intended to extend to alternative embodiments "consisting" or
"consisting essentially" of the relevant elements.
[0228] Where technically appropriate, embodiments of the invention
may be combined.
[0229] Embodiments are described herein as comprising certain
features/elements. The disclosure also extends to separate
embodiments consisting or consisting essentially of said
features/elements.
[0230] Technical references such as patents and applications are
incorporated herein by reference.
[0231] Any embodiments specifically and explicitly recited herein
may form the basis of a disclaimer either alone or in combination
with one or more further embodiments.
[0232] Sensors as employed herein means a device that detects a
change in events. In the present context the event to be detected
is the presence of an obstacle.
[0233] Ultrasonic as employed herein means sound at a frequency
above the audible limit of human hearing, that is, above 20,000
Hz.
[0234] Upward facing as employed herein means the sensors point
substantially perpendicular to the ground or to the surface on
which the sensors are mounted. That is, the sensors are
vertical.
[0235] Does not protrude either into or out of the basket or cage
as employed herein means that it is dimensioned such that it is
neither taller nor wider than the surface on which it is
mounted.
[0236] Removably attachable as employed herein means that the
anti-entrapment device can be attached to the aerial lift
temporarily. Advantageously this means that the anti-entrapment
device can be fitted or removed from the lift as desired.
[0237] Detection zone as employed herein refers to the totality of
all of the sensors sensing capacity.
[0238] Obstacle as employed herein means an object substantially
large and solid enough to be detected by the sensors as a danger to
the operator.
[0239] Strike as employed herein means to hit and potentially
injure the operator.
[0240] Operator as employed herein means a man or woman standing in
the basket or cage of the aerial lift, typically standing in front
of the control panel.
[0241] Operator warning system as employed herein means a system
designed to alert the operator of various factors, including but
not limited to, an obstacle has entered the detection zone, the
anti-entrapment device is running in override mode.
[0242] Fault warning system as employed herein means a system
designed to alert the operator of a fault with the anti-entrapment
device.
[0243] Warning lights as employed herein means one or more lights
that can show different states, for example different flash
patterns or different colours.
[0244] Alert the operator to the presence of the obstacle as
employed herein means that a visual audible or tactile warning is
transmitted to the operator to indicate that an obstacle has
entered the detection zone.
[0245] Prevent movement as employed herein means that the basket or
cage cannot be manoeuvred. Typically this is due to the controls
not receiving power either because the function enable switch is
not activated or because the emergency switch has been
activated.
[0246] Override as employed herein means that the operator can
choose to continue to work with an obstacle inside the detection
zone. Advantageously this permits the operator to work on an
obstacle if desired. For example, if the basket/cage needs to be
within a shorter distance to an obstacle than the sensors would
allow before activating the control module to stop movement of the
basket/cage.
* * * * *