U.S. patent application number 14/982279 was filed with the patent office on 2016-04-21 for vehicle access system.
The applicant listed for this patent is Barjoh Pty Ltd. Invention is credited to Nathan John Ellement.
Application Number | 20160108672 14/982279 |
Document ID | / |
Family ID | 37531891 |
Filed Date | 2016-04-21 |
United States Patent
Application |
20160108672 |
Kind Code |
A1 |
Ellement; Nathan John |
April 21, 2016 |
VEHICLE ACCESS SYSTEM
Abstract
A vehicle access system and method with retractable access
means, e.g., ladder or stairs and a retracting mechanism therefor.
Force applied to the access means is sufficient to retract the
access means from a fully deployed position to a partially
retracted position but not sufficient to not be physically resisted
by a user during at least part of the retraction. With the access
means in a fully retracted position, force exerted on the retracted
access means can be sufficient to hold the access means in a
retracted position without the need for auxiliary restraining
means.
Inventors: |
Ellement; Nathan John;
(Oakford, AU) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Barjoh Pty Ltd |
Oakford |
|
AU |
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|
Family ID: |
37531891 |
Appl. No.: |
14/982279 |
Filed: |
December 29, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11917701 |
May 23, 2008 |
9238941 |
|
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PCT/AU2006/000846 |
Jun 16, 2006 |
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14982279 |
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Current U.S.
Class: |
182/64.1 |
Current CPC
Class: |
E06C 5/06 20130101; E06C
5/04 20130101; E06C 7/02 20130101; B60R 3/02 20130101 |
International
Class: |
E06C 5/04 20060101
E06C005/04; E06C 7/02 20060101 E06C007/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 16, 2005 |
AU |
2005903162 |
Claims
1. A vehicle access apparatus comprising: an access device
including a ladder or stairs configured and arranged to, when
mounted to a vehicle, rotate about a pivot axis relative to the
vehicle; and a retraction mechanism configured and arranged to
retract the access device from a deployed position to a final
retracted position, the retraction mechanism including an actuator
and a linkage, the actuator being connected to and configured and
arranged to operate the linkage, the linkage being connected to the
access device and configured and arranged to, using a linear force
provided by the actuator and a geometry of the linkage, rotate the
access device about the pivot axis by applying a rotational force
to the access device that is sufficient to retract the access
device from a fully deployed position to a partially retracted
position, and by increasing the applied rotational force during
retraction between the partially retracted position and the final
retracted position.
2. A method of retracting an access device about an axis of
rotation from a deployed position to a final retracted position,
the method including the steps of: a) applying a first torque to
the access device through a linkage arrangement between an actuator
applying a linear force and the access device during an initial
portion of a retraction phase of said access device to rotate the
access device about the axis of rotation from a fully deployed
position to a partially retracted position, the applied first
torque being equal to or greater than a minimum force required to
rotate the access device toward the final retracted position; b)
subsequently applying a second torque to the access device through
the linkage arrangement during a secondary portion of the
retraction phase after the initial portion of the retraction phase
of the access device, the second torque being greater than the
first torque; and c) wherein applying the first torque and applying
the second torque includes translating the applied linear force to
become the first torque and the second torque, utilizing the
geometry of the linkage arrangement to provide the second torque as
being greater than the first torque.
Description
RELATED PATENT DOCUMENTS
[0001] This patent application is a continuation under 35 U.S.C.
.sctn.120 of U.S. patent application Ser. No. 11/917,701 filed on
May 23, 2008; which is the national stage filing under 35 U.S.C.
.sctn.371 of International Application No. PCT/AU2006/000846 filed
on Jun. 16, 2006; which claims foreign priority benefit under 35
U.S.C. .sctn.119/365 of Australian Patent Application No.
2005903162 filed on Jun. 16, 2005; each of these patent documents
is fully incorporated herein by reference.
FIELD OF THE INVENTION
[0002] This invention relates to access systems for vehicles,
specifically the access system for large earth moving
equipment.
BACKGROUND OF THE INVENTION
[0003] Access systems for large earth moving equipment often
incorporate a set of deployable stairs so that the operator can
climb up into the cab without climbing a vertical ladder that may
have a negative inclination if the equipment is not parked on level
ground.
[0004] Once the operator is on the machine the operator retracts
the stairs so that they are not hanging down and the ground
clearance of the machine is increased thus minimizing the
probability of the stairs being damaged by contacting rocks when
the machine is in motion.
[0005] The stairs need to be retracted so that other personnel
cannot climb up onto the machine without the operator's knowledge.
Should a person be on the stairs without the operator's knowledge
then the possibilities for injury to that person are numerous. The
possible injuries could range from overbalancing the person to
crushing or trapping the person between the moving parts of the
equipment and the adjoining bodywork of the equipment.
[0006] The systems used for retracting the stairs can vary but
generally they rely on either an electric or hydraulic system that
is manually actuated by the operator.
[0007] Should an emergency occur such as a fire it is necessary for
the operator to activate a switch to lower the stairs to evacuate
the machine or find an alternative way off the machine or
equipment. This can be a particular problem if there is a fire in
the vicinity of the stair operating switch.
[0008] Should the operator forget to retract the stairs and drive
the machine off, it is possible to destroy the stairs, causing an
expensive repair, downtime and generating safety issues, resulting
from damage to an emergency exit.
[0009] Another known problem of prior art ladder retraction systems
is that, when retracted, the ladder is either held retracted by
hydraulic/pneumatic pressure, such as provided by the lifting
cylinder, or once retracted a locking pin is used to lock the
ladder in place. The locking pin itself can be driven by a small
hydraulic/pneumatic cylinder.
[0010] Problems with such systems are typically associated with
bounce. The ladder can bounce during movement of the vehicle,
causing failure of the lifting system. Also, damage caused to the
locking pin by ladder bounce can result in failure of the locking
pin mechanism.
[0011] Where the vehicle has an interlock system, such as a
proximity switch, connected to the ladder retraction mechanism or
to the locking pin actuating mechanism to prevent movement or
starting the vehicle until the interlock is operated, ladder bounce
can result in the switch operating thereby stopping or shutting
down the vehicle unexpectedly. This results in excess downtime of
the vehicle and loss of productivity.
[0012] With the aforementioned in mind, it is an object of the
present invention to provide a system for retracting a ladder that
allows a user to physically halt initial retraction but provides
sufficient force to maintain the ladder retracted when
retracted.
SUMMARY OF THE INVENTION
[0013] With this in view, there is provided a vehicle access system
including an access means and a retracting mechanism for the access
means, wherein a force applied to the access means is sufficient to
retract the access means from a fully deployed position to a
partially retracted position but not sufficient to not be
physically resisted by a user during at least part of the
retraction.
[0014] Thus, advantageously, an access system for a vehicle is
provided that will allow a user to overcome the retraction forces
during at least part of the retraction process to thus prevent
further retraction, and optionally commence re-deployment of the
stairs to alleviate risk of injury to the user. It will be
appreciated that a user wishing to prevent retraction of the stairs
will be able to safely apply sufficient force or weight to overcome
retraction forces and thus halt or reverse the retraction
process.
[0015] It will be appreciated that the term access means may
encompass stairs, steps and ladders for accessing vehicles.
[0016] A further aspect of the present invention provides a
retractable access system for a vehicle including an access means
and a retracting mechanism for said access means, wherein an
applied moving force is translated into a variable force for
retracting the access means wherein torque generated to retract the
access means exceeds torque required to retract the access means by
an amount that is able to be resisted by a user for a portion of
the retraction phase and increases to a greater force for a latter
portion of the retraction phase. Preferably, when the access means
is fully retracted, a force may be exerted on the retracted access
means sufficient to hold the access means in a retracted position
without the need for auxiliary restraining means.
[0017] Preferably torque provided to retract the access means may
vary through at least part of the retraction cycle.
[0018] The torque generated may vary throughout the retraction
cycle so that the torque provided to retract the access means from
0-70% of the retraction cycle just exceeds the required torque
necessary to retract the access means, and between 70-100% of the
retraction cycle the torque generated may increase such that when
the access means is fully retracted the torque applied to the
access means is sufficient to hold the access means in the
retracted position without the need for auxiliary restraining
means.
[0019] This provides the advantage that when the access means are
within reach or use of ground personnel, the forces retracting the
access means may be countered by the user. When the access means
are out of the reach of ground personnel, the force applied through
the retraction mechanism increases so that the access means are
firmly held in the retracted position.
[0020] Preferably the retracting/deploying system may be connected
into a hydraulic pilot control circuit and/or a hand brake
hydraulic circuit of the vehicle. This has the advantage that when
the hand brake is released the access means are automatically
retracted. When the park brake is applied or if there is a
hydraulic failure the access means are deployed.
[0021] The geometry of the parts of the linkage is configured to
provide a required torque profile.
[0022] A further aspect of the present invention provides a method
of retracting an access means including the steps of;
[0023] a) applying a first lifting force during an initial portion
of a retraction phase of a deployed access means, the applied first
lifting force being equal to or greater than a minimum force
required to lift the access means,
[0024] and b) subsequently applying a second lifting force during a
secondary portion of the retraction phase of the deployed access
means, the second lifting force being greater than the minimum
required to lift the ladder.
[0025] Preferably the first lifting force may be less than a manual
effort required to retard retraction of the access means.
Preferably the manual effort may be sufficient to reverse
retraction of the access means and commence re-deployment
thereof.
[0026] Preferably the second lifting force (torque) may diverge
(and increase) compared to the required lifting force during the
secondary portion of the retraction phase.
[0027] Preferably the initial portion of the retraction phase may
be about two thirds of the entire retraction phase from
commencement to fully retracted.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] FIG. 1 is a side view of an embodiment of the present
invention showing the mechanical arrangement of the retracting
mechanism.
[0029] FIG. 2 is a graph showing the torque required and the torque
applied to retract the stair from +45.degree. to -90.degree.
according to an embodiment of the present invention.
[0030] FIG. 3 is a graph showing the torque required and the torque
applied to retract the stair from +60.degree. to -120.degree.
according to an embodiment of the present invention.
[0031] FIG. 4 shows a graph of excess lift torque for a ladder
retracting through 90.degree. in accordance with an embodiment of
the present invention.
[0032] FIG. 5 shows a graph of excess lift torque for a ladder
retracting from 45.degree. extended to -90.degree. retracted,
according to an embodiment of the present invention.
[0033] FIGS. 6a to 6d show a series of images of a set of vehicle
stairs being retracted from a deployed position to a fully
retracted position according to an embodiment of the present
invention.
DETAILED DESCRIPTION
[0034] It will be convenient to describe the present invention with
reference to the accompanying Figures and examples that illustrate
possible arrangements of the present invention.
[0035] FIG. 1 shows a preferred embodiment where the stairs 10
operate with rotation around a fixed point at the inboard end of
the stairs 10. It would be clear to a person skilled in the art
that other possible arrangements are possible.
[0036] The access system consists of a set of access stairs 10
actuated by a retraction mechanism 25.
[0037] The stairs 10 are relatively conventional for large
earthmoving equipment and may have a normal operating angle of
between 45.degree. and 70.degree. relative to the horizontal
direction and retract through an arc of between 90.degree. and
180.degree.. The stairs 10 may also include a hand rail 27 and
textured treads (not shown) to provide a secure access way to the
equipment.
[0038] The retraction mechanism 25 has been chosen to as to provide
a unique non-linear torque response to the stairs 10 from a fixed
force linier output. In the present example the linier force is
provided by a hydraulic ram 40. The retraction mechanism 25 is
optimized to provide a varying torque to lift the stairs 10
depending on where in the arc of retraction the stairs 10 are. When
the stairs 10 are in the fully deployed position such that an
operator could use the stairs 10 to access the equipment the torque
force applied to retract the stairs 10 is enough to raise the
stairs 10, however the torque applied only exceeds the torque
required by a relatively small amount so that a person would be
able to stop the stairs 10 from retracting. This has the advantage
that should a person be on the stairs 10 or holding the stairs 10
when they are retracted by the equipment operator, the stairs 10
will not retract and injure the person holding the stairs 10.
[0039] Once the stairs 10 are retracted above the reach of any
ground personnel or equipment that may get caught up with the
stairs 10 the torque applied to the stairs 10 is increased relative
to the torque required. The point of increasing torque is set by
the geometry of the retraction mechanism 25. The point of
increasing torque is determined during design of the retraction
mechanism 25 and may vary according to the intended application.
For example a small earth moving machine or equipment may have the
stair travel through 70.degree. before the stairs 10 are out of
reach of ground personnel and therefore may be designed to have the
torque increase at about this point. If the stairs 10 are being
fitted to a larger machine the stairs 10 may only need to be
retracted through 45.degree. or even less before they are out of
reach of ground personnel.
[0040] The increase of torque applied to the stairs 10 provides an
advantage in that by the time the stairs 10 are in the fully
retracted position there is a larger force holding the stairs 10 in
the fully retracted position. This increased force applied to the
stairs 10 eliminates the need for any additional retention
mechanisms to be installed to stop the stairs 10 moving
uncontrollably when the equipment is in operation.
[0041] Another advantage of the retraction mechanism 25 is that
should the stairs 10 be restrained, by contact with fixed objects
for example rocks or other vehicles, the retraction mechanism 25
will not be damaged as the torsional force available to retract the
stairs 10 is initially not significantly greater than the force
required in retracting the stairs 10.
[0042] FIG. 1 shows a general arrangement of the retraction
mechanism 25. The stairs 10 are pivotally mounted to the equipment
at the stair main pivot 30. The retraction mechanism 25 includes a
hydraulic ram 40, having a first end 45 pivotally connected to a
hydraulic ram 40 via mounting bracket 50 at the hydraulic ram pivot
46. The hydraulic ram bracket 50 is affixed to the stair 10 at some
distance along the stair 10 remote from the stair main pivot 30
that is located on the earth moving equipment (not shown). The
hydraulic ram bracket 50 is designed to move the hydraulic ram
pivot some distance from the stair 10. This distance is called the
hydraulic ram offset 100.
[0043] The second end 47 of the hydraulic ram 40 is pivotally
connected to two linkages. One of the linkages is called the ram
stair linkage 55. The ram stair linkage 55 runs from the second end
47 of the hydraulic ram 40 to the intermediate pivot 56 located on
the stairs 10 at a point between the main pivot 30 and the
hydraulic ram mounting bracket 50.
[0044] The second linkage connected to the second end 47 of the
hydraulic ram 40 is called the ram body linkage 57. The ram body
linkage 57 runs from the second end 47 of the hydraulic ram 40 to
the body pivot point 60 located on the earth moving equipment at
some point offset from the stair main pivot 30.
[0045] When in operation the hydraulic ram 40 extends and applies a
force between the ram pivot 46 and the equipment through the ram
body linkage 57. As the ram pivot 46 is offset by the use of the
hydraulic ram mounting bracket 50 (the hydraulic ram offset 100)
and the ram body linkage 47 is mounted on the earth moving
equipment at the body pivot 60 (offset from the main pivot 30) the
force generated by the extending hydraulic cylinder 40 is converted
to a torque applied to the stair 10 around the stair main pivot
30.
[0046] The force applied by the hydraulic ram 40 may be adjusted so
that when the stairs 10 are in a fully deployed position, an
operator would use the stairs 10. The forces applied through the
hydraulic ram 40 and translated into torque are sufficient to
counteract the weight of the stairs 10 so that the stairs 10 can be
retracted. The torque forces are however not high enough to lift a
person, the stairs 10 may even be stopped from raising by being
held by a person. Once the arc of retraction has progressed so that
the stairs 10 are not within reach of ground personnel the torque
applied increases so that once the stairs 10 are fully retracted
the torque applied to the stairs 10 is sufficient to hold the
stairs 10 in the fully retracted position and prevent them moving
when the earth moving equipment is in operation.
[0047] FIG. 2 shows a typical force profile for a set of stairs 10
operating in the +45.degree. to -90.degree. arc. In this graph the
dotted line shows the torque required to raise the stairs 10 while
the solid line represents the torque applied. It can be seen that
through the arc of +45.degree. to -70.degree. the torque supplied
is in excess of the torque required to raise the stairs 10 by
approximately 10-20 kgm. When the stair 10 are in the fully
retracted position the force required to overcome the tortional
force provided through the retraction mechanism 25 is approximately
80 kgm. These values may be changed by adjusting the force output
of the hydraulic ram 40.
[0048] FIG. 3 shows a typical force profile for a set of stairs
operating in the +60.degree. to -120.degree. arc. In this graph the
dotted line shows the torque required to raise the access stairs 10
while the solid line represents the force applied to the stairs 10.
It can be seen that through the arc of +60.degree. to -60.degree.
the torque supplied in excess of the torque required is
approximately 5 kgm. When the stairs 10 is in the fully retracted
position the force required to overcome the hydraulic force is
substantially more.
[0049] In general the retraction mechanism 25 is set up so that
with a constant output from a hydraulic ram 40 the torsion forces
applied to the stairs 10 exceed the forces required to lift the
stairs 10 for approximately 2/3 of the arc. In the last third of
the arc approaching the fully retracted position the induced torque
force increases so that the stairs 10 are firmly held in the
retracted position and doesn't move excessively while the equipment
is in operation.
[0050] Examples of the retraction mechanism 25 are given in Table
1.
TABLE-US-00001 TABLE 1 Dimension Dimension Description 45.degree.
C. to 90.degree. C. 60.degree. C.-120.degree. C. Stair main pivot
30 to extreme end 2000 mm 700 mm (not shown) Hydraulic Ram Offset
100 100 mm 200 mm Hydraulic Ram mounting bracket 50 1030 mm 550 mm
to stair main pivot 30 Ram stair linkage 55 (pivot centre 255 mm
150 mm to pivot centre) Ram body linkage 57 (pivot centre 220 mm
150 mm to pivot centre) Distance from stair pivot 56 to 160 mm 50
mm main pivot 30 Stair main pivot to body pivot 60 200 mm 65 mm
[0051] The control for the hydraulic ram 40 of the retraction
mechanism 25 may be operated through the pilot circuit for the park
brakes on rubber tyred equipment or the pilot circuit for the
controls on tracked equipment. In large earth moving equipment the
park brakes are normally on and hydraulic pressure is used to
release the brakes. Alternately the hydraulic pressure for the
retraction mechanism 25 may be provided by the main hydraulic
system or from a separate hydraulic pump.
[0052] The graph in FIG. 4 depicts excess lift torque for a vehicle
ladder or stairs retracting through 90.degree. e.g. from near
vertical when deployed to near horizontal when fully retracted. The
graph plots Lift torque (kgm) over and above the torque required to
commence lifting the ladder against the degrees of extension of the
ladder. That is, for example, a graph of the difference between the
dotted line and the solid line shown in each of FIGS. 2 and 3.
[0053] In the embodiment shown, excess lift torque is minimal for
initial lift (retraction) (right hand portion of curve) and
thereafter increases once the ladder has retracted sufficiently
that a user or personnel is either not in danger of injury, or the
ladder is considered sufficiently retracted that the user has had
sufficient warning of retraction or the ladder is out of reach.
[0054] It may be appreciated that although ideally the excess lift
torque would be linear or near linear i.e. a straight line prior to
the increase portion of the graph, physical, mechanical and force
characteristics of the system approximate or approach the ideal,
which is sufficient to provide an effective and efficient working
system without requiring over-engineering or more complex
configurations.
[0055] FIG. 5 shows an alternative excess lift torque curve being
for a ladder retracting from 45.degree. angle of extension (from
the horizontal) to -90.degree. retracted (vertical). Again, ideally
the right hand portion of the graph (before the steep sloped
section) would be linear.
[0056] It will be appreciated that the nearer the generated torque
(solid line in FIGS. 2 and 3) is to the required lift torque in the
right hand side of each graph across the range of angles, the less
manual force is required to halt retraction of the ladder. Also, in
the left hand (steep) section of the graph, the more the solid
(applied force) line deviates away from and above the dotted line,
the greater the force (torque) applied, and the greater the holding
force can be when the ladder is fully retracted. Thus, for the
first approximately two thirds of the retraction process, the
difference between required and applied torque can be minimal,
though applied should not be less than the required torque, the
easier a person can manually stopped retraction (lift) of the
ladder. However, once the ladder has approximately one third
retraction travel to go, lift force (torque) can be significantly
increased, thus speeding up retraction and also providing
sufficient force to maintain the ladder retracted without needing
additional restraining means such as a locking pin mechanism
(though such can be provided if required).
[0057] FIGS. 6a to 6d show a series of steps in the retraction
process. FIG. 6a shows the steps 101 fully extended (approx
45.degree. from horizontal). The upper end 102 would normally be
mounted to a vehicle (not shown). The steps are pivoted to a
retracted position, with deployment being the reverse of
retraction, though if required, the force curve for deployment may
differ from the force curve for retraction. FIG. 6b shows the steps
approximately one third through the retraction process. The lower
end 103 is almost horizontal with the upper end 102. It will be
appreciated that the steps or ladders etc. may take various forms
and arrangements e.g. pivoted in the middle so as to also collapse
to a shorter retracted form. Also the steps or ladders may retract
sideways e.g. pivot sideways. However, the force curve nature of
retraction according to the present invention remains the same.
[0058] Lifting force is provided via an actuating cylinder 104
applying force between a linkage at the upper end of the steps and
a connection 105 approximately halfway down the steps. It will be
appreciated that the arrangement of actuators and linkages may vary
depending on the form and application of the steps, though the
present invention remains unchanged.
[0059] FIG. 6c shows the steps at approximately two thirds
retracted. Consequently, the steps are, in this embodiment,
considered sufficiently retracted as to be generally out of reach
of personnel on the ground or that personnel on the vehicle/steps
have had sufficient time (warning) of retraction of the steps and
therefore are deemed either clear of the steps or have had
sufficient time to apply force during the initial retraction phase
to halt retraction or to manually cause the steps to re-deploy by
overcoming the applied lift torque.
[0060] FIG. 6d shows the steps fully (vertically) retracted.
Between phases 6c and 6d, torque applied to the steps increases,
thereby diverging the applied lift torque curve away from the
required lift torque curve. Force applied at the fully retracted
position is sufficient to prevent or mitigate ladder/step bounce,
thereby reducing risk of damage, injury or vehicle failure (e.g.,
due to bounce causing a proximity switch to inadvertently
operate).
[0061] While the method and apparatus has been explained by
illustrative examples it will be appreciated by those skilled in
the art that varying embodiments and applications are within the
teaching and scope of the present invention. The examples presented
herein are by way of example and should not be construed as
limiting the scope of the present invention.
* * * * *