U.S. patent application number 13/545299 was filed with the patent office on 2013-07-11 for latch for a fold out ramp.
This patent application is currently assigned to LIFT-U, DIVISION OF HOGAN MFG., INC.. The applicant listed for this patent is David Johnson, Donald Morris. Invention is credited to David Johnson, Donald Morris.
Application Number | 20130174359 13/545299 |
Document ID | / |
Family ID | 39938496 |
Filed Date | 2013-07-11 |
United States Patent
Application |
20130174359 |
Kind Code |
A1 |
Morris; Donald ; et
al. |
July 11, 2013 |
LATCH FOR A FOLD OUT RAMP
Abstract
A latch assembly is suitable for a ramp assembly, the ramp
assembly having a ramp portion coupled to a fixed portion so that
the ramp portion reciprocates between a stowed position and a
deployed position. The latch assembly includes a pin associated
with the ramp portion. The latch assembly further includes a latch
fitting rotatably coupled to the fixed portion of the ramp
assembly. The latch fitting has a hook portion and a tang. The hook
portion selectively engages the pin when the ramp assembly is in
the stowed position. The tang selectively provides a lifting force
to the ramp portion.
Inventors: |
Morris; Donald; (Littleton,
CO) ; Johnson; David; (Modesto, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Morris; Donald
Johnson; David |
Littleton
Modesto |
CO
CA |
US
US |
|
|
Assignee: |
LIFT-U, DIVISION OF HOGAN MFG.,
INC.
Escalon
CA
|
Family ID: |
39938496 |
Appl. No.: |
13/545299 |
Filed: |
July 10, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13081417 |
Apr 6, 2011 |
8234737 |
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13545299 |
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12695943 |
Jan 28, 2010 |
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13081417 |
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12114647 |
May 2, 2008 |
7681272 |
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12695943 |
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60944413 |
Jun 15, 2007 |
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60916238 |
May 4, 2007 |
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Current U.S.
Class: |
14/71.1 |
Current CPC
Class: |
B60R 3/02 20130101; A61G
3/067 20161101; A61G 3/061 20130101; Y10T 74/18832 20150115; Y10T
403/32254 20150115; B60P 1/433 20130101; E01D 19/00 20130101; Y10S
414/134 20130101 |
Class at
Publication: |
14/71.1 |
International
Class: |
E01D 19/00 20060101
E01D019/00; B60P 1/43 20060101 B60P001/43 |
Claims
1. A latch assembly for a ramp assembly, the ramp assembly
comprising a ramp portion coupled to a fixed portion to reciprocate
between a stowed position and a deployed position, the latch
assembly comprising: (a) a pin associated with the ramp portion;
and (b) a latch fitting rotatably coupled to the fixed portion of
the ramp assembly, the latch fitting comprising: (i) a hook portion
selectively engaging the pin when the ramp assembly is in the
stowed position; and (ii) a tang selectively providing a lifting
force to the ramp portion.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 13/081,417, filed on Apr. 6, 2011, which is a
continuation of U.S. patent application Ser. No. 12/695,943, filed
on Jan. 28, 2010, which is a continuation of U.S. patent
application Ser. No. 12/114,647, filed on May 2, 2008, which issued
as U.S. Pat. No. 7,681,272 on Mar. 23, 2010, and which claims the
benefit of U.S. Provisional Application No. 60/944,413, filed on
Jun. 15, 2007, and U.S. Provisional Application No. 60/916,238,
filed on May 4, 2007, the disclosures of which are expressly
incorporated by reference.
TECHNICAL FIELD
[0002] The present disclosure relates generally to wheelchair lifts
and, more particularly, to fold out ramps for vehicles.
BACKGROUND
[0003] The Americans with Disabilities Act (ADA) requires the
removal of physical obstacles to those who are physically
challenged. The stated objective of this legislation has increased
public awareness and concern over the requirements of the
physically challenged. Consequentially, there has been more
emphasis in providing systems that assist such a person to access a
motor vehicle, such as a bus or minivan.
[0004] A common manner of providing the physically challenged with
access to motor vehicles is a ramp. Various ramp operating systems
for motor vehicles are known in the art. Some slide out from
underneath the floor of the vehicle and tilt down. Others are
stowed in a vertical position and are pivoted about a hinge, while
still others are supported by booms and cable assemblies. The
present invention is generally directed to a "fold out" type of
ramp. Such a ramp is normally stowed in a horizontal position
within a recess in the vehicle floor, and is pivoted upward and
outward to a downward-sloping extended position. In the extended
position, the ramp is adjustable to varying curb heights.
[0005] Fold out ramps on vehicles confront a variety of technical
problems. Longer ramps are desirable because the resulting slope is
lower and more accessible by wheelchair-bound passengers. Longer
ramps are, however, heavier and require more torque about the pivot
axis to be reciprocated between deployed and stowed positions. To
satisfy this torque requirement, such fold out ramps use large
electric motors, pneumatic devices, or hydraulic actuators to
deploy and stow the ramp. Many of such systems cannot be moved
manually in the event of failure of the power source unless the
drive mechanism is first disengaged. Some existing fold out ramps
can be deployed or stowed manually, but they are difficult to
operate because one must first overcome the resistance of the drive
mechanism. Moreover, dirt and debris often enter an interior
portion of the ramp, causing premature wear and failure. Further,
fold out ramps require a depression (or pocket) in the vehicle's
vestibule floor in which to store the retracted/stowed ramp. When
the ramp is deployed, the aforementioned depression presents an
obstacle for wheelchair passengers as they transition from the ramp
to the vestibule, and on into the vehicle.
[0006] As noted above, many existing fold out ramps are equipped
with hydraulic, electric, or pneumatic actuating devices. Such
devices are obtrusive and make access to and from a vehicle
difficult when the ramp is stowed. Moreover, many of such fold out
ramps have no energy storage capabilities to aid the lifting of the
ramp, which would preserve the life of the drive motor or even
allow a smaller drive to be employed. Finally, operating systems
for such fold out ramps must have large power sources to overcome
the moment placed on the hinge by the necessarily long moment arm
of the fold out ramp.
SUMMARY
[0007] An exemplary embodiment of a described latch assembly is
suitable for a ramp assembly having a ramp portion coupled to a
fixed portion so that the ramp portion reciprocates between a
stowed position and a deployed position. The latch assembly
includes a pin associated with the ramp portion. The latch assembly
further includes a latch fitting rotatably coupled to the fixed
portion of the ramp assembly. The latch fitting has a hook portion
and a tang. The hook portion selectively engages the pin when the
ramp portion is in the stowed position. The tang selectively
applies a lifting force to the ramp portion.
[0008] This summary is provided to introduce a selection of
concepts in a simplified form that are further described below in
the Detailed Description. This summary is not intended to identify
key features of the claimed subject matter, nor is it intended to
be used as an aid in determining the scope of the claimed subject
matter.
DESCRIPTION OF THE DRAWINGS
[0009] The foregoing aspects and many of the attendant advantages
of this invention will become more readily appreciated by reference
to the following detailed description, when taken in conjunction
with the accompanying drawings, wherein:
[0010] FIG. 1 is an isometric view of an exemplary embodiment of a
ramp assembly, with an ramp portion in the stowed position;
[0011] FIG. 2 is an isometric view of the ramp assembly shown in
FIG. 1, with the ramp portion in a deployed position;
[0012] FIG. 3 is an isometric partial cutaway view of the ramp
assembly shown in FIG. 1, with the ramp portion in a position
between the stowed position and a deployed position;
[0013] FIG. 4 is an isometric, partial cut-away view of an outboard
support of a movable floor of the ramp assembly shown in FIG.
3;
[0014] FIG. 5 is an isometric, partial cut-away view of an inboard
support of the movable floor of the ramp assembly shown in FIG.
3;
[0015] FIG. 6 is a partial cross-sectional side view of the
outboard support of the movable floor of the ramp assembly shown in
FIG. 4, with the ramp portion in the stowed position;
[0016] FIG. 7 is a partial cross-sectional side view of the
outboard support of the movable floor of the ramp assembly shown in
FIG. 4, with the ramp portion positioned between the stowed
position and a deployed position;
[0017] FIG. 8 is a partial cross-sectional side view of the
outboard support of the movable floor of the ramp assembly shown in
FIG. 4, with the ramp portion in a deployed position;
[0018] FIG. 9 is a partial cross-sectional side view of the inboard
support of the movable floor of the ramp assembly shown in FIG. 5,
with the ramp portion in the stowed position;
[0019] FIG. 10 is a partial cross-sectional side view of the
inboard support of the movable floor of the ramp assembly shown in
FIG. 5, with the ramp portion positioned between the stowed
position and a deployed position;
[0020] FIG. 11 is a partial cross-sectional side view of the
inboard support of the movable floor of the ramp assembly shown in
FIG. 5, with the ramp portion in a deployed position;
[0021] FIG. 12 is an isometric, partial cut-away view of the ramp
assembly shown in FIG. 1, with the ramp assembly in a deployed
position;
[0022] FIG. 13 is a partial side view of the ramp assembly shown in
FIG. 1, with the ramp portion in a neutral position;
[0023] FIG. 14 is a partial side view of the ramp assembly shown in
FIG. 1, with the ramp portion positioned between a neutral position
and the stowed position;
[0024] FIG. 15 is a partial side view of the ramp assembly shown in
FIG. 1, with the ramp portion positioned between a neutral position
and a deployed position;
[0025] FIG. 16 is a chart showing a moment provided by a
counterbalance of the ramp assembly of FIG. 13;
[0026] FIG. 17 is a partial cross-sectional view of a closeout
assembly of the ramp assembly shown in FIG. 1, with the ramp
portion in the stowed position;
[0027] FIG. 18 is a partial cross-sectional view of the closeout
assembly shown in FIG. 17, with the ramp portion positioned between
the stowed position and a deployed position;
[0028] FIG. 19 is a partial cross-sectional view of the closeout
assembly shown in FIG. 17, with the ramp portion in a deployed
position;
[0029] FIG. 20 is an isometric, partial cut-away view of the ramp
assembly shown in
[0030] FIG. 1, with the ramp assembly in a position between the
stowed position and a deployed position;
[0031] FIG. 21 is a partial cross-sectional view of a latch
assembly of the ramp assembly shown in FIG. 20, with the ramp
portion in the stowed position;
[0032] FIG. 22 is a partial cross-sectional view of the latch
assembly of FIG. 21 during a powered unlatch operation;
[0033] FIG. 23 is a partial cross-sectional view of the latch
assembly of FIG. 21 during a first phase of a manual unlatch
operation; and
[0034] FIG. 24 is a partial cross-sectional view of the latch
assembly of FIG. 21 during a second phase of a manual unlatch
operation.
DETAILED DESCRIPTION
[0035] Exemplary embodiments of the present invention will now be
described with reference to the accompanying drawings where like
numerals correspond to like elements. Exemplary embodiments of the
present invention are directed to ramp assemblies, and more
specifically, to wheelchair ramp assemblies. In particular, several
embodiments of the present invention are directed to wheelchair
ramp assemblies suitable for use in buses, vans, etc. Several
embodiments of the present invention are directed to compact ramp
assemblies for a vehicle that when stowed, occupy a small amount of
space within the vehicle floor, yet deploy to a length that
effectively reduces the ramp slope encountered by the mobility
impaired, thus facilitating greater independence and safety for
wheelchair-bound passengers.
[0036] The following discussion proceeds with reference to examples
of wheelchair ramp assemblies for use in vehicles having a floor,
such as a bus, van, etc. While the examples provided herein have
been described with reference to their association with vehicles,
it will be apparent to one skilled in the art that this is done for
illustrative purposes and should not be construed as limiting the
scope of the invention, as claimed. Thus, it will be apparent to
one skilled in the art that aspects of the present invention may be
employed with other ramp assemblies used in stationary
installations, such as residential buildings and the like.
[0037] The following detailed description may use illustrative
terms such as vertical, horizontal, front, rear, inboard, outboard,
proximal, distal, etc. However, these terms are descriptive in
nature and should not be construed as limiting. Further, it will be
appreciated that embodiments of the present invention may employ
any combination of features described herein.
[0038] Fold Out Ramp Assembly
[0039] FIGS. 1 and 2 illustrate one embodiment of a fold out ramp
assembly 20 (hereinafter "ramp assembly 20"). The ramp assembly 20
includes a frame 30, a drive assembly 80, an ramp portion 60, an
intermediate panel assembly 70, a movable floor 40, and a
counterbalance assembly 100. The frame 30 of the ramp assembly 20
is adapted to be mounted to a vehicle (not shown) having a floor,
such as a bus or a van. The ramp assembly 20 is reciprocal between
the stowed position, as shown in FIG. 1, and a deployed position,
as shown in FIG. 2.
[0040] Although the illustrated embodiments of the ramp assembly 20
include a frame 30, other embodiments are contemplated in which the
ramp assembly 20 does not include a frame 30. When such embodiments
are installed in vehicles, the ramp assembly 20 components are
attached directly to the structure of the vehicle or to a suitable
structure within the vehicle, thus making a frame 30 unnecessary.
Similarly, when such embodiments are installed in stationary
installations, such as residential buildings and the like, the ramp
assembly 20 components are attached to the structure of the
building or any other suitable structure within the building.
Accordingly, embodiments of the described ramp assembly 20 that do
not include a frame, should be considered within the scope of the
present disclosure.
[0041] Referring to FIGS. 1 and 2, the ramp portion 60 has a first
end 61 and a second end 62. When the ramp portion 60 is in the
stowed position, the first end 61 of the ramp portion 60 is
outboard of the second end 62 of the ramp portion 60. As the ramp
portion 60 moves from the stowed position to a deployed position,
the ramp portion 60 rotates about the first end 61 of the ramp
portion 60 until the second end 62 of the ramp portion 60 is
outboard of the first end 61 of the ramp portion 60.
[0042] As best shown in FIG. 1, when the ramp assembly 20 is in the
stowed position, the ramp portion 60 and the movable floor 40 are
located such that the ramp portion 60 is positioned over the
movable floor 40, and the lower surface 66 of the ramp portion 60
is substantially parallel with the floor (not shown) of the
vehicle. In the deployed position, the ramp portion 60 extends in
an outboard direction and contacts a surface 22, such as a curb or
road side.
[0043] Referring now to FIG. 2, the ramp portion 60 is pivotally
connected at the first end 61 to the frame 30. In addition, the
first end 61 of the ramp portion 60 is hingedly coupled to the
outboard end 74 of the intermediate panel assembly 70. The ramp
portion 60 includes a panel 63, which is constructed from
well-known materials. The ramp portion 60 further includes side
curbs 68. The side curbs 68 extend upwardly from the forward and
rear sides of the panel 63. Each side curb 68 enhances the
structural strength of the ramp portion 60 and provides edge guards
for the sides of the ramp portion 60, thereby increasing the safety
of the ramp assembly 20. The second end 62 of the ramp portion 60
includes a tapered nose portion 64. The tapered nose portion 64
provides a smooth transition between the panel 63 and the curb or
sidewalk when the ramp assembly 20 is in a deployed position.
[0044] The movable floor 40 includes an inboard portion 42 fixedly
located at an angle relative to a sloping outboard portion 44. When
the ramp portion 60 is stowed, the movable floor 40 is disposed
within the frame 30 and below the ramp portion 60 in a lowered
position as best shown in FIGS. 6 and 9. Referring to FIGS. 6-11,
as the ramp portion 60 is deployed, the outboard portion 44 of the
movable floor 40 translates inboard and outboard in a substantially
horizontal direction, while the inboard portion 42 travels upward
in a substantially arcuate, clockwise path as viewed in FIGS.
9-11.
[0045] Referring back to FIG. 2, a gap exists between the first end
61 of the ramp portion 60 and the outboard end of the movable floor
40. The intermediate panel assembly 70 bridges this gap and
provides a transition surface between the ramp portion 60 and the
movable floor 40. As best shown in FIGS. 3 and 4, the intermediate
panel assembly 70 includes a panel 78 supported at the forward and
rear sides by a pair of side supports 76.
[0046] The outboard end 74 of the intermediate panel assembly 70 is
hingedly coupled to the first end 61 of the ramp portion 60 about a
first hinge axis 34. As best shown in FIGS. 6-8, hinge pins 38 are
located at the forward and rear sides of the first end 61 of the
ramp portion 60 to hingedly attach the first end 61 of the ramp
portion 60 to the side support 76 of the intermediate panel
assembly 70. The hinge pins 38 are positioned so that the hinge
axis 34 is substantially parallel to, but offset from, the axis of
rotation of the outboard sprockets 88. As a result, the hinge axis
34, and thus the outboard end 74 of the intermediate panel assembly
70, moves in an arcuate path around the centerline of the outboard
sprocket 88 when the ramp portion 60 moves between the stowed
position and a deployed position.
[0047] The inboard end 72 of the intermediate panel assembly 70 is
hingedly coupled to the outboard end of the movable floor 40 about
a second hinge axis 36. As best shown in FIGS. 6-8, hinge pins 56
are located along the second hinge axis 36 at the forward and rear
sides of the outboard end of the movable floor 40 to hingedly
attach the outboard end of the movable floor 40 to the side support
76 of the intermediate panel assembly 70. The second hinge axis 36
is substantially parallel to, but offset from, the axis of rotation
of the outboard sprockets 88.
[0048] When the ramp portion 60 is in a deployed position, the
outboard portion 44 of the movable floor 40 extends from the
inboard portion 42 of the movable floor 40 in an outboard and
downward direction to the outboard edge of the movable floor 40 so
that the outboard portion 44 of the movable floor 40 has a slope
approximately equal to the slope of the ramp portion 60. The
outboard portion 44 of the movable floor 40 is also approximately
parallel to the ramp portion 60 so that the intermediate panel
assembly 70 also has a slope similar to the outboard portion 44 of
the movable floor 40 and to the ramp portion 60. It should be
appreciated that some variations in the slopes of the ramp portion
60, the intermediate panel assembly 70, and the outboard portion 44
of the movable floor 40 may result from different distances between
the floor of the vehicle and the curb or street surfaces.
[0049] As a result of the above-described configuration, the
outboard portion 44 of the movable floor 40 and the intermediate
panel assembly 70 effectively increase the overall length of the
sloped portion of the deployed ramp. Consequently, a more gradual
slope is achieved without increasing the length of the ramp portion
60. Because the length of the ramp portion 60 is not increased, the
torque required from the drive motor 82 to reciprocate the ramp
portion 60 between the stowed position and a deployed position is
not increased.
[0050] The drive assembly 80 actuates the ramp portion 60. As a
result, the ramp portion 60 reciprocates between the stowed
position and a deployed position. A forward portion of the drive
assembly is located on the forward side of the frame 30. A rear
portion of the drive assembly 80 is similarly located on the rear
side of the frame 30, wherein each element of the forward portion
of the drive assembly 80 corresponds to a similar element of the
rear portion of the drive assembly 80. For the sake of clarity, the
forward portion of the drive assembly 80 is described herein with
the understanding that unless otherwise indicated, each element of
the forward portion has a corresponding element on the rear portion
of the drive assembly 80.
[0051] Referring to the embodiment shown in FIGS. 1 and 2, the
drive assembly 80 includes an inboard sprocket 86 that is rotatably
coupled to the inboard end of the forward side of the frame 30. The
inboard sprocket 86 is oriented to have an axis of rotation that
extends in the forward/rearward direction. The drive assembly 80
also includes an outboard sprocket 88 rotatably coupled to the
outboard end of the forward side of the frame 30. The outboard
sprocket 88 is oriented to have an axis of rotation that is
substantially parallel to the axis of rotation of the inboard
sprocket 86. A drive chain 92 forms an endless loop that engages
the teeth of the outboard sprocket 88 and the teeth of the inboard
sprocket 86. Movement of the drive chain 92 along the path of the
drive chain 92 rotates the inboard sprocket 86 and the outboard
sprocket 88.
[0052] The drive assembly 80 further includes drive sprocket 84
rotatably coupled to the forward side of the frame 30 intermediate
to the inboard sprocket 86 and outboard sprocket 88. The drive
sprocket 84 is oriented to have an axis of rotation substantially
parallel to the axes of rotation of the inboard sprocket 86 and
outboard sprocket 88. As shown in FIG. 12, a drive shaft 83 is
coupled to the drive sprocket 84 for connecting the drive sprocket
84 to a motor 82, wherein the drive shaft 83 is operatively coupled
to the motor 82 by a well-known transmission means 85. The motor 82
is selectively operated to rotate the drive sprocket 84, thereby
driving the inboard sprocket 86 and the outboard sprocket 88 via
the drive chain 92. In one embodiment, a single motor 82 drives the
drive sprocket 84 of the forward portion of the drive assembly 80
and also the drive sprocket 84 of the rear portion of the drive
assembly 80. In another embodiment, each drive sprocket 84 is
driven by a separate motor 82.
[0053] One or more idler sprockets 90 may be included in the drive
assembly 80. The optional idler sprockets 90 engage the drive chain
92 to redirect the drive chain 92 along a predetermined path. The
drive chain 92 includes a turnbuckle 98 that is selectively
adjustable to increase or decrease the length of the drive chain 92
in order to adjust the tension of the drive chain 92.
[0054] As illustrated in FIGS. 6-11, the inboard sprockets 86 and
outboard sprockets 88 of the drive assembly 80 rotate cooperatively
to reciprocate the ramp assembly 20 between the stowed position and
a deployed position. More specifically, the outboard sprockets 88
rotate to reciprocate the ramp portion 60 between the stowed
position and a deployed position. At the same time, the inboard
sprockets 86 and outboard sprockets 88 cooperate to arcuately raise
and lower, and horizontally translate the movable floor 40 as the
ramp portion 60 reciprocates between the stowed position and a
deployed position.
[0055] Actuation of the Ramp Portion
[0056] FIGS. 6-8 illustrate the outboard sprocket 88 as it drives
the ramp portion 60 from the stowed position (FIG. 6), through an
intermediate position (FIG. 7), to a deployed position (FIG. 8).
Referring to FIG. 6, a portion of the outboard sprocket 88 extends
through the frame 30 to act as a ramp support element. The ramp
portion 60 is fixedly attached to a portion of the outboard
sprocket 88 that extends axially through the frame 30 into the
interior portion of the frame 30. The lower surface 66 of the ramp
portion 60, which faces up when the ramp assembly 20 is in the
stowed position, is offset from the axis of rotation of the
outboard sprocket 88 so that the lower surface 66 is generally
horizontal and coplanar with the floor of the vehicle when the ramp
assembly 20 is in the stowed position.
[0057] To move the ramp portion 60 from the stowed position to a
deployed position, the outboard sprocket 88 is driven by the drive
assembly 80 to rotate in a counterclockwise direction as viewed in
FIG. 7 (i.e., the direction of the arrow shown in FIG. 7). The ramp
portion 60 rotates with the outboard sprocket 88 until the tapered
nose 64 of the ramp portion 60 contacts a surface 22 of the road or
sidewalk, at which point the ramp portion 60 is in a deployed
position.
[0058] Conversely, to move the ramp portion 60 from a deployed
position to the stowed position, the drive assembly 80 rotates the
outboard sprocket 88 in a clockwise direction as viewed in FIG. 7
(i.e., the direction opposite the arrow shown in FIG. 7). The ramp
portion 60 rotates with the outboard sprocket 88 until the lower
surface 66 of the ramp portion 60 is generally horizontal and
coplanar with the floor of the vehicle, at which point the ramp
portion 60 is in the stowed position. In the stowed position, the
ramp portion is supported at its edges by the frame 30 or the
vehicle floor. By selectively operating the motor 82 of the drive
assembly 80, the ramp portion 60 is reciprocated between the stowed
position and a deployed position.
[0059] Actuation of the Movable Floor
[0060] i. Outboard End
[0061] As best shown in FIGS. 6-8, the outboard end of the movable
floor 40 travels along a generally horizontal path in the
inboard/outboard direction as the outboard sprocket 88 rotates to
move the ramp portion 60 between the stowed position and a deployed
position. A roller bearing 52 is rotatably mounted to the frame 30
and positioned within the frame 30 to contact a bearing surface 54
located on the outboard portion 44 of the movable floor 40. The
bearing surface 54 is located on a lower surface of the movable
floor 40 so that the roller bearing 52 contacts the bearing surface
54 from below, thereby providing support to the outboard end of the
movable floor 40 in a vertical direction.
[0062] As shown in FIG. 6, when the ramp portion 60 is in the
stowed position, the hinge pin 38 connecting the ramp portion 60 to
the intermediate panel assembly 70 is located above the axis of
rotation of the outboard sprocket 88. Referring to FIGS. 7 and 8,
when the outboard sprocket 88 rotates, the hinge axis 34 of the
hinged connection between the ramp portion 60 and the intermediate
panel assembly 70 moves in an arcuate path around the axis of
rotation of the outboard sprocket 88. This motion drives the
outboard end 74 of the intermediate panel assembly 70, which, in
turn, drives the inboard end 72 of the intermediate panel assembly
70. The movement of the inboard end 72 of the intermediate panel
assembly 70 drives the outboard portion 44 of the movable floor 40,
which is supported in a vertical direction by the roller bearing
52.
[0063] When the ramp portion 60 is moved from a deployed position
to the stowed position, the hinge pin 38 moves in a clockwise
direction, driving the intermediate panel assembly 70 and the
outboard portion 44 of the movable floor 40 in the reverse
direction of the path traveled when the ramp portion 60 is being
deployed.
[0064] ii. Inboard End
[0065] FIGS. 9-11 illustrate the inboard sprocket 86 as it raises
the inboard end of the movable floor 40 as the ramp portion 60
moves from the stowed position (FIG. 9), through an intermediate
position (FIG. 10), to a deployed position (FIG. 11). Referring to
FIG. 9, a first end of a link 94 is fixedly coupled to the inboard
sprocket 86. The link 94 extends radially from the inboard sprocket
86 so that the second end of the link 94 revolves around the axis
of rotation of the inboard sprocket 86 as the inboard sprocket 86
is rotated by the drive assembly 80. A follower bearing 96 is
rotatably coupled to the second end of the link 94 so that the axis
of rotation of the follower bearing 96 is approximately parallel to
the axis of rotation of the inboard sprocket 86. The follower
bearing 96 travels in an arcuate path around the axis of rotation
of the inboard sprocket 86 when the drive assembly 80 drives the
inboard sprocket 86. The inboard sprocket 86, the link 94, and the
follower bearing 96 cooperate to function as a reciprocating
mechanism to reciprocate the inboard end of the movable floor 40
between a raised position and a stowed position.
[0066] A side support 46 extends along the lower edge of the
movable floor 40 from the inboard end of the movable floor 40 to
the outboard end of the movable floor 40. The side support 46
includes a protrusion that extends from the inboard portion of the
side support 46 in an outboard and downward direction to form a
C-shaped catcher 48. The catcher 48 opens toward the outboard end
of the ramp assembly 20. The lower portion of the side support that
is located outboard of the catcher 48 includes a bearing surface
50.
[0067] As shown in FIG. 9, when the ramp portion 60 is in the
stowed position, the link 94 extends downward from the inboard
sprocket 86. As a result, the follower bearing 96 is positioned
below the axis of rotation of the inboard sprocket 86. The follower
bearing 96 engages the bearing surface 50 of the side support 46,
thereby supporting the inboard end of the movable floor 40. If
external forces tend to raise the inboard end of the movable floor
40, the follower bearing 96 engages the catcher 48, thereby
preventing the side support 46, and therefore the movable floor 40,
from moving in an upward direction. The catcher 48 also restrains
the movable floor 40 to reduce unwanted noise and vibration when
the vehicle is in motion.
[0068] Referring to FIG. 10, when the ramp portion 60 moves from
the stowed position to a deployed position, the inboard sprocket 86
rotates in a clockwise direction. As the follower bearing 96
travels along an arcuate path as a result of the motion of the
inboard sprocket 86, the follower bearing 96 maintains contact with
the bearing surface 50. Thus, the follower bearing 96 provides
continuous support to the inboard end of the movable floor 40 as
the follower bearing 96 travels along an arcuate path, thereby
raising the inboard end of the movable floor 40.
[0069] FIG. 11 shows the inboard end of the movable floor 40 when
ramp portion 60 is in a deployed position. The follower bearing 96
is generally positioned above the axis of rotation of the inboard
sprocket 86 and is disposed within the catcher 48. The follower
bearing 96 supports the side support 46 of the movable floor 40 so
that the upper surface of the movable floor 40 is generally
horizontal and coplanar with the floor of the vehicle.
[0070] When the ramp portion 60 is moved from a deployed position
to the stowed position, the inboard sprocket 86 rotates in a
counterclockwise direction as viewed in FIG. 10 (i.e., the
direction opposite the arrows shown in FIG. 10), and the follower
bearing 96 travels in a downward arcuate path. The inboard end of
the movable floor 40, which is supported by the follower bearing
96, travels downward with the follower bearing 96 until the ramp
portion 60 is in the stowed position. When the ramp portion 60 is
in the stowed position, the inboard end of the movable floor 40 is
disposed within the frame 30 in a lowered position.
[0071] As previously discussed, the drive chain 92 coordinates the
rotation of the inboard sprocket 86 and the outboard sprocket 88.
Accordingly, the inboard sprocket 86 and the outboard sprocket 88
cooperate to control the position of the movable floor 40.
[0072] When the ramp portion 60 is in a deployed position, the
sloped portion of the ramp assembly 20 has a slope defined as ratio
of the height (rise) of the sloped portion to the horizontal length
(run) of the sloped portion. To provide a slope that is gradual
enough to allow safe ingress to and egress from the vehicle by a
person in a wheelchair, the ratio of rise to run is generally no
greater than 1:4. Smaller ratios, such as 1:5, 1:6, and 1:7 are
preferable from a safety standpoint, but given vehicle floor height
constraints, smaller ratios generally require longer ramps, which
result in larger actuation motors and more space required within
the vehicle to stow the ramps. Although embodiments are not limited
to any particular ratio, a ratio of 1:6 has been found to provide a
balance between the increased safety of a more gradual slope and
the design constraints inherent in a longer ramp.
[0073] Counterbalance Assembly
[0074] FIG. 13 illustrates the ramp portion 60 in a position
between the stowed position and a deployed position. In the
illustrated position, the ramp portion 60 forms an angle of
approximately 90.degree. with the frame 30. The center of gravity
(CG) of the ramp portion 60 is located approximately over the axis
of rotation of the outboard sprocket 88 when the ramp portion is in
this "neutral" position. In the illustrated embodiments, the weight
of the ramp is idealized as a point load W applied at the CG of the
ramp portion 60. When the ramp portion 60 is in the neutral
position, the weight of the ramp portion 60 does not impart a
moment M.sub.W about the axis of rotation of the outboard sprocket
88. FIG. 14 shows the ramp portion 60 at a position between the
neutral position and the stowed position. When the ramp portion is
so positioned, the CG of the ramp portion 60 is located inboard of
the axis of rotation of the outboard sprocket 88. Accordingly, the
weight W of the ramp portion 60 imparts moment M.sub.W about the
axis of rotation of the outboard sprocket 88, wherein the moment
M.sub.W tends to move the ramp portion 60 toward the stowed
position. FIG. 15 shows the ramp portion 60 at a position between
the neutral position and a deployed position. In this position, the
CG of the ramp portion 60 is located outboard of the axis of
rotation of the outboard sprocket 88. As a result, the weight W of
the ramp portion 60 imparts moment M.sub.W about the axis of
rotation of the outboard sprocket 88, wherein the moment M.sub.W
tends to move the ramp portion toward a deployed position. Although
the neutral position is illustrated as a position wherein the ramp
portion 60 is positioned an angle of approximately 90.degree. from
the frame 30, it should be understood that the position of the CG
of the ramp portion 60 can vary, resulting in a neutral position
wherein the angle of the ramp portion to the frame 30 is greater
than or less than 90.degree..
[0075] As shown in FIGS. 13-15, the ramp assembly 20 may include a
counterbalance assembly 100 to counteract the moment M.sub.W
imparted about the axis of rotation of the outboard sprocket 88 by
the weight of the ramp. The counterbalance assembly provides a
moment M.sub.F that opposes the moment M.sub.W produced by the ramp
portion 60. Because the moment M.sub.W is counteracted by the
moment M.sub.F provided by the counterbalance assembly 100, the
torque output required from the motor 82 of the drive assembly 80
is reduced. The reduced torque requirement allows for the use of a
smaller motor 82.
[0076] In the embodiment illustrated in FIGS. 13-15, the
counterbalance assembly 100 includes an upper spring assembly 102
and a lower spring assembly 122 on each of the forward and rear
sides of the ramp assembly 20, for a total of four spring
assemblies. For the sake of clarity, the upper and lower spring
assemblies 102, 122 located on the forward side of the ramp
assembly 20 are described with the understanding that similar upper
and lower spring assemblies 102, 122 are located on the rear side
of the ramp assembly 20.
[0077] Referring to FIG. 13, the upper and lower spring assemblies
102, 122 are attached in series to segments of the drive chain 92.
More specifically, the outboard end of the upper spring assembly
102 is coupled to the upper end of an outboard chain segment 118,
and the inboard end of the upper spring assembly 102 is coupled to
the upper end of an inboard chain segment 120. The outboard end of
the lower spring assembly 122 is coupled to the lower end of the
outboard chain segment 118, and the inboard end of the lower spring
assembly 122 is coupled to the lower end of the inboard chain
segment 120. In this manner, a drive chain is formed into an
endless loop, wherein the loop comprises the following components
in order: outboard chain segment 118, upper spring assembly 102,
inboard chain segment 120, and lower spring assembly 122.
[0078] The lower spring assembly 122 includes a rigid rod 114
positioned in an inboard/outboard orientation. The outboard end of
the rod 114 is coupled to the lower end of the outboard chain
segment 118 with a pinned connection at 124A. Similarly, the
inboard end of the rod 114 is coupled to the lower end of the
inboard chain segment 120 with a pinned connection at 124B. A
helical compression spring 104 is concentrically arranged with
respect to the rod 114 so that the rod 114 is disposed within the
center of the coils of the spring 104.
[0079] The lower spring assembly 122 further includes a spring
fitting 106A, a cylindrical bushing 108A, and an adjustment nut
112A associated with the outboard end region of the rigid rod 114.
The spring fitting 106A has an aperture with a diameter larger than
the outer diameter of the rod 114, but smaller than the outer
diameter of the compression spring 104. The spring fitting 106A is
slidingly coupled to the outboard end of the rod 114 so that the
rod passes through the aperture of the spring fitting 106A. The
cylindrical bushing 108A (biasing element) is coupled to the rod
114 so that a portion of the rod 114 is disposed within the bore of
the bushing 108A. Thus, the outboard end of the compression spring
104 bears against the inboard surface the spring fitting 106A, and
the outboard surface of the spring fitting 106A bears against the
inboard surface of the cylindrical bushing 108A. The adjustment nut
112A threadedly engages a threaded portion of the outboard end of
the rod 114. The inboard end of the adjustment nut 112A engages the
outboard end of the cylindrical bushing 108A, preventing the
cylindrical bushing 108A, the spring fitting 106A, and the outboard
end of the compression spring 104 from moving in an outboard
direction relative to the rod 114.
[0080] Similar to the outboard end of the rod 114, a spring fitting
106B, a bushing 108B, and an adjustment nut 112B are attached to
the inboard end of the rod 114. That is, the spring fitting 106B is
installed inboard of the compression spring 104, the bushing 108B
(biasing element) is installed inboard of the spring fitting 106B,
and the adjustment nut 112B installed inboard of the bushing
108B.
[0081] Still referring to FIG. 13, the compression spring 104 of
the described lower spring assembly 122 is compressed between the
two spring fittings 106A-B. The combination of the spring fittings
106A-B, bushings 108A-B, and nuts 112A-B prevents the compressed
spring from expanding in either the inboard or outboard direction.
Further, the preload on the compressed spring 104 can be adjusted
by selectively adjusting the distance between the adjustment nuts
112A-B. As the distance between the nuts 112A-B is decreased, the
spring 104 is further compressed, increasing the preload on the
spring 104. Conversely, if the distance between the nuts 112A-B is
increased, the spring 104 expands, and the preload on the spring
104 is decreased.
[0082] The compression spring 104 and spring fittings 106A-B are
disposed between the inboard and outboard end stops 110A-B. Each
end stop 110A-B includes a pair of protrusions to define a channel
therebetween. Each channel is positioned in the direction of the
compression spring and is sized to allow the bushings 108A-B and
adjustment nuts 112A-B to pass therethrough. The spring fittings
106A-B, however, are sized so as not to pass through the channels,
but instead remain disposed between the inboard and outboard end
stops 110A-B.
[0083] The upper spring assembly 102 is identical to the lower
spring assembly 122 with one exception. In the illustrated
embodiment shown in FIGS. 13-15, the inboard end of the rod 114 is
coupled to one end of a turnbuckle 98. The other end of the
turnbuckle 98 is coupled to the upper end of the inboard chain
segment 120. The tension of the drive chain 92 is selectively
adjustable by rotating the turnbuckle 98. Although the turnbuckle
98 is illustrated attached to the inboard end of the upper spring
assembly 102, it should be understood that the turnbuckle can be
located at any position along the path of the drive chain 92 that
does not interfere with the spring assemblies 102, 122 or the
sprockets of the drive assembly 80.
[0084] FIG. 14 shows the ramp assembly 20 with the ramp portion 60
located between a neutral position and the stowed position. As the
ramp portion 60 moves toward the stowed position, the CG of the
ramp portion moves inboard, imparting a moment M.sub.W that tends
to move the ramp portion 60 into the stowed position. Moreover, as
the ramp portion 60 moves further towards the stowed position, the
horizontal distance between the axis of rotation of the ramp
portion 60 and the CG of the ramp portion 60 increases, thus
increasing the magnitude of the moment M.sub.W on the outboard
sprocket 88.
[0085] The moment M.sub.W imparted by the weight W of the ramp
portion 60 is counteracted by compression of the springs 104 of the
upper and lower spring assemblies 102, 122. Referring to FIG. 14,
as the ramp portion 60 moves toward the stowed position, the drive
chain 92 moves in a clockwise direction along its path. With regard
to the upper spring assembly 102, the clockwise motion of the drive
chain 92 drives the outboard adjustment nut 112A, which is
threadedly secured to the rod 114, in an inboard direction. As the
nut 112A moves inboard, it drives the bushing 108A and the spring
fitting 106A inboard, creating a gap 116 between the outboard end
of the spring fitting 106A and the inboard end of the end stop
110A. The inboard end of the spring fitting 106A bears against the
outboard end of the compression spring 104 so that the outboard end
of the compression spring 104 moves inboard with the spring fitting
106A. At the inboard end of the upper spring assembly 102, the
bushing 108A and the adjustment nut 112A move inboard with the
drive chain 92 and the rod 114. The spring fitting 106B, and
therefore the inboard end of the compression spring 104, are
prevented from moving inboard by the inboard end stop 110B.
[0086] As described above, movement of the ramp portion 60 from a
neutral position to the stowed position causes the outboard end of
the upper compression spring 104 to move inboard, while the inboard
end remains fixed against the inboard end stop 110B. The resulting
compression of the spring 104 creates a force that, combined with
the forces created by the other springs, imparts the moment M.sub.F
to resist the moment M.sub.W that results from the weight W of the
ramp portion 60. The resistive force is approximately proportional
to the amount by which the spring 104 is compressed, i.e., the
spring is a linear spring. That is, greater spring compression
results in a greater resistive force. As previously noted, the
moment M.sub.W increases as the ramp portion 60 approaches the
stowed position from a neutral position. The resistive force
supplied by the spring 104 and therefore, the moment M.sub.F
created by the spring resistive force, also increase as the ramp
portion 60 approaches the stowed position. The increase in the
moment M.sub.W is sinusoidal, while the increase in the moment
M.sub.F is linear. As described below in further detail, the
counterbalance assembly 100 can be configured such that M.sub.F
more closely approximates M.sub.W as the ramp reciprocates between
the stowed position and a deployed position.
[0087] The springs 104 of the counterbalance assembly 100 are
preferably selected to minimize the difference between the force
supplied by the springs 104 and the force required to counteract
the moment M.sub.W as the ramp portion 60 reciprocates between a
stowed position and a deployed position. For linear springs, the
spring stiffness can be selected such that the linear increase in
spring resistance is a best fit of the sinusoidal increase of the
moment M.sub.F. As a result, the difference between M.sub.W and
M.sub.F is minimized. In other embodiments, non-linear springs are
used so that the resistance supplied by the spring increases at a
non-linear rate, allowing the spring resistance to match more
closely the force required to resist the moment M.sub.F as the ramp
portion 60 reciprocates between a stowed position and a deployed
position. Non-linear springs are known in the art. For example, a
spring formed with a variable coil pitch will exhibit non-linear
properties. It should be understood that various known spring
configurations providing linear or non-linear reactive force can be
included in the counterbalance assembly 100 without departing from
the spirit and scope of the present invention. In addition,
alternate systems can be used to provide a resistive force, such as
pneumatic systems, hydraulic systems, and other systems known in
the art.
[0088] The lower spring assembly 122 functions in the same manner
as the upper spring assembly 102. As the ramp portion 60 moves from
a neutral position to the stowed position, the inboard spring
fitting 106B moves outboard to compress the spring 104 against the
outboard spring fitting 106A, which is prevented from moving in the
outboard direction by the outboard end stop 110A. The compression
of the spring 104 results in a force that resists the moment
M.sub.W resulting from the weight of the ramp portion 60.
[0089] The resistive forces produced by the upper and lower spring
assemblies 102, 122 act on the drive chain 92 in a direction
opposite to the moment M.sub.W. As the moment M.sub.W shown in FIG.
14 tends to move the drive chain 92 in a clockwise direction, the
resistive forces produced by the upper and lower spring assemblies
102, 122 impart a moment M.sub.F that tends to move the drive chain
in a counterclockwise direction. To the extent that the resistive
forces counteract the moment M.sub.W, the torque required from the
motor 82 to drive the drive assembly 80 is reduced.
[0090] FIG. 15 illustrates the ramp assembly 20 with the ramp
portion 60 located between a neutral position and a deployed
position. The CG (not shown) of the ramp portion 60 is located
outboard of the axis of rotation of the ramp portion 60, creating a
moment M.sub.W that tends to move the ramp portion 60 into the
deployed position. The upper and lower spring assemblies are
compressed in a similar fashion as discussed with respect to FIG.
14, but in an opposite direction. More specifically, as the moment
M.sub.W tends to move the drive chain 92 in a counterclockwise
direction, the upper and lower spring assemblies 102, 122 provide
resistive forces that create a moment M.sub.F that tends to move
the drive chain in a clockwise direction.
[0091] As previously noted, upper and lower spring assemblies 102,
122 are positioned on the forward and rear sides of the ramp
assembly 20. The four spring assemblies cooperate to provide the
moment M.sub.F that resists the moment M.sub.W created when the
ramp is not in a neutral position, with each spring assembly
providing approximately one fourth of the total resistive
force.
[0092] The counterbalance assembly 100 can be configured so that
the difference between the moment M.sub.F and the moment M.sub.W is
minimized. More specifically, the preload in the springs 104, and
the contact between the spring fittings 106A-B and the end stops
110A-B can be controlled so that the moment M.sub.F is not linear,
but instead approximates the sinusoidal increase and decrease of
the moment M.sub.W.
[0093] Referring to FIG. 13, the illustrated counterbalance
assembly 100 includes a lower spring assembly 122, wherein the
inboard and outboard spring fittings 106A-B do not contact the end
stops 110A-B when the ramp portion 60 is in the neutral position.
As a result, a dead space 126 exists between the each spring
fitting 106A-B and its respective end stop 110A-B. As the ramp
portion 60 initially moves from the neutral position toward the
stowed position, the outboard spring fitting 106A moves toward the
outboard end stop 110A, reducing the amount of dead space 126.
After the outboard spring fitting 106A contacts the outboard end
stop 110A, the lower spring assembly begins to provide a resistive
force. Similarly, when the ramp portion 60 moves from the neutral
position toward a deployed position, the inboard spring fitting
106B travels toward the inboard end stop 110B. Only after the dead
space 126 has been eliminated, i.e. when the inboard spring fitting
106B contacts the inboard end stop 110B, does the lower spring
assembly 122 provide a resistive force.
[0094] The preload in the spring assemblies 102, 122 can be
adjusted by selectively adjusting the nuts 112A-B to control
compression of the springs 104. However, adjusting the preload in
this manner also introduces dead space into the spring assemblies
102, 122. The preload in the spring assemblies 102 and 122 can also
be adjusted independent of the dead space 126. In the illustrated
embodiment, the spring fittings 106A-B are shown as flanged
bushings. By increasing or decreasing the length of the cylindrical
portion of the bushings, the space between the spring fittings, and
thus, the preload on the spring 104 can be controlled independent
of the distance from the bushing flange to its respective end stop
110, which defines the dead space.
[0095] By adjusting the amount of dead space 126 and preload on the
upper and lower spring assemblies 102 and 122, the moment M.sub.F
can be made to more closely approximate the moment M.sub.W produced
by the weight of the ramp. FIG. 16 is a chart illustrating the
moment M.sub.F produced by the exemplary ramp assembly 20
illustrated in FIGS. 13-15 as the ramp assembly 20 reciprocates
between the stowed position and a deployed position. A line
representing the moment M.sub.F that is a linear best fit of the
moment M.sub.W is also shown. The linear best fit represents the
moment M.sub.F produced when the springs 104 have a zero preload,
and no dead space 126 exists at the neutral position.
[0096] The chart shown in FIG. 16 further includes a series of
lines representing an exemplary moment M.sub.F produced when a dead
space 126 exists on the lower spring assembly 122, but not on the
upper spring assembly 102. When the ramp portion 60 is at or near
the neutral position, only the upper spring assembly 102
contributes to the moment M.sub.F. As the ramp portion 60 moves
toward the stowed position or a deployed position, the lower spring
assembly is engaged, and the moment M.sub.F increases more rapidly,
as shown by the increased slope of the line in the areas where both
the upper and lower spring assemblies 102 and 122 are engaged.
Further, the vertical discontinuities in the graph are achieved by
preloading the springs 104 with adjustment nuts 112A-B.
[0097] As demonstrated in the exemplary embodiment of FIGS. 13-16,
the moment M.sub.F supplied by the counterbalance assembly 100 can
be controlled to more closely approximate the moment M.sub.W
imparted by the weight W of the ramp portion 60. It should be
appreciated that each spring assembly 102, 122 may include a dead
space 126 at one end, both ends, or neither end. Further, preload
in the upper and lower springs 104 may differ as required in order
to provide a moment M.sub.F that more closely approximates the
moment M.sub.W.
[0098] Closeout Assembly
[0099] Referring to FIGS. 17-19, the ramp assembly 20 is provided
with a closeout assembly 140 located at the outboard end of the
frame 30. The closeout assembly 140 limits access to the interior
portion of the frame 30 at the outboard end, thereby reducing the
amount of dirt and debris that can make its way into the interior
portion of the frame 30. This decreases wear of the ramp assembly
20 components. The closeout assembly 140 also provides a step edge
when the ramp portion 60 is in the stowed position, and people
enter and exit the vehicle on foot.
[0100] The closeout assembly 140 includes an end cap 142 that
extends in a forward and rear direction to cover at least partially
the outboard end of the frame 30 when the ramp portion 60 is in the
stowed position. The end cap 142 includes a horizontal, upward
facing surface, which acts as a step edge, and a vertical, outboard
facing surface. An upper end of the end cap 142 is hingedly
connected to the first end 61 of the ramp portion 60 along a hinge
axis 154 that is approximately parallel to the axis of rotation of
the outboard sprocket 88 when the ramp portion 60 is in the stowed
position. The closeout assembly 140 further includes a link 144
that is pivotally coupled at one end to a lower end of the end cap
142 along a hinge axis 155. The other end of the link 144 is
pivotally coupled to the side support 76 of the intermediate panel
assembly 70 along a hinge axis 156.
[0101] Referring to FIG. 17, a hinged panel assembly 146 spans a
space between the end cap 142 and the lower portion of the outboard
end of the frame 30. The hinged panel assembly 146 includes a first
panel 148 hingedly coupled at a first end to a bottom portion of
the end cap 142 along hinge axis 155. A second panel 150 is
hingedly coupled at a first end to a second end of the first panel
148 along hinge axis 157. A second end of the second panel 150 is
hingedly coupled to a lower portion of the outboard end of the
frame along hinge axis 158. The hinge axes 154, 155, 156, 157, and
158 are approximately parallel to the axis of rotation of the
outboard sprocket 88. Further, although the illustrated embodiment
shows the link 144 connected to the end cap fitting 142 along hinge
axis 155, it should be appreciated that the hinged connection
between the link 144 and the end cap fitting 142 need not have a
hinge axis coincident to hinge axis 155, but can instead have a
hinge axis that is offset from hinge axis 155.
[0102] As the ramp portion 60 moves from the stowed position (FIG.
17), in which the closeout assembly 140 is in a closed position,
through the neutral position (FIG. 18) to a deployed position (FIG.
19), in which the closeout assembly 140 is in an open position, the
upper end of the end cap 142 moves in an arcuate path around the
centerline of the outboard sprocket 88. The motion of the ramp
portion 60 also drives the lower end of the end cap 142 via the
link 144 so that the end cap 144 moves around the axis of the
outboard sprocket 88 and out of the path of the ramp portion 60 to
a position generally below the intermediate panel assembly 70. At
the same time, the hinge axis 157 between the first panel 148 and
the second panel 150 travels along an arcuate path to a position
under the frame 30. As a result, as shown in FIGS. 17-19, the
hinged panel assembly 146 folds about the hinge axis 157 between
the first panel 148 and second panel 150, while moving out of the
path of the end cap 142 to a position below the frame 30.
[0103] Latch Assembly
[0104] Referring to FIGS. 20-24, a latch assembly 160 is located at
the inboard end of the ramp assembly 20. The latch assembly 160
engages the ramp portion 60 when the ramp assembly 20 is in the
stowed position to secure the ramp relative to the frame 30. In the
described embodiment, the latch assembly 160 also includes features
to assist an operator with manual deployment of the ramp assembly
20.
[0105] As shown in FIG. 21, the latch assembly 160 includes a latch
fitting 162 pivotally coupled to the frame 30 with a pivot pin 164.
In the illustrated embodiment, the latch fitting 162 and pivot pin
164 are positioned so that the latch fitting 162 is rotatable about
an axis extending in the forward and rear directions, however other
orientations are possible and should be considered within the scope
of the disclosure.
[0106] The latch fitting 162 includes a hook portion 166. When the
ramp portion 60 is in the stowed position, the hook portion 166
engages a latch pin 168, which extends from the ramp portion 60. In
this first position (latched position), engagement of the hook
portion 166 with the latch pin 168 maintains the ramp portion 60 in
the stowed position. A spring 170 is connected at one end to the
latch fitting 162 and at the other end to the frame 30. When the
latch fitting 162 rotates to disengage the hook portion 166 from
the latch pin 168, the spring 170 is extended. As a result, the
spring 170 provides a force that tends to rotate the latch fitting
162 back toward the position in which the hook portion 166 engages
the latch pin 168.
[0107] Referring to FIG. 20, the latch assembly 160 is selectively
operated by an actuator 172. In the illustrated embodiment, the
actuator 172 is a solenoid disposed within the frame 30. The
actuator 172 has an output shaft 174 coupled to a push bar 176 with
an actuation bar fitting 178. The push bar 176 is also coupled to
the latch fitting 162. When the actuator 172 is actuated, the
output shaft 174 of the actuator 172 retracts, moving the push bar
176 in an outboard direction. The motion of the push bar rotates
the latch fitting 162 to a second position (unlatched position),
shown in FIG. 22, wherein the hook portion is disengaged from the
latch pin 168. With the hook portion 166 disengaged from the latch
pin 168, the ramp portion 60 is free to move away from the stowed
position.
[0108] A tang 180 extends from the latch fitting 162 so that the
tang 180 is positioned below a side curb 68 of the ramp portion 60.
When the latch fitting 162 rotates to a third position (lifting
position) shown in FIG. 24, the tang 180 travels upward in an
arcuate path toward the side curb 68. The tang 180 contacts the
side curb 68, and continues to travel along the arcuate path,
thereby imparting a lifting force on the ramp portion 60.
[0109] Referring back to FIG. 21, a latch handle 182 is rotatably
coupled to the latch fitting 162 with a pivot pin 184. Rotation of
the latch handle 182 relative to the latch fitting 162 is limited
by a retainer pin 186 that is attached to the latch fitting 162.
The latch handle 182 is rotatable in a first direction relative to
the latch fitting 162 until the retainer pin 186 engages a first
recess 188 in the latch handle 182, thereby defining a retracted
position. Engagement of the retainer pin 186 with the first recess
188 prevents further rotation of the latch handle 182 in the first
direction relative to the latch fitting 162. Similarly, the latch
handle 182 is rotatable in a second direction relative to the latch
fitting 162 until the retainer pin 186 engages a second recess 190
in the latch handle 182, thereby defining an extended position. A
torsion spring 192 is configured to act as a biasing member,
applying a biasing force that tends to position the latch handle
182 in the retracted position.
[0110] In the illustrated embodiment, the latch handle 182 is
disposed within a slot 194 so that the upper surface of the latch
handle 182 is substantially parallel with the exposed upper surface
of the ramp assembly 20. Sufficient space is provided to enable an
operator to rotate the latch handle 182 by lifting up on the
outboard edge of the latch handle 182.
[0111] The latch assembly 160 further includes a sensor 196 for
sensing the position of the ramp portion 60. In the illustrated
embodiment, the sensor 196 is a limit switch; however, it should be
appreciated that various other sensors, such as proximity sensors,
inclinometers, or any other suitable sensor for detecting ramp
position may be used. When the ramp portion 60 is in the stowed
position, the side curb 68 or some other feature of the ramp
portion 60 engages limit switch 196. As the ramp portion 60 moves
from the stowed position toward a deployed position, the ramp
portion 60 disengages the limit switch 196. Disengagement of the
limit switch 196 interrupts the supply of power to the actuator
172. With power to the actuator 172 interrupted, the spring 170
rotates the latch fitting 162 back to the position that the latch
fitting 162 occupies when the latch fitting 162 engages the latch
pin 168. Disengagement of the limit switch 196 also activates the
vehicle interlock system. As a result, the vehicle is prevented
from moving unless the ramp portion 60 is in the stowed
position.
[0112] FIG. 22 shows the latch assembly 160 in the unlatched
position during a powered unlatch operation. During the powered
unlatch operation, the actuator 172 actuates the push bar 176,
which rotates the latch fitting 162 in a clockwise direction as
viewed in FIG. 22. Rotation of the latch fitting 162 disengages the
hook portion 166 from the latch pin 168. At the same time, the tang
180 contacts the side curb 68 of the ramp portion 60 to provide a
lifting force that assists the drive assembly 80 in moving the ramp
portion 60 from the stowed position. As the ramp portion moves away
from the stowed position, the ramp portion 60 disengages the limit
switch 196, thereby interrupting power to the actuator 172 and
engaging the vehicle interlock system. With power to the actuator
172 interrupted, the latch fitting 162 returns to its original
position due to the force provided by the spring 170.
[0113] When the ramp portion 60 returns to the stowed position, the
latch pin 168 engages an upper surface of the hook portion 166 to
rotate the latch fitting 162 out of the way of the latch pin 168.
When the ramp portion 60 reaches the stowed position, the latch
fitting 162 rotates back due to the force applied by the spring 170
so that the hook portion 166 engages the latch pin 168, thereby
securing the ramp portion 60 in the stowed position.
[0114] FIGS. 23 and 24 show the latch assembly 160 during a manual
unlatch/lifting operation. An operator first pulls upwardly on an
outboard end of the latch handle 182 to rotate the latch fitting
162 into the unlatched position shown in FIG. 23. Pulling on the
latch handle 182 rotates the latch handle 182 until the retainer
pin 186 engages the second recess 190 in the latch handle 182. With
the retainer pin 186 engaging the second recess 190, continuing to
pull on the latch handle 182 rotates the latch fitting 162 until
the latch fitting is in the unlatched position.
[0115] The operator continues to pull on the latch handle 182,
thereby rotating the latch fitting 162 to the lifting position
shown in FIG. 24. In the lifting position, the tang 180 has rotated
in an upward direction to contact the ramp portion 60. As the latch
fitting 162 moves to the lifting position, the tang 180 applies a
lifting force to raise the ramp portion 60. When the latch fitting
162 reaches the lifting position, the ramp portion 60 is raised a
sufficient distance to provide access for the operator to grasp the
ramp portion 60 and manually rotate the ramp portion 60 to a
deployed position.
[0116] In the illustrated embodiment, a latch fitting 162 is
positioned at both the forward and rear sides of the frame 30. Both
latch fittings 162 are actuated by a single actuator 172. It should
be appreciated that alternate embodiments are possible wherein a
single latch fitting 162 is located at a forward, rear, or
intermediate portion of the frame 30. Alternately, multiple
actuators 172 may be included so that each actuator 172 actuates a
different latch fitting 162. Further, in embodiments having
multiple latch fittings 162, one or more of the latch fittings 162
may not have a latch handle 182 coupled thereto. One of skill in
the art will appreciate that other variations in the configuration
and location of the latch assembly 160 components are possible
without departing from the scope of the disclosed subject
matter.
[0117] While illustrative embodiments have been illustrated and
described, it will be appreciated that various changes can be made
therein without departing from the spirit and scope of the
invention.
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