Wheel chair abstract
The present wheel chair lift apparatus has a rotatable post at
the front of a doorway in the side of a van. A pivotally mounted
electric motor rotates this post through a pinion and gear drive
at the lower end of the post. A carriage for the wheel chair lift
platform is slidable up and down along this post. A vertical lead
screw is coupled to the carriage through a ball nut and a lost-motion
coupling. The lead screw is driven from an electric motor through
a belt and pulley drive at its upper end. The belt is frictionally
restrained to prevent the lift platform from coasting down when
the lead screw drive motor is stopped. The lift platform has a pivoted
retainer lip at its outer edge which is pulled up before the lift
platform can move up or down. The lift platform has a slidable extension
for enlarging its effective size when a wheel chair comes on.
Wheel chair claims
I claim:
1. In a wheel chair lift apparatus on a vehicle having:
a horizontal lift platform;
a rotatable vertical support post;
a carriage slidable vertically along said support post and operatively
coupled to said support post to turn in unison with it;
and means rigidly coupling said lift platform to said carriage
for movement in unison with it;
the improvement which comprises
a rotatable, vertical, power-driven lead screw for raising and
lowering said carriage along said support post;
retractable retainer means operatively associated with said lift
platform for movement between a retracted position in which it permits
the wheel chair to move on or off the lift platform and a raised
position in which it retains the wheel chair on the lift platform;
and means responsive to the operation of the lead screw for maintaining
said retainer means in its raised position whenever the lead screw
is carrying the weight of the carriage and lift platform.
2. An apparatus according to claim 1, wherein said last-mentioned
means includes:
a ball nut engaging the lead screw to move vertically along the
lead screw in response to lead screw rotation;
means operatively coupling said ball nut to said retainer means
for imparting the ball nut movement to said retainer means substantially
without lost motion;
and a lost-motion coupling acting between said ball nut and said
carriage.
3. An apparatus according to claim 2, wherein said means operatively
coupling said ball nut to said retainer means comprises a flexible
cable having its upper end operatively connected to said ball nut
and its lower end operatively connected to said retainer means.
4. An apparatus according to claim 3, wherein said retainer means
is a horizontally pivoted lip at the outer edge of said lift platform.
5. An apparatus according to claim 2, wherein said lost-motion
coupling comprises:
a vertical sleeve affixed to said carriage;
a vertical guide post extending slidably through said sleeve, said
guide post being longer than said sleeve;
upper and lower horizontal plates respectively engaging the top
and bottom of said guide post and extending laterally therefrom
to said lead screw;
and a carrier for the ball nut attached to said upper and lower
plates and extending vertically between them at the lead screw.
6. An apparatus according to claim 5, wherein:
said retainer means is a horizontally pivoted lip at the outer
edge of said lift platform;
and said means for moving the lip from its retracted position to
its raised position is a flexible cable having its upper end attached
to said lower plate in said lost-motion coupling and its lower end
connected to said lip.
7. An apparatus according to claim 5 and further comprising:
a motor-support plate coupled to said support post at its upper
end to turn therewith and extending horizontally therefrom toward
said lead screw;
a lead screw drive motor attached to the bottom of said motor support
plate;
a drive pulley connected to said motor above said motor-support
plate;
a driven pulley connected to the upper end of said lead screw and
overlying said motor-support plate;
and an endless flexible belt operatively engaging said pulleys
to impart the motor drive from the drive pulley to the driven pulley.
8. An apparatus according to claim 7, and further comprising means
for preventing said lead screw from rotating under the weight on
the lift platform when said lead screw drive motor is stopped.
9. An apparatus according to claim 8, wherein said last-mentioned
means comprises a finger which is spring-biased frictionally against
the outside of said belt.
10. An apparatus according to claim 9, and further comprising:
a gear member attached to said support post near its lower end
and extending horizontally therefrom;
a post drive motor;
and a pinion operatively connected to said last-mentioned motor
and meshing with said gear member to rotate said support post from
said last-mentioned motor.
11. An apparatus according to claim 10, and further comprising
means pivotally supporting said post drive motor near the floor
of the vehicle for adjustment from a normal operative position in
which said pinion meshes with said gear member and a retracted position
disengaging said pinion from said gear member.
12. An apparatus according to claim 1, and further comprising:
an extension slidably mounted on said lift platform between a retracted
position in overlapping relationship therewith and an extended position
for increasing the effective size of the lift platform.
13. An apparatus to claim 12, and further comprising:
spring means biasing said extension to its retracted position;
and wherein:
said extension has an upstanding inner end wall for engagement
by the front of the wheels on the wheel chair as the latter rolls
onto the lift platform to push the extension to its extended position
against the bias exerted by said spring means.
14. An apparatus according to claim 2, and further comprising:
a drive motor operatively coupled to said lead screw for rotating
the latter;
and means for preventing rotation of the lead screw under the weight
on the lift platform when said drive motor is stopped.
15. An apparatus according to claim 14, and further comprising:
a motor-support plate coupled to said support post at its upper
end to turn therewith and extending horizontally therefrom toward
said lead screw;
said drive motor being attached to the bottom of said motor-support
plate;
a drive pulley connected to said motor above said motor-support
plate;
a driven pulley connected to the upper end of said lead screw and
overlying said support plate;
and an endless flexible belt operatively engaging said pulleys
to impart the motor drive from the drive pulley to the driven pulley.
16. An apparatus according to claim 15, wherein said means for
preventing rotation of the lead screw when said drive motor is stopped
comprises a finger which is spring-biased frictionally against the
outside of said belt.
17. In a wheel chair lift apparatus on a vehicle having:
a horizontal lift platform;
a rotatable vertical support post;
a carriage slidable vertically along said support post and operatively
coupled to said support post to turn in unison with it;
means rigidly coupling said lift platform to said carriage for
movement in unison with it vertically between a lowered position
outside the vehicle and a raised position outside the vehicle and
horizontally between said raised position outside the vehicle and
a position inside the vehicle;
a rotatable, vertically disposed lead screw;
a follower nut engaging said lead screw for vertical movement therealong;
means coupling said nut to said carriage to move the latter vertically
in response to vertical movement of the nut;
a lead screw drive motor operatively coupled to said lead screw
for driving the latter;
and means for preventing the lead screw from rotating under the
weight on the lift platform when said motor is stopped;
the improvement wherein said motor is operatively coupled to said
lead screw through a drive pulley connected to the motor, a driven
pulley connected to the lead screw, and an endless flexible belt
operatively engaging said pulleys to impart the motor drive from
the drive pulley to the driven pulley, and said last-mentioned means
comprises a finger which is spring-biased frictionally against said
belt.
18. An apparatus according to claim 17, and further comprising:
a motor-support plate coupled to said support post at its upper
end to turn therewith and extending horizontally therefrom toward
said lead screw;
said lead screw drive motor being mounted on the bottom of said
plate;
said drive pulley being connected to said motor above said plate;
and said driven pulley being connected to the upper end of the
lead screw above said plate.
19. An apparatus according to claim 17, wherein:
said driven pulley has a plurality of circumferentially spaced
notches in its periphery;
and said locking finger is spring-biased toward the periphery of
the driven pulley for locking engagement in one of said notches
if the belt breaks.
20. In a wheel chair lift apparatus on a vehicle having:
a horizontal lift platform;
a rotatable vertical support post;
a carriage slidably vertically along said support post and operatively
coupled to said support post to turn in unison with it;
and means rigidly coupling said lift platform to said carriage
for movement in unison with it vertically between a lowered position
outside the vehicle and a raised position outside the vehicle and
horizontally between said raised position outside the vehicle and
a position inside the vehicle;
the improvement which comprises;
a gear member attached to said support post near its lower end
and extending horizontally therefrom;
a post drive motor;
a pinion operatively connected to said last-mentioned motor and
meshing with said gear member to rotate said support post from said
last-mentioned motor;
and means pivotally supporting said post drive motor near the floor
of the vehicle for adjustment from a normal operative position in
which said pinion meshes with said gear member and a retracted position
disengaging said pinion from said gear member.
21. In a wheel chair lift apparatus on a vehicle having:
a horizontal lift platform;
means for lowering said lift platform to a position outside the
vehicle and for raising said lift platform from said lowered position
outside the vehicle;
and means for swinging the raised lift platform horizontally into
or out of the vehicle;
the improvement which comprises:
an extension slidably mounted on said lift platform between a retracted
position in overlapping relationship therewith and an extended position
for increasing the effective size of the lift platform;
and spring means biasing said extension to its retracted position.
22. A lift apparatus according to claim 21, wherein said extension
has an upstanding inner end wall for engagement by the front of
the wheels on the wheel chair as the latter rolls onto the lift
platform to push the extension to its extended position against
the bias exerted by said spring means.
23. A lift apparatus according to claim 22, and further comprising:
a retainer lip pivoted to the outer end of said lift platform;
and means for raising said lip to extend up from the lift platform
when the lift platform is to be raised.
Wheel chair description
BACKGROUND OF THE INVENTION
This invention relates to a vehicle-mounted wheel chair lift apparatus
of the general type disclosed in our U.S. Pat. No. 3,847,292. The
lift apparatus of that patent includes a horizontal lift platform
which is normally stored in the van. When the occupant of a wheel
chair wants to enter the van, the lift platform is raised slightly
and then is pivoted horizontally out of the van and lowered vertically.
After the wheel chair is on this platform it is elevated to a raised
position outside the van and then is pivoted horizontally into the
van slightly above floor level and then lowered to floor level.
The reverse sequence of operations is carried out when the wheel
chair occupant wants to leave the van. Various power-operated devices
and controls are provided for effecting these operations with a
minimum of effort required of the wheel chair occupant.
SUMMARY OF THE INVENTION
The present invention is directed to a wheel chair lift apparatus
of the same general type but with several modifications to simplify
and improve the reliability and safety of its operation.
In the presently preferred embodiment of this invention the raising
and lowering of the lift platform is effected through a vertical
lead screw which drives a ball nut. Preferably, a lostmotion coupling
is provided between the ball nut and a carriage which is slidable
vertically along a rotatably supported post. The carriage is coupled
rigidly to the lift platform. The lostmotion coupling delays briefly
the up or down movement of the carriage and the lift platform when
the lead screw first begins to turn in either direction.
In this embodiment the lead screw is driven through a belt and
pulley drive at its upper end from an adjacent electric motor. A
brake applies friction to the belt to prevent the lift platform
from coasting down when this motor is stopped. This brake automatically
locks the lead screw in case the belt breaks.
The vertical post is rotated by a second electric motor through
a gear drive. This motor is pivotally mounted at the floor of the
vehicle for selectively disconnecting this gear drive.
The lift platform has a pivoted retainer lip at its outer edge
for preventing the wheel chair from rolling off. This lip is raised
by the ball nut whenever the lead screw is supporting the weight
of the lift platform.
The lift platform also has a slidable extension which is engageable
by the wheels of the wheel chair to enlarge the effective size of
the lift platform when the wheel chair rolls onto it.
A principal object of this invention is to provide a novel and
improved wheel chair lift apparatus on a motor vehicle, particularly
a van.
Another object of this invention is to provide such an apparatus
which is relatively simple mechanically while at the same time being
reliable and safe in operation.
Another object of this invention is to provide a novel wheel chair
lift apparatus on a vehicle which uses a motor-driven vertical lead
screw for raising and lowering a horizontal lift platform.
Another object of this invention is to provide a lift apparatus
as just mentioned in which the lead screw is driven through a belt
and pulley drive provided with a frictional restraint for preventing
the lift platform from coasting down when the lead screw drive motor
is stopped.
Another object of this invention is to provide a novel wheel chair
lift apparatus having a vertical lead screw for raising and lowering
the lift platform, a vertically reciprocable carriage rigidly connected
to the lift platform, and a novel lost-motion coupling acting between
the lead screw and the carriage.
Another object of this invention is to provide a novel wheel chair
lift apparatus as just described which has a retractable wheel chair
retainer on the lift platform which is coupled to the lead screw
substantially without lost motion so as to be raised to its wheel
chair retaining position substantially as soon as the lead screw
is turned in either direction for raising or lowering the lift platform
through the lost-motion coupling and carriage.
Another object of this invention is to provide in a wheel chair
lift apparatus a novel extension on the lift platform for automatically
enlarging its effective size when a wheel chair is on the platform.
Further objects and advantages of this invention will be apparent
from the following detailed description of a presently-preferred
embodiment thereof, which is shown in the accompanying drawings
in which:
FIG. 1 is an elevational view of a van with its sliding side door
open and with the present wheel chair lift lowered outside the van;
FIG. 2 is a perspective view of the present lift apparatus in its
lowered position outside the van.
FIG. 3 is a horizontal cross-section taken along the line 3--3
in FIG. 2;
FIG. 4 is a fragmentary vertical end view showing part of the lead
screw and ball nut assembly in this lift apparatus;
FIG. 5 is an elevational view of the lift apparatus taken from
the left side in FIG. 2 and broken away for clarity;
FIG. 6 is a fragmentary top plan view of the belt and pulley drive
for the lead screw at the top of the apparatus;
FIG. 7 is a view similar to FIG. 6 but showing the pulley belt
broken and the lead screw pulley braked;
FIG. 8 is an enlarged fragmentary cross-section taken along the
line 8--8 in FIG. 7 and showing the pulley brake engaged;
FIG. 9 is a view similar to FIG. 1 but with the wheel chair lift
inside the van;
FIG. 10 is an elevation similar to FIG. 5 but with parts shown
in their position after the lift platform has been raised to slightly
above the van floor level;
FIG. 11 is a schematic top plan view showing the raised lift platform
swung from the phantom-line position outside the van to the full-line
position inside the van;
FIG. 12 is a fragmentary top plan view of the middle of the lift
platform, with parts removed for clarity;
FIG. 13 is a longitudinal vertical section taken along the centerline
of the lift platform, as shown at 13--13 in FIG. 2; and
FIG. 14 is a vertical section taken along the line 14--14 in FIG.
2 at one side edge of the lift platform.
Before explaining the present invention in detail, it is to be
understood that the invention is not limited in its application
to the details of construction and arrangement of parts illustrated
in the accompanying drawings, since the invention is capable of
other embodiments and of being practiced or carried out in various
ways. Also, it is to be understood that the phraseology or terminology
employed herein is for the purpose of description and not of limitation.
The invention is illustrated herein as applied to an automotive
van 20 having a sliding door 22. A particular embodiment of the
invention has been installed on a Chevrolet sliding door van, 10
Series. However, it will be understood that the invention may be
applied to other vehicles.
In the van 20 the driver's seat is removed so that a wheel chair
24 can be positioned under the steering wheel. The van is especially
equipped to enable the occupant of the wheel chair to drive the
vehicle seated in the wheel chair 24 even though the driver may
be partially disabled. Preferably, the van 20 has power brakes,
power steering, and automatic transmission, and suitable controls
are provided in known manner (not shown) to enable the occupant
of the wheel chair to drive the van. The invention is not specifically
directed to these driving controls, so they are not illustrated
herein.
A support 26 in the form of a squared tubular post is mounted inside
the vehicle at the front edge of a door opening 52 in its right
side. The door opening is normally closed by a sliding door 22.
Support post 26 is rotatably mounted on a base 28, as best seen
in FIG. 5. A reduced cylindrical pivot pin 30 on the lower end of
post 26 is rotatably received in the base 28. At the upper end of
post 26 a similar pivot pin 34 is rotatably received in a flanged
bushing 33 carried by an upper bracket 32 near the top of the door
opening 52. As shown in FIG. 2, the base 28 is mounted on the door
step 36 of the van, and the bracket 32 is attached to a door post
38 so that the post 26 is located inside the vehicle.
A carriage 40 of square cross-section is slidably mounted on the
outside of the post 26 for up and down movement. A lift platform
44 is rigidly attached to the vertically slidable carriage 40 by
means of rigid, interconnected brace members 41, 42, 43, 45, 46
and 47, as best seen in FIG. 2. These brace members form a rigid
frame suspending the lift platform 44 from the carriage 40 such
that the carriage, frame and platform can move together up and down
along the support post 26. The frame and platform are also movable
horizontally in and out of the doorway 52 when the door 22 is open
since the support post 26 is rotatable relative to the base 28 and
the bracket 32.
A ball nut 48 (FIGS. 3 and 5) is carried by a three-sided rectangular
bracket or housing 48a which, as shown in FIG. 5, extends vertically
between upper and lower horizontal plates 49 and 50 and is welded
to both of them. A vertical guide post 51 extends between the upper
and lower plates 49 and 50 near the vertically slidable carriage
40. A vertical sleeve 52 is welded at 53 to the carriage 40 and
slidably receives the guide post 51. The sleeve 52 is shorter than
the guide post 51 and therefore the unitary assembly of the ball
nut carrier 48a, upper and lower plates 49 and 50, and guide post
51 can move up and down a limited amount with respect to the sleeve
52 and the carriage 40 which supports the sleeve.
The ball nut 48 engages a vertically elongated lead screw 54. The
lower end of this lead screw carries an elongated pivot pin 55 (FIG.
5) which is rotatably received in an antifriction bushing 56. This
bushing is carried by an upstanding hollow collar 57 on the outer
end of a rigid horizontal arm 58, whose opposite end is rigidly
joined to the post 26 a short distance above the latter's lower
end.
A horizontally disposed gear sector 59 is welded to the post 26
and the underside of the connecting arm 58. This gear sector is
engaged by a pinion 60 (FIG. 5) driven through a gear reduction
61 from an electric motor 62 above. This post driven motor and gear
reduction unit is mounted on a normally horizontal panel 63, which
is pivotally connectd at 64 to the lower end of a vertical wall
segment 65 of the van body at its doorway 52. Normally, the pivoted
motor-support panel 65 is rigidly attached by bolts 66 to a rigid
spacer 67 which extends up from the floor 68 of the van, as shown
in full lines FIG. 5. However, after removing the bolts, the motor-support
panel 63 may be pivoted up to the phantom-line position in FIG.
5 so as to disengage the motor-driven pinion 60 from the gear sector
59. This facilitates servicing of this pinion-and-gear drive.
The upper end of the lead screw 54 carries a pulley 70 which is
driven through a flexible endless belt 71 from a smaller pulley
72 (FIG. 2) which is driven by an electric motor 73. This lead screw
drive motor is mounted on the bottom of a horizontal support plate
74 which, as shown in FIG. 5, has a circular opening 75 through
which the upper pivot pin 34 on the post 26 extends. Adjacent this
opening 75 the plate 74 is clamped between a transverse, upwardly-facing
shoulder 26a on the post 26 at the lower end of its upper pivot
pin 34 and the transverse flange on the bottom of the bushing 33,
so that the plate 74 will turn in unison with the post 26 when the
latter is rotated.
As shown in FIG. 5, the motor-support plate 74 has another vertical
opening 76 in which is located a flanged anti-friction bushing 77
which receives a pivot pin on the upper end of the lead screw 54.
The pulley 70 is fastened to this upper pivot pin and it rests on
the flange of bushing 77 which overlies the motor-support plate
74 at the opening 76 in the latter.
In accordance with an important aspect of this invention the lead
screw 54 is frictionally restrained against rotating when its drive
motor 73 is stopped. The weight on the lift platform and the very
low friction between the ball nut 48 and the lead screw would tend
to produce slow rotation of the lead screw that would cause the
lift platform to coast down when motor 73 is not raising it. A flexible
and resilient finger 79 of spring steel or other suitable material
is fastened at one end to a boss or post 80 which extends up from
the motor-support plate 74, as best seen in FIG. 2. A coil spring
81 urges the hooked opposite, free end 82 of the spring finger 79
clockwise in FIG. 6. Normally a curved portion 83 of the finger
between its hooked, free end 82 and the coil spring 81 bears frictionally
against the outside of the belt 71, exerting enough restraint to
prevent the lead screw from being turned by the weight on the lift
platform in a direction for lowering the lift platform when motor
73 is off. Also, if the belt 71 breaks (FIG. 7), the hooked end
of finger 79 will move into engagement with the periphery of the
pulley 70 and will snap into the first notch 78 in the latter's
periphery to reach it, so as to lock the pulley 70 and the lead
screw 54 against rotation.
In accordance with another important aspect of this invention the
horizontal lift platform 44 is provided with a pivoted retaining
lip 85 at its outer edge. Normally, as shown in FIG. 2, this lip
extends horizontal, substantially co-planar with the floor of the
lift platform 44. After the wheel chair is on the lift platform,
the lip 85 may be pivoted up (counter-clockwise in FIG. 2) to the
upwardly projecting position (shown in FIG. 1) behind the adjacent
wheel 24 of the wheel chair, so that the wheel chair cannot accidentally
roll off the lift platform.
The lip 85 is pivotally actuated through a Bowden wire 86 which
has its upper end hooked to an eye 87 (FIGS. 4 and 5) integral with
the aforementioned lower plate 50 associated with the ball nut 48.
The Bowden wire extends slidably through a curved guide sleeve 88
which has its upper end welded or otherwise attached at 89 (FIG.
2) to the upstanding brace member 41 and its lower end similarly
attached at 90 to the lift platform 44.
Normally, the parts are positioned as shown in full lines in FIG.
5, with the Bowden wire 86 slack, the retainer lip 85 extending
horizontally out from the lift platform 44, the upper plate 49 resting
on top of the carriage-attached sleeve 52, and the lower plate 50
spaced below the bottom of sleeve 52. When the unitary assembly
of the ball nut housing 48a, upper and lower plates 49 and 50, and
guide post 51 moves up with respect to the carriage-attached sleeve
52, to the phantom-line position in FIG. 5, the Bowden wire 86 is
pulled up with it and it pulls the retainer lip 85 up to the phantom-line
position shown, in which it projects up from the outer edge of the
lift platform.
A limit switch 92 is carried by a bracket 93 welded to the vertically
slidable carriage 40. The movable actuator 94 for this switch is
positioned to be engaged by the lower plate 50 which is part of
the lost-motion coupling between the ball nut 48 and the carriage
40. When the weight of this carriage, the rigid framework 41-47
and the lift platform 44 is not being carried by the lead screw
54, such as when the lift platform is resting on a sidewalk or on
the van floor, the switch actuator 94 will be engaged by plate 50
(for example, as shown in full lines in FIG. 5). When the lead screw
54 is supporting the weight of the lift platform, carriage and framework,
the lower plate 50 will be displaced up away from engagement with
the switch actuator 94. Thus, the switch 92 senses whether or not
the lead screw is carrying this weight.
Limit switch 92 is normally closed and is operatively connected
electrically to the motor 73 for stopping the latter when the lift
platform can be lowered no farther. A manual switch is provided
for raising and lowering the lift platform. With the manual switch
held in its "lower" position the platform will come down
until limit switch 92 is operated (opened) and this shuts off the
motor 73.
A normally closed upper limit switch 95 with a pivoted actuator
96 is mounted on the bottom of the support plate 74 for the lead
screw motor 73. The switch actuator 96 is positioned in the path
of upward movement of a bolt 97 whose lower end is threaded into
a fitting 98 on top of the inclined brace member 47. A lock nut
99 threadedly engages the bolt 97 above this fitting to lock the
bolt in any vertical position to which it has been threadedly adjusted.
Switch 95 is connected to the lead screw drive motor 73 to turn
it off when its actuator 96 is engaged by the bolt 97 after the
carriage 40 and lift platform have moved up. The manual switch is
held in its "raise" position to energize motor 73 for
raising the lift platform until the upper limit switch 95 is operated
(opened) and shuts off motor 73.
In accordance with another aspect of the present invention, the
lift platform has a slidable extension 100 overlying the main section
44 of the lift platform at its inner edge. This extension has a
flat bottom wall 101, upstanding opposite sides 102 and 103 with
outwardly projecting horizontal flanges 102a and 103a at their upper
ends, and an upwardly inclined end wall 104 at the end away from
the pivoted retainer lip 85 on the outer edge of the lift platform.
When the wheels of the wheel chair roll onto the lift platform
(from right to left in FIG. 2) they engage the end wall 104 of the
extension 100 and move the latter from the normal full-line position
to the inwardly extended phantom-line position in FIG. 2.
The main section 44 of the lift platform has a centrally located,
upwardly projecting ear 105 (FIGS. 12 and 13) inside a tunnel 106
(FIG. 2) on top. A tension coil spring 107 is connected at one end
to this ear and at its opposite end to a centrally located, longitudinally
extending, inverted T-shaped rib 108 attached to the top of the
slidable extension 100 and extending horizontally outward from it
across the top of the main section 44 of the lift platform. Spring
107 biases the extension 100 to the retracted, full-line position
in FIG. 13 but permits the extension to be displaced to inwardly
extended, phantom-line position.
The aforementioned ear 105 rotatably supports a roller 109 which
overlies one horizontal bottom leg of the inverted T-shaped rib
108 on the lift platform extension 100. A similar ear 110 extends
up from the main section 44 of the lift platform on the opposite
side of the ear 108 and it carries a roller 111 which overlies the
bottom leg of the ear on this side. These two sets of ears and roller
105, 109, 110 and 111 guide the longitudinal rib 108 on the lift
platform extension 100 as it slides in either direction over the
main section 44 of the lift platform.
As shown in FIG. 14, at the right side of the lift platform in
FIG. 2 a pair of upper and lower cylindrical guides 112 and 113
extend above and below the side flange 102a on the lift platform
extension 110. These guides are carried by a U-shaped support member
114 which is welded to the vertical frame piece 42 at this side
of the lift platform.
A similar guide arrangement is mounted on the vertical frame piece
41 on the left side of the lift platform in FIG. 2, presenting upper
and lower guides above and below the corresponding side flange 103a
on the slidable extension 100 of the lift platform.
The tunnel 106 on top of the main section 44 of the lift platform
is longitudinally slotted at 115 on each side at its inner end to
slidably receive the bottom wall 101 of the slidable extension 100,
as shown in FIG. 2.
OPERATION
In the operation of this apparatus, with the van door 22 open (FIG.
1), the lift platform is lowered onto the sidewalk or street surface
on which the wheel chair rests. With the retainer lip 85 on the
lift platform in its lowered, horizontally extended position, the
wheel chair is rolled onto the lift platform. The wheels of the
wheel chair engage the inclined inner end wall 104 of the lift platform's
slidable extension 100 and push the latter from the retracted, normal,
full-line position in FIG. 2 to the inwardly extended, phantom-line
position, thereby effectively enlarging the size of the lift platform.
When the user operates the manual switch for raising the lift platform,
the first thing that happens is that the retainer lip 85 on the
outer edge of the lift platform is pivoted up to the raised position
shown in FIG. 1, so as to engage the back of one of the wheels and
prevent the wheel chair from accidentally rolling off the lift platform.
This initial action takes place as follows:
The manual "raise" switch turns on the motor 73 which
drives the lead screw 54 in a direction for raising the ball nut
48. The upward movement of the ball nut is imparted first to the
unitary assembly of the three-sided ball nut carrier 48a, the upper
and lower plates 49 and 50, and the guide post 51, so that this
unitary assembly first moves up about an inch from the full line
position in FIG. 5 (FIG. 2 also) to the phantom-line position in
FIG. 5 (which is the full-line position in FIG. 10). The carriage
40 remains stationary during this initial movement and the unitary
ball nut assembly moves up with respect to the guide sleeve 52 fixed
to the carriage. This initial upward movement of the ball nut is
imparted through the Bowden wire 86 to the retainer lip 85 to pivot
the latter up to its wheel-retaining position, shown in phantom
FIG. 5.
Continued rotation of the lead screw 54, after the bottom plate
50 in the lost-motion coupling engages the lower end of the guide
sleeve 52, now causes the carriage 40 to move up in unison with
the ball nut assembly. The carriage 40 slides up along the vertical
post 26, carrying the lift platform with it. This lost-motion upward
movement of the bottom plate 50 also releases the actuator 94 for
the lower limit switch 92, so that the release of this switch occurs
when the lead screw 54 begins to carry the weight of the carriage,
framework and lift platform.
When the upper limit switch actuator 96 is operated, the lead screw
motor 73 is turned off. This happens when the bottom of the lift
platform has reached a vertical position slightly higher than the
floor of the vehicle.
The next step is to rotate the post 26 to bring the lift platform
from its raised position outside the vehicle to a raised position
inside the vehicle. This may happen automatically following the
actuation of the upper limit switch 95 or it may be effected through
a manual switch operated by the occupant of the wheel chair. In
either case the motor 62 now is turned on and through the pinion
60 and gear sector 59 it rotates the post 26 in a direction to swing
the lift platform inside the van slightly above the floor of the
van.
At the completion of this operation, the post drive motor 62 is
turned off, either automatically or manually, and motor 73 is energized,
either automatically or through a manual switch, to drive the lead
screw 54 in the reverse direction for lowering the ball nut assembly.
The lift platform is lowered onto the floor of the van and then
as the lead screw 54 continues to run in reverse it causes the ball
nut assembly to move down with respect to the now-stationary guide
sleeve 52 and the carriage 40. This causes the Bowden cable 86 to
lower the retaining lip 85 on the lift platform, so that the wheel
chair can be rolled off the lift platform onto the floor of the
van.
When the wheel chair is to be moved out of the van onto the sidewalk,
for example, the foregoing operating sequence is reversed.
It will be evident from the foregoing that the lost-motion coupling
which acts between the ball nut 48 and the carriage insures that
the retaining lip 85 on the lift platform will be in its raised
position whenever the lead screw 54 is carrying the weight of the
lift platform. The retaining lip 85 will be down only when the lift
platform has its weight resting on some support surface, such as
the van floor or the sidewalk outside.
With the lead screw drive motor 73 stopped, the weight of the wheel
chair and its occupant on the lift platform, acting through the
low friction coupling between the ball nut 48 and the lead screw
54, is prevented from slowly rotating the lead screw in a direction
for lowering the lift platform because of the frictional restraint
which the finger 79 exerts on the pulley belt 71. Accordingly, under
these circumstances the lift platform cannot coast down along the
lead screw. Also, if the pulley belt 71 breaks this finger 79 will
automatically engage a notch in the pulley 70 on the upper end of
the lead screw 54 to prevent lead screw rotation. |