Motor vehicles – Special wheel base
Reexamination Certificate
2001-02-23
2002-11-12
Hurley, Kevin (Department: 3611)
Motor vehicles
Special wheel base
C180S065510, C180S253000
Reexamination Certificate
active
06478099
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a motorized wheeled chassis having a pair of independently pivotable drivewheels and, in particular, to a motorized wheelchair having independently pivotable offset drivewheels, thus enabling true and efficient multidirectional travel.
2. Description of the Related Art
A conventional motorized wheelchair is typically equipped with a chassis having front wheels that consist of a pair of free-spinning castors and rear wheels that consist of a pair of motor-operated wheels which are fixed to the chassis and are frequently driven independently of one another by reversible, variable-speed DC motors. In such wheelchairs, the rotative direction and speed of each of the right and left motor-operated wheels are varied by reversing the power source connection of the appropriate DC drive motor and by regulating the input voltages to the motor, which actions result respectively in switching the direction of movement of the wheelchair (between forward and backward travel) and changing the speed (RPM) of movement of the wheelchair on or along an underlying ground surface. In this manner, a conventional motorized wheelchair is fairly easily advanced, retreated, turned to the right or to the left, and rotated in a stopped state.
However, such a conventional motorized wheelchair cannot be moved laterally with the rider remaining face forward because the motor-operated wheels cannot be pivoted so that they are directed sideways with respect to the rider. This restriction in movement interferes with the rider's ability to utilize the wheelchair completely, to move with total freedom of motion, and to perform certain functions that would be available only through lateral motion as, for example, painting on a horizontally-elongated surface or writing on a blackboard. Moreover, currently known drive wheel control arrangements further restrict the range of wheelchair movements in additional ways and may thereby limit a user's flexibility of motion along particular paths or directions of travel.
In order to solve the problems related to conventional motorized wheelchairs, the inventor of the invention described in this disclosure invented a “Wheeled Chassis Having Independently Pivotable Drivewheels for Omnidirectional Motion”, described in U.S. Pat. No. 5,547,038 (hereinafter referred to as the '038 wheelchair), the entire disclosure of which is incorporated herein by reference. The '038 wheelchair not only allows the rider to face forward while moving laterally, but also provides a minimal turn radius for rotating while remaining in one location.
As shown in
FIG. 1
, the chassis
1
of the '038 wheelchair has a generally rectangular frame
2
with four wheels, one disposed in each corner. In what shall be referred to as the front of the chassis
1
, two wheels, each labeled
4
, are attached to the frame
2
by a shaft
10
that extends along an axis defined generally normal or perpendicular to the ground surface and each links to a bearing assembly
12
. Assembly
12
, at its lower portion, connects to a hub
14
of wheel
4
. By this construction, two independently pivoting, free-spinning wheels
4
are positioned at the front of chassis
1
.
The two wheels at the rear of chassis
1
are the left drivewheel
6
(
a
) and the right drivewheel
6
(
b
). Each drivewheel
6
is attached by a kingpin
16
to frame
2
. Each kingpin
16
at its upward end passes through a channel
18
in frame
2
containing a bearing assembly to provide freedom of selectively controlled pivotal rotation about an axis defined substantially normal to the supporting ground surface. The top end of each kingpin
16
protrudes beyond the top surface of frame
2
and has rigidly connected thereto a drive gear
22
for engagement with a rotative mechanism (not shown). Thus, drivewheel
6
(
a
) may pivotally rotate around substantially vertical axis
23
and drivewheel
6
(
b
) may pivotally rotate around a substantially vertical axis
24
.
The lower portion of each kingpin
16
is rigidly attached to a drivewheel assembly
20
which comprises a variable speed, bidirectional drive motor
8
that rotatably drives the respective drivewheel
6
in a forward or reverse direction. There is no linkage or attachment of the two separate motor drives
8
, and coordination between the two is implemented by a control system (not shown).
With the construction shown in
FIG. 1
, each drivewheel
6
is capable of being pivotally rotated in a complete 360° circle without interference or impediment. Some of the varieties of motion possible with such a construction are shown in
FIGS. 2A-2C
. In
FIG. 2A
, the two rear drivewheels
6
are shown in two different positions (FIG.
2
A
1
and
2
A
2
). In FIG.
2
A
1
, the drivewheels
6
are in a straight (0°) position allowing the wheelchair to be moved straight forward or straight backward. In FIG.
2
A
2
, the two drivewheels
6
are positioned for a minimum radius turning circle. To get to the minimum circle position from the straight position, the right drivewheel
6
(
b
) rotates 45° clockwise and the left drivewheel
6
(
a
) rotates 45° counter-clockwise. In this rotated position, the wheelchair can turn or rotate in place.
It should be noted that the 45° rotation position only applies to a wheeled chassis with a square frame, i.e. with equal length and width, or in which the wheels are mounted at equal front-to-back and side-to-side distances apart. In general, the wheel position for rotation is perpendicular to the diagonal of the chassis frame. As an example, the angle of the rotation position for a frame whose length is longer than its width would be more than 45°. Hereinbelow, although the specification discusses rotation angles such as 45°, 90°, etc., it should be understood that 45°, 90°, etc. are only exemplary rotation angles that are appropriate for a square frame, and the present invention applies to any roughly rectangular frame where the appropriate rotation angles for the different positions may not be 45°, 90°, etc.
In FIG.
2
B
1
the straight position is shown again, while FIG.
2
B
2
shows the straight lateral position which allows the wheelchair to travel straight sideways to the right or the left while the rider remains facing forward. To get to the straight lateral position from the straight position, the right drivewheel
6
(
a
) rotates 90° clockwise and the left drivewheel
6
(
b
) rotates 90° counterclockwise. FIG.
2
C
1
shows the straight position, while FIG.
2
C
2
shows the steered lateral position which allows the wheelchair to travel sideways to the right or left while being controllably steered to alter its course in that direction. To get to the straight lateral position from the straight position, the right drivewheel
6
(
a
) rotates 90° clockwise and the left drivewheel
6
(
b
) rotates 90° clockwise.
In using the prior art '038 wheelchair, use of the straight lateral position shown at FIG.
2
B
2
can become difficult to control once the wheelchair is in straight horizontal motion. This lack of control necessitates that only the steered lateral position shown at FIG.
2
C
2
is used for both straight and curved horizontal movement.
However, this simplification of using only three essential positions—straight, rotation, and (steered) lateral—makes certain common sequences of wheelchair movements unwieldy and particularly wasteful of limited battery power. For example, as shown in
FIGS. 3A-3C
, a wheelchair may be traveling straight (FIG.
3
A), rotate to face another direction (FIG.
3
B), and then move laterally to the right or left (FIG.
3
C). In this sequence of movements, the right drivewheel
6
(
b
) first rotates 45° clockwise and then rotates an additional 45° clockwise. However, the left drivewheel
6
(
b
) first rotates 45′ counter-clockwise and then rotates a full 135° clockwise to reach the lateral position. This sudden change in rotation direction (from counter-clockwise to clockwise) as well as the large required c
LandOfFree
Wheelchair with offset drive wheels does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Wheelchair with offset drive wheels, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Wheelchair with offset drive wheels will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2973757