Tie down loop for motorized wheelchair

Information

  • Patent Grant
  • 6234732
  • Patent Number
    6,234,732
  • Date Filed
    Friday, November 13, 1998
    26 years ago
  • Date Issued
    Tuesday, May 22, 2001
    23 years ago
Abstract
A wheelchair includes a base frame having a longitudinal axis, and a forward end and a rearward end joined by a first side frame and a second side frame, each side frame being generally parallel to the longitudinal axis. The wheelchair also includes a first motor and a second motor. A first mounting bracket is affixed on the first side frame and a second mounting bracket affixed on the second side frame. The first and second mounting brackets have a main body including a motor gear bore for securing the first motor or the second motor, a front tie down point directed toward the forward end of the frame, and a rear tie down point directed toward the rearward end of the frame.
Description




BACKGROUND OF THE INVENTION




This invention relates in general to wheelchairs and more particularly, to tie down points for wheelchairs. Most particularly, the invention relates to a tie down bracket for wheelchairs to create tie down points for securing a wheel chair in a vehicle.




Wheelchairs generally include a frame that supports a pair of drive wheels and a pair of front casters. The drive wheels and casters are typically rigidly supported by the wheelchair frame. The drive wheels make contact with the ground and are driven to propel the wheelchair. The drive wheels may be driven manually or powered by an electrical motor. The wheelchair supports a seat assembly comprising a seat and a backrest. The seat assembly is oriented above and between the drive wheels and the front casters to provide stability.




Wheel chairs are frequently transported in vehicles with the user in them. Typically, the user drives the wheelchair onto a lift attached to the vehicle. The lift is operated to raise the wheelchair into the vehicle. The user stays in the wheelchair while the vehicle is being driven. Often, the wheelchair is secured simply by setting the brakes. Perhaps some minimum kind of tie down is provided. At worst this tie down might consist of nothing more than opposing shock cords that do little more than prevent rocking of the wheelchair as the vehicle turns. At best, high-test nylon webbing is looped through any convenient location in the frame or wheels.




Tremendous forces are generated inside a vehicle every time an accident occurs. These forces are so great that it is not uncommon for individuals secured to a vehicle seat with a lap and shoulder harness to suffer injuries ranging from deep bruising to cracked ribs. Obviously, someone sitting in an unsecured or barely secured wheelchair will be severely injured. The likelihood of injury decreases if the wheelchair is secured with webbing. However, the combination of a motorized wheelchair and its user can easily weigh 500 lbs. (227 kg). In an accident, the force generated by such mass is focused at the point where the webbing passes through the frame or wheels. Considering that typical casual tie down points are not engineered to withstand such focused forces, its not surprising that wheelchairs fail to stay secured in place during vehicle accidents.




Thus is would be desirable to have tie down points through which a wheelchair could be safely and securely tied down in a vehicle.




SUMMARY OF THE INVENTION




The above objects as well as other objects not specifically enumerated are achieved by a wheelchair comprising a base frame having a longitudinal axis, and a forward end and a rearward end joined by a first side frame and a second side frame, each side frame being generally parallel to the longitudinal axis. The wheelchair also includes a first motor and a second motor. A first mounting bracket is affixed on the first side frame and a second mounting bracket affixed on the second side frame. The first and second mounting brackets have a main body including a motor gear bore for securing the first motor or the second motor, a front tie down point directed toward the forward end of the frame, and a rear tie down point directed toward the rearward end of the frame.




According to this invention there is also provided a mounting bracket for supporting a motor for a wheelchair, the mounting bracket providing front and rear tie down points. The mounting bracket comprises a main body configured, such as with a series of bores, to be attached to the wheelchair, and also comprises a bore for securing the motor. A front portion of the main body defines the front tie down point, and a rear portion of the main body defines the rear tie down point.











Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.




BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a perspective view of a base frame assembly of a wheelchair showing an embodiment of the invention.





FIG. 2

is a view in elevation of an embodiment of the bracket of the invention illustrating angled front and rear tie down points with the rear tie down point positioned in a different plane from the plane of the bracket.





FIG. 3

is a cross-sectional view of the rear tie down point taken along line


3





3


of

FIG. 2

, illustrating the offset between the plane defined by the rear tie down point and the plane defined by the main body of the bracket.





FIG. 4

is a view of an embodiment of the bracket of the invention illustrating angled front and rear tie down points, with the front tie down point, rear tie down point, and main body all positioned in the same plane.





FIG. 5

illustrates a variation on the shaping of the bracket shown in FIG.


2


.





FIG. 6

illustrates a variation on the shaping of the bracket shown in FIG.


4


.





FIG. 7

is a cross-sectional view in elevation of a mounting bracket tie down point illustrating minimum shaping requirements for the tie down opening to be engaged by end fittings of strap-type tie down assemblies that are in compliance with ISO 10542.





FIG. 8

is a cross-sectional view along line


8





8


of

FIG. 7

illustrating minimum shaping requirements for the portion of the mounting bracket immediately adjacent the tie down opening.





FIG. 9

is a view similar to that of

FIG. 9

, but having a rectangular wall construction.





FIG. 10

shows a wheelchair that includes the bracket of the invention, with the wheelchair being tied down to a vehicle floor.











DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT




The present invention is directed to a mounting bracket for supporting a motor for a wheelchair and simultaneously providing integrated front and rear tie down points for securing the wheel chair in a vehicle, aircraft, boat, etc.




Referring now to the drawings, there is illustrated in

FIG. 1

, a perspective view of a base frame assembly


10


of a wheelchair showing an embodiment of the invention. The frame


10


has a longitudinal axis, illustrated generally by the line


99


running from left to right in the Figure. The frame also has a forward section


11


(on the left side of the Figure), having a pair of front casters


98


, and a rearward section


12


. The rear wheels are not shown in the drawing so that the invention can be better seen. The forward end


11


and the rearward end


12


are joined by a first side frame


13


and a second side frame


14


. Each side frame


13


,


14


is preferably oriented in a plane, not shown, that is generally parallel to the longitudinal axis


99


approximately parallel to the horizontal axis.




A motor


97


is affixed, either directly or indirectly, to the side frame


13


of the wheelchair frame


10


. A second motor (not shown) is affixed to the side frame


14


of the wheelchair base frame. The described positioning of the motor is illustrative and is in no way intended to limit the invention.




A first mounting bracket


20


is affixed to the first side frame


13


and a second mounting bracket


30


is affixed to the second side frame


14


(only a small portion of the mounting bracket


30


is visible), as shown in FIG.


1


. The first mounting bracket


20


and the second mounting bracket


30


as shown are mirror images of each other. Alternatively, the first mounting bracket and the second mounting bracket may be identical or dissimilar depending on the wheelchair. While the following discussion focuses on the first mounting bracket


20


, the same description also applies to the second mounting bracket


30


. If the first bracket


20


and second bracket


30


were dissimilar, such dissimilarities would not affect this description.




As shown in

FIGS. 1 and 2

, the first mounting bracket


20


has a main body


21


having a motor gear bore


26


for receiving the drive gear


19


for the drive wheel. The drive wheel is indicated at


71


in FIG.


10


. The drive wheel is mounted for rotation on an axle


18


. The motor


97


drives the drive gear


19


which rotates the drive wheel to propel the wheelchair. The axle is mounted through the bore


26


and the drive gear


19


, and hence the drive wheel is indirectly mounted for rotation from the bracket


20


. It is to be understood that any suitable motor and gear combination can be used. As illustrated, the motor is secured to the bracket by the mounting of the drive gear through the bracket bore


26


, although the motor can be secured to the bracket in any other suitable manner.




A front tie down point


23


is positioned in a front portion


22


of the bracket. The front portion


22


is oriented toward or directed toward the front or forward end of the base frame


11


. A rear tie down point


25


, positioned in a rear portion


24


of the bracket


20


, is directed toward the rearward end of the frame. (

FIG. 1

also illustrates the front tie down point


33


of the second mounting bracket


30


.) A variety of bores


88


through the main body


21


provide convenient points for affixing the mounting bracket


20


to the side frames of the wheelchair. It is to be understood that other methods of fixing the mounting bracket to the wheelchair can be used.




The main body


21


and the front portion


22


are positioned in a first plane (indicated by line


28


in FIG.


3


), and the rear tie down point


25


is positioned in a second plane (indicated by line


29


in

FIG. 3

) spaced apart from and generally parallel to the first plane


28


. The tie down point


25


defines a second plane


29


, and is attached to the first plane


28


, defined by the main body


21


, by a curved connector section or offset


27


. This offset


27


permits the rear tie down


25


to be configured to better fit the wheelchair frame


10


and to create contact points that distribute forces from the mounting bracket


20


or


30


to the frame


10


. The amount of distance between the two planes


28


and


29


is preferably within the range of from about 0.5 to about 5 cm, and more preferably within the range of from about 1 to about 3 cm, although other spacings could also be used.




In an alternative embodiment of the invention, as shown in

FIG. 4

the various portions of the bracket can be positioned all in the same plane. As shown, this alternative mounting bracket


40


has a main body


41


, and includes the motor gear bore


46


. The front portion


42


includes the tie down point


43


, and the rear portion


44


includes the tie down point


45


, all of which are positioned in the same plane.





FIGS. 1-4

illustrate embodiments of the invention where the front portions


22


,


42


containing the front tie down points


23


,


43


, and the rear portions


24


,


44


where the rear tie down points


25


,


45


are located, are formed as extensions or tabs projecting longitudinally from the main body


21


,


41


of the mounting bracket


20


,


40


. The extensions or tabs of the front tie down points are preferably oriented at an angle


48


within the range of from about 30 to about 90 degrees to the vertical, and preferably about 50 degrees to the vertical. The extensions or tabs of the rear tie down points are preferably oriented at an angle


49


within the range of from about 20 to about 70 degrees to the vertical, and preferably about 35 degrees to the vertical.





FIGS. 5 and 6

illustrate variations in the shaping of brackets according to another embodiment of the present invention.

FIG. 5

illustrates a bracket


50


formed with the front portion


52


and rear portion


54


being designed without being in the shape of the extensions or tabs that are shown in

FIGS. 1 and 2

. The main body


51


with the motor gear bore


56


and the front portion


52


containing the front tie down point


53


, is formed in one plane. The rear portion


54


containing the rear tie down point


55


is in a second plane that is spaced apart from the main body


51


and the front portion


52


by an offset


57


. Preferably the second plane is generally parallel to the first plane, although this does not necessarily need to be the case. Similarly,

FIG. 6

illustrates a bracket


60


that is formed without the extensions or tabs containing the front tie down point


62


and the rear tie down point


64


as shown in

FIGS. 1

,


2


, and


4


. In

FIG. 6

, the main body


61


with the motor gear bore


66


and the front potion


62


containing the front tie down point


63


are in the same plane as the rear tie down point


65


.




Preferably, the front tie down points


23


,


33


,


43


,


53


, and


63


and the rear tie down points


25


,


45


,


55


, and


65


are positioned on the mounting bracket to accommodate wheelchair tie down approach angles ranging from 20° to 45° as measured from the support surface on which the wheelchair rests. As shown in

FIG. 10

, the tie down approach angle is the angle


67


between the floor


68


of a vehicle and the tie down straps


69


.




Compatibility between a wheelchair and tie down point is essential for maximizing access, safety, and convenience. This is particularly true in public transportation where a variety of wheelchair designs must be accommodated using the same tie down system. Obviously, the time required to tie down a wheelchair is important in the efficient operation of public transportation, and the strength and security of the tie down system during a crash can determine whether the occupant of the wheelchair is protected. Annex D of ISO 10542 establishes geometric design a requirements for wheelchair tie down points intended to be engaged by the end fittings of strap-type tie down assemblies that are in compliance with the ISO 10542 standard. Accordingly, it is preferred that mounting brackets of the present invention have dimensions in accordance with the design specifications of Annex D. Such dimensions are illustrated in

FIGS. 7-9

. The tie down opening


301


of the mounting bracket tie down point


300


, as shown in

FIG. 7

, generally has a minimum height 200 of 60 mm and minimum width 201 of 25 mm. The interior comers


207


of the opening


301


have a minimum radius of 5 mm to avoid sharp corners that could cut the strap.





FIG. 8

illustrates a permissible configuration of the wall portion


302


that defines the opening


301


. If circular or ovoid, the longest dimension


202


of the cross section of this wall portion must be a minimum of 30 mm, with a minimum radius at the corners of 5 mm. As shown in

FIG. 9

, if the cross section


303


is rectangular, the minimum diagonal


203


must be 30 mm with rounded edges having a minimum radius of 5 mm. Overall, the tie down points of the mounting bracket must be positioned to accommodate wheelchair tie down approach angles within the range of from about 20° to about 45° from the support surface on which the wheelchair rests.




As shown in

FIG. 10

, the wheelchair


70


includes drive wheels


71


, seat


72


and seat back


73


. The bracket


20


of the invention, firmly mounted to the wheelchair, enables the tie down straps


69


to secure the wheelchair to the vehicle floor.




The principle and mode of operation of this invention have been described in its preferred embodiments. However, it should be noted that this invention may be practiced otherwise than as specifically illustrated and described without departing from its scope.



Claims
  • 1. A wheelchair comprising:a base frame having a longitudinal axis, and a forward end and a rearward end joined by a first side frame and a second side frame, each side frame being generally parallel to the longitudinal axis; a first motor and a second motor, the first and second motors having a drive gear for rotating a drive wheel; and a first mounting bracket affixed directly to the first side frame and a second mounting bracket affixed directly to the second side frame, the first and second mounting brackets having a main body including a motor gear bore for receiving the drive gear, a front tie down point directed toward the forward end of the base frame, and a rear tie down point directed toward the rearward end of the base frame.
  • 2. The wheelchair according to claim 1, wherein the main body, the front tie down point, and the rear tie down point are all positioned in a single plane.
  • 3. The wheelchair according to claim 1, wherein the main body and the front tie down point are positioned in a first plane, and the rear tie down point is positioned in a second plane spaced apart from and generally parallel to the first plane.
  • 4. The wheelchair according to claim 1, wherein the front tie down point is located on a front extension of the main body and the rear fie down point is located on a rear extension of the main body.
  • 5. The wheelchair according to claim 1, whereinthe first bracket and the second bracket are configured so that when affixed to the first and second side frames, respectively, the rear tie down point on the first bracket and the rear tie down point on the second bracket are closer to each other than the front tie down point on the first bracket and the front tie down point on the second bracket.
  • 6. The wheelchair according to claim 1 wherein the brackets are generally vertically oriented in planes generally parallel to the longitudinal axis.
  • 7. A wheelchair comprising:a base frame having a longitudinal axis, and a forward end and a rearward end joined by a first side frame and a second side frame, each side frame being generally parallel to the longitudinal axis; a first motor and a second motor, the first and second motors having a drive gear for rotating a drive wheel; and a first mounting bracket affixed directly to the first side frame and a second mounting bracket affixed directly to the second side frame, the first and second mounting brackets being generally vertically oriented in planes generally parallel to the longitudinal axis, and having a main body including a motor gear bore for receiving the drive gear, a front tie down point directed toward the forward end of the base frame, and a rear tie down point directed toward the rearward end of the base frame.
US Referenced Citations (21)
Number Name Date Kind
2948253 Coonrod Aug 1960
4103934 Arnholt et al. Aug 1978
4147318 McDonald Apr 1979
4257644 Stephens Mar 1981
4389056 Tenniswood Jun 1983
4427210 Wevers Jan 1984
4455046 Linderoth Jun 1984
4492403 Blomgren et al. Jan 1985
4688843 Hall Aug 1987
4690364 Constantin Sep 1987
4826193 Davis May 1989
4934722 Goetzelman Jun 1990
4973022 Mayland Nov 1990
5026225 McIntyre Jun 1991
5044847 Saunders et al. Sep 1991
5186269 Avakian et al. Feb 1993
5391030 Lee Feb 1995
5431524 Antal et al. Jul 1995
5823723 Finch Oct 1998
5888038 Ditch et al. Mar 1999
5944131 Schaffner et al. Aug 1999
Non-Patent Literature Citations (3)
Entry
ANSI/RESNA WC/19 Standards for Wheelchairs Used as Seats in Motor Vehicles, pp. 9 and 10, published Oct. 1997.
SAE J2249 Wheelchair Tiedown and Occupant Restraint Systems for use in Motor Vehicles, p. 42, published Oct. 1996.
ISO/CD Proposed Standards 7176/ 19-1, Annex D, Specifications for Strap-Type Securement Points on Wheelchairs, p. 22, published Jule 1997.