Powered wheelchair having drive motors integrated into driven wheels

Abstract: Provided is a powered wheelchair (A) having the drive motors (60) mounted to the driven wheels (44). The wheelchair includes a seat (B) and first and second side frames (16) extending in a parallel relationship to support opposite sides of the seat. First and second driven wheels (44) are rotatably mounted on the first and second side frames through a fixed axle shaft (92). First and second drive motors (60) are fixedly mounted on the first and second driven wheels (14), respectively, and are operatively connected by first and second drives (80, 84, 88) to the first and second driven wheels, respectively. Rotation of the first and second drive motors causes rotation of the driven wheels. Control of the motors is provided by a remote control arrangement, the transmitter (100) being mounted to one of the side frames and the receiver (106) being mounted on the rotatably mounted wheels.

Description: This invention pertains to the art of wheelchairs, and more particularly to powered wheelchairs. The invention is particularly applicable to battery powered wheelchairs, and will be described with particular reference thereto. It will be appreciated that the invention has broader applications and may be advantageously employed in related powered wheelchairs and not restricted to the particular embodiment described. Present day wheelchair manufacturers employ substantially similar drive mechanisms for battery powered wheelchairs. Specifically, suitable connections are made between the battery and first and second drive motors. The drive motors are generally attached to the frame underneath or immediately behind the seat. They are positioned generally parallel to side frames of the wheelchair. That is, output shafts of the drive motors are disposed substantially parallel to the side frames. The driven wheels of the powered wheelchair are oriented for rotation in planes generally parallel to the side frames, i.e., rotation about axes substantially perpendicular to the side frames. It has been known to mount the drive motors transversely with respect to the side frames. Such an arrangement greatly restricts, however, the ability to collapse the wheelchair. A primary reason for the "parallel" mounting of the drive motors (i.e. parallel to the side frames) is the development of powered wheelchairs as evolved from motorizing non-powered, collapsible wheelchairs. The non-powered or manual wheelchairs had developed to a stage in which the folded or collapsible nature was heavily emphasized for transport and storage reasons. Adapting drive motors to these wheelchairs generally restricted the drive motors to a parallel mounting arrangement because of the collapsible nature of the wheelchair. The wheelchair manufacturers became accustomed to this original mounting arrangement and generally have continued to construct powered wheelchairs in a parallel mounting arrangement of the drive motors. It is believed that another reason for this parallel mounting arrangement of the drive motors is aesthetics. That is, the drive motors may be effectively "hidden" by mounting the motors under the seat in a parallel arrangement with the side frames. Also, in limited situations, this arrangement of the drive motors would still permit partial collapsing of the wheelchair to increase the ease of transportation. However, maximum collapsing of the wheelchair to improve the ease of transportation is not effectively accomplished by the known methods of mounting the drive motors. The typical powered wheelchair carries a battery. A rigid platform extends between the side frames to support the battery. Therefore, to fully collapse the wheelchair the battery and platform would have to be removed from the wheelchair. Thus, to improve the collapsible nature of the wheelchair and therefore improve the ease with which powered wheelchairs can be transported, it would be desirable to remove the motors from their normal parallel arrangement and remove the batteries and rigid platform which extends between the side frames. Patent specification US-A-3,908,776 discloses an attempt to remove the motors from beneath the wheelchair seat area. Two electric motor units are wholly disposed in the interior of the hub of the rear wheels of the wheelchair and are positioned to respective opposite sides of the axis of rotation of the wheel. Two driving gearwheels which are rotated by the respective motor units are engagable with an annular plate. Thus, gears of the stationary motors located within the wheel hub rotate the rear wheels by engaging the annular plate. The description further discloses that a battery tray and batteries carried thereby are used, but that they have been omitted in the Figures. Thus, even with the wheel hub mounting of the motors, the batteries still are located between the wheels, thereby obstructing maximum collapse of the wheelchair. Patent specification US-A-4 140 192 discloses a wheelchair with side frames each of which carries a drive motor and battery support tray forming a self-contained assembly that assists folding of the wheelchair, the respective side wheel being driven from the side frame mounted motor by a suitable gear transmission. According to one aspect of the invention, there is provided a powered wheelchair comprising: a seat; first and second side frames extending in spaced, generally parallel relationship and supporting opposite sides of the seat; first and second driven wheels rotatably mounted on the first and second side frames through a fixed axle shaft means, respectively, and for rotation relative thereto; and, first and second drive motors fixedly mounted on the first and second driven wheels, respectively, operatively connected by first and second drive means to the first and second driven wheels, respectively, whereby operation of first and second drive motors causes rotation of the first and second driven wheels, which in turn causes the first and second drive motors to be rotated in a circumferential path. Thus the motors being mounted fixedly in the wheels move each in a respective circumferential path as the wheel rotates. According to another aspect of the invention, there is provided a method of operating a powered wheelchair comprising the steps of: transmitting signals from a remote control transmitter means mounted to a frame of the wheelchair in a location at which the remote control transmitter means is operable by a person located in the wheelchair; receiving the transmitted signals by first and second remote control receiver means, respectively, mounted on first and second driven wheels, the driven wheels being rotatably mounted on the frame through a fixed axle shaft means; adjusting outputs of first and second motor control means based on the received signals, the first and second motor control means being mounted on the first and second driven wheels, respectively, and operatively connected to the receiver means; operating first and second drive motors, which are fixedly mounted on the first and second wheels, according to the outputs of the first and second motor control means, driving first and second drive gears with output shafts of the first and second drive motors, respectively; and engaging first and second fixed gears with the driven first and second drive gears, the fixed gears being fixed to the fixed axle shaft means, whereby the driving first and second drive gears rotate around the fixed gears thereby causing the first and second drive motors to be rotated in a circumferential path as the first and second drive motors rotate the first and second driven wheels. Providing the driven wheels to be driven by motors mounted on the driven wheels can increase the collapsible range of the powered wheelchair. Mounting the batteries, used to drive the drive motors, onto the driven wheels can further maximize the collapsible range of the powered wheelchair. By providing remote control of the driving motors the batteries and driving motors can be fully enclosed within the respective driven wheels. The provision of wheel mounted motors allows batteries to be mounted in a fixed manner around the wheel circumference to equally distribute weight around the circumference of the wheel, thereby providing balanced overall driven wheels. The invention is diagrammatically illustrated by way of example in the accompanying drawings, in which: Figures 1A and 1B are side and rear perspective views of a powered wheelchair according to the invention; Figures 2A and 2B are front and side perspective views of a single wheel of the wheelchair of the present invention; Figure 2C is a side perspective view of a single wheel of the wheelchair of the present invention, in an alternative embodiment; and Figure 3 is a block diagram for the control arrangement of the present invention. Referring now to the drawings, wherein the showings are for purposes of illustrating the preferred embodiment of the invention only and not for purposes of limiting same, the FIGURES show a battery powered wheelchair A including a seat assembly B , frame assembly C , a remote control arrangement D , and a driven wheel arrangement E . More particularly, as disclosed in FIGURE 1A, the powered wheelchair seat assembly B is defined by a first or bottom seat portion 10 and a second or seat back portion 12 . The seat assembly is commonly constructed from a padded vinyl material that is secured along peripheral edges of the frame assembly C . Still further, seat inserts may also be utilized with this type of construction to readily conform to the body shape of a particular user. The frame assembly C is defined by a pair of side frames 16 . The side frames are substantially identical in construction so that description of one is equally applicable for the other unless specifically noted otherwise. For example and with reference to side frame 16 , first, second, and third vertical frame members 20, 22, 24 are secured in spaced relation by first and second horizontal members 28, 30 . A cross-brace frame structure (See FIGURE 1B) is disposed to maintain the first and second side frame assemblies 16 in spaced, generally parallel relationship. Support members 32 are received on the side frame assemblies. Extending upwardly from the third vertical member 24 are rear canes 36 that facilitate manual movement of the wheelchair. The frame assembly is preferably formed from tubular members that are welded or otherwise secured together. The frame arrangement provides a lightweight yet durable arrangement that readily receives additional components thereon for adapting the wheelchair to specialized needs of a particular user. A footrest assembly 40 may also be secured to the first vertical member of each side frame. Since footrest assemblies of this type are commonly known and do not form a specific part of the subject invention, further discussion is deemed unnecessary. First and second driven rear wheels 44 are secured to the side frames 16 in a manner that facilitates rotation. Conventional bearing assemblies provide for ease of rotation of each wheel 44 relative to its respective side frame. Disposed forwardly from the first and second driven wheels are a pair of caster wheels 48 of substantially smaller diameter. The small diameter caster wheels are secured to respective side frames through swivel mountings 52 which permit rotation through 360°. The small diameter caster wheels easily pivot in response to the drive torque applied to the driven wheels. Mounted to spokes 47 of the driven wheels 44 are the drive motors 60 , batteries 64 , and RF receiver/motor control modules 68. The RF receiver portion of modules 68 receives signals from an RF transmitter of a controller 72 located on one of the side frames 16 at a position wherein a person positioned in seat portion 10 can operate the controller 72 . The operation of radio receivers and transmitters is well-known and need not be explained in detail here. Briefly, an antenna which picks up the radio waves from the transmitter is coupled to the input of an RF amplifier in the receiver. The output of the RF amplifier is applied to an electronic component called a mixer which is also connected to an oscillator. The mixer then "mixes" the RF signal from the RF amplifier with the oscillating signal from the oscillator to produce an output signal of a lower intermediate frequency. This lower intermediate frequency signal is then fed to an intermediate frequency amplifier, and that amplified signal is then applied to an electronic component known as a discriminator which in turn produces an output voltage that is then fed to a relay, to energize an operatively connected device such as a motor controller. In this manner, an attached motor control circuit then functions in response to signals transmitted by the transmitter to the receiver. As shown in FIGURE 1B, cross bars 56 of the cross-brace frame structure interconnect side frames 16 in a parallel spaced relationship. The cross bars 56 are collapsible, having a hinge 58 included therein. Collapsing of hinge 58 facilitates collapsing the entire wheelchair for transportation or storage. With attention to FIGURES 2A and 2B, a more detailed description of the operation of the driven wheels 44 will be had. It is to be appreciated that the description set forth in the following Figures is appropriate for both first and second driven wheels 44. As shown in FIGURE 2A, three similarly constructed batteries 64 are positioned in spaced relationship to each other along with the drive motor 60 and RF receiver/control module 68 such that the weight of these devices are evenly distributed throughout the circumference of the driven wheels 44. The drive motors may be "pancake" type motors in a preferred embodiment. Such motors have a relatively thin cross-section or profile. It is to be appreciated however, that other motors may be successfully implemented in the present invention. While in the embodiment of FIGURE 1A, the drive motors 60 are mounted to the spokes 47 of the driven wheels 44, it is to be appreciated that other attachment arrangements are possible. In particular, as shown in FIGURE 2A, the driven wheels 44 have wheel covers 59, and, if the wheel covers are fixedly attached to the wheels, the drive motors 60 can be attached to such wheel covers 59 . This is also true for the batteries 64 and RF receiver/control modules 68 which are also integrated into the wheels. With continuing attention to FIGURE 2A, the output shaft 80 of the drive motor 60 engages rotatable drive gear 84. The rotatable drive gear 84 then engages fixed gear 88 . The fixed gear is attached to fixed axle shaft 92. This arrangement causes the rotatable drive gear 84 to rotate around the fixed gear 88 in a planetary fashion when the output shaft 80 of the drive motor 60 is rotating, thus rotating the driven wheel 44 . This type of rotation can be accomplished by use of a planetary gear box. As the drive gear rotates around the fixed gear, the drive motor 60 which is mounted on spokes 47 or wheel covers 59 of the driven wheel is rotated in a circumferential path causing rotation of the driven wheel 44. Another view of the above-discussed arrangement is set forth in FIGURE 2B. As is more clearly shown in this Figure, each driven wheel 44 is rotatably attached to the fixed axle shaft 92 through the use of bearings 96 allowing the driven wheel 44 to rotate around the fixed shaft 92 . As is also more clearly shown in this Figure, the drive motor is fixedly mounted substantially parallel to the driven wheel 44 such that the output shaft 80 is substantially perpendicular to the driven wheel 44. The output shaft of the drive motor drives the drive gear 84. The drive gear engages the fixed gear 88 which is fixedly connected to the stationary axle shaft 92. Again, in this arrangement the drive gear 84 rotates around the fixed gear 88 which causes rotation of the driven wheel 44. As shown in FIGURE 2C another embodiment of the present invention includes attaching each drive motor 60 such that the drive shaft 80 is perpendicular to the fixed axle shaft 92 . In this embodiment to translate rotation of the drive shaft 80 to the fixed axle shaft 92 , a right angle gear box 94 is interposed into the gearing arrangement as shown in FIGURE 2C. It is to be appreciated that while FIGURES 2B and 2C show the motors 60 mounted such that they extend outside of the profile of the driven wheels 44, they can be mounted entirely within the driven wheel profile. Using the above disclosed arrangements, incorporating the drive and control means into the driven wheels, there is no footprint of the drive motors, batteries, or controller between the driven wheels of the wheelchair. This, therefore, allows for a maximum collapsing of the wheelchair. With attention to FIGURE 3, a block diagram is detailed setting forth the use of RF controlled transmitters and receivers. The controller 72 includes RF transmitter 100 and joystick 102 . The joystick is operable by a person positioned within the wheelchair. The controller 72 is powered by battery 104 . Operation of the joystick provides output signals to be transmitted by the RF transmitter 100 . The output signals are received by the RF receiver/motor control modules 68 . The modules include RF receiver and control interface circuitry 106 and proportional motor controllers 110 . The RF receivers and proportional motor controllers along with the driven motors 60 are powered by batteries 64. As is well-known, regulating the power supply to right and left drive motors controls the output torque for driving the wheels. If equal power is supplied to the drive motors, the wheelchair will move forwardly and rearwardly, generally in a straight path. Reducing the power to a selected motor causes the wheelchair to turn. The motors may also be selectively driven in reverse to facilitate turning, if desired. The electronics in the proportional motor controllers 110 are considered well-known in the art so that further discussion is deemed unnecessary to a full and complete understanding of the subject invention. Though the present wheelchair is a motorized wheelchair, it is to be appreciated that the wheelchair may be manually moved both forwardly and rearwardly even though the drive mechanism is fully engaged. As is conventionally known, clutch mechanisms may be incorporated adjacent the drive gears to selectively engage and disengage the drive mechanisms from the rotary output of the drive motors. Any number of clutch arrangements could be utilized within the scope of the present invention.

Claims: A powered wheelchair comprising: a seat (10,11); first and second side frames (16) extending in spaced, generally parallel relationship and supporting opposite sides of the seat (10,11); first and second driven wheels (44) rotatably mounted on the first and second side frames (16) through a fixed axle shaft means (92), respectively, and for rotation relative thereto; and, first and second drive motors (60) fixedly mounted on the first and second driven wheels (44), respectively, operatively connected by first and second drive means (84,88) to the first and second driven wheels (44), respectively, whereby operation of first and second drive motors (60) causes rotation of the first and second driven wheels (44), which in turn causes the first and second drive motors (60) to be rotated in a circumferential path. A powered wheelchair according to claim 1, further comprising: remote control transmitting means (72) for transmitting signals for use in controlling operation of the first and second drive motors (60), the transmitting means (72) being mounted to at least one of the first and second side frames (16), whereby a person located in the seat (10,12) can operate the transmitting means (72); and, first and second remote control receiving means (68) for receiving the transmitted signals, the receiving means (68) being mounted on the first and second driven wheels (44), respectively, and operatively connected to the first and second drive motors (60), respectively. A powered wheelchair according to claim 1 or claim 2, wherein the interiors of each of the first and second driven wheels (44) are enclosed, whereby the mounted first and second drive motors (60) are enclosed. A powered wheelchair according to any one of claims 1 to 3, wherein the first and second drive motors (60) are powered by first and second battery means (64), respectively, the first and second battery means (64) being mounted to the first and second driven wheels (44), respectively. A powered wheelchair according to any one of claims 2 and 4, wherein the first drive motor (44), battery means (64), and receiver means (68) are mounted on the first driven wheel (44) in spaced relationship to provide approximately equivalent weight to each portion of the first driven wheel (44). A powered wheelchair according to any preceding claim, wherein the first and second drive motors (60) are pancake type motors having a low profile. A powered wheelchair according to any preceding claim, wherein the first and second drive motors (60) are mounted to spokes (47) extending radially from a respective hub of the first and second driven wheels (44), respectively. A powered wheelchair according to any preceding claim, wherein the first and second drive motors (60) are mounted to wheel covers (97) fixedly attached to the driven wheels. A powered wheelchair according to claim 1, wherein the first and second drive motors (60) are mounted substantially parallel to the first and second driven wheels (44), whereby first and second output shafts (80)of the respective motors (60) are substantially perpendicular to the first and second driven wheels (44), the output shafts (80) of the drive motors (60) driving first and second drive gears (84) of the first and second drive means, the first and second drive gears (84) engaging first and second fixed gears (88), respectively and the first and second fixed gears (88) being fixedly connected to the fixed axle shaft means (92). A powered wheelchair according to claim 9, further including a remote control means (72) for remotely controlling operation of the drive motors (60). A powered wheelchair according to claim 8 or claim 9, wherein the first and second drive motors (60) are mounted to the fixed axle shaft means (92), whereby rotation of the first and second drive motors (60) causes planetary rotation of the first and second drive gears (84,88) in relation to the first and second drive motors (60). A powered wheelchair according to claim 1, comprising first and second motor control means (110) respectively mounted to the first and second driven wheels (44) and operatively connected to the first and second drive motors (60), respectively, whereby operation of the first and second motors (60) can be controlled; first and second remote control receiver means (106) mounted to the first and second driven wheels (44), respectively, and operatively connected to the first and second motor control means (110), respectively; and a remote control transmitter means (100) mounted to at least one of the first and second side frames (16) so as to be operable by a person located in the seat (10,12), whereby signals from the remote control transmitter can be transmitted to and received by the first and second remote control receiver means (106). A powered wheelchair according to claim 12, wherein the interiors of each of the first and second driven wheels (44) are enclosed, whereby the mounted first and second drive motors (60) are enclosed. A powered wheelchair according to claim 12 or claim 13, further including hinged cross-braces (56) whereby disengagement of the hinged cross-braces (56) allows collapsing of the wheelchair. A remote controlled powered wheelchair according to any one of claims 12 to 14, wherein the first and second output shafts (80) of the first and second drive motors (60) are substantially perpendicular to the axle shaft means (92). A method of operating a powered wheelchair comprising the steps of: transmitting signals from a remote control transmitter means (72) mounted to a frame (16) of the wheelchair in a location at which the remote control transmitter means (72) is operable by a person located in the wheelchair; receiving the transmitted signals by first and second remote control receiver means (106), respectively, mounted on first and second driven wheels (44), the driven wheels (44) being rotatably mounted on the frame (16) through a fixed axle shaft means (92); adjusting outputs of first and second motor control means (110) based on the received signals, the first and second motor control means (110) being mounted on the first and second driven wheels (44), respectively, and operatively connected to the receiver means (106); operating first and second drive motors (60), which are fixedly mounted on the first and second wheels (44), according to the outputs of the first and second motor control means (110), driving first and second drive gears (84) with output shafts (80) of the first and second drive motors (60), respectively; and engaging first and second fixed gears (88) with the driven first and second drive gears (84), the fixed gears (88) being fixed to the fixed axle shaft means (92), whereby the driving first and second drive gears (84) rotate around the fixed gears (88) thereby causing the first and second drive motors (44) to be rotated in a circumferential path as the first and second drive motors (60) rotate the first and second driven wheels (44). A method of operating a powered wheelchair according to claim 16, wherein the steps of transmitting and receiving signals are accomplished by radio frequencies.

Inventors: RICHEY JOSEPH B, RICHEY, JOSEPH B.
Applicants: INVACARE CORP, INVACARE CORPORATION
Application year: 1993
Main classification: A61G5
IPC codes: A61G5