Patent Application
20170151108
The invention generally relates to medical devices. In particular, this invention relates to manually propelled wheelchairs.
There are an estimated 1.5 million manual wheelchair users (mWCUs) in the United States, and an estimated 200 million wheelchair users worldwide. Manual wheelchair users depend on their upper limbs for mobility and activities of daily living. However, up to 70% of manual wheelchair users report shoulder pain. Shoulder pain in mWCUs has been directly linked to further disability including difficulty performing activities of daily living, decreased physical activity, and reduced quality of life. Overall, any loss of upper limb function due to pain adversely impacts the independence and mobility of mWCUs. Thus, it is imperative to provide innovative technologies, therapies, and interventions to minimize shoulder pain.
Additionally, some wheelchair users may already have diminished strength in their upper limbs. The magnitude of diminishment can make use of a traditional manual wheelchair, with the torque necessary to move up hills in particular, unduly difficult and impracticable. Thus, there is a need for a manual wheelchair to accommodate wheelchair users with diminished strength of their upper limbs.
Using a powered wheelchair takes away all strain on the shoulders and reduces shoulder pain. However, powered chairs are not a viable option for most wheelchair users, because they are expensive, heavy (i.e., too heavy to load into a car, requiring special vans and lifts), have limited use duration due to battery life, require frequent recharging, provide little flexibility for persons who are capable of manually propelling their own chair, are sometimes too wide to fit through doorways, and contribute to reduced physical fitness due to limited upper body movement. Additionally, there is often a negative stigma attached to the use of these devices among manual wheelchair users. Most manual wheelchair users would never utilize a powered wheelchair unless it was their last option.
In order to address this large segment of the community that experiences difficulty pushing a wheelchair, various designs have been provided in the art. Examples include power assist wheelchairs, lever operated wheelchairs, and manually gear shifting wheelchairs. Push-rim activated power assist wheelchairs (PAPAWs) were one of the first technologies that addressed this need. They are similar to power wheelchairs, but batteries and motors in the wheel hubs assist the user to push his/her chair. These devices have been shown to significantly reduce the amount of energy used by an mWCU. However, PAPAWs are not ideal since they are heavy (e.g., 53 lbs of added weight) and more difficult to maneuver than a manual wheelchair, as they require two large electric motors and a battery. Also, the range of such devices is limited before the battery needs recharged. Further, these devices are quite expensive, e.g., more than an entry level powered chair, and the price does not include the cost of a wheelchair frame.
Lever operated wheelchairs are an innovative way to utilize a more ergonomic rowing motion from the wheelchair user. An example lever operated wheelchair is provided in an add-on device from Wijit Wheelchairs (Roseville, Calif.). Evaluation of these devices has shown that levers are a more comfortable method of propulsion, and they reduce the amount of work from the shoulders. However, these devices do not follow the concept of a traditional wheelchair design; that is, use of hand rims. Such wheelchairs accordingly require a relatively high learning curve to switch between forward and reverse propulsion. With an unintuitive method for current manual wheelchair users of braking and pushing in reverse, these devices have been very slow to catch on.
Magic Wheels (Seattle, Wash.) created a two-speed wheelchair add-on system in which the second gear is specifically catered for going uphill. In a clinical trial using this device, subjects experienced a significant reduction in the severity of shoulder pain. However, a limitation is that the user has to stop and manually shift into the other gear, e.g., physically turn a dial on the side of the wheel to shift. For many wheelchair users who have limited dexterity in their hands (e.g., due to spinal cord injury), it is physically impossible to turn this dial. Further, users have to be cognizant of when to shift, and thus individuals with cognitive deficits such as traumatic brain injury, dementia, etc., are unable to utilize such a device.
There is a need in the art for a suitable device that fits in between manual and powered wheelchairs.
Provided herein are methods, systems, and apparatuses for a geared wheel system for minimizing backlash comprising: a geared hub operably coupled to a hand rim support structure and a plurality of spokes; the hand rim support structure operably coupled to a wheel rim and the plurality of spokes operably connected to the wheels; and wherein the geared wheels are shifted from a direct drive transmission to a low gear drive transmission by a lever operably coupled on the outside of each hub.
The methods, systems, and apparatuses are set forth in part in the description which follows, and in part will be obvious from the description, or can be learned by practice of the methods, apparatuses, and systems. The advantages of the methods, apparatuses, and systems will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the methods, apparatuses, and systems, as claimed.
In the accompanying figures, like elements are identified by like reference numerals among the several preferred embodiments of the present invention.
The foregoing and other features and advantages of the invention are apparent from the following detailed description of some embodiments, read in conjunction with the accompanying drawings. The detailed description and drawings are merely illustrative of the invention rather than limiting, the scope of the invention being defined by the appended claims and equivalents thereof.
The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context.
Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. The word “about,” when accompanying a numerical value, is to be construed as indicating a deviation of up to and inclusive of 10% from the stated numerical value. The use of any and all examples, or exemplary language (“e.g.” or “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any nonclaimed element as essential to the practice of the invention.
References to “one embodiment,” “an embodiment,” “example embodiment,” “various embodiments,” etc., may indicate that the embodiment(s) of the invention so described may include a particular feature, structure, or characteristic, but not every embodiment necessarily includes the particular feature, structure, or characteristic. Further, repeated use of the phrase “in one embodiment,” or “in an exemplary embodiment,” do not necessarily refer to the same embodiment, although they may.
Generally speaking, the embodiments disclosed herein provide a single low-gear system for manually propelled wheelchairs. As opposed to standard manual wheelchairs having the hand rim directly attached to the wheel, the embodiments disclosed herein provide a single low-gear system where the hand rim turns the input of the low-gear system and the wheel is turned by the output of the low-gear system. In some embodiments, the input of the low-gear system may be coupled to any drive power source, such as a motor, a lever assembly, the hand rim, and/or the like.
In operation of a preferred embodiment, the wheelchair user still pushes the hand rims forward, backward, and in opposite directions in order to turn; however, the hand rims drive the low-gear systems (located near the hub of each wheel), which in turn drive the wheels. This reduces the amount of force required from the wheelchair user, which has the potential to reduce the severity and incidence of shoulder pain for mWCUs.
In contrast to motor driven wheelchairs in the art, example systems of the preferred embodiments disclosed herein do not have a range that is limited by battery life. Further, an example system weighs less than 10 lbs additional to the wheelchair. In contrast to lever operated wheelchairs, the preferred embodiments disclosed herein retain the standard hand rim method of controlling the wheelchair. The system provides for the operator of a traditional arm-powered wheelchair to make use of the wheelchair with little or no injury to the shoulder of the operator by reducing the force required to move the wheelchair. The input of the system is coupled to the hand rim, and the output is coupled to the wheel. Through use and configuration of gear systems, including planetary gear systems, the rotational velocity of the hand rim relative to the wheel can be increased or decreased, as the design provides. The system can include a ring gear, one or more sun gears, a planet carrier, one or more planet gears, and a mounting assembly for mounting the system to the wheelchair. The ring gear, sun gears, and planet carrier can be either fixedly attached or rotatably coupled to the axle of the system or the wheel or hand rim of the wheelchair to achieve the desired rotational ratio between the hand rim and the wheel.
A detailed description of the embodiments disclosed herein is provided in the following pages. It will be appreciated that these pages provide detail regarding the embodiments disclosed herein, and the invention is not limited to these embodiments or details. While embodiments disclosed herein are shown and described, it should be understood that other modifications, substitutions, and alternatives are apparent to one of ordinary skill in the art. Such modifications, substitutions, and alternatives can be made without departing from the spirit and scope of the invention.
In one embodiment, the low-gear system is attached to the outside of each of the two wheels 216 of a wheelchair apparatus 100, as shown in
The embodiments disclosed herein include low-gear systems based on many different types of gear drive systems including, but not limited to, planetary gear sets, complex planetary gear sets, hypocycloidal gear sets, beveled gear sets, helical gear sets, traditional gear sets, and traditional gear sets in which multiple gears rotate on multiple axes of rotation.
While all types of gearing systems are included in the embodiments disclosed herein, one preferred embodiment of a low-gear drive system is described in relation to
The low-gear system 200 further comprises at least one planet gear 212 and a planet carrier 214. The planet gears 212 can constantly mesh with both the sun gear 208 and the ring gear 202. In the present embodiment, the low-gear system 200 comprises three planet gears 212; three or more planet gears 212 will maintain the collinearity of the axes of rotation of the ring gear 202 and the sun gear 208.
The planet carrier 214 further comprises one or more planet posts 224 projecting from the second surface 220 of the body member 218. Preferably, the planet posts 224 are integral with the body member 218. As shown in
The planet carrier 214 can then be fixedly attached to the wheel 216. The method of attachment depends upon the structure of the wheel. The wheel 216 as depicted in
Other methods for securing the planet carrier 214 to the wheel 216 are within the scope of the embodiments disclosed herein. Other methods include threaded couplings, keyed shafts, welding, set screws, nuts and/or bolts, any shape in which the two can engage with each other, and combining the wheel 216 and the planet carrier 214 as one integral part. These and any other method of securing the planet carrier 214 to the wheel 216 are included in the scope of the embodiments disclosed herein.
The low-gear system 200 can further comprise a planet retainer plate 228, as shown in
A view of the embodiment illustrated in
Other methods of preventing rotation of the axle 210 are within the scope of the embodiments disclosed herein, such as lock washers, a keyed shaft, shaft collars, welding the axle directly to the frame, or any other method. One such example of a method for preventing the axle from rotating is depicted in
In this particular embodiment, the quick release assembly 303 also serves to allow the wheels 216 to be quickly attached or detached from the frame 231. By flipping the lever 306 of the binder bolt 307 to a down position as shown in
In order to provide easy handling, the planet retainer plate 228 can be shaped in a way that allows it to be grasped with a single hand. The planet retainer plate 228 therefore features a handle 308, as shown in
In order to decrease wear on the gear teeth, decrease gear noise, and increase the smoothness of operation, ball bearing tracks 309 can be formed into the sun gear 208, the planet retainer plate 228, the planet carrier 214, and the ring gear 202, as shown in
In operation, a user rotates the hand rim 227. The power imparted by the rotation will be transmitted through the plurality of spokes 204 or the formed disk 310 to the ring gear 202, causing the ring gear 202 to rotate. The rotation of the ring gear 202 will cause the planet gears 212 to rotate by the meshing engagement therebetween. Owing to the sun gear 208 being fixedly attached to the axle 210, the planet gears 212 will also rotate with respect to the axis of rotation 206. The rotation of the planet gears 212 about the axis of rotation 206 will rotate the planet carrier 214 as well as the wheel 216 to which the planet carrier 214 is engaged. By adjusting the sizes of the ring gear 202, the sun gear 208, the planet gears 212, and the planet carrier 214, the low-gear system will enable the hand rim 227 to rotate at a different angular velocity than the wheel 216. The low-gear system 200 can be configured to allow the hand rim 227 to rotate at an angular velocity greater or less than that of the wheel 216, whichever is desired for a given application.
With the embodiment previously described, the gear ratios that are possible include any ratio greater than 1:1 but less than 2:1. The ratio is changed by altering the size of the planet gears with respect to the size of the sun gear. As the size of the planet gear decreases, the gear ratio increases. If the ring gear is connected to the wheel and the planet carrier is attached to the hand rim, a high gear system is achieved where the gear ratios are exactly reversed. In this variation of the above embodiments, the gear ratios that are possible include any gear ratio greater than 1:2 but less than 1:1.
In an alternative embodiment, the planet carrier 214 is fixedly attached to the hand rim 227 and the ring gear 202 is fixedly attached to the wheel 216, as shown in
A further embodiment of the invention disclosed herein is depicted in
The planet carrier 512 includes a first surface 512a and a second surface 512b, whereby the first sun gear 502 is rotatably associated with the first surface 512a and the second sun gear 506 is rotatably associated with the second surface 506. The first planet gear 508 is rotatably coupled to the first surface 512a of the planet carrier 512 and the second planet gear 510 can be rotatably coupled to the second surface 512b of the planet carrier 512. In the present embodiment, the first planet gear 508 and the second planet gear 510 are coupled via a planet attachment assembly 513 comprising a planet post 514 and a ball bearing 516. The first planet gear 508 and the second planet gear 510 can be rotatably attached to the planet post 514 by any suitable method, including welding, keys, ground flats, set screws, and any other method known in the art. In order to accommodate the ball bearing 516, the planet carrier 512 can include an aperture configured to allow the ball bearing 516 to be disposed therein. The ball bearing 516 can be fixedly attached to the planet carrier 512 by any suitable method, such as by welding or press fit. The planet post 514 can then be attached to the ball bearing 516 such that the planet post 514, and by extension the first planet gear 508 and the second planet gear 510, can rotate with respect to the planet carrier 512.
The second sun gear 506 can be fixedly attached to the wheel by any method of attachment described hereinabove for attachment to the wheel 216. For example, second sun gear 506 can comprise a plurality of protrusions 518 projecting from a surface 506a of the second sun gear 506. The plurality of protrusions 518 can radially extend around a central cup 519 and the protrusions 518 can be configured to form a plurality of slots 520 intermediate each of the protrusions 518. Similar to the method of attachment of the planet carrier 214 to the wheel 216 above, the plurality of slots 520 can be configured to be associated and fixedly engage with the spokes 217 of the wheel 216 (not pictured) so as to prevent the second sun gear 506 from rotating with respect to the wheel 216. Accordingly, rotation of the second sun gear 506 cases rotation of the spokes 217 of the wheel 216. Similarly, the planet carrier 512 can be fixedly attached to the spokes 204 of the hand rim 227 by any method described hereinabove for attachment to the wheel 216. Alternatively, the planet carrier 512 is coaxially fixed within an inner diameter of the hand rim 227 by means of a formed disk 310 or a plurality of spokes 204.
In an alternative embodiment, the planet carrier 512 can be fixedly attached to the wheel 216, while the first sun gear 502 and the second sun gear 506 can be fixedly attached to the hand rim 227. The first sun gear 502 and second sun gear 506 can be fixedly attached to the hand rim 227 by any of the methods described hereinabove, and the planet carrier 512 can be attached to the wheel 216 by any of the methods described hereinabove.
In further alternative embodiments, the planet carrier 512, the first sun gear 502, the second sun gear 506, and the pairs of first and second planet gears 508, 510 can be positioned in any order along the length of the axle 210. This includes configurations in which the first sun gear 502, the second sun gear, 506, and the pairs of first and second planet gears 508, 510 are on one side of the planet carrier 512.
Minimizing Backlash
As shown in
As shown in
The geared wheels 601 mount to the wheelchair 600 with a quick release axle 700 operably coupled with a custom mounting system 631, as shown in
In one embodiment, the gearing is completely encased in a metal geared hub 602, as shown in
Hand Rim Support Structure
The hand rim support structure 665, shown in
The hand rim support structure 665 comprises a plurality of radially extending hollow tubes 663 operably coupled with a molding 664. In one embodiment, the radially extending hollow tubes 663 are composed of extruded aluminum. In other embodiment, other lightweight metals or plastics may be used, such as die cast aluminum or magnesium. The molding 664 surrounds the plurality of radially extending hollow tubes 663, which bonds with the tubes 663 into the correct shape. In one embodiment, the molding 664 is a plastic molding, urethane, or a glass filled nylon. In one embodiment, the plastic molding is a minimum of 0.10 inch in thickness around the aluminum tubes, and there are relatively large thickness of plastic molding where the ends of the tubes 663 meet, with the purpose of increasing strength and increasing rigidity. In one embodiment, the shape of the tubes 663 is substantially curved. In one embodiment, the tubes 663 are curved with angle between about 10 and 85 degrees, alternatively, about 20 degrees. The middle portions of the tubes 663 and the molding 664 may include at least two openings 661 that permit the structure 665 to be fixedly attached to the input disk 613. In one embodiment, the number of tubes 663 is the same as the number of flanges 613 on the input disk 613. In one embodiment, the number of tubes 663 may be between about two and six.
Shift Lever
Many people with spinal cord injuries have limited hand dexterity. In order to shift gears effectively, the shifter must be easy to articulate without too much fine motor control. For this reason, the lever 622 includes a large flat section, as shown in
The lever 622 rotates in a track 639 and includes at least two flats 651, as shown in
Shifter Carriage Design
In one embodiment, the geared hub includes a planetary gear set. The planetary gear set is part of a shifter carriage 630 to allow the gear box to move between gears. The shifter carriage 630 comprises gear carrier 636, the ring gear 635, a first dog clutch 626 connected to the gear carrier 636, a second dog clutch 627 which carries the four planet gears 624, and two gear keepers 629 which link the ring gear 635 to the dog clutch while allowing independent rotation. 4 bushings 666 are attached to the gear carrier 636 through the first dog clutch 626. A sun gear 632 is not part of the shifter carriage. The sun gear 632 is always locked to the axle sleeve 621, and does not move axially or rotate.
The shifter carriage 630 rides axially along 4 dowel pins 650 extending from the input disk 613. The dowel pins 650 provide minimal backlash in the rotational direction while allowing the carriage 630 to move axially inside the hub. The bushings 666 are reamed out to a size slightly larger than the dowel pins 650 in order to minimize backlash while still allowing smooth movement. In one embodiment this corresponded to 0.1875″ DIA dowel pins 650 and 0.196″ inner DIA bushings 666. The dowel pins 650 and the bushings 666 that surround them have the added advantage that they are very resistant to mechanical wear which keeps the amount of backlash from increasing significantly over the life of the gearbox.
When the shifter carriage 230 moves from
When the shifter carriage 230 moves from
When the shifter carriage 630 is in position of
An alternate embodiment is shown in
An alternate embodiment shown in
Dog Clutch Design
The purpose of the dog clutches 625, 626, 627, 628 is to engage a gear with minimal backlash, in a small package, and at a minimal weight.
In one embodiment, the dog clutches are made from hardened steel for optimal wear resistance, and have minimal clearance between the teeth. The clearance is between about 0.002″ and 0.015″. In another embodiment, the dog clutches include teeth comprising 0, 0.5, 1, and 2 degree gaps between each tooth and corresponding slot. In one embodiment, a 0.5 degree gap is selected for easy engagement and low backlash. A 0.5 degree gap corresponds to 0.0153 inch clearance when measured at a diameter of 3.5 inches and that provides a positive tolerance you get a clearance range of about 0.015 inches and about 0.002 inches.
Shifter Rod Design
As shown in
The components in the geared hub 603, 604 can be in one of 3 positions: low gear, high gear, or neutral. Depending on the alignment of the teeth of the clutches, the clutches may not travel the full linear distance when shifting into a gear. The user would interpret that as the shifter being jammed. Therefore, the shift rod 618 is not rigidly connected to the shift disk 617. The shift rod 618 has springs 660 on either side of the shift disk 617 so that the shift rod 618 can move to its intended position regardless of the position of the clutch teeth. The springs 660 push on the shift disk 617 until the clutch teeth line up in the correct orientation, at which point the springs 660 push the shift disk 617 the remaining way and the dog clutch locks into full engagement.
Mounting System
The geared wheel 601 must have its axle sleeve 621 locked from rotating in order to ensure correct operation of the gears. To accomplish this, a mounting system 631 is used is shown in
While the invention has been described in connection with various embodiments, it will be understood that the invention is capable of further modifications. This application is intended to cover any variations, uses or adaptations of the invention following, in general, the principles of the invention, and including such departures from the present disclosure as, within the known and customary practice within the art to which the invention pertains.
| Number | Date | Country | |
|---|---|---|---|
| 61540768 | Sep 2011 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 13631088 | Sep 2012 | US |
| Child | 14958026 | US |
