This invention relates generally to land vehicles and more particularly to personal mobility vehicles. Most particularly, the invention relates to a personal mobility vehicle having a tiltable seat assembly.
Personal mobility vehicles with tilting seats are well known. Such vehicles are typically used in highly dependent or geriatric care, wherein the ability to reposition a vehicle occupant in various angular positions is beneficial to the occupant's health and daily routine. Tilting a vehicle occupant relieves pressure to the vehicle occupant's ischial tuberosities (i.e., the bony prominence of the buttocks). Continuous pressure to the vehicle occupant's ischial tuberosities, which is applied when the vehicle occupant remains in a single seated position, can cause the development of decubitus ulcers (i.e., pressure sores). For vehicle occupants with severe kyphosis (i.e., curvature of the spine), seated tilting may allow the occupant to look forward and interact with their surroundings. Tilting may also be beneficial to assist with proper respiration and digestion.
Some personal motor vehicle occupants require attendant care, wherein an attendant is responsible for positioning the vehicle seat angle, often changing the angle on a prescribed schedule. The ability to tilt the vehicle occupant offers the occupant a variety of positions that accommodate their daily schedule, including, for example, an anterior tilt for eating at a table and posterior tilt for resting.
Conventional tilting personal mobility vehicles consist of a seat frame that is pivotally mounted to a base frame so that the seat frame tilts to reposition the vehicle occupant. The pivot axis is typically mounted between the base frame and seat frame, towards the rear of the seat and away from the occupant's center of gravity. Tilting the occupant involves lifting or lowering his or her center of gravity and therefore requires effort on the part of the attendant. Mechanisms, such as springs or gas cylinders, are often employed to assist in tilting the occupant. Typically, levers are attached to handles on a seat-tilting vehicle. The levers allow an attendant to release a locking mechanism, change the tilt angle by pushing or pulling on the handles, and engage the locking mechanism, which fixes the tilt angle.
Tilting the seat in conventional tilt personal motor vehicles may invoke a reaction on the part of the occupant who experiences the sensation of being tipped over. The occupant experiences a sensation of being pitched off balance during tilting. Conventional tilt seat designs involve translation of the vehicle occupant's center of gravity during tilting. Significant effort on the part of the attendant may be required to tilt the vehicle occupant when the occupant's mass translates during tilting. Moreover, conventional vehicles with tilt seats require large base frames and anti-tip devices because tilting the chair displaces the occupant's center of gravity fore and aft over the wheelbase, potentially placing the vehicle off balance.
What is needed is a personal mobility vehicle that does not evoke the sensation of being tipped over; that requires minimal effort on the part of the attendant to tilt (i.e., no lifting or lowering of the vehicle occupant's center of gravity should be required to tilt the vehicle seat assembly); does not affect weight distribution between the front and rear wheels; and that is limited to pure rotation (i.e., the only effort required is to overcome friction within the system), thus eliminating the need for springs or gas cylinders to assist tilting.
The present invention is directed towards a personal mobility vehicle that overcomes the foregoing deficiencies. The vehicle comprises a base and a seat moveable along a curve having a focal point. The vehicle is adjustable to position an occupant in the seat to achieve a desired position for the center of gravity of the occupant relative to the focal point of the curve.
Another embodiment of the invention is directed to a personal mobility vehicle comprising a personal mobility vehicle having a seat that is supported for movement relative to a radial or quasi radial curve having a center of curvature that is preferably substantially fixed in space. The seat is adjustable with respect to the curve so that the center of gravity of a vehicle occupant is sufficiently coincident with the focal point of the curve so that force required to tilt the seat is minimized.
Another embodiment of the invention is directed to a personal mobility vehicle comprising a base and a seat for support a vehicle occupant. The seat is supported for movement along a curve having a center of curvature. The seat is adapted to support a vehicle occupant having a center of gravity that is adapted to be positioned relative to the center of curvature sufficient to minimize effort required to move the seat with the vehicle occupant therein along the curve.
Another embodiment of the invention is directed to a personal mobility vehicle comprising a base, a plurality of wheels that are adapted to support the base relative to a supporting surface, and a seat for supporting an occupant. The seat is supported relative to the base for movement along an arcuate path with a fixed center of rotation. The seat is adjustable such that the center of gravity of the occupant is adapted to be substantially coincident with the center of rotation.
Another embodiment of the invention is directed to a personal mobility vehicle comprising a base, a plurality of wheels that are adapted to support the base relative to a supporting surface, a seat, one or more tracks having a constant radius arc supporting the seat for movement relative to the base, and a low friction support assembly supported by either the base or the seat or any combination thereof. The support permits an overall tilt angle range of the one or more tracks to be adjusted.
Another embodiment of the invention is directed to a personal mobility vehicle comprising a base, a plurality of wheels that are adapted to support the base relative to a supporting surface, a seat for supporting an occupant, and one or more tracks supporting the seat. The tracks serve as a rolling or sliding surface that allows the seat to rotate with respect to the base. The tracks have a constant or substantially constant radius arc with a focal point that is substantially fixed in space, whereby the location of the center of gravity of the occupant can be adjusted to be coincident or near coincident with the focal point.
Another embodiment of the invention is directed to a method for minimizing effort required to tilt the seat of a personal mobility vehicle. The method comprises the steps of providing a personal mobility vehicle having a seat that is adapted to move along an arc having a center of curvature, positioning the seat substantially horizontally, providing an occupant in the seat, and adjusting the position of the vehicle occupant's center of gravity so that the center of gravity is substantially equal to or below the center of curvature of the arc.
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.
Referring now to the drawings, there is illustrated in
The seat frame 20 is preferably adapted to support armrests 32 and footrest assemblies 34. The armrests 32 are preferably releasably attached to the seat frame 20 and movable in a longitudinal direction relative to the seat frame 20. The armrests 32 are preferably held in fixed relation to the seat frame 20 in any conventional manner, such as by the tube clamps 36 shown. The footrest assemblies 34 are also releasably and movably attached to the seat frame 20.
As illustrated in
The seat frame 20 is similarly comprised of opposing side frame members, such as the tubes 44 shown, and curved or substantially curved members, such as the tracks or rockers 46 shown, or a curved rack (not shown), joined by a plurality of longitudinally spaced, laterally extending members such as the tubes 48 shown. It should be noted that the laterally extending tubes 48 are preferably in the form of telescopic tubes that are adjustable relative to one another to permit the vehicle 10 to grow in width. The seat frame 20 is supported relative to the side tubes 40 by the rockers 46 via one or more support assemblies 50.
As shown in plain view, the side tubes 40 can support caster housings 52, which in turn are suitable for supporting the caster stems. The rear wheels 18 can be supported in a fixed relation to the side tubes 40 by any conventional means, including the axle mounting plate 54 shown.
The footrest assemblies 34 can include a member, such as the tube 56, that is telescopically received by, or otherwise adjustably related to, the side tubes 44. The tube 56 is preferably adjustable relative to the side tubes 44 to permit the longitudinal position of the tube 56 to be located in various fixed positions relative to the side tubes 44. This accommodates growth in the vehicle 10 in a longitudinal direction.
It should be noted that an alternative seat back 58 is shown in
As depicted in
Continuing with
In
The couplings 74 are preferably structured to be adjustable with minimal disassembly. As shown in
As clearly illustrated, the holes 102, 103 in the elongate saddles 84 are adapted to align with holes 111 in the side tubes 44 of the seat frame 20. The fasteners 106, 108 can be received in any of the aligned holes, for example, to accommodate growth in the vehicle 10 in a longitudinal direction and permit a wide range or variation in the positions of the footrest assemblies 34 and the support assemblies 50 to permit the vehicle occupant to be positioned with his or her center of gravity CG substantially coincident with the arc A of the focal point P.
In
The functionality of coupling 74 results from the use of elongate saddles 84. These saddles 84 permit angular and longitudinal adjustment of the canes 62 and plates 80 with greater ease than conventional coupling systems that perform a similar function. For both angular and longitudinal adjustment, the upper fasteners 90, 94 remain intact with plates 80 and saddles 82.
Angular adjustment of the cane 62 and plates 80 relative to the seat tube 44 of the illustrated coupling 74 can be accomplished by removing the front lower fastener 106 and loosening the back lower fastener 108 to reduce the clamping pressure of the plates 80 on the saddles 84 and the side tubes 44. The canes 62 and plates 80 can then freely rotate coincidentally about the rear plate holes 105 and rear saddle holes 103.
Longitudinal adjustment of the canes 62 and plates 80 of the illustrated coupling 74 can be accomplished by removing only the front and back lower fasteners 106, 108. No other parts require removal or are free to loosen or drop out during this adjustment because the back lower holes 105 in the plates 80 are coincidentally engaged about the bosses 110 of the saddles 84 and the plates 80 maintain a pre-load against the saddles 84 and side tube 44 due to the installed clamping force of upper fasteners 90, 94 so that the plates 80 remain engaged with the saddles 84. When the desired longitudinal location of the canes 62 along side tube 44 is established, the front and back lower fasteners 106,108 can be re-installed and secured in place.
It should be noted, that during longitudinal adjustments, pre-established angular settings of the canes 62 and plates 80 can be preserved by first removing the back rear fastener 108 from the holes 103, 105 in the saddles 84 and plates 80 and then placing the back rear fastener 108 completely through the holes 114 in the saddle tabs 114 and the scalloped holes 104 in the plates 80. The back rear fastener 108 is now in a shear mode that maintains the angular position of the cane 62 and the plates 80. Next, by removing front lower fastener 106, the entire assembly (i.e., the cane 62 and the plates 80) is free to translate longitudinally along side tube 44.
In
In
An alternative lock assembly 142 is illustrated in
In
In
As shown in
In
As illustrated in
It should be noted that the vehicle 10 can be comprised of two primary parts: the base 12 and the seat assembly 14. The seat assembly 14 can include the seat frame 20, the seat back 22, 58, and the footrest assembly 34, all preferably rigidly or substantially rigidly supported on the rockers 46. The support assemblies 50 can capture the rockers 46 and constrain the motion of the seat frame 20 to pure rotation about the rocker's center of curvature (i.e., focal point P).
In a preferred embodiment, four bottom rollers 162 (i.e., two rollers 162 per rocker 46) preferably support the underside surface of the rockers 46. These rollers 162 are preferably saddle-shaped to position the rockers 46 along the center of the support assembly 50. The rockers 46 preferably have a similarly shaped profile that fits within the saddle-shaped rollers 162. These mating shapes serve to align the rockers 46 with the rollers 162.
Four top rollers 170 (i.e., two top rollers 170 per rocker 46) preferably contact an upper curved surface of the rockers 46, capturing the rockers 46 and preventing the rockers 46 from lifting off the base 12. The top and bottom rollers 162, 170 allow the seat frame 20 to rotate with minimal friction about the center of curvature P of the rockers 46.
It should further be noted that the holes 136, which serve as the engagement features for the spring-loaded plunger pins 132, can be equally spaced and arranged in a series, for example, between the upper and lower surfaces of the rockers 46, along an arc concentric or substantially concentric with the curvature of the rockers 46. The holes 136 can be spaced discrete angular distances apart, such as one-degree apart, to permit incremental adjustments in the tilt angle of the seat frame 20. Multiple pins 132 could engage multiple holes 136 of the rockers 46 to reduce sheer forces encountered by the pins 132 when locking the rocker 46 in position. It should be clearly understood that the tilt angle of the seat frame 20 can be changed, for example, by squeezing levers to release the pins 132 from the holes 136 and rotating the seat frame 20 by pushing or pulling on handles. When the levers are released, the pins 132 can engage with the closest aligned holes 136, locking the seat frame 20 with respect to the base 12 at a specific tilt angle.
In order for the vehicle 10 to function as intended, a vehicle occupant's center of gravity should coincide closely with the center of curvature of the rockers. To this end, the vehicle occupant should be properly positioned at the center of curvature or substantially close to the center of curvature of the rockers. For example, the center of gravity of the vehicle occupant can be above the center of curvature or focal point of the rocker (i.e., when the seat frame is substantially horizontal, as shown in
The preferred embodiment of the invention can be summarized as a personal mobility vehicle having a seat or seating system that is supported for movement relative to a radial curve or a quasi radial curve (e.g., via a radially curved track or member, or a substantially radially curved track or member) having a focal point that is preferably substantially fixed in space, wherein the seat or seating system is adjustable (e.g., horizontally, vertically, or both) with respect to the curve so that the center of gravity of the seat is adjusted or the center of gravity of any vehicle occupant is sufficiently coincident with the focal point of the curve so that excessive force, or a significant amount of force, is not required to tilt the seat frame with the occupant therein. In one embodiment of the invention, the center of gravity can be sufficiently vertically aligned with the focal point when the seat or seating system is horizontal.
The relative position of the center of gravity of the vehicle occupant and the center of curvature or focal point obviously depends on the weight of the user, and possibly the physical abilities of the attendant. For example, a near coincident relationship between the center of gravity of the vehicle occupant and the focal point P that requires 50 pounds of force to tilt the seat frame and occupant may be a suitable relationship for some attendants but not others. Generally, the center of gravity is preferably within a one-inch radius about the focal point. Depending on the weight of the occupant, the center of gravity can be within a two and one-half inch radius about the focal point, though this may not be suitable of occupants exceeding certain weight capacities. The center of gravity can even be within a three to four inch radius about the focal point, although this may not be a possible range for very heavy occupants. With these ranges in mind, it is conceivable that center of gravity can even be within a radius about the focal point that is in a preferred range of about four to seven percent of the fore to aft length of the vehicle seat 24, or a possible suitable range of about 11 to 17 percent of the fore to aft length of the vehicle seat 24.
To establish a desired relationship between the center of gravity of the vehicle occupant and the focal point P of the arc A, the wheelchair 10 can incorporate several means for adjusting the position of the vehicle occupant to align the occupant's center of gravity CG with or close to the center of curvature of the rockers 46. The seat back 22, 58, the seat 24 (e.g., a pan, a sling, etc.), and the footrest assemblies 34 all preferably incorporate fore/aft adjustability with respect to the center of curvature. Couplings that secure the canes 26, 62 and seat 24 to the seat frame 20 preferably allow for fore/aft adjustability. The tubes 56 supporting the footrest assemblies 34 also preferably have fore/aft adjustability. This adjustability allows proper center of gravity CG alignment for a range of vehicle occupant sizes and accommodates occupant growth.
The center of curvature of the rockers 46 is a virtual point in space that can preferably reside close to the occupant's abdomen. Because the pivot point in this design is a virtual point in space, and not a physical pivot axis near the abdomen, the vehicle occupant is not confined by hardware or the vehicle structure that surrounds the occupant. The absence of any vehicle structure at this location is advantageous because the seating area remains unconfined. This assists in transferring the occupant in and out of the vehicle.
Proper positioning of the center of gravity CG of a vehicle occupant with respect to the base 12 is important for stability and maneuverability of the vehicle. Stability is ensured when the center of gravity CG is properly positioned between the front casters 16 and rear wheels 18 attached to the base frame 12. Increased maneuverability is achieved when the rear wheels 18 support a larger portion of an occupant's weight. Reducing the weight on the front casters 16 produces easier steering and facilitates lifting the front end of the vehicle when crossing thresholds. Because the vehicle 10 is intended to cover a wide range of occupant sizes, the vehicle footprint (i.e., the distance between the front casters 16 and the rear wheels 18) can grow.
The vehicle 10 incorporates several unique features to maintain stability and maneuverability while accommodating a wide range of occupant sizes. The seat frame 20 can be adjusted fore/aft with respect to the base 12. The seat frame 20 can be positioned with respect to the base 12 by moving the support assembly 50 fore/aft along the base 12. The rear wheels 18 may be positioned fore/aft along the base 12 as well. This ability to adjust the size of the vehicle footprint and position the occupant's center of gravity CG fore/aft within this footprint allows the vehicle to be properly configured for stability and maneuverability over a wide range of occupant sizes.
The support assembly 50 can be mounted on the base 12 in a plurality of different angular positions. These positions allow the range of tilt to be changed to accommodate a particular vehicle occupant's needs. Changing the first position allows the seat assembly 14 to tilt in a range of about 5° anterior to about 50° posterior. Changing the second position allows the seat assembly 14 to tilt in a range of about 0° to about 55° posterior. Changing the third position allows the seat assembly 14 to tilt in a range of about 5° posterior to about 60° posterior. An increased posterior tilt range provides more pressure relief to the ischial tuberosities. An increased anterior tilt range assists in transferring the vehicle occupant in and out of the vehicle 10 and allows a occupant to foot propel. These tilt ranges allow the tilt range to be customized to a particular occupant's needs.
The rocker 144 according to an alternative embodiment of the invention can be in the form of a round steel tubing, as partially shown in cross-section in
The invention described herein can be easily adapted to a battery-powered motor or actuator that could drive the tilt angle of the seating system. This adaptation could allow the tilt function of the vehicle to be operated by a control device that is accessible to either the attendant or the vehicle occupant. Likewise, the center of gravity seating system described herein could be mounted on a power base so that the wheels of the vehicle can be motor-driven.
The present invention is not intended to be limited to the embodiments shown and described above. The base and seat assembly illustrated and described above are merely provided for illustrative purposes. Other bases and seat frames can be suitable for carrying out the invention. The rockers are also provided for illustrative purposes. It should be understood that one or more tracks, other than the rockers shown and described, having radius curves with a center of curvature that is coincident or substantially coincident with the vehicle occupant's center of gravity may be suitable for carrying out the invention. The tracks can be supported by one of more rollers, slides, or other suitable low-friction members that allow the seat frame to rotate with respect to the base. Seat frame adjustments, including adjustments to the seat, the seat back, and the footrest assemblies, can be carried out in ways other than those set forth above. It should further be understood that the vehicle may or may not accommodate growth and further that growth accommodation may be carried out in a manner other than that described. It should also be appreciated that the seat frame and support assembly can be adjustable in a manner other than that described.
The present invention can achieve a truly stationary center of gravity during tilting. Minimal effort may be required on the part of the attendant or the vehicle occupant when tilting the seat assembly. No lifting or lowering of the occupant's center of gravity may be required to tilt the seat assembly. Because the tilting is preferably limited to pure rotation, the only effort required may be then regulated to overcome friction within the system.
The vehicle occupant should not experience a sensation of being pitched off balance during tilting. The sensation experienced during the center of gravity tilting should be more reassuring to the occupant and less likely to induce inadvertent reactions that could potentially injure the vehicle occupant.
The instant invention may also be advantageous in that the vehicle occupant's center of gravity may remain substantially stationary with respect to the base, thus increasing vehicle stability and allowing for a shorter base length. Having a shorter base frame increases the maneuverability of the vehicle and creates a smaller overall footprint for the vehicle, allowing it to fit within tighter confines.
Lastly, the present invention permits the weight distribution on the front and rear wheels of the vehicle to remain constant while tilting the seat frame 20. The well-defined weight distribution assists in controlling and steering of the vehicle.
The principle and mode of operation of this invention have been explained and illustrated in its preferred embodiment. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.
This application is a continuation-in-part of U.S. patent application Ser. No. 10/403,998, filed Mar. 31, 2003, which is incorporated herein by reference.
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Number | Date | Country | |
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20050116440 A1 | Jun 2005 | US |
Number | Date | Country | |
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Parent | 10403998 | Mar 2003 | US |
Child | 10913005 | US |