US20060087166A1 - Power lift and tilt modules - Google Patents
Power lift and tilt modules Download PDFInfo
- Publication number
- US20060087166A1 US20060087166A1 US11/250,007 US25000705A US2006087166A1 US 20060087166 A1 US20060087166 A1 US 20060087166A1 US 25000705 A US25000705 A US 25000705A US 2006087166 A1 US2006087166 A1 US 2006087166A1
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- Prior art keywords
- members
- tilt
- motion
- actuator
- seat
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- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B66—HOISTING; LIFTING; HAULING
- B66F—HOISTING, LIFTING, HAULING OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD
- B66F7/00—Lifting frames, e.g. for lifting vehicles; Platform lifts
- B66F7/06—Lifting frames, e.g. for lifting vehicles; Platform lifts with platforms supported by levers for vertical movement
- B66F7/065—Scissor linkages, i.e. X-configuration
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61G—TRANSPORT, PERSONAL CONVEYANCES, OR ACCOMMODATION SPECIALLY ADAPTED FOR PATIENTS OR DISABLED PERSONS; OPERATING TABLES OR CHAIRS; CHAIRS FOR DENTISTRY; FUNERAL DEVICES
- A61G5/00—Chairs or personal conveyances specially adapted for patients or disabled persons, e.g. wheelchairs
- A61G5/04—Chairs or personal conveyances specially adapted for patients or disabled persons, e.g. wheelchairs motor-driven
- A61G5/041—Chairs or personal conveyances specially adapted for patients or disabled persons, e.g. wheelchairs motor-driven having a specific drive-type
- A61G5/043—Mid wheel drive
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61G—TRANSPORT, PERSONAL CONVEYANCES, OR ACCOMMODATION SPECIALLY ADAPTED FOR PATIENTS OR DISABLED PERSONS; OPERATING TABLES OR CHAIRS; CHAIRS FOR DENTISTRY; FUNERAL DEVICES
- A61G5/00—Chairs or personal conveyances specially adapted for patients or disabled persons, e.g. wheelchairs
- A61G5/10—Parts, details or accessories
- A61G5/1056—Arrangements for adjusting the seat
- A61G5/1059—Arrangements for adjusting the seat adjusting the height of the seat
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61G—TRANSPORT, PERSONAL CONVEYANCES, OR ACCOMMODATION SPECIALLY ADAPTED FOR PATIENTS OR DISABLED PERSONS; OPERATING TABLES OR CHAIRS; CHAIRS FOR DENTISTRY; FUNERAL DEVICES
- A61G5/00—Chairs or personal conveyances specially adapted for patients or disabled persons, e.g. wheelchairs
- A61G5/10—Parts, details or accessories
- A61G5/1056—Arrangements for adjusting the seat
- A61G5/1075—Arrangements for adjusting the seat tilting the whole seat backwards
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61G—TRANSPORT, PERSONAL CONVEYANCES, OR ACCOMMODATION SPECIALLY ADAPTED FOR PATIENTS OR DISABLED PERSONS; OPERATING TABLES OR CHAIRS; CHAIRS FOR DENTISTRY; FUNERAL DEVICES
- A61G5/00—Chairs or personal conveyances specially adapted for patients or disabled persons, e.g. wheelchairs
- A61G5/10—Parts, details or accessories
- A61G5/1089—Anti-tip devices
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B66—HOISTING; LIFTING; HAULING
- B66F—HOISTING, LIFTING, HAULING OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD
- B66F7/00—Lifting frames, e.g. for lifting vehicles; Platform lifts
- B66F7/06—Lifting frames, e.g. for lifting vehicles; Platform lifts with platforms supported by levers for vertical movement
- B66F7/0608—Lifting frames, e.g. for lifting vehicles; Platform lifts with platforms supported by levers for vertical movement driven by screw or spindle
Definitions
- This invention relates in general to personal mobility vehicles and more particularly, to seating systems for personal mobility vehicles. Most particularly, this invention relates to the mechanisms for lifting and/or tilting seat assemblies for wheelchairs and like vehicles.
- Mechanisms for lifting and/or tilting wheelchair seat assemblies are well known. Such mechanisms typically include an actuator (i.e., a lead screw, nut, motor, and gearbox). By convention, parts of the actuator are integrated in the base and parts of the actuator are integrated in the seat assembly. Such actuators encounter a high load from an initial or lowered position. This high load typically causes premature wear of the actuator. A lifting and/or tilting mechanism is needed that is in the form of a compact unit that is capable of lifting heavy loads.
- an actuator i.e., a lead screw, nut, motor, and gearbox
- the present invention is directed towards a modular actuator that meets the foregoing needs.
- the modular actuator has a cam member in combination with a scissors mechanism in a compact unit that is capable of lifting heavy loads.
- the invention is directed towards an actuator having component parts that may be integrated with the base or the seat assembly in such a manner that the parts are not integrated with both the base and the seat assembly.
- the invention is also directed towards a pull member that is capable of controlling and combining two different mechanisms that travel at different rates through two ranges of motion.
- the invention is still further directed towards a lifting and/or tilting assembly that includes two different actuator mechanisms that function to apply lifting and/or tilting force throughout different periods of operation, whereby transition from one mechanism to the other mechanism is substantially undetected by one supported by the assembly.
- the invention is further directed towards a cam member having a profile that is dimensioned and configured to maintain a constant range of motion and keep a constant load on the actuator.
- FIG. 1 is a rear perspective view of a wheelchair and a modular actuator according to the present invention.
- FIGS. 2A and 2B are enlarged front perspective views of lift modules according to alternative embodiments of the present invention.
- FIG. 3 is an enlarged front perspective view of a nut assembly of the lift modules shown in FIG. 2B .
- FIGS. 4A and 4B are cross-sectional views in elevation of the lift modules shown in FIGS. 2A and 2B in lowered positions.
- FIGS. 5A and 5B are cross-sectional views in elevation of the lift modules shown in FIGS. 2A and 2B in partially raised positions.
- FIGS. 6A and 6B are cross-sectional views in elevation of the lift modules shown in FIGS. 2A and 2B in fully raised positions.
- FIG. 7 is an enlarged partial front perspective view of the lift module shown in FIG. 2B in a lowered position.
- FIG. 8 is a graph of the load profile of the lift modules.
- FIG. 9 is a front perspective view of a tilt module according to one embodiment of the present invention.
- FIG. 10 is a rear perspective view of a tilt module according to another embodiment of the present invention.
- FIG. 11 a rear perspective view of the tilt module shown in FIG. 10 with portions removed to permit viewing of a secondary over-tilt lock and a one-way clutch and further showing enlarged detail views of the secondary over-tilt lock and the one-way clutch.
- FIG. 12 a front perspective view of the tilt module shown in FIG. 10 with portions removed to permit viewing of an over-tilt lock and a position sensor and further showing enlarged detail views of the over-tilt lock and the position sensor.
- FIG. 13 is front perspective view of the lift and tilt modules stacked upon one another.
- the wheelchair 10 is a power wheelchair and more particularly, a mid-wheel drive wheelchair, although the invention can be practiced with other suitable drive configurations, such as front and rear wheel drive configurations.
- the wheelchair 10 comprises a base 12 , which includes a frame supported on a supporting surface by a plurality of wheels, such as drive wheels 14 , front wheels 16 , and rear wheels 18 , as shown in the drawing.
- the drive wheels 14 can be powered by any suitable power source and can be controlled by any suitable input device, including but not limited to a joystick (not shown).
- a seat assembly 20 is supported by the base 12 .
- the seat assembly 20 comprises a seat 22 and a seat back 24 , which may articulate (i.e., recline) relative to the seat 22 .
- the seat assembly 20 is adapted to be supported by one or more modular actuators 26 , 76 that may be controlled to tilt and/or lift the seat assembly 20 .
- the lift modules 26 comprise a first member 28 , which is adapted to be secured to the base 12 , and the second member 30 , to which the seat assembly 20 is adapted to be secured, and which is adapted to move relative to the first member 28 .
- the first member 28 comprises a bottom plate 32 and a plurality of side walls, including longitudinal side walls 34 a , 34 b and end walls 36 a , 36 b .
- the second member 30 comprises a top plate 38 and a plurality of side walls, including longitudinal side walls 40 a , 40 b and end walls 42 .
- the first and second members 28 and 30 are configured to form housings for enclosing or otherwise supporting other elements of the lift module 26 . It should be appreciated that the particular configuration of the lift module 26 shown is provided for illustrative purposes and that the invention may be practiced with other configurations.
- the first and second members 28 and 30 are connected together by a lift mechanism, such as the scissors mechanism 44 shown.
- the scissors mechanism 44 comprise members 46 , 48 that cross and are pivotally connected to one another.
- forward ends of the cross members 46 , 48 are pivotally connected proximate to forward regions of the longitudinal side walls 34 a , 34 b , 40 a , 40 b of the first and second members 28 and 30 .
- Rearward ends of the cross members 46 , 48 are slidably and pivotally connected proximate to rear regions of the longitudinal side walls 34 a , 34 b , 40 a , 40 b of the first and second members 28 and 30 .
- the latter connection may be provided by opposing tracks 50 a , 50 b , 52 a , 52 b (shown in FIG. 2B ) proximate the rear regions of the longitudinal side walls 34 a , 34 b , 40 a , 40 b of the first and second members 28 and 30 .
- the scissors mechanism 44 is preferably driven by a lead screw 54 , which in turn can be driven by a motor 56 , or other suitable prime mover.
- the motor 56 may indirectly drive the lead screw 54 through a gearbox 58 , as shown in the drawings.
- the lead screw 54 may carry for longitudinal movement a nut assembly 60 , as shown more clearly in FIG. 3 .
- the nut assembly 60 includes an internal thread 62 for engagement with the lead screw 54 .
- the nut assembly 60 has a nut 60 a therein. Webbing 60 b in a semi-cylindrical portion 60 c of the nut assembly 60 aids in trapping the nut 60 a within the nut assembly 60 .
- the illustrated nut assembly is provided for illustrative purposes and that the invention may be practiced or carried out with other assemblies or configurations.
- the nut assembly 60 has means for supporting pull members.
- the supporting means may take on any form, the particular means shown includes support members and more particularly, laterally extending support members 64 .
- the particular support members 64 shown may be shaped to provide clearance for other elements of the lift module 26 , including but not limited to, for example, the motor 56 .
- the support members 64 may also be structured to withstand longitudinal forces.
- the support members 64 cooperate with pull members, such as the pull members 66 shown in FIGS. 2A and 2B .
- the pull members 66 as shown in the drawings, may include but are not limited to pull rods, although other pull members may be suitable for practicing the invention.
- a portion of the nut assembly 60 , a medial portion 68 in the illustrated embodiment shown in FIG. 3 may support one or more low friction elements.
- One or more low friction elements such as the surface rollers 70 shown, may be provided for engagement with and movement relative to the first member 28 of the lift module 26 .
- One or more other low friction elements such as the cam rollers 72 a , 72 b shown, may be provided for engagement with and movement relative to a cam member 74 a , 74 b , which will be described in greater detail below.
- One or more cam members 74 a , 74 b are adapted to engage the low friction elements 72 a , 72 b . As shown in FIGS. 4A and 4B , when the lift module 26 is in a lowered or initial position, the cam rollers 72 a , 72 b engage the cam members 74 a , 74 b . As the lead screw 54 is driven by the motor 56 (shown in FIGS. 2A and 2B ) and gearbox 58 , the lead screw 54 threads the nut assembly (i.e., from left to right when viewing the drawings).
- the cam rollers 72 a , 72 b push up on the cam members 74 a , 74 b , and the cross member 46 of the scissors mechanism 44 pushes up on the second member 30 of the lift module 26 .
- the cam rollers 72 a , 72 b and cam members 74 a , 74 b are beneficial to raise the second member 30 when the scissors mechanism 44 has insufficient mechanical advantage.
- the cam members 74 a , 74 b have slots or grooves 74 c that receive nubs or pins 60 d on opposing sides of the nut assembly 60 , as shown in FIG. 3 .
- the grooves 74 c and pins 60 d function as guides and stops for the cam members 74 a , 74 b .
- pins 60 d and grooves 74 c function to prevent an external force from inadvertently lifting or tilting the scissors mechanism 44 prior to the nut assembly 60 transferring the load from the cam rollers 72 a , 72 b to the pull members 66 , as will be described in greater detail in the description that follows.
- the scissors mechanism 44 is pulled by the pull members 66 (shown in FIGS. 2A and 2B ) via the nut assembly 60 .
- the pull members 66 pull the scissors mechanism 44 , the pull members 66 are not in tension.
- the cross members 46 act to lift the second member 30 of the lift module 26 by virtue of the connection between the cam members 74 a , 74 b and the cross members 46 .
- the nut assembly 60 continues to pull the pull members 66 , which are placed in tension, and which in turn pull the cross members 46 of the scissors mechanism 44 .
- the scissors mechanism 44 has a sufficient mechanical advantage to lift the second member 30 of the lift module 26 .
- the transition between the cam members 74 a , 74 b and the scissors mechanism 44 should be smooth because the cam rollers 72 a , 72 b reach the end of the profile of the cam members 74 a , 74 b when the mechanical advantage of the scissors mechanism 44 is sufficient to raise the second member 30 under load to a fully raised position, as shown in FIGS. 6A and 6B .
- the pull members 66 contribute to combine two ranges of motion (i.e., via the cam members 74 a , 74 b and the scissors mechanism 44 ) and two rates (i.e., different rates) of motion into one continuous motion. This is graphically illustrated in FIG. 8 , which simulates load versus time of the lift module 26 .
- the vertical axis represents motor current draw or motor load and the horizontal axis represents travel of the nut assembly 60 .
- the relative flat curve is provided to maximize the performance of the motor 56 and gearbox 58 and reduce or eliminate any perceived transfer of function from cam members 74 a , 74 b to pull members 66 .
- the graph in FIG. 8 represent an ideal operational characteristic of the invention, actual data may not support a line that is as flat, as represented.
- FIGS. 9 and 10 Another modular actuator according to the present invention is illustrated in FIGS. 9 and 10 .
- This modular actuator is in the form of a tilt module 76 .
- the tilt module 76 is similar to the lift module 26 described above in that the tilt module 76 comprises a first member 28 , which is adapted to be secured to a wheelchair base, and the second member 30 , to which a wheelchair seat is adapted to be secured, and which moves relative to the first member 28 .
- the first member 28 comprises a bottom plate 32 and a plurality of side walls, including longitudinal side walls 34 a , 34 b and end walls 36 a , 36 b .
- the second member 30 comprises a top plate 38 and a plurality of side walls, including longitudinal side walls 40 a , 40 b and an end wall 42 .
- the first and second members 28 and 30 are configured to form housings for enclosing or otherwise supporting other elements of the tilt module 76 . It should be appreciated that the particular configuration of the tilt module 76 shown is provided for illustrative purposes and that the invention may be practiced with other configurations.
- the first and second members 28 and 30 are connected together by a modified scissors mechanism, such as the scissors mechanism 78 shown.
- the scissors mechanism 78 comprises one or more tilt members 80 and struts 82 that are pivotally connected to the tilt members 80 .
- lower ends of the tilt members 80 are slidably and pivotally connected proximate to rearward regions of the longitudinal side walls 34 a , 34 b of the first member 28 .
- Lower ends of the struts 82 are pivotally connected proximate to forward regions of the longitudinal side walls 34 a , 34 b of the first members 28 .
- the former connection may be provided by opposing tracks 84 a , 84 b (shown in FIG.
- the tilt module 76 is preferably driven by a lead screw 54 (shown in FIG. 9 ), which in turn can be driven by a motor 56 (shown in FIG. 9 ), or other suitable prime mover.
- the motor 56 may indirectly drive the lead screw 54 through a gearbox 58 (shown in FIG. 9 ).
- the lead screw 54 may carry for longitudinal movement a nut assembly 60 , like that shown in FIG. 3 .
- the nut assembly 60 includes an internal thread 62 for engagement with the lead screw 54 . It should be noted that the nut assembly 60 has a nut 60 a therein.
- Webbing 60 b in a semi-cylindrical portion 60 c of the nut assembly 60 aids in trapping the nut 60 a within the nut assembly 60 . It should be appreciated that the illustrated nut assembly is provided for illustrative purposes and that the invention may be practiced or carried out with other assemblies or configurations.
- the nut assembly 60 has means for supporting pull members.
- the supporting means may take on any form, the particular means shown includes support members and more particularly, laterally extending support members 64 .
- the particular support members 64 shown may be shaped to provide clearance for other elements of the tilt module 76 , including but not limited to, for example, the motor 56 .
- the support members 64 may also be structured to withstand longitudinal forces.
- the support members 64 cooperate with pull members 66 , such as, for example, the pull rods shown in FIG. 10 , although other pull members may be suitable for practicing the invention.
- One or more low friction elements such as the surface rollers 70 shown, may be provided for engagement with and movement relative to the second member 30 of the tilt module 76 .
- One or more other low friction elements such as the cam rollers 72 a , 72 b shown, may be provided for engagement with and movement relative to a cam member 74 a , 74 b.
- One or more cam members 74 a , 74 b are adapted to engage the low friction elements 72 a , 72 b .
- the cam rollers 72 a , 72 b engage the cam members 74 a , 74 b .
- the lead screw 54 threads the nut assembly 60 .
- the cam rollers 72 a , 72 b push up on the cam members 74 a , 74 b , which push up on the second member 30 of the tilt module 76 .
- the cam rollers 72 a , 72 b and cam members 74 a , 74 b are beneficial to push up the second member 28 when the tilt mechanism 44 has insufficient mechanical advantage.
- a transition is made from the cam members 74 a , 74 b to the tilt members 80 and struts 82 when the cam rollers 72 a , 72 b reach the end of the profile of the cam members 74 a , 74 b .
- the tilt members 80 are pulled by the pull members 66 via the nut assembly 60 .
- This transition should be smooth because the cam rollers 72 a , 72 b reach the end of the profile of the cam members 74 a , 74 b when the mechanical advantage of the tilt members 80 and struts 82 is sufficient to raise the first member 28 under load to a fully raised position, as shown in the drawings.
- the pull members 66 contribute to combine two ranges of motion (i.e., via the cam members 74 a , 74 b and the tilt members 80 and struts 82 ) and two rates of travel into one continuous motion.
- an over-tilt lock as shown in FIGS. 9 and 10 , may be provided.
- the over-tilt lock locks out the pull members 66 between a minimum and a maximum tilt angle (e.g., between about 0 degrees and about 50 degrees) just prior to when the user's weight shifts and goes from a positive force in a clockwise direction (when viewing FIG. 9 ) to a positive force in a counter clockwise direction (when viewing FIG. 9 ) about the tilt pivot point. This prevents the seat assembly 20 from inadvertently over tilting.
- the affects of shifts in the user's weight are dependent on, for example, the user's weight, the center of gravity of the seat assembly 20 and the user combined, and the relationship between the center of gravity and the tilt axis.
- Positioning of the module 76 and/or the motor 56 and/or the gearbox 58 could effectively position the center of gravity over the module 76 and the wheelchair base 12 as desired.
- a spring 106 may be provided to function as an over-tilt mechanism to be used in conjunction with or in lieu of the over-tilt lock.
- a load reversal may occur as the tilt module 76 tilts back beyond a certain threshold, that is, when the user's weight shifts and goes from a positive force in one direction to a positive force in another clockwise direction about the tilt pivot point, or to a negative force.
- the spring 106 may be provided for positively biasing the load in as this shift occurs to a negative force.
- the spring functions a load compensating mechanism may be employed to balance the load applied against the motor 56 during operation of the modules 26 , 76 .
- one or more helical coil springs 106 cooperate with the scissors mechanisms 44 , 78 .
- a spring 106 may be carried by a rigid rod, which is within the spring 106 , and which may be present on opposing sides of the modules 26 , 76 . The rod may be free to move in a longitudinal direction through operation of the modules 26 , 76 and prevent the spring 106 from moving radially.
- a first end of the rod is connected to a movable block 108 while a second end of the rod, opposite the first end, is a free end (i.e., not physical fixed).
- the spring 106 may be at least partially encased in a sleeve 110 , tube, or the like, which further prevents the spring 106 from moving radially. In this way, the spring 106 is maintained along a substantially linear axis coincident with the longitudinal axes of the rod and the sleeve 110 .
- the mechanical advantage may not be constant. As a consequence, the load on the motor 56 may be greater during certain periods of operation.
- the motor 56 may operate at a greater speed. This may be undesirable. That is to say, it may be desirable to operate the motor 56 at a substantially constant rate of motion.
- the spring 106 may be compressed by the scissors mechanisms 44 , 78 during operation of the modules 26 , 76 . As a consequence, the load applied by the spring 106 increases as the scissors mechanisms 44 , 78 gain a greater mechanical advantage.
- the spring 106 Since the spring 106 is compressed throughout the operation of the modules 26 , 76 , the spring 106 could offer little to no resistance initially when the modules 26 , 76 , and more particularly, the scissors mechanisms 44 , 78 are first operated (i.e., when the load on the motor 56 is greatest), and offer greater resistance as the load on the motor 56 decreases due to the mechanical advantage of the scissors mechanisms 44 , 78 . In this way, the motor 56 may be operated at a substantially constant rate of motion.
- the over-tilt lock function of the tilt module 76 is embodied in two separate mechanisms.
- the over tilt function may be carried out by the pins 60 d on the nut assembly 60 engaging the grooves 74 c on the cam members 74 a , 74 b , as shown in FIG. 11 .
- the cam rollers 72 a , 72 b disengage from the cam members 74 a , 74 b , a secondary over tilt lock is engaged.
- the lower set of pull members 66 each have a single timing pin 98 and a single locking pin (not shown) extending in a radial direction from the long axis of the pull member 66 .
- the timing pin 98 engages an “S” shaped timing slot 102 in the base 32 of the tilt module 76 .
- the locking pin is housed in a matching slot 104 in the lateral support members 64 of the nut assembly 60 (shown in FIG. 3 ). As the cam members 74 a , 74 b transition the length of the bottom plate 32 , the nut assembly 60 pulls all the pull members 66 .
- the lower set of pull rods 66 with the timing pin 98 is fully extended between the nut assembly 60 and the pivot connections at the rearward ends of the scissors mechanism 78 .
- the lower pull rod timing pin 98 is moved through the timing slot 102 in the base 32 while this pull rod 66 is pulled into a tensile load condition. While this transition to a tensile load condition is accomplished, the locking pin in the lower pull rod 66 comes out of the mating slot in the lateral support members 64 of the nut assembly 60 and, through the rotation of the pull rod 66 via the timing pin 98 , is now prevented from retreating back into the mating slot 104 . With this pull rod 66 now prevented from retreating back into the support arm member 64 in over tilt condition, this pull rod 66 becomes a compression member instead of a tensile member, holding the parts stationary and preventing inadvertent over tilt.
- the present invention may further comprise a position sensor 90 , as shown in FIG. 12 .
- the sensor 90 may be in the form of an optical encoder or reader that counts the number of turns or revolutions of the lead screw 54 to determine the position of the actuator. This sensor may be used in conjunction with or in lieu of position switches, such as end switches and the inhibit switches 96 c described below, to reduce available tilt angle, adjust the angle at which reduced speed of the wheelchair base will be implemented, or act as a fine tuning adjustment for what is considered a bottom angle or “home” position for the tilt.
- the present invention may further comprise a one-way anti-back drive clutch 92 , as shown in FIG. 12 , that prevents the weight of the user from closing the actuator.
- the motor 56 may be free to turn unencumbered by frictional resistance in one direction to raise the user.
- resistance prevents the actuator from creeping down due to the load imposed on the actuator by the weight of the user. This is particularly useful when lead screw 54 is not a self locking thread design and the nut assembly 60 is as low friction as possible to allow a smaller motor per weight. Under conditions where the motor 56 is neither being driven up or down, the weight of the user can be enough to cause the lead screw 54 to be back driven in a downward command direction.
- the one-way clutch 92 may freewheel when the motor 56 rotates in a direction to increase the tilt angle of the tilt module 76 , or to increase the lift height of the lift module 26 .
- the one way clutch engages and impedes the tendency of the motor 56 to reduce the tilt angle.
- the motor 56 can overpower the clutch on demand, but the weight of the user is not sufficient to reduce tilt angle, or the lift height.
- This function can also be accomplished by a conventional electrical brake (not shown) on the motor armature shaft.
- the clutch is preferred over that of an electrical brake as release of an electrical brake can allow over rapid decrease in tilt angle, or lift height.
- the present invention may also have a switch rail 94 , as shown in FIG. 12 , or may otherwise support one or more position switches.
- the switch rail 94 shown may support two end switches (not shown) and an inhibit switch 96 c between the end switches.
- the end switches are threshold switches that prevent further operation of the actuator when the actuator reaches upper and lower operating limits.
- the end switches may be normally open switched.
- a support member 64 may engage an end switch to close the end switch at that end of the switch rail 94 .
- the closed switch may produce a signal representing that the nut assembly 60 has been driven a threshold distance in a first direction.
- a controller could recognize this as a threshold condition and, for example, prevent the motor 56 from further operating and thus prevent the tilt module 76 from tilting further back. However, the motor 56 remains operable to turn in an opposite direction to return the module 76 forward toward a non-tilted orientation until, for example, the support member 64 of the nut assembly 60 closes the other end switch at the other end of the switch rail 94 .
- the end switches need not be normally open switches. The type of end switch used depending on the design of the electronics. Regardless of the switch orientation, the switches may operate as described above.
- the inhibit switch 96 c may prevent operation of the wheelchair 10 , or limit performance of the wheelchair 10 under a certain condition.
- the inhibit switch 96 c may signal the wheelchair base 10 when a certain height of lift, or a certain degree of tilt has been attained. Above a certain amount of lift or degree of tilt, the top operating speed of the wheelchair can or will be reduced to reduce or eliminate the occurrence of accidents resulting from a compromised driving position or compromised stability standpoint.
- the inhibit switch 96 c may be a mid-travel rocker switch, which may, for example, be a single pole switch, double throw switch that is thrown in a first direction to decrease the motor speed beyond a certain tilt angle, either when raising or lowering the top plate 38 , and that is thrown in a second direction to permit the motor 56 to operate at an increased motor speed below that tilt angle.
- the mid-travel rocker switch may function to reduce the available drive motor speed above a certain angle of tilt, via activation by the nut assembly 60 , and restore full drive motor speed below that angle as the nut assembly 60 directs the switch throw back to a full motor speed setting.
- the modular actuators i.e., the lift and tilt modules 26 , 76
- the actuators are compact units that have high load carrying abilities.
- the actuators are adapted for use in new wheelchairs, or for use in converting existing wheelchairs, to wheelchairs having lift and tilt capabilities.
- the actuators could integrate with existing wheelchairs in a relatively short time with minimal efforts.
- the likeness of the lift and tilt modules 26 , 76 would minimize component parts. That is to say, but for the scissors mechanisms 44 , 78 , the component part of the lift and tilt modules 26 , 76 may be substantially identical. Since the lift and tilt modules 26 , 76 use common components to achieve two distinctly different modes of operations (i.e., lifting and tilting operations), economy in inventory and production is achieved.
- the lift and tilt modules 26 , 76 may be removable, reversible, and adjustable.
- the lift and tilt modules 26 , 76 may function as structural elements of the wheelchair, and have low profiles that are particularly useful for wheelchair seat lifting and center of gravity seat tilting. This also allows lift and tilt wheelchairs to be offered with a low seat to floor height. High load bearing characteristics are achieved through the entire cycle of operation by two working mechanisms.
- the cam members 74 a , 74 b function to push the second member 30 upward.
- the scissors mechanism 44 , or the tilt members 80 and struts 82 takes over when enough mechanical advantage is available.
- cam members 74 a , 74 b lifts loads in a low profile.
- These two mechanisms i.e., cam members 74 a , 74 b and scissors mechanism 44 , or the tilt members 80 and struts 82
- the pull members 66 marry the cam members 74 a , 74 b and the scissors mechanism 80 , 82 as well as the scissors mechanism 44 so that the difference in the rate of motion of the two components (i.e., cam members 74 a , 74 b and the scissors mechanism 44 ) is not noticeable.
- the lift and tilt modules 26 and 76 are adapted to be stacked upon one another. This permits the wheelchair seat assembly 20 to be lifted, tilted, or lifted and tilted, as shown.
- each module i.e., lift and tilt module
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Abstract
A modular actuator has a combination cam member and scissors mechanism in a compact unit that is capable of lifting heavy loads. A pull member is capable of controlling and combining two different mechanisms that travel at different rates through two ranges of motion. The cam member has a profile that is dimensioned and configured to maintain a constant range of motion.
Description
- This application claims the benefit of U.S. Provisional Patent Application No. 60/621,439, filed on Oct. 22, 2004.
- This invention relates in general to personal mobility vehicles and more particularly, to seating systems for personal mobility vehicles. Most particularly, this invention relates to the mechanisms for lifting and/or tilting seat assemblies for wheelchairs and like vehicles.
- Mechanisms for lifting and/or tilting wheelchair seat assemblies are well known. Such mechanisms typically include an actuator (i.e., a lead screw, nut, motor, and gearbox). By convention, parts of the actuator are integrated in the base and parts of the actuator are integrated in the seat assembly. Such actuators encounter a high load from an initial or lowered position. This high load typically causes premature wear of the actuator. A lifting and/or tilting mechanism is needed that is in the form of a compact unit that is capable of lifting heavy loads.
- The present invention is directed towards a modular actuator that meets the foregoing needs. According to one embodiment of the invention, the modular actuator has a cam member in combination with a scissors mechanism in a compact unit that is capable of lifting heavy loads. Moreover, the invention is directed towards an actuator having component parts that may be integrated with the base or the seat assembly in such a manner that the parts are not integrated with both the base and the seat assembly. The invention is also directed towards a pull member that is capable of controlling and combining two different mechanisms that travel at different rates through two ranges of motion. The invention is still further directed towards a lifting and/or tilting assembly that includes two different actuator mechanisms that function to apply lifting and/or tilting force throughout different periods of operation, whereby transition from one mechanism to the other mechanism is substantially undetected by one supported by the assembly. The invention is further directed towards a cam member having a profile that is dimensioned and configured to maintain a constant range of motion and keep a constant load on the actuator.
- 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.
-
FIG. 1 is a rear perspective view of a wheelchair and a modular actuator according to the present invention. -
FIGS. 2A and 2B are enlarged front perspective views of lift modules according to alternative embodiments of the present invention. -
FIG. 3 is an enlarged front perspective view of a nut assembly of the lift modules shown inFIG. 2B . -
FIGS. 4A and 4B are cross-sectional views in elevation of the lift modules shown inFIGS. 2A and 2B in lowered positions. -
FIGS. 5A and 5B are cross-sectional views in elevation of the lift modules shown inFIGS. 2A and 2B in partially raised positions. -
FIGS. 6A and 6B are cross-sectional views in elevation of the lift modules shown inFIGS. 2A and 2B in fully raised positions. -
FIG. 7 is an enlarged partial front perspective view of the lift module shown inFIG. 2B in a lowered position. -
FIG. 8 is a graph of the load profile of the lift modules. -
FIG. 9 is a front perspective view of a tilt module according to one embodiment of the present invention. -
FIG. 10 is a rear perspective view of a tilt module according to another embodiment of the present invention. -
FIG. 11 a rear perspective view of the tilt module shown inFIG. 10 with portions removed to permit viewing of a secondary over-tilt lock and a one-way clutch and further showing enlarged detail views of the secondary over-tilt lock and the one-way clutch. -
FIG. 12 a front perspective view of the tilt module shown inFIG. 10 with portions removed to permit viewing of an over-tilt lock and a position sensor and further showing enlarged detail views of the over-tilt lock and the position sensor. -
FIG. 13 is front perspective view of the lift and tilt modules stacked upon one another. - Referring now to the drawings, there is illustrated in
FIG. 1 a wheelchair 10 and a modular actuator according to the present invention. Thewheelchair 10 is a power wheelchair and more particularly, a mid-wheel drive wheelchair, although the invention can be practiced with other suitable drive configurations, such as front and rear wheel drive configurations. Thewheelchair 10 comprises abase 12, which includes a frame supported on a supporting surface by a plurality of wheels, such asdrive wheels 14,front wheels 16, andrear wheels 18, as shown in the drawing. Thedrive wheels 14 can be powered by any suitable power source and can be controlled by any suitable input device, including but not limited to a joystick (not shown). Aseat assembly 20 is supported by thebase 12. Theseat assembly 20 comprises aseat 22 and a seat back 24, which may articulate (i.e., recline) relative to theseat 22. According to the present invention, theseat assembly 20 is adapted to be supported by one or moremodular actuators seat assembly 20. - Modular actuators in the form of
lift modules 26 are shown inFIGS. 2A and 2B . Thelift modules 26 comprise afirst member 28, which is adapted to be secured to thebase 12, and thesecond member 30, to which theseat assembly 20 is adapted to be secured, and which is adapted to move relative to thefirst member 28. In the illustrated embodiment of the invention, thefirst member 28 comprises abottom plate 32 and a plurality of side walls, includinglongitudinal side walls end walls second member 30 comprises atop plate 38 and a plurality of side walls, includinglongitudinal side walls end walls 42. The first andsecond members lift module 26. It should be appreciated that the particular configuration of thelift module 26 shown is provided for illustrative purposes and that the invention may be practiced with other configurations. - The first and
second members scissors mechanism 44 shown. Thescissors mechanism 44 comprisemembers cross members longitudinal side walls second members cross members longitudinal side walls second members opposing tracks FIG. 2B ) proximate the rear regions of thelongitudinal side walls second members - The
scissors mechanism 44 is preferably driven by alead screw 54, which in turn can be driven by amotor 56, or other suitable prime mover. Themotor 56 may indirectly drive thelead screw 54 through agearbox 58, as shown in the drawings. Thelead screw 54 may carry for longitudinal movement anut assembly 60, as shown more clearly inFIG. 3 . In the illustrated embodiment of the invention, thenut assembly 60 includes aninternal thread 62 for engagement with thelead screw 54. It should be noted that thenut assembly 60 has anut 60 a therein.Webbing 60 b in asemi-cylindrical portion 60 c of thenut assembly 60 aids in trapping thenut 60 a within thenut assembly 60. It should be appreciated that the illustrated nut assembly is provided for illustrative purposes and that the invention may be practiced or carried out with other assemblies or configurations. - As shown in
FIG. 3 , thenut assembly 60 has means for supporting pull members. Although the supporting means may take on any form, the particular means shown includes support members and more particularly, laterally extendingsupport members 64. Theparticular support members 64 shown may be shaped to provide clearance for other elements of thelift module 26, including but not limited to, for example, themotor 56. Thesupport members 64 may also be structured to withstand longitudinal forces. Thesupport members 64 cooperate with pull members, such as thepull members 66 shown inFIGS. 2A and 2B . Thepull members 66, as shown in the drawings, may include but are not limited to pull rods, although other pull members may be suitable for practicing the invention. - A portion of the
nut assembly 60, amedial portion 68 in the illustrated embodiment shown inFIG. 3 , may support one or more low friction elements. One or more low friction elements, such as thesurface rollers 70 shown, may be provided for engagement with and movement relative to thefirst member 28 of thelift module 26. One or more other low friction elements, such as thecam rollers cam member - One or
more cam members low friction elements FIGS. 4A and 4B , when thelift module 26 is in a lowered or initial position, thecam rollers cam members lead screw 54 is driven by the motor 56 (shown inFIGS. 2A and 2B ) andgearbox 58, thelead screw 54 threads the nut assembly (i.e., from left to right when viewing the drawings). Thecam rollers cam members cross member 46 of thescissors mechanism 44 pushes up on thesecond member 30 of thelift module 26. Thecam rollers cam members second member 30 when thescissors mechanism 44 has insufficient mechanical advantage. It should be noted that thecam members grooves 74 c that receive nubs or pins 60 d on opposing sides of thenut assembly 60, as shown inFIG. 3 . Thegrooves 74 c and pins 60 d function as guides and stops for thecam members pins 60 d andgrooves 74 c function to prevent an external force from inadvertently lifting or tilting thescissors mechanism 44 prior to thenut assembly 60 transferring the load from thecam rollers pull members 66, as will be described in greater detail in the description that follows. - A transition is made from the
cam members scissors mechanism 44 when thecam rollers cam members FIGS. 5A and 5B . It should be noted that throughout the operation of thecam members scissors mechanism 44, particularly thecross members 46, is pulled by the pull members 66 (shown inFIGS. 2A and 2B ) via thenut assembly 60. Although thepull members 66 pull thescissors mechanism 44, thepull members 66 are not in tension. Thecross members 46 act to lift thesecond member 30 of thelift module 26 by virtue of the connection between thecam members cross members 46. At the transition between thecam members scissors mechanism 44, thenut assembly 60 continues to pull thepull members 66, which are placed in tension, and which in turn pull thecross members 46 of thescissors mechanism 44. At this transition point, thescissors mechanism 44 has a sufficient mechanical advantage to lift thesecond member 30 of thelift module 26. The transition between thecam members scissors mechanism 44 should be smooth because thecam rollers cam members scissors mechanism 44 is sufficient to raise thesecond member 30 under load to a fully raised position, as shown inFIGS. 6A and 6B . Thepull members 66 contribute to combine two ranges of motion (i.e., via thecam members FIG. 8 , which simulates load versus time of thelift module 26. In the graph, the vertical axis represents motor current draw or motor load and the horizontal axis represents travel of thenut assembly 60. The relative flat curve is provided to maximize the performance of themotor 56 andgearbox 58 and reduce or eliminate any perceived transfer of function fromcam members members 66. Although the graph inFIG. 8 represent an ideal operational characteristic of the invention, actual data may not support a line that is as flat, as represented. - Another modular actuator according to the present invention is illustrated in
FIGS. 9 and 10 . This modular actuator is in the form of atilt module 76. Thetilt module 76 is similar to thelift module 26 described above in that thetilt module 76 comprises afirst member 28, which is adapted to be secured to a wheelchair base, and thesecond member 30, to which a wheelchair seat is adapted to be secured, and which moves relative to thefirst member 28. In the illustrated embodiment of the invention, thefirst member 28 comprises abottom plate 32 and a plurality of side walls, includinglongitudinal side walls walls second member 30 comprises atop plate 38 and a plurality of side walls, includinglongitudinal side walls end wall 42. The first andsecond members tilt module 76. It should be appreciated that the particular configuration of thetilt module 76 shown is provided for illustrative purposes and that the invention may be practiced with other configurations. - The first and
second members scissors mechanism 78 shown. Thescissors mechanism 78 comprises one ormore tilt members 80 and struts 82 that are pivotally connected to thetilt members 80. In the illustrated embodiment of the invention, lower ends of thetilt members 80 are slidably and pivotally connected proximate to rearward regions of thelongitudinal side walls first member 28. Lower ends of thestruts 82 are pivotally connected proximate to forward regions of thelongitudinal side walls first members 28. The former connection may be provided by opposingtracks FIG. 9 ) proximate the rear regions of thelongitudinal side walls first members 28. The latter connection may be provided by opposingpivot bosses 86 b (only one shown inFIG. 9 ) proximate the forward regions of thelongitudinal side walls first members 28. - The
tilt module 76, like thelift module 26 described above, is preferably driven by a lead screw 54 (shown inFIG. 9 ), which in turn can be driven by a motor 56 (shown inFIG. 9 ), or other suitable prime mover. Themotor 56 may indirectly drive thelead screw 54 through a gearbox 58 (shown inFIG. 9 ). Thelead screw 54 may carry for longitudinal movement anut assembly 60, like that shown inFIG. 3 . In the preferred embodiment of the invention, thenut assembly 60 includes aninternal thread 62 for engagement with thelead screw 54. It should be noted that thenut assembly 60 has anut 60 a therein.Webbing 60 b in asemi-cylindrical portion 60 c of thenut assembly 60 aids in trapping thenut 60 a within thenut assembly 60. It should be appreciated that the illustrated nut assembly is provided for illustrative purposes and that the invention may be practiced or carried out with other assemblies or configurations. - As described above with reference to the
lift module 26, thenut assembly 60 has means for supporting pull members. Although the supporting means may take on any form, the particular means shown includes support members and more particularly, laterally extendingsupport members 64. Theparticular support members 64 shown may be shaped to provide clearance for other elements of thetilt module 76, including but not limited to, for example, themotor 56. Thesupport members 64 may also be structured to withstand longitudinal forces. Thesupport members 64 cooperate withpull members 66, such as, for example, the pull rods shown inFIG. 10 , although other pull members may be suitable for practicing the invention. - A portion of the
nut assembly 60, amedial portion 68 in the illustrated embodiment, supports one or more low friction elements. One or more low friction elements, such as thesurface rollers 70 shown, may be provided for engagement with and movement relative to thesecond member 30 of thetilt module 76. One or more other low friction elements, such as thecam rollers cam member - One or
more cam members low friction elements tilt module 76 is in a lowered or initial position, thecam rollers cam members lead screw 54 is driven by themotor 56 andgearbox 58, thelead screw 54 threads thenut assembly 60. Thecam rollers cam members second member 30 of thetilt module 76. Thecam rollers cam members second member 28 when thetilt mechanism 44 has insufficient mechanical advantage. - A transition is made from the
cam members tilt members 80 and struts 82 when thecam rollers cam members tilt members 80 are pulled by thepull members 66 via thenut assembly 60. This transition should be smooth because thecam rollers cam members tilt members 80 and struts 82 is sufficient to raise thefirst member 28 under load to a fully raised position, as shown in the drawings. Thepull members 66 contribute to combine two ranges of motion (i.e., via thecam members tilt members 80 and struts 82) and two rates of travel into one continuous motion. - According to a preferred embodiment of the invention, an over-tilt lock, as shown in
FIGS. 9 and 10 , may be provided. The over-tilt lock locks out thepull members 66 between a minimum and a maximum tilt angle (e.g., between about 0 degrees and about 50 degrees) just prior to when the user's weight shifts and goes from a positive force in a clockwise direction (when viewingFIG. 9 ) to a positive force in a counter clockwise direction (when viewingFIG. 9 ) about the tilt pivot point. This prevents theseat assembly 20 from inadvertently over tilting. Obviously, the affects of shifts in the user's weight are dependent on, for example, the user's weight, the center of gravity of theseat assembly 20 and the user combined, and the relationship between the center of gravity and the tilt axis. Positioning of themodule 76 and/or themotor 56 and/or thegearbox 58 could effectively position the center of gravity over themodule 76 and thewheelchair base 12 as desired. - It should be noted that a
spring 106 may be provided to function as an over-tilt mechanism to be used in conjunction with or in lieu of the over-tilt lock. As stated above, a load reversal may occur as thetilt module 76 tilts back beyond a certain threshold, that is, when the user's weight shifts and goes from a positive force in one direction to a positive force in another clockwise direction about the tilt pivot point, or to a negative force. Thespring 106 may be provided for positively biasing the load in as this shift occurs to a negative force. - In addition, the spring functions a load compensating mechanism may be employed to balance the load applied against the
motor 56 during operation of themodules scissors mechanisms spring 106 may be carried by a rigid rod, which is within thespring 106, and which may be present on opposing sides of themodules modules spring 106 from moving radially. In the illustrated embodiment of the invention, a first end of the rod is connected to amovable block 108 while a second end of the rod, opposite the first end, is a free end (i.e., not physical fixed). It should be noted that thespring 106 may be at least partially encased in asleeve 110, tube, or the like, which further prevents thespring 106 from moving radially. In this way, thespring 106 is maintained along a substantially linear axis coincident with the longitudinal axes of the rod and thesleeve 110. Throughout the operation of thescissors mechanisms motor 56 may be greater during certain periods of operation. During periods when the load on themotor 56 is reduced, themotor 56 may operate at a greater speed. This may be undesirable. That is to say, it may be desirable to operate themotor 56 at a substantially constant rate of motion. In accordance with the invention, thespring 106 may be compressed by thescissors mechanisms modules spring 106 increases as thescissors mechanisms spring 106 is compressed throughout the operation of themodules spring 106 could offer little to no resistance initially when themodules scissors mechanisms motor 56 is greatest), and offer greater resistance as the load on themotor 56 decreases due to the mechanical advantage of thescissors mechanisms motor 56 may be operated at a substantially constant rate of motion. - The over-tilt lock function of the
tilt module 76 is embodied in two separate mechanisms. When thenut assembly 60 is in contact with thecam members pins 60 d on thenut assembly 60 engaging thegrooves 74 c on thecam members FIG. 11 . When thecam rollers cam members FIG. 11 , there are twopull members 66 per side of thetilting module 76. The lower set ofpull members 66 each have asingle timing pin 98 and a single locking pin (not shown) extending in a radial direction from the long axis of thepull member 66. Thetiming pin 98 engages an “S” shaped timing slot 102 in thebase 32 of thetilt module 76. The locking pin is housed in amatching slot 104 in thelateral support members 64 of the nut assembly 60 (shown inFIG. 3 ). As thecam members bottom plate 32, thenut assembly 60 pulls all thepull members 66. The lower set ofpull rods 66 with thetiming pin 98 is fully extended between thenut assembly 60 and the pivot connections at the rearward ends of thescissors mechanism 78. The lower pullrod timing pin 98 is moved through the timing slot 102 in thebase 32 while thispull rod 66 is pulled into a tensile load condition. While this transition to a tensile load condition is accomplished, the locking pin in thelower pull rod 66 comes out of the mating slot in thelateral support members 64 of thenut assembly 60 and, through the rotation of thepull rod 66 via thetiming pin 98, is now prevented from retreating back into themating slot 104. With thispull rod 66 now prevented from retreating back into thesupport arm member 64 in over tilt condition, thispull rod 66 becomes a compression member instead of a tensile member, holding the parts stationary and preventing inadvertent over tilt. - The present invention may further comprise a
position sensor 90, as shown inFIG. 12 . Thesensor 90, for example, may be in the form of an optical encoder or reader that counts the number of turns or revolutions of thelead screw 54 to determine the position of the actuator. This sensor may be used in conjunction with or in lieu of position switches, such as end switches and the inhibit switches 96 c described below, to reduce available tilt angle, adjust the angle at which reduced speed of the wheelchair base will be implemented, or act as a fine tuning adjustment for what is considered a bottom angle or “home” position for the tilt. - The present invention may further comprise a one-way anti-back drive clutch 92, as shown in
FIG. 12 , that prevents the weight of the user from closing the actuator. For example, themotor 56 may be free to turn unencumbered by frictional resistance in one direction to raise the user. However, resistance prevents the actuator from creeping down due to the load imposed on the actuator by the weight of the user. This is particularly useful whenlead screw 54 is not a self locking thread design and thenut assembly 60 is as low friction as possible to allow a smaller motor per weight. Under conditions where themotor 56 is neither being driven up or down, the weight of the user can be enough to cause thelead screw 54 to be back driven in a downward command direction. The one-way clutch 92 may freewheel when themotor 56 rotates in a direction to increase the tilt angle of thetilt module 76, or to increase the lift height of thelift module 26. When electrical power to themotor 56 is removed or themotor 56 is driven in a direction to reduce the tilt angle, or the lift height, the one way clutch engages and impedes the tendency of themotor 56 to reduce the tilt angle. Themotor 56 can overpower the clutch on demand, but the weight of the user is not sufficient to reduce tilt angle, or the lift height. This function can also be accomplished by a conventional electrical brake (not shown) on the motor armature shaft. The clutch is preferred over that of an electrical brake as release of an electrical brake can allow over rapid decrease in tilt angle, or lift height. - The present invention may also have a
switch rail 94, as shown inFIG. 12 , or may otherwise support one or more position switches. For example, theswitch rail 94 shown may support two end switches (not shown) and an inhibitswitch 96 c between the end switches. The end switches are threshold switches that prevent further operation of the actuator when the actuator reaches upper and lower operating limits. For example, the end switches may be normally open switched. When thenut assembly 60 reaches one end of theswitch rail 94, asupport member 64 may engage an end switch to close the end switch at that end of theswitch rail 94. The closed switch may produce a signal representing that thenut assembly 60 has been driven a threshold distance in a first direction. A controller could recognize this as a threshold condition and, for example, prevent themotor 56 from further operating and thus prevent thetilt module 76 from tilting further back. However, themotor 56 remains operable to turn in an opposite direction to return themodule 76 forward toward a non-tilted orientation until, for example, thesupport member 64 of thenut assembly 60 closes the other end switch at the other end of theswitch rail 94. It should be appreciated that the end switches need not be normally open switches. The type of end switch used depending on the design of the electronics. Regardless of the switch orientation, the switches may operate as described above. The inhibitswitch 96 c may prevent operation of thewheelchair 10, or limit performance of thewheelchair 10 under a certain condition. The inhibitswitch 96 c may signal thewheelchair base 10 when a certain height of lift, or a certain degree of tilt has been attained. Above a certain amount of lift or degree of tilt, the top operating speed of the wheelchair can or will be reduced to reduce or eliminate the occurrence of accidents resulting from a compromised driving position or compromised stability standpoint. For example, the inhibitswitch 96 c may be a mid-travel rocker switch, which may, for example, be a single pole switch, double throw switch that is thrown in a first direction to decrease the motor speed beyond a certain tilt angle, either when raising or lowering thetop plate 38, and that is thrown in a second direction to permit themotor 56 to operate at an increased motor speed below that tilt angle. That is to say the mid-travel rocker switch may function to reduce the available drive motor speed above a certain angle of tilt, via activation by thenut assembly 60, and restore full drive motor speed below that angle as thenut assembly 60 directs the switch throw back to a full motor speed setting. - The modular actuators (i.e., the lift and
tilt modules 26, 76) according to the present invention are compact units that have high load carrying abilities. The actuators are adapted for use in new wheelchairs, or for use in converting existing wheelchairs, to wheelchairs having lift and tilt capabilities. The actuators could integrate with existing wheelchairs in a relatively short time with minimal efforts. The likeness of the lift andtilt modules scissors mechanisms tilt modules tilt modules tilt modules tilt modules scissors mechanism 44, or thetilt members 80 and struts 82, thecam members second member 30 upward. Thescissors mechanism 44, or thetilt members 80 and struts 82, takes over when enough mechanical advantage is available. Thecam members cam members scissors mechanism 44, or thetilt members 80 and struts 82) may be tuned (i.e., dimensioned and configured) to keep the load on themotor 56 andgearbox 58 constant to maximize the life of the drive train (i.e., themotor 56 and gearbox 58). - It should also be appreciated that the
pull members 66 marry thecam members scissors mechanism scissors mechanism 44 so that the difference in the rate of motion of the two components (i.e.,cam members - As shown in
FIG. 13 , the lift andtilt modules wheelchair seat assembly 20 to be lifted, tilted, or lifted and tilted, as shown. - In a preferred embodiment of the invention, each module (i.e., lift and tilt module) is relatively thin and is most preferably about two inches in height to insure that the minimum seat height is maintained.
- 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.
Claims (8)
1. A modular actuator for moving a seat of a personal mobility vehicle through two ranges of motion comprising a first mechanism that operates to move the seat through a first one of the ranges of motion and a second mechanism that operates to move the seat through a second one of the ranges of motion.
2. The actuator according to claim 1 wherein the actuator is a lift module and the first mechanism is one or more cam members that are adapted to cooperate with one or more cam rollers and the second mechanism is a scissors mechanism.
3. The actuator according to claim 2 wherein the one or more cam members are dimensioned and configured to maintain a constant load throughout the first range of motion and a load consistent with the second range of motion.
4. The actuator according to claim 1 wherein the actuator is a tilt module and the first mechanism is one or more cam members that are adapted to cooperate with one or cam rollers and the second mechanism is one or more tilt members that are adapted to cooperate with one or more struts.
5. The actuator according to claim 4 wherein the cam member is dimensioned and configured to maintain a constant load throughout the first range of motion and a load consistent with the second range of motion.
6. A modular actuator for moving a seat of a personal mobility vehicle through two ranges of motion comprising a first mechanism therein that operates to move the seat through a first one of the ranges of motion and a second mechanism that that operates to move the seat through a second one of the ranges of motion, the first and second mechanisms being within a compact unit.
7. The actuator according to claim 6 wherein the first and second mechanisms and other component parts thereof are integrated in such a manner so as not to be integrated with both the seat or a base of the personal mobility vehicle.
8. The actuator according to claim 6 wherein the actuator is self contained and readily attachable to existing personal mobility vehicles.
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
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US11/250,007 US20060087166A1 (en) | 2004-10-22 | 2005-10-13 | Power lift and tilt modules |
PCT/US2005/038049 WO2006047342A2 (en) | 2004-10-22 | 2005-10-20 | Power lift and tilt modules |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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US62143904P | 2004-10-22 | 2004-10-22 | |
US11/250,007 US20060087166A1 (en) | 2004-10-22 | 2005-10-13 | Power lift and tilt modules |
Publications (1)
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US20060087166A1 true US20060087166A1 (en) | 2006-04-27 |
Family
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Application Number | Title | Priority Date | Filing Date |
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US11/250,007 Abandoned US20060087166A1 (en) | 2004-10-22 | 2005-10-13 | Power lift and tilt modules |
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US (1) | US20060087166A1 (en) |
WO (1) | WO2006047342A2 (en) |
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Also Published As
Publication number | Publication date |
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WO2006047342A3 (en) | 2007-02-22 |
WO2006047342A2 (en) | 2006-05-04 |
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Owner name: SUNRISE MEDICAL HHG INC., COLORADO Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:TRIPPENSEE, DARIN;STEVENS, REX;VAUGHT, JESSE;AND OTHERS;REEL/FRAME:017103/0006 Effective date: 20051011 |
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STCB | Information on status: application discontinuation |
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