Abstract:
A multi-directional lever drive system comprising a lever drive assembly comprising a lever for imparting actuation for driving a shaft through a roller mechanism, and engaging a switch assembly whereby the properties of the roller mechanism can be selected to drive the shaft forward, neutral, and reverse. The proposed switch assemblies enable convenient direction control from the same lever that inputs actuation to the drive assembly, making the lever drive assembly suitable for systems such as a lever propelled wheelchair, a winch, and hand tools.

Description:
RELATED APPLICATIONS 
     This application claims priority and is entitled to the filing date of U.S. Provisional application Ser. No. 61/752,763, filed on Jan. 15, 2013, and entitled “Multi-directional Lever Drive System.” The contents of the aforementioned application are incorporated by reference herein. 
    
    
     INCORPORATION BY REFERENCE 
     Applicant(s) hereby incorporate herein by reference any and all patents and published patent applications cited or referred to in this application. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     Aspects of this invention relate generally to drive mechanisms and systems, and more particularly to multi-directional lever drive systems. 
     2. Description of Related Art 
     The following art defines the present state of this field: 
     U.S. Pat. No. 6,715,780 to Schaeffer is directed to a manual wheelchair system comprising of a pair of lever arms positioned on each side of the chair that actuate a propulsion system located entirely under the seat of the wheelchair. Both the push and pull stroke of the levers, unlimited by stroke angle, provide unidirectional forward propulsion to the rear wheels of the chair. This is accomplished through drive gears fitted with one-way clutches and idler gears intermeshing with them. A sprocket is attached to one drive gear, and connects to an internal shifting hub using a chain or belt. This hub could optionally be a manual or automatic unit, with the automatic shifting unit retying on sensory feedback from the rear drive wheel to determine the most efficient ratio of operation. The hub connects to the rear drive axle through another sprocket and chain combination and drives the rear wheel as the levers are manipulated. The rear axle has a disconnecting clutch so that the entire drive propulsion system can be disengaged from the chair. This allows the operator to use the wheelchair in a conventional manner (by hand directly at the wheel handrails). 
     U.S. Pat. Nos. 6,893,035 and 7,261,309 to Watwood are directed to a wheelchair which shifts between forward and reverse by virtue of a roller mechanism which grabs in one direction and slips in the opposite direction, thereby preventing binding. The shift mechanism is initiated by rotation of a shift paddle which is located on an extremity of a lever arm remote from the roller mechanism. 
     U.S. Pat. Nos. 7,963,539 and 8,540,266 to Baker are directed to a wheelchair comprising a main frame and a seat mounted on the main frame. A pair of front wheels and a pair of rear wheels are also mounted on the frame. A propulsion mechanism is provided for driving the rear wheels, the propulsion mechanism comprising an arm lever for forward and back movement and a gear train between the arm lever and the rear wheels. 
     U.S. Pat. No. 8,186,699 to Green is directed to a manual propulsion mechanism for wheelchairs that utilizes a lever pivotally mounted to the hub of each rear wheel such that the wheelchair user can propel the chair with push/pull movements of the levers. Forward and reverse propulsion directions are accomplished by a system of one-way reversible clutches contained in the propulsion wheel hubs which also allow the levers to be operationally disconnected such that the chair can freewheel. Operator control of direction shifting is through pivoting motions imparted to the grip handles of the propulsion levers. In a preferred embodiment, improved ergonomics thr propulsion direction changes are made possible by coordinating the direction of the shift pivot motion with the push/pull movement of the levers. This allows the operator to retain a comfortable, stable grip on the grip handle while simultaneously propelling and controlling direction of movement. 
     U.S. Patent Application Publication No. 20130015632 to Amos Winter is directed to a manually powered wheelchair including a first lever associated with a first rear wheel and demountably coupled to a first drivetrain, the first lever having a first brake thereon. The wheelchair also includes a second lever associated with a second rear wheel and demountably coupled to a second drivetrain, the second lever having a second brake thereon. Each drivetrain includes a chainring, a chain, and a freewheel, and each drivetrain has a fixed gear ratio. The freewheel of each drivetrain is actuated by manual pivoting of the lever associated therewith. In use, the wheelchair achieves changes in mechanical advantage when a user shifts the user&#39;s hands up and down the first and second levers. 
     European Patent Application Publication No. EP2586570 to Weiyi Wang is directed to a bidirectional mechanical converting unit, comprising: a main shaft, a driving mechanism, which includes a driving means and a reversing means which are coupled to each other, and a rotation means for inputting torque, a rotation axis of the rotation means being coaxial with the main shaft, the rotation means and the driving mechanism being coupled to each other, and the driving mechanism delivering the torque to output at the main shaft at a predetermined direction, no matter in which direction the rotation means rotates, wherein the predetermined direction can be switched via the reversing means. 
     The prior art described above teaches various wheelchairs and wheelchair drive mechanisms and a two-way mechanical converter, but does not teach a lever mechanism that drives a unidirectional output from both push and pull stroke of the lever, and enables the user to change the output drive direction from the distal end of the lever, where the input torque is applied. Aspects of the present invention fulfill these needs and provide further related advantages as described in the following summary. 
     SUMMARY OF THE INVENTION 
     Aspects of the present invention teach certain benefits in construction and use which give rise to the exemplary advantages described below. 
     The present invention solves the problems described above by providing a method for a multi-directional lever drive system that has a unidirectional output torque as a result of both input stroke directions, and enables the direction of the output torque to be set from the distal end of the lever where the user input is located. The apparatus provides, in the exemplary embodiment, a lever that is coupled to a mount for driving means and coupled to a switch assembly to change the output direction of said driving means. In one embodiment the user rotates the lever about the switch axis to change the drive setting between forward, neutral, and reverse; and the user pivots the lever about the drive axis to input torque to the lever system. In a second embodiment, an electromechanical switch assembly is employed. 
     A primary objective inherent in the above described apparatus and method of use is to provide advantages not taught by the prior art. 
     Another objective is to provide such an apparatus that has less complexity and moving components than other lever drive systems, enabling a relatively lightweight, compact system ideal for mobile devices, such as a manually propelled wheelchair, in at least one embodiment. 
     Other features and advantages of aspects of the present invention will become apparent from the following more detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of aspects of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings illustrate aspects of the present invention. In such drawings: 
         FIG. 1  is a side schematic view of an exemplary multi-directional lever drive system, in accordance with at least one embodiment; 
         FIG. 2  is a partial top exploded perspective schematic view of an exemplary multi-directional lever drive system as in  FIG. 1  employing an exemplary lever drive assembly thereof as in  FIG. 3 , in accordance with at least one embodiment; 
         FIG. 3  is an enlarged exploded perspective schematic view of a first exemplary lever drive assembly thereof, in accordance with at least one embodiment; 
         FIG. 4  is an enlarged perspective schematic view of a second exemplary lever drive assembly thereof, in accordance with at least one embodiment; 
         FIG. 5A  is an enlarged partial side schematic view of a shaft clutch assembly thereof, in accordance with at least one embodiment; 
         FIGS. 5B-D  are enlarged partial side schematic views of the shaft clutch assembly of  FIG. 5A  shown in three exemplary operational modes, in accordance with at least one embodiment; 
         FIG. 6A  is an enlarged front schematic view of an electromechanical lever drive assembly; and 
         FIG. 6B  is an enlarged cross-sectional view of a electromechanical switch assembly in one embodiment. 
     
    
    
     The above described drawing figures illustrate aspects of the invention in at least one of its exemplary embodiments, which are further defined in detail in the following description. Features, elements, and aspects of the invention that are referenced by the same numerals in different figures represent the same, equivalent, or similar features, elements, or aspects, in accordance with one or more embodiments. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The above described drawing figures illustrate aspects of the invention in at least one of its exemplary embodiments, which are further defined in detail in the following description. As a threshold matter, it is noted that each of the drawings are presented as schematics in order to convey aspects of the present invention but are not to be taken literally or to scale. 
     Regarding  FIG. 1 , an exemplary embodiment of the lever drive assembly  20  is applied to the context of an ergonomic manually-propelled wheelchair system or overall lever drive system  10  having two larger drive wheels  152  and two front castor wheels  150 , a seat  140 , a backrest  146 , and a footrest  154 . While a wheelchair context is thus the exemplary context of the lever drive assembly  20  according to aspects of the present invention, it will be appreciated that such context is merely illustrative and that the invention may be employed in a variety of other contexts without departing from its spirit and scope. As illustrated, said lever actuated bi-directional mechanical converter apparatus or lever drive assembly  20  may be mounted to the frame assembly  130  of the wheelchair and operably coupled to a rear drive assembly  120  through a transmission comprising in one configuration a rear sprocket  116 , a chain  126 , and a front sprocket  110 . Said lever apparatus  20  may include a hand grip  39  on the distal end  26  of the lever  22  for a user sitting in the chair to operate and propel the chair with a pull and push, and select a drive mode from the distal lever end  26  with one of the methods described below. Furthermore, said distal lever end  26  may comprise a brake lever  125  to operate a brake caliper  123 , which engages a brake disc  122 . Said lever  22  may comprise more than one section such that a proximal first portion  34  and distal second portion  36  are slidably coupled, such that the lever arm length can change to increase or decrease the mechanical advantage achieved by said lever apparatus  20 . 
     Turning to  FIG. 2 , a rear drive assembly  120  comprises, in an exemplary configuration, a spindle  128  comprising a mount for a rear sprocket (not shown), a mount for a disk brake (not shown), and a spline extrude  129  for coupling said spindle  128  to a removable drive wheel hub  114  with a matching spline bore. Said drive wheel hub  114  may be removably fixed by a wheelchair axle  112 . Said spindle  128  is mounted through a rear bracket  136  with bearings (not shown) fixed within a base bracket  132  of the frame assembly  130  such that the rear spindle  128  rotates according to input from said rear wheel  152  and said lever actuated bi-directional mechanical converter apparatus  20 . 
     Turning now to  FIG. 3 , there is shown an enlarged exploded perspective schematic view of a first exemplary lever drive assembly  20  thereof, in at least one embodiment according to aspects of the present invention. The lever drive assembly  20  comprises, in the exemplary embodiment, a lever  22  with a lever distal end  26  and a lever proximal end  24  coupled to a mount  68  through a mount hole  70 , such that said lever  22  may rotate about the axis of said mount hole  70 , referred to as a switch axis, which in this embodiment is the same as the lever axis  23 , and rotation of said lever  22  about said lever axis  23  engages a switch assembly  80  that maintains the settings of a shaft clutch assembly  40 , more about both of which is said below. 
     With continued referenced to  FIG. 3 , said mount  68  is operably coupled to a first drive element  74 , and said drive element  74  rotates about a drive axis  43 . In one preferred embodiment, a single drive element  74  enables the user to output torque through the lever  22  in one input direction and idle in the opposite direction. In a second preferred embodiment, said first drive element  74  is coupled to a second drive element  76  through one or more intermediate gears  78  positioned by a mount boss  72 , resulting in said second drive element  76  rotating oppositely to said first drive element  74 , enabling the user to output torque through the lever in both input directions. Said drive elements  74 ,  76  are positioned coaxially to a shaft  42  and selectively coupled to said shaft  42  by bi-directional roller clutches comprised of one or more roller bearings  64 , a commutation sleeve  54 , and one or more cam surfaces  50  on said shaft  42 , such that said drive elements  74 ,  76  have a circumferential surface  77  that aligns with said sleeve lengthwise slot  62  which positions the roller bearing  64  between said drive member circumferential surface  77  and a shaft cam surface  50 . Said commutation sleeve  54  comprises a distal end  60  that surrounds the shaft cam section  48  and comprises at least one and up to the number of cam surfaces  50  lengthwise slots  62  axially displaced such that each set of lengthwise slots  62  is surrounded by said circumferential surface  77  of said drive element  74 ,  76 . Said commutation sleeve  54  further comprises a proximal end  56  that is axially fixed and rotatably concentric with a shaft annular section  44 . Said proximal commutation sleeve end  56  comprises in the exemplary embodiment a helical groove  58  for coupling to said switch assembly  80 , though it will be appreciated by those skilled in the art that the helical groove  58  may instead be incorporated within the switch assembly  80  or on the shaft  42  or coupling member  100  and then coupled through a pinned connection or the like to the sleeve  54 . That is, there may be provided first and second means for imparting rotational movement of the sleeve  54  relative to the shaft  42 , such as a helical groove  58  and associated pin  86 , as discussed further below, and it will be appreciated that any such means and the incorporation of any such means, now known or later developed, within the invention are possible without departing from its spirit and scope. 
     Referring still to  FIG. 3 , in one exemplary embodiment said mount hole  70  is parallel to a lever axis  23  and said proximal lever end  24  comprises a lever gear  32  that engages a switch member  82  comprised of a switch gear surface  96  such that as the lever  22  rotates about the lever axis  23 , said lever gear  32  drives the switch member  82  along the drive axis  43 . Said switch member  82  comprises a contoured switch bore  84  that matches a non-cylindrical contour coupling member surface  100  fixed to the shaft  42  such that the shaft  42  and switch member  82  rotate substantially in tandem with each other, while the switch member  82  may move axially along the shaft  42  with zero or greater pitch, however the lever gear  32  is mated to the switch gear  96  thus enabling the operator to control the axial position of said switch member  82  by positioning said lever  22  to a desired angular position about the lever axis  23  for a particular drive setting. Said switch member  82  further comprises a switch pin  86  that projects substantially radially inwardly such that it fits inside the helical groove  58  on the proximal end  56  of said commutation sleeve  54 , resulting in said commutation sleeve  54 , said shaft  42 , and said switch member  82  rotating substantially in tandem; furthermore, as the switch member  82  moves axially, said switch pin  86  moves in said helical groove  58  of said commutation sleeve  54 , causing said commutation sleeve  54  to rotate with respect to said shaft  42 , changing the position of said lengthwise slots  62  and said rollers  64  on said shaft cam surface  50 , thus changing the drive properties of the shaft clutch assembly  40  and thus the lever drive assembly  20 . 
     Regarding  FIG. 4 , an alternative embodiment of the lever drive assembly  20  according to aspects of the present invention has a switch axis  71  and mount hole  70  perpendicular to both said lever axis  23  and said drive axis  43 . A lever gear  32  or pawl on the proximal end  24  of the lever  22  engages the switch member  82  such that pivoting of the lever  22  about said switch axis  71  transfers to axial movement of said switch member  82 . Said lever gear  32  or pawl engages a switch gear  96  or groove as a means to transmit forces axially along the shaft  42 , yet enables the switch member  82  to rotate independently from the lever  22  and vice versa. It is noted that the lever  22  is shown as being cut so as to convey an overall length greater than that shown, with such cut rendering the distal end  26  appearing to be offset from the proximal end  24 , but it should be appreciated that the full lever  22  may be along a single lever axis  23  and that, in any case, the ergonomic geometry and positioning of the distal end  26  of the lever is not critical to the operation of the overall lever drive assembly  20  or particularly of the “working” proximal end  24  of the lever  22 . The lever assembly  20  can be fixed to a frame or surface through the attachment holes  75  on the mount boss  72 . 
     One objective of the switch assembly  80  is to control rotation of the sleeve  54  relative to the shaft  42 . An alternative method to the helical groove  58  of the sleeve  54  is to have one or more straight grooves on the proximal end of the commutation sleeve  54 , and a helical contour on the shaft  42  that substantially pairs with a switch bore, such that as the switch is advanced axially along the shaft, it rotates about the shaft axis  43  with a pitch necessary to achieve the desired sleeve position. As before, the switch member  82  has a switch pin  86  that would project radially inwardly and align with the straight groove of the commutation sleeve  54  so as to rotate said sleeve  54  substantially in tandem with said shaft  42  and said switch member  82 . 
     Turning now to  FIG. 5A , there is shown a cross-sectional view of a bi-directional roller shaft clutch assembly  40  comprising one or more rollers  64 , a drive element  74  with circumferential surface  77 , a cam shaft  48  with one or more cam surfaces  50 , and a commutation sleeve  54  that fits circumferentially about said cam shaft  48 . Said commutation sleeve  54  comprises one or more lengthwise slots  62  ( FIG. 3 ) that are slightly larger than said roller bearing  64  such that said lengthwise slot  62  positions said roller bearing  64  on said cam surface  50 . Said commutation sleeve  54  has three distinct settings that determine the drive characteristics of the bi-directional clutch assembly  40 . When said commutation sleeve  54  positions said roller bearing  64  in simultaneous contact with said cam surface  50  and said drive element  74 , the roller bearing  64  will transmit torque from the drive element  74  to the shaft  48  in one direction ( FIGS. 5B and 5C ), yet idle when the drive element  74  is driven in the opposite direction. If the roller bearing  64  is positioned such that it is in contact with either said cam surface  50  or said drive element  74 , torque is not transferred from the drive element  74  to the shaft  48  by the roller ( FIG. 5D ). Once again, those skilled in the art will appreciate that other means for mechanically coupling the shaft  42  to the drive mechanism, here the commutation sleeve  54 , whether now know or later developed, may be employed in the present invention without departing from its spirit and scope. 
     Turning now to  FIG. 6A , there is shown another possible embodiment to achieve substantially the same functionality, having a lever drive assembly  20  that drives the drive element of the shaft clutch assembly  40  as before, and utilizing a switch assembly  80  comprising one or more electromechanical actuators  160  to drive and maintain the position of the commutation sleeve  54 . In such a configuration a user interface  178  may be located on said lever distal end  26  and provide means for the user to control the electromechanical actuator assembly  160 . As illustrated, said user interface  178  is a double-pole, double-throw rocker switch that enables an electrical potential from a battery  168  to be switched between two electrodes, in this embodiment, two brushes  166 . Said brushes  166  may be spring-biased to remain in contact with electrical bushings  164  coupled to said shaft  42 , such that the brushes  166  maintain electrical contact with the electrical bushings  164  as the shaft  42  rotates independent of the lever  22 . 
     Now turning to  FIG. 6B , there is shown an enlarged cross-sectional view of one exemplary embodiment of a switch assembly  80 , itself comprising the actuator assembly  160  which may comprise a set of windings  170 , a permanent magnet  162 , and a pawl  172  with corresponding teeth  176 . Said winding  170  is electrically coupled to said electrical bushings  164  ( FIG. 6A ) and if an electrical potential is applied said windings  170  carry a current. Said permanent magnet  162  is coupled to said commutation sleeve  54  and transmits electromagnetic force to said sleeve  54  when said winding  170  carries an electrical current. Reversing the direction of the current reverses the direction of the electromagnetic force, enabling the sleeve  54  to rotate in a specific direction about the shaft  42 , specified by the user. Furthermore, said pawl  172  may maintain the position of the sleeve  54  relative to the shaft  42 . As illustrated, a spring  174  biases said pawl  172  outward from the shaft  42  to the corresponding teeth  176  integrated in the commutation sleeve  54 . Furthermore, said pawl  174  is ferrous, such that if a current passes through said windings  170  a magnetic field pulls said pawl  172  to compress said spring  174 , detracting said pawl  172  from the teeth  176 , enabling the commutation sleeve  54  to rotate freely with respect to the shaft  42 . Said electromechanical actuator assembly  160  may be used to control the setting of the lever drive assembly  20  by controlling the position of the commutation sleeve  54 . It will be appreciated by those skilled in the art that a number of other mechanical, electrical, electromechanical, and other such means now known or later developed for effectively shifting such a sleeve  54  relative to a shaft  42  so as to change the drive direction may be employed without departing from the spirit and scope of the present invention. 
     To summarize, regarding the exemplary embodiments of the present invention as shown and described herein, it will be appreciated that a multi-directional lever drive system is disclosed and configured for an ergonomic wheelchair. Because the principles of the invention may be practiced in a number of other configurations and contexts beyond those shown and described, it is to be understood that the invention is not in any way limited by the exemplary embodiments, but is generally directed to a multi-directional lever drive system and is able to take numerous forms to do so without departing from the spirit and scope of the invention. It will also be appreciated by those skilled in the art that the present invention is not limited to the particular geometries and materials of construction disclosed, but may instead entail other functionally comparable structures or materials, now known or later developed, without departing from the spirit and scope of the invention. Furthermore, the various features of each of the above-described embodiments may be combined in any logical manner and are intended to be included within the scope of the present invention. 
     While aspects of the invention have been described with reference to at least one exemplary embodiment, it is to be clearly understood by those skilled in the art that the invention is not limited thereto. Rather, the scope of the invention is to be interpreted only in conjunction with the appended claims and it is made clear, here, that the inventor(s) believe that the claimed subject matter is the invention.