초록 ▼

An anti-tip system is adapted for use in a powered wheelchair for purposes of curb-climbing and ride stability. The anti-tip system includes at least one anti-tip wheel, a suspension arm for mounting the anti-tip wheel and a pair of links coupling the suspension arm to the main structural frame of t

An anti-tip system is adapted for use in a powered wheelchair for purposes of curb-climbing and ride stability. The anti-tip system includes at least one anti-tip wheel, a suspension arm for mounting the anti-tip wheel and a pair of links coupling the suspension arm to the main structural frame of the wheelchair. Each of the links is pivotally mounted to the main structural frame of the wheelchair about a first pivot point and is pivotally mounted to the suspension arm about a second pivot point. In a first embodiment of the anti-tip system, the links include an upper and lower link, wherein the upper link is extensible to facilitate angular displacement of the suspension arm to permit rearward displacement of the anti-tip wheel in response to an externally applied load.

대표청구항 ▼

What is claimed is: 1. A power wheelchair comprising: a body; a drive wheel; a motor arranged to drive the drive wheel; a suspension element bearing the drive wheel and arranged to pitch relative to the body in response to acceleration of the drive wheel by the motor; a pair of anti-tip links pivot

What is claimed is: 1. A power wheelchair comprising: a body; a drive wheel; a motor arranged to drive the drive wheel; a suspension element bearing the drive wheel and arranged to pitch relative to the body in response to acceleration of the drive wheel by the motor; a pair of anti-tip links pivoted to the body; a suspension arm pivoted to the pair of anti-tip links; an anti tip wheel rotatably mounted on the suspension arm; and an actuator in operative pivotal connection with the suspension element and at least one of the anti-tip links, the actuator responsive to motion of the suspension element relative to the body so as to cause pivoting of the anti-tip links relative to the body. 2. A wheelchair according to claim 1, wherein the actuator comprises a third link pivotally connected to the suspension element at one end of the third link and pivotally connected to the at least one anti-tip link at the opposite end of the third link. 3. The wheelchair according to claim 1, wherein said anti-tip wheel is at a first end of the wheelchair, and said actuator is so arranged that movement of said suspension element in response to acceleration of the wheelchair towards said first end moves said anti-tip links in a sense to raise the suspension arm and the anti-tip wheel. 4. The wheelchair according to claim 3, wherein the first end of the wheelchair is the front in a principal direction of motion of the wheelchair. 5. The wheelchair according to claim 1, wherein said suspension element comprises a transmission through which said motor drives said drive wheel. 6. The wheelchair according to claim 1, wherein at least one of said anti-tip links is variable in length, said variable length link extending or retracting to facilitate angular displacement of said suspension arm and displacement of said anti-tip wheel in a longitudinal direction of the wheelchair. 7. The wheelchair according to claim 6, wherein said variable length link is arranged to permit longitudinal displacement of said anti-tip wheel in response to an externally applied force on said anti-tip wheel. 8. The wheelchair according to claim 7, wherein said variable length link and said anti-tip wheel have a rest position, wherein said variable length link is arranged to change length away from said rest position to permit said longitudinal displacement of said anti-tip wheel in response to an externally applied force on said anti-tip wheel, and wherein said variable length link and said anti-tip wheel are arranged to return to said rest position when said externally applied force is removed. 9. The wheelchair according to claim 8, wherein said longitudinal displacement is permitted in a longitudinal direction toward said body. 10. The wheelchair according to claim 9, wherein said longitudinal displacement toward said body is accompanied by upward displacement of said anti-tip wheel. 11. The wheelchair according to claim 8, wherein said rest position is an end position of the change of length of said variable length link. 12. The wheelchair according to claim 8, further comprising a spring arranged to return said variable length link and said anti-tip wheel to said rest position. 13. The wheelchair according to claim 6 wherein said pair of anti-tip links includes an upper link and a lower link, said upper link being extensible and said lower link having a fixed length, said suspension arm rotating about its point of pivoting to said lower link to effect longitudinal displacement of said anti-tip wheel. 14. The wheelchair according to claim 1, wherein the positions at which said anti-tip links are pivoted to said body and to said suspension arm are arranged such that as said suspension arm rises relative to said body said suspension arm rotates relative to said body, and a lower end of said suspension arm bearing said anti-tip wheel moves towards said body. 15. The wheelchair according to claim 14, wherein an upper one of said anti-tip links is longer than a lower one of said anti-tip links. 16. The wheelchair according to claim 14, wherein the positions at which said anti-tip links are pivoted to said body are closer together than the positions at which said anti-tip links are pivoted to said suspension arm. 17. The wheelchair according to claim 1, wherein one of the anti-tip links is a crank link having a fulcrum where it is pivoted to the body, a first arm extending from the fulcrum to the suspension arm, and a second arm extending from the fulcrum, the actuator acting on the second arm. 18. The wheelchair according to claim 17, wherein the second arm of the crank link extends down from the fulcrum. 19. The wheelchair according to claim 18, wherein the actuator is a third link pivotally connected to the suspension element at a position relatively below the pivotal connection between the suspension element and the body and is pivotally connected to the second arm of the crank link. 20. The wheelchair according to claim 1, which is a mid-wheel drive wheelchair having at each side a drive wheel with a respective suspension element, pair of anti-tip links, suspension arm, anti-tip wheel, and actuator operatively connected therewith. 21. A power wheelchair comprising: a body; a drive wheel; a motor arranged to drive the drive wheel; a suspension element bearing the motor and arranged to pitch relative to the body in response to the torque applied to the drive wheel by the motor; a pair of anti-tip links pivoted to the body; a suspension arm pivoted to the pair of anti-tip links; an anti-tip wheel rotatably mounted on the suspension arm; and an actuator in operative connection with the suspension element and one of the anti-tip links, the actuator responsive to motion of the suspension element relative to the body so as to cause pivoting of the anti-tip links relative to the body; wherein one of the anti-tip links is a crank link having a fulcrum formed at the position where the link is pivoted to the body, a first arm extending from the fulcrum to the suspension arm, and a second arm extending from the fulcrum in an opposite sense from the first arm, the actuator acting on the second arm; and wherein the crank link is a lower one of the pair of anti-tip links. 22. A powered wheelchair comprising: a main structural frame; a drive train assembly, said drive train assembly pivotally mounting to the main structural frame and pivotable relative to said frame when applying torque to at least one drive wheel; a bracket fixed to said drive train assembly; and an anti-tip system comprising at least one anti-tip wheel; a suspension arm for mounting said anti-tip wheel; and a pair of links, each of said links pivotally mounting to said main structural frame at one end of the link and pivotally mounting to said suspension arm at the other end of the link, at least one of said links coupled to said drive train assembly such that said pair of links pivot in response to rotation of said drive train assembly; and an actuator in operative pivotal connection with the bracket at one end and in operative pivotal connection at its opposite end with one of the pair of links, the bracket translating the motion of the drive train assembly relative to the frame, through the actuator, to cause a pivoting of the anti-tip links relative to the frame. 23. The powered wheelchair of claim 22, wherein said anti-tip system is mounted at one end of said main structural frame. 24. The powered wheelchair of claim 23, wherein said anti-tip system is mounted at a front end of the frame with respect to normal use of said powered wheelchair. 25. The powered wheelchair of claim 22, wherein at least one link is variable in length and said anti-tip wheel is mounted at a lower end of said suspension arm, such that said anti-tip wheel moves towards or away from said frame as said variable-length link varies in length. 26. The powered wheelchair of claim 25, wherein said anti-tip wheel moves towards or away from said frame in response to an externally applied force on said anti-tip wheel. 27. The powered wheelchair of claim 26, wherein said anti-tip wheel is arranged to move inwardly toward said main structural frame away from a rest position. 28. The powered wheelchair of claim 27, wherein said anti-tip wheel moves upwardly as it moves inwardly. 29. The powered wheelchair of claim 25, wherein said variable length link includes first and second link segments relatively movable with respect to one another for varying said length dimension. 30. The powered wheelchair according to claim 22, wherein the operative coupling of said drive train assembly to the link, through the actuator, is in response to movement of said drive train assembly when torque is applied to the drive wheels. 31. The powered wheelchair according to claim 22, further comprising a third link, the third link pivotally connected to the bracket and the actuator such that movement of the drive train assembly in response to torque applied by the drive train assembly to the drive wheel is transmitted through the third link to cause pivoting of the anti-tip links in a sense to raise the suspension arm and the anti-tip wheel. 32. The powered wheelchair according to claim 22 wherein a lower link of said pair of links is a crank link. 33. The powered wheelchair according to claim 32, wherein the crank link has a fulcrum, a first crank arm and a second crank arm, said fulcrum pivotally mounting about a first pivot axis to said main structural frame, said first crank arm linked to said drive train assembly, and said second crank arm pivotally mounting about a second pivot axis to said suspension arm. 34. A powered wheelchair comprising: a main structural frame; a drive train assembly, said drive train assembly pivotally mounting to the main structural frame and pivotable relative to said frame when applying torque to at least one drive wheel; and an anti-tip system comprising: at least one anti-tip wheel; a suspension arm for mounting said anti-tip wheel; and a pair of links, each of said links pivotally mounting to said main structural frame at one end of the link and pivotally mounting to said suspension arm at the other end of the link, at least one of said links coupled to said drive train assembly such that said pair of links pivot in response to rotation of said drive train assembly, at least one of said links being variable in length such that said suspension arm rotates and said anti-tip wheel moves relative to said frame as said variable-length link varies in length; and wherein said pair of links includes an upper and lower link, said upper link being extensible and said lower link having a fixed length, said suspension arm rotating about said point of pivoting of said suspension arm to said lower link to effect displacement of said anti-tip wheel towards said frame as said upper link extends. 35. A powered wheelchair comprising: a main structural frame; a drive train assembly, said drive train assembly pivotally mounting to the main structural frame and pivotable relative to said frame when applying torque to at least one drive wheel; and an anti-tip system comprising at least one anti-tip wheel, a suspension arm for mounting said anti-tip wheel, and a pair of links, each of said links pivotally mounting to said main structural frame at one end of the link and pivotally mounting to said suspension arm at the other end of the link, at least one of said links coupled to said drive train assembly such that said pair of links pivot in response to rotation of said drive train assembly, at least one of said links being variable in length such that said suspension arm rotates and said anti-tip wheel moves relative to said frame as said variable-length link varies in length, wherein said variable length link comprises first and second link segments and a spring-biased tension rod connecting said segments. 36. The powered wheelchair according to claim 35, wherein said first link segment includes a rod-connecting end having a longitudinal bore for accepting and aligning said tension rod, said second link segment connected to one end of said tension rod, and a coil spring in compression disposed between said rod-connecting end of said first link segment and the other end of the tension rod. 37. A vehicle comprising: a frame; a pair of main drive wheels mounting to and supporting the frame about a rotational axis; a drive train assembly pivotally mounting to the main structural frame and capable of bi-directional rotation about said pivot axis when torque is applied to the drive wheels; and an active anti-tip system including at least one anti-tip wheel; a suspension arm for mounting said anti-tip wheel; a pair of anti-tip links, each of said links pivotally mounted to said main structural frame at one end and pivotally mounted to said suspension arm at the other end, at least one of said links coupled to said drive train assembly such that the links pivot in response to rotation of said drive train assembly an actuator in operative pivotal connection with a suspension element and one of the anti-tip links such that movement of the suspension element in response to torque applied to the drive wheels by the drive train assembly is transmitted through the actuator to cause pivoting of the anti-tip links in a sense to raise the suspension arm and the anti-tip wheel. 38. The vehicle according to claim 37, wherein at least one of said links is variable in length, said anti-tip wheel is positioned at a lower end of said suspension arm, and changes in the length of said variable length link are associated with longitudinal displacement of said anti-tip wheel. 39. The vehicle according to claim 38, wherein said anti-tip wheel is displaceable longitudinally in response to an externally applied force on said wheel. 40. The vehicle according to claim 39, wherein said anti-tip wheel is displaceable inwardly toward said main structural frame from a rest position. 41. The vehicle according to claim 40, wherein said pair of links includes an upper link and a lower link, said upper link being extensible and said lower link having a fixed length, said suspension arm rotating about its point of connection with said lower link to effect displacement of said anti-tip wheel toward said frame as said upper link extends. 42. The vehicle according to claim 37, wherein a lower one of said pair of links is a crank link having a fulcrum, a first crank arm and a second crank arm, said fulcrum pivotally mounting said crank link about a first pivot axis to said frame, said second arm pivotally connected to said actuator. 43. A vehicle comprising: a body; at least one drive wheel; a motor arranged to drive the drive wheel; a suspension element bearing the motor and arranged to pitch relative to the body in response to the torque applied to the drive wheel by the motor; a pair of anti-tip links pivotally mounted on the body at one end and their opposite end projecting from the body away from the drive wheel; a suspension arm pivoted to the pair of anti-tip links; an anti-tip wheel mounted on the suspension arm; and a third link operatively pivotally connected to the suspension element at one end thereof and to one of the anti-tip links at the opposite end thereof, the third link responsive to motion of the suspension element relative to the body so as to cause pivoting of the anti-tip links relative to the body about their pivotal mounting.