Adjustable anti-tip wheels for power wheelchair

• US 6,923,278 B2
• Filed: 05/06/2002
• Issued: 08/02/2005
• Est. Priority Date: 05/06/2002
• Status: Active Grant

• Current Assignee: Pride Mobility Products Corporation
• Original Assignee: Pride Mobility Products Corporation
• Inventors: Mulhern, James P., Leitner, George Lewis Jr., Levi, Ronald J.
• Primary Examiner(s): SHRIVER II, JAMES A
• Application Number:
  US10/139,191
• Publication Number:
  US 20030205420A1
• Time in Patent Office: 1,184 Days
• Field of Search: 180/65.1, 180/907, 180/6.5, 180/6.48, 180/209, 280/304.1, 280/293, 280/767, 280/250.1, 297/423.26, 297/423.34, 297/423.36, 297/DIG.4, 297/DIG.10
• US Class Current: 180/65.1
• CPC Class Codes: A61G 2203/14 Joysticks
• CPC Class Codes: A61G 5/043 Mid wheel drive
• CPC Class Codes: A61G 5/06 with obstacle mounting facilities, e.g. for climbing stairs, kerbs or steps
• CPC Class Codes: A61G 5/1089 Anti-tip devices
• CPC Class Codes: B60G 2300/24 Wheelchairs
• CPC Class Codes: B60G 2300/402 Extra load carrying wheels, e.g. tag axles
• CPC Class Codes: B60G 2800/912 Attitude Control; levelling control
• CPC Class Codes: Y10S 180/907 Motorized wheelchairs

Abstract

A power wheelchair with front anti-tip wheels for substantially eliminating partial tips of the wheelchair is described. The anti-tip wheels are attached to the end of an extension arm which is attached to the frame of the wheelchair. A spring connects the anti-tip wheels with the frame at a second point. The spring tends to hold the anti-tip wheels in a neutral position at a predetermined height above the ground. A lowering mechanism is provided which positions the anti-tip wheels in a position engaged with or just above the ground. A retaining system holds the anti-tip wheels on or near the ground until the user or a release trigger device releases the retaining system, at which time the anti-tip wheels return to the neutral position. While the retaining system is disengaged, the wheels are free to rise in response to an upward force in order to climb over an obstacle in the wheelchair'"'"'s path of travel.

Claims

1. A power wheelchair comprising:

a frame;

a seat mounted on the frame;

a motor for controlling and driving at least one of a pair of drive wheels;

an anti-tip wheel assembly pivotally attached to the frame and supporting one or more anti-tip wheels at a variable height from the ground, the anti-tip wheel assembly tending to hold the one or more anti-tip wheels in a predetermined neutral position;

a lowering mechanism attached to the frame for positioning the one or more anti-tip wheels in a near ground position against the tendency of the anti-tip wheel assembly;

a retaining system for holding the one or more anti-tip wheels in the near ground position; and

a quick release mechanism to release the retaining system for allowing the one or more anti-tip wheels to return to the neutral position.

2. The power wheelchair of claim 1 wherein the lowering mechanism and the retaining system are a unified anti-tip wheel positioning assembly.

3. The power wheelchair of claim 1 wherein the lowering mechanism and the retaining system are distinct.

4. The power wheelchair of claim 1 wherein the anti-tip wheel assembly comprises at least one arm pivotally attached to the frame and extending therefrom, the one or more anti-tip wheels being rotatably connected to an end of the at least one arm opposite the frame, and at least one spring connecting to the at least one arm between the frame and the one or more wheels, the at least one spring being connected to the frame, the size and tension of the spring at least partially determining the neutral position where the anti-tip wheel assembly tends to hold the one or more anti-tip wheels.

5. The power wheelchair of claim 1 wherein the retaining system comprises at least one gear and gear shaft assembly having

a gear shaft rotatably supported by the frame,

a gear disengageably associated with the gear shaft, and

a locking rod having teeth thereon, the teeth being engaged with the gear, and the lowering shaft being pivotally attached to the at least one arm, and

a ratchet for limiting rotation of the gear shaft to one direction,

the gear shaft being disengagebly associated with the gear and ratchet such that the gear, ratchet and gear shaft are in rotational unison while engaged.

6. The power wheelchair of claim 5 wherein the quick release mechanism comprises a solenoid electronically controlled by a release trigger device, the solenoid being rotatably attached to the gear shaft such that actuation of the solenoid causes the gear shaft to become engaged and disengaged with the gear or ratchet.

7. The power wheelchair of claim 5 wherein the lowering mechanism comprises an independent suspension member for a drive wheel, the independent suspension member being fixedly attached to the anti-tip wheel assembly and tending to pivot about a central pivot point with respect to the frame in response to deceleration the wheelchair such that the one or more anti-tip wheels are moved downwardly.

8. A power wheelchair comprising:

a frame;

a seat mounted on the frame;

a pair of drive wheels;

a drive motor for controlling and driving at least one of the pair of drive wheels, each drive wheel being supported by a suspension member, each suspension member being pivotally mounted to the frame and responsive to changes in drive motor torque;

an anti-tip wheel arm mounted to each independent suspension member;

an anti-tin wheel mounted on each anti-tip wheel arm; and

a retaining system for holding the anti-tip wheels in a fixed position upon pivoting of the independent suspension members in response to changes in drive motor torque; and

a release trigger device adapted to disengage the retaining system.

9. The power wheelchair of claim 8 further comprising:

a supporting assembly rigidly connected to the frame;

a strut connected to the anti-tip wheel arm;

the spring being coiled about the strut; and

the strut slidedly supported by the supporting assembly.

10. The power wheelchair of claim 8 wherein the release trigger device automatically sends a signal for releasing the retaining system in response to detection of an obstacle in the path of travel of the wheelchair.

11. A power wheelchair comprising:

a frame;

a seat mounted on the frame;

a pair of drive wheels;

a drive motor for controlling and driving at least one of the pair of drive wheels, each drive wheel being supported by a suspension member, each suspension member being pivotally mounted to the frame and responsive to changes in drive motor torque;

an anti-tip wheel arm mounted to each independent suspension member;

an anti-tip wheel mounted on each anti-tip wheel arm; and

a retaining system for holding the anti-tip wheels in a fixed position upon pivoting of the independent suspension members in response to changes in drive motor torque; and

a locking rod having teeth, the locking rod being attached to each anti-tip wheel arm and slidedly engaged with a supporting assembly, the supporting assembly being rigidly attached to the frame,

a gear engaged with the teeth of the locking rod,

a gear shaft associated with the gear, and

a ratchet associated with the gear shaft such that the gear shaft is limited to rotation in one direction when engaged therewith.

12. The power wheelchair of claim 11 wherein a solenoid is rotatably attached to the gear shaft such that actuation of the solenoid causes engagement and disengagement of the gear shaft and the gear.

13. The power wheelchair of claim 11 wherein a solenoid is rotatably attached to the gear shaft such that actuation of the solenoid causes engagement and disengagement of the gear shaft and the ratchet.

14. A wheelchair comprising:

a frame;

a seat mounted on the frame;

a drive motor for driving at least one of a pair of drive wheels;

an anti-tip wheel assembly pivotally attached to the frame and supporting one or more anti-tip wheels at a variable height from the ground;

an anti-tip wheel motor for driving an anti-tip wheel lowering mechanism; and

control circuits for controlling the anti-tip wheel motor, the control circuits comprising,

an up control circuit for operating the anti-tip wheel motor in an up direction,

a down control circuit for operating the anti-tip wheel motor in a down direction, and

a safety interlock control circuit that operates to prevent any drive voltage from operating the anti-tip wheel motor under predetermined conditions.

15. The wheelchair of claim 14 wherein the control circuits further comprise:

an up limit control circuit that stops the anti-tip wheel motor at a predetermined limit of upward movement of the anti-tip wheels, and

a down limit control circuit that stops the anti-tip wheel motor at a predetermined limit of downward movement of the anti-tip wheels.

16. The wheelchair of claim 14, wherein the up control circuit comprises:

a first manual control element,

a first time delay circuit element, and

a first switching circuit to energize the anti-tip wheel motor in the up direction.

17. The wheelchair of claim 16 wherein the safety interlock control circuit comprises:

a logic gate having a first input connected to the first manual control element, and

a second switching circuit to create a short circuit across the anti-tip wheel motor.

18. The wheelchair of claim 17 wherein the down control circuit comprises:

a second manual control element,

a second time delay circuit element, and

a third switching circuit to energize the anti-tip wheel motor in the down direction,

wherein a second input to the logic gate is connected to the second manual control element.

19. The wheelchair of claim 18 wherein the control circuits further comprise:

an up limit control circuit that stops the anti-tip wheel motor at a predetermined limit of upward movement of the anti-tip wheels,

a down limit control circuit that stops the anti-tip wheel motor at a predetermined limit of downward movement of the anti-tip wheels.

20. The wheelchair of claim 19 wherein the up limit control circuit comprises:

a first automatic control element that is actuated at the predetermined limit of upward movement of the anti-tip wheels, and

a first disabling circuit that disables the first switching circuit.

21. The wheelchair of claim 20 wherein the down limit control circuit comprises:

a second automatic control element that is actuated at the predetermined limit of downward movement of the anti-tip wheels, and

a second disabling circuit that disables the third switching circuit.

22. The wheelchair of claim 18 wherein actuation of both the up and down control circuits drives the logic gate to create a short circuit across the motor.

23. The wheelchair of claim 22 wherein the logic gate is an exclusive NOR gate.

24. The wheelchair of claim 18 wherein, the first switching circuit is in electrical communication with a first voltage source through the first manual control element and across a first capacitor,

the first switching circuit comprises a first transistor and a first relay, the first relay supplying a drive voltage to a first side of the anti-tip wheel motor that drives the anti-tip wheel motor in the up direction when the first manual control element is closed, the first manual control element provides a high logical input to the logic gate when closed, and

the second switching circuit comprises a second transistor and a second relay, the second switching circuit being connected to an output of the logic gate, the second relay creating the short circuit across the anti-tip wheel motor when the logic gate provides a first output, and the second relay opening the short circuit across the anti-tip wheel motor when the logic gate provides a second output.

25. A wheelchair comprising:

a frame;

a seat mounted on the frame;

a drive motor for driving at least one of a pair of drive wheels;

an anti-tip wheel assembly pivotally attached to the frame and supporting one or more anti-tip wheels at a variable height from the ground;

an anti-tip wheel motor for driving an anti-tip wheel lowering mechanism; and

control circuits for controlling the anti-tip wheel motor, the control circuits comprising

means for operating the anti-tip wheel motor in an up direction,

means for operating the anti-tip wheel motor in a down direction,

means for preventing any drive voltage from operating the anti-tip wheel motor under predetermined conditions,

means for stopping the anti-tip wheel motor at a predetermined limit of upward movement of the anti-tip wheels, and

means for stopping the anti-tip wheel motor at a predetermined limit of downward movement of the anti-tip wheels.

26. The wheelchair of claim 25, wherein the means for operating the anti-tip wheel motor in the up direction comprises:

a first manual control element,

means for creating a first time delay, and

means for energizing the anti-tip wheel motor in the up direction.

27. The wheelchair of claim 26 wherein the means for preventing any drive voltage from operating the anti-tip wheel motor under predetermined conditions comprises:

means for providing a logical output to a means for creating a short circuit across the anti-tip wheel motor, the means for providing a logical output having a first input connected to the first manual control element.

28. The wheelchair of claim 27 wherein the means for operating the motor in the down direction comprises:

a second manual control element,

means for creating a second time delay,

means for energizing the anti-tip wheel motor in the down direction, and

means for providing a second input to the means for providing a logical output.

29. The wheelchair of claim 28 wherein the means for stopping the anti-tip wheel motor at a predetermined limit of upward movement of the anti-tip wheels comprises:

means for automatically actuating at the predetermined limit of upward movement of the anti-tip wheels, and

means for disabling the means for energizing the anti-tip wheel motor in the up direction.

30. The wheelchair of claim 29 wherein the means for stopping the anti-tip wheel motor at a predetermined limit of downward movement of the anti-tip wheels comprises:

means for automatically actuating at the predetermined limit of downward movement of the anti-tip wheels, and

means for disabling the means for energizing the anti-tip wheel motor in the down direction.

31. A power wheelchair comprising:

a frame;

a seat mounted on the frame;

a pair of drive wheels, each drive wheel mounted to said frame about a rotational axis;

a motor mounted to the frame driving at least one of said drive wheels;

a wheel assembly disposed to one side of said rotational axis for stabilizing said frame about said rotational axis;

a suspension arm pivotally mounted to the frame and mounted to said wheel assembly at one end thereof, said suspension arm responsive to torque applied by said drive motor and effecting translation of said wheel assembly; and

an active restraint engaging said suspension arm and locking the wheel assembly in a fixed pivotal position with respect to the frame at a set torque level.

32. The power wheelchair according to claim 31 wherein said active restraint facilitates lowering of said wheel assembly.

33. The power wheelchair according to claim 31 wherein said active restraint includes intermeshing gear teeth to lock the wheel assembly at said near ground position.

34. A power wheelchair comprising:

a frame;

a seat mounted on the frame;

a pair of drive wheels,

at least one pitch stabilizing wheel;

a motor for controlling and driving each of said drive wheels;

a suspension system mounting said pitch stabilizing wheel to said frame and enabling resilient translation of said pitch stabilizing wheel relative to said frame, and

a wheel restraint having intermeshing teeth disposed between said frame and said suspension system and operative to lock said pitch stabilizing wheel relative to said frame.

35. The power wheelchair according to claim 34 wherein said wheel restraint facilitates lowering of said pitch stabilizing wheel.

36. The power wheelchair according to claim 34 wherein said wheel restraint is operative to lock said pitch stabilizing wheel at a near ground position.

37. The power wheelchair according to claim 34 wherein said wheel restraint comprises a ratchet having the plurality of teeth, said ratchet disposed in combination with said frame, and wherein at least one tooth is disposed in combination with said suspension system and engages said teeth of said ratchet, said teeth being configured to provide unidirectional retention such that said suspension system is locked in response to a negative torque and released in response to a positive torque applied to one or more of said drive wheels.

38. The power wheelchair according to claim 34 wherein said wheel restraint employs a ratchet having the plurality of teeth, said ratchet disposed in combination with said suspension system, and at least one tooth disposed in combination with said frame and engaging said teeth of said ratchet, said teeth being configured to provide unidirectional retention such that said wheel is locked in response to a negative torque and released in response to a positive torque applied to one or more of said drive wheels.