Wheelchair suspension

• US 7,040,429 B2
• Filed: 10/10/2001
• Issued: 05/09/2006
• Est. Priority Date: 10/10/2001
• Status: Expired due to Term

• Current Assignee: Invacare Corporation
• Original Assignee: Invacare Corporation
• Inventors: Molnar, James H.
• Primary Examiner(s): Johnson, Brian L.
• Assistant Examiner(s): Campbell, Kelly E
• Application Number:
  US09/974,348
• Publication Number:
  US 20040060748A1
• Time in Patent Office: 1,672 Days
• Field of Search: 280/5.2, 280/5.22, 280/5.26, 280/513, 280/5.32, 280/DIG.10, 280/250.1, 280/304.1, 280/220, 180/907, 180/65.1, 180/8.2, 297/DIG.4
• 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 5/063 with eccentrically mounted wheels
• CPC Class Codes: A61G 5/10 Parts, details or accessories
• CPC Class Codes: A61G 5/1078 with shock absorbers or other suspension arrangements between wheels and frame
• CPC Class Codes: B60G 2300/24 Wheelchairs
• CPC Class Codes: B60G 5/01 the set being characterised by having more than two successive axles
• CPC Class Codes: Y10S 180/907 Motorized wheelchairs
• CPC Class Codes: Y10S 297/04 Wheelchair

Abstract

A wheelchair suspension having plurality of pivoting linkages to lift and retract a front castor assembly to facilitate traversing an obstacle or rough terrain. In this regard, a wheelchair suspension having a frame member and at least one a pivoting assembly is provided. The pivoting assembly has, for example, a first linkage pivotally coupled to the frame member and a second linkage pivotally coupled to the frame member. At least one front caster assembly is coupled to the first and second linkages wherein upward pivotal movement of the first linkage causes the caster assembly to undergo upward vertical movement and upward pivotal movement of the second linkage causes the caster assembly to undergo lateral movement inward toward the wheelchair.

Claims

1. A wheelchair suspension comprising:

a frame member;

a pivoting assembly having;

a first linkage pivotally coupled to the frame member; and

a second linkage pivotally coupled to the frame member;

a drive assembly coupled to the first linkage;

at least one rear caster; and

at least one front caster assembly coupled to the first and second linkages wherein upward pivotal movement of the first linkage causes the caster assembly to undergo upward vertical movement and upward pivotal movement of the second linkage causes the caster assembly to undergo lateral movement toward the drive assembly.

2. The suspension of claim 1 wherein the first linkage comprises a plurality of sub-linkages that are coupled together.

3. The suspension of claim 2 wherein the drive assembly is coupled to a first sub-linkage and the front caster assembly is coupled to a second sub-linkage.

4. The suspension of claim 2 further comprising a stop configured to limit the pivotal movement of the first linkage by engaging a first sub-linkage limiting the pivotal movement in a first direction and engaging a second sub-linkage limiting the pivotal movement in a second direction.

5. The suspension of claim 1 further comprising a stop configured to limit the pivotal movement of the first linkage.

6. The suspension of claim 1 wherein the first linkage is pivotally coupled to the frame member by a first pivotal connection and the second linkage is pivotally coupled to the frame member by a second pivotal connection and wherein the second pivotal connection is laterally offset from the first pivotal connection.

7. The suspension of claim 6 wherein the second pivotal connection is laterally offset from the first pivotal connection in a direction toward the front caster assembly.

8. The suspension of claim 1 wherein the first linkage has an overall length that is greater than the second linkage.

9. The suspension of claim 8 wherein the first linkage is pivotally coupled to the frame member at a location that that is vertically higher than the location that the second linkage is pivotally coupled to the frame member.

10. A wheelchair suspension comprising:

a frame member having first and second sides;

a first pivoting assembly coupled to the first side;

a second pivoting assembly coupled to the second side;

at least one front caster assembly coupled to each of the first and second pivoting assemblies;

first and second drive assemblies respectively coupled to the first and second pivoting assemblies wherein each of the first and second drive assemblies is configured to respectively pivot first and second pivoting assemblies so that the at least one front caster assembly coupled to the first and second pivoting assemblies undergoes vertical movement and lateral movement towards the respective first and second drive assemblies.

11. The suspension of claim 10 wherein the first and second pivoting assemblies each comprise a plurality of linkages that are coupled to the at least one front caster assembly and the frame member.

12. The suspension of claim 11 wherein a first linkage is pivotally coupled to the frame member by a first pivotal connection and a second linkage is pivotally coupled to the frame member by a second pivotal connection and wherein the second pivotal connection is laterally offset from the first pivotal connection.

13. The suspension of claim 12 wherein the first linkage has an overall length that is greater than the second linkage.

14. The suspension of claim 13 wherein the first linkage is pivotally coupled to the frame member at a location that that is vertically higher than the location that the second linkage is pivotally coupled to the frame member.

15. The suspension of claim 12 wherein the second pivotal connection is laterally offset from the first pivotal connection in a direction toward the front caster assembly.

16. A suspension comprising:

a main frame;

first and second side frame assemblies, each side frame assembly comprising;

interfaces for releasably attaching the side frame assembly to the main frame;

a pivoting assembly having;

a first link pivotally coupled to the frame member; and

a second link pivotally coupled to the frame member;

a drive assembly coupled to the first link;

at least one rear caster; and

at least one front caster assembly coupled to the first and second links wherein upward pivotal movement of the first link causes the caster assembly to undergo upward vertical movement and upward pivotal movement of the second link causes the caster assembly to undergo lateral movement toward the drive assembly.

17. The suspension of claim 16 wherein the first link is pivotally coupled to the frame member by a first pivotal connection and the second link is pivotally coupled to the frame member by a second pivotal connection and wherein the second pivotal connection is laterally offset from the first pivotal connection.

18. The suspension of claim 16 wherein the first link has an overall length that is greater than the second link.

19. The suspension of claim 16 further comprising a resilient means coupled to and between the side frame and the first link.

20. The suspension of claim 16 wherein the front caster assembly comprises a coupling to the first and second linkages and for allowing pivotal motion of the first and second linkages wherein upward pivotal motion of the first linkage raises the front caster assembly and upward pivotal motion of the second linkage retracts the front caster assembly.

21. The wheelchair assembly of claim 20, wherein the pivoting assembly comprises an upper link and a lower link being pivotally mounted to the at least one front caster and to the frame at respective upper pivot axes, the lower link being pivotally mounted to the at least one front caster and to the frame at respective lower pivot axes, the distance between the upper pivot axes being different than the distance between the lower pivot axes, and one of the upper and lower links comprising a drive wheel mount for mounting the at least one main drive wheel to the frame.

22. A wheelchair suspension defining a forward direction and a rearward direction of the wheelchair, the suspension comprising

a frame,

at least one main drive wheel for engaging the ground,

at least one front caster for engaging the ground forward of the main drive wheel, and

a pivoting assembly mounting the front caster to the frame so that the front caster can move upwardly and rearwardly when encountering an object, the pivoting assembly comprising an upper link and a lower link, the upper link being pivotally mounted to the front caster and to the frame at respective upper pivot axes, the lower link being pivotally mounted to the front caster and to the frame at respective lower pivot axes, the distance between the upper pivot axes being different than the distance between the lower pivot axes, and one of the upper or lower links comprising a drive wheel mount.

23. The wheelchair suspension of claim 22, further comprising at least one rear caster for engaging the ground rearward of the main drive wheel, the front caster and rear caster being mounted with respect to the frame so that the front caster, the main drive wheel and the rear wheel caster can all engage level ground at the same time, and further wherein the front caster is biased to normally remain in contact with the ground.

24. The wheelchair suspension of claim 23, further comprising a motor for driving the main drive wheel, and further wherein the torque generated at the drive wheel during is sufficient to overcome the bias on the front caster whereby the caster moves upwardly and rearwardly.

25. The wheelchair suspension of claim 22, wherein the front caster is biased to remain in contact with the ground.

26. The wheelchair suspension of claim 25, further comprising a motor for driving the main drive wheel, the torque created at the drive wheel is sufficient to overcome the bias on the front caster whereby the front caster moves upwardly and rearwardly.

27. The wheelchair suspension of claim 22, wherein the frame further includes a frame member for positioning between two side frame assemblies, the two side frame assemblies being configured for releasable mounting to the frame member so that the wheelchair can be disassembled and reassembled.

28. The wheelchair of claim 22, wherein the distance between the upper pivot axes is greater than the distance between the lower pivot axes.

29. The wheelchair of claim 22 further comprising at least one motor for driving the at least one main drive wheel.

30. The wheelchair of claim 29 further comprising a controller for controlling the at least one motor.

31. A wheelchair suspension defining a forward direction and a rearward direction of the wheelchair, the suspension comprising

a frame,

at least one main drive wheel for engaging the ground,

at least one front caster for engaging the ground forward of the main drive wheel, the front caster being biased to normally remain in contact with the ground,

a pivoting assembly mounting the front caster and at least one main drive wheel to the frame so the front caster can move upwardly and rearwardly when encountering an object, and

a motor for driving the main drive wheel, the torque created at the drive wheel by the motor during rapid acceleration of wheelchair being sufficient to overcome the bias on the front caster whereby the front caster moves upwardly and rearwardly in response to rapid acceleration of the wheelchair.

32. The wheelchair suspension of claim 31, wherein the frame further includes a frame member for positioning between two side frame assemblies, the two side frame assemblies being configured for releasable mounting to the frame remember so that the wheelchair can be easily disassembled and reassembled.

33. The wheelchair of claim 31, wherein the distance between the upper pivot axes is greater than the distance between the lower pivot axes.

34. The wheelchair of claim 31 further comprising at least one motor for driving the at least one main drive wheel.

35. The wheelchair of claim 34 further comprising a controller for controlling the at least one motor.

36. A wheelchair suspension comprising:

a frame, and

a pivoting assembly comprising a first linkage means linking at least one front caster to the frame via first and second upper pivoting means, a second linkage means linking the at least one front caster to the frame via first and second lower pivoting means, and the first and second upper pivoting means separated from each other by a first distance and the first and second lower pivoting means separated from each other by a second distance, the first and second distances being different from each other, and one of the first or second linkage means further configured to mount a drive wheel to the frame;

further comprising a drive wheel means coupled to the first linkage means;

further comprising a drive means for generating torque at the drive wheel means during rapid acceleration, said torque generating a moment arm sufficient to overcome to cause the front caster to move upwardly and rearwardly toward the drive wheel means.

37. A wheelchair suspension comprising:

a frame, and

a pivoting assembly comprising a first linkage means linking at least one front caster to the frame via first and second upper pivoting means, a second linkage means linking the at least one front caster to the frame via first and second lower pivoting means, and the first and second upper pivoting means separated from each other by a first distance and the first and second lower pivoting means separated from each other by a second distance, the first and second distances being different from each other, and one of the first or second linkage means further configured to mount a drive wheel to the frame;

further comprising at least one motor means for driving the drive wheel;

further comprising an electronic controller means for controlling the at least one motor means;

wherein the at least one motor means is configured to generate a torque in response to a rapid acceleration signal from the electronic controller means that causes the at least one front caster to move vertically and toward the drive wheel so as to drive the wheelchair over obstacles or rough terrain.