Wheelchair suspension
View Patent ↗A wheelchair suspension assembly includes a frame, a drive assembly, an anti-tip linkage, a front anti-tip wheel, and a rear anti-tip wheel. The drive assembly includes a drive wheel. The front anti-tip wheel is positioned forward of the drive wheel by the anti-tip linkage. The rear anti-tip wheel is positioned rearward of the drive wheel the anti-tip linkage. The anti-tip linkage couples the front anti-tip wheel to the rear anti-tip wheel such that upward movement of the front anti-tip wheel relative to the frame causes upward movement of the rear anti-tip wheel relative to the frame. The anti-tip linkage includes a front anti-tip pivot arm that is pivotally coupled to the frame, a rear anti-tip pivot arm that is pivotally coupled to the frame, and a connecting link that couples the front anti-tip pivot arm and the rear anti-tip pivot arm.
1. A wheelchair comprising:
a frame;
first and second drive assemblies that each include a drive wheel;
first and second suspension assemblies that each include an anti-tip linkage and a shock absorber with a spring return;
first and second front anti-tip wheels positioned forward of the drive wheels by the first and second anti-tip linkages;
first and second rear anti-tip wheels positioned rearward of the drive wheels by the first and second anti-tip linkages;
the first anti-tip linkage couples the first front anti-tip wheel to the first rear anti-tip wheel such that upward movement of the first front anti-tip wheel relative to the frame causes upward movement of the first rear anti-tip wheel relative to the frame, wherein the first anti-tip linkage includes a first rigid front anti-tip pivot arm that is pivotally coupled to the frame, a first rigid rear anti-tip pivot arm that is pivotally coupled to the frame, and a first rigid connecting link that couples the first rigid front anti-tip pivot arm and the first rigid rear anti-tip pivot arm;
wherein the first shock absorber with spring return is directly coupled to the first rigid rear anti-tip pivot arm and is directly coupled to the frame to bias the first rigid rear anti-tip pivot arm downward relative to the frame;
the second anti-tip linkage couples the second front anti-tip wheel to the second rear anti-tip wheel such that upward movement of the second front anti-tip wheel relative to the frame causes upward movement of the second rear anti-tip wheel relative to the frame, wherein the second anti-tip linkage includes a second rigid front anti-tip pivot arm that is pivotally coupled to the frame, a second rigid rear anti-tip pivot arm that is pivotally coupled to the frame, and a second rigid connecting link that couples the second rigid front anti-tip pivot arm and the second rigid rear anti-tip pivot arm;
wherein the second shock absorber with spring return is directly coupled to the second rigid rear anti-tip pivot arm and is directly coupled to the frame to bias the second rigid rear anti-tip pivot arm downward relative to the frame;
wherein the first drive assembly is pivotally coupled to the frame at a first drive assembly pivot axis that is forward of an axis of rotation of the drive wheel of the first drive assembly;
wherein the first drive assembly is biased downward relative to the frame by a first drive assembly biasing spring that is coupled to the frame;
wherein the second drive assembly is pivotally coupled to the frame at a second drive assembly pivot axis that is forward of an axis of rotation of the drive wheel of the second drive assembly; and
wherein the second drive assembly is biased downward relative to the frame by a second drive assembly biasing spring that is coupled to the frame.
2. The wheelchair of claim 1 wherein the first rigid connecting link is pivotally connected to the first rigid front anti-tip pivot arm and the first rigid rear anti-tip pivot arm and the second rigid connecting link is pivotally connected to the second rigid front anti-tip pivot arm and the second rigid rear anti-tip pivot arm.
3. A wheelchair suspension assembly comprising:
a frame;
a drive assembly that includes a drive wheel;
an anti-tip linkage;
an anti-tip linkage spring;
a front anti-tip wheel positioned forward of the drive wheel by the anti-tip linkage;
a rear anti-tip wheel positioned rearward of the drive wheel the anti-tip linkage;
wherein the anti-tip linkage couples the front anti-tip wheel to the rear anti-tip wheel such that upward movement of the front anti-tip wheel relative to the frame causes upward movement of the rear anti-tip wheel relative to the frame;
wherein the anti-tip linkage includes a front anti-tip pivot arm that is pivotally coupled to the frame, a rear anti-tip pivot arm that is pivotally coupled to the frame, and a connecting link that couples the front anti-tip pivot arm and the rear anti-tip pivot arm;
wherein the anti-tip linkage spring is directly coupled to the rear anti-tip pivot will and is directly coupled to the frame to bias the rear anti-tip pivot arm downward relative to the frame; and
wherein the drive assembly is pivotally coupled to the frame at a first drive assembly pivot axis.
4. The wheelchair suspension assembly of claim 3 wherein the anti-tip linkage spring comprises a shock absorber with a spring return.
5. The wheelchair suspension assembly of claim 3 wherein the front anti-tip pivot arm is rigid.
6. The wheelchair suspension assembly of claim 3 wherein the rear anti-tip pivot arm is rigid.
7. The wheelchair suspension assembly of claim 3 wherein the connecting link is rigid.
8. The wheelchair suspension assembly of claim 3 wherein the drive assembly pivot axis is forward of the axis of rotation of the drive wheel.
9. The wheelchair suspension assembly of claim 3 wherein the drive assembly is biased downward relative to the frame by a drive assembly biasing spring.
10. The wheelchair suspension assembly of claim 3 wherein the connecting link is pivotally connected to the front anti-tip pivot arm and the rear anti-tip pivot arm.