Suspension structure for wheelchair

A suspension structure for a wheelchair generally includes movable arm that serve to connect driving wheels with frame of a wheelchair, sliding unit is further provided for enabling the movable arm to movably connect with a front cantilever of the wheelchair. By such arrangements, in case that the wheelchair of the present invention encounters a raised ground, or similar barriers of the like, the front cantilever will work with the movable arm to raise front jockey wheels, whereas the driving wheels firmly catches the ground, such that enables the wheelchair to the pass the barrier smoothly without difficulties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a suspension structure for a wheelchair, and more particularly to a suspension structure comprised of front cantilever, movable arm and sliding assembly, which are provided between front jockey wheel, driving wheel and frame of a wheelchair.

2. Description of the Prior Arts

A conventional wheelchair with suspension structure as shown inFIGS. 1 and 2(as disclosed by U.S. Pat. No. 6,199,647), wherein between a frame10, driving wheel11and front jockey wheel12is provided with plural compression springs13, the compression springs13serve to timely raise or lower down the front jockey wheel12and the driving wheel11upon encountering a raised ground, or similar barrier of the like, so as to enable the wheelchair to overcome the barrier. However, there are some deficiencies will be found in real operation:

First, the front jockey wheel12and the driving wheel11are independently structured, and which are adjusted by the compression springs13corresponds to road condition, in this case, upon encountering barrier, the body of the wheelchair will substantially tilt and swing sharply (caused by the compression and expansion of the compression springs), it is unsafe for user to sit on an unstable wheelchair. Moreover, the respective compression springs13also have elastic fatigue problem.

Second, when faced with a barrier and the front jockey wheel12is stopped by resistance (when the front jockey wheel abuts against slopping surface of the barrier), since the suspension structures of the front jockey wheel12and that of the driving wheel11are not interactively connected, the friction of the driving wheel with the road can not be increased correspondingly, in this case, the wheelchair is not easy to roll over the barrier.

Third, since the compression springs13serve as suspension structure for the driving wheel11and the front jockey wheel12, the suspension structure is very complexly designed as comprising at least a pair of front cantilevers14, a pair of drive rods15, four pieces of compression spring13and shafts16, a pair of stop rods17. Thus the cost is pretty high.

The present invention has arisen to mitigate and/or obviate the afore-described disadvantages of the conventional suspension structure for a wheelchair.

SUMMARY OF THE INVENTION

The primary object of the present invention is to provide a suspension structure for wheelchair, which generally includes movable arm that serves to connect driving wheels with frame of a wheelchair, sliding unit is further provided for enabling the movable arm to movably connect with a front cantilever of the wheelchair. By such arrangements, upon encountering a raised ground, or similar barriers of the like, the front cantilever will work with the movable arm to raise the front jockey wheel, whereas the driving wheels firmly catches the ground, so as to enable the wheelchair to the pass the barrier smoothly without difficulties.

The present invention will become more obvious from the following description when taken in connection with the accompanying drawings, which shows, for purpose of illustrations only, the preferred embodiments in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring toFIGS. 3–5, wherein a suspension structure for wheelchair is shown and comprised of movable arm30, front cantilever40and a sliding assembly50which are respectively provided between frame20, driving wheel31and front jockey wheel41.

The frame20is main body of a wheelchair and serves to carry respective components of the wheelchair. The front side of the frame can be provided with a first ear21and a second ear22, the rear end of the frame can be equipped with rear wheel23.

The movable arm30is swingingly coupled to the first ear21of the frame20. An end of the movable arm30is connected to the driving wheel31, the driving wheel31is driven by a motor32to move the wheelchair.

The front cantilever40, a first end of which is equipped with the front jockey wheel41and a second of the front cantilever40is fixed to the second ear22of the frame, thus the front cantilever40is able to swing.

The sliding assembly50includes a pair of slide plates51and a shaft52. Each of the slide plates51is defined with a slot511, the slides plates51are oppositely arranged in corresponding way and then a pair of bolts53are used to make the movable arm30slidably connect to the front cantilever40, and thus the bolts52are able to slide within the slot511, the shaft52is slidably disposed between the two bolts52.

Based on the above-mentioned structure, the wheelchair in accordance with the present invention is able to roll over barriers60easily and smoothly.

When running on level road, the front jockey wheel41and the driving wheel31keep contacting the ground. However, as shown inFIGS. 5 and 6, initially the front jockey wheel41will contact the sloping surface61of the barrier60upon encountering a barrier60and is stopped by the surface61(as shownFIG. 5). At this moment, the driving wheel31keeps driving the wheelchair to move forward, with the pushing force generated by the driving wheel31, the front jockey wheel41and the front cantilever40will rise upward smoothly. And then, via the sliding assembly50, the front cantilever40raises an end of the movable arm30connecting to the sliding assembly50, whereas another end of the movable arm30connecting to the driving wheel31is lowered accordingly. In other words, with the first ear21serving as a fulcrum of the movable arm30, an end of the connecting30rises and the other end of the same is lowered.

It will be noted that when the end of the movable arm30connecting to the driving wheel31is lowered, the friction of the driving wheel31on the road will be increased (the driving wheel will abut closely against the road), such that the driving wheel is able to drive the wheelchair efficiently to move it forward, by this way, the front jockey wheel41rises continuously and rolls over the sloping surface61of the barrier60. In real operation, initially the front jockey wheel41rises a little smoothly and then followed by a quick rise, so as to roll over the barrier60.

After the front jockey wheel41overcome the sloping surface61of the barrier60(as shown inFIGS. 7 and 8), the height difference between the front jockey wheel41and the driving wheel31can be adjusted by slide movement of the movable arm30and the front cantilever40with respect to the sliding assembly50. By this way, both the front jockey wheel41and the driving wheel31are allowed to keep contacting the road. Wherein the shaft52is able to make the movable arm30and the front cantilever40which located in the sliding plates51slide smoothly. After rolling over the barrier60and roll on level road again, the movable arm30and the front cantilever40will return to their original position with the help of the sliding assembly50. In other words, with the sliding assembly50to couple the movable arm30with the front cantilever40and make them to slide, the suspension structure in accordance with the present invention is able to enable wheelchair to overcome the barrier.

Referring again toFIG. 3, between the movable arm30and the frame20can be provided with a buffer70which can be made of elastic rubber, the buffer70serves as a stop piece and a shock-absorber to smooth the swing of the movable arm30, and make the ridding comfortable. The buffer70is useful but not essential.

The suspension structure of the present invention is simple but effective as only being comprised of movable arm30, front cantilever40and sliding assembly50, which requires no spring and steel rope, and no worry about elastic fatigue.

In addition, the rear wheel of the wheelchair in accordance with the present invention is designed as having no suspension device, this design has no influence on the wheelchair in overcoming barrier, but it discomforts the rider. In view of this, the present invention offers a simple shock-absorbing method for reference. Referring toFIG. 9, wherein a cantilever80is provided on the rear side of the frame20, and between the cantilever80and the rear side of the frame20a shock-absorbing spring is disposed for connecting them together. A first end of the cantilever80can be provided with rear wheel23, whereas a second end of the same is pivotally connected to the rear side of the frame20, such that the cantilever80is able to swing pivotally. An ear81can be provided on the rear side of the cantilever80. The shock-absorbing spring comprises shaft82and spring83, the spring82is mounted onto the shaft83. An end of the cantilever82is connected to the ear81of the cantilever80, and another end of the cantilever82is connected to mounting bracket84on the rear side of the frame20, and then a locking pin85is used to prevent disengagement of the shaft82from the mounting bracket84. By this way, the rear wheel23can be adjusted precisely corresponds to the real road condition.