Patent Application
20090255739
1. Field of the Invention
This invention relates to a power wheelchair, more particularly to a power wheelchair that is safe to use.
2. Description of the Related Art
Referring to
Although the conventional power wheelchair 1 can achieve its intended purpose, in actual use, it has the following drawbacks:
1. When the front wheels 113 encounter a slope, the front frame 11 inclines unstably, thereby adversely affecting the balance of the seat frame 13, so that the power wheelchair 1 is likely to tip over. Hence, the power wheelchair 1 is unsafe to use.
2. The front frame 11 reacts immediately upon encountering a bump, and the impact is directly transferred to the seat frame 13, thereby adversely affecting the comfort of the user.
Therefore, the object of the present invention is to provide a power wheelchair that can be used safely and comfortably.
According to this invention, a power wheelchair comprises a base frame and a seat frame. The base frame includes front and rear frame members, a pair of front wheels connected rotatably to the front frame member, a pair of rear wheels connected rotatably to the rear frame member, and a pair of mid-wheels connected rotatably to the front frame member and disposed between the front and rear wheels. The rear frame member is connected pivotally to the front frame member. The seat frame is connected to the rear frame member.
Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment of the invention, with reference to the accompanying drawings, in which:
Referring to
The base frame 3 includes front and rear frame members 31, 41, a pair of spaced-apart front wheels 33, a pair of spaced-apart rear wheels 42, and a pair of spaced-apart mid-wheels 32. The front frame member 31, in this embodiment, has a front end provided with a front wheel support rod 3111 and a substantially U-shaped rod 3110 connected pivotally to the front wheel support rod 3111. The U-shaped rod 3110 has left and right side rods 3112 provided respectively at left and right lateral sides of the front frame member 31 and having rod ends 3113 (only one is visible in
The rear frame member 41, in this embodiment, has a front connecting rod 4110 provided at a front end thereof, and left and right side rods 4112 provided respectively at left and right lateral sides of the rear frame member 41 and connected respectively to left and right ends of the connecting rod 4110. The left and right side rods 4112 are further connected pivotally and respectively to the pivot plates 314 in proximity to the front connecting rod 4110 through a pivot shaft 411, so that the front and rear frame members 31, 41 are connected pivotally to each other. The left and right side rods 4112 have rod ends 4113 extending into a rear end of the rear frame member 41 and provided respectively with two rear wheel seats 415 to mount rotatably and respectively the rear wheels 42. The mid-wheels 32 are disposed between the front and rear wheels 33, 42. The left and right side rods 4112 overlap respectively the left and right side rods 3112. Each of the left and right side rods 4112 is provided with a limiting member 413 to limit a pivot movement of the front frame member 31 relative to the rear frame member 41. The limiting member 413 includes two side plates 417 (only one is visible) having top ends screwed respectively to inner and outer faces of the corresponding side rod 4112, and a bottom plate 416 interconnecting the side plates 417 and opposite to the corresponding side rod 4112. The bottom plate 416, the side plates 417, and the corresponding side rod 4112 cooperatively define a limiting space 418. The rod end 3113 of each side rod 3112 extends into the limiting space 418, and is movable upwardly and downwardly within the limiting space 418.
A supporting tube 414 extends upwardly from the rear frame member 41 between the lateral sides thereof. The seat frame 5 is supported by the supporting tube 414.
In this embodiment, the power wheelchair 100 further comprises two motors 34 connected to and disposed below the front frame member 31 so as to drive respectively the mid-wheels 32.
With reference to
With reference to
Hence, regardless of whether the power wheelchair 100 encounters an upward or downward slope, or a bump or an indentation on the surface of the ground, the front and rear wheels 33, 42 and the mid-wheels 32 can move stably and easily on the ground in conformity with the ground surface.
From the aforementioned description, the advantages of the power wheelchair 100 of the present invention may be summarized as follows:
1. When the front wheels 33 encounter a slope, the front frame member 31 pivots immediately to incline with respect to the rear frame member 41. Since the seat frame 5 is supported on the rear frame member 41 by the supporting tube 414, the seat frame 5 does not immediately incline, so that the center of gravity of the seat frame 5 will not suddenly change. As such, the possibility of the power wheelchair 100 being tipped over is minimized, thereby enhancing the safety of the power wheelchair 100.
2. When the front frame member 31 encounters a bump, it rides over the bump. This reaction is not directly transferred to the seat frame 5, so that the power wheelchair 100 is stable and comfortable.
While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is understood that this invention is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretations and equivalent arrangements.
