The present invention relates to wheelchairs, and particularly to wheelchairs capable of moving the seat and back for tilting and reclining. More particularly, the invention pertains to wheelchairs having legrests capable of being raised to support the legs of the wheelchair user.
Wheelchairs often have a fixed seat consisting of a seating surface and a back frame. The seating surface is usually either horizontal or slightly tilted back, with the front edge of the seating surface slightly higher than the rear edge of that surface. If the wheelchair user sits in the same position in a wheelchair for a long period of time, pressure is continuously applied to the tissue on the portion of the user""s body (buttocks, legs, and/or back) that is bearing the user""s weight in that position. Blood circulation to that tissue will be reduced, and ulcers or other problems can result.
To avoid these problems, it is necessary for people sitting in wheelchairs to shift their body weight from time to time. This is often accomplished by tilting the seat portion of the wheelchair backwards so that the user""s weight is shifted away from the pressure points on the user""s body. Also, the user""s weight can be shifted by reclining the back frame. During the recline process it is preferable to raise the user""s legs by raising the legrest. Power elevating legrests are known, and they are typically driven by linear actuators. A means for raising the legrests on a power wheelchair is disclosed in U.S. Pat. No. 5,297,021 to Koerlin et al.
Where a wheelchair is provided with a legrest, it is desirable to provide the legrest with a swingaway feature so that the legrests can be removed or swung out of the way to make it easier for the user to have access to or egress from the wheelchair. A particularly useful swingaway footrest is disclosed in U.S. Pat. No. 4,790,533 to Okamoto.
One of the problems of elevating legrests is that the legrests are typically not very substantial, giving the wheelchair user an insecure feeling. This is even a problem in power wheelchairs. It would be advantageous if there could be developed a power elevating legrest having robust characteristics. Further, it would be helpful to have a power elevating legrest with a simple to use swingaway feature to enable easy access by the wheelchair user. Another problem with existing power elevating legrests is that the linear actuators used to elevate the legrests typically end up with poorly oriented loading, resulting in badly leveraged configurations. An ideal power elevating legrest would make the maximum use of leverage for an efficient use of power and for the most compact arrangement possible.
The above objects as well as other objects not specifically enumerated are achieved by a wheelchair having a seat frame, legrests pivotally mounted for elevation with respect to the seat frame, and an elevation mechanism. The elevation mechanism includes a latch link having a legrest end attached to the legrest, and a pivot end. Also included is a pivot link having a frame end pivotally connected to the seat frame, and having a latch link end pivotally connected to the pivot end of the latch link. The latch link end of the pivot link and the pivot end of the latch link are pivotally connected through a latch pin. An actuator having a piston movable in forward and rearward directions with respect to the seat frame is provided to pivot the legrests relative to the seat frame, the piston having a forward end that is connected to one of the latch pin, the latch link, and the pivot link.
According to this invention, there is also provided a wheelchair having a seat frame and legrests pivotally mounted for elevation with respect to the seat frame, in which the pivotal mounting of the legrests with respect to the base includes a pivot bracket that enables a legrest pivot pin to be vertically adjusted relative to the seat frame.
Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.