Seat elevating mechanism for chair

[0001] The present invention relates to a seat elevating mechanism for chair designed to provide a supporting force that helps old men and patients to get up from or sit on a chair effortlessly.

[0002] An old man or a patient with weak legs and slow movement has difficulty in sitting on a chair safely and effortlessly, and therefore frequently needs help of an attendant to sit on the chair. It is even more laborious for the old man or the patient having injured or weak legs to get up from the chair, particularly when there is not an attendant.

[0003] There are chairs with an elevating seat available in the market designed for the aged and some patients. The elevating seats of these conventional chairs are slightly higher than that of other normal chairs, and are therefore not comfortable for sitting. Since the conventional elevating seats are normally elevated using an air pump, the users still need to exert strength at two legs to get up from the elevated seats. Another disadvantage of the conventional elevating seats is the seats are forward and downward inclined when being elevated, preventing the users from stably sitting thereon. The conventional chairs with elevating seats are therefore not safe and inconvenient for use.

[0004] A primary object of the present invention is to provide a seat elevating mechanism for chair, in which the seat of the chair is electrically driven to elevate, so that a user may stably sit thereon while the seat is gradually elevated and horizontally moved forward, and may get up from the chair effortlessly when the elevated seat reaches at a desired height.

[0005] The seat elevating mechanism for chair according to the present invention includes a chair, a two-piece seat, a seat support, and a telescopic lifter. The seat support includes a mounting bracket fixedly mounted to a front side of the chair, and a seat-board supporting frame having front and rear portions for supporting front and rear seat boards, respectively, to a top thereof. The front and the rear portion of the seat-board supporting frame are pivotally connected to one another at two laterally spaced pivoting points. The telescopic lifter may be actuated to push the rear portion of the seat-board supporting frame upward, so that the seat-board supporting frame and the seat boards thereon are elevated and horizontally moved forward, allowing a user stably sit thereon to get up easily.

[0006] In the seat elevating mechanism for chair according to the present invention, the rear portion of the seat-board supporting frame is always in a horizontal position in the course of elevating or lowering, allowing the user to stably sit thereon.

[0013] Please refer to FIGS. 1 and 2. The present invention relates to a seat elevating mechanism for a chair 10. As shown, the set elevating mechanism mainly includes a two-piece seat 20 consisting of a front and a rear seat board 21, 22, a seat support 30, and a telescopic lifter 40.

[0014] The seat support 30 includes a mounting bracket 31 fixedly mounted to a front side of the chair 10 at a predetermined position, a seat-board supporting frame 32 for supporting the two seat boards 21, 22 to a top thereof, two laterally corresponded horizontal arms 33 fixedly connected at one end to the fixed mounting bracket 31, and two links 34.

[0015] The whole seat-board supporting frame 32 is pivotally connected at a front side to the fixed mounting bracket 31, so as to pivotally turn about two pivoting points 51 relative to the mounting bracket 31. The seat-board supporting frame 32 includes a front and a rear portion 321, 322 that are pivotally connected to one another at two laterally spaced pivoting points 52, and respectively support the front and the rear seat boards 21, 22 thereon.

[0016] Each of the two links 34 has a first end pivotally connected to a free end of one of the horizontal arms 33 to turn about a pivoting point 53, and a second end pivotally connected to the rear portion 322 of the seat-board supporting frame 32 to turn about a pivoting point 54, such that the pivoting points 51 for the front side of the seat-board supporting frame 32 and the fixed mounting bracket 31, the pivoting points 52 for the front and the rear portion 321, 322 of the seat-board supporting frame 32, and the pivoting points 53, 54 for the two ends of the links 34 together form four points of a parallelogram.

[0017] The telescopic lifter 40 includes a base 41 pivotally connected to the rear portion 322 of the seat-board supporting frame 32 at a predetermined point, and an extendable pipe 42 having an outer end pivotally connected to a rear bottom crossbar 11 of the chair 10 at a predetermined point. When the telescopic lifter 40 is actuated, it pushes the rear portion 322 of the seat-board supporting frame 32 upward and thereby elevates the seat 20 supported on the seat-board supporting frame 32 while moving the seat 20 forward, enabling a person sitting on the seat 20 to get up easily.

[0018] Please refer to FIG. 3. When the extendable pipe 42 of the telescopic lifter 40 is extended, the seat-board supporting frame 32 is elevated. Since the above-mentioned four pivoting points 51, 52, 53, and 54 form four points of a parallelogram, the rear portion 322 of the frame 32 is always in parallel with the horizontal arms 33, which are fixedly connected to the mounting bracket 31. And, since the horizontal arms 33 are horizontally fixedly mounted on the chair 10, the rear portion 322 of the seat-board supporting frame 32 is always in a horizontal position, allowing a user, particularly an old man to sit on the seat 20 stably. When the telescopic lifter 40 gradually pushes the seat 20 upward, the front portion 321 of the seat-board supporting frame 32 is turned about the pivoting points 51 at the front side of the seat-board supporting frame 32, bringing the rear portion 322 to gradually move forward while being elevated, and enabling the old man to get up from the seat more easily.

[0019] In practical use of the chair 10, a back cushion 12 is attached to a back of the chair 10, and front and rear seat cushions 13, 14 are separately attached to the two seat boards 21, 22 of the seat 20, so that the chair 10 is more comfortable for sitting. To help an old man to sit on the rear seat cushion 14, first elevate the seat-board supporting frame 32 to a desired height, as shown in FIG. 5, so that the old man's hips are in contact with and slightly seated on the rear seat cushion 14. Then, the telescopic lifter 40 is operated to retract the extendable pipe 42, so that the seat-board supporting frame 32 and the rear seat cushion 14 are gradually lowered for the old man to sit down effortlessly.

[0020] The telescopic lifter 40 is a known mechanism, and the extendable pipe 42 is driven to move by an electric motor. When the extendable pipe 42 of the telescopic lifter 40 is caused to retract, a weight must be applied to the telescopic lifter 40 to lower the seat-board supporting frame 32. This design makes the seat elevating mechanism of the present invention safer for use. This type of telescopic lifter 40 is referred to as a passively retractable telescopic lifter 40 and has been widely supplied in the market for many years. More specifically, when the extendable pipe 42 of the telescopic lifter 40 is gradually retracted, a distance by which the seat-board supporting frame 32 is elevated with the telescopic lifter 40 is gradually reduced at the same time. At this point, an overall weight of the user, the frame 32, and the base 41 of the telescopic lifter 40 would cause the seat-board supporting frame 32 to move downward and finally reach a fully lowered horizontal position, as shown in FIG. 4. However, in practical design of the chair 10, it is possible for the seat-board supporting frame 32 to lower under only the weight of the supporting frame 32 and the base 41 when the extendable pipe 42 is operated to retract.

[0021] It is preferable to have two laterally corresponded links 34, so that the whole seat elevating mechanism of the present invention may be moved in a stable manner. A switch 15 is provided to a lower front of one armrest 16 of the chair 10 for conveniently controlling the operation of the telescopic lifter 40 by a user.

[0022] In brief, the seat elevating mechanism for a chair according to the present invention uses simple linkage for the seat to gradually elevate while maintaining in a horizontal position, so that an old man or a patient may be stably and effortlessly moved to an almost upright position. Moreover, the seat is moved forward while being elevated, allowing the old man or the patient to stand up more easily. Therefore, the present invention actually provides a power-controlled elevating chair very suitable for the aged.