Patent Application
20150323122
This invention relates to a lift mechanism for raising and lowering platforms within a structure, such as a recreational vehicle or trailer.
Recreational vehicles, fifth wheel and cargo trailers often have automated lifts that raise and lower decks and platforms from a storage position for use as a bed, storage area or equipment lift within their interior space. While these automated lifts are popular and have convenient features, the mechanisms used to raise and lower the platforms have heretofore suffered from a variety of operational and manufacturing problems. An array of hydraulic, pneumatic and electro-mechanical actuation devices (“actuators”) have been employed with varying degrees of success, including screw drives, chains, rack and pinions, telescoping rams, as well as various linkage arrangements.
The present invention provides a platform lift that employs flexible polyurethane timing belts as flexible rack members in a rack and pinion type drive mechanism. Each embodiment of the platform lift includes a horizontal platform or deck shiftably mounted to a frame upright, post or column that is raised and lowered by movement of a “drive” carriage shiftably disposed within the frame upright. The carriage is driven along the flexible polyurethane timing belt disposed within the frame upright by a reversible electric motor that turns the pinion gear inside the carriage. The timing belt passes through a carriage and is trained around the pinion and between two idle rollers in a serpentine fashion.
The flexibility of the timing belt and the serpentine engagement of the timing belt around the idle rollers and the pinion ensures positive actuation of the platform between its raised and lowered positions and eliminates the chance of slippage. The use of a flexible timing belt also provides manufacturing and maintenance advantages. Because timing belts are durable, resist stretch and require little lubrication, the actuator of this invention requires little care or maintenance once installed. The timing belts are easily mounted and readily accessible inside the frame upright. The reduced weight of the timing belts over traditional rigid metal racks means smaller and less costly drive motors and components can be used.
These and other advantages of the present invention will become apparent from the following description of an embodiment of the invention with reference to the accompanying drawings.
The drawings illustrate an embodiment of the present invention, in which:
In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific preferred embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is understood that other embodiments may be utilized and that logical, structural, mechanical, electrical and material composition changes may be made without departing from the spirit or scope of the invention. To avoid detail not necessary to enable those skilled in the art to practice the invention, the description may omit certain information known to those skilled in the art. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims.
The drawings depict multiple embodiments of the platform lift of this invention. Each embodiment adapted for a particular application, such as a bed lift in recreational vehicles, a wheel chair lift for handi-capable vehicles or platform lift for raising motorcycles and ATVs into cargo trailers and the like. In each embodiment of the platform lift, the horizontal platform or deck is shiftably mounted to a frame upright, post or column and raised and lowered by a rack and pinion type drive mechanism using a flexible polyurethane timing belt disposed within the frame upright as a flexible rack member. The deck or platform carried is by a motor drive traveler that traverses along the length of the timing belt to raise and lower the platform up and down the frame upright.
As shown, bed lift 100 includes a support frame 110. Support frame 110 is generally built into the interior walls of the RV or trailer or otherwise fastened to the super structure of the RV or trailer. Alternatively, frame 110 may be modified in other embodiments to be a free standing structure within the living or working interior of an RV or trailer. Support frame 110 generally includes four upright corner columns or posts 112 and a pair of side cross members 116 and end cross members 118 each connecting the top ends of two corner posts. Corner posts 112 are generally affixed to the interior wall of the RV or trailer (not shown) by screws or similar fasteners. Corner posts 112 are lengths of metal C-channel, which have a hollow interior with an inward facing vertical channel 113. Side and end cross members 116 and 118 are lengths of square aluminum or steel tubing welded or fastened to the tops of corner posts 112.
A bed deck 120 is suspended between corner posts 112 for movement between a lowered (
An actuator assembly 140 raises and lowers bed deck 120 between its raised position and lowered position. Actuator assembly 150 uses a flexible rack and pinion mechanism to vertically reciprocate two of the slide carriages 130 within adjacent corner posts 112. Actuator assembly 140 includes a pair of flexible polyurethane timing belts 150 mounting within the interior 111 of adjacent corner posts 112. Timing belts 150 act as a flexible rack member in a rack and pinion type drive mechanism. Timing belts 150 are of conventional design and construction, such as the kind manufactured and distributed by Polytech Design, Inc. Of Clifton, N.J. Timing belts 150 are used due to their strength, flexibility and stretch resistance. Polyurethane timing belts are also light weight, durable and require little lubrication. Although, steel reinforced polyurethane timing belts are preferred, any other light weight, durable, stretch resistant timing belt may be employed within the teaching of this invention. Each timing belt 150 has a plurality of raised teeth, which extend lateral across one face of the belt. Generally, timing belts 150 have imbedded reinforcing fibers (not shown), which prevent longitudinal stretch of the belts. Timing belts 150 extend through the interior of corner posts 112. The end of the belts pass through openings 115 at the ends of the corner posts and are secured to the outside of corner posts 112 by clamping plates 158 and fastener 159. As shown, clamping plates 158 allow for linear adjustment of the position of timing belts 150 relative to its position within corner post 112. With the ends affixed to the corner posts 112, timing belts 150 extends loosely through the interior of corner posts 112. Actuator assembly 140 uses two of slide carriages 130 acting as “drive” carriages operatively associated with timing belts 150 to raise and lower bed deck 120. While only two of the four slide carriages 130 are used in this embodiment as drive carriages, in other embodiments, all four side carriages may be used as “drive” carriages to raise and lower bed deck 120. The “drive” carriages 130 are similar in design and structure to the other slide carriages, but include a pinion 160 and two idle rollers 162 rotatably mounted within U-shaped bracket 132, which allows the carriage to be operatively propelled along the length of the timing belt 150. Timing belt 150 passes through drive carriage 130 and is trained around pinion 160 between two idle rollers 162 in a serpentine fashion. As shown in
Actuator assembly 140 also includes an electric motor assembly 170, which drives pinion 160. Motor assembly 170 includes a reversible electric motor 172, gear box 174 and drive shaft 176. Motor 170 is a conventional reversible AC or DC electric motor although any suitable drive motor may be used as desired. Motor assembly 170 is mounted to the underside of deck frame 122 and turns drive shaft 156 to simultaneously drive pinions 160, which propel drive carriage 130 along the length of timing belts 150 thereby moving bed deck 120 between its raised and lowered positions. Motor 170 turns pinions 160 in one direction to raise deck 120 and in the opposite direction to lower the deck.
As best shown in
The present invention provides several significant benefits over conventional platform lifts. In addition, the flexibility of the timing belts and the serpentine engagement of the timing belts around the idle rollers and pinion ensure positive actuation of the platform between its raised and lowered positions and eliminates the chance of slippage. The use of timing belts in the actuator of this invention also provides manufacturing and maintenance advantages in slide-out room applications. Because timing belts are durable, resist stretch and require little lubrication, the actuator of this invention requires little care or maintenance once installed. In the rare case that adjustment or replacements are needed, the majority of the actuator's components are readily accessible. The timing belts are easily mounted and readily accessible inside the frame uprights, column and corner posts. The mounting channels and clamping plates allow the slack timing belts to be quickly and readily tightened once operatively mated through the drive carriage. More importantly, the mounting channels and clamping plates allow for the adjustment of the timing belts relative to the column or corner post. The reduced weight of the timing belts over traditional rigid metal racks means smaller and less costly drive motors and components can be used.
The embodiment of the present invention herein described and illustrated is not intended to be exhaustive or to limit the invention to the precise form disclosed. It is presented to explain the invention so that others skilled in the art might utilize its teachings. The embodiment of the present invention may be modified within the scope of the following claims.
