CROSS-REFERENCE TO RELATED APPLICATION

This is a Continuation-in-Part Patent Application of U.S. patent application Ser. No. 10/887,875 filed Jul. 12, 2004 which claims priority from U.S. Provisional Patent Application Ser. No. 60/492,995 filed Aug. 7, 2003 entitled Helical Screw Lift System for an Elevator.

FIELD OF THE INVENTION

This invention relates to a lift system which employs a single helical screw for reciprocal vertical movement of a platform or elevator car between landings.

BACKGROUND OF THE INVENTION

The rapid vertical transportation of persons and materials between multiple floors or landings has long been accomplished by conventional elevator systems which utilize several well known drive systems such as hydraulic systems and traction or winch systems Most of these systems are intended for accommodating multiple passengers between multiple floors such as in office buildings and apartments.

As the proportion of elderly persons continues to increase as a percentage of our society, and as medical technology enables ambulatory dysfunctional persons to live full and healthy lives, there has been an increased interest in the design of a safe, quiet and relatively inexpensive elevator system to assist the elderly or the handicapped with transporting themselves between several levels as would be normally found within a residential home, small institution such as a care facility or the exterior access of public and private buildings.

In many circumstances an access ramp is utilized for access adjacent the exterior entry of a building. Such device requires a substantial horizontal distance to maintain a slope suitable for walking or for wheel chair operation. Where inclement weather is experienced the ramp may need to be covered. Such construction is generally obstructive and unsightly.

Most of the current lift systems are unsuited for conversion to use in a domestic application or for use between two or three floors due to size, cost or the complexity of ancillary operating components as well as the expense of regular servicing to maintain them in a safe working condition. Further, current systems are not generally adaptable to being custom designed for either interior or exterior use in small residential or institutional application.

In the prior art the applicant is aware of U.S. Pat. No. 5,080,200, which issued Jan. 14, 1992 to Gibson for a Ball Screw Elevator Drive System. In this application the elevator is suspended from a pulley journalled at an end of a telescoping lift tube. A screw drive shaft within the fixed tube supports a ball assembly fixedly mounted to the telescoping tube. Rotation of the screw shaft by a motor results in raising or lowering of the ball assembly, the lift tube and with it the elevator.

The applicant is also aware of U.S. Pat. No. 4,742,891, which issued May 10, 1988 to Kunii et al for an Elevator System, where it is disclosed to mount an elevator car on a vertical screw shaft by a rotary element which is mounted on the car and threadably engaged with the screw shaft. Rotation of the screw shaft drives the car in the vertical direction.

The applicant is further aware of U.S. Pat. No. 696,994, which issued Apr. 8, 1902 to Modry for an Electric Elevator. This reference shows an elevator carriage of generally square cross section having a helical screw positioned at each of the corners. Pairs of rollers having their rotational axes generally at right angles to each other are positioned at the comers within the well so as to engage adjacent threads of the screw. Rotation of the screws by an electric motor mounted beneath the carriage result in raising or lowering of the carriage.

It is an object of the present invention to provide an inexpensive, relatively maintenance free elevator primarily for short vertical travel as would normally be found in a residence or small care facility. Such an elevator may be installed within the interior of a building so as to provide alternative access between floors or landings, or at the exterior of a building, to provide easy handicapped access into buildings where the main public access is elevated above ground level.

It is an object to provide an elevator where the car of the elevator is supported on one or more, and in a preferred embodiment, four freely rotating wheels, which rest on the helically inclined upper surface or flight of a single helical screw. Rotation of the helical screw results in rotation of the freely rotatable wheels along the inclined flight thereby vertically translating the elevator car.

SUMMARY OF THE INVENTION

The present invention is an elevator lift system, which employs a single helical screw for reciprocal vertical deployment or translation of a platform or car.

The elevator car is supported on a generally vertically disposed carriage frame which is positioned between and mounted to two vertical spaced apart guide rails. The guide rails are themselves mounted to a vertically separated series of brackets, which are firmly attached to suitable framework in the case of a freestanding lift unit, or to suitable building framework in the case of a conventional elevator.

Pairs of guide wheels are mounted to the side members of the carriage frame, near the upper and lower corners thereof so as to sandwich the vertical guide rails between them.

The carriage frame has one or more and preferably four supporting wheels mounted to a cross member of the carriage so as to engage the helically inclined flight of the single helical screw. In one embodiment, the screw may be positioned medially of the rails and coaxially with the vertical axis of the carriage frame. An elevator car or platform is mounted cantilevered to the supporting carriage frame.

The helical screw is jounialled at its lower end on bearings mounted on a pedestal or base member. A reversible electric motor is mounted to the opposite upper end of the helical screw to selectively rotate the screw to either raise or lower the car supporting carriage frame. In one embodiment, a self locking speed reducer may be employed, mounted between the motor and screw, to inhibit inadvertent reverse rotation of the screw when the electric motor disengages from positive rotation of the screw so as to prevent the inadvertent downward creep of the elevator car.

In summary, the helical screw lift system for an elevator according to the present invention includes:

- a) a rigid vertical frame, the frame including at least one rigid vertical rail;
- b) a single elongate helical screw having an inclined helical flight, the screw rotatably vertically mounted to the frame at opposite ends of the screw;
- c) a selectively actuable drive means mounted to the frame and cooperating with the screw for selectively actuable rotation of the screw so as to selectively reversibly rotate the helical flight of the screw;
- d) a carriage mounted to the vertical rail for vertical translation, for example on vertical translation means such as wheels or rollers, vertically along the rail;
- e) an elevator platform for carrying a load such as cargo and people, rigidly mounted to, so as to be cantilevered from, the carriage;
- f) a rolling means, such as at least one and preferably four wheels or rollers, rigidly mounted cantilevered from the carriage so as to engage and bear down on the helical flight for rolling translation therealong when the screw is rotated about its longitudinal axis,
- g) at least one screw stabilizer mounted to the carriage to maintain alignment of the rolling means with the screw.

The rotational bending moments acting on the rail due to the platform being mounted cantilevered from the carriage are entirely borne by the carriage engaging the rail. A corresponding downward bending moment about a horizontal moment axis through the carriage and the rail is resisted both by an upper translation means component of the vertical translation means mounted on an upper end of the carriage in vertically translatable engagement against a first surface of the rail which is opposite from the platform, and by a lower translation means component of the vertical translation means mounted on a lower end of the carriage in vertically translatable engagement against a second surface of the rail which is opposite from the first surface. The upper and lower ends of the carriage are, respectively, above and below the horizontal moment axis.

In one embodiment not intended to be limiting, the rail is a pair of laterally spaced apart, parallel vertical rails and the vertical translation means are rollers or wheels rotatably mounted on vertically opposite ends of the carriage, and the screw is parallel to and generally equi-distantly spaced between the pair of rails. In a preferred embodiment the rollers or wheels engaging the helical flight are cantilevered from the carriage so as to oppositely disposed relative to the platform., and may be slightly toed inwardly at forward ends of the rollers or wheels relative to an inclined path of the rollers or wheels upwardly along the flight of the screw.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1, is a left side perspective view of a self-supporting elevator according to the present invention.

FIG. 2 is a right side perspective view of the elevator of FIG. 1.

FIG. 3 is a rear elevation view of the self-supporting elevator illustrated in FIG. 1.

FIG. 4 is a sectional view taken on line 4-4 of FIG. 1.

FIG. 5 is a partially cut-away perspective view of a portion of FIG. 4.

FIG. 5a is, in front elevation view, the elevator of FIG. 5 modified to include screw stabilizers.

FIG. 6 is a front elevation enlarged view of a portion of FIG. 5.

FIG. 7 is a schematic electrical diagram according to one embodiment of a two level elevator of the present invention.

FIG. 8 is a schematic electrical diagram according to the embodiment of FIG. 8 illustrating the control arrangement within the elevator car and on the two levels.

FIG. 9a is, in front elevation partially exploded view, one screw stabilizer of the elevator embodiment illustrated in FIG. 5a.

FIG. 9b is, in exploded plan view, the screw stabilizer of FIG. 9a.

FIG. 9c is, in end elevation view, the screw stabilizer of FIG. 9a.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

With reference to the drawing figures, wherein similar characters of reference denote corresponding parts in each view, elevator 10 has a platform or car 12, which is slidably mounted for reciprocal vertical movement on guide rails 16. Rails 16 have a bearing member 16a and side faces 16b. Rails 16 are securely fastened to supporting brackets 18 so as to be secured parallel and spaced apart. Brackets 18 may be mounted by welding or bolting or the like to either external supporting members (not shown) where the elevator is self-supporting, or to building frame members where the elevator is attached to a structure.

Elevator car 12 has a vertically disposed supporting carriage or carriage frame 26 mounted between for translation parallel to guide rails 16. Frame 26 includes side brackets 26a and cross brackets 26b. Guide wheels 30 are mounted in transversely spaced apart pairs at the upper and lower corners of each side bracket 26a. Rail 16 is sandwiched between the upper and lower pairs of wheels 30 with bearing members 16a of the rails in contact with and between the wheels. Four idler rollers 34 are mounted to frame 26. A first pair are mounted in opposed facing relation on cross brackets 26b at a point intermediate between side brackets 26a, and a second pair are mounted in opposed facing relation on cross members 26c, orthogonally, when viewed in plan view, relative to the first pair of idler rollers. The axes of rotation B and Bâ€² of the first pair of idler rollers 34 extend at right angles to the axes of rotation A and Aâ€² of the second pair of idler rollers 34, which pass through the center of rails 16.

Vertical reciprocating movement of both elevator car 12 and supporting frame 26 is accomplished by a single elongate helical screw 36, which is rotatably vertically mounted intermediate rails 16. Screw 36 has a helically inclined flight 36â€² rigidly mounted on a single vertical shaft 36â€³. Flight 36â€² has in one embodiment a 4 inch pitch, that is 4 inches of vertical travel per screw revolution. A 48:1 ratio on flight 36â€², with a 4 horsepower DC motor 42 operating at 3600 R.P.M. equates to 75 revolutions per minute which in turn equates to an elevator travel speed of 25 feet per minute with a torque of 70.02 in/lbs. The horizontal rotational axes A and B of rollers 34 intersect the vertical axis of rotation C of screw 36. Helical screw 36 is positioned so that rollers 34 rests solidly upon the screw flight 36â€². Screw shaft 36â€³ is journalled at its lower end 36a on bearings such as conical, so-called Dodge bearings mounted in a pedestal base 38. A reversible electrical motor 42 is mounted at the opposite upper end of screw shaft 36â€³. Motor 42 is operated to rotate screw 36 to either raise or lower both frame 26 and elevator car 12.

In a preferred embodiment, upper and lower pairs of screw stabilizers 84 are mounted to support brackets 84a, themselves mounted on cross-brackets 26b so as to extend upwardly therefrom. Screw stabilizers 84 in each of the upper and lower pairs are mounted so as to be opposed facing to resiliently snug collars 86a of collar slides 86 in direction D against screw shaft 36â€³ at the upper and lower ends of carriage frame 26. Collar slides 6 are telescopically housed within sleeves 88 for snug sliding translation in direction D under the resiliently biased urging of springs 90. Pins 92 or bolts or the like joumalled through apertures 88b in sleeves 88 slide in slots 86c to limit the travel of the slides 86 so as to bear the opposite ends of the springs against base members 88a of sleeves 88. Consequently, slides 86 may be translated in directions opposite to direction D against the return biasing force of springs 90. Thus each opposed facing pair of screw stabilizers 84 serve to resiliently center any deflection or bowing of shaft 36â€³ and to dampen vibration or vibrating motion of screw shaft 36â€³ during rotation of screw 36. This serves inter alia to quieten operation of the elevator, reduce fatigue of shaft 36â€³ and wear of rollers 34 on flight 36â€², and to keep rollers 34 on their optimum path up along flight 36â€² while under load. In a preferred embodiment slides 86 are made of nylon such as Nyloilâ„¢ and springs 90 are of 0.080 inch diameter wire and have an outside diameter of five eighths of an inch and a length of two inches. Springs 90 are mounted at first ends thereof in sockets 86b in slides 86.

A self locking speed reducer (not shown) may be employed, mounted between the motor and screw, to prevent the angular component of the vertical load transferring to screw 36 from the stationary elevator car 12 through wheels 34 so as to cause reverse rotation of screw 36 and the inadvertent downward creep of elevator car 12.

FIG. 7 schematically illustrates a direct current electrical diagram for operation of the elevator. FIG. 8 illustrates the main operating circuit. FIG. 8 illustrates the circuits from the push-button console 58 in the elevator car. Power is obtained from battery 60, which may be continuously trickle-charged by a trickle charger (not shown). Current flows through circuit breaker 64 to contacts 70, which controls motor 42 for upward movement of the elevator car. Current also travels to contacts 72, which controls downward movement of the elevator car. A horn 78 is activated when the emergency stop button 80 is activated on console 58. Button 80 also immediately cuts operating power to the circuit. Console 58 must be activated through key switch 82 in order to power the circuitry.

As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the spirit or scope thereof. Accordingly, the scope of the invention is to be construed in accordance with the substance defined by the following claims.