LIFT DEVICE

Abstract: A lift device which is easily prefabricated, safe, free from maintenance and inspection, and installable for home-use, and finds such wide applications as escaping means in an emergency and a simple portable footstool. This device comprises a strap-like rail wound in a screw shape and shielded bearings arranged so as to be fitted to the strap-like rail, said rail and said shielded bearings being mounted on and fitted to either the inner periphery of a longer cylinder forming an outer shell or the outer periphery of an inner shorter cylinder telescopically provided with a proper space from the inner periphery of the longer cylinder, said shorter cylinder being mounted thereon with a lift cage through thrust bearings, and said lift cage being locked against rotation and provided thereon with a motor transmittingly rotating the shorter cylinder to thereby effect lifting, and further, relates to a lift device wherein the above-described lift devices are combined in multiple-telescopic structure, thereby allowing cylinders to project telescopically for lifting operation. This lift device comprises a strap-like rail and bearings screw-fitted to the strap-like rail, and is unique in social contribution, etc., in terms of safety, maintainability, modularity and the wide applications.

Description: The present invention relates to a lift device comprising bearings and a strap-like rail that are designed to screw fit in each other. Prior Art: Conventionally, a sliding device termed as a so-called ball screw has been known. The sliding device has a wide range of applications, such as an XY recorder in a measuring machine, and a feeding device for a machine tool. However, it is more or less impossible to use such a sliding device for a lift device as it is. In other words, the structure comprises a ball and a screw that are in smooth sliding engagement, and a lubricant used to lubricate the engagement is essentially required along the full sliding distance of the screw shaft portion, and therefore even if an expandable bellows are used as a protecting and dust proofing cover for the sliding device, or this is implemented by a solid telescopic cover, it is totally impossible to cover a long device such as a lift. Furthermore, although the shaft is usually rotated to drive the sliding device, deflection resulting from a manufacturing precision constitutes a cause for low rotation speed, and even if a motor is mounted on a nut side member, there is a limit to manufacturing a long shaft side member. The current technology of connecting a plurality of short shaft members to each other is not accurate enough to produce such a long shaft, and hence no long shaft based upon that technology has been realized. Moreover, as to a method for supporting a lift cage, in order to adopt a two-end support instead of a one-end support, design strategies including synchronization of rotation are required. However, this serves only to complicate the structure and make it difficult to realize an ideal device. The state of the art is also illustrated by the JP-A-57 77185 and GB-A-658 022. Disclosure of the Invention : The present invention provides a lift device comprising bearings and a strap-like rail that are designed to screw fit in each other, characterized in that the bearings are constituted as shielded bearings which are mounted in a circumferential thread fashion at a proper pitch on a proper number of pillars provided inside an outer shell cylinder, that a short cylinder is threadingly inserted into said outer shell cylinder around the outer circumference of which short cylinder a strap-like rail is curvedly wound so as to screw fit into said bearings, that said short cylinder is rotated by a motor mounted on a frame to support said short cylinder at a vertical central position via thrust bearings, and that engaging iron plates are provided on said frame embracing the shielded bearings, said iron plates also being designed to act as a cam groove for stopping the rotation of said frame, as well as maintaining said short cylinder at the central position. Thus, this construction serves to compensate for the drawbacks of the prior art lift device. Brief Description of the Drawings : Fig. 1 is a plan view, partially cut-away, showing a construction in which four pillars are provided on the inner surface of an outer shell cylinder with bearing being mounted thereon in a thread-like fashion, and in which a short cylinder is provided inside the outer shell cylinder around which a strap-like rail is wound in a male thread-like fashion, Fig. 2 a partially cut-away perspective view of the above construction, Fig. 3 a partially cut-away perspective view of a construction that is opposite to the above, Fig. 4 a partially cut-away perspective view showing a construction adopting a principle of gravity-fall and in which a lift cage is provided so as to protrude outwardly, and Fig. 5 a partially cut-away perspective view showing a multi-thread construction. Figures 3 to 5 do not constitute embodiments of the invention. Best Mode for Embodying the Present Invention: The present invention will be described in detail with reference to the accompanying drawings. In Fig. 1, four pillars 2, 2, ..., are provided along the inner circumferential surface of an outer shell cylinder 1 with a slight gap being provided therebetween, and shielded bearings 3, 3, ..., are mounted at a proper pitch on the inward side of the pillars so as to form circumferential threads on an inscribing circle of the pillars. A short cylinder 5 is inserted into the outer shell cylinder around the outer circumference of which a strap-like rail 4 is curvedly wound so as to screw fit into the shielded bearings, and this short cylinder is suppoted on a frame 6 via thrust bearings at a vertical central position. Side iron plates 7, 7, ..., are provided at the four pillars so as to hold bearings from the sides. These iron plates also serve to maintain the short cylinder 5 at the center with respect to an XY direction, as well as to stop the rotation that would otherwise be caused by the reaction force of the rotation of the short cylinder 5 caused in turn by a rotational driving motor 9 integrally mounted on a lift cage 8 set on the upper thrust bearings. A pinion gear 10 and a large gear 11 are mounted on the motor 9 shaft and the short cylinder 5, respectively, whereby the rotation of the motor is transmitted to the short cylinder 5. An outer door is provided at a position corresponding to a door 12 provided on the lift cage 8 between the pillars 2, 2 of the outer shell cylinder for exit. Fig. 3 shows a construction opposite to the one shown in Fig. 2, in which the male and female relationship between the bearings and the rail is reversed. In this cases groove cam rails K, K, K are formed in a lift cage 8' at least at three positions thereof, and small diameter bearings B, B, ..., are linearly mounted at the inside diameter positions of a strap-like rail 4' provided on the inner surface of the outer shell cylinder so that they fit into the groove to thereby function to stop the rotation of the lift cage, as well as to maintain the same at the central position. The diameter of those bearings can be designed to be so small that the rotation of the shielded bearings 3', 3', ..., is not affected by those small-diameter bearings. By way of example, a motor 9' in Fig. 2 is a motor capable of reducing speed by planetary gears and is shown as a motor with a brake that can be vertically direct coupled. Fig. 4 shows the same construction as that shown in Fig. 3 except that an opening groove M is formed by slit cutting vertically the strap-like rail on the outer shell cylinder at a proper position so that a stay F is extended from a inner spacer R so as to protrude from the outer shell cylinder with a necessary carrier being provided on the stay. In Fig. 4, there is no motor mounted, while there are provided the outer shell cylinder, a brake shoe S, and a lever L for activating the brake shoe. Thus, a lowering device for emergency escape is illustrated. In addition, as to the central position maintaining mechanism, small-diameter bearings B', B', B' are mounted on the outer circumference of the short cylinder at three positions thereof in such a manner as to thrust the inner circumference of the outer cylinder. An outer door is hinged so as to constitute an entrance through which a rotational body can be inserted at any time. Fig. 5 shows a mechanism developed based on the ideas shown in Figs. 1 and 2. In this mechanism, large and small cylinders are fitted one within another in a multi-thread fashion so that they protrude telescopically. A rotational driving motor 9'' is mounted inside a central small-diameter cylinder, and the top surface of the small-diameter cylinder is fixed to the uppermost portion of telescopic type cover cylinder Z, Z, Z (in this case, three stages), which are expanded by slit grooves H, H, H, and locking pins P, P, P, whereby a rotation stop means is effected. Casters are mounted on this structure to constitute a movable footstool, which is based on the development from the basic ideas. Industrial Application: Thus, the lift mechanism according to the present invention is so safe that no maintenance and inspection is practically required, and can be adopted as a unit lift for home use, or outdoor use. The compact mechanical section allows the lift mechanism to be used for a lift for every purpose.

Claims: A lift device comprising bearings and a strap-like rail (4, 4') that are designed to screw fit in each other, characterized in that the bearings are constituted as shielded bearings (3) which are mounted in a circumferential thread fashion at a proper pitch on a proper number of pillars (2) provided inside an outer shell cylinder (1), that a short cylinder (5) is threadingly inserted into said outer shell cylinder (1) around the outer circumference of which short cylinder a strap-like rail (4, 4') is curvedly wound so as to screw fit into said bearings, that said short cylinder (5) is rotated by a motor (9) mounted on a frame (6) to support said short cylinder (5) at a vertical central position via thrust bearings, and that engaging iron plates (7) are provided on said frame embracing the shielded bearings, said iron plates (7) also being designed to act as a cam groove (K) for stopping the rotation of said frame (6), as well as maintaining said short cylinder (5) at the central position.

Inventors: TATUMI SIGEZOU, TATUMI, SIGEZOU
Applicants: TATUMI SIGEZOU, TATUMI, SIGEZOU
Application year: 1991
Main classification: B66B9
IPC codes: B66B9, B66B7