Sheave array arrangement for elevator

Abstract: A sheave array arrangement for an elevator, which is arranged in the upper section of a building and is adapted to suspend a car and a counterweight of the elevator, having such an array arrangement that a plurality of ropes paid out from a sheave section for suspending the car to the car are converged in the vicinity of a vertical line passing though the center of gravity of the car.

Description: The invention relates to an elevator comprising: a) a car and a counterweight suspended by ropes; b) and a sheave arrangement guiding said ropes; c) with the ropes as paid out from a first sheave arrangement section for suspending said car being at a smaller maximum horizontal distance than the ropes as paid out from an opposite second sheave arrangement section for suspending said counterweight and being attached to said car in the vicinity of a vertical line passing through the center of gravity of said car. Such an elevator is known from the document NL-A-98 437. The sheave arrangement of the known elevator comprises a first sheave paying out four ropes for suspending the car and a second sheave, having a stepped circumference, paying out four ropes for suspending the counterweight. The two sheaves are arranged with parallel axes at different heights. The four moving ropes engage one of the sheaves first and the other sheave thereafter. Due to the stepped circumference of the second sheave the four ropes for suspending the counterweight have a slightly larger mutual distance than the four ropes for suspending the car. Furthermore, elevators are known comprising a sheave arrangement of four sheaves. One pair of sheaves having aligned axes pays out the ropes for suspending the car, and another pair of sheaves having aligned axes pays out the ropes for suspending the counterweight. The elevator may be equipped with a linear motor drive. The sheaves of each of the sheave pairs have a large mutual distance, for example, approximately one half of the width of the car, so that they are attached to the car at a substantial distance from the vertical line passing through the center of gravity of the car. Since it may occur that the ropes are paid out at slightly different speeds or lengthen differently, extra moments may be exerted to the car. This leads to oscillations to the moving car and uncomfortable feelings of the passengers; the guide rollers provided on both sides of the car may be damaged. It is an object of the invention to provide an elevator having a uniform ascending and descending movement of the car. According to the invention, the elevator is characterized in that d) said sheave arrangement, when viewed in plan, comprises a first sheave and a second sheave, forming a V-type arrangement with the axes of rotation of the two sheaves being angular to each other; e) and a first number of said ropes is guided by said first sheave and a remaining, second number of said ropes is guided by said second sheave. Preferably, the sheave arrangement comprises four sheaves forming said V-type arrangement when viewed in plan. Preferably, the elevator is provided with a linear motor drive, comprising a primary conductor arranged at the counterweight and a vertical column as a secondary conductor. The elevator of the invention can be built with reduced installation space for the sheaves. The sheave arrangement may be disposed in the upper section of a building. An embodiment of the invention will be described in the following with reference to the drawings. Fig. 1 ist a schematic perspective view illustrating an elevator using a linear motor (this elevator does not include a sheave arrangement in accordance with the invention); Fig. 2 is a schematic perspective view illustrating a sheave arrangement of an elevator in accordance with the invention; Fig. 3 is a top plan view illustrating the sheave arrangement shown in Fig. 2 . Referring to Fig. 1, an elevator car 1 is fixed to one end of ropes 3 by means of rope fixing ends 2. The other ends of the ropes 3 are fixed to rope fixing ends 7 which are secured to the upper end of a counterweight 6. The ropes 3 are supported by first and second sheaves 4, 5 which are rotatably supported in the upper section of a building. The first sheave 4 and the second sheave 5 are supported by a sheave shaft support member 9 by means of sheave shafts 8 in an elevator machine room. The car 1 has car guide rollers 11 provided on both sides thereof and engaged with car guide rails 10. The counterweight 6 has counterweight guide rollers 13 engaged with counterweight guide rails 12. The counterweight 6 is arranged such that it performs rectilinear motion in the vertical direction along a column 8 corresponding to the secondary conductor of a linear induction motor. The column 8 is supported at both ends by an upper end support section 15 secured to a ceiling beam 14 and a lower end support section 17 secured to a floor frame 16. Reference numeral 19 denotes the primary conductor of the linear motor. The linear induction motor shown in this embodiment is of such a type that the secondary conductor is held in the installation position, and the primary conductor 19 alone performs rectilinear motion. In Fig. 1, the stator 19 is positioned in the center part of the counterweight 6 in consideration of the balance of the counterweight 6. The conventional sheaves have a parallel arrangement having a relatively wide distance, as mentioned above. Fig. 2 shows a V-type sheave arrangement. The ropes 3 paid out from the sheaves placed in the machine room in the upper section of the building, pass through an opening 20 in the machine room and are fixed to the rope fixing ends 2 on the car 1. As clearly shown in Fig. 2, a plurality of rope fixing ends 2 fixing a plurality of ropes are concentrated in the vicinity of the vertical line passing through the center of gravity of the car. Fig. 3 is a plan view illustrating the sheaves arranged in a V-shape as shown in Fig. 2 . With this V-shape arrangement, a plurality of car side ropes can be brought to be close together. For example, in the case of the sheaves in the V-type array arrangement in the present embodiment, the minimum space distance L between the centers of the adjacent sheaves as shown Fig. 3 is set to be 100 mm, whereas the maximum space distance between the centers of the counterweight side sheaves is set to 650 mm. From these numerical values it is understandable that the sheave arrangement according to the present invention effectively allows a plurality of ropes to approach the vertical line passing through the center of gravity of the car 1. The invention results in the following advantages: Since a plurality of ropes are fixed to the elevator car, being converged in the vicinity of the vertical line passing through the center of gravity of the car, a constant attitude of movement of the car can be maintained. Accordingly, no extra moments are produced relative to the center of gravity of the car, whereby it is possible to provide an elevator which causes extremely slight oscillation and which is very comfortable. Furthermore, it is possible to save the installation space of the sheave section arranged in the machine room of the elevator.

Claims: An elevator comprising: a) a car (1) and a counterweight (6) suspended by ropes (3); b) and a sheave arrangement guiding said ropes (3); c) with the ropes (3) as paid out from a first sheave arrangement section for suspending said car (1) being at a smaller maximum horizontal distance than the ropes (3) as paid out from an opposite second sheave arrangement section for suspending said counterweight (6) and being attached to said car (1) in the vicinity of a vertical line passing through the center of gravity of said car (1), characterized in that d) said sheave arrangement, when viewed in plan, comprises a first sheave (4) and a second sheave (4), forming a V-type arrangement with the axes of rotation of the two sheaves (4,4) being angular to each other; e) and a first number of said ropes (3) is guided by said first sheave (4) and a remaining, second number of said ropes (3) is guided by said second sheave (4). The elevator of claim 1 wherein said sheave arrangement comprises four sheaves (4,4,5,5) forming said V-type arrangement when viewed in plan. The elevator of claim 1 or 2 wherein a linear motor drive is provided, comprising a primary conductor (19) arranged at the counterweight (6) and a vertical column (8) as a secondary conductor.

Inventors: NAKAI KEIICHIRO, NAKANISHI YOSHINORI, NAKAI, KEIICHIRO, NAKANISHI, YOSHINORI
Applicants: OTIS ELEVATOR CO, OTIS ELEVATOR COMPANY
Application year: 1989
Main classification: B66B11
IPC codes: B66B7, B66B11