Background Art

The majority of existing designs of elevators for transportation of loads and/or persons comprise a traction machine, an elevator car suspended on a traction and load bearing means such as roping, and a counterweight positioned on the opposite end of the traction and load bearing means. The traction and load bearing means is led over a traction sheave connected to the traction machine. The counterweight balances the weight of the elevator car and during its upward movement leads to a lower power consumption of the traction machine. The disadvantage of this solution is that the counterweight moves in the hoistway and decreases the space available inside the hoistway. Also, it causes an increased energy consumption.

Several vertical hoist systems without the need for counterweight are known. The common technical problem to be solved is the maintenance of sufficient traction of the traction and load bearing means in order to achieve the desired movement and position of the elevator car. In the documents US 2006/0225965, WO 2004/094289, WO 2004/094287 and others, a system of deflection sheaves attached to the top and bottom of the hoistway and to the elevator car and a more or less complex external tensioning device acting directly on the traction and load bearing means are used to maintain the sufficient traction. WO 2005/049470 uses a system of deflection sheaves and parallel ropes.

In WO 2010/059167 a system of deflection sheaves and a lever-weight assembly is used for maintaining the sufficient traction. One end of the traction and load bearing means is attached to a lever and the tension is maintained by means of a traction weight mounted on a spring.

The aim of the present invention is, therefore, the development of a simple design of a vertical hoist system for transportation of persons and/or loads, which will not require the counterweight and will consequently enable utilization of the entire space inside the hoistway resulting in larger dimensions of the elevator car and a higher maximum load of the elevators. The novel vertical hoist system is reliable and automatically adjusts the force used to maintain the sufficient traction to the actual weight of the elevator car. This enables an optimum use of energy, since the energy is consumed only on the hoisting of persons and/or load and no energy has to be used for hoisting any counterweight.

Disclosure of the Invention

The object of the present invention is a vertical hoist system comprising a lever, an elevator car attached to the lever through an attachment means, a traction and load bearing means having a first end and a second end, an upper sheave assembly and a lower sheave assembly, and a traction machine,

wherein the first end of the traction and load bearing means is attached to the lever, the traction and load bearing means is led over the upper sheave assembly and over the lower sheave assembly and attached to the lever through its second end, wherein the point of attachment of the first end of the traction and load bearing means is located on the lever between the point of attachment of the elevator car and the point of attachment of the second end of the traction and load bearing means.

From the first end, the traction and load bearing means leads upwards towards the upper sheave assembly, and from the second end, the traction and load bearing means leads downwards towards the lower sheave assembly.

In the present vertical hoist system, the suspension of the elevator car on the lever creates a sufficient tension in the traction and load bearing means and a sufficient traction on both sheave assemblies. Consequently, no counterweight is required in order to balance the weight of the elevator car. Due to the fact that the elevator car itself creates the tension, the tension corresponds to its momentary weight.

The vertical hoist system of the present invention includes any system for hoisting persons and/or loads, such as an elevator, a lift, a lifting platform, a lifting system etc. Consequently, the term "elevator car" includes any suitable transportation container or platform.

The upper sheave assembly comprises one or a plurality of sheaves. The lower sheave assembly comprises one or a plurality of sheaves.

The upper sheave assembly is located in the upper part of the hoistway or above the hoistway. The lower sheave assembly is located in the lower part of the hoistway or next to the hoistway. One sheave assembly (the upper sheave assembly or the lower sheave assembly) is a traction sheave assembly and the other sheave assembly (the lower sheave assembly or the upper sheave assembly) acts as a diverting pulley assembly. The power for the traction sheave assembly is provided by the traction machine, which is usually located close to the traction sheave assembly. In a preferred embodiment, the traction sheave assembly together with the traction machine are located in the upper part of the hoistway or above the hoistway and the diverting pulley assembly is located in the lower part of the hoistway. In another preferred embodiment, the traction machine and the traction sheave assembly are located in the lower part of the hoistway and the diverting pulley assembly is located in the upper part or above the hoistway.

Preferably, the traction machine is equipped with a frequency convertor. This embodiment results in an accurate levelling of the elevator and elimination of the vibrations. This in turn prolongs the traction machine lifespan and leads to an improvement of travel comfort during start and stopping of the elevator.

The traction and load bearing means can be any means used in the field of elevators for transmission of traction and for bearing (raising and lowering) the elevator car. Most commonly used traction and load bearing means is, e.g., roping or cabelling, including one or a plurality of ropes, flat cables or flat belts. The ropes can be, e.g., traction steel ropes.

Attachment of the first end and the second end of the traction and load bearing means on the lever can be achieved by any means known to a person skilled in the art, such as screws, hinged screws or swiveling suspensions. It is preferably achieved through a right-hand swiveling suspension and a left-hand swiveling suspension.

The attachment means for attaching the elevator car to the lever is preferably a swiveling suspension. This enables free load balancing and a more fluent elevator travel, particularly levelling.

The present invention provides a vertical hoist system which has a simple design and is cost-effective in terms of production materials and installation, as well as energy consumption during its day to day operation. In contrast to other known vertical hoist systems the power consumption is proportional to the weight of transported persons and/or load.

Brief Description of Drawings

Fig. 1 shows a schematic representation of one embodiment of the vertical hoist system according to the invention.

Example of Carrying Out of the Invention

The present invention is herein illustrated by way of example which should not be construed as further limiting.

Fig. 1 shows a schematic representation of the vertical hoist system according to the invention, more particularly an elevator system. The vertical hoist system comprises a lever 4, an elevator car 3 attached to the lever 4 through an attachment means 6, a traction and load bearing means 8 having a first end 5 and a second end 7, an upper sheave 1 and a lower sheave 2, and a traction machine (not depicted). The first end 5 of the traction and load bearing means 8 is attached to the lever 4, the traction and load bearing means 8 is led first over the upper sheave I and then over the lower sheave 2 and then is attached to the lever 4 through its second end 7. The point of attachment of the first end 5 of the traction and load bearing means 8 is located on the lever 4 between the point of attachment 6 of the elevator car 3 and the point of attachment of the second end 7 of the traction and load bearing means 8. This construction results in the elevator car 3 creating a sufficient tension in the traction and load bearing means 8 and a sufficient traction on both sheaves 1 and 2. The end of the lever 4 on which the elevator car 3 is suspended is pulled downwards by the weight of the elevator car 3, thereby the other end of the lever 4 is pushed upwards, which results in the increase of the tension in the traction and load bearing means 8.

In this example the upper sheave I acts as a traction sheave and the lower sheave 2 acts as a diverting pulley. The elevator car 3 travels vertically in the hoistway and this vertical movement is linked to the movement of the traction and load bearing means 8 powered by the traction sheave 1 connected to the traction machine (not depicted). The tension in the traction and load bearing means 8 is achieved through the momentary weight of the elevator car 3 suspended on the lever 4 _^ which creates tension in the traction and load bearing means 8 and the traction of traction sheave 1. The traction machine can be equipped with a frequency converter and together with the traction sheave I is located in the upper part of the hoistway. This embodiment results in an accurate levelling of the elevator car 3 and the elimination of the vibrations. This in turn prolongs the traction machine lifespan and leads to the improvement of travel comfort during start and stopping of the elevator car 3.