GB2187429A - A chain tensioning device for driving the steps of a passenger conveyor - Google Patents

Abstract

The present invention provides device tensioning the chains for driving the steps of a passenger conveyor which is provided with wheels (8) provided with rubber-based elastic bodies (8) on the peripheral surfaces thereof having a smaller width than the inner width of the link plates (17) of the step-driving chains (4) so that the chain rollers (18) of the step-driving chains (4) are received by the rubber-based elastic bodies (9), whereby a shock absorbing effect can be obtained by a simple configuration. <IMAGE>

Description

SPECIFICATION A chain tensioning device for driving the steps of a passenger conveyor The present invention relates to a chain-tensioning device for driving the steps of a passengerconvevor, and particularly to a chain-tensioning device which drives the steps of a passenger conveyor, being provided with a shock absorber for the chain.

British Patent No. 719694 discloses a chain-tensioning device for driving the steps of a passenger conveyor which has as its object to absorb the shock generated when a chain engages with a sprocket wheel.

The device disclosed in the above British Patent is provided with elastic bodies on both sides of the sprocket wheel and the link plates ofthe chain are received bythe elastic bodies so that the shock generated when the chain engages with the base of the teeth ofthesprocketwheel is moderated.

The link plates of the chain are generally formed by punching copper plate by a press. Thus, in the configuration disclosed in the above-described British Patent, edges (thickness portions) ofthe link plates are repeatedly pressed into the elastic bodies.

Consequently, the elastic bodies become extremely worn and the lifetime thereof is shortened, so that the shock absorbing effect disappears in a short period oftime.

Furthermore, in the configuration disclosed in the above British Patent, it is a premise that the teeth of the sprocket wheel are formed by machining. The formationoftheteeth ofthesprocketwheel andthe execution of the elastic bodies make the production of a sprocket wheel having this shock absorbing effect complicated and difficult.

It is an object ofthe present invention to provide a chain-tensioning device which drives the steps of a passenger conveyor, being able to obtain a shock absorbing effectdueto a simple configuration.

Another object of the present invention is to provide a chain-tensioning device which drives the steps of a passenger conveyor, being able to maintain its shock absorbing effect for a long period oftime.

The above-mentioned objects are achieved buy a chain-tensioning device for driving steps in which a disc its used and an annular elastic body that projects slightly from the external diameter of the disc is mounted on the outer periphery of the disk so that a chain roller is received by the elastic body. That is to say, each chain roller of a chain would around the disc is received by the elastic body provided on the outer periphery of the disk. Therefore, no shock is generated beween metals such as the chain rollers and the teeth of the sprocket wheel, and unpleasant noises and vibration can be prevented.In addition, since the elastic body receives each chain roller, the degree of wears is small, compared with the case in which elastic bodies receive the edges of the plates, sothattheshockabsorbing effectcan bethus maintained over a longer period of time than in conventional devices.

The present invention will now be described in greater detail by by of example with reference to the accompanying drawing wherein Figure 1 is a schematisviewofthewhole of a passenger conveyor; Figure2 is an enlarged view of an embodimentof the chain-tensioning device for driving the steps of a passenger conveyor; and Figure 3 is an enlarged sectional view taken along thelineA-Ain Figure 2.

An embodiment ofthe present invention will be described belowwith reference to Figures 1 to 3.

A passenger conveyor generally comprises a frame 1 which supports the dead weightthereofand a passenger load; a pair of right and left balustrades 2 which are erected on either side of the frame 1 in the longitudinal direction thereof, and which are provided with moving hand-rails on the peripheries thereof; a plurality of steps 3 which are placed between the two balustrades 2, driven in synchronism with the moving hand-rails, and connectedtogetherin an endless loop; a pair of right and left step-driving chains 4which are individual connected to an under portion of a plurality ofthe endlessly-connected steps 3 and which are disposed in the longitudinal direction of the frame Ia a pair of right and left driving sprocket wheels 5 which are placed in the interior oftheframe 1 at the upper end thereof and around which the corresponding step-driving chains 4 are wound; a step-driving chain tensioning device 6 which is provided in the interior of the frame 1 at the lower end thereof and around which the step-driving chains 4 are wound so asto provide a constant tension; and a driving apparatus 7 which is provided in the interior of the frame 1 at the upper end thereof and which imparts a driving force to the driving sprocket wheels 5.

The step-driving chain-tensioning device 6 comprises a pair of two wheels 8 made of discs, elastic bodies 9 made of a rubber-based material, such as polyurethane rubber, which are wound around the peripheries of the wheels; a shaft 10for supporting the two wheels 8; bearings 11 for rotatably supporting each end of the shaft 10; bearing boxes 12 for covering the bearings 11; guide rails 13 which are laid on a fixed member along the direction of the movement of the steps and which slidablyguidethebearingboxesl2; rods 14 connected to the bearing boxes 12; engagement fittings 15 through which the other ends of the rods 14 pass and which are fixed to fixed members; and springs 16 which are placed between the engagement fittings 15 and the ends of the rods 14 and which apply a constant force to the step-driving chains 4.

The elastic bodies 9 are wound around the wheels 8 bythefollowing method. Firstly, each wheel 8 isso formed that the width W of its periphery is smaller than the innerwidth (Wc) between link plates 17 of the step-driving chains 4 and is substantially equal to the equivalent dimension of chain rollers 18. A concave groove 19 isformed around the entire peripheral surface 8S of each wheel 8formed in this manner, and the elastic body 9 having a rectangular section is fitted into the concave groove 19. A peripheral surface 95 of the elastic body 9 is allowed to projectfrom the concave groove 19so that the chain rollers 18 are elastically supported by the projecting portion ofthe peripheral surface (9S).At the same time, the peripheral surface of the wheel 8 is placed between the link plates 17 and is inserted as far as the side of the chain roller 18so thatthe wheel (8) and the link plate (17) form an overlapping portion L. In addition, the diameter D ofthe elastic body 9 on each wheel 8 is set so that no integral multiple of the chain pitch angle of the step-driving chains 4wound therearound is 360 degrees.

The elastic bodies 9 may be mounted onto the peripheral surface8S ofthewheels 8 byfixingthem in the concave grooves 19 by means of adhesive or molding, or each elastic body may be formed into a ring and fitted into its groove by employing the elasticity ofthe elastic body 9. In addition, without-forming concave grooves 19 on the wheels 8, the elastic bodies may be fixed onto the peripheral su rfaces 8S by one ofthe above-described means.

In the above-mentioned configuration, when the passenger conveyor is driven, the step-driving chains 4 are driven by the driving sprocket wheels and are endlessly moved between the sprocket wheels and the chain-tensioning device 6 so as to move the steps 3. The step-driving chains 4 are guided on the peripheries of the wheels 8 by the overlapping portions L between the link plates 17 and side surfaces 20 on the peripheries of the wheels 8 sothatthey arewound around thewheels 8 without separating therefrom. In addition, the wheels 8 are tensioned by the springs 6 through the rods 14 and apply a constant tension to the step-driving chains 4 so as to smoothly rotate them.

When the step-driving chains 4 are wound around the wheels 8, the chain rollers 18 are received by the elastic bodies 9 so thatthe shock is absorbed, whereby it is possible to prevent the generation of unpleasant noises and vibration. In addition, the relationship betwee the chain pitch angle ofthe step-driving chains 4 and the diameter D ofthe elastic bodies 9 allows the contact positions between the chain rollers 18 and the elastic bodies 9 to be constantly changed so that the chain rollers are successively brought into contact with a series of succeeding positions. Therefore, there is sufficient time between the moment when the chain rollers 18 separate from the elastic bodies 9 and the moment when they are again broguth into contact with their original positions.This means that there is a large reduction infrequency at which the chain rollers 18 are supported, in comparison with a device in which the chain rollers 18 are repeatedly supported at particular positions on the elastic bodies 9 and thus enables the lifetime of the elastic bodies 9 to be prolonged. However, a configuration in which the chain rollers 18 are solely brought into contact with the elastic bodies 9 may decrease the amount of wear of the elastic bodies 9 and prolong the lifetime in comparison with the configuration in which the edges ofthe link plates are brougth into contact with the elastic bodies 9.

Furthermore, the maintenance and inspection of the wheels 8 may be mainly made with emphasis on the elastic bodies 9 because the step driving chains (4) are mainly brouht into contact with the elastic bodies 9 and it is thus sufficient to replace worn elastic bodies (9) alone. Therefore, the total maintenance cost of the passenger conveyor is lowered.

As described above, the ernbodimentofthe present invention can be put into practice by omitting the portion which has conventionally comprised a sprocket wheel and has required an expensive gear cutting operation and replacing it with a portion having a simple configuration in which the elastic bodies are provided on the peripheries of the simple disk wheels, and yetwhich adequatelyfunctions as the tensioning device 6 for the step driving chains 4.

The present invention provides a step-driving chain tensioning device of a passenger conveyor which enables a simple configuration and effects the shock absorbing function required.

Claims (4)

1. A chain tensioning device for driving the steps of a passenger conveyor provided with a plurality of steps endlessly connected; step driving chains for driving said steps; driving sprockets drive said chains with said step driving chains wound around said driving sprockets; and a tensioning device for providing tension to said step-driving chains, said tensioning device being characterized by comprising disc wheels provided with rubber-based elastic bodies on the peripheral surfaces thereof which have a width smallerthan the inner width of the link plates of said step-driving chains so that the chain rollers of said step-driving chains are received by said rubber-based elastic bodies.

2. A chain tensioning device for driving the steps of a passenger conveyor according to claim 1, wherein the diameter of said elastic bodies is so set that no integral multiple ofthe chain pitch anglewill be equal to 360 degrees.

3. A chain tensioning device for driving the steps of a passenger conveyor according to claim 1, wherein the peripheries of said wheels have portions overlapping said link plates of said step-driving chains.

4. A chain tensioning device for driving the steps of a passenger conveyor constructed substantially as herein described with reference to the accompanying drawing.