US 3768596 A
Resilient spacers provided for alternate links of an elevator compensation chain maintain the links fully extended thereby eliminating chain rattle. The cross-sectional dimensions of the spacers exceed those of the chain links to eliminate noise which would result from the links striking components in the hoistway. Y type connections to the car and counterweight permit the use of a single compensation chain without interference with the buffers.
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Description (OCR text may contain errors)
I United States Patent 1 [111 3,768,596 Solymos Oct. 30, 1973  ELEVATOR COMPENSATION CHAINS 413,123 10/1889 Arthur 187/94 847,228 3/1907 Bixby 1 59/78  lnventor: Frederick Solymos,Glenridge,N.J. 1,2669% 5,1918 Shade 59/78  Assignee: Westinghouse Electric Corporation, 2920943 11/1935 Hanpuisu 59/78 Pittsbur h Pa 2,178,041 10/1939 Hodell 152/239 g 2,973,223 2/1961 Whatley 59/78  Filed: Mar. 31, 1972 Primary Examiner-J-larvey C Hornsby  Appl' 240341 Att0rneyA. T. Stratton et a1.
Related U.S. Application Data  Continuation of Ser. No. 18,187, March 10, 1970,  ABSTRACT abandoned Resilient spacers provided for alternate links of an ele vator compensation chain maintain the links fully ex-  U.S. Cl 187/21, 187/67, 187/94, tended thereby eliminating chain ram, The Cross 59/78 59/80 254/178 sectional dimensions of the spacers exceed those of ll'lt. chain links to eliminate noise would result  F'eld Search l87/20 67; from the links striking components in the hoistway, Y 59/78 82; 254/135 178; 293/72; type connections to the car and counterweight permit 152/231 239 the use of a single compensation chain without interference with the buffers.  References Cited v UNITED STATES PATENTS 4 Claims, 5 Drawing Figures 10,017 1/1882 Baldwin 187/94 4TH LANDING 3RD LANDING ELEVATOR COMPENSATION CHAINS CROSS-REFERENCE TO RELATED APPLICATION This application is a continuation of application SER. No. 18,187 filed Mar. 10, 1970, which is assigned to the same assignee as the present application.
BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to elevator systems and more particularly to compensation chains utilized in elevator systems in which the elevator car is suspended from a cable and is counterbalanced by a weight attached to the other end of the cable.
2. The Prior Art In the widely used traction drive forelevators, the elevator car is counterbalanced by a weight connected to the opposite end of the cable supporting the car. The cable passes over a drive sheave having a V-shaped groove in its periphery. The weight of the car and the counterweight supply the traction force which permits the car to be raised and lowered by rotation of the drive sheave. Generally, the counterweight is made equal to the weight of the car plus 40 percent of the load capacity of the car. In this manner, the torque applied to the drive sheave only need be sufficient to overcome the difference between the weight of the counterweight and the car plus its load.
Of course, the supporting cable also contributes to the suspended load of the system. The effect of the weight of the cable varies, however, since when the car is at the lower limit of travel, the weight of almost the entire length of the cable is added to the weight of the car. On the other hand, the weight of the cable appears almost entirely on the counterweight side of the drive sheave when the car is at the upper limit of travel. For low rise elevator installations the resulting continuous shift in the suspended load can be ignored; however, for high rise, high speed installations the continuously changing torque requirements are not insignificant.
One approach to the problem has been to attach a cable to the bottom of the car and the bottom of the counterweight. The shift in the suspended load on either side of the drive sheave as the car moves up and down in the hoistway caused by this hanging cable is opposite to, and tends to cancel out, the shift in load caused by the supporting cable. Generally, a pulley arrangement is provided at the bottom of the hoistway to prevent the hanging cable from lashing about. In the heavier duty elevators where several supporting cables are utilized, several compensation cables must be utilized to balance the loading. This necessitates the additional pulley arrangements at the bottom of the hoistway which inherently adds to the cost of the system.
A less expensive approach to the. problem has been to suspend a chain between the bottom of the car and the bottom of the counterweight. Chains of a wide variety of weights are available, thus it is not necessary to have several chains as in the case of cables. In addition, a pulley arrangement at the bottom of the hoistway is not required. One drawback of the compensation chain, however, is the noise developed as the links pass through the bottom of the loop. This noise problem has heretofore limited the utilization of compensation chains to the lower speed installations. An attempt has been made to minimize the noise by threadinga rope through the links of the chain, but this has not been entirely satisfactory in eliminating noise and the rope must be replaced periodically due to wear.
Elevator codes require that a buffer be provided which is capable of bringing th car to a safe stop should it overtravel in the downward direction. It has been the practice to utilize two small compensation chains distributed on either side of the center of gravity of the car so that there is no interference with the buffer.
SUMMARY OF THE INVENTION According to this invention, resilient spacers are provided for a plurality of alternate links of an elevator compensation chain. The spacers bear against the adjacent links to maintain the chain fully extended yet flexible thereby eliminating chain rattle as the elevator car moves up and down in the hoistway. This permits the use of compensation chains on higher speed installations in place of the more expensive cables and compensators. In addition, the invention provides improved noise suppression and wear characteristics over prior art devices. An additional feature of the invention is that the dimensions of the spacers transverse to the axis of the chain exceed the corresponding dimensions of the links of the chain so that the links will not contact the walls or other components in the hoistway.
In a preferred embodiment of the invention, the resilient spacers are in the form of elongated sleeves which are fitted over alternate links of the chain. The sleeves are of such a length that they force the adjacent links to be fully extended so that they cannot rattle. Since the sleeves are made of resilient material, the chain is still able to bend as the links traverse the bottom of the loop formed by the hanging chain. The diameter of the generally cylindrical sleeves exceeds the width of the links so that the adjacent links cannot strike the hoistway or other components therein and generate additional noise.
In the interests of economy, it is desirable to minimize the number of spacers required by utilizing one heavy compensation chain rather than two lighter weight chains as is the usual practice. In order to avoid interference with the car and counterweight buffers, Y type connections are provided on both ends of the chain. The length of the loop of the compensation chain must beadjusted so that the single chain does not strike the buffers when the car is at intermediate floors.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic isometric view of an elevator installation embodying an exemplary form of the invention.
FIG. 2 is an isometric view of a portion of an elevator compensation chain incorporating an exemplary em- 'bodiment of .the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT Referring .to FIG. 1, an elevator car 1 is suspended in a hoistway 3 by a cable 5 A counterweight 7 is connected to the other end of the cable which is reeved over a drive sheave 9. The drive sheave is rotated by a motor 11 through a drive shaft 13. Energization of the motor causes the car to travel up and down in the hoistway to serve a plurality of landings four of which are illustrated in FIG. 1. A single compensation chain 15 is connected to the bottom of the car 1 and the counterweight 7 with the intermediate links hanging freely in the hoistway.
As the car, and hence the counterweight, move up and down in the hoistway, the amount of compensation chain exerting a force on one side of the traction sheave or the other varies inversely in proportion to the amount of cable exerting force on the same side of the traction sheave. For example, as shown in FIG. 1, when the car is at the third floor, where a substantial amount of the cable is on the counterweight side of the traction sheave, a small portion of the compensation chain is exerting a force on that side of traction sheave. As the car moves downward in the hoistway, less cable exerts a force on the counterweight side of the traction sheave, but a proportionally larger portion of the compensation chain is supported through the counter weight. In this well known manner the loading on the traction sheave remains substantially constant as the car moves through the hoistway.
In order to eliminate the rattling of the chain as the car moves through the hoistway, spacers 17, constructed of any resilient material such as rubber, are provided for alternate links (see FIGS. 2 and 3). The spacers illustrated are in the form of elongated sleeves which are slipped over the end of the chain and positioned so as to encompass the selected links 19a. The dimension a of the spacers is such that the end surfaces of the sleeves urge the adjacent links 19b into full extension with respect to the links 19a. Since the sleeves are made of resilient material, the chain remains flexible but the links are kept in constant contact with each other so that they cannot rattle.
It can be seen from FIG. 3 that the diameter b of the cylindrical sleeves exceeds the width of the links. This prevents the adjacent links 19b from striking the walls of the hoistway and greatly reduces the likelihood of their coming into contact with other components in the hoistway thereby further reducing chain noise.
Elevator codesjrequire that buffers be provided to absorb the shock should the car or'the counterweight overtravel in the downward direction. Such buffers are well known in the elevator art. Since the buffers are aligned to act through the center of gravity of the car and the counterweight, it has been the usual practice to install the compensation chain in two lengths with the corresponding ends of each length attached to the car and the opposite ends attached to the counterweight at points equidistant from the respective centers of gravity and on a line passing through the centers of gravity. In this manner, the compensation chain does not interfere with the buffers.
Since according to the present invention it is contemplated that spacers be provided for every other link in the compensation chain, it is desirable to utilize a single heavier length of chain in order to minimize the number of spacers required. In order to meet the requirements that the forces exerted by the compensation chain act through the center of gravity of the car and the counterweight and that the chain not interfere with the buffers, two flexible connectors attached to each end of the chain form a Y type connection with the chain. The connectors, a and 15b, attached to the end of the chain 15 to be connected to the car are fastened to the bottom of the car at points equidistant from the center of gravity of the car and on a line pass ing through the center of gravity. The flexible connectors for the other end'of the compensation chain are similarly fastened to the bottom of the counterweight. Chains can be utilized as the connectors.
Since the car approaches within a few inches of the buffer at its normal lower limit of travel, the length of the chain must be properly selected. The chain must be long enough to permit the car to reach its normal lower limit. However, since the chain will assume a position under the center of gravity of the car it must not be so long that it strikes the buffer. As shown in FIG. 4, the bottom of the loop is slightly above the top of the buffer 21 when the car is at intermediate floors. As the car approaches the normal lower limit of travel as shown in FIG. 5, the flexible connectors 15a and 15b, provide clearance between the chain and the buffer. Similar flexible connectors attaching the chain to the counterweight provide clearance between the chain and the buffer. Similar flexible connectors attaching the chain to the counterweight provide clearance between the chain and the buffer 23 when the car reaches its upper limit of travel. Actually, the chain could be long enough so that the bottom of the loop is below the top of the buffers due to the curvature of the loop. Ordi narily, the chain would have a tendency to lash about as the car was in motion, however, the spacers serve to reduce this tendency.
In summary, resilient spacers which maintain an elevator compensation chain fully extended and which protrude laterally beyond the links thereby reducing chain rattle and noise caused by the chain striking objects in the hoistway have been disclosed. Although elongated sleeves which are slipped over alternate links have been specifically disclosed, spacers in other forms which function in a similar fashion are fully within the scope of the invention. The spacers can be utilized on a single compensation chain which is connected to the car and counterweight by Y type connections which eliminate interference with the buffers.
I claim as my invention;
1. An elevator system comprising a structure having a hoistway with a plurality of vertically displaced landings, an elevator car, a counterweight, a cable connected at one end to the car and at the other end to the counterweight, a traction sheave mounted at the top of the hoistway, said cable being reeved over the traction sheave with the elevator car and the counterweight being suspended in the hoistway, motive means connected to the traction sheave for raising and lowering the elevator car in the hoistway to serve the landings, a compensation chain having a series of interconnected links being connected at one end to the elevator car and at the other end to the counterweight with the intermediate links hanging in a loop beneath the car and the counterweight and the improvement which comprises a plurality of tubular resilient spacer members disposed about a plurality of alternate links of said compensation chain and dimensioned such that the ends of each tubular member bear against the adjacent links which are free of such spacer members, whereby the chain is fully extended yet flexible and therefore does not make an appreciable noise as the car moves up and down in the hoistway.
2. The combination of claim 1 wherein the dimensions of the spacer member transverse to the axis of the chain exceed the corresponding dimensions of the links of the chain, whereby the links of the chain will not contact the walls or other components in the hoistway, thereby further reducing the noise level.
3. The combination of claim 1 including a buffer located at the bottom of the hoistway aligned with the center of gravity of the car and operative to bring the car to a safe'stop should the car overtravel in the downward direction and also including two lengths of flexible connector for connecting the chain to the car, one end of each flexible connector being attached to the end of the chain and the other end of each flexible connector being separately attached to points equidistant from the center of gravity of the car on a line passing through said center of gravity, with the chain being of such a length that the loop formed by the hanging chain does not strike the buffer when the car is above its lower limit of travel, whereby the chain and flexible connectors will not contact the buffer at any point of travel of the car even as it overtravels in the downward direction.
4. The combination of claim 3 including a buffer for said counterweight and a second pair of flexible connectors for connecting the chain to the counterweight, one end of each flexible connector being connected to the end of the chain and the other end of each flexible connector being separately attached to points equidistant from the center of gravity of the counterweight on a line passing through said center of gravity.