Abstract:
A method of controlling noise noticeable within an elevator car ( 22 ) includes intentionally introducing noise into the elevator car ( 22 ) at a noise level that depends on the position of the car within a hoistway ( 24 ). A disclosed example includes using existing elevator system components for generating compensating noise at different levels corresponding to different positions of the car within the hoistway. One disclosed example includes increasing introduced noise as the car descends further away from a machine responsible for moving the car. The introduced noise reduces or eliminates changes in noticeable noise within the elevator car as the car moves relative to the machine. The disclosed examples have particular usefulness in machine roomless elevator systems although they are not necessarily limited to such systems.

Description:
FIELD OF THE INVENTION 
     This invention generally relates to elevator systems. More particularly, this invention relates to sound quality and noise control for elevator systems. 
     DESCRIPTION OF THE RELATED ART 
     Elevator systems come in a variety of forms. Many utilize a machine to move roping such as steel ropes or flat belts to cause desired movement of an elevator car between various levels of a building, for example. Traditionally, the elevator machine was located in a machine room above the hoistway within which the elevator car travels. More recently, machine roomless elevator systems have been introduced. While such systems have advantages in that they utilize less building space, for example, they are not without drawbacks. 
     For example, the location of the machine within the hoistway introduces another source of noise that is noticeable within some elevator car configurations. One aspect of this noise is that it tends to increase in loudness and becomes more noticeable as the elevator car approaches the machine, typically near the upper floors of the building. The noticeable change in noise within the elevator car as the car moves relative to the machine is considered undesirable. Passengers may be accustomed to a relatively constant level or slowly changing gradient in noise while riding in an elevator but typically are disturbed by rapidly changing levels of noise as the car is moving. 
     There is a need for an arrangement that reduces or eliminates the change in noticeable noise within an elevator car as it travels within a hoistway, for example. This invention addresses that need. 
     SUMMARY OF THE INVENTION 
     An exemplary disclosed method of controlling a noise level within an elevator car includes introducing noise into the elevator car in an amount that is dependent upon the location of the elevator car. 
     One disclosed example includes introducing noise into the elevator car such that it results in a generally consistent noise level in the elevator car along an entire distance traveled by the elevator car. 
     One example includes increasing the amount of introduced noise as the elevator car moves farther from the machine used to move the elevator car. In one example, increasing the amount of introduced noise occurs as the elevator car descends. 
     One example includes using at least one component associated with moving the elevator car other than the machine for introducing the noise. One example includes altering a surface on a guide rail such that interaction between at least one other component associated with the elevator car and the guide rail surface results in the introduced noise. One example includes different surface characteristics along different portions of the guide rail surface to introduce different levels of noise. 
     One example includes using roping or belts with varying characteristics for introducing the noise. In this case the varying level of noise is introduced by the varying levels of structural-acoustic interaction between the roping and the pulleys on the car frame. 
     An exemplary disclosed elevator system includes an elevator car and a machine for moving the elevator car. At least one other component introduces noise into the elevator car in an amount that depends on a distance between the elevator car and the machine. 
     The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  schematically illustrates selected portions of an elevator system designed according to an embodiment of this invention. 
         FIG. 2  is a graphical illustration summarizing one example approach designed according to an embodiment of this invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  schematically shows selected portions of an elevator system  20 . An elevator car  22  travels within a hoistway  24  responsive to operation of a machine  26 . 
     In the illustrated example, the machine  26  causes a drive or traction sheave  30  to rotate to move a load bearing member  32  such as a steel rope or flat belt to cause desired movement of the car  22  within the hoistway  24 . The illustration schematically shows a guide rail  34  that the elevator car  22  follows as it moves vertically within the hoistway  24 . Guidance components  36  operate in a known manner to facilitate movement of the car  22  along the guide rail  34 . 
     In this example, the elevator system  20  is a machine roomless system such that the machine  26  is supported within the hoistway  24  in a known manner. The presence of the machine  26  within the hoistway  24  introduces noise that can be noticed within the elevator car  22  especially when the elevator car  22  is close to the machine  26 . For example, as the elevator car is closer to the machine  26 , the machine noise is more noticeable. Such noise levels within the elevator car  22  are lower as the elevator car  22  descends or moves away from the machine. Because the machine  26  introduces noise in the hoistway  24  that can be noticed in the elevator car  22 , the disclosed example includes a strategy for minimizing time rate of change in the amount of noticeable noise within the elevator car  22  regardless of the position of the elevator car  22  in the hoistway  24 . The disclosed example includes intentionally introducing additional noise into the elevator car  22  depending on the position of the elevator car  22  to eliminate or at least reduce the changes in noticeable noise within the elevator car  22  as the car  22  moves relative to the machine  26 . 
       FIG. 2  graphically illustrates a noise profile  40  that shows changing noise levels with the changing vertical position of the car  22  within the hoistway  24 . A first plot  42  represents the noise level noticeable within the elevator car  22  as caused by operation of the machine  26 . In this example, the higher the elevator car rises, the greater the noise level introduced by the operation of the machine  26  becomes. If no other noise were intentionally introduced into the elevator car  22 , the plot  42  would represent the total noticeable noise level within the elevator car  22  in some examples. 
     The disclosed example includes intentionally introducing additional noise into the elevator car  22  in an amount that depends on the position of the elevator car  22 .  FIG. 2  shows a plot  44  of intentionally introduced compensating noise. The introduced noise shown at  44  is greatest when the car is near a lowest position in this example. The introduced noise shown at  44  and the machine noise shown at  42  result in a total noticeable noise within the elevator car  22  shown by the plot  46 . In this example, the total noise  46  that is noticeable within the elevator car  22  is generally consistent along the entire travel of the car  22  within the hoistway  24 . The combined effects of the machine noise shown at  42  and the intentionally introduced noise shown at  44  results in a generally consistent total noise level  46  within the elevator car  22 . 
     The disclosed example departs from traditional thinking, which has been to reduce the amount of noise noticeable within an elevator car  22 . By intentionally introducing noise, the disclosed example goes directly contrary to many approaches in elevator system design. Rather than attempting to eliminate the noise introduced by operation of the machine  26 , the disclosed example introduces additional, compensating noise to minimize the effects of any noticeable change in noise level within the elevator car  22  as the car  22  moves relative to the machine  26 . The introduction of a defined amount of additional noise that provides for a consistent total noise level within the elevator car actually reduces the passenger&#39;s perception of noise and increases the sound quality inside the elevator car. 
     One example includes introducing a broadband noise to compensate for the changes in noticeable noise caused by changes in distance from the machine. A broadband noise in one such example is characterized by spectrally white content in the frequency range of interest. 
     One example embodiment utilizes existing elevator system components as a source for the introduced noise. In  FIG. 1 , the guide rail  34  has one portion  50  above another portion  52 . A surface characteristic on each of the portions  50  and  52  is designed to cause interaction with the guidance components  36 , for example, to introduce additional noise that can be noticed within the elevator car  22  as the car moves within the hoistway  24 . In this example, the portion  50  of the guide rail  34  has a first surface characteristic  54 , which may be a desired roughness, for example, that results in noise generation as the car moves along the guide rail. The guide rail portion  52  has another surface characteristic  56 , which in this example includes an increased roughness for providing an increased level of sound as the elevator car  22  moves further away from the machine  26 . 
     The example of  FIG. 1  also includes deflector sheaves  58 ,  60  and  62 . The sheave  58  travels with the elevator car  22  within the hoistway  24 . The sheave  62  is associated with a counterweight  64 . The deflector sheaves rotate as the load bearing member  32  passes over them. In this example, at least a portion of the surface of the load bearing member  32  is altered so that interaction between the load bearing member  32  and at least the deflector sheave  58  results in additional noise generation as the car  22  moves further away from the machine  26 . Another example includes variations in sheave components to provide different noise levels at different heights in the hoistway  24 . Given the particular roping arrangement and the components selected for an elevator system, those skilled in the art who have the benefit of this description will be able to select how to design those components to provide additional noise when the elevator car is at selected positions within the hoistway. 
     One example includes using a first component to introduce compensating noise when the elevator car  22  is within a first range of the machine  26 . A second component adds more noise when the car  22  is within a second, further range of the machine  26 . This example includes using more noise sources for louder noticeable levels of compensating noise as needed to achieve an overall total noise profile. 
     Another example includes a source of noise not directly associated with operating elevator system components. Such an additional source of noise may be incorporated into the elevator car  22  or appropriate locations within the hoistway  24  for introducing the additional level of noise desired for a particular elevator car position within the hoistway  24 . One such example includes a speaker used to generate white noise that can be heard in the elevator car  22 . 
     In another example, in case of very long hoistways, the noise profile may be flattened near the top of the hoistway and then gradually allowed to reduce in amplitude as the car gets further and further away from the machine. The rate of change of noise is controlled by the amount of injected noise at any point in the hoistway. Those skilled in the art who have the benefit of this description will be able to customize noise generation to achieve a desired noise profile. 
     The disclosed examples provide ways of reducing or avoiding undesirable changes in the level of noise noticeable within an elevator car as the car moves relative to a machine supported within the hoistway. One advantage to the disclosed examples is that they do not require redesigning the machine itself or the structure used to support the machine within the hoistway. Another advantage to the disclosed examples is that they utilize existing elevator system components in a new way to achieve a desired noise profile within an elevator car throughout travel along a hoistway. 
     The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this invention. The scope of legal protection given to this invention can only be determined by studying the following claims.