SAFETY BRAKE CONFIGURATION FOR ELEVATOR APPLICATION

Abstract

An adjacent safety configuration for an elevator includes a second pair of safeties displaced from a first pair of safeties by at least 0.1 seconds of travel time at a rated speed of the elevator. An adjacent safety configuration for an elevator including a second pair of safeties displaced from the first pair of safeties to provide a predetermined time period before the second pair of safeties pass over a point on a guide rail previously passed over by the first pair of safeties to permit the guide rail surface to decrease by a predetermined temperature. A method of spacing an adjacent safety configuration for an elevator system including de-rating a pair of trailing safeties with respect to a pair of leading safeties as a function of a rated speed of the elevator and a spacing between the pair of trailing safeties and the pair of leading safeties.

Claims

1. An adjacent safety configuration for an elevator comprising: a first safety; and a second safety displaced from the first safety to provide a predetermined time period before the second safety passes over a point on a guide rail previously passed over by the first safety to permit the guide rail surface to decrease in temperature.

2. The adjacent safety configuration as recited in claim 1, wherein the first safety is leading safeties and the second safety is the trailing safeties when the elevator is travelling downwards.

3. The adjacent safety configuration as recited in claim 1, wherein the second safety is displaced from the first safety by between 1-2 meters.

4. The adjacent safety configuration as recited in claim 1, wherein the second safety is displaced from the first safety by at least 1 meter.

5. The adjacent safety configuration as recited in claim 1, wherein the second safety is displaced from the first safety by at least 0.1 seconds of travel time at a rated speed of the elevator.

6. The adjacent safety configuration as recited in claim 1, wherein the first safety and the second safety are located below an elevator cab.

7. The adjacent safety configuration as recited in claim 1, wherein the first safety and the second safety are located above an elevator cab.

8. An adjacent safety configuration for an elevator comprising: a first pair of safeties; and a second pair of safeties, the second pair of safeties displaced from the first pair of safeties by at least 0.1 seconds of travel time at a rated speed of the elevator.

9. The adjacent safety configuration as recited in claim 8, wherein the first pair of safeties are leading safeties and the second pair of safeties are the trailing safeties.

10. The adjacent safety configuration as recited in claim 8, wherein the second pair of safeties are displaced from the first pair of safeties by between 1-2 meters.

11. The adjacent safety configuration as recited in claim 8, wherein the second pair of safeties are displaced from the first pair of safeties by at least 1 meter.

12. The adjacent safety configuration as recited in claim 8, wherein the first pair of safeties and the second pair of safeties are located below an elevator cab.

13. The adjacent safety configuration as recited in claim 8, wherein the first pair of safeties and the second pair of safeties are located above an elevator cab.

14. A method of configuring an adjacent safety of an elevator system comprising: de-rating a pair of trailing safeties with respect to a pair of leading safeties as a function of a rated speed of the elevator and a spacing between the pair of trailing safeties and the pair of leading safeties.

15. The method as recited in claim 14, wherein the spacing between the pair of trailing safeties and the pair of leading safeties provides at least 0.1 seconds of travel time at the rated speed of the elevator.

16. The method as recited in claim 14, wherein de-rating the pair of trailing safeties with respect to the pair of leading safeties includes rating the braking effectiveness of the pair of trailing safeties to be less than the pair of leading safeties.

17. The method as recited in claim 14, wherein the second pair of safeties are displaced from the first pair of safeties to provide a predetermined time period before the second pair of safeties pass over a point on a guide rail previously passed over by the first pair of safeties to permit the guide rail surface to decrease by a predetermined temperature.

18. The method as recited in claim 14, further comprising locating the pair of trailing safeties and the pair of leading safeties below the elevator cab, and a third pair of safeties above the elevator cab.

19. The method as recited in claim 14, further comprising locating the pair of trailing safeties and the pair of leading safeties above the elevator cab, and a third pair of safeties below the elevator cab.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Various features will become apparent to those skilled in the art from the following detailed description of the disclosed non-limiting embodiment. The drawings that accompany the detailed description can be briefly described as follows:

[0026] FIG. 1 is a schematic view of an embodiment of an elevator system according to one disclosed non-limiting embodiment;

[0027] FIG. 2 is a schematic view of an elevator with an adjacent safety configuration of an elevator system according to one disclosed non-limiting embodiment;

[0028] FIG. 3 is a schematic view of an elevator with an adjacent safety configuration of an elevator system according to another disclosed non-limiting embodiment;

[0029] FIG. 4 is a schematic view of an elevator with an adjacent safety configuration of an elevator system according to another disclosed non-limiting embodiment;

[0030] FIG. 5 is a schematic expanded view of an adjacent safety configuration;

[0031] FIG. 6 is a schematic view of a temperature profile for an adjacent safety according to one embodiment;

[0032] FIG. 7 is a schematic view of a temperature profile for an adjacent safety according to one embodiment;

[0033] FIG. 8 is a graphical representation of example spacing between safeties and the Coefficient of friction of brake shoe/guide rail interfaces.

DETAILED DESCRIPTION

[0034] FIG. 1 schematically illustrates an elevator system 10. The elevator system 10 includes an elevator 12 located in a hoistway 14. The hoistway 14 includes one or more guide rails 16 interactive with one or more guide shoes 18 of the elevator 12 to guide the elevator 12 along the hoistway 14. A suspension member 20, typically a rope and/or a belt, suspends the elevator 12 in the hoistway 14. It should be appreciated that although particular systems are separately defined, each or any of the systems can be otherwise combined or separated via hardware and/or software. It should also be appreciated that although one suspension member 20 is shown, multiple suspension members 20 may be utilized. The suspension member 20 is routed over one or more sheaves 22 thence to a counterweight 24 which may also be disposed in the hoistway 14. One or more of the sheaves may be a drive sheave 26, operably connected to a machine 28 to control the elevator 12 along the hoistway 14.

[0035] The elevator system 10 includes a safety brake system 30 disposed, in one embodiment, to engage the guide rails 16 to stop movement of the elevator 12 in response to certain select conditions such as an overspeed or other such situation.

[0036] With reference to FIG. 2, in one disclosed non-limiting embodiment, the safety brake system 30 includes two pairs of safeties 40, 50 below a lower elevator cab 60 and a third pair of safeties 70 above an upper elevator cab 62 of a double deck elevator. It should be appreciated that although a double deck cab is illustrated, a single deck cab will also benefit herefrom. Further, leading and trailing are utilized herein with respect to the downward travelling elevator.

[0037] The two pairs of safeties 40, 50 may be referred to herein as an adjacent safety configuration 80 as the two pairs of safeties 40, 50 are both located on one side, e.g., below (FIG. 2) or above (80A; FIG. 3), the elevator cab 60, 62. Each safety in each respective pair of safeties 40, 50, 70 engage one of the respective guide rails 16 and are typically located inboard of the respective roller guides 80, 82, i.e., closer to the elevator cab 60, 62. It should be appreciated that other arrangements such as a tripledeck elevator 12B (FIG. 4) with a at least one adjacent safety configuration 80B between cabs 60, 62, 63 will also benefit herefrom.

[0038] For relatively high-speed applications, e.g., 10 m/s or more, the trailing safeties 50 of the adjacent safety configuration 80 may exhibit degradation of performance due to operation on the guide rail 16 that has been heated by prior interaction with the leading safeties 40. The degradation of performance due to heating of the guide rail 16 by prior interaction with the leading safeties 40, is minimized by spacing the pair of trailing safeties 50 from the pair of leading safeties 40 to provide a predetermined time period therebetween. The time period permits the guide rail surface to cool subsequent to passage of the leading safeties 40 to improve the effectiveness of the trailing safeties 50. That is, the spacing increases the overall stopping capacity of the safety brake system 30, compared to the conventional close packaging of the safeties.

[0039] In one embodiment, at least 0.1 seconds of travel time is provided between the pair of trailing safeties 50 and the pair of leading safeties 40 at the rated speed of the elevator. In these relatively high-speed embodiments, a distance X between the pair of trailing safeties 50 and the pair of leading safeties 40 is between about 1-2 meters (FIG. 5). The trailing safeties 50 thereby contact the same portion of the guide rail 16 only after that portion of the guide rail 16 has been permitted to decrease by a predetermined temperature.

[0040] The time period between passage of the pair of leading safeties 40 then the passage of the pair of trailing safeties 50 may alternatively, or additionally, be utilized to de-rate the trailing safeties 50 with respect to the leading safeties 40 as a function of a rated speed of the elevator 12 and the spacing between the safeties 40, 50. That is, the braking capacity of the pair of trailing safeties 50 may be de-rated in the calculation of the overall stopping capacity of the safety brake system 30 since the pair of trailing safeties 50 will be relatively less effective than the leading safeties 40. The spacing between the pair of trailing safeties 50 with respect to the pair of leading safeties 40, and the de-rating of the pair of trailing safeties 50, facilitates the selection, or calibration, of the pair of trailing safeties 50 to achieve a desired capacity for the overall safety brake system 30. For example, the trailing safeties 50 may be selected as a function of elevator speed and spacing to be different than the pair of leading safeties 40 to achieve a desired stop.

[0041] With reference to FIG. 6, in one example in which the leading safeties 40 are spaced from the trailing safeties 50 by 350 mm, a peak temperature difference between the leading safeties 40 and the trailing safeties 50 are relatively greater than when the spacing is increased to 900 mm (FIG. 7). That is, the temperature difference is less pronounced when the spacing is increased. The spacing between the leading safeties 40 from the trailing safeties 50 permits an associated de-rating of a coefficient of friction at the brake/guide rail interface (COF) for the trailing safeties 50 (FIG. 8).

[0042] Determination of the relationship between safeties 40, 50 facilitates determination of the overall safety brake system 30 stopping capacity effectiveness to efficiently handle the load in a safe and code compliant system. Further, maximization of the stopping capacity of the safety brake system 30 permits relatively fewer safeties and less weight, or relatively higher capacity elevator cabs.

[0043] The use of the terms a, an, the, and similar references in the context of description (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or specifically contradicted by context. The modifier about used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., it includes the degree of error associated with measurement of the particular quantity). All ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other.

[0044] Although the different non-limiting embodiments have specific illustrated components, the embodiments of this invention are not limited to those particular combinations. It is possible to use some of the components or features from any of the non-limiting embodiments in combination with features or components from any of the other non-limiting embodiments.

[0045] It should be appreciated that like reference numerals identify corresponding or similar elements throughout the several drawings. It should also be appreciated that although a particular component arrangement is disclosed in the illustrated embodiment, other arrangements will benefit herefrom.

[0046] Although particular step sequences are shown, described, and claimed, it should be understood that steps may be performed in any order, separated or combined unless otherwise indicated and will still benefit from the present disclosure.

[0047] The foregoing description is exemplary rather than defined by the limitations within. Various non-limiting embodiments are disclosed herein, however, one of ordinary skill in the art would recognize that various modifications and variations in light of the above teachings will fall within the scope of the appended claims. It is therefore to be understood that within the scope of the appended claims, the disclosure may be practiced other than as specifically described. For that reason the appended claims should be studied to determine true scope and content.