WO2012071041A1

WO2012071041A1 - Brake with adjustable torque

Info

Publication number: WO2012071041A1
Application number: PCT/US2010/058018
Authority: WO
Inventors: Benjamin Watson
Original assignee: Otis Elevator Company
Priority date: 2010-11-24
Filing date: 2010-11-24
Publication date: 2012-05-31

Abstract

A brake having a housing, a movable plate movable relative to the housing, at least one spring disposed in the housing and urging the movable plate away from the housing, a coarse and fine adjustment mechanism for adjusting the compression of the spring. The fine adjustment mechanism adjusts the compression of the spring less than the coarse adjustment mechanism.

Description

BRAKE WITH ADJUSTABLE TORQUE

BACKGROUND OF THE INVENTION

[001] This invention relates to a brake, and more specifically to an elevator brake assembly which is capable of brake torque adjustment.

[002] In many elevator applications setting a precise brake torque ensures proper operation of the brake within the system. If the brake torque is too high, the elevator may stop the elevator car too abruptly. If the brake torque is too low, the elevator braking distance may be too high. In either event, the brake may not meet code and safety requirements.

[003] One current solution is to set the brake torque at the factory, during

manufacturing. While factory setting the brake torque provides consistency, one disadvantage of this solution is that changes in the field may occur that could require a change to the brake torque value. For example, a customer may wish to add features to the elevator car that makes the elevator car heavier than anticipated.

[004] Another current solution is to have a field mechanic adjust each brake at the jobsite during installation. The appropriate torque, or spring compression, required for the brake can be calculated based on certain contract details including rise of the elevator, weight of the car, and the duty load of the system. While field setting the brake torque can accommodate any late modifications to the elevator system, one disadvantage of this solution is inconsistency. Different mechanics may torque the brake differently. These variations could be significant since the coarse adjustment mechanism of this current solution allows the brake to be adjusted over its full range of torque values.

SUMMARY OF THE INVENTION

[005] The present invention is directed to adjustment of a brake. According to one aspect of the invention, a brake comprises a housing, a movable plate adjacent and movable relative to the housing, at least one spring disposed in the housing and urging the movable plate away from the housing, a coarse adjustment mechanism, and a fine adjustment mechanism. Both adjustment mechanisms adjust the compression of the spring, however, the fine adjustment mechanisms can adjust the compression of the spring less than the coarse adjustment mechanism.

[006] Alternatively in this or other aspects of the invention, the fine adjustment mechanism is embedded within the coarse adjustment mechanism. This may be accomplished in the form of a set screw.

[007] Alternatively in this or other aspects of the invention, the coarse adjustment mechanism may control up to 100% of the total spring compression, and further alternatively between 50% and 100%.

[008] Alternatively in this or other aspects of the invention, the fine adjustment mechanism may control up to 20% of the total spring compression, and further alternatively between 5% and 10%. [009] Alternatively in this or other aspects of the invention, the coarse adjustment mechanism adjusts the compression of a first spring and the fine adjustment mechanism adjusts the compression of a second spring.

[010] Alternatively in this or other aspects of the invention, the coarse adjustment mechanism and the fine adjustment mechanism both adjust the compression of a single spring.

[011] Alternatively in this or other aspects of the invention, the brake may be any of a variety of brakes including, but not limited to a disc brake, caliper brake, or clutch brake.

[012] According to yet another aspect of the invention, a method for adjusting the spring compression in a brake comprises performing coarse brake adjustment at a first time, and fine brake adjustment at a second time. The fine brake adjustment at a second time is occurs later than the coarse adjustment at a first time.

[013] Alternatively in this or other aspects of the invention, the coarse adjustment of the brake occurs while the brake is manufactured.

[014] Alternatively in this or other aspects of the invention, the fine adjustment of the brake occurs during installation or maintenance of the brake in the field.

[015] Alternatively in this or other aspects of the invention, the fine adjustment of the brake occurs during installation or maintenance of the brake in the field. [016] Alternatively in this or other aspects of the invention, the method for brake adjustment further comprises preventing coarse brake adjustment after the first time.

BRIEF DESCRIPTION OF THE FIGURES

[017] Fig. 1 schematically shows an exemplary elevator system;

[018] Fig. 2 shows an exemplary elevator brake;

[019] Fig. 3 is a detailed cross section of the brake as indicated in Fig. 2 and showing one possible arrangement of the adjustment mechanism; and

[020] Fig. 4 portrays the bottom of an exemplary elevator brake housing unobstructed by the adjacent moving part [021] Fig. 5 is the detailed cross section of the brake as indicated in Fig. 4 and showing another possible adjustment mechanism.

DETAILED DESCRIPTION OF THE FIGURES

[022] Figure 1 is an exemplary illustration of an elevator system 20 including an elevator car 22 and a counterweight 24. Components not relevant to the present invention (e.g. controller, safeties, rails, etc.) will not be discussed. At least one tension member 26 supports the weight of the elevator car 22 and the counterweight 24 in a known manner. The illustration also portrays the location of the elevator machine 18 at the top of the hoistway. The tension member 26 is supported on the machine sheave which is coupled to the machine shaft. The elevator car 22 and counterweight 24 are moved by rotating the machine shaft, which in turn causes the tension member 26 to move due to the frictional forces between the tension member 26 and the machine sheave. Figure 1 portrays an elevator system with an overslung roping arrangement, but the present invention could be used with other arrangements, such as an underslung arrangement. Similarly, although Figure 1 portrays a 2: 1 roping arrangement, the present invention could be used in systems with other roping arrangements. Also, the present invention is not limited to use in an elevator system.

[023] Figure 2 illustrates selected portions of an elevator machine 60 and an elevator brake 30. In the example, the elevator machine 60 includes a motor 64 that rotationally drives a shaft 66 about an axis 62. A sheave 68 on the machine shaft 66 rotates with the machine shaft 66 to raise or lower a cab in a known manner. The machine shaft 66 extends into the elevator brake assembly 30. The brake assembly includes a rotor 32 that is coupled for rotation in a known manner with the machine shaft 66. The brake assembly 30 selectively applies a braking force on the machine shaft 66 or a coupled rotating body to prevent rotation of the shaft 66. The elevator brake 30 includes a moving plate 38 for clamping the rotor 32 to apply a braking force on the machine shaft 66. Bias members 40, such as springs, bias the moving plate 38 in a brake- applying direction toward the rotor 32. The rotor 32 may include brake lining 42 for wear resistance when in contact with the braking surface 44.

[024] The controller (not shown) selectively activates an electromagnet 36 to overcome the spring force provided by the springs 40. When the machine shaft 66 starts rotating, the motion separates the rotor 32 from the braking surface 44, allowing the rotor 32 to rotate freely. When the electromagnet 36 is turned off, the springs 40 actuate the moving plate 38 to clamp the rotor 32 against the braking surface 44. The moving plate 38, springs 40, and electromagnet 36 are retained in a housing 34 that is secured to the machine stand. [025] Although the exemplary brake shown in Fig. 2 is a disc brake, the present invention could be used in any type of brake assembly in which a spring urges a first element against a second element to apply a braking force. Other suitable brake assemblies that could utilize the present invention include clutch brakes and caliper brakes.

[026] Figure 3 portrays the cross sectional view of a brake having a housing 34 that contains a spring 40. The housing 34 is commonly made of steel or cast iron, but may be made of any material. The spring 40 resides within an aperture 46 in the housing, with one end of the spring 40 contacting a movable plate 38 which is adjacent to the edge of the housing 34. The other end of the spring 40 is confined by a plunger 54 connected to at least one adjustment mechanism. The brake torque, or how much the spring 40 is compressed and urges against the movable plate 38, depends on the adjustment mechanism which controls the height of the plunger 54.

[027] FIG. 3 shows that the adjustment mechanism comprises both a coarse and fine adjustment mechanism acting on a single spring 40. The coarse and fine adjustment mechanisms are controlled by separate set screws. The outer screw of the two set screws can act as the coarse adjustment mechanism 50 (or, alternatively, the fine adjustment mechanism), and the inner screw embedded within the outer screw can act as the fine adjustment mechanism 52 (or, alternatively, the coarse adjustment mechanism). The coarse adjustment mechanism 50, which mounts into the aperture 46 using threads in the aperture 46 and on the set screw, may allow for adjustment up to 100% of the total spring compression and alternatively around 50% to 100% of the total spring compression. Similarly, the fine adjustment mechanism 52, which extends through a threaded opening 48 in the course adjustment mechanism 50, may allow for adjustment up to 20%, and alternatively around 5-10% of the total spring compression. Due to the nature of the set screw, the fine adjustment mechanism 19 is limited in part based on the length of the threads on the inner screw.

[028] By using a coarse adjustment mechanism 18 with an embedded fine adjustment mechanism 19, mechanic access to the coarse adjustment mechanism 18 will be blocked, thereby preventing coarse adjustment in the field. Another way to limit the mechanic to strictly fine adjustment includes placing a cover over the top of the coarse adjustment mechanism 18 so that the mechanic is only able to access the inner screw exposed above the cover. Similarly, the coarse adjustment mechanism 50 could use a different tool (ideally a tool that the mechanic in the field does not typically have) than the tool used adjust the fine adjustment mechanism (ideally a tool the mechanic in the field does have). Finally, the coarse adjustment mechanism 50 could be glued into place once it is set at the correct spring compression.

[029] Fig. 4 portrays the bottom of an exemplary brake housing with the adjacent movable plate 38 removed. This view of the brake housing is the opposite of that in Fig. 2 which looks at the brake from the top of the housing. Springs 40 may be located adjacent to each other In an alternate embodiment, shown in Figure 5, the coarse and fine adjustment mechanisms 50, 52 are separate and act on different springs 40, 40' contacting the same movable plate 38. In one possible arrangement, the housing 34 contains two apertures 46, 46' that receive springs, 40, 40', which may be adjacent to each other. The coarse adjustment mechanism 50 comprises a threaded screw fixed to a plunger 54 that can engage the top of the spring 40. The walls of the aperture 46 are threaded such that tightening the screw compresses the spring 40. Similar to the coarse adjustment mechanism 50, the fine adjustment mechanism 52 also contains a screw fixed to a plunger 54' that can engage the top of the spring 40', such that as the screw is tightened within the threaded aperture 46', the compression force of the spring 40' increases. In one possible arrangement, the two springs 40, 40' within the housing 34 are alike; however, the two screws have different thread lengths. The screw with the longer thread will have a greater range of adjustment of the spring compression, whereas the screw with the shorter thread will have a limited range of adjustment, and therefore limited compressibility of the spring.

[030] Alternatively, the screws for the coarse and fine adjustment mechanisms 50, 52 could be alike, and the two springs 40, 40' could be different. The springs would be selected such that the spring 40 acted on by the coarse adjustment mechanism 50 will be fully compressed when the screw is fully engaged, and the spring 40' acted on by the fine adjustment mechanism 52 will be only partially compressed when the screw is fully engaged. To ensure proper adjustment in such an arrangement, the coarse adjustment mechanism 50 can be distinguished from the fine adjustment mechanism 52 in a variety of ways, for example by coloring the screw, by placing a cover over the coarse adjustment screw mechanism 50, by requiring the use of a different tool to operate the coarse adjustment mechanism 50 than the tool used to operate the fine adjustment mechanism 52. This allows for adjustment of the coarse adjustment mechanism 50 at some first time, such as during manufacture in the factory, and adjustment of the fine adjustment mechanism 52 at some later time, such as by a mechanic during installation in the field or maintenance.

Claims

1. A brake comprising:

a housing

a movable plate adjacent and movable relative to the housing

at least one spring disposed in the housing and urging the movable plate away from the housing

a coarse adjustment mechanism that can adjust the compression of the spring

a fine adjustment mechanism that can adjust the compression of the spring less than said coarse adjustment mechanism.

2. The brake according to claim 1 wherein the fine adjustment mechanism is embedded within the coarse adjustment mechanism in the form of a set screw.

3. The brake according to claim 1 wherein the range of the coarse adjustment mechanism is up to around 100% of the total spring compression.

4. The brake according to claim 1 wherein the range of the coarse adjustment mechanism is around 50% - 100% of the total spring compression.

5. The brake according to claim 1 wherein the range of the fine adjustment mechanism is up to around 20% of the total spring compression.

6. The brake according to claim 1 wherein the range of the fine adjustment mechanism is around 5% - 10% of the total spring compression.

7. The brake according to claim 1 wherein the coarse adjustment mechanism adjusts the compression of a first spring, and the fine adjustment mechanism adjusts the compression of a second spring.

8. The brake according to claim 1, wherein the coarse adjustment mechanism and the fine adjustment mechanism adjust the compression of a single spring.

9. The brake according to claim 1 wherein the brake is a disc brake, a caliper brake, or a clutch brake.

10. A method for adjusting spring compression in a brake comprising:

performing coarse brake adjustment at a first time,

performing fine brake adjustment at some second time later than the first time.

11. The method according to claim 10 wherein the coarse brake adjustment occurs during manufacturing of the brake.

12. The method according to claim 10 wherein the fine brake adjustment occurs during

installation or maintenance of the brake in the field.

13. The method according to claim 10, further comprising the step of preventing coarse brake adjustment after the first time.