Brake for an elevator system

Abstract

The invention relates to a brake (10), in particular a safety brake, suitable for an elevator system (1) having a guide rail (4), said brake (10) having a caliper design and said brake (10) comprising: two brake shoes (14), a first brake lever (12A) and a second brake lever (12B), which are rotatably connected to each other via a swivel joint (13), a spring arrangement (15), which is designed to impact the first brake lever (12A) opposite the second brake lever (12B) in a first direction (R1), an actuator arrangement (16), which is designed to selectively impact the first brake lever (12A) opposite the second brake lever (12B) in a second direction (R2), wherein the brake levers (12A, 12B) are designed to transition the brake shoes (14) between a first released operating state (I) and a second active operating state (II) as a factor of the impact by the spring arrangement (15) and the actuator arrangement (16), wherein the spring arrangement (15) comprises at least one plate spring assembly (51) having one or more plate springs (59).

Description

[0001] The invention relates to a brake for an elevator system, in particular a safety brake.

[0002] A safety brake is used to decelerate the car of an elevator system in an emergency, for example, if excessive speed is detected or, in extreme cases, if the suspension elements break. In modern elevators with multiple cars in a shaft, the safety brake is also used to quickly decelerate if two cars are not sufficiently separated from each other. The safety brake typically provides maximum braking force; braking force adjustment is not generally required with safety brakes.

[0003] Safety brakes usually consist of wedges or eccentrics mechanically applied to the rail which automatically retract as the car travels to a defined end point. This causes an elastic element such as a disc spring assembly or the housing itself to expand to the extent that the desired normal force is created to generate the necessary braking force between the friction linings and the rail. The spring characteristic curve can be very hard, as only manufacturing tolerances and wear on the brake linings need to be compensated for. This allows the spring elements to be made relatively small and cost-effective, and the operating travel is very short. However, these safety brakes have the disadvantage that the retraction travel of the wedges or eccentrics must always be covered from the time the brake is activated until it is fully effective. The car may accelerate further during the retraction process.Both of these can cause the elevator car to come to a stop later. Once the brake is applied, it can only be deactivated by moving the elevator car in the opposite direction, which makes any emergency rescue difficult.

[0004] Alternatively, brakes without wedges or eccentrics are known. Here, the required normal force is applied directly to the brake pads. The spring elements are also usually small and inexpensive, and the brake pads are held open by a linear movement. This design typically allows only small air gaps when the brake is open. However, the relative movements between the car and the guide rail are significantly larger. Therefore, the brake would have to be floating, and the constant grinding of the brake pads would have to be tolerated. However, noise, abrasion, and wear are to be expected.

[0005] EP 2 338 821 A1 discloses a safety brake with a caliper design. This comprises two brake levers that can be rotated relative to one another. At a first end of each brake lever, brake pads are provided, between which the guide rail is arranged. At a second end of the brake lever, springs and / or actuators are provided, which selectively urge the brake levers apart or towards one another. In the latter case, the brake is activated. This type of safety brake has design-related advantages, in particular, no components are used that are displaced transversely to the braking force during actuation. Instead, the brake shoes are rotated about an axis of rotation that runs parallel to the direction of the braking force, which enables good absorption of the braking forces. A disadvantage, however, is the tendency of the coil spring to buckle, which is exacerbated by the relative rotation of the brake levers.Complex measures to reduce this include either a lateral guide for the coil spring or a hinged connection of the coil spring to the brake lever.

[0006] Further brakes with a pincer design are described in WO 2015 / 052109 A1, JP H09 267983 A, and CN 205 114 750 U. WO 2010 / 003466 A1 describes a safety gear for an elevator system. A force storage element comprises a plurality of disc springs arranged one behind the other.

[0007] The object of the present invention is to provide an improved safety brake with a pincer design. The object underlying the invention is achieved by a brake and a method according to the independent claims; preferred embodiments emerge from the subclaims and the description.

[0008] The brake according to the invention is in particular a safety brake and is suitable for an elevator system with a guide rail. The brake is designed as a pliers design. The brake comprises: two brake shoes, a first brake lever and a second brake lever, which are rotatably connected to one another via a pivot joint, a spring arrangement which is designed to act on the first brake lever relative to the second brake lever in a first direction, and an actuator arrangement which is selectively designed to act on the first brake lever relative to the second brake lever in a second direction. The brake levers are designed to transfer the brake shoes between a first released operating state and a second active operating state depending on the actuation by the spring arrangement and the actuator arrangement. The spring arrangement comprises at least one disc spring assembly, each with one or more disc springs.

[0009] This takes advantage of the fact that disc springs are more robust than coil springs when it comes to lateral buckling. Due to their design, disc springs have a harder spring characteristic curve for comparable spring forces. Consequently, shorter travel distances are required to provide the forces. This has the advantage that pivoting the brake lever at a smaller angle is sufficient. Complex measures to reduce the tendency to buckling are therefore unnecessary.

[0010] Disc springs are understood to be springs according to the DIN 2093 standard. In particular, a disc spring has a length, viewed in the direction of action of the disc spring, that is less than the diameter of the disc spring.

[0011] The first brake lever has a first spring contact surface, and the second brake lever has a second spring contact surface, which serves to engage one of the at least one disc spring assembly. The spring contact surface can be formed by a separate element; therefore, it does not have to be formed integrally with the other areas of the brake lever. However, a rigid connection to the brake lever is preferred.

[0012] Furthermore, the brake is designed such that in a first operating state, the two spring contact surfaces exhibit a first pivoting relative to one another and in a second operating state, a second pivoting relative to one another, wherein the first pivoting and the second pivoting have different signs. This means, in particular, that during the transfer of the brake from the released operating state to the active operating state, the two spring contact surfaces are parallel. The pivoting (further designated by an angle specification) refers to the direction of view parallel to the axis of rotation of the two brake levers; the first pivoting has, for example, a positive value, while the second pivoting has a negative value.

[0013] The deflection is therefore understood as the angle that the two planes of the spring contact surfaces form with respect to each other. Mathematically, the deflection is defined as the intersection angle of two straight lines, each of which is perpendicular to a spring contact surface. If the two spring contact surfaces are aligned parallel to each other, the deflection is 0°. The smaller value is used, e.g., -5° instead of -175°.

[0014] The greater of the two pivots represents the maximum pivot, and the difference between the two pivots represents the pivot range, with the ratio of the pivot range to the maximum pivot being greater than 1.5. The spring contact surfaces are therefore pivoted through a pivot range that is greater than the maximum pivot. Accordingly, it is advantageous if the pivoting is as small as possible while the pivot range is as large as possible. The ratio of the pivot range to the maximum pivot is advantageously 2, which is the optimal value. With a value of 2, half of the full pivot range lies on one side and the other side of the parallel position.

[0015] Preferably, the amount of the first pivoting is a maximum of 6° and / or the amount of the second pivoting is a maximum of 6°.

[0016] The spring arrangement preferably comprises a guide element with a cylindrical guide section, wherein the guide section is received in a central opening of the disc spring assembly. The guide element holds the disc spring assembly with several disc springs radially together. A precisely cylindrical guide surface is not required; rather, interrupted guide surfaces, which, however, have an overall cylindrical envelope, are also sufficient.

[0017] The guide element preferably comprises a stop section, wherein the disc spring assembly is clamped between the stop section and the associated brake lever. In particular, the spring arrangement comprises two disc spring assemblies, wherein each disc spring assembly comprises a guide element with a stop section, wherein the two guide elements are firmly connected to one another. The distance between the stop sections of the two guide elements is in particular adjustable, in particular by means of a separate spacer element arranged between the two guide elements or by means of a threaded element. A separate spacer element can be arranged between the two guide elements. This enables a simple assembly option to be implemented. The two guide elements are preferably firmly connected to one another at their stop sections.The preload of the spring arrangement can be adjusted by carefully selecting the spacer element.

[0018] The disclosure further relates to a brake arrangement having an aforementioned brake and a guide rail which interacts with the brake.

[0019] The disclosure further relates to an elevator system with a car that can be moved within a shaft in one direction of travel. The car is guided by at least one guide rail. The elevator system comprises at least one brake of the aforementioned type.

[0020] The invention further relates to a method for assembling such a brake, the method comprising the following method steps: Inserting a first guide element into a central opening of the first disc spring assembly and applying the first disc spring assembly to the first brake lever; inserting a second guide element into a central opening of the second disc spring assembly and applying the second disc spring assembly to the second brake lever; fastening the two guide elements together.

[0021] In one embodiment of the method, the two guide elements are each fastened to each other at their stop section.

[0022] The invention is explained in more detail below with reference to the figures, in which Figure 1 a brake according to the invention in perspective view; Figure 2 the brake after Figure 1 in plan view; Figure 3 a brake lever of the brake Figure 1 in perspective view; Figure 4 two brake levers of the brake Figure 1in plan view a) during the released state of the brake, b) during the transition from the released to the active state of the brake, c) during the active state of the brake; Figure 5 the brake after Figure 1 in perspective view in a first phase of assembly; Figure 6 the brake after Figure 1 in perspective view in a second phase of assembly; Figure 7 an elevator system according to the invention with a brake according to Figure 1 .

[0023] Figure 7shows an elevator system 1 according to the invention. The elevator system 1 comprises a shaft 5 in which a car 2 is movably accommodated. The car 2 is guided by guide rails, whereby in principle one guide rail 4 can be sufficient. The car is driven via a cable drive with a cable 3 and a drive motor (not shown). The drive can also be implemented in another way, for example using a linear drive. Two brakes 10 according to the invention are arranged on the car 2, which brakes can be activated in particular when the car 2 has to be braked unexpectedly and quickly, for example in the event of a support element break. In this respect, the brake is in particular a safety brake. The braking force of such safety brakes cannot be dosed during operation.

[0024] The brake 10 is controlled by the Figures 1 to 6described in more detail. The brake 10 is designed as a caliper. For this purpose, the brake 10 has a first brake lever 12A and a second brake lever 12B. The two brake levers 12 are designed exactly identically in this case, but they do not have to be exactly identical. In the following, only one brake lever 12 is described as a representative of both brake levers 12A, 12B; the structure of the brake lever 12 can be seen in Figure 3 best recognize.

[0025] The brake lever 12 has an active section 21, a joint section 22 and an actuating section 23. On the active section 21 there is a possibility for fastening a brake shoe 14 (see Figures 1 and 2). In the present case, the possibility for fastening a brake shoe 12 is a brake shoe bore 31, to which the brake shoe 14 is pivotally fastened by means of a bolt. The axis Y of the brake shoe bore 31, which consequently represents the axis of rotation of the brake shoes 14, is aligned parallel to the direction of travel F (see Figure 2 ). At the joint section 22, the brake lever 12 has a joint bore 32, whereby the two brake levers 12 are connected to each other by means of a bolt and thus a pivot joint 13 (see Figure 2 ). The rotation axis X of the swivel joint is aligned parallel to the direction of travel F (see Figure 2 ).

[0026] At the actuating section 23, the brake lever 12 has a spring plate 24 with a spring contact surface 25, on which a spring arrangement 15 (see Figures 1 and 2) is applied. In the present case, spring arrangement 15 has two disc spring assemblies 51A, 51B. A circumferential guide edge 26 of the spring plate 24 delimits the spring contact surface 25. The guide edge 26 prevents springs of the adjacent spring arrangement 15 from breaking out laterally. Furthermore, the brake lever 12 comprises an actuator opening 28 on the actuating section 23, through which the actuating rod 62, defined further below, is passed. The joint section 22 is arranged between the actuating section 23 and the active section 21. The brake levers 12A, 12B are connected to two mounting plates 11 via the pivot joint 13. The brake 10 is fastened to the car 2 on the mounting plates 11. The brake levers 12 are configured such that the active sections 21 move towards one another when the actuating sections 23 move away from one another.In this respect, the kinematics of the present brake 10 differs from the kinematics of conventional pliers, e.g. a pipe wrench.

[0027] The basic function of the brake 10 can best be seen from the Figures 1 and 2 The guide rail 4 is arranged between the brake shoes 14, each of which is attached to one of the brake levers 12A, 12B (only in Figure 2 marked). The Figure 2shows the brake 1 in a first, released operating state. In this first operating state, the brake levers 12 keep the brake shoes 14 at a distance from the guide rail 4. For this purpose, the brake has an actuator arrangement 16 with an actuator 61 and an actuating rod 62. The actuator arrangement 16 is configured to actuate the two actuating sections 23 toward one another in the second direction R2, so that the respective active sections 21 of the two brake levers 12A, 12B are actuated away from one another. In the present example, the actuator 61 is designed as a hydraulic pull actuator, although other actuators are also possible.

[0028] The tensile force of the actuator is counteracted by a spring force of the disc spring assemblies 51A, 51B. The disc spring assemblies 51A, 51B act on the spring contact surface 25 and thus the actuating sections 23 in a first direction R1, moving them away from each other. When the brake is released, the effect (here the leverage) of the actuator arrangement 16 in the second direction R2 is stronger than the effect of the spring arrangement 15 in the first direction R1. When actuated, the force of the actuator 61 is eliminated; the actuator arrangement 16 can no longer sufficiently urge the two actuating sections 23 towards each other in the first direction R1. Due to the spring force of the disc spring assemblies 51, the brake shoes 14 are urged towards each other at the actuating sections 21 and clamp the guide rail 4 between them.

[0029] In the context of this exemplary embodiment, the first direction R1 is generally understood to mean that the spring contact surfaces 25 of the two brake levers 12A, 12B move away from each other. In the context of this exemplary embodiment, the second direction R2 is generally understood to mean that the spring contact surfaces 25 of the two brake levers 12A, 12B move toward each other.

[0030] The spring contact surfaces are of particular importance; reference is made below to the Figure 4 , in which the brake levers 12A, 12B are shown in isolation. Figure 4a shows the brake levers 12A, 12B in the first released operating state I, Figure 4c shows the brake levers 12A, 12B in the second active operating state II. In the Figure 4b the brake levers are shown in an intermediate position, which the brake levers 12A, 12B briefly assume during the transition from the first operating state to the second operating state.

[0031] Due to the rotation of the two brake levers, the pivoting of the two spring contact surfaces 25A, 25B relative to each other changes. To prevent the risk of bending, it is advantageous to always keep the pivoting as close as possible to a parallel alignment (angle α=0°). The parallel alignment is in Figure 4b shown. In the first operating state, the two spring contact surfaces 25A, 25B assume a first pivoting angle αI relative to each other, which in this case is approximately -5°. In the second operating state, the two spring contact surfaces 25A, 25B assume a second pivoting angle αII relative to each other, which in this case is approximately +5°. The amount of the first and second pivoting angles, and thus the maximum pivoting angle αmax, is 5°.

[0032] During the transition between the two operating states, the brake levers 12 rotate relative to each other by 10° (swivel range = 10°). Since the swivel from the parallel position of + / -5° in each direction represents half of the 10° swivel range, the ratio of swivel range to maximum swivel is maximized (here, this ratio assumes the optimal value of 2). Consequently, the largest possible swivel range is achieved with the smallest possible risk of buckling.

[0033] For comparison: In the brake described in EP 2 338 821 A1, the entire swivel range is on one side of the parallel position. For example, a swivel in the first operating state could be +2°, while a swivel in the second operating state could be +12°. Even if the swivel range is 10°, the maximum swivel is 12°. The aforementioned ratio of swivel range to maximum swivel is therefore 10 / 12, or approximately 0.83, and is therefore significantly more disadvantageous. The risk of buckling is greater, even when using comparable springs.

[0034] A ratio of 1.0 occurs when the first or second pivoting is 0°. If the parallel position is only achieved during the transition between the two operating states, the ratio is greater than 1. A ratio value of 2 represents the maximum and thus the optimal value.

[0035] If a flat spring contact surface is not available in a particular design, the above-mentioned angle specifications cannot be clearly derived from the geometry of the brake lever. In this case, a flat surface can be conceptually constructed to determine the angle. For the purposes of the present invention, it is essential that the constructed flat surface is aligned opposite to the angular position of the disc spring, since its angular position is ultimately what matters.

[0036] The assembly of the brake 10 is carried out using the Figures 5 and 6described. In a first step, the first disc spring assembly 51A is assembled. For this purpose, a first guide element 52A with an outer cylindrical guide section 53 is inserted into a central opening 58 of the disc springs 59 until an axial stop section 54 of the guide element 52A is in contact with the disc springs 59 on a first side. The axial stop 54 has a larger diameter than the opening 58 of the disc springs 59. On the other side, the disc springs 59 are placed against the spring contact surface 25A of the first brake lever 12A. The same steps are carried out for the second disc spring assembly 51B with the second brake lever 12B and a second outer cylindrical guide element 52B. The axial stop sections 54 of the two guide elements 52 are directed towards one another. The two guide elements 52A, 52B are then fastened to one another.This can be achieved by screwing together the mutually facing stops 54 (nut 57, screw 56). The screw 56 is passed through an opening 63 in the guide element. This creates a superior guide element from the two individual guide elements 52A, 52B. A spacer washer can be individually inserted between the two guide elements 52A, 52B as a spacing element, thereby adjusting the preload of the spring arrangement. Alternatively, to adjust the distance between the stops 54, the opening 63 in the guide element can be designed as a threaded hole with an internal thread complementary to the screw 56. The preload of the spring arrangement varies depending on the rotational position of the guide element 53 relative to the screw. The rotational position can be fixed using a lock nut.

[0037] The two brake levers 12A, 12B are bolted to the mounting plates 11, whereby the term "plate" is to be understood broadly and does not imply a flat shape. A central sleeve opening 27 on the spring plate 25 allows a largely unobstructed movement of the guide element 52 relative to the brake lever 12 axially (parallel to the first or second direction R1, R2). However, the central sleeve opening 27 can provide radial guidance (transverse to the first or second direction R1, R2). Radial and axial refer here to the approximate axis of the disc springs.

[0038] The rotational axis X between the brake levers 12 is aligned parallel to the direction of travel F, in which the braking force also acts. Therefore, the braking force has no effect on the relative rotational position of the brake levers.

[0039] The rotational axis Y between a brake shoe 14 and the associated brake lever 12 is aligned parallel to the direction of travel F, in which the braking force also acts. Therefore, the braking force has no effect on the rotational position of the brake shoes relative to the respective brake lever.

[0040] In particular, a disc spring has a length L, viewed in the direction of action of the disc spring, which is less than a diameter D of the disc spring. List of reference symbols

[0041] 1Elevator system 2Car 3 4Cable Guide rail 5Shaft 10Safety brake 11Mounting plate 12Brake lever 13Pivot joint 14Brake shoe 15Spring arrangement 16Actuator arrangement 21Active section 22Joint section 23Actuating section 24Spring plate 25Spring contact surface 26Circular spring guide edge 27Sleeve opening 28Actuator opening 31Brake shoe bore 32Joint bore 51Disc spring assembly 52Guide sleeve 53Guide section 54Stop section 55Spacer 56Screw 57Nut 58Central opening of the disc springs 59Disc spring 61Actuator 62Actuating rod 63Opening in the guide element XAxis of rotation of the brake lever YAxis of rotation of the brake shoes relative to the brake lever FDirection of travel L Length of the disc spring D Diameter of the disc spring

Claims

1. Brake (10), in particular a safety brake, suitable for an elevator system (1) having at least one guide rail (4), the brake (10) being configured in a pincer-type design, the brake (10) comprising: two brake shoes (14); a first brake lever (12A) and a second brake lever (12B), which are rotatably connected to one another via a pivot joint (13); a spring assembly (15) arranged to bias the first brake lever (12A) with respect to the second brake lever (12B) in a first direction (R1); an actuator assembly (16) arranged to selectively bias the first brake lever (12A) with respect to the second brake lever (12B) in a second direction (R2), wherein the brake levers (12A, 12B) are arranged to transfer the brake shoes (14) between a first released operating state (I) and a second active operating state (II) depending on the bias by the spring assembly (15) and the actuator assembly (16), wherein the spring assembly (15) comprises at least one disc spring pack (51) comprising respectively one or more disc springs (59), wherein the first brake lever (12A) comprises a first spring abutment surface (25A) and the second brake lever (12B) comprises a second spring abutment surface (25B) which is used for abutment of one of the at least one disc spring packs (51A, 51B), wherein the brake (10) is configured such that in the first operating state (I) the two spring abutment surfaces (25A, 25B) have a first angular positioning (αI) relative to each other and in the second operating state (II) have a second angular positioning (αII) relative to each other, wherein the first angular positioning (αI) and the second angular positioning (αII) have different signs, characterized in that the larger amount of the two angular positionings (αI, αII) represents a maximum angular positioning (αmax); and the amount of the difference (Δα) between the two angular positionings (αI, αII) represents a pivoting range (Δα), wherein the ratio of pivoting range to maximum angular positioning (Δα / αmax) is greater than 1.5, in particular 2.

2. Brake (10) according to claim 1, characterized in that the amount of the first angular positioning (αI) is at most 6° and / or in that the amount of the second angular positioning (αII) is at most 6°.

3. Brake (10) according to any one of the preceding claims, characterized in that the spring assembly (15) comprises a guide element (52) having a cylindrical guide section (53), wherein the guide section (53) is received in a central opening (58) of the disc spring pack (51).

4. Brake (10) according to any one of the preceding claims, characterized in that the guide element (52) comprises a stop section (54), wherein the disc spring pack (51) is clamped between the stop section (54) and the associated brake lever (12).

5. Brake (10) according to the preceding claim, characterized in that the spring assembly (15) comprises two disc spring packs (51A, 51B), wherein each disc spring pack (51A, 51B) comprises a guide element (52A, 52B) having a stop section (54), wherein the two guide elements (52A, 52B) are connected, in particular fixedly connected, to each other.

6. Brake (10) according to the preceding claim, characterized in that a distance between the stop sections (54) of the two guide elements can be adjusted, in particular by means of a separate spacer element (55) arranged between the two guide elements (52A, 52B) or by means of a threaded element (56).

7. Brake (10) according to claim 5 or 6, characterized in that the two guide elements (52A, 52B) are respectively firmly connected to one another at their stop sections (54).

8. Brake assembly, comprising: a brake (10) according to any one of the preceding claims and a guide rail (4).

9. Elevator system (1), comprising: a car (2) that can be moved in a direction of travel (F) within a shaft (5), wherein the car (2) is guided by at least one guide rail (4); and a brake (10) according to any one of claims 1 to 7.

10. Method for assembling a brake (10) according to any one of claims 5 to 7, comprising the following method steps: inserting a first guide element (52A) into a central opening (58) of the first disk spring pack (51A) and abutting the first disk spring pack (51A) against the first brake lever (12A); inserting a second guide element (52B) into a central opening (58) of the second disk spring pack (51B) and abutting the second disk spring pack (51B) against the second brake lever (12B); and attaching the two guide elements (52A, 52B) to each other.

11. Method according to the preceding claim, wherein the two guide elements (52A, 52B) are respectively attached to each other at their stop section.

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