Patent Grant
11845634
This application claims priority to European Patent Application No. 20382884.3, filed Oct. 7, 2020, and all the benefits accruing therefrom under 35 U.S.C. § 119, the contents of which in its entirety are herein incorporated by reference.
This disclosure relates to a safety brake device for use within a conveyance system such as an elevator system, and to a method of operating a safety brake in a safety brake device.
Many elevator systems include a hoisted elevator car, a counterweight, a tension member which connects the hoisted elevator car and the counterweight, and a sheave that contacts the tension member. During operation of such an elevator system, the sheave may be driven by a machine to move the elevator car and the counterweight through the hoistway, with their movement being guided by guide rails. Typically a governor is used to monitor the speed of the elevator car. According to standard safety regulations, such elevator systems must include an emergency braking device (known as a safety brake or “safety gear”) which is capable of stopping the elevator car from moving downwards, even if the tension member breaks, by gripping a guide rail.
The risks associated with freefall of an elevator car in an elevator system are particularly acute for elevator systems employed in high-rise buildings, where more significant over speed may occur due to the increased drop. The actuation of the safety brake is usually mechanically controlled. An elevator system employing a mechanical governor and mechanically-actuated safety brake is shown in
Electromechanical actuators have also been proposed, wherein a safety controller is in electrical communication with an electromagnetic component that can be controlled to effect movement of the safety brake via a mechanical linkage. It is an aim of the present disclosure to provide an improved safety brake device.
According to a first aspect of this disclosure there is provided a safety brake device for use in a conveyance system including a guide rail and a component moveable along the guide rail, the safety brake device comprising: a safety brake moveable between a non-braking position where the safety brake is not in engagement with the guide rail and a braking position where the safety brake is engaged with the guide rail; an actuator for the safety brake, the actuator comprising: a mounting portion for mounting the actuator to the component, a pad arranged to be moveable relative to the mounting portion between a first position spaced from the guide rail and a second position in contact with the guide rail, and at least one biasing member configured to apply a biasing force to move the pad from the first position to the second position; and a linkage mechanism coupled between the safety brake and the actuator such that, when the mounting portion is moving downwards relative to the guide rail, movement of the pad to the second position creates an upwards reaction force transmitted by the linkage mechanism to move the safety brake into the braking position; wherein the pad comprises a ferromagnetic material and the actuator further comprises an electromagnet operable to apply a magnetic field to the pad and thereby create a magnetic force acting against the biasing force to move the pad towards the first position.
Thus it will be appreciated by those skilled in the art that, if the electromagnet is turned off, for example if the component is detected to be moving too fast or accelerating at too great a rate, then the pad will move from the first position to the second position under the biasing force. The pad will therefore contact the guide rail, and due to the relative downwards motion of the mounting portion fixed to the component compared to the pad in contact with the guide rail, an upwards reaction force will be created and transmitted by the linkage mechanism to the safety brake, thereby moving the safety brake into the braking position to engage with the guide rail and stop motion of the component. It will be understood by the skilled person that the contact between the pad in the second position and the guide rail results in a frictional force between the pad and the guide rail, but this frictional force alone is not strong enough to cease motion of the component relative to the guide rail. In the second position, the pad has moved laterally to contact the guide rail but there may still be a degree of relative movement between them. It is the engagement of the safety brake with the guide rail that creates a much larger frictional force to bring the component to a stop. When the safety brake is in the non-braking position, the safety brake is spaced from the guide rail or in minimal contact so there is not an engagement functioning to achieve a frictional braking force that can stop the component. When the safety brake is in the braking position, the safety brake is brought into intentional hard contact with the guide rail to create an engagement functioning to achieve a frictional braking force sufficient to stop the component.
The disclosed safety brake device may require fewer components than prior art mechanical safety brake devices which may therefore reduce the space required by the safety brake device. In addition, the reduction in the number of components may reduce the cost on installation and service. As the safety brake and actuator are combined into a single device instead of being installed onto the component as two separate systems, this may further reduce cost. Further to this, the safety brake device set out in the present disclosure may have more modularity regarding the type of conveyance system it is to be used in. For example, the number of biasing members may be increased, or the force provided by the at least one biasing member may be altered.
The pad may have a high friction surface. This high friction surface may be the surface of the pad which contacts the guide rail when the pad is in the second position. For example, the high friction surface may be knurled or roughened.
It will be understood by the skilled person that the pad therefore provides two functions: the friction between the pad and the guide rail results in the upwards reaction force transmitted to the linkage mechanism and, as the pad is ferromagnetic, it can be arranged to complete the magnetic circuit of the electromagnet when in the first position. The electromagnet may be composed of an iron core which is surrounded by a coil of wire. When current flows through the coil, a magnetic field is generated by the electromagnet. The electromagnet may have a G-shaped or E-shaped iron core, or any other shape which is suitable.
In a set of examples, the pad is non-magnetic. It will be understood that the moveable pad being non-magnetic means that it does not include any permanent magnet. Hence the pad is not itself magnetically attracted to a ferrous guide rail. The inclusion of ferromagnetic material allows the non-magnetic pad to be magnetised in the presence of the magnetic field applied by the electromagnet, but the magnetic force pulls the pad towards the electromagnet and holds it in the first position against the biasing force. When the electromagnetic is turned off, the non-magnetic pad is no longer magnetised and the only force pushing the pad into contact with the guide rail is the biasing force i.e. no magnetic force. The absence of a permanent magnet can make the safety brake device smaller, cheaper and easier to adapt to different conveyance systems.
In various examples, the pad may include any ferromagnetic material such as iron, cobalt, nickel, or an alloy of any of these metals. In examples where the pad is non-magnetic, the pad may be fabricated from any ferromagnetic material such as iron, cobalt, nickel, or an alloy of any of these metals. In at least some examples the non-magnetic pad is made wholly from a ferromagnetic material.
In a set of examples, the electromagnet comprises an electrical coil and a ferromagnetic core, and the pad includes a reset portion that is arranged in the first position to form part of the ferromagnetic core. This arrangement enables the pad to complete the magnetic circuit of the electromagnet, thus assisting reset when the pad is re-aligned with the electromagnet such that it moves more easily from the second position back to the first position.
In a set of examples, the electromagnet is fixed relative to the mounting portion. The linkage mechanism may be connected to the pad or to the support. In this set of examples, therefore, when the electromagnet is turned off and the pad moves from the first position to the second position, the electromagnet stays fixed in its position within the safety brake device whilst the support, biasing member and pad move upwards relative to the fixed electromagnet and mounting portion. The linkage mechanism may therefore be either connected to the pad or support, as both the pad and support will move upwards relative to the mounting portion and therefore move the linkage mechanism to engage the safety brake.
In a set of examples, the pad is connected to a support which is movable upwards relative to the mounting portion in response to the upwards reaction force. In a set of examples, the safety brake device further comprises a bearing surface arranged between the support and the mounting portion which enables upwards movement of the support relative to the mounting portion. This surface may comprise, for example, linear roller bearings along which the support and therefore pad can move relative to the mounting portion. Alternatively, the surface may be any low friction surface which enables the support to move relative to the mounting portion.
In a set of examples, at least one guiding rod is arranged to connect the pad to the support so as to guide lateral movement of the pad from the first position to the second position relative to the support. In a set of examples, the at least one biasing member is connected to the support and to the pad. This arrangement enables the at least one biasing member to provide the biasing force to the pad which moves it from the first position to the second position in contact with the guide rail. The biasing member may be a spring or any other resilient member which can be configured to provide the biasing force to move the pad from the first position to the second position. More than one spring may be used, for example two springs may be used and connected at either end of the pad and support. The springs may be pre-compressed between the support and pad such that they provide a biasing force to the pad. The guiding rod is rigid and may therefore prevent the pad from falling due to gravity by providing a connection to the support. In a set of examples, the at least one guiding rod is arranged to guide the at least one biasing member. A guiding rod may be arranged to pass through the centre of a coil spring. The guiding rod may therefore act to prevent the spring from buckling by supporting the weight of the pad. The guiding rod may be connected to the support and pad with nuts.
In another set of examples, the electromagnet is connected to the support so as to be moveable relative to the mounting portion. In a set of examples, the linkage mechanism is connected to the electromagnet, to the pad, or to the support. Therefore, in this set of examples, when the electromagnet is turned off and the pad moves from the first to the second position, the electromagnet moves with the support, biasing member and pad upwards relative to the mounting portion. The linkage mechanism may therefore be either connected to the pad, electromagnet or support, as the pad, electromagnet and support will move upwards relative to the mounting portion and move the linkage mechanism to engage the safety brake.
In a set of examples, the electromagnet is connected to the support, and the at least one biasing member is connected to the support and to the pad, in a symmetrical arrangement such that the biasing force applied to move the pad from the first position to the second position is opposed by the magnetic force without applying a torque to the pad. This arrangement helps reduce any torque acting on the pad as the biasing member(s) may be arranged symmetrically about the electromagnet such that the biasing forces and magnetic force acting on the pad acted through the centre of the pad, preventing any rotation.
In a set of examples, the safety brake device further comprises a controller electrically connected to the electromagnet to selectively reduce or disconnect an electrical power supply to the electromagnet in an emergency stop situation. The safety brake device may be used in a conveyance system such as an elevator system comprising a speed sensor which monitors the speed of the component (e.g. elevator car). If a freefall, over-speed condition, or over-acceleration condition of the component is detected by the speed sensor, the controller will operate to reduce or remove power to the electromagnet. The controller may be in direct communication with such a speed sensor or accelerometer, or signals from the speed sensor and/or accelerometer may be monitored by a separate safety controller that then decides when to control an electrical power supply to the electromagnet. The electromagnet will therefore not produce a magnetic field to counteract the biasing force, and the pad will therefore move from the first to the second position, and the safety brake will therefore be engaged if the elevator is moving or accelerating too fast. The electromagnet may therefore be controlled in an emergency stop mode.
In a set of examples, the safety brake device is reset by moving the component upwards relative to the guide rail. The component is moved upwards such that the safety brake is disengaged and the electromagnet is aligned with the pad. Once aligned, power is restored to the electromagnet by the controller, creating an attractive magnetic force between the electromagnet and pad. This magnetic force is stronger than the biasing force caused by the biasing member, and the pad is therefore pulled away from the guide rail to the first position such that the safety brake device is reset.
In a set of examples, the support comprises a surface arranged to move upwards and downwards relative to the mounting portion, the surface oriented at an acute angle relative to a direction of lateral movement of the pad between the first position and the second position. This arrangement may allow the actuator to “self-reset”. As the surface is at an angle relative to the pad, the support may therefore be wedge shaped in order to provide a vertical support surface on which to connect the springs and guiding rods. To engage the safety brake, the controller will reduce or remove power to the electromagnet such that the biasing force provided by the biasing member pushes the pad to the second position, in contact with the guide rail. Due to the relative downwards motion of the component, the support, biasing member and pad will move upwards, with the support moving along the angled surface. Due to this angle of the surface, the biasing member will be compressed as it moves relatively upwards with the pad. The linkage mechanism will transmit this upwards reaction force to the safety brake, such that the safety brake is engaged.
The system is able to automatically self-reset due to the angled support surface. Once the safety brake is engaged, the component will be brought to a stop and there is no longer any upwards reaction force on the pad. Due to the angled support surface, the electromagnet will displace towards the pad as the electromagnet moves upwards. Therefore, there may be little or no gap between the electromagnet and pad in the second position such that a minimal electrical current may be sufficient for the magnetic force provided by the electromagnet to overcome the biasing force provided by the biasing member, assisting with reset of the actuator.
The safety brake may be mounted to the component independently of the actuator, with the linkage mechanism arranged between them. However, in a set of examples, the mounting portion also mounts the safety brake to the component such that the safety brake device is a single integrated unit. This arrangement is advantageous as the safety brake device is one unit which may be affixed to a component in a single installation step.
In a set of examples, the safety brake comprises a wedge brake. Some suitable wedge brake arrangements include a roller mounted to move relative to a wedge, or one or more wedge-shaped brake pads mounted to move into engagement with a guide rail. Therefore, movement of the linkage mechanism coupled between the wedge brake and the actuator is such that when the mounting portion is moving downwards relative to the guide rail, movement of the pad to the second position creates an upwards reaction force transmitted by the linkage mechanism to move the wedge brake upwards into the braking position. The wedge brake will be moved against the guide rail and the friction between these two surfaces will bring the component to a halt. However, the safety brake may comprise any suitable arrangement for stopping motion of a component via mechanical engagement with a guide rail.
In examples of the present disclosure, the safety brake device may find use in a variety of conveyance systems, such as elevator systems, people conveyors, goods transporters, etc. The component that is moveable along a guide rail may be a platform, a counterweight or a cab for transporting goods or people. In some examples, the conveyance system is an elevator system and the component is an elevator car.
According to some further examples of the present disclosure, there is provided an elevator system comprising an elevator car driven to move along at least one guide rail, and the safety brake device as set out previously, wherein the mounting portion is mounted to the elevator car and the safety brake is arranged to be moveable between the non-braking position where the safety brake is not in engagement with the guide rail and the braking position where the safety brake is engaged with the guide rail. In such examples, the safety brake may be mounted to the elevator car independently of the actuator, or via the mounting portion.
In a set of examples, the elevator system comprises a speed sensor and a safety controller arranged to receive a speed signal from the speed sensor and to selectively reduce or disconnect an electrical power supply to the electromagnet upon detecting an overspeed or over-acceleration condition for the elevator car based on the speed signal. It will be appreciated that acceleration may be determined through processing of the speed signal to produce an acceleration signal e.g. by differentiating the speed signal. In a set of examples, in addition or alternatively, the elevator system comprises an accelerometer, with the safety controller arranged to receive an acceleration signal from the accelerometer, and selectively reduce or disconnect an electrical power supply to the electromagnet upon detecting an over-acceleration condition for the elevator car. Therefore, when the elevator car is travelling at overspeed or over-acceleration, reduction of the power to the electromagnet will reduce the magnetic force applied to the pad. The biasing force will therefore move the pad from the first to the second position, and the safety brake will therefore be actuated to engage with the guide rail, preventing further motion of the elevator car.
According to a second aspect of the present disclosure, there is provided a method of operating a safety brake in a safety brake device, the safety brake moveable between a non-braking position where the safety brake is not in engagement with a guide rail and a braking position where the safety brake is engaged with a guide rail, the safety brake device comprising: an actuator comprising: a mounting portion for mounting the actuator to a component moveable along a guide rail; a pad arranged to be moveable relative to the mounting portion between a first position spaced from the guide rail and a second position in contact with the guide rail, the pad comprising a ferromagnetic material; at least one biasing member configured to apply a biasing force to move the pad from the first position to the second position; and an electromagnet; and a linkage mechanism coupled between the safety brake and the actuator; the method comprising: operating the electromagnet in a normal mode to apply a magnetic field to the pad and thereby create a magnetic force acting against the biasing force to move the pad towards the first position; and operating the electromagnet in an emergency stop mode to reduce or remove the magnetic force acting against the biasing force such that the pad moves to the second position to create an upwards reaction force when the mounting portion is moving downwards relative to the guide rail, the upwards reaction force being transmitted by the linkage mechanism to move the safety brake into the braking position.
In a set of examples, the method further comprises: detecting an overspeed or over-acceleration of the component; and initiating the emergency stop mode by selectively reducing or disconnecting an electrical power supply to the electromagnet.
As mentioned above, such methods may find use in a variety of conveyance systems, but in at least some examples the method is used to operate a safety brake in a safety brake device in an elevator system and the component is an elevator car.
In the elevator system 10 shown in
Mechanical speed governor systems are being replaced in some elevators by electronically-actuated systems. A safety brake device 40 is described herein that is suitable for electronic or electrical control of actuating and resetting the safety brakes 24.
The safety brake device 40 comprises a safety brake 48 which is moveable between a non-braking position where the safety brake 48 is not in engagement with the guide rail 20, and a braking position where the safety brake 48 is engaged with the guide rail 20. The safety brake 48 is illustrated as a wedge-type safety brake comprising an angled “wedge” surface 48b and a roller 48a moveable along the surface 48b from a non-braking position (as seen in
Regardless of the exact form of the safety brake 24, a linkage mechanism 50 is coupled between the safety brake 48 and an actuator 52. The actuator 52 comprises the mounting portion 42, and a pad 54, a spring 56, a support 58, a set of linear roller bearings 60, and an electromagnet 62. The pad 54 is movable between a first position spaced from the guide rail 20 (as seen in
Turning now to
The spring 56 is connected between the pad 54 and the support 58. A guiding rod 70 is arranged through the centre of the spring 56 and is connected to the support 58 and to the pad 54 by nuts 72. The guiding rod 70 is rigid and prevents buckling of the spring 56, as well as preventing the pad 54 from falling. The spring 56 is arranged to connect the centre of the pad 54 to the centre of the support 58 in order to reduce any torque on the spring 56 due to movement of the pad 54 and/or support 58. The pad 54 has a high friction surface 74 which is arranged to contact the guide rail 20 when in the second position.
In this example the pad includes a reset portion 84 that is arranged to form part of the ferromagnetic core 64 inside the electrical coil 66 when the pad 54 is in the first position. This means that the pad 54 completes the magnetic circuit of the electromagnet 62, assisting reset of the safety brake device 40
If a freefall, over-speed, or over-acceleration condition of the elevator car 16 is detected by the governor 22, the controller (seen in
The contact of the pad 54 with the guide rail 20, and in particular, the high-friction surface 74 contacting the guide rail 20, causes the connected support 58 and pad 54 to move upwards relative to the car 16. This movement is shown in
The pad 54, spring 56, support 58 and guiding rod 70 are able to move upwards due to the linear roller bearings 60 which allow motion of the support 58 relative to the mounting portion 42 of the actuator 52 up and down. As the support 58 and pad 54 move upwards due to the upwards reaction force, this upwards reaction force is applied to the linkage mechanism 50 which is connected between the pad 54 and the safety brake 48. The linkage mechanism 50 therefore transmits the upwards reaction force to the roller 48a of the safety brake 48 to move the roller 48a upwards along the inclined surface 48b into the braking position such that it engages the guide rail 20 and prevents further downwards motion of the elevator car 16, as shown in
To reset the safety brake 48 and the actuator 52 of the safety brake device 40, the elevator car 16 is moved upwards with the mounting portion 42 until the electromagnet 62 is aligned with the pad 54, which disengages the safety brake 48. During the reset process, power is restored to the electromagnet 62 by the controller (seen in
A further example of the safety brake device is shown in
The spring 156a and associated guiding rod 170a are arranged to connect the top of the pad 154 to the top of the support 158. The spring 156b and associated guiding rod 170b are correspondingly arranged to connect the bottom of the support 158 to the lower part of the pad 154. This symmetric arrangement of springs and guiding rods ensures a balanced biasing force is provided to the pad 154. When power is removed from the electromagnet 62, the equal biasing forces provided by the two springs 156a, 156b will ensure a linear movement of the pad 154 towards the guide rail 20 for contact in the second position. Advantageously, in this example, the biasing force provided to the pad 154 is more balanced than the example of
In the examples seen in
A third example of the safety brake device is shown in
Further to this, in contrast to the electromagnet 62 in the safety brake devices 40, 140 shown in
The linkage 50 is connected between the safety brake 48 and the actuator 252. When over-speed is detected by the governor 22, the controller (seen in
To reset the safety brake 48 and the actuator 252 of the safety brake device 240, power is restored to the electromagnet 262 by the controller (seen in
A fourth example is shown in
In this example, two springs 356a, 356b and two guiding rods 370a, 370b are used. Each spring 356a, 356b surrounds a corresponding guiding rod 370a, 370b and the springs 356a, 356b and guiding rods 370a, 270b connect the support 358 to the pad 354. Therefore, each guiding rod 370a, 370b prevents each spring 356a, 356b from buckling, as well as preventing the pad 354 from falling.
The upper spring 356a and associated guiding rod 370a are arranged to connect the top of the pad 354 to the top of the support 358 in the actuator 352. The lower spring 356b and associated guiding rod 370b are correspondingly arranged to connect the bottom of the support 358 to the lower part of the pad 354. The electromagnet 262 is coupled to the support 358 between the two springs 356a, 356b and guiding rods 370a, 370b. This symmetric arrangement of springs 356a, 356b, guiding rods 370a, 370b and central electromagnet 362 ensures the forces acting on the pad 354 are balanced. The springs 356a, 356b will provide a biasing force to the pad 354 and the electromagnet 362 provides a magnetic force to the pad 354. The overall force therefore acts through the centre of the pad 354, such that there is no torque on the pad 354. Advantageously, in this example, during reset of the safety brake device 340, the balanced forces provides by the springs 356a, 356b, guiding rods 370a, 370b and electromagnet 362 ensures that reset is more reliable than in a safety brake device where the total force is not acting through the centre of the pad 354.
A fifth example is shown in
The friction between the guide rail 20 and pad 454 when the pad 454 is in the second position, shown in
The pad 454, springs 356a, 356b, support 358 and guiding rods 370a, 370b are able to move upwards due to the linear roller bearings 60 between the support 358 and mounting portion 42 which allow motion up and down relative to the mounting portion 42. The electromagnet 362 is also connected to the support 358, and as such moves with the pad 454 etc. As the pad 454, electromagnet 362 and support 358 move upwards due to the upwards reaction force, this upwards reaction force is applied to the linkage mechanism 150 which is connected to the electromagnet 362 and safety brake 48. The linkage mechanism 150 therefore transmits the upwards reaction force to the safety brake 48 to move the safety brake 48 upwards into the braking position such that it engages and prevents further downwards motion of the elevator car 16, as shown in
Turning now to
The acute angle a of the support 458 and linear roller bearings 160 enables the actuator 452 of the safety brake device 540 to self-reset. The system 540 engages the safety brake 48 using the same method as that shown in
The safety brake device 540 is shown in
Once the safety brake 48 is engaged, the elevator car 16 will be brought to a stop. In order to disengage the safety brake 48, the elevator car 16 is moved upwards. The roller 48a is therefore no longer compressed between the guide rail 20 and wedged surface 48b. The safety brake 48 will therefore move downwards due to gravity, pulling on the linkage 50 which therefore also moves the actuator 452 to its initial position shown in
In any of the examples disclosed above, the linkage 50, 150 may be connected to the support 58, 158, 258, 358, 458 instead of the pad 54, 154, 254, 354 or electromagnet 362. The support 58, 158, 258, 358, 458 moves upwards due to the upwards reaction force when the pad 54, 154, 254, 354, 454 moves from the first to the second position so may transmit the upwards reaction force to the linkage 50, 150, and therefore to the safety brake 48.
In any of the examples disclosed above, the linear roller bearings 60, 160 may be replaced by any suitable bearing parts or a bearing surface, for example a relatively low friction surface interface between the support and the mounting portion. For example, the support may have a low friction surface or surface coating to aid its movement relative to the mounting portion. A lubricant may be used as well or instead of any bearing parts.
In any of the examples disclosed above, the linkage mechanism (50) may take any suitable form for mechanical transmission of the upwards reaction force. Although the linkage mechanism (50) has been illustrated in the form of a bar, it could be a wire, or a series of link members, or a plate, for example.
It will be appreciated by those skilled in the art that the disclosure has been illustrated by describing one or more examples thereof, but is not limited to these examples; many variations and modifications are possible, within the scope of the accompanying claims. For example, the safety brake device may be used in a roped or ropeless elevator system, or another type of conveyance system.
| Number | Date | Country | Kind |
|---|---|---|---|
| 20382884 | Oct 2020 | EP | regional |
| Number | Name | Date | Kind |
|---|---|---|---|
| 11066274 | Khzouz | Jul 2021 | B2 |
| 20150240894 | Piech et al. | Aug 2015 | A1 |
| 20190144240 | Steinhauer et al. | May 2019 | A1 |
| Number | Date | Country |
|---|---|---|
| 102013111385 | Apr 2015 | DE |
| 3677534 | Jul 2020 | EP |
| WO-2005044709 | May 2005 | WO |
| 2017087978 | May 2017 | WO |
| WO-2017098299 | Jun 2017 | WO |
| Entry |
|---|
| European Search Report for Application No. 20382884.3; dated Mar. 18, 2021; 9 Pages. |
| Number | Date | Country | |
|---|---|---|---|
| 20220106164 A1 | Apr 2022 | US |
