Patent Description:
It is known in the art to mount safety brakes onto elevator components moving along guide rails, to bring the elevator component quickly and safely to a stop, especially in an emergency. In many elevator systems the elevator car is hoisted by a tension member with its movement being guided by a pair of 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, "safety gear" or "safety") which is capable of stopping the elevator car from moving downwards, even if the tension member breaks, by gripping a guide rail. Safety brakes may also be installed on the counterweight or other components moving along guide rails.

Electronic Safety Actuators (ESA's) are now commonly used instead of just using mechanical governors to trigger a safety brake. ESA's typically activate a safety brake by dragging a magnet (either a permanent magnet or an electromagnet) against the guide rail, and using the friction to pull up on a linkage attached to the safety brake. The reliance on the friction interaction between a magnet and the guide rail has a number of problems, especially in high-rise elevator systems, as the interaction between the magnet and the guide rail causes wear on the guide rail, and can induce chipping, as well as debris accumulation. Any degradation of guide rail condition is of concern as it affects the safety of the whole elevator system.

There is therefore a need to improve electronic safety actuation of the safety brakes.

<CIT> describes an electromechanical actuator for actuating a brake of a lift installation comprising an energy accumulator, a holding device, a resetting device, and a connector. The actuator is designed such that in a standby state the holding device holds the connector in a standby position against an actuation force applied by the energy accumulator, and that in a release state the holding device does not hold the connector in the standby position and the connector is moved into a release position. During a return phase, the actuator is moved from the tripping state to the tripping state using the resetting device. The holding device is connected to the connector via a toggle lever arrangement, with the toggle lever arrangement having a more extended orientation in the standby state than in the triggered state. <CIT> discloses a safety actuator according to the preamble of claim <NUM>.

<CIT> describes a safety mechanism for an elevator which is activated in response to an electronic signal. The safety mechanism uses a solenoid actuator and an electric motor and gear box assembly to move safety wedges into engagement with a guide rail.

<CIT> describes an electronic safety actuator assembly, where a magnet is vertically moveable relative to the elevator car and an electromagnet is switchable between an energized condition and an un-energized condition, one of which magnetically attracts the magnet to the electromagnet, where repulsion of the magnet moves the safety brake into a braking position.

According to a first aspect of the invention there is provided a frictionless electronic safety actuator for use in an elevator system, in accordance with claim <NUM>.

It will be appreciated that, according to the present disclosure, the frictionless electronic safety actuator provides actuation for a safety brake, without the aid of frictional contact between the electronic safety actuator and the guide rail. This provides the advantage that actuation of the safety brake is not affected by the state of the elevator guide rail, so no debris from the elevator hoistway or dirt from the elevator guide rail can interfere with the actuation of the frictionless electronic safety actuator.

It will furthermore be appreciated that the location of the frictionless electronic safety actuator is no longer restricted by the need for contact with the guide rail, and can be positioned anywhere on an elevator component where the linkage can then actuate the safety brake. Therefore, in some examples no component of the frictionless electronic safety actuator comes into frictional contact with the elevator guide rail.

It will be understood by the skilled person that the connection arrangement can be any form of connection between the magnetic plate and the linkage, and whilst certain examples of types of connection arrangement are disclosed herein, these are by way of example only. The movement of the linkage can be a vertical movement aimed to push or pull the safety brake into engagement with the elevator rail. In other examples the movement of the linkage can be in any direction so as to move the safety brake into a position of engagement with the elevator guide rail.

The connection arrangement is configured translate a horizontal displacement of the magnetic plate to a vertical movement of the linkage. The connection arrangement may be in the form of a scissor mechanism which translates a horizontal movement of the magnetic plate to a vertical movement of the linkage. Such an arrangement can be advantageous in places where there is limited vertical space for placing the frictionless electronic safety actuator relative to a safety brake.

The connection arrangement includes a compression spring arrangement configured to translate a horizontal displacement of the magnetic plate to a vertical movement of the linkage; wherein the compression spring arrangement generates a spring bias to return to a relaxed state which actuates a vertical movement of the linkage to move a safety brake into frictional engagement with an elevator guide rail. The use of a compression spring arrangement means a bias can be introduced, where the spring biases the magnetic plate into a position where the linkage actuates the safety brake when the connection arrangement is free to move. This can be due to the removal of a magnetic force which the electromagnet can selectively operate to keep the magnetic plate in a position where the linkage is not actuated i.e. a normal operating position. When the magnetic field is removed or reversed the magnetic plate can be pulled by the bias of the compression spring arrangement into a position which actuates the linkage. In some examples the compression spring arrangement comprises at least one leaf spring. In some examples the compression spring arrangement comprises a buckling spring.

The connection arrangement includes a plurality of leaf springs connected in series to form a concertina in a vertical direction with one end fixed and one end movable in vertical direction; and a linkage connection point located on the movable end of the concertina. Optionally the plurality of leaf springs can have a relaxed state which biases towards a position which actuates the linkage, and during normal operation the magnetic force between the at least one electromagnet and the magnetic plate can pull the plurality of leaf springs against their bias in a horizontal direction. Optionally the plurality of leaf springs comprises thin metal sheet plates. Such leaf springs may be able to deform easily without exceeding their yield strength but being able to provide adequate spring bias force and displacement distance. It will be appreciated that the use of a plurality of leaf springs allows for a small horizontal deflection to be translated into a larger vertical deflection, which can provide a large actuation distance for the linkage.

In some examples of the first set of examples, of the first set of examples, the vertical movement of the plurality of leaf springs is guided so a first side of the plurality of leaf springs is fixed in the horizontal direction and guided in the vertical direction, and a second side of the plurality of leaf springs is guided in the vertical direction and movable in the horizontal direction; and wherein the second side of the plurality of leaf springs is attached to the magnetic plate, and horizontal movement is determined by the operation of the at least one electromagnet. This fixation helps to prevent losses in vertical movement due to an unbalanced spring, thereby increasing the transfer efficiency of the spring force from the horizontal direction to the vertical direction.

In some examples of the first set of examples, the at least one electromagnet is operable to remove or reverse the magnetic field in order to displace the magnetic plate. It will be appreciated that this can mean a triggering of the frictionless electronic safety actuator. The plurality of leaf springs can be allowed to return to their relaxed state, by reducing the horizontal deflection, wherein the reduction in horizontal direction is translated to a movement in the vertical direction so as to actuate the linkage. This triggered state being the natural state of the springs (either a plurality of leaf spring or any other form of compression spring), has the advantage of making the movement to the triggered position as efficient as possible. In addition, it will be appreciated that this can introduce a failsafe, as if the at least one electromagnet were to lose power the frictionless electronic safety actuator can automatically trigger the safety brakes.

In some examples of the first set of examples, the magnetic plate comprises at least one permanent magnet. By using at least one permanent magnet it will be appreciated that the power requirement for the frictionless electronic safety actuator can be greatly reduced, as continuous power is not required to stop the actuation of the linkage, instead only a small amount of power is required for the release of the magnetic plate. Optionally the attractive magnetic force between the permanent magnet and the electromagnet when no current is running through the electromagnet is greater than the spring force of the plurality of leaf springs.

In the examples where the magnetic plate comprises at least one permanent magnet, the arrangement is similar to that of many traditional ESA systems (albeit with actuation now taking place in a frictionless way). This means that existing ESA layouts can be retained. It will be appreciated that the operation of the at least one electromagnet may also be similar to that of many traditional ESA systems and so may allow for an easy upgrade to a frictionless ESA as disclosed herein.

In some examples of the first set of examples, the at least one electromagnet is operable to produce a magnetic field to repel the magnetic plate. It will be appreciated that when the magnetic plate additionally comprises at least one permanent magnet a magnetic field is required to move the magnetic plate from the normal operating position into a triggered position. This can be aided by the spring bias of the compression spring arrangement, so as to efficiently actuate the linkage.

In some examples of the first set of examples, the at least one electromagnet is operable to produce a magnetic field to reset the magnetic plate; wherein the magnetic plate is moved in the horizontal direction against the bias of the compression spring arrangement. It will be appreciated that such a movement can move the magnetic plate from a triggered position back to the normal operating position. Optionally, the magnetic plate can be kept in place by the magnetic force of the at least one electromagnet, during normal operation.

In the first set of examples the connection arrangement is arranged to translate a horizontal movement of the magnetic plate to a vertical movement of the linkage. Advantageously a small horizontal movement can be translated into a larger vertical movement for the actuation of the linkage. Some configurations of elevator components and their safety brakes may have space constraints which this first example of frictionless electronic safety actuator is more suited to. There are however various alternative connection arrangements which are suitable for use in the frictionless electronic safety actuator. A second set of examples of an implementation of the frictionless electronic safety actuator are hereby given.

According to a second non-claimed set of examples the at least one electromagnet is configured to move the magnetic plate and its attached connection arrangement in a vertical direction to directly displace the linkage in the vertical direction. It will be appreciated that an arrangement such as this can actuate the linkage and activate a safety brake in an uncomplicated way. In this second set of examples the connection arrangement can be relatively simple, with fewer parts which may be causes of error.

In some examples of the second set of examples, a single electromagnet is configured to move the magnetic plate in a vertical direction to vertically displace the linkage.

In some examples of the second set of examples, a pair of electromagnets are positioned vertically displaced so as to selectively produce magnetic forces to displace the magnetic plate vertically between the two electromagnets so as to actuate the linkage.

It will be appreciated, that an electromagnet may be configured to push the magnetic plate upwards in a vertical direction to vertically displace the linkage, and/or an electromagnet may be configured to push the magnetic plate upwards in a vertical direction to vertically displace the linkage. It will also be appreciated that the use of a pair of magnets used to displace the magnetic plate between them will require smaller electromagnets, and may require less power than a single electromagnet. The combination of magnetic fields produced by a pair of electromagnets can be more easily tuned to control the movement of the magnetic plate, and allow for more efficient actuation of the linkage.

In some examples of the second set of examples, the magnetic plate is displaced towards a stop, wherein the stop is resiliently mounted. A resilient mounting of the stop can allow for over-travel in the displacement of the magnetic plate, which can allow for larger tolerances in the connection of the linkage to the safety brake, where variable actuation distances can be absorbed. The stop can be a magnetic plate, or a permanent magnet, or an electromagnet.

In some examples of the second set of examples, the resilient mounting of the stop is arranged to relax to assist with reset of the magnetic plate. Optionally, the resilient mounting can be a spring.

In some examples of the second set of examples, the at least one electromagnet is operable to produce a magnetic field to displace the magnetic plate upwards in the vertical direction, i.e. to actuate the linkage. It will be appreciated that the displacement of the magnetic plate can be caused by various combinations of magnetic fields, depending on the number of electromagnets used in the frictionless electronic safety actuator. Where a single electromagnet is used at the bottom a repulsive magnetic field can be produced to repel the magnetic plate upwards. Where a single electromagnet is used at the top an attractive magnetic field can be produced to attract the magnetic plate upwards. Where a pair of electromagnets are used a combination of fields can be produced to produce the upwards movement.

In some examples of the second set of examples, the at least one electromagnet is operable to remove or reverse the magnetic field to displace the magnetic plate. It will be appreciated that the magnetic plate can fall back down to the normal operating position under the force of gravity. This means the reset of the frictionless electronic safety actuator is easily performed without external influence. The magnetic plate can be actively displaced downwards by the operation of the at least one electromagnet, which aids the natural movement of the magnetic plate with gravity.

In some examples of the second set of examples, the magnetic plate is a permanent magnet. A permanent magnet can create a larger magnetic field, an easier interaction between the magnetic plate and the at least one electromagnet. As such less power may be required for the at least one electromagnet to move the magnetic plate into the triggered position.

Certain preferred examples of this disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which:.

<FIG> shows an elevator system, generally indicated at <NUM>. The elevator system <NUM> includes cables or belts <NUM>, a car frame <NUM>, an elevator car <NUM>, roller guides <NUM>, guide rails <NUM>, a governor <NUM>, and a pair of safety brakes <NUM> mounted on the elevator car <NUM>. The governor <NUM> is mechanically coupled to actuate the safety brakes <NUM> by linkages <NUM>, levers <NUM>, and lift rods <NUM>. The governor <NUM> includes a governor sheave <NUM>, rope loop <NUM>, and a tensioning sheave <NUM>. The cables <NUM> are connected to the car frame <NUM> and a counterweight (not shown) inside a hoistway. The elevator car <NUM>, which is attached to the car frame <NUM>, moves up and down the hoistway by a force transmitted through the cables or belts <NUM> to the car frame <NUM> by an elevator drive (not shown) commonly located in a machine room at the top of the hoistway. The roller guides <NUM> are attached to the car frame <NUM> to guide the elevator car <NUM> up and down the hoistway along the guide rails <NUM>. The governor sheave <NUM> is mounted at an upper end of the hoistway. The rope loop <NUM> is wrapped partially around the governor sheave <NUM> and partially around the tensioning sheave <NUM> (located in this example at a bottom end of the hoistway). The rope loop <NUM> is also connected to the elevator car <NUM> at the lever <NUM>, ensuring that the angular velocity of the governor sheave <NUM> is directly related to the speed of the elevator car <NUM>.

In the elevator system <NUM> shown in <FIG>, the governor <NUM>, a machine brake (not shown) located in the machine room, and the safety brakes <NUM> act to stop the elevator car <NUM> if it exceeds a set speed as it travels inside the hoistway. If the elevator car <NUM> reaches an over-speed condition, the governor <NUM> is triggered initially to engage a switch, which in turn cuts power to the elevator drive and drops the machine brake to arrest movement of the drive sheave (not shown) and thereby arrest movement of elevator car <NUM>. If, however, the elevator car <NUM> continues to experience an overspeed condition, the governor <NUM> may then act to trigger the safety brakes <NUM> to arrest movement of the elevator car <NUM> (i.e. an emergency stop). In addition to engaging a switch to drop the machine brake, the governor <NUM> also releases a clutching device that grips the governor rope <NUM>. The governor rope <NUM> is connected to the safety brakes <NUM> through mechanical linkages <NUM>, levers <NUM>, and lift rods <NUM>. As the elevator car <NUM> continues its descent, the governor rope <NUM>, which is now prevented from moving by the actuated governor <NUM>, pulls on the operating levers <NUM>. The operating levers <NUM> actuate the safety brakes <NUM> by moving the linkages <NUM> connected to the lift rods <NUM>, and the lift rods <NUM> cause the safety brakes <NUM> to engage the guide rails <NUM> to bring the elevator car <NUM> to a stop.

It will be appreciated that, whilst a roped elevator is described here, the examples of an electronic safety actuator described here will work equally well with a ropeless elevator system e.g. hydraulic systems and systems with linear motors.

Whilst mechanical speed governor systems are still in use in many elevator systems, others are now implementing electronically actuated systems to trigger the emergency safety brakes <NUM>. Most of these electronically actuated systems utilize use friction between a magnet and the guide rail <NUM> to then mechanically actuate a linkage to engage the safety brakes <NUM>. Examples of an electronic safety actuator are disclosed herein which do not utilize friction against the guide rail <NUM> to actuate the safety brakes <NUM>.

<FIG> shows a first example of a frictionless electronic safety actuator <NUM> during normal elevator operation, and <FIG> shows the first example of the frictionless electronic safety actuator <NUM> in a triggered position. <FIG> shows the triggered frictionless electronic safety actuator <NUM> situated above a safety brake <NUM> in a tripped position. The frictionless electronic safety actuator <NUM> includes at least one electromagnet <NUM> and a magnetic (e.g. steel) plate <NUM>. The magnetic plate <NUM> is attached to a connection arrangement <NUM> that includes a plurality of leaf springs <NUM> connected in series to form a concertina <NUM> with a fixed side <NUM> with fixation holes <NUM>, a movable side <NUM>, a fixed bottom plate <NUM>, and a moveable top plate <NUM> with a linkage connecting point <NUM>.

In the example shown in <FIG> and <FIG>, the plurality of leaf springs <NUM> are assembled together in the form of a plurality of elliptic leaf springs connected together in series at their apices to form a concertina <NUM>, where a first side of each leaf spring <NUM> is fixed on the horizontal axis, but movable on the vertical axis, and a second side, opposite to the first side, is movable on both the horizontal and vertical axes. The first side of each leaf spring <NUM> is connected to the fixed side <NUM> of the connection arrangement <NUM> via a guide (not shown) to allow movement in the vertical direction. This fixed side <NUM> is configured to be attached to an elevator component, i.e. an elevator car <NUM> or a counterweight, via the fixation holes <NUM>. The second side of each leaf spring <NUM> is connected via a guide (not shown) to the movable side <NUM> of the connection arrangement <NUM>, which is attached to the magnetic plate <NUM>. In some examples the magnetic plate <NUM> is a steel plate. The concertina <NUM> of leaf springs <NUM> is also attached to the fixed bottom plate <NUM> and the moveable top plate <NUM>, which both extend horizontally between the movable side <NUM> and the fixed side <NUM>. The fixed bottom plate <NUM> is fixed relative to the fixed side <NUM>, and the top plate <NUM> moves vertically with the movement of the plurality of leaf springs <NUM>. A linkage <NUM> (not shown in <FIG>) is connected to the top plate <NUM> at a linkage connecting point <NUM>. The linkage <NUM> connects the frictionless electronic safety actuator <NUM> to a safety brake <NUM> e.g. the safety brake <NUM> mounted below the electronic safety actuator <NUM> as shown in <FIG>.

The plurality of leaf springs <NUM> are designed to deform easily without exceeding their yield strength, whilst still being able to provide the required actuation distance and a spring force capable of actuating the linkage <NUM>. In some examples the plurality of leaf springs <NUM> comprise thin metal sheet plates. Various alternative compression spring arrangements may be contemplated, such as a buckling spring instead of the concertina of leaf springs. In some examples a single leaf spring may be used.

The at least one electromagnet <NUM> is positioned relative to the magnetic plate <NUM> such that, when the at least one electromagnet <NUM> is operated, the produced magnetic field acts on the magnetic plate <NUM>. In the example of <FIG> and <FIG>, the electromagnet <NUM> is positioned horizontally adjacent to the magnetic plate <NUM>. The electromagnet <NUM> is illustrated as having an E-shaped core with a pair of coils, but of course it may take any suitable form e.g. a straight core with a single coil or more than two coils.

<FIG> shows the frictionless electronic safety actuator <NUM> during normal elevator operation. In this example the electromagnet <NUM> is operated to produce a magnetic field which acts upon the magnetic plate <NUM> with a horizontal magnetic force to pull the moveable side <NUM> of the connection arrangement <NUM> towards the electromagnet <NUM> and hence deflect the second side of the concertina <NUM> of the plurality of leaf springs <NUM> in a horizontal direction. The electromagnet <NUM> acts to pull the magnetic plate <NUM> and the moveable side of the concertina <NUM> of the plurality of leaf springs <NUM> horizontally against the force of the plurality of leaf springs <NUM>, and keep the concertina <NUM> of the plurality of leaf springs <NUM> in this position during normal operation of the elevator, as shown by the force arrows. As the leaf springs <NUM> are attached together at their apices in a concertina type arrangement, this horizontal pull causes a combinatory effect with the compression of the plurality of leaf springs <NUM> in the vertical direction.

<FIG> shows the frictionless electronic safety actuator <NUM> in a tripped position, which can be used to actuate the safety brake <NUM> (seen in <FIG>). In this example the electromagnet <NUM> is operated to remove the magnetic field acting upon the magnetic plate <NUM>, so as to allow the moveable side <NUM> of the connection arrangement <NUM> to be pulled away from the electromagnet <NUM> by the concertina <NUM> of the plurality of leaf springs <NUM> exerting a vertical force to recover to their relaxed state, thus reducing their horizontal deflection. This horizontal movement of the magnetic plate <NUM> is shown by the arrows. This produces a vertical movement in the top plate <NUM>, which in turn moves the linkage connecting point <NUM> so that a linkage <NUM> (not shown in <FIG>) is pulled upwards as to actuate the safety brake <NUM>.

In this example the electromagnet <NUM> produces an attractive force upon the magnetic plate <NUM> whilst the elevator is in normal operation (<FIG>). When the safety brakes <NUM> need to be engaged, the electromagnet <NUM> stops producing the attractive force and the force of the plurality of leaf springs <NUM> actuates the linkage pulling on the safety brake <NUM>. This can act as a failsafe in case of a loss of power, as when the electromagnet <NUM> loses power, the safety brake <NUM> will be actuated automatically.

In some examples the at least one electromagnet <NUM> is operated to actively repel the magnetic plate <NUM>, providing additional force to the force of the plurality of leaf springs <NUM> to return to their relaxed state. This can speed up the process of actuating the safety brake <NUM>.

To reset the frictionless electronic safety actuator <NUM> the at least one electromagnet <NUM> is operated to produce a magnetic force to displace the magnetic plate <NUM> horizontally back to its original position, against the bias of the concertina <NUM> of the plurality of leaf springs <NUM>.

In the example shown in <FIG> the electromagnet <NUM> is operated to produce an attractive magnetic field which acts on the magnetic plate <NUM> to pull the magnetic plate <NUM>, back to its normal operating position. This pulls the plurality of leaf springs <NUM> into a deflected position.

<FIG> shows an example of the frictionless electronic safety actuator <NUM> situated above a safety brake <NUM> in a tripped position. A linkage <NUM> is shown attached at one end to the top plate <NUM> at the linkage connection point <NUM>, and at the other end to the safety brake <NUM>. The linkage has actuated the safety brake <NUM>. The connection arrangement <NUM> is illustrated which comprises the plurality of leaf springs <NUM>, fixed side <NUM> with fixation holes <NUM>, movable side <NUM>, fixed bottom plate <NUM>, top plate <NUM> and linkage connecting point <NUM>. In this example the magnetic (e.g. steel) plate <NUM> also comprises at least one permanent magnet <NUM>.

In the example shown in <FIG>, the magnetic plate <NUM> comprises at least one permanent magnet <NUM>. The permanent magnets <NUM> act to aid the attraction of the magnetic plate <NUM> to the at least one electromagnet <NUM>. In this example constant current is not required in the at least one electromagnet <NUM> during normal operation of the elevator, and the at least one electromagnet <NUM> is only operated to provide a force to help the plurality of leaf springs <NUM> return to their relaxed state, and actuate the safety brake <NUM>.

In the example of <FIG>, to reset the frictionless electronic safety actuator <NUM> the electromagnet <NUM> is switched off to allow the magnetic plate <NUM> to displace horizontally back to its normal operating position. In some examples the electromagnet <NUM> is operated to produce a force to displace the magnetic plate <NUM> horizontally back to its original position, to aid with force provided by the at least one permanent magnet <NUM>. Once the magnetic plate <NUM> has returned to its normal operating position the electromagnet <NUM> can be turned off. In this example minimal power is required to operate the frictionless electronic safety actuator <NUM>, which improves operational efficiency of the system.

<FIG>, <FIG> and <FIG> show a second non-claimed example of a frictionless electronic safety actuator <NUM>. The frictionless electronic safety actuator <NUM> comprises a first magnetic plate <NUM>, a second magnetic plate <NUM>, a stop <NUM>, and a spring <NUM>, located within a housing <NUM>. A connection arrangement <NUM> connects the second magnetic plate <NUM> to a linkage <NUM> which is configured to actuate a safety brake <NUM>. The connection arrangement <NUM> may be any form of connection which allows the movement of the second magnetic plate <NUM> to actuate the linkage <NUM>. In this example the connection arrangement <NUM> is a pin.

In an example the first magnetic plate <NUM> is an electromagnet. In another example the stop <NUM> is an electromagnet. In another example both the first magnetic plate <NUM> and the stop <NUM> are electromagnets. The electromagnet(s) may take any suitable form e.g. a straight core with a single coil or more than one coil. The electromagnet(s) <NUM>, <NUM> are positioned so as to act upon the second magnetic plate <NUM>, and move the second magnetic plate <NUM> from a rest position during normal operation as seen in <FIG>, to an actuated position vertically displaced upwards from the rest position as shown in <FIG>. The second magnetic plate <NUM> can be made of a ferrous material, possible including one or more permanent magnets, or the second magnetic plate <NUM> can be a permanent magnet.

Whilst in some examples the stop <NUM> is an electromagnet, it can be any form of physical stop. In some examples the stop <NUM> is a permanent magnet. In some examples the stop is resiliently mounted, preferably so that the resilient mounting can assist with the reset of the magnetic plate. In the example shown in <FIG>, <FIG> and <FIG> the resilient mounting is a spring <NUM>, however other types of resilient mounting may also be suitable, e.g. an actuator, a hydraulic ram, a pneumatic ram etc..

In the example shown in <FIG>, <FIG>, and <FIG>, the first magnetic plate <NUM> is located at the bottom of the housing <NUM> and during normal operation of the elevator the second magnetic plate <NUM> rests above the first magnetic plate <NUM>. The stop <NUM> is attached to the top of the housing <NUM> via a spring <NUM>.

When the frictionless electronic safety actuator <NUM> activates, the electromagnet(s) are operable to produce a force which moves the second magnetic plate <NUM>, from its resting position as shown in <FIG>, upwards towards the stop <NUM>. This movement actuates the linkage <NUM>, which pulls the safety brake <NUM>, as shown in <FIG>. The movement is then absorbed by a compression of the spring <NUM>, as shown in <FIG>. The stop <NUM> restricts the upwards movement of the second magnetic plate <NUM>.

The use of the spring <NUM> allows for a shortened distance between the first magnetic plate <NUM> and stop <NUM>, with space for large actuation distances to be absorbed by the compression of the spring <NUM>, when the second magnetic plate <NUM> is pushed upwards by the electromagnet of the first magnetic plate <NUM>. The spring <NUM> can also absorb some of the force of the movement of the second magnetic plate <NUM>, preventing damage of the stop <NUM> and the second magnetic plate <NUM>. It also aids with reset. Whilst a spring <NUM> is discussed with reference to this example, it will be appreciated by a person skilled in the art that various types of resilient mountings may be suitable.

In the example, where both the first magnetic plate <NUM> and the stop <NUM> are electromagnets, the first magnetic plate <NUM> can be operated to repel the magnetic plate <NUM>, and the stop <NUM> can be operated to attract the magnetic plate <NUM>, increasing the efficiency of the actuation of the safety brake <NUM>. In this example each electromagnet requires less power than a single electromagnet would require.

In the situation where the first magnetic plate <NUM> is an electromagnet, the stop <NUM> can be a permanent magnet, configured to attract the second magnetic plate <NUM>. The magnetic attraction between the second magnetic plate <NUM> and the stop <NUM> can help prevent the second magnetic plate <NUM> from shifting downwards with a pull from the safety brake <NUM>, when the safety brake <NUM> exerts a frictional force against the guide rail <NUM>.

In some examples no power is needed during normal operation, as the second magnetic plate <NUM> is kept in place by its own weight. Advantages for this include improved energy efficiency. In an additional example, the natural magnetic force between the first magnetic plate <NUM> and the second magnetic plate <NUM> provide additional force to keep the second magnetic plate <NUM> in place, even when the electromagnet of the first magnetic plate <NUM> is not powered.

In an example, the electromagnet of the first magnetic plate <NUM> can be operable to produce a magnetic field to keep the second magnetic plate <NUM> in place during normal operation. This prevents any abnormal movement of the elevator car <NUM> from moving the second magnetic plate <NUM> in a way which could accidentally trigger the safety brake <NUM>.

In the examples shown in <FIG>, <FIG> and <FIG>, to reset the frictionless electronic safety actuator <NUM> from the triggered state as seen in <FIG>, back to the position as in <FIG> during normal operation, the electromagnet(s) are operated to produce a reversed magnetic field to attract the second magnetic plate <NUM> back into its normal operating position. The force of the spring <NUM> can aid with this movement, assisting gravity.

The frictionless electronic safety actuator <NUM>, <NUM> is fixed to the elevator car <NUM> and is positioned relative to the safety brake <NUM> such that the linkage can actuate the safety brake <NUM>. The frictionless electronic safety actuator <NUM>, <NUM> is positioned to make no direct contact with the elevator rail <NUM>.

It will be appreciated by those skilled in the art that many forms of linkage <NUM> between the frictionless electronic safety actuator <NUM>, <NUM> and the safety brake <NUM> would be suitable for actuating the safety brake <NUM> based on the movement of the frictionless electronic safety actuator <NUM>, <NUM>. Additionally a variety of types of safety brakes <NUM> are suitable for actuation by a linkage <NUM> in this manner, e.g. a safety brake <NUM> using a wedge or a roller. In the examples shown the safety brake <NUM> is positioned below the frictionless electronic safety actuator <NUM>, <NUM>, however it will be appreciated that other configurations would also be possible, for example, the frictionless electronic safety actuator <NUM>, <NUM> may even be positioned to one side of or below the safety brake <NUM>, e.g. depending on the linkage used.

The above described examples have a number of advantages over traditional electronic safety actuators. The actuation of the safety brake has no dependence on guide rail <NUM> condition, or the speed of the elevator car. Additionally the response time to braking will be improved as actuation is not dependent on a friction force between the electronic safety actuator and the guide rail <NUM>. Movement of the car will also not affect the actuation of the safety brakes, as the actuation of the safety brakes is fully independent of any interaction between the elevator car <NUM> and the guide rails <NUM>. This can improve the safety of the whole elevator system. The frictionless electronic safety actuator may also have the advantage of not damaging the guide rail.

Claim 1:
A frictionless electronic safety actuator (<NUM>) for use in an elevator system, comprising:
at least one electromagnet (<NUM>), and a magnetic plate (<NUM>) attached to a connection arrangement (<NUM>);
wherein the connection arrangement (<NUM>) is configured to connect the magnetic plate (<NUM>) to a linkage (<NUM>) that is actuatable so as to move a safety brake (<NUM>) into frictional engagement with an elevator guide rail (<NUM>);
wherein the at least one electromagnet (<NUM>) is operable to selectively produce a magnetic force which acts upon the magnetic plate (<NUM>) to displace the magnetic plate (<NUM>) and thereby move the connection arrangement (<NUM>) to actuate the linkage (<NUM>) without the magnetic plate (<NUM>) coming into frictional engagement with the elevator guide rail (<NUM>);
wherein the connection arrangement (<NUM>) includes a compression spring arrangement (<NUM>) configured to translate a horizontal displacement of the magnetic plate (<NUM>) to a vertical movement of the linkage (<NUM>); and
wherein the compression spring arrangement (<NUM>) generates a spring bias to return to a relaxed state which actuates a vertical movement of the linkage (<NUM>) to move a safety brake (<NUM>) into frictional engagement with an elevator guide rail (<NUM>); and characterized in that:
the connection arrangement (<NUM>) includes a plurality of leaf springs (<NUM>) connected in series to form a concertina (<NUM>) in a vertical direction with one end fixed and one end movable in vertical direction; and a linkage connection point (<NUM>) located on the movable end of the concertina (<NUM>).