Electronic safety actuator and method for condition or state detection

Abstract

An electronic safety actuator (1) for an elevator safety brake comprises a first solenoid (2), a magnet (3) movable by the first solenoid (2) between a first position adjacent to the first solenoid (2) and a second position remote from the first solenoid (2), a second solenoid (6), and a detector (8). The detector (8) is arranged to apply an electrical signal to one of the first solenoid (2) and the second solenoid (6), and detect an electrical signal induced in the other of the first solenoid (2) and the second solenoid (6) as a result of the applied electrical signal. A method of detecting a condition or state of the first solenoid (2) or the magnet (3) is also provided.

Description

Technical Field

[0001] The present disclosure relates to an electronic safety actuator for an elevator safety brake coil, and a method of detecting a condition or state of a first solenoid or magnet of the electronic safety actuator. Background Art

[0002] Elevator safety brakes are usually mounted on the frame or counterweight of the elevator car and engage with the track mounted to the wall of the hoistway to provide friction and stop the car or counterweight. Mechanical safety actuators are actuated by mechanical linkages, which are triggered by governor devices, etc. An alternative to mechanical safety actuators is to use electronic safety actuators, which actuate the brakes electrically and therefore do not need to be mechanically connected to the governor by mechanical linkages. In the case of electronic safety actuators, these are usually actuated (i.e., when braking is required) by electrical components (such as solenoids). For example, when an overspeed event and / or an over-acceleration event is detected, the controller sends an electrical signal to cause the solenoid to release the actuator assembly that engages the safety brake. In one possible arrangement, the actuator assembly is a magnet that can engage with the guide rail to generate friction, which pulls a connecting rod, which in turn pulls a safety wedge or a safety roller into contact with the guide rail. Such safety wedges or safety rollers automatically engage upon contact with the rails and provide a braking force to stop the elevator car.

[0003] It will be appreciated that the solenoid may be used to actively drive a component (e.g. a magnet) towards the guide track in order to engage the brake (i.e. the solenoid applies a repulsive force), or it may be that the solenoid holds the component (i.e. the magnet) in position during normal (non-braking) operation (i.e. the solenoid applies an attractive force), and that as soon as the solenoid is deactivated the component naturally engages the guide track (either through its own magnetism or under the force of a separate biasing member such as a spring).

[0004] Whichever arrangement is used, it is usually convenient that a power failure causes release of the assembly so that, for safety reasons, the power failure will cause the brake to engage.

[0005] It may also be advantageous to monitor the state of the actuator, i.e., whether it is engaged (causing engagement of the brake) or disengaged (not causing engagement of the brake). Such monitoring may be desirable in order to simply confirm the position of the actuator before and / or after intentional actuation, or to detect possible accidental engagement of the actuator. Such actuator engagement will of course cause engagement of the corresponding safety brake.

[0006] It is known to monitor the health of the solenoid of an electronic safety actuator by triggering and resetting the actuator. This is essentially a test run of the system, which involves pushing a permanent magnet from the electromagnet to a position in contact with the track and then back to the electromagnet. One disadvantage of this test process is that it subjects the components of the electronic safety actuator to high stresses due to the impacts that occur, causing wear on the system. The detection (or confirmation) of the position of the magnet is achieved by a mechanical switch that is pressed when the magnet is in the retracted state. The triggering and resetting process also causes wear on the mechanical switch. Summary of the invention

[0007] According to a first aspect of the present disclosure, there is provided an electronic safety actuator for an elevator safety brake, comprising:

[0008] a first solenoid;

[0009] a magnet movable by the first solenoid between a first position adjacent to the first solenoid and a second position distal to the first solenoid;

[0010] a second solenoid; and

[0011] A detector is arranged to apply an electrical signal to one of the first solenoid and the second solenoid and detect an electrical signal induced in the other of the first solenoid and the second solenoid as a result of the applied electrical signal.

[0012] According to a second aspect of the present disclosure, there is provided a method of detecting a condition or state of a first solenoid or a magnet of an electronic safety actuator for an elevator safety brake, the magnet being movable by the first solenoid between a first position adjacent to the first solenoid and a second position remote from the first solenoid, the method comprising:

[0013] applying an electrical signal to the first solenoid or the second solenoid;

[0014] detecting an electrical signal induced in the other of the first solenoid and the second solenoid as a result of the applied electrical signal; and

[0015] The condition or state is determined based on the detected electrical signal.

[0016] By providing a second solenoid and a detector, an electrical signal can be applied to one of the solenoids so as to induce an electrical signal in the other solenoid, which electrical signal can then be detected. The detected electrical signal can provide useful information, for example relating to the wear of the first solenoid and / or the position of the magnet relative to the first solenoid. This allows, for example, the electronic safety actuator to be tested for wear to be measured without the need to deploy the magnet against a guide rail. Therefore, this increases the safety and life of the electronic safety actuator, because during such deployment, there is reduced wear due to various impacts.

[0017] The magnet may be a permanent magnet.

[0018] In some examples, the detector is further arranged to determine the condition or state of the first solenoid or magnet by comparing the detected electrical signal with at least one reference value. The reference value may be calculated, predetermined, or measured, for example, in an initial calibration measurement or a series of measurements. The reference value may be an expected electrical signal or a baseline electrical signal, such as a signal that would be expected based on a new, unworn, undamaged coil. Alternatively, the detected electrical signal may be compared with the applied electrical signal, for example in order to determine the ratio between the two signals. In such a case, one of the signals (or an amplified version of one of the signals) may be used as a reference value (to which the other signal is compared).

[0019] Some examples include determining the position of the magnet, optionally detecting whether the magnet is in a first position or in a second position. Some examples include determining that the magnet is in a first position when the detected electrical signal is different from a reference value (i.e., when the detected electrical signal is greater than or less than the reference value). Some examples include determining that the magnet is in a first position when the detected electrical signal is within 50%, 30%, 20%, or even 10% of the reference value. Some examples include determining that the magnet is in a second position when the detected electrical signal is 50%, 75%, 80%, or even 90% lower than the reference value. Thus, some examples include comparing the detected electrical signal to a (first and / or second) threshold value, wherein the threshold value is calculated based on the reference value. For example, a first threshold value (e.g., 50%, 70%, 80%, or even 90% of the reference value) may be used, above which the magnet is determined to be in a first position. A second threshold value (eg 50%, 35%, 30%, 20% or even 10% of the reference value) may also be used, below which the magnet is determined to be in the second position. In some examples, the detector may be arranged to carry out some or all of these steps.

[0020] Some examples may also include detecting whether the magnet is in an intermediate position between the first position and the second position. The magnet will typically be in the first position or in the second position due to its magnetic properties, however, it may be in an intermediate position, for example, if there is an obstacle (such as a foreign object) between the magnet and the first solenoid or the guide track that prevents it from fully moving to the first / second position. In the case of using a first threshold and a second threshold, it can be determined that the magnet is in an intermediate position when the detected electrical signal is between the first threshold and the second threshold. In other examples, additional ranges corresponding to intermediate positions may be defined between the first threshold and the second threshold.

[0021] For example, based on a known or experimentally determined relationship between the two coils, a signal applied to one coil may be expected to induce a certain signal in the other coil. For example, an expected value may be determined when the magnet is in a first position, a second position, and one or more intermediate positions. The relationship may, for example, depend on the ratio of the number of turns in the first coil to the number of turns in the second coil and / or depend on the magnetic permeability or magnetic resistance of the material inside the coil. Any deviation from the expected signal may then be determined as being due to a change in the relationship. This may be due to wear in the coil, for example, due to the loss of the effect of the turns in the coil caused by a short circuit between adjacent turns. Alternatively, this may be due to a change in the magnetic circuit through the coil, such as a change in magnetic resistance caused by the introduction (or increase) of an air gap (which is due to the position of the magnet). Coil degradation due to a short circuit is the result of wear (e.g., repeated actuation or high temperature). The change in the magnetic circuit may result from the movement of the magnet between the first position and the second position.

[0022] In some examples, a comparison between the detected electrical signal and a reference value is used to detect wear in the first solenoid. For example, where the detected electrical signal is slightly different from the reference value, this may indicate that wear has occurred in the first solenoid. In some examples, a wear value may be calculated, for example, based on the magnitude of the difference between the detected electrical signal and a threshold or in proportion thereto, thereby indicating the severity of wear on the first solenoid. More wear results in more shorts between adjacent turns and thus reduces the turns ratio between the two coils. This in turn changes the relationship between the two coils and changes the detected signal accordingly. Whether the detected signal is higher or lower as a result of wear will depend on whether the applied signal is in the coil with more turns or in the coil with fewer turns. It will also depend on whether voltage or current is being measured. For example, a small voltage applied to a smaller secondary coil (fewer turns) will cause a large voltage to be detected in a larger primary coil (more turns). Wear in the primary coil will cause a voltage to be detected in the primary coil that is less than expected. On the other hand, a large voltage applied to a larger primary coil (more turns) will cause a small voltage to be detected in a smaller secondary coil (fewer turns). Wear in the primary coil will cause a larger than expected voltage in the secondary coil. Similarly, a large current applied to a smaller secondary coil (fewer turns) will cause a small current to be detected in the larger primary coil (more turns). Wear in the primary coil will cause a larger than expected current in the primary coil.

[0023] It will be appreciated that the second solenoid may be separate from the first solenoid, i.e., such that an electrical signal may be applied by the detector to one of the first and second solenoids without being directly applied to the other of the solenoids. In other words, the first solenoid includes a first end and a second end (to which the electrical signal may be applied), and the second solenoid includes a third end and a fourth end (to which the electrical signal may also be applied). These separate ends allow voltage or current to be applied independently to the first or second solenoid. Each end may include a corresponding connector.

[0024] The second solenoid may be referred to as a monitoring solenoid.In this document, the terms solenoid and coil are used interchangeably to refer to one or more turns (or loops) of an electrical conductor, such as a spiral.

[0025] In some examples, the number of turns of the second solenoid is less than the number of turns of the first solenoid, optionally less than half the number of turns of the first solenoid, further optionally less than one quarter of the number of turns of the first solenoid. In some embodiments, the number of turns of the second solenoid may be less than 100 turns, optionally less than 50 turns, further optionally less than 20 turns, further optionally less than 10 turns, and further optionally less than 5 turns. The first solenoid has a large number of turns so as to be able to provide a strong magnetic field for repelling the magnet towards the guide track (or for attracting the magnet back from the guide track in the case of a reset). The second solenoid is provided for monitoring purposes and therefore does not need to provide a strong magnetic field and therefore has fewer turns. The number of turns in the first solenoid may be selected to provide a desired magnetic field strength for the safety actuator to function. The number of turns in the second solenoid may be selected to provide a convenient relationship between the signals in the first solenoid and the second solenoid for ease of measurement.

[0026] This difference in the number of turns is advantageous because it allows a small electrical signal introduced into one of the solenoids to induce a larger electrical signal in the other solenoid, so that only the small electrical signal need be applied in order to produce the resulting induced electrical signal (which is large enough to be reliably measurable). For example, the ratio of the applied electrical signal to the induced electrical signal may be equal to or proportional to the ratio of the number of turns in the solenoid to which the electrical signal is applied to the number of turns in the solenoid in which the electrical signal is induced. This use of relatively small electrical signals reduces the cost of applying such electrical signals, for example, for testing or measurement purposes. Large signals require larger electronic components, which are more expensive. Therefore, processing smaller signals is generally desirable.

[0027] In some examples, the detector is arranged to detect a voltage across a first solenoid or across a second solenoid. For example, the detector may be arranged to apply an electrical signal to the second solenoid and measure the voltage induced in the first solenoid as a result. In the event that the second solenoid has fewer turns than the first solenoid, the voltage induced in the first solenoid will be greater than the voltage applied to the second solenoid, so advantageously only a relatively small voltage is required to produce a large voltage in the measured solenoid. The small applied voltage is easy to generate by inexpensive electronics. The large detected voltage provides a high degree of sensitivity with which to measure the health or state of the first solenoid and / or the magnet).

[0028] In some examples, the detector is arranged to detect a current across a first solenoid or across a second solenoid. For example, the detector may be arranged to apply an electrical signal to a first solenoid and measure the current induced in the second solenoid as a result. In the case where the second solenoid has fewer turns than the first solenoid, the current induced in the second solenoid will be greater than the current applied to the first solenoid, so advantageously only a relatively small applied current is required to produce a large detected current in the measured solenoid. The advantages of inexpensive drive circuits and high detector sensitivity also apply here.

[0029] In some examples, the first solenoid and the second solenoid are coaxial. This allows the two solenoids to be conveniently wound onto the same bobbin or core. This is convenient from a manufacturing and / or assembly perspective because only a single bobbin or core is required. In addition, the second solenoid can be easily added to the manufacturing process or even retrofitted to an existing actuator without difficulty. The first solenoid and the second solenoid can be made of the same material. The first solenoid and / or the second solenoid can be made of copper. The copper can be coated with a non-conductive coating (such as a resin) to insulate one turn from an adjacent turn. As noted above, such coatings may fail over time (e.g. due to high operating temperatures), resulting in a short circuit and an effective reduction in the number of turns in the solenoid.

[0030] In some examples, the electrical signal is applied in the same direction as the brake signal (which will cause the electronic safety actuator to move the magnet from the first position to the second position). The amplitude of the electrical signal used for measurement is preferably not large enough to move the magnet from the first position to the second position. An advantage of this arrangement is that the electrical signal applied to or induced in the first solenoid should not cause actuation of the safety actuator (and therefore should not cause engagement of the brake). In other words, if the magnet is in the first position when the electrical signal is applied (i.e., a measurement is taken), then the magnet should remain in the first position after the measurement or detection has been completed.

[0031] As discussed above, the first solenoid may be arranged to apply a current to repel the magnet from the first position to the second position, or the first solenoid may be continuously supplied with current so as to hold the magnet in the first position so that it is released to the second position as soon as the current drops. In the former case, the default value is that no current flows through the first solenoid, but the detector supplies an electrical signal (which directly applies or induces the current through the first solenoid). The applied or induced current may be small enough so that the magnetic field so generated is not strong enough to move the magnet away from the first position. Similarly, in the latter case, the default value is that the current through the first solenoid is strong enough to keep the magnet in the first position by magnetic attraction. The applied electrical signal may directly apply or induce a current in the first solenoid, which will cause the drop in the current in the first solenoid to be large enough to be measured, but with a small enough amplitude so that the first solenoid still provides a strong enough magnetic field to keep the magnet in the first position. Of course, in this latter case, an additional signal on top of the normal signal may also be used.

[0032] The detector can be part of a safety actuator board (e.g., an electronic board configured to control a first solenoid to move a magnet from a first position to a second position). This allows the detector to be conveniently included as part of an existing component of an elevator system. Alternatively, the detector can be separate from the safety actuator board.

[0033] It will be appreciated that all preferred and optional features that have been discussed above in relation to either the first aspect of the disclosure or one of the second aspects of the disclosure may also be applicable to the other aspects and are therefore also corresponding preferred and optional features of the other aspects. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Certain preferred examples of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0035] Figure 1 The safety actuator is schematically shown with its magnet in a first "reset" position adjacent to a first solenoid;

[0036] Figure 2 The safety actuator is schematically shown with its magnet in a second "triggered" position away from the first solenoid;

[0037] Figure 3 is a perspective view showing a first solenoid and a second solenoid according to an example of the present disclosure connected to a safety actuator plate;

[0038] Figure 4 showing two graphs respectively representing an example of an electrical signal applied to a second solenoid and a corresponding voltage detected in a first solenoid according to an example of the present disclosure; and

[0039] Figure 5 is a flow chart representing a method according to aspects of the present disclosure. DETAILED DESCRIPTION

[0040] Figure 1 An electronic safety actuator 1 for an elevator car is shown. The safety actuator 1 has a first solenoid 2 which is wound around a first core 7 (e.g. a steel core) to form an electromagnet to which a magnet 3 (e.g. a permanent magnet) is selectively attached. The magnet 3 is contained by a second core 9 or block (e.g. a second steel core). In this figure, the magnet 3 is in a first position adjacent to the first solenoid 2, i.e. the air gap 5a between the first core 7 and the second core 9 is small or non-existent.

[0041] In this example, the magnet 3 is magnetically attached to the first core 7 by virtue of its own magnetic field. During normal use, the first solenoid 2 is not supplied with any current. Alternatively, the first solenoid 2 may be supplied with power during normal use, and when the power supply to the first solenoid 2 is removed, the safety actuation is enabled, as described above. Figure 1 In the configuration of , the magnet 3 is kept at a distance from and not in contact with the guide rail 4. A mechanical rod (not shown) attached to the magnet 3 is connected to an elevator safety brake (not shown) and, when driven parallel to the guide rail 4, causes the safety brake (e.g., via a wedge or roller brake mechanism) to engage with the guide rail 4 in order to stop the elevator car. In some examples, the magnet 3 may be the actual safety brake.

[0042] Figure 1 The electronic safety actuator 1 also includes a second solenoid 6 and a detector 8, which generates a magnetic circuit 10a, as described below.

[0043] Figure 2 Shown with Figure 1 , but with the magnet 3 in a second position away from the first solenoid 2, so that the first core 7 and the second core 9 are separated by a relatively large air gap 5b. In this position, the magnet 3 is magnetically attached to the guide rail 4. In this position, the friction between the guide rail 4 and the magnet 3 causes a rod (not shown) to be driven parallel to the guide rail 4 in order to engage the safety brake and stop the elevator car. Figure 2 The electronic safety actuator 1 also includes a second solenoid 6 and a detector 8, which generates a magnetic circuit 10b, as described below.

[0044] The magnet 3 is driven by the current applied to the first solenoid 2. Figure 1 The first position (also called the "reset" position) is moved to Figure 2The guide rail 4 is a guide rail 4 which ...

[0045] In use, an elevator car will typically have two safety brakes and two electric actuators, each of which is Figure 1 and Figure 2 In other examples, there may be only one safety brake, or more than two safety brakes (and a corresponding number of electronic actuators). A control unit (not shown) is capable of actuating both safety brakes. When an event requiring the safety brake to be engaged (e.g., an overspeed event or an over-acceleration event) occurs, the control unit operates ( Figure 3 ) a switch of the safety actuation plate 38, which releases the first solenoid 2 or triggers the magnet 3 to Figure 2 The safety brake is placed in a track-engaging ("triggering") position, thereby lifting a lever (not shown) connected to a wedge or roller of a corresponding safety brake.

[0046] The electronic safety actuator 1 according to the present disclosure further comprises a second solenoid 6 (also referred to as a control coil or a monitoring coil), such as Figure 1 , Figure 2 and Figure 3 In the example of the attached drawings, the second solenoid 6 has a small number of turns, such as a single turn or a few turns. The first solenoid 2 and the second solenoid 6 are connected in a Figure 3 As shown in Figure 3 As can be seen in FIG, the second solenoid 6 has only a few turns, far fewer than the first solenoid 2, and is arranged coaxially with the first solenoid 2 and wound around the same bobbin (and around the same first core 7).

[0047] like Figure 3 As seen in FIG. 1 , the first solenoid 2 has a first end 30 and a second end 32, which form a connector (through which current can be driven) for each end of the first solenoid 2. The second solenoid 6 also has a first end 34 and a second end 36, which form a connector (through which current can be driven) for each end of the second solenoid 6. Each of the ends is individually connected to a safety actuator board (SAB) 38.

[0048] According to the present disclosure, there is also provided Figure 1 , Figure 2 and Figure 3 Detector 8 as seen in FIG. Figure 4 ) is introduced by the detector 8 into the first solenoid 2 or the second solenoid 6 (through their respective connectors 30, 32 or 34, 36). This creates a magnetic circuit 10a, 10b in the electronic safety actuator 1 (as shown in FIG. Figure 1 and Figure 2 ), which in turn induces a current in the other of the two coils 2, 6, which current can then be detected, for example, as a current or a voltage.

[0049] The magnetic circuit 10a, 10b is a closed loop path containing magnetic flux. The flux is generated by the first solenoid 2 or the second solenoid 6 (whichever the electrical signal is applied to). The flux is confined to the path by the cores 7 and 9 and the magnet 3.

[0050] exist Figure 1 In the case of , there is a minimum air gap 5a between the cores 7, 9, so that the closed loop path of the magnetic flux 10a effectively contains no air gap. As a result, the magnetic circuit 10a has a low magnetic resistance, and the induced current approximates the behavior of a transformer in which the ratio of the voltages in the two coils is proportional to the number of coils in each solenoid, as represented by the following relationship.

[0051]

[0052] When magnet 3 is Figure 1 This known relationship can be used to determine a reference value, for example for theoretically predicting the expected value of the voltage induced in the first solenoid 2 or the second solenoid 6 (based on the electrical signal applied to the other solenoid) when the first position shown in . Alternatively or additionally, test measurements can be performed to determine the reference value. The reference value can also be obtained from the applied signal directly or via an amplifier or a voltage divider or a current divider (in order to appropriately scale it for comparison).

[0053] Detector 8 detects an induced electrical signal on one of the solenoids 2, 6 (based on the electrical signal applied to the other solenoid 2, 6). This detected induced signal can then be compared with a reference value to determine the state or condition of a portion of the elevator safety actuator, as described below.

[0054] exist Figure 2 In the embodiment, the magnet 3 is in the second position (i.e., the triggered position). In this position, there is a large air gap 5b between the cores 7, 9. As a result, the closed loop path of the magnetic flux includes the air gap 5b. This significantly increases the magnetic resistance of the magnetic circuit 10b and correspondingly reduces the electrical signal induced in the other solenoid by the electrical signal applied to one solenoid 2, 6. In this case, the detected induced signal can also be compared with a reference value. The significant reduction in the signal compared to the reference value (or expected value) can be used to determine whether the magnet 3 is in the second position (i.e., the triggered position). Figure 2In the second (trigger) position of the magnet, as further described below. Similarly, with the magnet in an intermediate position, a relatively large air gap (smaller than the air gap present when the magnet 3 is in the second position) will be included in the closed loop of the magnetic circuit. This will cause the relationship of the induced electrical signal in one of the regulating coils to change, resulting in a change in the detected induced signal (compared to the value when the magnet was in the first position). In some examples, the reference value may be obtained with the magnet in a range of intermediate positions (and optionally also in the first position and / or the second position).

[0055] Figure 4 An example electrical signal 40 applied by the detector 8 to the second solenoid 6 is shown in the upper figure. Because the ratio of the number of turns in the first solenoid 2 to the number of turns in the second solenoid 6 is high, the signal (e.g., voltage) induced in the first solenoid 2 as a result of the electrical signal applied to the second solenoid 6 will be high, as represented in the lower figure (which shows the induced electrical signal 42). This allows a small voltage to be applied to the second solenoid 6 while still inducing a voltage in the first solenoid 2 that is large enough (to be reliably measured) and has a high sensitivity. For example, if the first solenoid 2 has 800 turns, and the second solenoid 6 (monitoring coil) has 10 turns, then the turns ratio is 80:1, and a voltage of 10mV applied to the second solenoid 6 will induce a voltage of approximately 0.8V in the first solenoid 2.

[0056] The relationship is reversed for current, i.e. a small current applied to the first solenoid 2 induces a larger current in the second solenoid 6, so that in the example where the electrical signal to be measured is current and it is measured in the second solenoid 6, only a small current needs to be applied to the first solenoid 2. This improves the life of the first solenoid 2 and the second solenoid 6 because they are subject to lower voltages and currents.

[0057] It will be appreciated that in other examples it is also feasible to use a large voltage applied to the first solenoid 2 to produce a small voltage to be detected in the second solenoid 6, or to apply a large current to the second solenoid 6 in order to produce a small current to be detected in the first solenoid 2. While these arrangements are less desirable from a sensitivity perspective, there may be other operational reasons for using such arrangements.

[0058] The relationships presented above allow the expected value of the induced electrical signal (current or voltage) to be calculated, e.g. for Figure 1 The position of the magnet 3 is shown in FIG.

[0059] The induced electrical signal may be different from the expected value. For example, as described above, when the magnet 3 is Figure 2When the magnet 3 is in the second (trigger) position, the closed loop 10b of the magnetic flux includes the air gap 5b. This makes the induced electrical signal much lower than the expected reference value based on the above ideal ratio relationship. Figure 2 , the value of the induced electrical signal (e.g., current or voltage) may be, for example, 80% or more lower than the expected value when the induced value is in the second position as shown in . In the event that the induced value is very much lower than the expected or predicted value, this allows a determination that the magnet 3 is definitely in the second position. Such a large loss of signal cannot reasonably be attributed to wear in the first solenoid 2 (which would normally be expected to result in a loss of only a few percentage points of signal), and therefore, such a determination can be made separately from wear monitoring using the same detector.

[0060] Similarly, in the case where the magnet 3 is in the intermediate position, the closed loop will still include an air gap (although smaller than the air gap 5b). The amount by which the induced electrical signal is below the expected reference value will depend on the size of the air gap (i.e., on the distance of the magnet 3 from the first solenoid 2), so that the induced electrical signal can be used to determine whether the magnet is in the intermediate position. The dependence can be a simple linear dependence or can be more complex. It can be determined by measuring a series of test values ​​at different intermediate positions.

[0061] As noted, the induced electrical signal may also be lower than the expected induced electrical signal as a result of wear that occurs in the first solenoid 2. For example, if the first solenoid 2 is heated above a certain temperature, the coating on the conductor that forms the coil (e.g., a resin coating on a copper wire) will begin to soften or melt. This may cause contact between adjacent coils of the first solenoid 2, thereby effectively reducing the number of turns in the solenoid 2. This will cause the induced electrical signal to be lower than expected based on the ratio relationship, but not as low as in the case where the magnet 3 is in the second position. For example, the induced electrical signal may be within 40%, 20%, or even 10% of the expected value. In many cases, the loss of only a small number of turns will result in a deviation of less than 5% from the expected signal.

[0062] Therefore, a comparison of the induced electrical signal detected by the detector 8 with a predicted or expected value can be used to determine the position of the magnet 3 and also to detect wear in the first solenoid 2 .

[0063] As noted above, in alternative arrangements, depending on the turns ratio and the choice of first solenoid / second solenoid as the detector and voltage / current as the measured characteristic, the signal may be greater than the expected or predicted value, rather than less than it.

[0064] Therefore, there is also disclosed a method for detecting the condition or state of a first solenoid 2 or magnet 3 of an electronic safety actuator 1 for an elevator safety brake, such as Figure 5 as shown in the flow chart.

[0065] In a first step 50, the detector 8 is used to apply the electrical signal 40 to the first solenoid 2 or the second solenoid 6. Next, in step 52, the detector 8 detects the electrical signal 42 induced in the other of the first solenoid 2 and the second solenoid 6 as a result of the electrical signal applied in step 50. Then, in step 54, the detected electrical signal is compared with a reference value.

[0066] The reference value may be calculated or predicted using the known relationship described above, or may be determined or measured in testing if the position of the magnet 3 is known, for example by measuring the induced voltage in a test run immediately after installation.

[0067] In case the value of the induced electrical signal is close to or even equal to the reference value, it is determined in step 56 that the magnet 3 is in the first position, such as Figure 1 . This may be the case, for example, when the detected electrical signal is within 20% of the reference value (or more generally within a given range of the reference value). In this case, in step 58, a wear value may then be calculated, for example, by subtracting the detected induced signal from the reference value. The wear value may be indicative of the severity of the wear within the first solenoid 2.

[0068] Alternatively, in step 60, it may be determined that the induced electrical signal is away from the reference value, for example, when the detected electrical system is 50% or 80% or more below the reference value. In this case, such a large difference is definitely an air gap (e.g. Figure 2 ), and thus a determination will be made that the magnet 3 is in an intermediate position or in the second position, ie the magnet 3 is not in the first position.

[0069] Then, at step 62, the comparison between the induced electrical signal and the reference value can be used to determine a specific position of the permanent magnet 3, such as the magnet 3 in the second position, or in an intermediate position between the first position and the second position. If it is determined that the magnet 3 is in an intermediate position, then step 62 may also include determining the approximate distance of the magnet 3 from the first position, i.e., at which specific intermediate position the magnet 3 is. This can be done, for example, by comparing the detected electrical signal with measured values ​​or predicted values ​​for a series of intermediate positions, and determining that the magnet 3 is at the intermediate position that gives the value closest to the detected electrical signal.

Claims

1. An electronic safety actuator (1) for an elevator safety brake, comprising: A first solenoid (2); a magnet (3) movable by the first solenoid (2) between a first position adjacent to the first solenoid (2) and a second position away from the first solenoid (2); A second solenoid (6); as well as A detector (8) arranged to apply an electrical signal to one of the first solenoid (2) and the second solenoid (6), detect an electrical signal induced in the other of the first solenoid (2) and the second solenoid (6) as a result of the applied electrical signal, and determine a condition or state of the first solenoid (2) or the magnet (3) based on the detected electrical signal.

2. The electronic safety actuator (1) according to claim 1, wherein: The detector (8) is further arranged to determine the condition or state of the first solenoid (2) or the magnet (3) by comparing the detected electrical signal with at least one reference value.

3. The electronic safety actuator (1) according to claim 1, wherein: The induced electrical signal is insufficient to move the magnet between the first position and the second position.

4. The electronic safety actuator (1) according to any one of claims 1 to 3, wherein: The detector is arranged to detect a voltage across the first solenoid or across the second solenoid.

5. The electronic safety actuator (1) according to claim 4, wherein: The detector is arranged to apply the electrical signal to the second solenoid (6) and to measure the voltage induced in the first solenoid (2).

6. The electronic safety actuator (1) according to any one of claims 1 to 3, wherein: The number of turns of the second solenoid (6) is less than half the number of turns of the first solenoid (2).

7. The electronic safety actuator (1) according to any one of claims 1 to 3, wherein: The number of turns of the second solenoid (6) is less than 20 turns.

8. The electronic safety actuator (1) according to any one of claims 1 to 3, wherein: The detector is arranged to detect current in the first solenoid or the second solenoid.

9. The electronic safety actuator (1) according to claim 8, wherein: The detector (8) is arranged to apply the electrical signal to the first solenoid (2) and to measure the current induced in the second solenoid (6).

10. The electronic safety actuator (1) according to any one of claims 1 to 3, wherein: The first solenoid (2) and the second solenoid (6) are coaxial.

11. A method of detecting a condition or state of a first solenoid (2) or a magnet (3) of an electronic safety actuator (1) for an elevator safety brake, the magnet (3) being movable by the first solenoid (2) between a first position adjacent to the first solenoid (2) and a second position remote from the first solenoid (2), the method comprising: applying an electrical signal to the first solenoid (2) or the second solenoid (6); detecting an electrical signal induced in the other of the first solenoid (2) and the second solenoid (6) as a result of the applied electrical signal; as well as The condition or state is determined based on the detected electrical signal.

12. The method as claimed in claim 11, comprising determining the position of the magnet (3).

13. The method of claim 11, comprising detecting whether the magnet is in an intermediate position between the first position and the second position.

14. The method of any one of claims 11 to 13, comprising determining that the magnet (3) is in the first position when the detected electrical signal differs from a first reference value; wherein the first reference value is at least 80% of the electrical signal expected based on an undamaged coil.

15. The method of any one of claims 11 to 13, wherein determining the condition or state based on the detected electrical signal comprises detecting wear in the first solenoid (2).

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