Patent Description:
In order to ensure the safety of an elevator, standards stipulate that a brake device of an elevator system needs to be equipped with a brake switch to detect a position state of a movable plate of the brake device. When the position of the movable plate moves from a braking position to a non-braking position or vice versa, the movable plate will press or release the brake switch, thereby feedbacking whether the movable plate is in the braking position through the switching of the brake switch. Since the brake switch is installed on a stationary plate, the position thereof may change after being repeatedly contacted by the movable plate. When the position thereof changes to a certain extent, the state of the movable plate cannot be accurately detected. At this point, the elevator system cannot operate normally due to safety considerations when the position state of the movable plate cannot be known.

Of all the emergency repair reports of the brake device, a very large proportion is related to the position of the brake switch. Maintaining the brake switch in the proper position is very important for the normal operation of the elevator system.

<CIT> discloses a brake device of an elevator hoist comprising a brake coil part and an armature part and is configured to suck the armature part by an electromagnetic force generated in the brake coil part during an operation of a hoist, operate the armature part to a brake surface side of a rotor interlocking with rotation of the hoist when the hoist is braked, and perform operation confirmation of the armature part by a brake operation confirmation switch. This document discloses a device for an elevator brake device according to the preamble of claims <NUM> and <NUM>.

<CIT> discloses brake diagnostic device comprising an encoder detecting the rotation of a motor to move a cage up and down and a motor speed detection device. A brake control device releases the motor by increasing a brake current to a brake device which stops the rotation of the motor when closed. If the motor starts rotating, the brake control device decreases the brake current until the rotation of the motor stops. A measurement section measures a time period from the point when the brake current starts flowing until the motor starts to rotate, and another time period from when the brake current starts decreasing until the motor actually stops.

An object of the present disclosure is to solve or at least alleviate the problems existing in the prior art.

According to an aspect of the invention, there is provided a self-checking device for an elevator brake device as claimed in claim <NUM>.

Optionally, in an embodiment of the self-checking device, the processor is configured to determine that the brake switch is in the proper position when (t<NUM>-t<NUM>) is in a range of a<NUM>(t<NUM>-t<NUM>) to a<NUM>(t<NUM>-t<NUM>), and that the brake switch is in an improper position when (t<NUM>-t<NUM>) is outside the range of a<NUM>(t<NUM>-t<NUM>) to a<NUM>(t<NUM>-t<NUM>), and wherein a<NUM> is selected from <NUM>-<NUM> and a<NUM> is selected from <NUM>-<NUM>.

Optionally, in an embodiment of the self-checking device, the controller is configured to increase or decrease the voltage at a first rate in a first section before the fluctuation position, to increase or decrease the voltage at a second rate in a second section including the fluctuation position, and to increase or decrease the voltage at a third rate in a third section after the fluctuation position, wherein the second rate is lower than the first rate and the third rate.

Optionally, in an embodiment of the self-checking device, the controller is configured to apply the voltage gradually increasing from <NUM>% to <NUM>% or gradually decreasing from <NUM>% to <NUM>% in a way of pulse width modulated duty cycle.

Optionally, in an embodiment of the self-checking device, the controller is configured to repeat the self-checking at a specific time interval.

Optionally, in an embodiment of the self-checking device, the processor is configured to send a notification when the brake switch is not properly installed.

According to a further aspect of the invention, there is provided an elevator system as claimed in claim <NUM>.

According to a yet further aspect of the invention, there is provided a self -checking method for an elevator brake device as claimed in claim <NUM>.

Optionally, the self-checking method further includes: determining that the brake switch is in the proper position when (t<NUM>-t<NUM>) is in a range of a<NUM>(t<NUM>-t<NUM>) to a<NUM>(t<NUM>-t<NUM>), and that the brake switch is in an improper position when (t<NUM>-t<NUM>) is outside the range of a<NUM>(t<NUM>-t<NUM>) to a<NUM>(t<NUM>-t<NUM>), wherein a<NUM> is selected from <NUM>-<NUM> and a<NUM> is selected from <NUM>-<NUM>.

Optionally, the self-checking method further includes: increasing or decreasing the voltage at a first rate in a first section before the fluctuation position, increasing or decreasing at a second rate in a second section including the fluctuation position, and increasing or decreasing at a third rate in a third section after the fluctuation position, wherein the second rate is lower than the first rate and the third rate.

Optionally, the self-checking method further includes: applying the voltage gradually increasing from <NUM>% to <NUM>% or gradually decreasing from <NUM>% to <NUM>% in a way of pulse width modulated duty cycle.

Optionally, the self-checking method further includes: repeating the method at a specific time interval.

Optionally, the self-checking method further includes: sending a notification when the brake switch is not properly installed.

According to a yet further aspect of the invention, there is provided a computer-readable medium, in which a computer program is stored as claimed in claim <NUM>.

The self-checking and method according to the embodiments of the present disclosure can monitor the position of the brake switch.

With reference to the accompanying drawings, the content of the present disclosure will become easier to understand. It can be easily understood by those skilled in the art that these drawings are only for illustrative purpose, and are not intended to limit the scope of protection of the appended claims. In addition, similar numbers in the drawings are used to denote similar components, in which:.

With reference to <FIG>, a perspective view of an exemplary brake system for an elevator system and cross-sectional views thereof in a braking state and a non-braking state are shown respectively. The brake device includes a bracket <NUM>, a frame <NUM> fixed to the bracket <NUM>, a brake disc <NUM> coupled to a drive shaft of the elevator system, a movable plate <NUM> and a stationary plate <NUM>. The movable plate <NUM> and the frame <NUM> are located on both sides of the brake disc <NUM>, and friction plates are provided on the side thereof that faces the brake disc <NUM>. As shown in <FIG>, a spring <NUM> is located between the movable plate <NUM> and the stationary plate <NUM>, and the spring <NUM> is compressed to tend to push the brake pads on the movable plate <NUM> and the frame <NUM> to contact the brake disc <NUM> on the drive shaft and cause friction with the brake disc <NUM> so as to restrain the rotation of the drive shaft. The stationary plate <NUM> is also provided with an electromagnetic coil <NUM>, which can generate a magnetic field when energized, thereby attracting the movable plate <NUM> to move closer to the stationary plate <NUM> and away from the brake disc <NUM>. Consequently, the brake disc <NUM> is released, so that the drive shaft connected to the brake disc <NUM> can rotate freely and drive an elevator car to ascend or descend. A brake switch <NUM> may be located between the stationary plate <NUM> and the movable plate <NUM>. When the movable plate <NUM> is attracted to approach the stationary plate <NUM> or driven by the spring <NUM> to move away from the stationary plate <NUM>, it will contact the brake switch <NUM> and switch the state of the brake switch <NUM>. Therefore, the position of the movable plate <NUM>, that is, the state of the brake device, can be determined through the signal of the brake switch <NUM>. The brake switch <NUM> is generally fixed to the stationary plate <NUM> through a bracket. During the initial installation, the work staff will set the position of the brake switch <NUM> so that it can accurately detect whether the movable plate is in the braking position shown in <FIG> or the non-braking position shown in <FIG>. However, the position of the brake switch <NUM> will deviate during use, and when the deviation reaches a certain extent, it is possible that the position state of the movable plate <NUM> cannot be recognized or may be incorrectly recognized, thereby the safety system of the elevator system fails to know the state of the movable plate and stops the operation of the elevator system for safety consideration. At this point, the user will report the failure, and the technicians need to rush to the site for repairing for example adjusting the position of the brake switch <NUM>. The emergency repairs caused by the position of the brake switch <NUM> may account for a large proportion of the total repairs. Therefore, it is desirable to provide a device and a method that can detect the deviation of the brake switch <NUM> and notify maintenance personnel when the brake switch <NUM> deviates so as to adjust it to a proper position during routine maintenance.

According to an aspect, a self-checking device and a self-checking method for an elevator brake device are provided. The method includes: enabling an elevator to enter a test mode; gradually increasing a voltage applied to the electromagnetic coil <NUM> of the brake device in a predetermined pattern when the brake device is in the braking state shown in <FIG>, or gradually decreasing the voltage applied to the electromagnetic coil <NUM> of the brake device in a predetermined pattern when the brake device is in the non-braking state shown in <FIG>; recording a first time t<NUM> when the brake switch <NUM> of the brake device is triggered; and determining whether the brake switch <NUM> is in a proper position based on the first time t<NUM>. The so-called "proper position" may refer to a position range in which the brake switch <NUM> can operate normally within an allowable deviation amount near a pre-installation position. The self-checking method can be executed based on time, for example, at a regular time interval, such as once every other week, every other ten days or every other month, or before routine maintenance, etc. The self-checking method can be executed when the elevator system is not braked, for example, at night. Generally speaking, the self-checking method starts to be executed when the brake device is in a braking state and the elevator is stopped. First, the elevator enters the test mode, for example, under the control of a controller. The controller can determine whether it is suitable for the elevator to enter the test mode based on factors such as time, current load of elevators, current number of elevators, etc. After entering the test mode, the controller will no longer accept other instructions such as elevator-calling instructions before the elevator completes the self-checking. Subsequently, the controller can control a voltage applying device such as that of the brake device to gradually increase the voltage applied to the electromagnetic coil <NUM> of the brake device in a predetermined pattern. At the same time, the control system of the elevator will provide torque to keep the car position unchanged. The "predetermined pattern" means that the voltage is applied to the electromagnetic coil <NUM> in a gradually increasing predetermined voltage waveform or voltage curve. For example, as shown in <FIG>, the voltage increases linearly in three sections with different slopes, including a first section <NUM> to a, a second section a to b, and a third section b to c. The voltage increasing rates of various sections (that is, the slopes of the curves of various sections) are different. In an alternative embodiment, the voltage increasing mode or pattern may be different from the illustrated embodiment; for example, there are only two linear sections or only one linear section. Subsequently, for example, a processor may record the first time t<NUM> when the brake switch <NUM> of the brake device is triggered, and determine whether the brake switch <NUM> is in the proper position based on the first time t<NUM>.

The first time t<NUM> when the brake switch <NUM> is triggered is associated with the position where the brake switch <NUM> is located. When the position of the brake switch <NUM> starts to deviate, the first time t<NUM> will also change. Therefore, it can be determined whether the brake switch <NUM> is in the proper position based on the difference or deviation of the first time t<NUM>. For example, in some embodiments, the method may include: determining a reference trigger time t<NUM> of the brake switch based on a correct installation position of the brake switch <NUM> during commissioning; and determining whether the brake switch <NUM> is in the proper position based on the difference between the first time t<NUM> and the reference trigger time t<NUM>. For example, the reference trigger time t<NUM> can be measured during the installation and commissioning of the elevator system, and the difference between the first time t<NUM> and the reference trigger time t<NUM> can be determined in the actual test. When the difference between the two reaches a certain degree, it is considered that the position of the brake switch <NUM> needs to be adjusted; otherwise, the normal operation of the elevator may be affected.

In some embodiments, the method further includes: monitoring the current of the electromagnetic coil. As shown in <FIG>, there is a correspondence between the current curve and the voltage curve. Further, the fluctuation of the current of the electromagnetic coil is recorded, and a second time t<NUM> at the beginning of the fluctuation of the current and a third time t<NUM> at the trough of the fluctuation of the current are recorded; and it is determined whether the brake switch <NUM> is in the proper position based on a relative relationship among the first time t<NUM>, the second time t<NUM> and the third time t<NUM>. It should be understood that the fluctuation w in the current curve can be explained by the Lenz's law, and the second time t<NUM> at the beginning of the fluctuation for example corresponds to the time when an electromagnetic force generated by the electromagnetic coil <NUM> just exceeds the spring force exerted by the spring <NUM> and the movable plate <NUM> just begins to separate from the brake disc <NUM>; and the third time t<NUM> at the trough of the fluctuation of the current corresponds to the time when the movable plate <NUM> just begins to engage with the stationary plate <NUM>. It should be understood that the first time t<NUM> when the brake switch <NUM> is triggered should be between the second time t<NUM> and the third time t<NUM>, since the movable plate <NUM> first triggers the brake switch <NUM> after separating from the brake disc <NUM> and then contacts the stationary plate <NUM>. Therefore, it can be determined whether the brake switch <NUM> is in the proper position based on a relative relationship among the first time t<NUM>, the second time t<NUM> and the third time t<NUM>. For example, in some embodiments, a function related to the first time t<NUM>, the second time t<NUM> and the third time t<NUM> can be set, and when the first time t<NUM>, the second time t<NUM> and the third time t<NUM> actually detected satisfy the function, it is considered that the brake switch <NUM> is properly positioned; otherwise, it is considered that the position of the brake switch <NUM> has deviated and needs to be adjusted. The specific function can be set in consideration of factors such as the actual installation condition and the tolerance to the switch position deviation. For example, in a non-limiting example, it may be determined that the brake switch <NUM> is in the proper position when (t<NUM>-t<NUM>) is in a range of a<NUM>(t<NUM>-t<NUM>) to a<NUM>(t<NUM>-t<NUM>), and when (t<NUM>-t<NUM>) is outside the range of a<NUM>(t<NUM>-t<NUM>) to a<NUM>(t<NUM>-t<NUM>), it is determined that the brake switch is in an improper position, wherein a<NUM> is for example selected from <NUM>-<NUM> and a<NUM> is selected from <NUM>-<NUM>. That is, when t<NUM> is in the middle area between t<NUM> and t<NUM> or in an area closer to t<NUM>, it is considered that the brake switch <NUM> is properly positioned; otherwise, it is considered that the position of the brake switch <NUM> has deviated and needs to be adjusted. In other embodiments, a relationship among the magnitudes of the currents on the current curve at the first time t<NUM>, the second time t<NUM> and the third time t<NUM> can also be used as the basis for the judgment. More specifically, it can be determined whether the brake switch is in the proper position based on a relative relationship among a current I<NUM> at the first time t<NUM>, a current I<NUM> at the second time t<NUM> and a current I<NUM> at the third time t<NUM>. For example, in some embodiments, a function related to the current I<NUM> at the first time t<NUM>, the current I<NUM> at the second time t<NUM> and the current I<NUM> at the third time t<NUM> can be set, and when the current I<NUM> at the first time t<NUM>, the current I<NUM> at the second time t<NUM> and the current I<NUM> at the third time t<NUM> that are actually detected satisfy the function, it is considered that the brake switch <NUM> is properly positioned; otherwise, it is considered that the position of the brake switch <NUM> has deviated and needs to be adjusted. In some embodiments, a judgment reference function can be determined based on a relationship among a reference trigger time t<NUM>, a reference second time t<NUM>' and a reference third time t<NUM>' in a reference test, and it is determined whether the first time t<NUM>, the second time t<NUM> and the third time t<NUM> in the actual test satisfy the judgment reference function, thereby determining whether the position of the brake switch <NUM> needs to be adjusted; similarly, the reference function can also be set according to reference currents I<NUM>, I<NUM> and I<NUM> during the test.

In some embodiments, the applied voltage increases at a first rate in the first section <NUM>-a before the fluctuation position, increases at a second rate in the second section a-b including the fluctuation position, and increases at a third rate in the third section after the fluctuation position, wherein the second rate is lower than the first rate and the third rate. It should be understood that increasing the voltage at a reduced rate in the second section where the fluctuation will occur can amplify the fluctuation, thus making it easier and more accurate to detect the relationship among the first time t<NUM>, the second time t<NUM> and the third time t<NUM>. In addition, in the first section and the third section, the voltage should be increased at a rate as large as possible, thereby shortening the entire test cycle, and avoiding long-term testing that affects the normal operation of the elevator. It should be understood that during the entire test, in addition to the fluctuation caused by the movement of the movable plate, the current may be disturbed by other factors. At this point, since the signal indicating that the brake switch <NUM> is triggered is not received in the fluctuation time interval, the processor will ignore this current fluctuation. It should be understood that there are two fluctuations D and E in the ascending section of the curve shown in <FIG>, which respectively correspond to the movements of the movable plates driven by the two coils, whereas the two trough parts can be used as independent curves for determining the position of the brake switch of each movable plate. If the mode in which only one brake is released in each test is used, that is, the other brake is always in the braking state during the test, only one trough corresponding to the switch signal will be seen. In addition, although not seen in the curve shown, there may also be disturbing troughs in the curve, which are generated by other factors such as the inclination of the movable plate of the brake or uneven air gap. These disturbing troughs can be excluded by determining whether there are corresponding switch signals. In addition, the curve of <FIG> also shows fluctuations F and G in the descending section, which can be used in a similar manner to determine the installation position of the brake switch.

In some embodiments, the voltage may be applied gradually increasing from <NUM>% to <NUM>% or gradually decreasing from <NUM>% to <NUM>% in a way of pulse width modulated duty cycle. In some embodiments, a notification can be sent to maintenance personnel when the brake switch is not properly installed. For example, the maintenance personnel can adjust the brake switch to the proper position in the next daily maintenance, thereby preventing the elevator system from stopping operating due to the deviation of the position of the brake switch.

The self-checking device and method according to the present disclosure can provide an early warning for the position deviation of the brake switch to remind the work staff to adjust the brake switch to the proper position during routine maintenance, thereby avoiding malfunctions caused by the deviation of the position of the brake switch.

Claim 1:
A self-checking device for an elevator brake device, comprising:
a controller, which controls a voltage applied to an electromagnetic coil (<NUM>) of the elevator brake device, and which is configured to: enable an elevator to enter a test mode; gradually increase the voltage applied to the electromagnetic coil of the brake device in a predetermined pattern when the brake device is in a braking state, or gradually decrease the voltage applied to the electromagnetic coil of the brake device in a predetermined pattern when the brake device is in a non-braking state; and
a processor, which is configured to receive and record a first time t<NUM> when a brake switch (<NUM>) of the brake device is triggered, characterised in that the processor is further configured to determine whether the brake switch is in a proper position based on the first time t<NUM>,
wherein the processor is further configured to: monitor a current of the electromagnetic coil (<NUM>); record the fluctuation of the current of the electromagnetic coil, and record a second time t<NUM> at the beginning of the fluctuation of the current and a third time t<NUM> at the trough of the fluctuation of the current; and determine whether the brake switch (<NUM>) is in the proper position based on a relative relationship among the first time t<NUM>, the second time t<NUM> and the third time t<NUM>, or determine whether the brake switch is in the proper position based on a relative relationship among a current I<NUM> at the first time t<NUM>, a current I<NUM> at the second time t<NUM> and a current I<NUM> at the third time t<NUM>, and/or,
wherein the processor is further configured to: determine a reference trigger time t<NUM> of the brake switch (<NUM>) based on a correct installation position of the brake switch during commissioning; and determine whether the brake switch is in the proper position based on the difference between the first time t<NUM> and the reference trigger time t<NUM>.