Patent Description:
Although safeties are key components of an elevator system, unwanted actuation causes an operational nuisance due to a shutdown period that may ensue. False engagement of safeties and/or false actuation of the car overspeed governor overspeed (OS) switch can arise from e-stops, or unintended motion in the elevator car due to inertial impulses. This may occur due to people jumping in the elevator car or a counterweight jump, for example. Either type of jump could be just high enough to cause a momentary increase in elevator car velocity, causing operation system switch actuation and is accompanied by or is followed by actual safety engagement. Operation system switch actuation refers to an overspeed governor overspeed switch in some situations. Resolution of the issue may require a mechanic to visit the site for resetting and rescue of passengers.

<CIT> describes an electromagnetic safety trigger including a link kinematically connected to a safety of an elevator system mass, such as an elevator car or counterweight. An electromagnet mounted on a linear actuator is magnetically coupled to the link, and a spring is connected between the link and the elevator mass. The electromagnet can be triggered to release the link, which allows the spring to move the link to engage the safety.

<CIT> describes an elevator apparatus where running of a car is braked by a first brake device and a second brake device. Operations of the first brake device and the second brake device are controlled by a brake control portion. When a sudden stop command to make a sudden stop of the car is issued, the brake control portion first causes the first brake device to perform braking operation. When the deceleration of the car is equal to or smaller than a predetermined value after a lapse of a predetermined time, the brake control portion causes the second brake device to perform braking operation.

According to a first aspect of the present invention, there is provided a method of avoiding inadvertent resetting of a safety brake of an elevator system in accordance with claim <NUM>. The method includes obtaining data with at least one sensor associated with an electronic safety actuator. The method also includes determining whether resetting of a safety brake is made based on an algorithm that compares the data obtained by the sensor(s) and a threshold condition, resetting of the safety brake occurring if the threshold condition is exceeded for equal to or greater than a predetermined amount of time.

Further embodiments may include that the data obtained by the at least one sensor is velocity data and the threshold condition is a threshold velocity.

Further embodiments may include that the data obtained by the at least one sensor is acceleration data and the threshold condition is a threshold acceleration.

Further embodiments may include analyzing the data obtained with the at least one sensor. Also included is modifying the algorithm based on actual use of the safety brake.

Further embodiments may include that analyzing the data obtained with the at least one sensor is conducted at a remote site, the at least one sensor in operative communication with a processing device at the remote site.

Further embodiments may include that analyzing the data obtained with the at least one sensor is conducted on site by an individual.

<FIG> and <FIG> illustrate a brake assembly <NUM> for an elevator system <NUM>, with <FIG> showing the broader elevator system <NUM> and <FIG> depicting an enlarged portion of <FIG>, specifically the brake assembly <NUM>. The elevator system includes an elevator car <NUM> that moves through an elevator car passage <NUM> (e.g., hoistway). The elevator car <NUM> is guided by one or more guide rails <NUM> connected to a sidewall of the elevator car passage <NUM>. The embodiments described herein relate to an overall braking system that is operable to assist in braking (e.g., slowing or stopping movement) of the elevator car <NUM>. In one embodiment, the braking is performed relative to the guide rail <NUM>. The brake assembly <NUM> can be used with various types of elevator systems.

The brake assembly <NUM> includes a safety brake <NUM> and an electronic safety actuator <NUM> that are each operatively coupled to the elevator car <NUM>. In some embodiments, the safety brake <NUM> and the electronic safety actuator <NUM> are mounted to a car frame <NUM> of the elevator car <NUM>. The safety brake <NUM> includes a brake member <NUM>, such as a brake pad or a similar structure suitable for repeatable braking engagement, with the guide rail <NUM>. The brake member <NUM> has a contact surface <NUM> that is operable to frictionally engage the guide rail <NUM>. In one embodiment, the safety brake <NUM> and an electronic safety actuator <NUM> may be combined into a single unit.

The safety brake <NUM> is operable between a non-braking position and a braking position. The non-braking position is a position that the safety brake <NUM> is disposed in during normal operation of the elevator car <NUM>. In particular, the contact surface <NUM> of the brake member <NUM> is not in contact with, or is in minimal contact with, the guide rail <NUM> while in the non-braking position, and thus does not frictionally engage the guide rail <NUM>. In the braking position, the frictional force between the contact surface <NUM> of the brake member <NUM> and the guide rail <NUM> is sufficient to stop movement of the elevator car <NUM> relative to the guide rail <NUM>. Various triggering mechanisms or components may be employed to actuate the safety brake <NUM> and thereby move the contact surface <NUM> of the brake member <NUM> into frictional engagement with the guide rail <NUM>. In the illustrated embodiment, a link member <NUM> is provided and couples the electronic safety actuator <NUM> and the safety brake <NUM>. Movement of the link member <NUM> triggers movement of the brake member <NUM> of the safety brake <NUM> from the non-braking position to the braking position.

In operation, an electronic sensing device and/or a controller <NUM> is configured to monitor various parameters and conditions of the elevator car <NUM> and to compare the monitored parameters and conditions to at least one predetermined condition. In one embodiment, the predetermined condition comprises speed and/or acceleration of the elevator car <NUM>. In the event that the monitored condition (e.g., speed, acceleration, etc.) meets or exceeds the predetermined condition, the electronic safety actuator <NUM> is actuated to facilitate engagement of the safety brake <NUM> and the guide rail <NUM>. In some embodiments, the electronic safety actuator <NUM> has a velocity sensor and an accelerometer. Data is analyzed by the controller and/or the electronic safety actuator <NUM> to determine if there is an overspeed or overacceleration condition. If such a condition is detected, the electronic safety actuator <NUM> activates, thereby pulling up on the link member <NUM> and driving the contact surface <NUM> of the brake member <NUM> into frictional engagement with the guide rail <NUM> - applying the brake(s). In some embodiments, the electronic safety actuator <NUM> sends this data to the elevator controller <NUM> and the controller sends it back to the electronic safety actuator <NUM> and tells it to activate.

In an embodiment, two electronic safety actuators <NUM> (one on each guide rail) are provided and connected to a controller on the elevator car <NUM> that gets data from the electronic safety actuators <NUM> and initiates activation of the electronic safety actuators <NUM> for synchronization purposes. In further embodiments, each electronic safety actuator <NUM> decides to activate on its own. Still further, one electronic safety actuator <NUM> may be "smart" and one is "dumb," where the smart electronic safety actuator gathers the speed/acceleration data and sends a command to the dumb one to activate along with the smart electronic safety actuator. The illustrated safety brake <NUM> and safety actuator <NUM> are merely examples of designs that may be employed in the embodiments described herein and it is to be understood that alternative designs may be utilized.

The examples described herein reduce the likelihood of a false trip of the safety brake <NUM> by utilizing the electronic safety actuator <NUM> which is electronically monitored and controlled. A false trip refers to actuation of the safety brake <NUM> by the electronic safety actuator <NUM> in response to a perceived overspeed or overacceleration condition that is not a true overspeed or overacceleration condition. For example, movement or jumping of passengers within the elevator car <NUM> may result in such a perceived, but not actual threat. Numerous other examples may result in false trip, including any impulsive movement of the elevator car <NUM>, the counterweight, or other elevator system equipment. The embodiments described herein provide a method of discerning between a false trip and a true overspeed or overacceleration condition by starting with basic theoretical algorithms (also referred to herein as "data model(s)") that filter out events known to cause false trips and may dynamically modify the algorithms during actual use over time by "learning" from events known to be a true overspeed or overacceleration condition or a false trip. These embodiments provide improvements over rigidly defined settings that strictly adhere to a rated condition, as will be appreciated from the description herein.

Monitoring and/or control of the electronic safety actuator <NUM> is facilitated with wired or wireless communication between the controller <NUM> and the electronic safety actuator <NUM>. In one embodiment, the electronic safety actuator may directly connect over a cellular, Bluetooth, or any other wireless connection to a processing device, such as the controller <NUM>, a mechanic's service tool (such as a mobile phone, tablet, laptop, or dedicated service tool), a remote computer, or a cloud server, for example, and monitoring and/or control may be handled by the connected device. The monitoring and/or control of the electronic safety actuator <NUM> may be carried out by manual command by an individual located in close or remote proximity to the brake assembly <NUM> and/or the controller <NUM>. In one embodiment, the monitoring and/or control may be carried out automatically by the controller <NUM>, a cloud server, or other remote computing device. An individual is considered in proximity to the brake assembly <NUM> when the individual is able to physically interact with the brake assembly <NUM> and/or the controller <NUM>. Interaction with the brake assembly <NUM> and/or the controller <NUM> may be carried out by manually contacting the structural components, such as with a tool, or may be done with a mobile device that is in wireless communication with the controller <NUM> directly or through a local network. This is considered on-site testing or maintenance. In other embodiments, a remote connection is established between the controller <NUM> and a remote device that is not located at the elevator system <NUM> location to perform the testing in what is referred to as remote testing. The remote device is connected to the controller <NUM> via a network <NUM> or some other remote wireless connection, such as cellular. Such a remote device may be operated by a remote operator in some embodiments, with the remote operator not required to be "on-site.

Referring now to <FIG>, velocity and/or acceleration profiles associated with actual use of the elevator system are illustrated. The data is obtained from electronic equipment that is part of, or associated with, the electronic safety actuator <NUM>. The equipment utilized may be one or more sensors, such as an accelerometer or a speed sensor, for example. The electronic safety actuator equipment monitors changes in velocity and/or acceleration as a function of time, as illustrated. As shown, brief periods of time where a predetermined maximum condition is exceeded may be present during normal use of the elevator system.

<FIG> is a plot of velocity (V) of the elevator car <NUM> as a function of time (T) and shows a velocity at which the elevator car is rated for use, Vrated. As shown proximate region <NUM>, exceeding of the rated velocity may occur for a number of reasons, including those discussed above, as well as a stopping process with an empty car in an upward direction or a full load in a downward direction is a scenario that may cause a false trip. Typically, exceeding a threshold velocity above the rated velocity would trigger the safety brakes, thereby resulting in a false trip. The current method utilizes an algorithm that takes into account the time in which the change in velocity occurs. In the illustrated embodiment, a threshold velocity is greater than the rated velocity. In some embodiments, the threshold velocity ranges from about <NUM>/s to about <NUM>/s and the rated velocity is about <NUM>/s. If the threshold velocity is exceeded for any time, the safety brake deployment may occur in some embodiments, regardless of the amount of time in which the threshold velocity was exceeded. However, if the velocity is between Vrated and the threshold velocity, and occurs for less than a predetermined time period, ΔT, a false trip is avoided. The predetermined time period, ΔT, is sufficient to filter out unwanted safety brake actuation, but sufficient to meet code requirements. The predetermined time period may vary depending upon the particular application, but an example time period is about <NUM> seconds.

<FIG> is a plot of acceleration (a) of the elevator car <NUM> as a function of time (T) and illustrates an acceleration profile with multiple brief periods at <NUM> and <NUM> of operation outside of the acceptable acceleration range, the range represented with numeral <NUM>. Such a situation may arise during bouncing of the elevator car <NUM>, such as when a passenger is jumping in the elevator car. The oscillation shown in the profile of <FIG> results in the brief periods represented with numerals <NUM>, <NUM>. To avoid false tripping, the method and system require that the velocity and/or acceleration exceed the threshold(s) for a period of time known to be greater than the brief periods associated with passenger jumping, for example. In some embodiments, the required period of time is about <NUM> seconds. For example, if the acceleration is between a rated acceleration of about <NUM>/s<NUM> when the car is travelling between floors and the threshold acceleration of about <NUM>/s<NUM> to about <NUM>/s<NUM> and occurs for less than a predetermined time period, ΔT if about <NUM> seconds, a false trip is avoided, but if the acceleration threshold is exceeded for any time, the safety brake deployment may occur in some embodiments. The predetermined time period, ΔT, is sufficient to filter out unwanted safety brake actuation, but sufficient to meet code requirements.

Referring now to <FIG>, a counterweight <NUM> is shown during a "jump" condition. As shown, slack in the cable <NUM> connecting the counterweight <NUM> and the elevator car <NUM> may be present due to various reasons. Upon tensioning of the cable <NUM>, the counterweight <NUM> may cause the safety brake <NUM>, in the engaged and braking condition, to reset due to movement of the elevator car <NUM> upward. The forces associated with such a process are illustrated. The aforementioned process is described as a false safety reset. Equipment of the electronic safety actuator <NUM>, such as an accelerometer, can study shock responses in the elevator car over time, and can mitigate conditions that would result in their undesirable engagement based on characteristics that are known to be associated with a false reset.

The embodiments described herein employ technology of the electronic safety actuator <NUM> to determine whether a velocity or acceleration is attributed to an actual free fall event or instead if a false trip or false reset condition is present. Additionally, the elevator system dynamically modifies the algorithms and parameters associated with brake actuation and resetting to reduce the likelihood of false trips and resets. Periodic reports can be sent to the customer and/or to a remote office to keep track of electronic safety actuator performance, which allows customer input into false trip and reset parameter modification.

The system and methods described herein reduce the likelihood of unwanted actuation and/or resetting of safety brakes using technology associated with electronic safety actuators. Such a problem may be present for numerous reasons. This is particularly problematic in countries where power outages occur regularly, thereby causing false trips in many cases. In certain countries, power outages may occur more than <NUM> times a day.

Embodiments may be implemented using one or more technologies. In some embodiments, an apparatus or system may include one or more processors, and memory storing instructions that, when executed by the one or more processors, cause the apparatus or system to perform one or more methodological acts as described herein. Various mechanical components known to those of skill in the art may be used in some embodiments.

Embodiments may be implemented as one or more apparatuses, systems, and/or methods. In some embodiments, instructions may be stored on one or more computer program products or computer-readable media, such as a transitory and/or non-transitory computer-readable medium. The instructions, when executed, may cause an entity (e.g., a processor, apparatus or system) to perform one or more methodological acts as described herein.

Claim 1:
A method of avoiding inadvertent resetting of a safety brake (<NUM>) of an elevator system (<NUM>), the method comprising:
obtaining data with at least one sensor associated with an electronic safety actuator (<NUM>); and characterized in that the method further comprises:
determining whether resetting of a safety brake (<NUM>) is made based on an algorithm that compares the data obtained by the sensor(s) and a threshold condition, resetting of the safety brake (<NUM>) occurring if the threshold condition is exceeded for equal to or greater than a predetermined amount of time.