阅读说明：本技术 紧急终端停止系统 (Emergency terminal stop system ) 是由 P·赫克尔 J·伦克 于 2020-12-04 设计创作，主要内容包括：提供有一种用于电梯系统的紧急终端停止系统,该紧急终端停止系统包括：传感器,其配置成确定与在电梯井道内移动的电梯轿厢的运动有关的数据；至少一个电梯制动器,其配置成使电梯轿厢的运动暂停；至少一个电梯安全钳装置,其设于电梯轿厢上；以及至少一个缓冲器,其设于井道的下部部分处。控制器配置成：从传感器接收与电梯轿厢的运动有关的数据；关于距正常电梯轿厢行进的终端极限的距离监测电梯轿厢的当前速率；检测电梯轿厢的异常速率；响应于所检测的异常速率而激活至少一个电梯制动器；继激活主电梯制动器之后,监测电梯轿厢的当前加速度；检测电梯轿厢的异常加速度；以及响应于所检测的异常加速度而激活电梯安全钳装置。(There is provided an emergency end stop system for an elevator system, the emergency end stop system comprising: a sensor configured to determine data related to movement of an elevator car moving within an elevator hoistway; at least one elevator brake configured to halt movement of the elevator car; at least one elevator safety gear device arranged on the elevator car; and at least one buffer provided at a lower portion of the hoistway. The controller is configured to: receiving data from a sensor relating to movement of the elevator car; monitoring a current velocity of the elevator car with respect to a distance from a terminal limit of normal elevator car travel; detecting an abnormal velocity of the elevator car; activating at least one elevator brake in response to the detected abnormal rate; monitoring a current acceleration of the elevator car subsequent to activating the primary elevator brake; detecting abnormal acceleration of the elevator car; and activating an elevator safety gear device in response to the detected abnormal acceleration.)

1. An emergency end stop system (30) for an elevator system (1), the emergency end stop system (30) comprising:

a sensor (20) configured to determine data related to movement of an elevator car (4) moving within an elevator hoistway (2);

at least one elevator brake (12) configured to halt the motion of the elevator car (4);

at least one elevator safety gear device (22) provided on the elevator car (4);

at least one buffer (24) provided at a lower portion (2a) of the hoistway (2); and

a controller (14) configured to:

-receive data from the sensor (20) relating to the movement of the elevator car (4);

-monitoring the current velocity of the elevator car (4) in relation to the distance from the terminal limit of normal elevator car (4) travel;

-detecting an abnormal velocity of the elevator car (4);

-activating the at least one elevator brake (12) in response to the detected abnormal rate;

-subsequent to activating the at least one elevator brake (12), monitoring a current acceleration of the elevator car (4);

-detecting an abnormal acceleration of the elevator car (4);

-activating the elevator safety gear device (22) in response to the detected abnormal acceleration.

2. The emergency end stop system (30) of claim 1 wherein the controller (14) is configured to detect an abnormal velocity by monitoring whether the current velocity of the elevator car (4) for the determined direction of travel of the elevator car (4) and the determined current position of the elevator car (4) is below a threshold value.

3. Emergency end stop system (30) according to claim 1 or 2, wherein the controller (14) is configured to monitor the current acceleration over a defined period of time (t) subsequent to activating the at least one elevator brake (12).

4. The emergency end stop system (30) of any of claims 1 to 3 wherein the controller (14) is configured to detect the abnormal acceleration by determining whether the current acceleration is greater than or equal to a threshold acceleration.

5. The emergency end stop system (30) of any preceding claim, wherein the controller (14) is configured to detect the abnormal acceleration by monitoring whether the current acceleration of the elevator car (4) for the determined direction of travel of the elevator car (4) and the determined current position of the elevator car (4) is below a threshold value.

6. The emergency end stop system (30) of any preceding claim wherein the at least one bumper (24) is an elastomeric bumper.

7. An elevator system (1) comprising:

a hoistway (2) extending between a plurality of landings (16);

an elevator car (4) configured for movement along the hoistway (2) between the plurality of landings (16); and

the emergency end stop system (30) of any of claims 1 to 8 wherein the at least one buffer (24) is provided at a lower end (2a) of the hoistway (2) below the elevator car (4).

8. The elevator system (1) of claim 9, further comprising a counterweight (18) and at least one second buffer (26) disposed below the counterweight (18).

9. A method (100, 101) for operating an emergency terminal stop system (30), the method comprising the steps of:

a) monitoring the current velocity of the elevator car (4) with reference to the distance from the terminal limit of normal elevator car (4) travel;

b) detecting an abnormal velocity of the elevator car (4);

c) activating an elevator brake (12) in response to the detected abnormal rate;

d) monitoring a current acceleration of the elevator car (4) subsequent to activating the elevator brake (12);

e) -detecting an abnormal acceleration of the elevator car (4);

f) applying an elevator safety gear device (22) when said monitored acceleration is determined to be abnormal.

10. The method (100, 101) according to claim 9, wherein step a) further comprises:

-determining a direction of travel of the elevator car (4); and

-determining the current position of the elevator car (4) relative to a lower terminal limit (TU) or an upper Terminal Limit (TL).

11. The method (100, 101) of claim 10, wherein step b) comprises monitoring whether the current velocity of the elevator car (4) is below a threshold value for the determined direction of travel and the determined current position.

12. The method (100, 101) according to any one of claims 9 to 11, wherein step e) comprises determining whether the current acceleration is greater than or equal to a threshold acceleration.

13. The method (100, 101) according to any one of claims 9-11, wherein step e) comprises determining whether the current acceleration is increasing.

14. The method (100, 101) according to any one of claims 9-13, wherein step e) comprises monitoring the current acceleration over a defined period of time (t) subsequent to activating the elevator brake (12).

15. The method (100, 101) according to any one of claims 10 to 14, further comprising the step of

c1) -if no abnormal speed is detected, determining whether the elevator car (4) is located in an upper or lower terminal limit zone; and the number of the first and second electrodes,

wherein step d) further comprises: monitoring the current acceleration of the elevator car (4) when the elevator car is in the upper terminal limit zone or the lower terminal limit.

Technical Field

The present disclosure relates to an emergency terminal stop system, and to a method of operating an emergency terminal stop system.

Background

Elevator systems typically include an elevator car that moves within a hoistway between a plurality of landings. The elevator car is guided by a track provided in the hoistway.

The elevator system may include one or more buffers mounted at a base of the elevator hoistway below the elevator car and configured to stop the elevator car if the elevator car moves downward below its normal travel limit (i.e., beyond a lower landing of the hoistway). For elevator systems that include a counterweight, one or more bumpers may also be provided in the base of the hoistway below the counterweight, providing a safe stop for the counterweight. A buffer may also be provided at an upper portion of the hoistway.

Various types of dampers are known, such as spring dampers, elastomer dampers, and oil dampers. Specifications vary around the world, but generally, buffers are rated in terms of elevator operating speed and elevator size. For a given elevator system, the buffer has a rated speed, which is the maximum speed that can withstand an elevator car impact. Traditionally, oil buffers have been used on elevators traveling at elevated (or higher, i.e., rated) velocities because these oil buffers are capable of absorbing the energy of the higher velocity impacts.

Generally, movement of the elevator car is monitored and an Emergency Terminal Stop (ETS) function activates the elevator brake when abnormal movement is detected indicating travel exceeding a predetermined lower terminal limit (lower limit of normal travel) or a predetermined upper terminal limit (upper limit of normal travel), wherein the objective is to slow down the elevator car (and counterweight (if provided)) to the rated speed of the buffer prior to the impact.

For example, if the elevator car is traveling downward faster than the threshold velocity for a given distance from the lower terminal limit, this indicates that the elevator car will travel beyond the lower terminal limit and impact the buffer too quickly. Similarly, where the elevator system includes a counterweight, if the elevator car is traveling upwards faster than the threshold rate by a given distance from the upper terminal limit, this indicates that the counterweight will travel beyond the lower terminal limit and impact the counterweight buffer too quickly and/or the elevator car may impact the upper buffer. In both cases, the elevator brake is activated in order to decelerate the downward movement of the elevator car (and counterweight) to or below the nominal velocity of the respective buffer.

In some situations, the elevator car continues to accelerate in the time between the detection of the abnormal motion and the activation of the brake. In this case, the action of the brake may not be sufficient to sufficiently decelerate the elevator car or counterweight prior to impact with the buffer.

Therefore, there is a need to improve elevator emergency end stop systems.

Disclosure of Invention

According to a first aspect of the present disclosure, there is provided an emergency end stop system for an elevator system, the emergency end stop system comprising: a sensor configured to determine data related to movement of an elevator car moving within an elevator hoistway; at least one elevator brake configured to halt movement of the elevator car; at least one elevator safety gear device (or called elevator safety gear device) arranged on the elevator car; and at least one buffer provided at a lower portion of the hoistway. The controller is configured to: receiving data from a sensor relating to movement of the elevator car; monitoring a current velocity of the elevator car with respect to a distance from a terminal limit of normal elevator car travel; detecting an abnormal velocity of the elevator car; activating at least one elevator brake in response to the detected abnormal rate; monitoring a current acceleration of the elevator car subsequent to activating the primary elevator brake; detecting abnormal acceleration of the elevator car; and activating an elevator safety gear device in response to the detected abnormal acceleration.

The controller may be configured to determine a car current velocity of the elevator car from data received from the sensor. The controller may be configured to determine the current acceleration of the elevator car from data received from the sensor.

The elevator brake may be provided in the drive system of the elevator system. The elevator brake may be an overspeed governor (governor), e.g. a mechanical overspeed governor or an electrically operated overspeed governor.

The controller may be configured to detect the abnormal velocity by monitoring whether a current velocity of the elevator car for the determined direction of travel of the elevator car and the determined current position of the elevator car is below a threshold value.

The controller may be configured to determine a direction of travel of the elevator car. The controller may be configured to determine a current position of the elevator car relative to the lower terminal limit and/or the upper terminal limit.

The controller may be configured to perform a zone check of whether the abnormal rate is not detected. The zone check may include determining whether the elevator car (or counterweight) is in a zone near one of the terminal limits, in other words, near the upper terminal limit TU or the lower terminal limit TL. The zone check may include determining whether the elevator car (or counterweight) is approaching one of the buffers.

The zone check may include determining whether the elevator car (or counterweight) is in the upper or lower terminal limit zone. The upper or lower terminal limit zone may be defined by a predetermined distance Z from the upper or lower terminal limit TU or TL.

The controller may be configured to: monitoring the current acceleration of the elevator car when the elevator car is in a terminal limit zone (an upper terminal limit zone or a lower terminal limit zone), and detecting the abnormal acceleration of the elevator car; and activating an elevator safety gear device in response to the detected abnormal acceleration.

The controller may be configured to monitor the current acceleration over a defined period of time subsequent to activation of the brake. The period may be in the range of 200ms to 800 ms. The period may be in the range of 200ms to 700 ms. The period may be in the range of 300ms to 600 ms. The period may be in the range of 300ms to 500 ms.

The controller may be configured to monitor the current acceleration until the elevator car is at rest.

The controller may be configured to detect the abnormal acceleration by determining whether the current acceleration is greater than or equal to a threshold acceleration. The controller may be configured to detect the abnormal acceleration by determining whether the current acceleration is greater than or equal to zero m/s2 acceleration over the period of time. The controller may be configured to detect the abnormal acceleration by determining whether the current acceleration is increasing over a period of time.

The controller may be configured to detect abnormal acceleration by determining whether the monitored acceleration is constant or increasing over a period of time. The controller may be configured to detect the abnormal acceleration by determining that the elevator car is not decelerating over a defined period of time. The abnormal acceleration can be defined as an acceleration that increases over the period of time. The controller may be configured to detect the abnormal acceleration by determining that the elevator car has not decelerated above a threshold deceleration over a defined period of time.

The emergency end stop system may include a load sensor disposed on the elevator car. The emergency terminal stop system may include an upper terminal limit sensor configured to detect when the elevator car and/or counterweight reaches an upper terminal limit of normal elevator travel. The emergency terminal stop system may include a lower terminal limit sensor configured to detect when the elevator car and/or counterweight reaches a lower terminal limit of normal elevator travel.

The controller may be configured to detect the abnormal acceleration by monitoring whether a current acceleration of the elevator car for the determined direction of travel of the elevator car and the determined current position of the elevator car is below a threshold value.

The sensor may be configured to provide position and/or velocity data for the elevator car. The sensor may be a position sensor. The sensor may be a rate sensor. The sensor may be an acceleration sensor. The sensors may include position sensors and velocity sensors. The sensor may be provided on the elevator car. The sensor may be provided in the drive system of the elevator system.

The or each bumper may be a rubber bumper. The or each bumper may be an elastomeric bumper. The or each buffer may be a polyurethane buffer. The or each buffer may be an oil buffer. The or each bumper may be a spring bumper.

According to a further aspect, there is provided an elevator system comprising: a hoistway extending between a plurality of landings; an elevator car configured for movement along a hoistway between a plurality of landings; and an emergency end stop system as described above, wherein at least one buffer is provided at the lower end of the hoistway below the elevator car.

The or each bumper may be a rubber bumper. The or each bumper may be an elastomeric bumper. The or each buffer may be a polyurethane buffer. The or each buffer may be an oil buffer. The or each bumper may be a spring bumper.

At least one buffer may be provided below the elevator car. At least one buffer may be provided in the extension of the travel path of the elevator car.

The sensor may be a position sensor. The sensor may be a rate sensor. The sensors may include position sensors and velocity sensors. The sensor may be provided on the elevator car. The sensor may be provided in the drive system of the elevator system.

The elevator system may further comprise a counterweight and the at least one second buffer is disposed below the counterweight. At least one bumper may be provided in the extension of the travel path of the counterweight. The or each second damper may be an oil damper. The or each second damper may be a spring damper. The or each second buffer may be a rubber buffer. The at least one bumper may be an elastomeric bumper. The or each second buffer may be a polyurethane buffer.

According to a further aspect, there is provided a method for operating an emergency terminal stop system, the method comprising:

a) monitoring a current velocity of the elevator car with reference to a distance from a terminal limit of normal elevator car travel;

b) detecting an abnormal velocity of the elevator car;

c) activating an elevator brake in response to the detected abnormal rate;

d) subsequent to activating the elevator brake, monitoring a current acceleration of the elevator car;

e) detecting abnormal acceleration of the elevator car;

f) when the monitored acceleration is determined to be abnormal, an elevator safety gear device is applied.

The current velocity of the elevator car can be determined by a velocity sensor provided on the elevator car. The current velocity of the elevator car can be determined by calculation using data from position sensors on the elevator car. The current velocity of the elevator car can be determined by a sensor provided in the drive system of the elevator car.

Step a) may comprise determining a direction of travel of the elevator car. Step a) may comprise determining the current position of the elevator car relative to the lower terminal limit and/or the upper terminal limit.

When the elevator car is traveling upwards, the current position relative to the upper terminal limit is determined. When the elevator car is traveling downwards, the current position relative to the lower terminal limit is determined.

Step b) may comprise monitoring whether the current velocity of the elevator car for the determined direction of travel and the determined current position is below a threshold value.

The step of monitoring the current velocity of the elevator car may include determining a direction of travel of the counterweight. The step of monitoring the current velocity of the elevator car may include determining a direction of travel of the counterweight. The step of monitoring the current velocity of the elevator car may comprise determining a direction of travel of the counterweight relative to the lower terminal limit and/or the upper terminal limit.

The method may comprise step c 1): performing zone checking if no abnormal rate is detected in step b). Step c1) may comprise determining whether the elevator car (or counterweight) is in a zone near one of the terminal limits, in other words, near the upper terminal limit TU or the lower terminal limit TL. Step c1) may include determining whether the elevator car (or counterweight) is approaching one of the buffers.

Step c1) may comprise: it is determined whether the elevator car (or counterweight) is in the upper or lower terminal limit zone. The upper or lower terminal limit zone may be defined by a predetermined distance Z from the upper or lower terminal limit TU or TL.

Step d) may comprise: when the elevator car is in the terminal limit zone (upper terminal limit zone or lower terminal limit zone), the current acceleration of the elevator car 4 is monitored.

Step e) may comprise: it is determined whether the current acceleration is greater than or equal to a threshold acceleration.

Step e) may comprise: it is determined whether the deceleration of the elevator car is above a deceleration threshold.

Step e) may comprise: it is determined whether the current acceleration is greater than or equal to zero. Step d) may comprise: it is determined whether the current acceleration is greater than or equal to zero.

The abnormal acceleration can be defined as greater than or equal to zero. The abnormal acceleration can be defined as greater than zero.

Step e) may comprise: it is determined whether the current acceleration is increasing. Step e) may comprise: it is determined whether the current acceleration is increasing over a certain period of time.

Step e) may comprise: it is determined whether the acceleration is constant or increasing over a certain period of time. Step e) may comprise: it is determined that the elevator car is not decelerating over the defined period of time.

The abnormal acceleration can be defined as an acceleration that increases over the period of time.

Step e) may comprise: the current acceleration is monitored over a defined period of time following activation of the primary elevator brake.

Step e) may comprise: the current acceleration is monitored until the elevator car has stopped. The period may be in the range of 200ms to 800 ms. The period may be in the range of 200ms to 700 ms. The period may be in the range of 300ms to 600 ms. The period may be in the range of 300ms to 500 ms.

Step e) may comprise: the load of the elevator car is monitored. Step e) may comprise: the acceleration is always determined to be abnormal when the monitored load of the elevator car is above a threshold load.

Step e) may comprise: a buffer toward which the elevator car is traveling is identified. Step e) may comprise: the current speed of the elevator car is checked against the nominal speed of the buffer. Step e) may comprise: when the current speed is lower than the rated speed, it is determined that the acceleration is not abnormal.

The system and method described above provide a reliable and economical solution that can be easily retrofitted into existing elevator systems.

Drawings

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

fig. 1 illustrates an elevator system according to an example of the present disclosure;

fig. 2 shows an elevator system according to another example of the present disclosure;

fig. 3 illustrates a method for operating an emergency end stop system according to an example of the present disclosure;

FIG. 4 shows an example of a rate threshold distribution (or curve, profile) that can be used in the method of FIG. 3;

fig. 5 illustrates a method for operating an emergency terminal stop system according to another example of the present disclosure; and

fig. 6 shows an example of a velocity threshold distribution that can be used in the method of fig. 5.

Detailed Description

Fig. 1 shows a first example of an elevator system 1, the elevator system 1 comprising a hoistway 2 and an elevator car 4, the elevator car 4 traveling along guide rails 6 within the hoistway 2. The elevator car 4 is movably suspended by a tension member 8, e.g. a rope or belt. The tension member 8 is connected to a drive system 10, the drive system 10 is configured to drive the tension member 8 to move the elevator car 4, and the drive system 10 includes a brake 12. The drive system 10 may be any type of conventional drive, such as, but not limited to, a traction drive. The elevator car 4 moves between a plurality of landings 16. For ease of understanding, only the upper and lower landings 16 are depicted in FIG. 1.

The elevator system 1 also comprises a controller 14. The controller 14 is depicted in the upper portion 2b of the hoistway in fig. 1. However, it will be appreciated that the controller 14 can be located in any suitable location within or near the hoistway 2. The term controller 14 is also understood to include a plurality of controller units provided in the elevator system 1.

In the example of fig. 1, the sensor 20 is provided on the elevator car 4. The sensor 20 is configured to monitor movement of the elevator car 4. The sensor 20 is configured to monitor the current position and/or current velocity of the elevator car 4. Data from the sensor 20 is sent to the controller 14.

The sensor 20 can be any suitable sensor configured to provide data related to the current position and/or current velocity of the elevator car 4. The sensor 20 may be a position sensor 20, for example, an absolute position determination sensor or an incremental position determination sensor. Data relating to the current position of the elevator car 4 is transmitted to the controller 14, and the controller 14 then uses the position data to determine the current velocity of the elevator car 4. The sensor 20 may include a velocity sensor in addition to or in place of a position sensor. Where only a rate sensor is provided, the controller 14 determines position information from the rate data.

The elevator car 4 is also provided with one or more elevator safety gear devices 22 (also referred to as safety devices), which elevator safety gear devices 22 clamp onto the elevator guide rails 4 when activated.

The buffer 24 is provided in a lower portion 2a of the hoistway 2, and the lower portion 2a is an area below the lower landing 16. The lower portion 2a of the hoistway 2 is sometimes referred to as a hoistway pit. The buffer 24 is located below the elevator car 4 below the extension of the travel path of the elevator car 4. The buffer 24 is provided at a distance D below the lower terminal limit TL of the elevator car 4. Although one bumper 24 is shown in fig. 1, it will be appreciated that in other examples, two or more bumpers 24 may be provided.

The upper terminal limit TU of the elevator car 4 is shown at the upper part 2b of the hoistway 2.

Emergency end stop system 30 includes sensor 20, controller 14, brake 12, elevator safety gear device 22, and buffer 24.

Fig. 2 shows a second example of an elevator system 1. The same components as those described above are provided with the same reference numerals.

In fig. 2, the elevator system 1 also comprises a counterweight 18, which counterweight 18 is parallel to the elevator car 4 and moves in the opposite direction to the elevator car 4. The counterweight 18 runs along a guide rail 19 and is movably suspended to the second end of the tension member 8.

The elevator system 1 of fig. 2 includes a second buffer 26, the second buffer 26 being disposed below the counterweight 18 below an extension of the travel path of the counterweight 18. Although one second buffer 26 is shown in fig. 2, it will be appreciated that in other examples, two or more second buffers 26 may be provided.

Fig. 2 also shows two upper buffers 24a and 26a provided in the upper portion 2b of the hoistway 2 and aligned with the travel path of the elevator car 24 and counterweight 18. The upper buffers 24a, 26a are provided to decelerate the elevator car 4/counterweight 18 in case the car 4/counterweight 18 travels beyond the upper terminal limit TU. This may occur, for example, in situations where the drive system 10 is powered down and the elevator car 4 has a relatively small load (e.g., no passengers). In this situation, the counterweight 18 will cause the elevator car 4 to accelerate upwards towards the upper buffer 24 a.

In the opposite situation to that previously described, i.e. in the case where the heavily loaded elevator car 4 is accelerating downwards, it will be appreciated that the counterweight 18 is accelerating upwards towards the upper buffer 26 a.

The elevator system 1 of fig. 2 may also include a load sensor 32 disposed on the elevator car 4, the load sensor 32 configured to monitor a load on the elevator car 4. It will be appreciated that in the example of fig. 1, a load sensor 32 can also be provided.

The elevator system 1 of fig. 2 may also comprise an upper terminal limit sensor 34a and a lower terminal limit sensor 34 b. The upper and lower terminal limit sensors 34a, 34b are configured to detect when the elevator car 4 reaches the upper terminal limit TU or the lower terminal limit TL. It will be appreciated that in the example of fig. 1, terminal limit sensors 34a, 34b can also be provided.

The emergency terminal stop system 30 of fig. 2 includes: sensor 20, controller 14, brake 12; an elevator safety gear device 22, and buffers 24, 24a, 26 b.

The emergency end stop system 30 may also include a load sensor 32 (when provided). Similarly, the emergency end stop system 30 may also include an upper end limit sensor 34a and a lower end limit sensor 34 b.

In other examples (not shown), the sensor 20 may be provided on another component within the elevator system 1. For example, the sensor 20 may be disposed within the drive system 10 and configured to monitor movement of a component within the drive system 10. The current velocity of the elevator car 4 can be determined and monitored by the controller 14 using data from such sensors 20.

In other examples (not shown), the elevator system 1 comprises a drive system 10 operating without the tension member 8, such as e.g. a hydraulic drive or a linear drive.

Fig. 3 shows an exemplary method 100 for operating the emergency end stop system 30 as described in the examples described above.

In step 110, the controller 14 detects that the elevator car 4 is in motion. This can be done by monitoring the signal from the sensor 20. Alternatively, the controller 14 can use any other suitable means, such as, but not limited to, using data provided by an accelerometer provided on the elevator car 4. The accelerometer may be provided as part of the sensor 20 described above, or as an additional component provided separately on the elevator car 4.

Once the elevator car 4 is in motion, the controller 14 monitors the current velocity of the elevator car 4 in step 120. The controller 14 receives data from sensors 20 relating to the position and/or velocity of the elevator car 4. This data can be used directly or as a basis for calculating the current rate. The controller 14 also determines the direction of travel of the elevator car 4. In other words, a determination is made as to whether the elevator car 4 is traveling upward or downward.

In step 130, the controller 14 compares the determined current velocity of the elevator car 4 with known data for the elevator system 1 to determine if the current velocity is abnormal. An exemplary method for determining an abnormal rate is described below.

The controller 14 determines whether the elevator car 4 is traveling downwards or upwards. This determination can be made using data from the sensors 20 and, optionally, can be made from data received from the terminal limit sensors 34a, 34 b.

Both the distance D between the buffer 24 and the lower terminal limit TL and the nominal rate R of the buffer 24 are known. From this data, a threshold velocity profile for downward travel of the elevator car 4 is defined with respect to the distance from the lower terminal limit TL. The threshold velocity profile represents the normal deceleration of the elevator car 4.

An exemplary velocity threshold distribution is shown in fig. 4, where the distance to the lower terminal limit TL is represented on the x-axis. The lower terminal limit TL is defined as zero on the x-axis and the buffer 24 is located at a distance-D from the lower terminal limit TL. The velocity of the elevator car 4 is represented on the y-axis, where R is the nominal velocity of the buffer 24. When the elevator car 4 is determined to be traveling downward in the hoistway 2, the current velocity of the elevator car 4 is monitored against a velocity threshold profile. If the current speed is still below the greater of the threshold line and the rated speed R, the elevator car 4 is expected to be able to decelerate to or below the rated speed R. In other words, if the elevator car 4 impacts the buffer, the buffer 24 will be in its safe operating range. In this case, the rate is determined to be no anomaly.

However, if the current velocity exceeds the threshold value for a given distance from the lower terminal limit TL and the current velocity is higher than the nominal velocity R (i.e. in the shaded area indicated by a), it will not be possible for the elevator car 4 to decelerate below the nominal velocity R before the elevator car 4 hits the buffer 24. In this case, the controller 14 determines that the rate is abnormal.

This same profile can be used to determine an abnormal rate when the elevator car is traveling upward.

Although one example is described above, alternative methods of determining an abnormal rate may be used.

If it is determined that the velocity of elevator car 4 is not abnormal, controller 14 continues to monitor the current velocity of elevator car 4, i.e., repeats steps 120 and 130.

If it is determined that elevator car 4 is traveling at an abnormal rate, elevator brake 12 is activated in step 140.

In step 150, after brake 12 is activated, controller 14 monitors the current acceleration of elevator car 4. The controller 14 receives data from the sensors 20 relating to the position and/or velocity of the elevator car 4. This data can be used directly for calculating the current acceleration or as a basis for calculating the current acceleration. The controller 14 can also determine the direction of travel of the elevator car 4. In other words, a determination is made as to whether the elevator car 4 is traveling upward or downward.

In step 160, the controller 14 compares the determined current acceleration of the elevator car 4 with known data for the elevator system 1 to determine whether the current acceleration is abnormal. The aim is to identify a situation in which the elevator car 4 is not slowed sufficiently by the brake 12.

The controller 14 determines whether the current acceleration is abnormal, wherein abnormal acceleration means that the elevator car 4 is likely not slowing down sufficiently before the elevator car 4 reaches the buffer 24, 24a towards which it is traveling. If the elevator car continues to accelerate, this means that the elevator car 4 is continuing to accelerate and therefore the elevator car 4 will arrive at the buffer 24 at an even higher velocity, which will be a larger overload on the buffer 24.

An exemplary method for determining abnormal acceleration is described below.

In step 160, the detection of abnormal acceleration may include determining whether the current acceleration is greater than or equal to a threshold acceleration. Additionally or alternatively, the detection of abnormal acceleration includes determining whether the current acceleration is increasing.

Step 160 may include: it is determined whether the deceleration of the elevator car 4 is above a deceleration threshold. In this situation, after triggering the brake 12, it is expected that the elevator car 4 will decelerate sufficiently for a certain period of time to reduce the current velocity of the elevator car 4 to a value below the nominal buffer velocity R. Thus, deceleration (i.e., rate reduction) can be monitored to detect abnormal behavior. If it is determined that the deceleration is below the deceleration threshold, in other words, for whatever reason, not decelerating sufficiently fast, this will indicate that the elevator car 4 (or counterweight 18) may collide with the buffer at a higher rate than the nominal buffer rate R. In this case, the acceleration is determined to be abnormal.

Controller 14 may determine whether elevator car 4 is traveling downward or upward. This determination can be made using data from the sensors 20 and optionally from data received from the end limit sensors 34a, 34 b. The determined direction may be used in the determination of the abnormal acceleration.

In some situations an abnormal load in the elevator car 4 may cause an abnormal acceleration, e.g. a heavily loaded elevator car 4 may continue to accelerate if the elevator car 4 is moving downwards, or the counterweight 18 may cause an upward acceleration of the elevator car 4 if the elevator car 4 is moving upwards with a small load. Thus, step 160 may also include monitoring the load of the elevator car 4 using the load sensor 32 and determining an abnormal acceleration based on the determined load and direction of travel. When the elevator car 4 is moving downwards and the monitored load of the elevator car 4 is above the upper threshold load (i.e. the elevator car 4 is heavily loaded), the acceleration is determined to be abnormal. When the elevator car 4 is moving upwards and the monitored load of the elevator car 4 is below the lower threshold load, the acceleration is determined to be abnormal.

Step 160 may also include: the data from the terminal limit sensors 34a, 34b are used to determine whether the elevator car 4 has reached the upper terminal limit TU or the lower terminal limit TL. A determination of an acceleration anomaly is made if the current velocity of the elevator car 4 is higher than the nominal velocity R of the buffer towards which the elevator car 4 is traveling when the elevator car 4 passes the upper terminal limit TU or the lower terminal limit TL.

Step 160 may also include: data from the end limit sensors 34a, 34b is used to determine whether the counterweight 18 has reached the upper end limit TU or the lower end limit TL. A determination of an acceleration anomaly is made if the current velocity of counterweight 18 is higher than the nominal velocity R of the buffer toward which counterweight 18 is traveling when counterweight 18 passes upper terminal limit TU or lower terminal limit TL.

It will be appreciated that step 160 may include one or more of the ways of determining abnormal acceleration outlined above.

In step 160, the acceleration of the elevator car 4 may be monitored until the elevator car 4 becomes stationary. Alternatively, the acceleration of the elevator car 4 can be monitored over a defined time period t, wherein the time period t depends on the activation time of the brake 12. The acceleration of the elevator car 4 should be monitored for a period t at least as long as the activation time of the brake 12 in order to determine whether the action of the brake 12 alone is sufficient to slow down the elevator car 4.

If the acceleration is determined to be without an anomaly, controller 14 continues to monitor the current acceleration of elevator car 4, i.e., repeats steps 150 and 160/260. The monitoring of the acceleration continues until the elevator car 4 is stationary or the time period t has expired.

If the controller 14 determines that the acceleration of the elevator car 4 is abnormal, the controller 14 activates the safety gear device 22 in addition to the brake 12 in step 170. The safety gear device 22 reacts faster than the brake 12 and therefore the velocity of the elevator car 4 decreases more rapidly.

Fig. 5 shows another exemplary method 101 for operating the emergency end stop system 30 as described in the examples described above. Method 101 is a modified version of the method described above with reference to fig. 3 including steps 110, 120, 130, 140, 150, 160, and 170 as described above.

In method 101, if the current rate is determined to be not anomalous in step 130, an additional step 135 is performed. Step 135 is a zone check in which the controller 14 determines whether the elevator car 4 is in a zone near one of the terminal limits, in other words, near the upper terminal limit TU or the lower terminal limit TL and thus also near one of the buffers 24, 24a, 26 a.

The upper and lower terminal limit zones are defined by a predetermined distance Z from the upper terminal limit TU or the lower terminal limit TL, which is determined by the characteristics of the elevator system 1. This is shown in fig. 6. The shaded area B represents the situation when it is determined that the velocity is not abnormal (i.e. not within zone a), but the elevator car 4 is less than the distance Z from the terminal limit. Thus, the distance Z is defined as the distance where the threshold rate is equal to the nominal rate R of the buffers 24, 24a, 26 a. Thus, the distance Z is determined by the threshold rate for the "abnormal rate" and the nominal rate of the buffer.

If the elevator car 4 is in the terminal limit zone (upper terminal limit zone or lower terminal limit zone), the controller 14 monitors the current acceleration of the elevator car 4 in step 150. This allows the system to detect abnormal accelerations approaching the upper or lower terminal limit TU or TL even if the current velocity of the elevator car 4 has not exceeded the nominal velocity R. This will detect a situation where the elevator car 4 performs a normal run starting from a landing adjacent to the terminal landing, but is moving in the wrong direction, e.g. when the elevator car 4 starts to run "upwards" from the second landing to the last landing, but instead upwards, the elevator car 4 moves downwards. In this case the elevator car 4 will start at velocity zero, but if the elevator car 4 will exceed the buffer velocity R, it may be too close to the terminal limit to be stopped by activating only the brake 12. The emergency end stop system 30 provides countermeasures, the emergency end stop system 30 detects abnormal acceleration when the elevator car 4 is moving towards the end limit, and activates the safety gear device 22.

The following steps 160 of determining abnormal acceleration and 170 of applying the safety gear device when appropriate are as outlined above.

If the elevator car 4 is not in the terminal limit zone, the controller 14 continues to monitor the current velocity of the elevator car 4, i.e. steps 120 and 130 are repeated.

Those skilled in the art will appreciate that the present disclosure has been illustrated by the description of one or more specific aspects of the disclosure, but is not limited to these aspects; many variations and modifications are possible within the scope of the appended claims.