GB2525682A

GB2525682A - An elevator installation

Info

Publication number: GB2525682A
Application number: GB1407839.8A
Authority: GB
Inventors: Peter Collins; John Curzon
Original assignee: ENSOTA Ltd
Current assignee: ENSOTA Ltd
Priority date: 2014-05-02
Filing date: 2014-05-02
Publication date: 2015-11-04
Also published as: GB201407839D0; CN105035897B; CN105035897A

Abstract

An elevator installation comprising an elevator car 20 with an optical door sensor 100 and a cleaning unit 40 mounted in an elevator shaft 12, which cleans the sensor 100 as it passes. There may be an elevator controller that controls the speed of the car, which may be less than or equal to a limit clearing speed. The cleaning unit 40 may be mounted in a terminal portion of the elevator shaft 12 so that the cleaning takes place during a starting or stopping phase. The cleaning unit 40 may be selectively deployed from a rest configuration to a deployed configuration by means of a cam (60 fig. 5). The sensor 100 may comprise an emitter 101 and a receiver 105, each with its own cleaning unit 40. There may be a cleaning unit controller which initiates the cleaning operation and may monitor the service time of the car, the journey time of the car, the count of the car stops completed, the count of the car journeys and/or the distance travelled by the car. There may be a test module which may cause the cleaning controller to initiate a cleaning operation based on the output. The cleaning unit 40 can reduce the debris on the sensor 100 and can increase its performance.

Description

AN ELEVATOR INSTALLATION

The invention relates to an elevator installation, in particular an elevator installation comprising a cleaning unit mounted in a shaft of the elevator installation and configured to clean an optical door sensor of an elevator car.

A typical elevator installation has an elevator shaft in which there is a number of predetermined stops corresponding to the floors of a building, and an elevator car movable within the elevator shaft. The elevator car typically has one or two doors, and the elevator shaft typically has a corresponding number of shaft doors at each stop.

Known elevator installations are provided with a number of sensors to ensure safe operation of the elevator installation, in particular the doors. An elevator car is typically provided with an optical door sensor for detecting the presence of an obstacle, such as a person or an object, in front of the elevator car doors. Known optical door sensors include break beam sensors that form a light curtain of infrared light outside of the elevator car doors (i.e. between the elevator car doors and the elevator shaft doors when the elevator car is at a stop). The optical door sensors may have an array of emitters for emitting light signals, and an array of receivers for detecting the light signals. The optical door sensor typically determines that there may be an obstacle in front of the elevator car doors when an emitted light signal is not detected by a receiver.

The operation of such an elevator installation depends on whether the optical door sensor determines the presence of an obstacle or not. For example, confirmation that no obstacle is present is typically required before an elevator car can begin to move, and the elevator car doors may be prevented from closing if the optical door sensor determines that an obstacle is present. Accordingly, the optical door sensor can essentially shut down the elevator installation, and therefore access to a building, if it determines that an obstacle is present.

The performance of the optical door sensor may depend on the operating conditions of the elevator installation. In a particularly dirty or dusty environment, material may build up on the optical door sensor that may partially or totally occlude light signals at the emitter and/or the receiver. A build-up of material may therefore prevent a light signal emitted by the emitter from being detected by the receiver, causing the optical door sensor to incorrectly determine that an obstacle is present, and thereby preventing the doors from closing and the elevator car from moving. A build-up of material on the optical door sensor or the deterioration of other operating conditions of the optical door sensor may therefore cause the elevator installation to be temporarily taken out of service.

Whilst it may be possible to manually clean the optical door sensor to resume normal service, this can be an awkward procedure and maintenance personnel may not be adequately trained. Further, it is often deemed necessary to call out maintenance personnel to clean the optical door sensor, which can be expensive and can result in delays to service re-entry.

Further, the applicant has found that maintenance personnel frequently replace an optical door sensor under a false assumption that it is faulty, without considering cleaning it. A replacement sensor will typically allow normal service to resume, and so the assumption that the fault lay with the optical door sensor often remains unchallenged. Accordingly, elevator installations in dirty and/or dusty environments are particularly prone to being taken out of service, often resulting in the replacement of an optical door sensor, which can be expensive.

Further, the deterioration of the operating conditions of the optical sensor is typically only detected once it has failed to function properly, since an investigation as to the cause of failure may then be initiated.

It is therefore desirable to provide an improved elevator installation which may overcome the above problems.

According to an aspect of the invention there is provided an elevator installation comprising: an elevator car movable within an elevator shaft, the elevator car having an optical door sensor; and a cleaning unit mounted in the elevator shaft and configured to clean the optical door sensor in a cleaning operation as the optical door sensor passes the cleaning unit. Accordingly, the optical door sensor can be cleaned automatically by the cleaning unit as the elevator car passes the cleaning unit.

The cleaning unit may comprise a cleaning element for cleaning the optical door sensor. The cleaning element may be of any suitable type, for example, a brush, a cleaning pad, or an air blower.

The elevator installation may further comprise an elevator controller configured to control the speed of the elevator car in the elevator shaft. The elevator controller may be configured so that the speed of the elevator car during a cleaning operation is less than or equal to a limit cleaning speed. The limit cleaning speed may be predetermined. The limit cleaning speed may be set so that the cleaning operation is of a minimum duration. The limit cleaning speed may be set so that the elevator car does not move past the cleaning unit at excessive speed, which may damage the cleaning unit, the optical door sensor and/or the elevator car.

The cleaning unit may be mounted within a terminal portion of the elevator shaft in which the maximum operational speed of the elevator is less than or equal to a limit cleaning speed. Mounting the cleaning unit in the terminal portion of the elevator shaft may have the effect that in use cleaning operations take place exclusively during a starting phase or a stopping phase of the elevator car. Accordingly, the maximum operational speed of the elevator car in a cleaning operation may be less than or equal to the limit cleaning speed owing to the elevator car always being in a starting or stopping phase, as opposed to a limit being applied on the speed of the elevator car by the elevator controller solely for the purposes of the cleaning unit and/or a cleaning operation. Accordingly it may not be necessary to amend or update an elevator controller when modifying an elevator installation to include a cleaning unit. The upper terminal stop is typically the least frequently visited part of the elevator shaft.

Accordingly, mounting the cleaning unit in the upper terminal portion of the elevator shaft can mean that the average time interval between cleaning operations is maximised, which can be beneficial in extending the lifetime of the cleaning unit and/or optical door sensor.

The cleaning unit may be deployable from a rest configuration to a deployed configuration in which it is arranged to clean the optical door sensor in a cleaning operation as the optical door sensor passes the cleaning unit. In contrast, in the rest configuration, the cleaning unit is arranged so that the optical door sensor can pass the cleaning unit without being cleaned. Therefore the cleaning unit may only clean the optical door sensor when the cleaning unit is in the deployed configuration, which may improve the lifetime of the cleaning unit and/or the optical sensor by limiting wear.

The cleaning unit may be configured to move automatically from the deployed configuration to the rest configuration after a cleaning operation. In other words, the cleaning unit may be configured to be automatically un-deployed or retracted after a cleaning operation. The elevator installation may comprise a return mechanism which is configured to move the cleaning unit from the deployed configuration to the rest configuration. The return mechanism may comprise cooperating formations provided on the elevator car and the cleaning unit.

The cleaning unit may be configured so that it can be selectively deployed and selectively un-deployed. For example, the cleaning unit could be deployed and un-deployed upon request, or on the instruction of a control system.

The cleaning unit may comprise resilient support means arranged to accommodate movement of the cleaning unit whilst in the deployed configuration during a cleaning operation. For example, the cleaning unit may comprise a flexible support arm or a resilient support member between a cleaning element of the cleaning unit and the attachment or mounting point of the cleaning unit in the elevator shaft.

The elevator installation may comprise a cleaning sensor for determining when a cleaning operation has taken place. For example, the cleaning sensor may be a pressure sensor or a strain gauge arranged to sense the engagement of the optical door sensor and the cleaning unit,.

The optical door sensor may comprise an emitter for emitting a light signal, and a receiver for detecting the light signal, and the elevator installation may comprise a cleaning unit for the emitter and a cleaning unit for the receiver. There may be an emitter array comprising a plurality of emitters, and a receiver array comprising a plurality of receivers.

The elevator installation may further comprise a cleaning controller for selectively initiating a cleaning operation. The cleaning controller may be configured to initiate a cleaning operation by deploying the cleaning unit and/or by calling the elevator car to move past the cleaning unit. The cleaning controller may be part of the elevator controller, or alternatively it may be separate from the elevator controller. The cleaning controller may be coupled to the elevator controller so that it can call the elevator car to move past the cleaning unit.

The cleaning controller may be configured to periodically initiate a cleaning operation.

The expression "periodically initiate a cleaning operation" is intended to mean that a cleaning operation is initiated regularly, but not necessarily based on regular intervals of elapsed time. For instance, a cleaning operation could be periodically initiated by monitoring the number of elevator car journeys and initiating a cleaning operation after a predetermined number (or threshold) of journeys, such as 50 journeys.

The cleaning controller may be configured to monitor at least one elevator operating parameter of the elevator installation and to initiate a cleaning operation based on the at least one elevator operating parameter, for instance, at a predetermined frequency.

Alternatively, a cleaning operation may be initiated when the at least one elevator operating parameter reaches a predetermined cleaning threshold. The at least one elevator operating parameter may be reset when a cleaning operation is initiated or when it is determined that a cleaning operation has taken place. For example, an elevator operating parameter relating to the number of car journeys completed may be reset to zero when a cleaning operation is initiated or determined to have taken place, even if the cleaning operation was initiated based on a different elevator operating parameter, such as elapsed time (e.g. elapsed time since the last cleaning operation).

The at least one elevator operating parameter may be selected from a group consisting of a service time of the elevator car, a journey time of the elevator car, a count of elevator car stops completed, a count of elevator door opening and/or closing operations completed, a count of elevator car journeys and a distance travelled by the elevator car. Further, the at least one elevator operating parameter may be a compound elevator operating parameter relating to a combination of the service time elevator car, a journey time of the elevator car, a count of elevator car stops completed, a count of elevator door opening and/or closing operations completed, a count of elevator car journeys and a distance travelled by the elevator car. For example, a compound elevator operating parameter may be calculated based on the number of elevator car stops in addition to the number of door opening and/or closing operations.

The elevator installation may further comprise a test module configured to test the optical door sensor. The cleaning controller may be configured to initiate a cleaning operation based on an output of the test module, for example when the test module determines that an operating margin of the optical door sensor is less than or equal to a margin limit. The test module may be configured to simulate a deterioration of the operating conditions of the optical door sensor and to determine whether the optical door sensor continues to function normally.

Deterioration of the operating conditions may be simulated by offsetting one or more sensor operating parameters relative to a baseline state of the optical door sensor in which it functions normally (i.e. in which a light signal from an emitter can be detected by a corresponding receiver). For example, a deterioration of the operating conditions may be simulated by reducing the light intensity of light signals emitter by the emitters, reducing the sensitivity (or gain ratio) of the receiver and/or introducing a noise signal by altering the signal-to-noise ratio by a predetermined amount. For example, the light intensity of light signals may be reduced by 20%. The test module may be configured to determine if the optical door sensor continues to function normally by determining whether a light signal from an emitter can be detected by a corresponding receiver. If the light signal cannot be detected, then it may be determined that the operating margin is less than or equal to a margin limit corresponding to the predetermined amount (e.g. a 20% reduction of the light intensity), and a cleaning operation may be initiated. If the light signal can be detected, then it may be determined that the operating margin is greater than or equal to the margin limit, and so a cleaning operation may not be initiated.

The test module may be configured to determine whether a cleaning operation has taken place. Accordingly, the test module and optical door sensor may form a cleaning sensor for determining that a cleaning operation has taken place. For example, the test module may be configured to detect that a cleaning operation has taken place by evaluating an output of the receiver. The test module may determine that a cleaning operation has taken placed when the output of the receiver indicates an increase in the light intensity of a light signal received thereon.

According to a further aspect of the invention there is provided a method of maintaining an optical door sensor of an elevator installation in accordance with any statement herein, the elevator installation comprising a cleaning controller for selectively initiating a cleaning operation, the method comprising: testing the optical door sensor; and initiating a cleaning operation based on an outcome of the test.

The invention will now be described, by way of example, with reference to the following drawings, in which: Figure 1 schematically shows an elevator installation according to an embodiment of the invention; Figure 2 schematically shows an elevator car of the elevator installation of Figure 1; Figure 3 shows a static cleaning unit; Figure 4 shows an air blower cleaning unit; Figure 5 shows a cam-operated cleaning unit; Figure 6 shows a further cam-operated cleaning unit; and Figure 7 shows a cleaning unit with a suspension suppoit.

Figure 1 shows an elevator installation 10 comprising an elevator shaft 12, an elevator car 20 having an optical door sensor 100, and a cleaning unit 40.

In this embodiment the elevator shaft 12 comprises three sets of shaft doors 14 for three corresponding floors 16 of a building.

The elevator car 20 comprises a carrying space 22 and a pair of elevator car doors 24.

The elevator car 20 is movable within the elevator shaft 12 between a number of predetermined stops corresponding to the floors 16 of the building. The upper and lower predetermined stops (or terminuses) are disposed within terminal portions 18 of the elevator shaft 12. The terminal portions 18 are portions of the elevator shaft 12 including the end of the elevator shaft 12, as will be described in more detail below. An elevator controller (not shown) is also provided for controlling movement of the elevator car 20 in the elevator shaft 12, in particular, for controlling the speed of the elevator car 20. The elevator controller may be housed in the elevator car 20, elsewhere in the elevator installation, or remotely.

The elevator car 20 is also provided with an optical door sensor 100 attached to the elevator car 10 by sensor mounts 26. The optical door sensor 100 comprises an emitter array 101 for emitting infrared light signals and a receiver array 105 (Figure 2) for detecting the light signals. The sensor mounts 26 are arranged to hold the emitter array 101 and the receiver array 105 in the space between the elevator car 20 and the walls of the elevator shaft 12. In particular, the sensor mounts 26 hold the emitter array 101 and the receiver array 105 opposite each other and aligned so that they can define a light curtain 103 between them, consisting of an array of individual infrared light signals 104 (or light beams), in the space between the elevator car doors 12 and the elevator shaft doors 14 installed at stop positions of the elevator installation 10. The emitter array 101 and the receiver array 105 each comprise a plurality of individual emitters 102 and receivers 106 respectively.

Two cleaning units 40 (one of which is shown in Figure 1) are mounted in the elevator shaft in the upper terminal portion 18 of the elevator shaft, between the upper and middle predetermined stops (i.e. between the upper and middle floors 16). The cleaning units 40 are arranged to clean the emitter array 101 and receiver array 105 respectively in a cleaning operation as the optical door sensor 100, mounted to the elevator car, passes the cleaning units 40. The cleaning units 40 are mounted in the elevator shaft by any suitable means. For example, an attachment portion of a cleaning unit 40 may be mounted to a structural support of the elevator shaft or building, such as a girder, by a number of bolts. The elevator controller includes a cleaning controller for initiating cleaning operations, as described in detail below.

Figure 3 shows a first embodiment of a cleaning unit 41 according to the invention during a cleaning operation in which it cleans the emitter array 101 of the optical door sensor 100. In this embodiment the cleaning unit is a static cleaning unit in that it is not arranged to move relative to the elevator shaft 12.

The cleaning unit 41 comprises an attachment portion 45 by which it is mounted in the elevator shaft 12, a cleaning head 46 and a cleaning element 44 secured to the cleaning head 46. In this embodiment the cleaning element 44 is a brush having a number of bristles arranged to engage the emitter array 101 to clean the emitter array 101.

A corresponding cleaning unit 41 is provided for cleaning the receiver array 105.

In use, the elevator controller controls the motion of the elevator car 20 within the elevator shaft 12. In particular, the elevator controller controls the acceleration of the elevator car 20 from stationary, and the deceleration of the elevator car 20 towards a stop. The elevator controller also limits the maximum speed of the elevator car 20 within the elevator shaft to a passing speed, such as three metres per second.

VThen in a terminal portion 18 of the elevator shaft, the elevator car 20 is always either at rest, accelerating from a stop in a starting phase of motion, or decelerating towards a stop in a stopping phase. Accordingly, the maximum operational speed of the elevator car 20 in a terminal portion 18 is determined by the acceleration and deceleration of the lift away from and towards a stop respectively.

Since the cleaning units 41 are arranged to physically contact the optical door sensor 100, the elevator installation is configured so that the maximum operational speed of the elevator car 20 is less than or equal to a predetermined limit cleaning speed. This prevents the elevator car 20, optical door sensor 100 and cleaning units 41 from being damaged during a cleaning operation due to excessive speed. For example, the limit cleaning speed may be 0.5 to 2 metres per second.

In this embodiment, the extents of the terminal portions 18 are defined so that the maximum operational speed of the elevator car 20 within the terminal portions 18 is less than or equal to the predetermined limit cleaning speed. The extents of the terminal portions therefore depend on the limit cleaning speed and the acceleration and deceleration parameters set in the elevator controller. Consequently, in this embodiment, the elevator controller need not be configured to cap the operational speed of the elevator to a limit cleaning speed during a cleaning operation, provided that the cleaning units 41 are positioned within a terminal portion 18 of the elevator shaft 12. Therefore, the elevator controller need not be updated to apply a cap if the cleaning unit is retrofitted. In other embodiments, the elevator controller may be configured to apply such a cap, irrespective of whether or not the cleaning units are positioned within a terminal portion 18 of the elevator shaft 12.

In use, a cleaning operation will occur each time the optical door sensor 100 passes the cleaning units 41, as the cleaning units 41 are static. Therefore, cleaning operations will occur automatically in the normal use of the elevator.

In addition, the cleaning controller is configured to initiate a cleaning operation by calling the elevator to move past the cleaning unit 41. In particular, as the cleaning unit 41 is located in the upper terminal portion 18 of the elevator shaft, the cleaning controller can call the elevator car 20 to move to the upper terminal stop corresponding to the upper floor 16 of the building.

Further, the cleaning controller is configured to initiate a cleaning operation periodically according to a time-based schedule, for example once a day.

The cleaning controller is also configured to monitor an elevator operating parameter of the elevator installation and initiate a cleaning operation based on the elevator operating parameter. For example, in this embodiment, the cleaning controller monitors the number of elevator car journeys, the number of door closing operations and a cumulative journey time of the elevator car. A cleaning threshold is set for each of these elevator operating parameters, such as 50 elevator car journeys, 100 door closing operations and 1 hour of journey time respectively. The cleaning controller initiates a cleaning operation whenever one of these elevator operating parameters reaches its respective threshold. In this embodiment, the elevator operating parameters may be reset once a cleaning operation is initiated or determined to have taken place, but in other embodiments the elevator operating parameters may be reset independently of each other.

The cleaning unit 41 therefore prevents material from building up on the optical sensor so that it continues to function normally, thereby avoiding the elevator installation being taken out of service. The cleaning unit 41 also reduces the maintenance burden for the elevator installation.

Figure 4 shows a second embodiment of a cleaning unit 42 according to the invention.

In this embodiment, the cleaning unit 42 is a non-contact cleaning unit in that it is arranged to clean the emitter array 101 without making physical contact with the emitter array 101.

The cleaning unit 42 differs from the cleaning unit 41 shown in Figure 3 in that the cleaning element 46 is an air blower having a plurality of blowing nozzles 48 for directing air at the emitter array 101 to clean it. Accordingly, in this embodiment the cleaning unit 42 further comprises a power supply (not shown) for the air blower 46.

In use, the cleaning controller controls the air blower 46 to turn on and off for each cleaning operation. The cleaning controller can be configured to turn the air blower 46 on each time the elevator car 20 passes, or is about to pass, the cleaning unit 42 so that a cleaning operation takes place at every opportunity. The cleaning controller therefore monitors the position of the elevator car 20 as controlled by the elevator controller. Alternatively, the cleaning controller can be configured to turn the air blower 46 on only when a cleaning operation is initiated, i.e. when the elevator car 20 is called to pass the cleaning unit 42, as described above with respect to the first embodiment of the invention.

Figure 5 shows a third embodiment of a cleaning unit 43 according to the invention. In this embodiment, the cleaning unit 43 is deployable from a rest configuration, in which the emitter array 101 of the optical door sensor 100 can pass the cleaning unit 43 without contacting the cleaning unit 43 and being cleaned, to a deployed configuration, in which the emitter array 101 will be cleaned by the cleaning unit 43 in a cleaning operation as it passes the cleaning unit. The cleaning unit 43 is also a contact-based cleaning unit, and so the emitter array 101 will engage with the cleaning element 44 of the cleaning unit 43 during a cleaning operation.

The cleaning unit 43 comprises a support arm 54 for supporting a slidable cleaning rod 56, to which a cleaning head 46 and a cleaning element 48 are mounted. The cleaning rod, cleaning head 46 and cleaning element 48 are slidable between the rest and deployed configurations. Two tension springs 57 couple the cleaning head 46 and the support arm 54 and act to bias the cleaning head 46 to the rest configuration (i.e. towards the support arm 54).

The cleaning unit 43 also comprises a motor 58 for driving a cam 60 arranged to engage with the cleaning rod 56. The support arm 54, motor 58 and cam 60 are mounted in the elevator shaft 12 by an attachment portion 45 of the cleaning unit 43.

The cleaning unit 43 also comprises a motor controller (not shown) for operating the motor 58 and cam 60 so as to move the cleaning unit 43 between the rest configuration and the deployed configuration.

In Figure 5, the cleaning unit 43 is shown in the deployed configuration in which the cleaning rod 56 engages a maximum-radius portion of the cam 60, so that the cleaning rod 56, cleaning head 46 and cleaning element 44 are displaced from the axis of the cam by a maximum amount and the cleaning element 44 is arranged to engage the emitter array 101 in a cleaning operation.

The cleaning unit 43 can be moved to the rest configuration by causing the motor 58 to rotate the cam 60. Rotation of the cam 60 in turn causes the cleaning rod 56 to follow the profile of the cam under the bias of the tension springs 57, so that the cleaning head 46 and cleaning element 44 move away from the emitter array 101 and towards the support arm 54 (i.e. into the rest configuration).

The cleaning controller (not shown) controls the movement of the cleaning unit 43 between the rest and deployed configurations, as will be described in detail below.

In use, the cleaning controller selectively deploys the cleaning unit 43 from the rest configuration to the deployed configuration only when a cleaning operation is initiated.

In this embodiment, a cleaning operation can be initiated either by simply deploying the cleaning unit 43 to the deployed configuration shown in Figure 5 and waiting for the elevator car 20 to pass the cleaning unit 43, or alternatively by both deploying the cleaning unit 43 and calling the elevator car 20 to pass the cleaning unit 43.

The cleaning unit 43 therefore enables control over when a cleaning operation is to occur, which may help to ensure the cleaning unit does not become worn out. Further, in embodiments where the cleaning unit 43 is installed outside of a terminal portion 18 of the elevator shaft (i.e. where the operating speed of the elevator car 20 can be higher than the predetermine limit cleaning speed), the cleaning unit allows the speed of the elevator car to be limited only when the cleaning unit 43 is in the deployed configuration, since there is no need to limit the elevator car speed when the cleaning unit 43 is in the rest configuration.

Figure 6 shows a variation on the cleaning unit 43 shown in Figure 5 in which the emitter array 101 is provided with a ramp 62 at its lower end that is configured to forcibly return the cleaning unit 43 to the rest configuration from the deployed configuration when the elevator car 20 moves upwardly relative to the cleaning unit 43.

In use, the cleaning controller controls the cleaning unit 43 to move to the deployed configuration only when the elevator car 20 is below the cleaning unit 43.

Subsequently, as the elevator car 20 moves upwardly, the cleaning unit 43 engages the emitter array 101 and cleans it in a cleaning operation. Following the cleaning operation, the ramp 62 engages the cleaning head 46 and/or the cleaning element 44 so as to move it back to the rest configuration.

An advantage of this arrangement is that the cleaning unit 43 can be automatically moved back to the rest configuration after a cleaning operation, without the cleaning controller having to determine that the cleaning operation has taken place.

Similarly, in other embodiments, a ramp 62 may be positioned at the upper end of the emitter array 101 (or the receiver array 105), and the cleaning controller may control the cleaning unit 43 to move to the deployed configuration only when the elevator car is above the cleaning unit 43.

Figure 7 shows a further embodiment of a cleaning unit 64. The cleaning unit 64 differs from the cleaning unit 41 shown in Figure 3 and described above only in that the cleaning head 46 is mounted to the attachment portion 45 of the cleaning unit 64 by a resilient arm 66 which in this embodiment comprises a compression spring. The resilient arm 66 is arranged to provide a resilient support for the cleaning head 46 and cleaning element 44 which urges the cleaning element 44 towards the pad of the optical door sensor 100 to be cleaned (in this case the emitter array 101). The resilient arm 66 can accommodate movement of the cleaning element when it engages the optical door sensor 100, so as to reduce the likelihood of either component being damaged during a cleaning operation. The resilient arm 66 also enables the cleaning element to be urged against the optical door sensor 100 under a relatively constant load corresponding to the spring constant of the resilient arm 66 (i.e. of the compression spring).

Elevator installations according to the above described embodiments may be modified to include a test module for conducting a self-diagnostic test on the optical door sensor 100. In such embodiments, the cleaning controller is configured to initiate a cleaning operation based on an output of the test module. In an example embodiment the self-diagnostic test comprises simulating a deterioration of the operating conditions of the optical door sensor 100 by temporarily reducing the light intensity of a light signal from an emitter by a predetermined amount (such as 20%), and determining whether the optical door sensor continues to function normally by determining whether a light signal from an emitter can still be detected by the corresponding receiver. If the light signal cannot be detected, it is determined that an operating margin of the optical door sensor is less than or equal to a margin limit corresponding to the predetermined amount. The cleaning controller is configured to initiate a cleaning operation when the operating margin is determined to be less than the margin limit.

In such embodiments, the elevator controller is configured to initiate a test of the optical door sensor only when the elevator car 20 is in a configuration in which the optical door sensor is not required to detect the presence of an obstacle. For example, the elevator controller can be configured to initiate a test only when the elevator car doors and shaft doors are closed, and the elevator controller may prevent the doors from opening until the test is complete.

It will be appreciated that the term light" means electromagnetic radiation including both visible light and non-visible light such as infrared and ultraviolet light.

Claims

CLAIMS: 1. An elevator installation comprising: an elevator car movable within an elevator shaft, the elevator car having an optical door sensor; and a cleaning unit mounted in the elevator shaft and configured to clean the optical door sensor in a cleaning operation as the optical door sensor passes the cleaning unit.
2. An elevator installation according to claim 1, further comprising an elevator controller configured to control the speed of the elevator car in the elevator shaft.
3. An elevator installation according to claim 2, wherein the elevator controller is configured so that the speed of the elevator car during a cleaning operation is less than or equal to a limit cleaning speed.
4. An elevator installation according to any preceding claim, wherein the cleaning unit is mounted within a terminal portion of the elevator shaft in which the maximum operational speed of the elevator is less than or equal to a limit cleaning speed.
5. An elevator installation according to any preceding claim, wherein the cleaning unit is mounted within a terminal portion of the elevator shaft, so that in use cleaning operations take place exclusively during a starting phase or a stopping phase of the elevator car.
6. An elevator installation according to any preceding claim, wherein the cleaning unit is deployable from a rest configuration to a deployed configuration in which it is arranged to clean the optical door sensor in a cleaning operation as the optical door sensor passes the cleaning unit.
7. An elevator installation according to claim 6, wherein the cleaning unit can be selectively deployed and selectively un-deployed.
8. An elevator installation according to any one of the preceding claims, wherein the optical door sensor comprises an emitter for emitting a light signal and a receiver for detecting the light signal, and wherein the elevator installation comprises a cleaning unit for the emitter and a cleaning unit for the receiver.
9. An elevator installation according to any preceding claim, further comprising a cleaning controller for selectively initiating a cleaning operation.
10. An elevator installation according to claim 9, wherein the cleaning controller is configured to initiate a cleaning operation by deploying the cleaning unit.
11. An elevator installation according to claim 9 or 10, wherein the cleaning controller is configured to initiate a cleaning operation by calling the elevator car to move past the cleaning unit.
12. An elevator installation according to any one of claims 9 to 11, wherein the cleaning controller is configured to periodically initiate a cleaning operation.
13. An elevator installation according to any one of claims 9 to 12, wherein the cleaning controller is configured to monitor at least one elevator operating parameter of the elevator installation and to initiate a cleaning operation based on the at least one elevator operating parameter.
14. An elevator installation according to claim 13, wherein the at least one elevator operating parameter is selected from a group consisting of a service time of the elevator car, a journey time of the elevator car, a count of elevator car stops completed, a count of elevator door opening and/or closing operations completed, a count of elevator car journeys and a distance travelled by the elevator car.
15. An elevator installation according to any one of claims 9 to 14, further comprising a test module configured to test the optical door sensor, wherein the cleaning controller is configured to initiate a cleaning operation based on an output of the test module.
16. An elevator installation substantially as described herein with reference to the drawings.