Patent Description:
It is known to provide an elevator hoistway with a length of tape, arranged to extend vertically in the hoistway, and fixedly fastened to the hoistway wall. The elevator car includes a sensor e.g. a camera, able to sense certain features e.g. incremental markings, along the length of the tape, and the sensed features are used to determine the position of the elevator car within the hoistway. This prior art arrangement is described in greater detail below with reference to <FIG>.

<CIT> discloses a position reference system for use with a conveyance, such as an elevator. The system includes a code affixed to or embedded within a suspension device or primary motion coupling such as a rope or coated steel belt. A reader in a fixed location determines the position of the conveyance.

<CIT> discloses a tension member for an elevator system including one or more tension elements extending along a length of the tension member, and one or more wave guide regions secured to at least one surface of the tension member or integral to the tension member and extending along the length of the tension member. The one or more wave guide regions are configured for transmission of a radio frequency data signal along the one or more wave guide regions.

Certain drawbacks with such known position measurement tape arrangements have been appreciated and the elevator position measurement system according to the present disclosure seeks to address these shortcomings.

According to a first aspect of the invention there is provided an elevator system according to claim <NUM>.

Optionally, the detector unit is positioned at a first end of the elongate tension member.

Optionally, the pulse generator is configured to transmit the pulse along the elongate tension member in a direction towards the detector unit.

Optionally, the pulse generator is mounted on the elevator car and the detector unit is mounted at a fixed position relative to the elongate tension member.

Optionally, the pulse generator is mounted in a fixed position in the hoistway and the detector unit is mounted on the elevator car.

Optionally, the elevator car position measurement system further comprises an initial pulse generator configured to send an initial pulse along the elongate tension member towards the pulse generator to thereby induce a current in the pulse generator.

Optionally, the pulse generator is configured to transmit the pulse along the elongate tension member in a direction towards the detector unit in response to the induced current.

Optionally, the elevator car position measurement system further comprises a terminating connector coupled to the elongate tension member and configured to prevent reflection of the initial pulse back towards the initial pulse generator.

Optionally, the detector unit is configured to record a pulse start time, wherein the pulse start time is a time at which the pulse generator transmits the pulse along the elongate tension member or a time at which the initial pulse generator sends the initial pulse towards the pulse generator.

Optionally, the detector unit further comprises a measurement system control unit configured to determine a time interval between the pulse start time and the time at which the pulse is received by the detector unit.

Optionally, the measurement system control unit is configured to calculate, from the determined time interval, position information indicating the position of the elevator car within the hoistway.

Optionally, the elevator system further comprises an elevator control unit, wherein the measurement system control unit is configured to transmit the position information to the elevator control unit.

Optionally, the elongate tension member comprises a plurality of tension cords surrounded by a sheath, and the pulse generator is configured to send the pulse along one of the plurality of tension cords.

According to a second aspect of the invention there is provided an elevator car position measurement system for an elevator system according to claim <NUM>.

According to a third aspect of invention there is provided a method of measuring a position of an elevator car within a hoistway of an elevator system comprising an elongate tension member operably connected to the elevator car and configured to move the elevator car within the hoistway, the method comprising:.

It will be appreciated that any of the optional features described above in relation to the first aspect of the disclosure may equally be combined with the second or third aspects of the disclosure.

In various examples, the elongate tension member comprises a plurality of cords surrounded by a sheath. At least one of the cords, or a pair of the cords, is electrically conductive and configured to transmit the pulse from the pulse generator along the elongate tension member. This electrically conductive cord, or pair of cords, may comprise a metallic material (such as steel) and/or carbon. One or more of the cords are load-bearing cords. In some examples, the plurality of cords comprises load-bearing cords that are electrically conductive. This means that any of the load-bearing cords can be used to transmit an electrical pulse along the elongate tension member. In some other examples, the plurality of cords comprises load-bearing cords that are not electrically conductive (such as polymeric cords) and at least one electrically conductive component that is configured to transmit an electrical pulse along the elongate tension member in parallel with the load-bearing cords. This means there is an electrically conductive component that is dedicated to pulse transmission, which can be independent of the tension member's load-bearing capability.

In some examples, the elongate tension member comprises a plurality of steels cords surrounded by a polymeric sheath, e.g. a coated steel belt.

The examples described herein advantageously provide an elevator car position measurement system that does not require installation of position measurement tape along the complete height of the hoistway, and that utilises the elongate tension member already present in the system. This can reduce material cost and installation time as well as providing space gain in the hoistway due to missing position measurement tape.

Furthermore, measurement of the position of the elevator car using the examples described herein is independent from temperature or expansion or contraction in the building structure, so can offer improved reliability compared to known systems.

Some examples of this disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which:.

<FIG> shows a perspective view of an elevator system <NUM> as is known in the art. An elevator car <NUM> is arranged to move vertically within the hoistway <NUM>, guided along guide rails <NUM>. The hoistway <NUM> includes a position measurement tape <NUM>. The position measurement tape <NUM> is fixed to a hoistway wall by an upper fixing device <NUM>, connected to the upper end of the position measurement tape <NUM>, and a lower fixing device <NUM>, connected to the lower end of the position measurement tape <NUM>.

The elevator car <NUM> moves vertically within the hoistway <NUM>, along the guide rails <NUM>, driven by any suitable drive system as is known in the art, and controlled by an elevator system controller (not shown). A sensor <NUM> is mounted to the elevator car <NUM>, in a position which is aligned with the position measurement tape <NUM>.

The sensor <NUM> senses position markings e.g. increments, on the position measurement tape <NUM> e.g. using a camera. The sensor <NUM> can either process the collected data itself or pass the data to another component of the elevator system e.g. the elevator system controller, for further processing. This data is processed to determine a position i.e. height, within the hoistway <NUM>. For example, each position marking could be unique and could be looked up in a lookup table (created in an initial calibration process) which includes the corresponding height for each position marking. In this way the position measurement tape <NUM> is usable by the elevator system <NUM> to determine the vertical position of the elevator car <NUM> for any given position within the hoistway <NUM>.

However, such a position reference system requires the position measurement tape <NUM> to extend along the complete height of the hoistway <NUM> in order to determine the vertical position of the elevator car <NUM> at any given height. This can bring additional cost for the tape material, additional installation costs, and requires space in the hoistway.

An elevator system according to the present disclosure, as described herein below with reference to <FIG>, seeks to address these shortcomings of the prior art elevator system <NUM>.

<FIG> shows a side view of an elevator system <NUM> according to a first example of the present disclosure. The elevator system <NUM> includes an elevator car <NUM> and an elongate tension member <NUM> operably coupled to the elevator car <NUM> and configured to move the elevator car <NUM> within a hoistway <NUM>.

In this example, the elevator car <NUM> is suspended by the elongate tension member <NUM> in a <NUM>:<NUM> roping configuration as is known in the art. In this configuration, the elongate tension member <NUM> is configured to move through a traction sheave <NUM> powered by an elevator drive unit <NUM> such that the elevator car <NUM> moves up and down within the hoistway <NUM>. A counterweight <NUM> is suspended from the elongate tension member <NUM> on an opposite side of the traction sheave <NUM> to the elevator car <NUM>. Both the elevator car <NUM> and the counterweight <NUM> are suspended by the elongate tension member <NUM> via at least one pulley. The elongate tension member <NUM> is fixed at each end with respect to the hoistway with an end terminal <NUM> at the elevator car <NUM> side of the elongate tension member <NUM> and a further end terminal <NUM> at the counterweight <NUM> side of the elongate tension member <NUM>.

The elongate tension member <NUM> may be any belt, cable or rope suitable for passing through the traction sheave <NUM> and for supporting the weight of the elevator car <NUM> and the counterweight <NUM>. In this example, the elongate tension member <NUM> is a coated steel belt.

Referring also to <FIG> and <FIG>, the elevator system <NUM> includes a position measurement system <NUM> including a pulse generator <NUM>. The pulse generator <NUM> is configured to transmit a pulse <NUM> along the elongate tension member <NUM>. In other words, the pulse generator <NUM> is configured to send a pulse <NUM> along at least one component of the elongate tension member <NUM>.

Aptly, the pulse generator <NUM> is configured to transmit an electrical pulse <NUM> along the elongate tension member <NUM>, and in particular along an electrically conductive component of the elongate tension member <NUM>. For example, the pulse generator <NUM> is configured to induce an electrical pulse <NUM> along the elongate tension member <NUM> by electromagnetic induction.

The position measurement system <NUM> further includes a detector unit <NUM>. The detector unit <NUM> is configured to receive the pulse <NUM> from the pulse generator <NUM> and record a time at which the pulse <NUM> is received. The detector unit <NUM> includes a monitoring connection <NUM> configured to electrically couple the detector unit <NUM> to the elongate tension member <NUM>.

The pulse generator <NUM> and the detector unit <NUM> are arranged such that a length of the elongate tension member <NUM> along which the pulse <NUM> is transmitted changes dependent on a position of the elevator car <NUM> in the hoistway <NUM>.

In this example, the pulse generator <NUM> is mounted on the elevator car <NUM> and the detector unit <NUM> is mounted at a fixed position relative to the elongate tension member <NUM>. In this example the detector unit <NUM> is mounted at the end terminal <NUM> of the elongate tension member <NUM> closest to the elevator car <NUM>. As such, as the elevator car <NUM> moves vertically up and down within the hoistway <NUM>, the length of the portion of elongate tension member <NUM> between the pulse generator <NUM> and the detector unit <NUM> changes according to the position of the elevator car <NUM>. The length of the elongate tension member <NUM> through which the pulse <NUM> travels from the pulse generator <NUM> to the detector unit <NUM> therefore changes according to the position of the elevator car <NUM> within the hoistway <NUM>.

The position measurement system <NUM> is configured to determine the length of the elongate tension member <NUM> along which the pulse <NUM> is transmitted based on the time the detector unit <NUM> receives the pulse <NUM>. The position of the elevator car <NUM> can then be determined according to the determined length of elongate tension member <NUM> along which the pulse <NUM> is transmitted between the pulse generator <NUM> and the detector unit <NUM>.

<FIG> and <FIG> illustrate the operation of the position measurement system <NUM> of <FIG> in further detail. The position measurement system <NUM> further includes an initial pulse generator <NUM>, which in this example is located at the detector unit <NUM>. In this example, the position measurement system <NUM> includes a position measurement control unit <NUM>, which includes the initial pulse generator <NUM>.

The initial pulse generator <NUM> is configured to send an initial pulse <NUM> along the elongate tension member <NUM> towards the pulse generator <NUM>, which in this example is positioned on the elevator car <NUM>. The initial pulse <NUM> induces a current in the pulse generator <NUM>. In response to the induced current, the pulse generator <NUM> is configured to transmit a pulse <NUM> back towards the detector unit <NUM> as shown in <FIG>. In some examples, there may be a time delay between the initial pulse <NUM> inducing the current in the pulse generator <NUM> and the pulse generator <NUM> transmitting the pulse <NUM> back to the detector unit <NUM>. In this example the pulse generator <NUM> is an inductive pulse transceiver.

The detector unit <NUM> may include a pulse detector <NUM> configured to detect the pulse <NUM> and a measurement system control unit <NUM> configured to record the time at which the pulse <NUM> is received.

In addition to recording the time at which the pulse <NUM> is received by the detector unit <NUM>, the detector unit <NUM> is further configured to record a pulse start time. A time interval between the pulse start time and the time at which the pulse <NUM> is received by the detector unit <NUM> may then be used to calculate the length of elongate tension member <NUM> along which the pulse <NUM> has travelled, i.e. the length of elongate tension member <NUM> between the pulse generator <NUM> and the detector unit <NUM>.

In this example the pulse start time is the time at which the initial pulse generator <NUM> sends the initial pulse <NUM> towards the pulse generator <NUM>. In other examples, the pulse start time may be the time at which the pulse generator <NUM> transmits the pulse <NUM> along the elongate tension member towards the detector unit <NUM>.

The measurement system control unit <NUM> is further configured to determine a time interval between the pulse start time and the time at which the pulse <NUM> is received by the detector unit <NUM>.

In this example the detector unit <NUM> includes the measurement system control unit <NUM>. In some examples, the measurement system control unit <NUM> may include a time-to-digital converter 336a configured to record the pulse start time and the time at which the pulse <NUM> is received by the pulse detector <NUM>. The time-to-digital converter 336a is discussed in more detail below with reference to <FIG>. The time-to-digital converter 336a may include the initial pulse generator <NUM> and the pulse detector <NUM>. In this way, the pulse detection and the pulse generation may be an integral function of the time-to-digital converter 336a such that pulse generation and pulse detection may both be performed by the time-to-digital converter 336a.

The measurement system control unit <NUM> is further configured to calculate, from the determined time interval, position information indicating the position of the elevator car <NUM> within the hoistway <NUM>. To calculate the position information, the measurement system control unit <NUM> may first determine the length of the elongate tension member <NUM> along which the pulse <NUM> is transmitted based on the determined time interval. The determined length of the elongate tension member <NUM> along which the pulse <NUM> is transmitted may then be used to determine the position of the elevator car <NUM>, for example using a predetermined algorithm or a look up table. The predetermined algorithm or look-up table may be determined using a calibration process as described in more detail below with reference to <FIG>.

As described above, in this example the elongate tension member <NUM> is a coated steel belt. The coated steel belt includes at least one pair of tension cords 338a, 338b. The elongate tension member <NUM> may further include a plurality of tension cords configured for load-bearing. The tension cords 338a, 338b are aptly electrically conductive such that they can transmit an electrical pulse. For example, the tension cords 338a, 338b may be steel cables. The tension cords 338a, 338b are surrounded by a sheath <NUM>.

As shown in <FIG> and <FIG>, the monitoring connection <NUM> is configured to couple to each of the tension cords 338a, 338b. The first tension cord 338a is coupled to the initial pulse generator <NUM> and the measurement system control unit <NUM> including the pulse detector <NUM>. The second tension cord 338b is coupled to a terminating connector <NUM>. The tension cords 338a, 338b, are electrically coupled via a shortening connection <NUM> at or near the end terminal <NUM> adjacent the counterweight <NUM>. The initial pulse generator <NUM> and the pulse generator <NUM> are configured to send the initial pulse <NUM> and the pulse <NUM> along a first tension cord 338a of the pair of tension cords 338a, 338b.

To help prevent reflection of the initial pulse <NUM> back towards the initial pulse generator <NUM>, the terminating connector <NUM> is coupled to the second tension cord 338b and is configured to have an impedance substantially equal to the characteristic impedance of the elongate tension member <NUM>.

The initial pulse generator <NUM> and the pulse generator <NUM> may be configured to generate any pulse that is suitable for travelling along the tension cords 338a, 338b. In this example, the initial pulse generator <NUM> and the pulse generator <NUM> are configured to generate a voltage pulse with a square waveform, but it will be appreciated that other waveforms would also be suitable, for example a sinusoidal, triangular or saw tooth waveform may also be suitable.

Referring back to <FIG>, the elevator system <NUM> may further include a secondary elevator car position reference system. The secondary elevator car position reference system includes position measurement tape 224a-c located at each door zone 222a-c in the hoistway <NUM>. A sensor <NUM> is mounted to the elevator car <NUM>, in a position which aligns with the position measurement tape 224a-c. The sensor <NUM> senses position markings e.g. increments, on the position measurement tape 224a-c, e.g. using a camera.

The sensor <NUM> can either process the collected data itself or pass the data to another component of the elevator system e.g. an elevator system control unit, for further processing.

The secondary elevator car position reference system can be utilized in combination with the position measurement system <NUM> to provide high resolution position measurements of the elevator car <NUM> at each door zone 222a-c within the hoistway. The position measurement system <NUM> of the present disclosure enables position measurement of the elevator car through the full height of the hoistway <NUM> without the need for the higher resolution position measurement tape 224a-c to be positioned along the full height of the hoistway <NUM>. Thus, shorter lengths of position measurement tape 224a-c may be utilised, thereby reducing material and installation costs. Furthermore, the space required in the hoistway <NUM> is reduced since the position measurement tape 224a-c is only provided at the door zones 222a-c.

<FIG> shows a side view of an elevator system <NUM> according to a second example of the present disclosure. The elevator system <NUM> includes an elevator car <NUM> and an elongate tension member <NUM> operably coupled to the elevator car <NUM> and configured to move the elevator car <NUM> within a hoistway <NUM>.

In this example, the elevator car <NUM> is suspended from a first end of the elongate tension member <NUM> in a <NUM>:<NUM> roping configuration as is known in the art. In this configuration, the elongate tension member <NUM> is configured to move through a traction sheave <NUM> powered by an elevator drive unit <NUM> such that the elevator car <NUM> moves up and down within the hoistway <NUM>. A counterweight <NUM> is suspended from a second end of the elongate tension member <NUM> and on an opposite side of the traction sheave <NUM> to the elevator car <NUM>.

The elevator system <NUM> includes many of the same components as the elevator system <NUM> described above in relation to <FIG> and <FIG>, which will not be described again in detail.

However, in this example the pulse generator <NUM> is mounted at a fixed position in the hoistway <NUM> rather than at the elevator car <NUM>. In this example, the pulse generator <NUM> is mounted at the traction sheave <NUM>. The detector unit <NUM> is mounted on the elevator car <NUM> such that it is in a fixed position relative to the end terminal <NUM> of the elongate tension member <NUM>. In this example, the detector unit <NUM> is positioned at the first end of the elongate tension member <NUM>, which in this case is at the elevator car <NUM>. In this way, as the elevator car <NUM> moves vertically up and down within the hoistway <NUM>, the length of the portion of elongate tension member <NUM> between the pulse generator <NUM> and the detector unit <NUM> changes according to the position of the elevator car <NUM>. The length of the elongate tension member <NUM> through which the pulse travels from the pulse generator <NUM> to the detector unit <NUM> therefore changes according to the position of the elevator car <NUM> within the hoistway <NUM>.

<FIG> and <FIG> illustrate the operation of the position measurement system <NUM> of <FIG> in further detail. It will be appreciated that the operation of the system of <FIG> and <FIG> is substantially identical to that described with reference to <FIG> and <FIG>, except for the positioning of the detector unit <NUM> and the pulse generator <NUM> within the elevator system <NUM> as described above with reference to <FIG>.

<FIG> illustrates communication between components of the position measurement system and the elevator system. The position measurement system is substantially the same as in the examples described above, and includes a pulse generator <NUM> and a detector unit <NUM> including a measurement system control unit <NUM>. In this example, the measurement system control unit <NUM> includes a time-to-digital converter 336a and a microcontroller 336b.

The elevator system further includes a wear detection device <NUM>. The wear detection device <NUM> may be configured to monitor the physical condition of the elongate tension member <NUM>. For example, the wear detection device <NUM> may be configured to monitor the condition of the elongate tension member <NUM> by monitoring the electrical resistance of one or more tension cords 338a, 338b of the elongate tension member <NUM>.

The elevator system further includes an elevator control unit <NUM>. The elevator control unit <NUM> is configured to communicate with the detector unit <NUM> and the wear detection device <NUM>. For example, the elevator control unit <NUM> may be configured to transmit position measurement and/or a calibration command and parameters to the detector unit <NUM>. The elevator control unit <NUM> may also be configured to read position information from the detector unit <NUM>. The elevator control unit <NUM> may be further configured to communicate with the wear detection device <NUM> and read wear status of the elongate tension member <NUM> from the wear detection device <NUM>.

The pulse generator <NUM> may be an inductive pulse transceiver and operates as described above in relation to <FIG>. The pulse generator <NUM> is configured to receive a pulse <NUM> from the detector unit <NUM> and, in response, send a pulse <NUM> to the detector unit <NUM> along the elongate tension member <NUM>.

In this example, the measurement system control unit <NUM> includes the time-to-digital converter 336a and the microcontroller 336b. The time-to-digital converter 336a is configured to send the pulse <NUM> pulse to the pulse generator <NUM>. For example, the time-to-digital converter 336a may include an initial pulse generator configured to send the pulse <NUM> to the pulse generator <NUM>. The time-to-digital converter 336a is also configured to receive the pulse <NUM> from the pulse generator <NUM>. For example, the time-to-digital converter 336a may include a pulse detector to detect the pulse <NUM> from the pulse generator <NUM>. The time-to-digital converter 336a may further be configured to record a first timestamp relating to the time at which the time-to-digital converter 336a sends the initial pulse <NUM> to the pulse generator <NUM> and a second timestamp relating to the time at which the time-to-digital converter 336a receives the pulse <NUM> from the pulse generator <NUM>. The first and second timestamps may be stored in a memory in the time-to-digital converter 336a.

The microcontroller 336b may be configured to manage the time-to-digital converter 336a. This may include reading the first and second timestamps from the time-to-digital converter 336a and converting the timestamps into position information relating to the position of the elevator car <NUM> in the hoistway <NUM>. The microcontroller 336b may be configured to transmit the position information to the elevator control unit <NUM>. The microcontroller may be further configured to store calibration reference information, as will be described further below with reference to <FIG>.

In this example the wear detection device <NUM> is provided separately to the detector unit <NUM>. However, it will be appreciated that in some examples the wear detection device <NUM> may be provided integrally together with the detector unit <NUM>. In this configuration both the wear detection device <NUM> and the position measurement system may advantageously couple to the pair of tension cords 338a, 338b of the elongate tension member <NUM> at the same location. As such, it is possible that the position measurement system of the present disclosure may be retrofitted to an existing elevator system, which includes a wear detection device <NUM>.

For example, when retrofitting to an existing installation, the detector unit <NUM> may be provided separately to the wear detection device <NUM>. In this case, the detector unit <NUM> and the wear detection device <NUM> may each couple to the elongate tension member <NUM> via the same monitoring connection <NUM>.

The wear detection device <NUM> typically includes a microprocessor communicating with the elevator control unit <NUM>. As such, the position measurement system may optionally share the same microprocessor and communication components with the wear detection device <NUM>. In other words, the detector unit <NUM> may be integrated with the wear detection device <NUM> and both the detector unit <NUM> and the wear detection device may couple to the elongate tension member <NUM> via the same monitoring connection <NUM>. This configuration may be advantageous for new installations to help reduce component parts, and reduce installation time and cost.

<FIG> illustrates a method <NUM> of measuring a position of an elevator car <NUM> within a hoistway <NUM> of an elevator system including an elongate tension member <NUM> operably connected to the elevator car <NUM> and configured to move the elevator car <NUM> within the hoistway <NUM>.

At a first step <NUM> the method includes transmitting a pulse <NUM> from a first location on an elongate tension member <NUM> towards a detector at a second location on the elongate tension member <NUM>. The first location and the second location may be any suitable location in the hoistway <NUM>, so long as they are positioned such that a length of the elongate tension member <NUM> between the first location and the second location changes dependent on a position of the elevator car <NUM> in the hoistway <NUM>.

For example, as described above in an elevator system configured with a <NUM>:<NUM> roping configuration, the first location may be on the elevator car <NUM>, and the second location may be at an end terminal <NUM> of the elongate tension member <NUM> closest to the elevator car <NUM>. In an elevator system configured with a <NUM>:<NUM> roping configuration, the first location may be at a fixed position in the hoistway <NUM>, for example at the traction sheave <NUM>, and the second location may be on the elevator car <NUM>.

A first method step <NUM> may include recording a pulse start time. As described above, the pulse start time may be the time at which an initial pulse generator <NUM> sends the initial pulse <NUM> towards the pulse generator <NUM> at the first location. In other examples, the pulse start time may be the time at which the pulse generator <NUM> at the first location transmits the pulse <NUM> along the elongate tension member <NUM> towards the detector unit <NUM> at the second location.

A second method step <NUM> includes recording a time at which the pulse is received at the second location. This may include recording the time at which the pulse <NUM> is received by the detector unit <NUM> at the second location.

At step <NUM> the method <NUM> includes calculating, based on the recorded time, the length of the elongate tension member <NUM> along which the pulse is transmitted. The length of the elongate tension member <NUM> along which the pulse is transmitted may correspond to the length of elongate tension member between the first and second location. To calculate the length of tension member between the first and second location the method may include calculating a time interval between a pulse start time and the time at which the pulse <NUM> is received by the detector unit <NUM> at the second location. It will be appreciated that the time interval increases as the length of the elongate tension member <NUM> along which the pulse is transmitted increases. In practice, a time delay is present between the time at which the initial pulse <NUM> arrives at the pulse generator <NUM> and the time at which the pulse generator <NUM> sends the pulse <NUM> back to the detector <NUM>. As such, a time value equal to the time interval minus the time delay is proportional to the length of the elongate tension member <NUM> along which the pulse is transmitted.

At step <NUM> the method <NUM> includes determining, based on the calculated length, a position of the elevator car <NUM> in the hoistway <NUM> of the elevator system. This step may include referring to calibration information to determine the absolute position of the elevator car <NUM> in the hoistway <NUM>. For example, the calibration information may include an algorithm or look-up table to convert the calculated length to position information indicating the position of the elevator car <NUM> in the hoistway <NUM>. As described above, the position information may be communicated to an elevator control unit <NUM>.

<FIG> illustrates an example calibration process <NUM> for calibrating the position measurement system of the present disclosure. The calibration process <NUM> may be initially carried out at installation. In addition, the calibration process <NUM> may be repeated throughout the lifetime of the elevator system <NUM>, <NUM> in response to changes in the properties of the elongate tension member <NUM> due to natural wear, for example.

At step <NUM> the status of the elongate tension member <NUM> is checked. The status may be checked using a wear detection device <NUM>. The wear status of the elongate tension member <NUM> may be communicated to and read by the elevator control unit <NUM>.

At step <NUM> the elevator control unit <NUM> may determine whether calibration of the position measurement system is necessary. For example, if the elevator control unit <NUM> determines that the wear status of the elongate tension member has changed by at least a predetermined amount since the last calibration, the elevator control unit <NUM> will determine that calibration is necessary.

At step <NUM> the calibration process <NUM> includes positioning the elevator car <NUM> in a specific position in the hoistway <NUM>. For example, the elevator car <NUM> may be positioned in the region of a door zone 222a-c, with the absolute position being measured by a secondary position reference system including position measurement tape 224a-c as described above with reference to <FIG>.

At step <NUM> the elevator control unit <NUM> may transmit a calibration command to the position measurement system control unit <NUM>.

At step <NUM> the position measurement control unit <NUM> may communicate with the pulse generator <NUM> to send a pulse to the detector unit <NUM>. The position measurement control unit may record the pulse start time and the time at which the pulse <NUM> is received by the detector unit <NUM>.

At step <NUM> the position measurement control unit <NUM> may store the time interval between the pulse start time and the time at which the pulse is received by the detector unit as reference for the subsequent position measurements.

Steps <NUM> to <NUM> may be repeated as necessary to store multiple reference points. The position measurement control unit <NUM> may determine an algorithm or generate a lookup table based on the reference points to convert time interval information to elevator car position information.

At step <NUM> the position measurement control unit <NUM> may transmit information indicating completion of calibration process to the elevator controller <NUM>.

It will be appreciated that various modifications may be made to the examples described herein. For example, although the position measurement system is described above in the context of an elevator system with a <NUM>:<NUM> roping or <NUM>:<NUM> roping configuration, it will be appreciated that the position measurement system may also be employed in an elevator system with a different roping configuration by appropriately positioning the pulse generator and the detector unit such that the length of the elongate tension member in between changes according to the position of the elevator car in the hoistway.

It will also be appreciated that in some examples the initial pulse generator described in the examples above may be omitted and the pulse generator may transmit the pulse directly to the detector unit without the need for the initial pulse. For example, a voltage may be applied directly to the pulse generator to generate and transmit a pulse along the elongate tension member towards the detector unit. In this instance, the pulse start time would be recorded as the time at which the pulse generator sends the pulse towards the detector unit.

Although the pulse generator and the detector unit are shown in specific positions in the examples described above, in other examples the pulse generator and the detector unit may be provided at different positions. These different positions may be any position in which one of the pulse generator and the detector moves dependent on the position of the elevator car within the hoistway such that the length of the elongate tension member along which the pulse is transmitted from the pulse generator to the detector unit changes dependent on the position of the elevator car within the hoistway.

For example, one of the pulse generator and detector unit may be located on either the elevator car or the counterweight, or at a location on the elongate tension member near the elevator car or the counterweight such that they move dependent on movement of the elevator car. The other of the pulse generator and the detector unit may be located at a fixed position within the hoistway such that the length of elongate tension member between the pulse generator and the detector unit changes dependent on the position of the elevator car within the hoistway.

The elongate tension member <NUM> described herein may aptly be an elongate suspension member configured for suspending the elevator car within the hoistway. The suspension member is configured for supporting the weight of the elevator car and counterweight within the hoistway. For example, the elongate tension member may be any suitable suspension member including a suspension belt, rope, or cable.

The elongate tension member <NUM> in any of the examples described herein may include at least one electrically conductive component. The pulse generator <NUM> may be configured to transmit the pulse, which may be an electrical pulse, along the electrically conductive component. Similarly, the initial pulse generator <NUM> may be configured to transmit the initial pulse, which may be an electrical pulse, along the electrically conductive component.

The electrically conductive component may aptly be the tension cords 338a, 338b in the examples described above. That is the tension cords 338a, 338b are aptly electrically conductive.

In other examples the elongate tension member <NUM> may include an electrically conductive component provided specifically for transmitting the pulse along the elongate tension member <NUM>. For example, an electrically conductive wire may be embedded within a belt or rope forming the elongate tension member <NUM>.

Claim 1:
An elevator car position measurement system (<NUM>, <NUM>) for an elevator system (<NUM>, <NUM>) comprising an elongate tension member (<NUM>) operably connected to an elevator car (<NUM>) and configured to move the elevator car (<NUM>) within the hoistway (<NUM>), the elevator car position measurement system (<NUM>, <NUM>) comprising:
a pulse generator (<NUM>) configured for transmitting a pulse (<NUM>) along the elongate tension member (<NUM>);
a detector unit (<NUM>) configured to receive the pulse (<NUM>) from the pulse generator (<NUM>) after the pulse (<NUM>) has been transmitted along a length of the elongate tension member (<NUM>) and to record a time at which the pulse (<NUM>) is received;
wherein one of the pulse generator (<NUM>) and the detector unit (<NUM>) is configured to be arranged to move within the hoistway (<NUM>) dependent on a position of the elevator car (<NUM>) within the hoistway (<NUM>) such that, in use, a length of the elongate tension member (<NUM>) along which the pulse (<NUM>) is transmitted changes dependent on a position of the elevator car (<NUM>) within the hoistway (<NUM>), and
wherein the elevator car position measurement system (<NUM>, <NUM>) is configured to calculate the length of the elongate tension member (<NUM>) along which the pulse (<NUM>) is transmitted based on the recorded time, and determine the position of the elevator car (<NUM>) within the hoistway (<NUM>) based on the determined length.