ARRANGEMENT AND METHOD FOR DETERMINING THE POSITION OF AN
ELEVATOR CAR
The invention relates to an arrangement and a method for determining the
position of an elevator car.
The position of the elevator car in the elevator hoistway is conventionally
determined with a magnetic switch fixed to the elevator car. In this case
permanent magnets are disposed in the elevator system on the floor levels as
well as at the end zone of the elevator hoistway, among other places. According
to the base principle of position determination, the mechanical contact of the
magneoc switch fixed to the elevator car changes its state when the magnetic
switch is scan into the proximity of a permanent magnet fitted in the elevator
hoistway.
The mechanical contact of the magnetic switch does not express the explicit
position of the elevator car. For this reason the elevator car must drive to a known
reference point in the elevator hoistway after losing the position information. This
type of searching for the position of the elevator car must be performed e.g. after
an electricity outage.
The mechanical contacts of magnetic switches are unreliable; vibration or an
impact may cause failure of the contact, and mechanical contacts also oxidize
easily.
The purpose of the invention is to solve the aforementioned problems as well as
the problems disclosed in the description of the invention below. Therefore the
invention presents a determination of the position of the elevator car that is
more reliable and simpler than prior art.
The arrangement according to the invention for determining the position of an
elevator car in the elevator hoistway is characterized by what is disclosed in the
characterization part of claim 1. The method according to the invention for
determining the position of an elevator car in the elevator hoistway is
characterized by what is disclosed in the characterization part of claim 6. The
measuring apparatus according to the invention for determining the position of a
moving object is characterized by what is disclosed in the characterization part
of claim 10. The position identifier according to the invention for determining the
position of a moving object is characterized by what is disclosed in the
characterization part of claim 11. Other embodiments of the invention are
characterized by what is disclosed in the other claims. Some inventive
embodiments are also discussed in the descriptive section of the present
application. The inventive content of the application can also be defined
differently than in the claims presented below. The inventive content may also
consist of several separate inventions, especially if the invention is considered
in the ight of expressions or implicit sub-tasks or from the point of view of
advantages or categories of advantages achieved. In this case, some of the
attributes contained in the claims below may be superfluous from the point of
view of separate inventive concepts.
The arrangement according to the invention for determining the position of an
elevator car in the elevator hoistway comprises: a measuring apparatus fitted in
connection with the elevator car, which measuring apparatus is arranged to
form an electromagnetic radio-frequency measuring signal, for determining the
position of the elevator car; and also a position identifier fitted in a selected
location in relation to the elevator hoistway, which position identifier is arranged
to connect inductively to the aforementioned electromagnetic measuring signal,
and also after connecting to send a determined pulse pattern to the measuring
apparatus via the aforementioned measuring signal.
In the method according to the invention for determining the position of an
elevator car in the elevator hoistway: a measuring apparatus that moves along
with the elevator car is fitted in connection with the elevator can the measuring
apparatus is arranged to form an electromagnetic radio-frequency measuring
signal, for determining the position of the elevator car; a position identifier is
fitted in a selected location in relation to the elevator hoistway; the position
identifier is arranged to connect inductively to the aforementioned
electromagnetic measuring signal; and also after connecting to send a
determined pulse pattern to the measuring apparatus via the aforementioned
measuring signal.
The measuring apparatus for determining the position of a moving object
according to the invention comprises: an apparatus frame, comprising a
mechanical fixing interface to the moving object; an output for the position
information of the moving object; a circuit board fixed to the apparatus frame, as
well as fated to the circuit board: a loop antenna formed on the circuit board; a
transmitter connected to the antenna; and also a controller connected to the
transmitter. The circuit board is fitted to be connected to the moving object via
the apparatus frame such that the surface of the circuit board is essentially in
the direction of movement, and the loop antenna of the circuit board is arranged
to form an electromagnetic radio-frequency measuring signal in essentially the
perpendicular drection to the movement of the object, for determining the
position of the moving object.
The position identifier according to the invention for determining the position of
a moving object comprises an RFID unit and also a fixing interface for fixing the
position identifier in relation to the path of movement of the object The position
identifier is fitted to be fixed for aligning the antenna of the RFID unit such that
the antenna connects inductively to the radio-frequency measuring signal
formed in an essentially perpendicular direction to the movement of the object.
With the invention at least one of the following advantages, among others, is
achieved:
Since the position identifier is passive, no separate electricity supply for the
position identifier is needed. In this case the position identifier is easy to fit into
the arrangement according to the invention.
The position identifier is fitted to determine the explicit position of the elevator
car. In this case, e.g. after an electricity outage the position information of the
elevator car can be returned by driving the elevator car into connection with the
nearest position identifier, in which case searching for the position of the
elevator car according to prior art does not need to be performed.
By means of the checksum of the position identifier, the reliability of the
determination of the identification of the position identifier can be improved.
When the position identifier comprises at least two RFID units, the
identifications of these can be compared to each other, in which case the
condition of the position identifier can be monitored.
The position information of the elevator car can be determined linearly by
measuring the magnetic field produced by a permanently-magnetized marking
piece. The position information can in this case also be determined with two
channels, from the RFID unit and from the permanently-magnetized marking
piece, by means of the measuring apparatus according to the invention.
Presentation of drawings
In the following, the invention will be described in more detail by the aid of a few
examples of its embodiments with reference to the attached drawings, wherein
Fig. 1 presents an elevator system into, which an arrangement according
to the invention is fitted
Fig. 2 presents the structure of a pulse pattern according to the invention
Fig. 3 presents an inductive connection of a measuring apparatus and a
position identifier
Fig. 4 presents an arrangement according to the invention for determining
the position of the floor level of the elevator
Fig. 5 presents an arrangement according to the invention for determining
the terminal floor and also the end limits of the elevator hoistway
Rg. 6 presents one arrangement according to the invention for
determining the linear position of the elevator car
Fig. 7 presents a second arrangement according to the invention for
determining the linear position of the elevator car
Fig. 8 presents a structure of the measuring apparatus according to the
invention
Embodiments
Fig. 1 presents an elevator system, in which the elevator car 1 is moved in the
elevator hoistway 2 in a manner that is, in itself, prior art. The elevator motor 27
moves the elevator car 1 in the elevator hoistway 2 essentially in the vertical
direction between floor levels 25 via the elevator ropes (not shown in the figure).
A frequency converter 26 regulates the movement of the elevator motor 27 by
adjusting the power supply between the electricity network 28 and the elevator
motor. Adjustment of the movement of the elevator car and also regulation of
the elevator traffic occurs with the elevator controller 29, as a response to calls
sent from the floor levels 25 as well as to car calls sent from the elevator car
and transmitted by the controller 30 of the elevator car.
One arrangement according to the invention for determining the position of the
elevator car 1 in the elevator hoistway 2 is fitted to the elevator system
according to Fig. 1. A measuring apparatus 3 is fixed in connection with the roof
of the elevator car 1 with fixing means 31. The measuring apparatus 3
comprises a loop antenna, which is aligned such that the direction of the
electromagnetic radio-frequency measuring signal 5 of the antenna is
essentially at right angles with respect to the direction of movement of the
elevator car. Position identifiers 4 are fitted in selected locations in relation to
the elevator hoistway 2. The position identifiers 4 are e.g. fixed to the guide rail
(not in figure) of the elevator car in connection with the floor levels 25 with a
magnetic fixing. In the situation of Fig. 1, the floor of the elevator car 1 is
situated at the floor level 25, in which case the measuring apparatus 3 and the
position identifier 4 corresponding to the floor level are situated opposite each
other as shown in the figure. In this case, when the position identifier 4 of the
floor level is situated in the immediate proximity of the electromagnetic
measuring signal 5 formed by the measuring apparatus 3, the position identifier
4 connects inductively to the aforementioned electromagnetic measuring signal
5. After connecting, the position identifier sends a determined pulse pattern 6 to
the measuring apparatus 3 via the aforementioned measuring signal 5. The
measuring apparatus 3 individualizes the position identifier 4 in question on the
basis of the pulse pattern 6. The position thus determined is conveyed from the
measuring apparatus 3 first to the controller 30 of the elevator car, and onwards
from the controller of the elevator car to the elevator controller 29, along the
traveling cable or e.g. a wireless data transfer channel. Fig. 3 presents the
connecting mechanism between the measuring apparatus 3 and the position
identifier 4. Fig. 2 presents the pulse pattern 6 formed by the position identifier.
In Fig. 3 the measuring apparatus 3 is disposed in the immediate proximity of
the position identifier 4. A high-frequency excitation signal 34 is supplied with
the transmitter 20 to the loop antenna 19 of the measuring apparatus 3. The
loop antenna forms an electromagnetic radio-frequency measuring signal 5 in
response to the excitation signal. When the antenna of the position identifier 4 is
situated at an essentially shorter distance from the loop antenna of the
measuring apparatus 3 than the wavelength of the measuring signal 5, the
antenna of the position identifier 4 inductively connects to the aforementioned
measuring signal 5. In one embodiment of the invention the frequency of the
electromagnetic measuring signal 5 is 13.56 MHz. The distance between the
loop antenna 19 of the measuring apparatus and the antenna of the position
identifier 4 is in this case at most approx. 30 mm.
The position identifier 4 comprises a microcircuit 32, which receives its
operating electricity from the measuring signal 5 during the inductive
connection. In this case the measuring signal 5 produces a response signal in
the antenna of the position identifier, which response signal is rectified into the
operating electricity of the microcircuit 32 with a rectifying bridge. The
microcircuit changes the loading of the excitation signal 34 via the inductively
connected measuring signal 5. The change in the loading occurs by controlling
the transistor 33. The microcontroller 21 of the measuring apparatus detects the
change in loading as a change in the excitation signal 34. The microcircuit 32
changes the loading of the excitation signal 34 in a controlled manner forming
the pulse pattern 6 read from the excitation signal 34 of the measuring
apparatus 3.
Fig. 2 presents the structure of one pulse pattern 6 according to the invention.
The pulse pattern 6 is in series mode and comprises an individualized
identification 7 for the position identifier, for determining the position identifier,
and also immediately following this a checksum 8 of the identification. When a
position identifier 4 that is individualized by means of identification is fitted in a
selected location in relation to the elevator hoistway 1, an explicit location in the
elevator hoistway corresponding to the identifier can also be determined.
Fig. 4 presents an arrangement according to the invention for determining the
position of a floor level in an elevator system. In the situation according to the
figure the measuring apparatus 3 fitted in connection with the elevator car
moves in the direction of the arrow past the position identifier 4 fitted into the
elevator hoistway. When the loop antenna 19 of the measuring apparatus 3
arrives from above into the immediate proximity of the position identifier 4, the
upper 9 of the two RFID units of the position identifier connects inductively to
the electromagnetic measuring signal 5 formed by the loop antenna 19 of the
measuring apparatus. The measuring apparatus 3 identifies the position
identifier by means of the identification of the RFID unit. In this case the
measuring apparatus 3 registers that the elevator car has arrived at the known
floor zone 35. When the measuring apparatus 3 moves farther downwards in
the direction of the arrow, the measuring apparatus arrives in the floor zone 36
according to the identification of the lower RFID unit 9'. The distance in the
direction of the movement of the elevator car between the RFID units 9, 9' is set
such that the floor zones 35, 36 determined by the RFID units 9, 9' partly
overlap each other. The floor level of the elevator is fitted in a place in which the
measuring apparatus 3 simultaneously registers the identification of both the
upper 9 and the lower 9' RFID unit.
Fig. 5 presents a corresponding arrangement for determining the lowermost
floor as well as the final limits of the elevator hoistway. When the measuring'
apparatus 3 arrives in the direction of the arrow at the position identifier 4
corresponding to the lowermost floor, the position of the floor is registered
according to the embodiment of Fig. 4. A second position identifier 4' of the
same type is fitted below the position identifier 4. The distance in the direction of
the movement of the elevator car between the position identifiers 4, 4' is set
such that the zones 36,37 determined by the lower RFID unit 9' of the upper
position identifier 4 and the upper RFID unit 9 of the lower position identifier 4'
partly overlap each other. The overlap between these zones 36, 37 forms a
direction-dependent end limit When it arrives at the direction-dependent end
limit the elevator car must change its direction upwards to leave the end zone. If
the elevator car however continues its travel farther downwards, the final limit is
reached. The final limit is determined in the zone 38 in which the measuring
apparatus 3 simultaneously registers the identifications of both the RFID units 9,
9' of the lower position identifier 4'. In this case the elevator control 29 prevents
movement of the elevator car by controlling a mechanical stopping apparatus.
The elevator control also prevents restarting of the run.
When determining the topmost floor of the elevator hoistway and also the upper
end limits of the floor, the position identifiers can be disposed in a
corresponding manner in the top part of the hoistway.
Fig. 6 presents an arrangement according to the invention for determining the
linear position of the elevator car. Hall sensors 11 are fitted to the measuring
apparatus 3 for measuring the external magnetic field. A permanently-
magnetized marking piece 12 (as viewed from the side) is fitted to the position
identifier 4. The marking piece 12 is of magnetic material in which two
consecutive magnetic areas 13, 13' have been made by drawing the marking
piece into a powerful external magnetic field. The magnetic poles of the
consecutive magnetic areas 13, 13' are made to be of opposite directions to
each other. The magnetic areas 13, 13' are arranged at a determined distance
from each other in the direction of movement of the elevator car. Five Hall
sensors 11 are fitted to the measuring apparatus 3 consecutively in the direction
of movement of the elevator car. When the measuring apparatus 3 arrives in the
proximity of the marking piece 12, the Hall sensors 11 of the measuring
apparatus register a change in the magnetic field. When the measuring
apparatus moves past the marking piece, each Hall sensor 11 forms a
proportional signal 35 to the magnetic field of the marking piece in relation to
the position according to Fig. 6. The perpendicular distance between the
marking piece 12 and the Hall sensors is in this case at most approx. 30mm,
and most preferably between approx. 10 mm - 15 mm. The phase difference
between the signals 35 in Fig. 6 is caused by the interplacement of the Hall
sensors. Since the aforementioned signals 35 are essentially sinusoidal in
relation to the position, the instantaneous linear position of the elevator car can
be determined on the basis of the instantaneous values of the signals 35, e.g.
with trigonometric calculations.
Fig. 7 presents an improvement to the arrangement according to Fig. 6. Four
separate magnetic areas are made in the marking piece 12 (as seen from the
front). The size of each magnetic area is 40mm X 30mm. The areas are
situated consecutively in the direction of movement of the elevator car such that
the distance between the center points of consecutive areas is 48mm. The
thickness of the marking piece is 8 mm. Five Hall sensors 11 are fitted to the
measuring apparatus 3 consecutively in the direction of movement of the
elevator car such that the distances between two consecutive sensors are
24mm, 36mm, 36mm, 24mm, respectively, starting from the edgemost. In Fig. 7
the Hall sensors 11 are disposed next to the marking piece 12 for the sake of
clarity. Fig. 7 also presents the signals 35 of the aforementioned Hall sensors
when the measuring apparatus 3 moves past the marking piece 12. The
instantaneous linear position of the elevator car is determined on the basis of
the instantaneous values of the signals 35. In this case the accuracy of the
linear position improves particularly at the point of the edgemost magnetic areas
of the marking piece 12.
Fig. 8 presents a construction of a measuring apparatus 3 according to the
invention. The measuring apparatus comprises an apparatus frame 15, which
comprises a mechanical fixing groove 16 for fixing the measuring apparatus.
The measuring apparatus comprises an output 17 for the measuring data. A
circuit board 18 is fixed to the apparatus frame 15. A circulating conductor is
fitted into the intermediate layer of the circuit board in the proximity of the edges
of the circuit board, which circulating conductor forms a loop antenna 19. A
transmitter 20 connected to an antenna is also fixed to the circuit board, as well
as a controller 21, which is connected to the transmitter 20. The transmitter 20
is controlled and also the excitation signal 34 supplied by the transmitter is read,
both with the controller 21, for determining the position identifier 4. In one
embodiment of the invention Hall sensors 11 are additionally fitted to the circuit
board 18 for measuring the external magnetic field.
In one embodiment of the invention the means 11 for measuring the external
magnetic field comprise a magnetoresistive sensor.
The invention is described above by the aid of a few examples of its
embodiment. It is obvious to the person skilled in the art that the invention is not
limited to the embodiments described above, but that many other applications
are possible within the scope of the inventive concept defined by the claims
presented below.
It is obvious to the person skilled in the art that the elevator system according to
the invention can comprise a counterweight, or the elevator system can also be
without a counterweight.
It is also obvious to the person skilled in the art that the measuring apparatus
according to the invention can be fitted in a selected location with relation to the
elevator hoistway, in which case the position identifier according to the invention
can be fitted in connection with the elevator car. In this case the interpositioning
of the position identifier and the measuring apparatus is fitted in the manner
presented in the invention.
It is further obvious to the person skilled in the art that the elevator system
according to the invention can comprise more than one elevator car fitted into
the same elevator hoistway. In this case the measuring apparatus according to
the invention can be fitted in connection with more than one elevator car fitted
into the same elevator hoistway.
It is additionally obvious to the person skilled in the art that the measuring
apparatus according to the invention can be fixed in connection with the
mechanics that moves along with the elevator car, such as in connection with
the sling of the elevator car or e.g. the counterweight.
It is also obvious to the skilled person that more position identifiers can be fitted
to the end zone of the elevator hoistway in a corresponding manner, for
determining possible additional end limits. In this case the safety of the elevator
system can be further improved e.g. when the speed of the elevator car and/or
the movement area of the mechanical end buffer increases.
CLAIMS
1. Arrangement for determining the position of an elevator car (1) in an
elevator hoistway (2), characterized in that the arrangement comprises:
- a measuring apparatus (3) fitted in connection with the elevator
car (1), which measuring apparatus is arranged to form an
electromagnetic radio-frequency measuring signal (5), for
determining the position of the elevator car
- a position identifier (4) fitted in a selected location in relation to the
elevator hoistway (2), which position identifier is arranged to
connect inductively to the aforementioned electromagnetic
measuring signal (5), and also after connecting to send a
determined pulse pattern (6) to the measuring apparatus (3) via
the aforementioned measuring signal (5)
2. Arrangement according to claim 1, characterized in that the pulse
pattern (6) formed by the aforementioned position identifier (4) comprises
an identification (7) of the position identifier as well as a checksum (8).
3. Arrangement according to any of the claims above, characterized in
that the position identifier (4) comprises at least two RFID units (9,9'),
the distance between which in the direction of the movement of the
elevator car is determined.
4. Arrangement according to any of the claims above, characterized in
that means (11) for measuring an external magnetic field are arranged in
the measuring apparatus (3), and in that the position identifier (4)
comprises a permanently-magnetized marking piece (12), which marking
piece comprises at least two consecutive magnetic areas (13,13'), the
magnetic poles of which consecutive magnetic areas are of opposite
directions to each other, and which consecutive magnetic areas are
arranged at a determined distance from each other in the direction of
movement of the elevator car.
5. Arrangement according to claim 4, characterized in that means (11) for
measuring an external magnetic field are arranged in the measuring
apparatus (3), and in that the position identifier (4) comprises a
permanently-magnetized marking piece (12), which marking piece
comprises four magnetic areas (13,13') fitted consecutively, the magnetic
poles of two of which consecutive magnetic areas are always of opposite
directions to each other, and which consecutive magnetic areas are
arranged at a determined distance from each other in the direction of
movement of the elevator car.
6. Method for determining the position of an elevator car (1) in an elevator
hoistway (2), characterized in that:
- a measuring apparatus (3) that moves along with the elevator car
is fitted in connection with the elevator car (1)
- the measuring apparatus (3) is arranged to form an
electromagnetic radio-frequency measuring signal (5), for
determining the position of the elevator car
- a position identifier (4) is fitted in a selected location in relation to
the elevator hoistway (2)
- the position identifier (4) is arranged to connect inductively to the
aforementioned electromagnetic measuring signal (5), and also
- after connecting to send a determined pulse pattern (6) to the
measuring apparatus (3) via the aforementioned measuring signal
(5)
7. Method according to claim 6, characterized in that:
- an identification (7) of the position identifier (4) is fitted as a part of
the pulse pattern (6) formed by the position identifier
- a checksum (8) of the identification is fitted as a part of the pulse
pattern (6) formed by the position identifier
8. Method according to claim 6 or 7, characterized in that:
- at least two RFID units (9,9') are fitted into the position identifier
- the aforementioned RFID units are arranged at a determined
distance from each other in the direction of the movement of the
elevator car
9. Method according to any of claims 6 - 8, characterized in that:
- means for measuring (11) the external magnetic field are fitted to
the measuring apparatus (3)
- at least two adjacent permanently-magnetized magnetic areas
(13,13') are made in the marking piece (12) such that the
magnetic poles of adjacent magnetic areas are of opposite
directions to each other
- the permanently-magnetized marking piece (12) is fitted into the
position identifier (4) such that the aforementioned adjacent
magnetic areas (13,13') come to the set distance from each other
in the direction of movement of the elevator car
10. Measuring apparatus (3) for determining the position of a moving object
(1), characterized in that the measuring apparatus comprises:
- an apparatus frame (15), which comprises a mechanical fixing
interface (16) to the moving object (1)
- an output (17) for the position information of the moving object
- a circuit board (18) fixed to the apparatus frame, and fitted to the
circuit board:
a loop antenna (19) formed on the circuit board
- a transmitter (20) connected to the antenna
- a controller (21) connected to the transmitter
and in that the circuit board (18) is fitted to be connected to the
moving object (1) via the apparatus frame (15) such that the surface
(22) of the circuit board is essentially in the direction of movement,
and in that the loop antenna (19) of the circuit board is arranged to
form an electromagnetic radio-frequency measuring signal (5) in
essentially the perpendicular direction to the movement of the
object for determining the position of the moving object (1).
H.Position identifier (4) for determining the position of a moving object (1),
characterized in that the position identifier comprises:
- an RFID unit (9,9')
- a fixing interface (23) for fixing the position identifier in
relation to the path of movement (2) of the object
and in that the position identifier (4) is fitted to be fixed for aligning the
antenna of the RFID unit (9,9') such that the antenna connects
inductively to the radio-frequency measuring signal (5) formed in an
essentially perpendicular direction to the movement of the object.

The invention relates to an arrangement and a method for
determining the position of an elevator car (1) in the elevator hoistway (2).
The arrangement comprises a measuring apparatus (3) fitted in connection
with the elevator car (1). The measuring apparatus is arranged to form an
electromagnetic radio-frequency measuring signal (5), for determining the
position of the elevator car. The arrangement also comprises a position
identifier (4) fitted in a selected location in relation to the elevator hoistway (2).
The position identifier is arranged to connect inductively to the
aforementioned electromagnetic measuring signal (5), and also after it has
connected to send a determined pulse partern using the aforementioned
measuring signal (5).